0001438533-19-000036 | 10-Q | XBRL Viewer

INVENTORY (Tables)

9 Months Ended

Sep. 30, 2019

Inventory, net of reserves, consisted of the following at September 30, 2019 and December 31, 2018 (in thousands):



	September 30, 2019		December 31, 2018
Raw materials	$	3,078	$	4,689
Finished goods	2,186		930
Total inventory	$	5,264	$	5,619

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 65,188	$ 102,873
Marketable securities	341,835	368,668
Accounts receivable, net	16,781	12,662
Inventory, net	5,264	5,619
Prepaid expenses and other current assets	8,628	4,140
Prepaid taxes	2,022	1,716
Total current assets	439,718	495,678
Property and equipment, net	2,910	3,146
Other non-current assets	12,453	7,709
Investment-equity	0	15,000
Intangible assets, net	157,799	186,691
Goodwill	936	936
Total assets	613,816	709,160
Current liabilities:
Accounts payable	13,832	6,954
Accrued expenses	47,874	49,695
Other current liabilities	8,411	6,165
Business combination-related contingent consideration	17,900	19,350
2019 Convertible debt	0	22,457
Total current liabilities	88,017	104,621
2025 Convertible debt	202,355	195,091
Other non-current liabilities	21,487	17,545
Business combination-related contingent consideration, less current portion	56,000	73,650
Total liabilities	367,859	390,907
Stockholders' Equity:
Preferred stock $0.0001 par value; 20,000,000 shares authorized; 0 issued and outstanding as of September 30, 2019 and December 31, 2018	0	0
Common stock $0.0001 par value; 100,000,000 shares authorized; 42,958,401 and 41,389,524 issued and outstanding as of September 30, 2019 and December 31, 2018, respectively	4	4
Additional paid-in capital	630,966	589,795
Accumulated deficit	(386,185)	(270,017)
Accumulated other comprehensive income (loss)	1,172	(1,529)
Total stockholders' equity	245,957	318,253
Total liabilities and stockholders' equity	$ 613,816	$ 709,160

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Cash Flows From Operating Activities:
Net loss	$ (116,168)	$ (95,223)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	15,118	13,789
Non-cash interest expense	1,134	1,115
(Accretion) amortization of discounts/premiums on investments, net	(779)	749
Amortization of debt discount and issuance costs	7,397	980
Provision for Inventory	(646)	1,625
Share based compensation	16,608	14,920
Change in fair value of contingent consideration	(12,180)	22,387
Payments related to change in fair value of contingent consideration	(4,329)	(6,852)
Loss on the extinguishment of debt	0	17,042
Impairment of IPR&D intangible assets	25,500	0
Impairment of long-term investment	15,000	0
Unrealized foreign currency transaction gain (loss)	539	270
Other	15	(15)
Changes in operating assets and liabilities, net of business acquisitions:
Accounts receivable	(3,989)	1,346
Inventory	947	(1,428)
Other current and non-current operating assets	(9,629)	(2,183)
Accounts payable and accrued expenses	4,962	6,991
Other current and non-current operating liabilities	6,778	3,094
Net cash used in operating activities	(53,722)	(21,393)
Cash Flows From Investing Activities:
Purchase of fixed assets	(286)	(727)
Cash paid for intangible assets	(11,299)	(15,108)
Proceeds from the sale/maturity of marketable securities	180,818	96,166
Purchase of marketable securities	(150,950)	(219,820)
Cash paid for investments - equity	0	(15,000)
Net cash provided by (used in) investing activities	18,283	(154,489)
Cash Flows From Financing Activities:
Payment of acquisition-related contingent consideration	(2,562)	(8,842)
Payment of guaranteed minimum royalty	(1,559)	(1,500)
Payment of other liability	0	(750)
Proceeds from exercise of warrants	0	4,274
Proceeds from exercise of stock options	944	10,379
Proceeds from 2025 convertible senior notes	0	276,000
Repayment of 2019 convertible senior notes	0	(40,203)
Payment of debt issuance and financing costs	0	(8,820)
Other financing activities	1,005	800
Net cash (used in) provided by financing activities	(2,172)	231,338
Effect of exchange rate changes on cash	(74)	(30)
Net change in cash and cash equivalents	(37,685)	55,426
Cash and cash equivalents, beginning of year	102,873	99,394
Cash and cash equivalents, end of period	$ 65,188	$ 154,820

INTANGIBLE ASSETS - Amortization (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Finite-Lived Intangible Assets [Line Items]
Total amortization expense	$ 5,007	$ 4,625	$ 14,594	$ 13,319
Research and development
Finite-Lived Intangible Assets [Line Items]
Total amortization expense	292	292	866	684
Selling, general and administrative
Finite-Lived Intangible Assets [Line Items]
Total amortization expense	$ 4,715	$ 4,333	$ 13,728	$ 12,635

BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES	BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES The accompanying unaudited condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto included in the 2018 10-K filed with the SEC on February 26, 2019. The accompanying condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States (“GAAP”) for interim financial information, the instructions for Form 10-Q and the rules and regulations of the SEC. Accordingly, since they are interim statements, the accompanying condensed consolidated financial statements do not include all of the information and notes required by GAAP for annual financial statements, but reflect all adjustments consisting of normal, recurring adjustments, that are necessary for a fair presentation of the financial position, results of operations and cash flows for the interim periods presented. Interim results are not necessarily indicative of the results that may be expected for any future periods. The December 31, 2018 balance sheet information was derived from the audited financial statements as of that date. Certain reclassifications have been made to the prior period consolidated financial statements to conform to the current period presentation. A summary of the significant accounting policies applied in the preparation of the accompanying condensed consolidated financial statements follows: Principles of Consolidation The unaudited condensed consolidated financial statements represent the consolidation of the accounts of the Company and its subsidiaries in conformity with GAAP. All intercompany accounts and transactions have been eliminated in consolidation. Revenue Recognition The Company recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration which the entity expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that an entity determines are within the scope of Topic 606, the entity performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the entity satisfies a performance obligation. The Company only applies the five-step model to contracts when it is probable that the entity will collect substantially all the consideration it is entitled to in exchange for the goods or services it transfers to the customer. See Note 3 for further discussion. Research and Development Expenses Research and development expenses are comprised of salaries and bonuses, benefits, non-cash share-based compensation, license fees, costs paid to third-party contractors to perform research, conduct clinical trials and pre/non-clinical trials, develop drug materials, and associated overhead expenses and facilities. We also incur indirect costs that are not allocated to specific programs because such costs benefit multiple development programs and allow us to increase our pharmaceutical development capabilities. These consist of internal shared resources related to the development and maintenance of systems and processes applicable to all of our programs. Clinical Trial Expenses Our clinical trials are conducted pursuant to contracts with contract research organizations ("CROs") that support conducting and managing clinical trials. The financial terms and activities of these agreements vary from contract to contract and may result in uneven expense levels. Generally, these agreements set forth activities that drive the recording of expenses such as start-up, initiation activities, enrollment, treatment of patients, or the completion of other clinical trial activities. Expenses related to clinical trials are accrued based on our estimates and/or representations from service providers regarding work performed, including actual level of patient enrollment, progress of the clinical trials, and completion of patient studies. Other incidental costs related to patient enrollment or treatment are accrued when reasonably certain. If the amounts we are obligated to pay under our clinical trial agreements are modified (for instance, as a result of changes in the clinical trial protocol or scope of work to be performed), we adjust our accruals accordingly on a prospective basis. Revisions to our contractual payment obligations are charged to expense in the period in which the facts that give rise to the revision become reasonably certain. We currently have two Phase 3 clinical trials in process that are in varying stages of activity, with ongoing non-clinical support trials. As such, clinical trial expenses will vary depending on all the factors set forth above and may fluctuate significantly from quarter to quarter. Adoption of New Accounting Standards In February 2016, the FASB issued ASU No. 2016-02, Leases. The new standard establishes a right-of-use ("ROU") model that requires a lessee to record a ROU asset and a lease liability on the balance sheet for all leases with terms longer than 12 months. Leases will be classified as either finance or operating, with classification affecting the pattern of expense recognition in the income statement. The new standard is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. See Note 6 for further discussion. Recently Issued Accounting Pronouncements From time to time, new accounting pronouncements are issued by the FASB or other standard setting bodies. Unless otherwise noted, the Company believes that the impact of recently issued standards that are not yet effective will not have a material impact on its consolidated financial position or results of operations upon adoption. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. Topic 326 amends guidance on reporting credit losses for assets held at amortized cost basis and available-for-sale debt securities. For assets held at amortized cost basis, Topic 326 eliminates the probable initial recognition threshold in current GAAP and, instead, requires an entity to reflect its current estimate of all expected credit losses. The allowance for credit losses is a valuation account that is deducted from the amortized cost basis of the financial assets to present the net amount expected to be collected. For available-for-sale debt securities, credit losses should be measured in a manner similar to current GAAP, however Topic 326 will require that credit losses be presented as an allowance rather than as a write-down. This ASU update affects entities holding financial assets and net investment in leases that are not accounted for at fair value through net income. The amendments affect loans, debt securities, trade receivables, net investments in leases, off balance sheet credit exposures, reinsurance receivables, and any other financial assets not excluded from the scope that have the contractual right to receive cash. This update is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. As of September 30, 2019, the Company held $341.8 million in available-for-sale debt securities. If adopted as of September 30, 2019, this ASU update would not have a material impact on the Company's financial statements.

ACCOUNTS RECEIVABLE (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Receivables [Abstract]
Accounts receivable, net of reserves	$ 16,781	$ 12,662

FAIR VALUE MEASUREMENTS - Acquisition-related Contingent Consideration (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
L-UDCA write-off			$ (4,329)	$ (6,852)	$ 1,000	$ (5,700)	$ (2,300)
Change in fair value of contingent consideration	$ (702)	$ 16,601	5,820	$ 22,387
Level 3
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance			93,000
L-UDCA write-off			(18,000)
Contractual payments included in accrued liabilities at September 30, 2019			(2,245)
Contractual payments			(4,556)
Foreign currency impact			(119)
Ending balance	$ 73,900		$ 73,900		$ 93,000

CONVERTIBLE NOTES PAYABLE

9 Months Ended

Sep. 30, 2019

Debt Disclosure [Abstract]

CONVERTIBLE NOTES PAYABLE

Convertible Senior Notes Due 2025

On September 10, 2018, the Company completed its registered underwritten public offering of $276.0 million aggregate principal amount of 2.50% Convertible Senior Notes due 2025 ("2025 Notes"), and entered into a base indenture and supplemental indenture agreement ("2025 Indenture") with respect to the 2025 Notes. The 2025 Notes will mature on September 15, 2025 ("Maturity Date”), unless earlier repurchased, redeemed, or converted. The 2025 Notes are senior unsecured obligations of the Company and bear interest at an annual rate of 2.50%, payable semi-annually in arrears on March 15 and September 15 of each year, commencing March 15, 2019.

The composition of the Company’s 2025 Notes are as follows (in thousands):



	September 30, 2019			December 31, 2018
2.50% convertible senior notes due 2025	$	276,000		$	276,000
Unamortized debt discount	(68,245		)	(74,836		)
Unamortized debt issuance costs	(5,400		)	(6,073		)
Total 2025 Notes, net of unamortized debt discount and debt issuance costs	$	202,355		$	195,091

The net proceeds from the issuance of the 2025 Notes were approximately $267.2 million, after deducting commissions and the offering expenses payable by the Company. A portion of the net proceeds from the 2025 Notes was used by the Company to repurchase $23.4 million aggregate principal amount of its then-outstanding 4.5% senior convertible notes due 2019 in privately-negotiated transactions.

Holders may convert their 2025 Notes at their option only in the following circumstances: (1) during any calendar quarter commencing after the calendar quarter ending on December 31, 2018 (and only during such calendar quarter), if the last reported sale price per share of the Company’s common stock for each of at least 20 trading days, whether or not consecutive, during the period of 30 consecutive trading days ending on, and including, the last trading day of the immediately preceding calendar quarter exceeds 130% of the conversion price on the applicable trading day; (2) during the five consecutive business days immediately after any 10 consecutive trading day period (“measurement period”) if the trading price per $1,000 principal amount of 2025 Notes for each trading day of the measurement period was less than 98% of the product of the last reported sale price per share of the Company’s common stock on such trading day and the conversion rate on such trading day; (3) upon the occurrence of certain corporate events or distributions on the Company’s common stock; (4) if the Company calls the 2025 Notes for redemption; and (5) at any time from, and including, May 15, 2025 until the close of business on the scheduled trading day immediately before the Maturity Date. The Company will settle conversions by paying or delivering, as applicable, cash, shares of the Company’s common stock, or a combination of cash and shares of the Company’s common stock, at the Company’s election, based on the applicable conversion rate.

The initial conversion rate for the 2025 Notes is 25.7739 shares of the Company’s common stock per $1,000 principal amount of 2025 Notes, which represents an initial conversion price of approximately $38.80 per share. If a “make-whole fundamental change” (as defined in the 2025 Indenture) occurs, then the Company will, in certain circumstances, increase the conversion rate for a specified period of time.

The 2025 Notes will be redeemable, in whole or in part, at the Company’s option at any time, and from time to time, on or after September 15, 2022 and, in the case of any partial redemption, on or before the 40th scheduled trading day before the Maturity Date, at a cash redemption price equal to the principal amount of the 2025 Notes to be redeemed, plus accrued and unpaid interest, if any, to, but excluding, the redemption date, but only if the last reported sale price per share of the Company’s common stock exceeds 130% of the conversion price on each of at least 20 trading days during the 30 consecutive trading days ending on, and including, the trading day immediately before the date the Company sends the related redemption notice. If a fundamental change (as defined in the 2025 Indenture) occurs, then, subject to certain exceptions, holders may require the Company to repurchase their 2025 Notes at a cash repurchase price equal to the principal amount of the 2025 Notes to be repurchased, plus accrued and unpaid interest, if any, to, but excluding, the fundamental change repurchase date.

In the event of conversion, holders would forgo all future interest payments, any unpaid accrued interest and the possibility of further stock price appreciation. Upon the receipt of conversion requests, the settlement of the 2025 Notes will be paid pursuant to the terms of the 2025 Indenture. In the event that all of the 2025 Notes are converted, the Company would be required to repay the $276.0 million principal amount and any conversion premium in any combination of cash and shares of its common stock at the Company’s option. In addition, calling the 2025 Notes for redemption will constitute a “make whole fundamental change."

The 2025 Notes are the Company’s general unsecured obligations that rank senior in right of payment to all of its indebtedness that is expressly subordinated in right of payment to the 2025 Notes, and equal in right of payment to the Company’s unsecured indebtedness.

The 2025 Notes are classified on the Company’s Condensed Consolidated Balance Sheets at September 30, 2019 as long-term debt.

Under ASC 470-20, Debt with Conversion and Other Options, an entity must separately account for the liability and equity components of convertible debt instruments (such as the 2025 Notes) that may be settled entirely or partially in cash upon conversion, in a manner that reflects the issuer’s economic interest cost. The liability component of the instrument is valued in a manner that reflects the market interest rate for a similar nonconvertible instrument at the date of issuance. The initial carrying value of the liability component was $198.6 million. The equity component of $77.4 million, representing the conversion option, was determined by deducting the fair value of the liability component from the par value of the 2025 Notes and is recorded in additional paid-in capital on the consolidated balance sheet at the issuance date. That equity component is treated as a discount on the liability component of the 2025 Notes, which is amortized over the seven-year term of the 2025 Notes using the effective interest rate method. The equity component is not re-measured as long as it continues to meet the conditions for equity classification. The Company allocated the total transaction costs of approximately $8.8 million related to the issuance of the 2025 Notes to the liability and equity components of the 2025 Notes based on their relative values. Transaction costs attributable to the liability component are amortized to interest expense over the seven-year term of the 2025 Notes, and transaction costs attributable to the equity component are netted with the equity component in stockholders’ equity.

The effective interest rate on the liability components of the 2025 Notes for the period from the date of issuance through September 30, 2019 was 7.7%. The following table sets forth total interest expense recognized related to the 2025 Notes (in thousands):



	Three Months Ended September 30,				Nine Months Ended September 30,
	2019		2018		2019		2018
Contractual interest expense	$	1,725	$	383	$	5,175	$	383
Amortization of debt discount	2,239		468		6,591		468
Amortization of debt issuance costs	224		50		672		50
Total interest expense for the 2025 Notes	$	4,188	$	901	$	12,438	$	901

The 2025 Notes do not contain any financial or operating covenants or any restrictions on the payment of dividends, the issuance of other indebtedness or the issuance or repurchase of securities by the Company. The 2025 Indenture contains customary events of default with respect to the 2025 Notes, including failure to pay (for more than 30 days) interest when due and certain types of bankruptcy or insolvency involving the Company. Upon an event of default involving certain types of bankruptcy insolvency, 100% of the outstanding principal and accrued and unpaid interest on the 2025 Notes will automatically become due and payable, and upon other events of default, the trustee under the 2025 Indenture or the holders of at least 25% of the outstanding principal amount of the 2025 Notes may declare 100% of the principal and accrued and unpaid interest on the 2025 Notes to be immediately due and payable.

Senior Convertible Notes Due 2019

On May 29, 2014, the Company entered into a Note Purchase Agreement relating to a private placement by the Company of $46.0 million aggregate principal amount of 4.50% senior convertible notes due 2019 (the “2019 Notes”) which were convertible into shares of the Company’s common stock at an initial conversion price of $17.41 per share. The conversion price was subject to customary anti-dilution protection. The 2019 Notes bore interest at a rate of 4.5% per annum, payable semiannually in arrears on May 15 and November 15 of each year. The 2019 Notes had a maturity date of May 30, 2019 and there were no contractual payments due prior to that date.

In September 2018, the Company used part of the net proceeds from the issuance of the 2025 Notes to repurchase $23.4 million aggregate principal amount of the 2019 Notes in privately-negotiated transactions for approximately $40.2 million in cash. The partial repurchase of the 2019 Notes resulted in a $17.0 million loss on early extinguishment of debt in September 2018.

In May 2019, the remaining $22.6 million outstanding principal amount of 2019 Notes was converted by the holders thereof into approximately 1.3 million shares of common stock.

The composition of the Company’s 2019 Notes at December 31, 2018 was as follows (in thousands):



	December 31, 2018
4.50% senior convertible notes due 2019	$	22,590
Unamortized debt discount	(125		)
Unamortized debt issuance costs	(8		)
Total 2019 Notes, net of unamortized debt discount and debt issuance costs	$	22,457

INCOME TAXES (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
INCOME TAXES (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Tax Disclosure [Abstract]
Effective tax rate	1.40%	(0.80%)	0.00%	(0.90%)
Income tax benefit (expense)	$ 523	$ (415)	$ 53	$ (811)

CONVERTIBLE NOTES PAYABLE - Additional Information (Details) $ / shares in Units, shares in Millions	1 Months Ended		3 Months Ended		9 Months Ended
	May 31, 2019 USD ($) shares	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) day $ / shares	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) day $ / shares	Sep. 30, 2018 USD ($)	Sep. 10, 2018 USD ($)	May 29, 2014 USD ($) $ / shares
Debt Instrument [Line Items]
Debt instrument, repurchase amount			$ 23,400,000		$ 23,400,000
Gain (loss) on extinguishment of debt			0	$ (17,042,000)	$ 0	$ (17,042,000)
Issuance of common stock from maturity of the 2019 Convertible debt outstanding (in shares) \| shares	1.3
Senior Notes Due 2025
Debt Instrument [Line Items]
Debt instrument term					7 years
Note Purchase Agreement \| Senior convertible notes due 2019
Debt Instrument [Line Items]
Interest rate percentage								4.50%
Initial conversion price (in dollars per share) \| $ / shares								$ 17.41
Credit agreement amount								$ 46,000,000.0
Senior Notes \| Senior Notes Due 2025
Debt Instrument [Line Items]
Long-term debt, excluding current maturities			$ 276,000,000.0		$ 276,000,000.0		$ 276,000,000.0
Interest rate percentage			2.50%		2.50%		2.50%
Proceeds from issuance of debt					$ 267,200,000
Debt instrument, convertible, threshold percentage of stock price trigger					130.00%
Conversion ratio					0.0257739
Initial conversion price (in dollars per share) \| $ / shares			$ 38.80		$ 38.80
Debt conversion, liability			$ 198,600,000		$ 198,600,000
Debt conversion, equity					77,400,000
Debt issuance costs, net			$ 8,800,000		$ 8,800,000
Debt instrument, interest rate, effective percentage			7.70%		7.70%
Debt redeemable upon bankruptcy insolvency			100.00%		100.00%
Minimum percentage of holders required to declare redemption			25.00%		25.00%
Debt redeemable upon declaration of holders			100.00%		100.00%
Senior Notes \| Convertible Notes Due 2019
Debt Instrument [Line Items]
Interest rate percentage			4.50%		4.50%
Debt instrument, repurchase amount		$ 23,400,000		$ 23,400,000		$ 23,400,000
Debt instrument, convertible, threshold trading days \| day					20
Debt instrument, convertible, threshold consecutive trading days \| day					30
Debt instrument, convertible, threshold percentage of stock price trigger					130.00%
Debt instrument, convertible, threshold consecutive days measuring period \| day			10		10
Trading price per principal, percentage					98.00%
Repayments of debt		40,200,000
Gain (loss) on extinguishment of debt		$ (17,000,000.0)
Long-term debt and capital lease obligations	$ 22,600,000

BASIS OF PRESENTATION AND SIGNIFICANT ACCCOUNTING POLICIES (Policies)	9 Months Ended
	Sep. 30, 2019
Accounting Policies [Abstract]
Principles of Consolidation	Principles of Consolidation The unaudited condensed consolidated financial statements represent the consolidation of the accounts of the Company and its subsidiaries in conformity with GAAP. All intercompany accounts and transactions have been eliminated in consolidation.
Revenue Recognition	Revenue Recognition The Company recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration which the entity expects to receive in exchange for those goods or services. To determine revenue recognition for arrangements that an entity determines are within the scope of Topic 606, the entity performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the entity satisfies a performance obligation. The Company only applies the five-step model to contracts when it is probable that the entity will collect substantially all the consideration it is entitled to in exchange for the goods or services it transfers to the customer. Deductions from Revenue Revenues from product sales are recorded at the net sales price, which includes provisions resulting from discounts, rebates and co-pay assistance that are offered to customers, health care providers, payors and other indirect customers relating to the Company’s sales of its products. These provisions are based on the amounts earned or to be claimed on the related sales and are classified as a reduction of accounts receivable (if the amount is payable to a customer) or as a current liability (if the amount is payable to a party other than a customer). Where appropriate, these reserves take into consideration the Company’s historical experience, current contractual and statutory requirements, specific known market events and trends, industry data and forecasted customer buying and payment patterns. Overall, these reserves reflect the Company’s best estimates of the amount of consideration to which it is entitled based on the terms of the contract. If actual results in the future vary from the Company’s provisions, the Company will adjust the provision, which would affect net product revenue and earnings in the period such variances become known. Our historical experience is that such adjustments have been immaterial. Government Rebates: We calculate the rebates that we will be obligated to provide to government programs and deduct these estimated amounts from our gross product sales at the time the revenues are recognized. Allowances for government rebates and discounts are established based on actual payer information, which is reasonably estimated at the time of delivery, and the government-mandated discounts applicable to government-funded programs. Rebate discounts are included in other current liabilities in the accompanying consolidated balance sheets. Commercial Rebates: We calculate the rebates that we incur due to contracts with certain commercial payors and deduct these amounts from our gross product sales at the time the revenues are recognized. Allowances for commercial rebates are established based on actual payer information, which is reasonably estimated at the time of delivery. Rebate discounts are included in other current liabilities in the accompanying consolidated balance sheets. Prompt Pay Discounts: We offer discounts to certain customers for prompt payments. We accrue for the calculated prompt pay discount based on the gross amount of each invoice for those customers at the time of sale. Product Returns: Consistent with industry practice, we offer our customers a limited right to return product purchased directly from the Company, which is principally based upon the product’s expiration date. Generally, shipments are only made upon a patient prescription thus returns are minimal. Co-pay Assistance: We offer a co-pay assistance program, which is intended to provide financial assistance to qualified commercially insured patients with prescription drug co-payments required by payors. The calculation of the accrual for co-pay assistance is based on an identification of claims and the cost per claim associated with product that has been recognized as revenue.
Research and Development Expense	Research and Development Expenses Research and development expenses are comprised of salaries and bonuses, benefits, non-cash share-based compensation, license fees, costs paid to third-party contractors to perform research, conduct clinical trials and pre/non-clinical trials, develop drug materials, and associated overhead expenses and facilities. We also incur indirect costs that are not allocated to specific programs because such costs benefit multiple development programs and allow us to increase our pharmaceutical development capabilities. These consist of internal shared resources related to the development and maintenance of systems and processes applicable to all of our programs.
Clinical Trial Expenses	Clinical Trial Expenses Our clinical trials are conducted pursuant to contracts with contract research organizations ("CROs") that support conducting and managing clinical trials. The financial terms and activities of these agreements vary from contract to contract and may result in uneven expense levels. Generally, these agreements set forth activities that drive the recording of expenses such as start-up, initiation activities, enrollment, treatment of patients, or the completion of other clinical trial activities. Expenses related to clinical trials are accrued based on our estimates and/or representations from service providers regarding work performed, including actual level of patient enrollment, progress of the clinical trials, and completion of patient studies. Other incidental costs related to patient enrollment or treatment are accrued when reasonably certain. If the amounts we are obligated to pay under our clinical trial agreements are modified (for instance, as a result of changes in the clinical trial protocol or scope of work to be performed), we adjust our accruals accordingly on a prospective basis. Revisions to our contractual payment obligations are charged to expense in the period in which the facts that give rise to the revision become reasonably certain. We currently have two Phase 3 clinical trials in process that are in varying stages of activity, with ongoing non-clinical support trials. As such, clinical trial expenses will vary depending on all the factors set forth above and may fluctuate significantly from quarter to quarter.
Adoption of New Accounting Standards and Recently Issued Accounting Pronouncements	Adoption of New Accounting Standards In February 2016, the FASB issued ASU No. 2016-02, Leases. The new standard establishes a right-of-use ("ROU") model that requires a lessee to record a ROU asset and a lease liability on the balance sheet for all leases with terms longer than 12 months. Leases will be classified as either finance or operating, with classification affecting the pattern of expense recognition in the income statement. The new standard is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. See Note 6 for further discussion. Recently Issued Accounting Pronouncements From time to time, new accounting pronouncements are issued by the FASB or other standard setting bodies. Unless otherwise noted, the Company believes that the impact of recently issued standards that are not yet effective will not have a material impact on its consolidated financial position or results of operations upon adoption. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. Topic 326 amends guidance on reporting credit losses for assets held at amortized cost basis and available-for-sale debt securities. For assets held at amortized cost basis, Topic 326 eliminates the probable initial recognition threshold in current GAAP and, instead, requires an entity to reflect its current estimate of all expected credit losses. The allowance for credit losses is a valuation account that is deducted from the amortized cost basis of the financial assets to present the net amount expected to be collected. For available-for-sale debt securities, credit losses should be measured in a manner similar to current GAAP, however Topic 326 will require that credit losses be presented as an allowance rather than as a write-down. This ASU update affects entities holding financial assets and net investment in leases that are not accounted for at fair value through net income. The amendments affect loans, debt securities, trade receivables, net investments in leases, off balance sheet credit exposures, reinsurance receivables, and any other financial assets not excluded from the scope that have the contractual right to receive cash. This update is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. As of September 30, 2019, the Company held $341.8 million in available-for-sale debt securities. If adopted as of September 30, 2019, this ASU update would not have a material impact on the Company's financial statements.
Marketable Securities	The primary objective of the Company’s investment portfolio is to enhance overall returns while preserving capital and liquidity. The Company’s investment policy limits interest-bearing security investments to certain types of instruments issued by institutions with primarily investment grade credit ratings and places restrictions on maturities and concentration by asset class and issuer. All available-for-sale securities are held in current assets regardless of contractual maturities exceeding one year, as the Company has the ability to sell them within the next twelve months. The Company reviews the available-for-sale investments for other-than-temporary declines in fair value below cost basis each quarter and whenever events or changes in circumstances indicate that the cost basis of an asset may not be recoverable. This evaluation is based on a number of factors, including the length of time and the extent to which the fair value has been below the cost basis and adverse conditions related specifically to the security, including any changes to the credit rating of the security, and the intent to sell, or whether the Company will more likely than not be required to sell the security before recovery of its amortized cost basis. The assessment of whether a security is other-than-temporarily impaired could change in the future due to new developments or changes in assumptions related to any particular security.
Fair Value Measurement	Financial Instruments and Fair Value The Company accounts for financial instruments in accordance with ASC 820, Fair Value Measurements and Disclosures (“ASC 820”). ASC 820 establishes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to unobservable inputs (Level 3 measurements). The three levels of the fair value hierarchy under ASC 820 are described below: Level 1 – Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities; Level 2 – Quoted prices in markets that are not active or financial instruments for which all significant inputs are observable, either directly or indirectly; and Level 3 – Prices or valuations that require inputs that are both significant to the fair value measurement and unobservable. The valuation techniques used to measure the fair value of the Company’s marketable securities and all other financial instruments, all of which have counter-parties with high credit ratings, were valued based on quoted market prices or model driven valuations using significant inputs derived from or corroborated by observable market data. Based on the fair value hierarchy, the Company classified marketable securities within Level 2. In estimating the fair value of the Company’s contingent consideration, the Company used the Monte Carlo Simulation model as of September 30, 2019 and December 31, 2018. Based on the fair value hierarchy, the Company classified the fair value measurement of contingent consideration within Level 3. Financial instruments with carrying values approximating fair value include cash and cash equivalents, accounts receivable, and accounts payable, due to their short-term nature.
Income (Loss) Per Share	Basic and diluted net loss per common share is calculated by dividing net loss applicable to common stockholders by the weighted-average number of common shares outstanding during the period, without consideration of common stock equivalents. The Company’s potentially dilutive shares, which include outstanding stock options, restricted stock units, warrants, and shares issuable upon conversion of the 2019 Notes and 2025 Notes, are considered to be common stock equivalents and are only included in the calculation of diluted net loss per share when their effect is dilutive.

LEASES - Future Minimum Rent Commitments (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Jan. 01, 2019	Jul. 31, 2016
Leases [Abstract]
2019	$ 787
2020	2,958
2021	2,486
2022	2,560
2023	2,637
Thereafter	1,585
Total undiscounted future minimum payments	13,013	$ 14,000
Present value discount	(2,538)
Total lease liability	10,475	11,300
Lease incentives	(1,543)	(1,800)	$ (2,300)
Straight line lease expense in excess of cash payments	(1,585)
Total ROU asset	$ 7,347	$ 7,900

INVENTORY (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Inventory Disclosure [Abstract]
Raw materials	$ 3,078	$ 4,689
Finished goods	2,186	930
Total inventory	5,264	5,619
Inventory reserve	$ 2,400	$ 1,800

DISPOSITIONS	9 Months Ended
DISPOSITIONS	Sep. 30, 2019
Discontinued Operations and Disposal Groups [Abstract]
DISPOSITIONS	DISPOSITIONS In June 2016, the Company acquired certain rights to its product candidate L-UDCA for $0.5 million cash. At the same time the Company established a related non-cash asset of $25.5 million for IPR&D and a liability of $25.0 million for contingent consideration related net sales royalties and milestones. As a result of our quarterly valuation update process during 2016 and 2017, the contingent liability was decreased by $2.3 million and $5.7 million, respectively, and increased by $1.0 million during 2018. The resulting balance of the L-UDCA contingent liability at December 31, 2018 was $18.0 million. During the first quarter of 2019, the Company elected to discontinue development of the L-UDCA program, resulting in the write off of the intangible asset of $25.5 million originally recorded in 2016, and the reversal of associated contingent consideration of $18.0 million. This resulted in a net $7.5 million non-cash charge to first quarter operations. In August 2019, following a strategic review of the CNSA-001 program in patients with PKU, the Company made the decision to decline to exercise its option to acquire Censa Pharmaceuticals and accordingly discontinue its joint development program for CNSA-001. The Company impaired the related $15 million long term investment during the third quarter of 2019. See Note 5 of the Consolidated Financial Statements for further discussion.

INTANGIBLE ASSETS - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Jun. 30, 2016
Finite-Lived Intangible Assets [Line Items]
Net book value of amortizable intangible assets	$ 157,799			$ 157,799		$ 186,691
Impairment of L-UDCA IPR&D intangible asset	0	$ 25,500	$ 0	25,500	$ 0
IPR&D asset	$ 241,195			$ 241,195		255,643
Acquired Product Rights L-UDCA
Finite-Lived Intangible Assets [Line Items]
Impairment of L-UDCA IPR&D intangible asset		$ 25,500
IPR&D asset						$ 25,500	$ 25,500

CONVERTIBLE NOTES PAYABLE - Schedule of Interest Expense (Details) - Senior Notes - Senior Notes Due 2025 - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Debt Instrument [Line Items]
Contractual interest expense	$ 1,725	$ 383	$ 5,175	$ 383
Amortization of debt discount	2,239	468	6,591	468
Amortization of debt issuance costs	224	50	672	50
Total interest expense for the 2025 Notes	$ 4,188	$ 901	$ 12,438	$ 901

ACCRUED EXPENSES (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Payables and Accruals [Abstract]
Government rebates payable	$ 5,934	$ 8,464
Compensation related costs	13,490	10,446
Accrued royalties and contingent consideration	6,888	6,805
Research and development	16,300	16,515
Selling, general and administrative	3,593	2,990
Miscellaneous accrued	1,669	4,475
Total accrued expenses	$ 47,874	$ 49,695

FAIR VALUE MEASUREMENTS - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended		12 Months Ended
	Sep. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Sep. 10, 2018
Business Acquisition [Line Items]
Change in fair value of contingent consideration	$ (702)		$ 16,601	$ 5,820	$ 22,387
Write off of L-UDCA contingent consideration	$ 0	$ 18,000	$ 0	18,000	0
Adjustments to contingent consideration				(4,329)	(6,852)	$ 1,000	$ (5,700)	$ (2,300)
Product Rights Chenodal
Business Acquisition [Line Items]
Change in fair value of contingent consideration				6,900
Adjustments to contingent consideration					10,000
Acquired Product Rights Cholbam
Business Acquisition [Line Items]
Change in fair value of contingent consideration				$ (1,100)
Adjustments to contingent consideration					10,400
Acquired Product Rights L-UDCA
Business Acquisition [Line Items]
Adjustments to contingent consideration					$ 2,000
Senior Notes \| Senior Notes Due 2025
Business Acquisition [Line Items]
Interest rate percentage	2.50%			2.50%					2.50%
Fair value of convertible debt	$ 206,700			$ 206,700

SHARE BASED COMPENSATION - Stock Option Activity (Details) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2019 USD ($) $ / shares shares	Dec. 31, 2018 USD ($) $ / shares shares
Weighted Average Exercise Price
Number of shares exercisable (in shares) \| shares	4,900,000
Weighted average exercise price (in dollars per share) \| $ / shares	$ 18.80
Stock Options
Shares Underlying Options
Beginning balance (in shares) \| shares	7,277,337
Granted (in shares) \| shares	1,222,225
Exercised (in shares) \| shares	(75,527)
Forfeited/canceled (in shares) \| shares	(959,444)
Ending balance (in shares) \| shares	7,464,591	7,277,337
Weighted Average Exercise Price
Beginning balance (in dollars per share) \| $ / shares	$ 18.55
Granted (in dollars per share) \| $ / shares	20.01
Exercised (in dollars per share) \| $ / shares	12.49
Forfeited/canceled (in dollars per share) \| $ / shares	12.31
Ending balance (in dollars per share) \| $ / shares	$ 19.65	$ 18.55
Weighted Average Remaining Contractual Life (years)	6 years 7 months 20 days	6 years 11 months 8 days
Aggregate Intrinsic Value \| $	$ 1,202	$ 40,650
Unamortized stock compensation expense \| $	$ 30,100
Weighted-average recognition period (in years)	2 years 8 months 12 days

COMMITMENTS AND CONTINGENCIES	9 Months Ended
COMMITMENTS AND CONTINGENCIES	Sep. 30, 2019
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES Research Collaboration and Licensing Agreements As part of the Company's research and development efforts, the Company enters into research collaboration and licensing agreements with unrelated companies, scientific collaborators, universities, and consultants. These agreements contain varying terms and provisions which include fees and milestones to be paid by the Company, services to be provided, and ownership rights to certain proprietary technology developed under the agreements. Some of these agreements contain provisions which require the Company to pay royalties, in the event the Company sells or licenses any proprietary products developed under the respective agreements. Legal Proceedings In August 2017, Martin Shkreli, the Company’s former Chief Executive Officer, was convicted on securities fraud charges following investigations by the U.S. Attorney for the Eastern District of New York and the U.S. Securities and Exchange Commission. Mr. Shkreli appealed his conviction to the United States Court of Appeals for the Second Circuit, and in July 2019, the Court of Appeals affirmed his conviction. In connection with the trial and appeal proceedings, the Company advanced a portion of Mr. Shkreli’s legal fees, of which $3.8 million was reimbursed by its directors’ and officers’ insurance carriers. Pending the outcome of Mr. Shkreli's appeal, the insurance carriers reserved their rights to assert that certain of the advanced funds pertain to claims excluded from coverage under the relevant insurance policy and are therefore recoverable by the carriers, and therefore the final amount of the reimbursement from the insurance carriers is not currently estimable. In October 2018, Spring Pharmaceuticals, LLC (Spring) filed a lawsuit against the Company, Martin Shkreli, Mission Pharmacal Company and Alamo Pharma Services, Inc. in the United States District Court for the Eastern District of Pennsylvania alleging that the Company violated various federal and state antitrust and unfair competition laws by allegedly refusing to sell samples of the Thiola® brand drug so that Spring can conduct the bioequivalence testing needed to submit an ANDA to the FDA for approval to market a generic version of the product. Spring is seeking injunctive relief and damages. The Company intends to vigorously defend against Spring’s claims. In January 2019, the Company filed a motion to dismiss the lawsuit. In April 2019, the Court stayed the Company's motion to dismiss to allow for discovery limited to the question of whether Spring has standing to sue. That discovery has been completed and the Company is awaiting the Court’s decision on the motion to dismiss. No amounts have been accrued related to this matter and the outcome cannot be determined. The Company is not aware of any other proceedings or claims that could have, individually or in the aggregate, a material adverse effect on its results of operations or financial condition.

Label	Element	Value
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 15,710,000
Additional Paid-in Capital [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	5,394,000
Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 10,316,000

FAIR VALUE MEASUREMENTS - Assets and Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2017	Jun. 30, 2016
Assets:
Cash and Cash Equivalents	$ 65,188	$ 102,873	$ 154,820	$ 99,394
Marketable securities, available-for-sale	341,835	368,668
Total	407,023	471,541
Liabilities:
Business combination-related contingent consideration	73,900	93,000			$ 25,000
Total	73,900	93,000
Quoted prices in active markets (Level 1)
Assets:
Cash and Cash Equivalents	65,188	62,978
Marketable securities, available-for-sale	0	0
Total	65,188	62,978
Liabilities:
Business combination-related contingent consideration	0	0
Total	0	0
Significant other observable inputs (Level 2)
Assets:
Cash and Cash Equivalents	0	39,895
Marketable securities, available-for-sale	341,835	368,668
Total	341,835	408,563
Liabilities:
Business combination-related contingent consideration	0	0
Total	0	0
Significant unobservable inputs (Level 3)
Assets:
Cash and Cash Equivalents	0	0
Marketable securities, available-for-sale	0	0
Total	0	0
Liabilities:
Business combination-related contingent consideration	73,900	93,000
Total	$ 73,900	$ 93,000

FAIR VALUE MEASUREMENTS

9 Months Ended

Sep. 30, 2019

Fair Value Disclosures [Abstract]

FAIR VALUE MEASUREMENTS

Financial Instruments and Fair Value

The Company accounts for financial instruments in accordance with ASC 820, Fair Value Measurements and Disclosures (“ASC 820”). ASC 820 establishes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to unobservable inputs (Level 3 measurements). The three levels of the fair value hierarchy under ASC 820 are described below:

Level 1 – Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities;

Level 2 – Quoted prices in markets that are not active or financial instruments for which all significant inputs are observable, either directly or indirectly; and

Level 3 – Prices or valuations that require inputs that are both significant to the fair value measurement and unobservable.

The valuation techniques used to measure the fair value of the Company’s marketable securities and all other financial instruments, all of which have counter-parties with high credit ratings, were valued based on quoted market prices or model driven valuations using significant inputs derived from or corroborated by observable market data. Based on the fair value hierarchy, the Company classified marketable securities within Level 2.

In estimating the fair value of the Company’s contingent consideration, the Company used the Monte Carlo Simulation model as of September 30, 2019 and December 31, 2018. Based on the fair value hierarchy, the Company classified the fair value measurement of contingent consideration within Level 3.

Financial instruments with carrying values approximating fair value include cash and cash equivalents, accounts receivable, and accounts payable, due to their short-term nature. As of September 30, 2019, the estimated fair value of the Company's 2.5% Convertible Senior Notes due 2025 was $206.7 million, considering factors such as market conditions, prepayment and make-whole provisions, variability in pricing from multiple lenders and the term of the debt.

The following table presents the Company’s assets and liabilities, measured and recognized at fair value on a recurring basis, classified under the appropriate level of the fair value hierarchy as of September 30, 2019 (in thousands):



	As of September 30, 2019
	Total carrying and estimated fair value		Quoted prices in active markets (Level 1)		Significant other observable inputs (Level 2)		Significant unobservable inputs (Level 3)
Assets:
Cash and Cash Equivalents	$	65,188	$	65,188	$	—	$	—
Marketable securities, available-for-sale	341,835		—		341,835		—
Total	$	407,023	$	65,188	$	341,835	$	—
Liabilities:
Business combination-related contingent consideration	$	73,900	$	—	$	—	$	73,900
Total	$	73,900	$	—	$	—	$	73,900



	As of December 31, 2018
	Total carrying and estimated fair value		Quoted prices in active markets (Level 1)		Significant other observable inputs (Level 2)		Significant unobservable inputs (Level 3)
Assets:
Cash and Cash Equivalents	$	102,873	$	62,978	$	39,895	$	—
Marketable securities, available-for-sale	368,668		—		368,668		—
Total	$	471,541	$	62,978	$	408,563	$	—
Liabilities:
Business combination-related contingent consideration	93,000		—		—		93,000
Total	$	93,000	$	—	$	—	$	93,000

The following table sets forth a summary of changes in the estimated fair value of the Company's business combination-related contingent consideration for the nine months ended September 30, 2019 (in thousands):



	Fair Value Measurements of Acquisition-Related Contingent Consideration (Level 3)
Balance at January 1, 2019	$	93,000
L-UDCA write-off	(18,000		)
Changes in the fair value of contingent consideration	5,820
Contractual payments included in accrued liabilities at September 30, 2019	(2,245		)
Contractual payments	(4,556		)
Foreign currency impact	(119		)
Balance at September 30, 2019	$	73,900

The key assumptions included in the calculations for contingent consideration were the future number of patients in treatment, projected revenues, discount rate, and the timing of payments. The present value of the expected payments considers the time at which the obligations are expected to be settled and a discount rate that reflects the risk associated with the performance payments.

During the three and nine months ended September 30, 2019, the Company recognized $(0.7) million and $5.8 million, respectively, in operating expense on the Condensed Consolidated Statement of Operations and Comprehensive Loss for the change in fair value of the contingent consideration liabilities. For the nine months ended September 30, 2019, $6.9 million and $(1.1) million of the charges were related to the change in contingent consideration liabilities for the products Chenodal and Cholbam, respectively. In each case, the value increased due to passage of time and projected revenues. During the first quarter of 2019, the Company made a portfolio decision not to pursue further development of its product candidate L-UDCA. The related contingent consideration of $18.0 million was accordingly fully written off. See Note 17 for further discussion.

During the three and nine months ended September 30, 2018, the Company incurred charges of $16.6 million and $22.4 million, respectively, in operating expenses on the Condensed Consolidated Statements of Operations and Comprehensive Loss for the change in fair value of the

contingent consideration liabilities. For the nine months ended September 30, 2018, $10.0 million, $10.4 million, and $2.0 million of the charges were related to the increase in contingent consideration liabilities for the products Chenodal and Cholbam and product candidate L-UDCA, respectively. In each case, the value increased due to passage of time.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

INVENTORY

9 Months Ended

Sep. 30, 2019

Inventory Disclosure [Abstract]

INVENTORY

Inventory, net of reserves, consisted of the following at September 30, 2019 and December 31, 2018 (in thousands):



	September 30, 2019		December 31, 2018
Raw materials	$	3,078	$	4,689
Finished goods	2,186		930
Total inventory	$	5,264	$	5,619

The inventory reserve was $2.4 million and $1.8 million at September 30, 2019 and December 31, 2018, respectively.

INTANGIBLE ASSETS

9 Months Ended

Sep. 30, 2019

Goodwill and Intangible Assets Disclosure [Abstract]

INTANGIBLE ASSETS

As of September 30, 2019, the net book value of amortizable intangible assets was approximately $157.8 million.

The following table sets forth amortizable intangible assets as of September 30, 2019 and December 31, 2018 (in thousands):



	September 30, 2019			December 31, 2018
Finite-lived intangible assets	$	241,195		$	255,643
Less: accumulated amortization	(83,396		)	(68,952		)
Net carrying value	$	157,799		$	186,691

During the first quarter of 2019, the Company made a portfolio decision not to pursue further development of L-UDCA, acquired in 2016. The related in-progress research and development intangible asset ("IPR&D") of $25.5 million was accordingly considered fully impaired and written off. As of December 31, 2018, the value of the IPR&D was $25.5 million. See Note 17 for further discussion.

The following table summarizes amortization expense for the three and nine months ended September 30, 2019 and 2018 (in thousands):



	Three Months Ended September 30,				Nine Months Ended September 30,
	2019		2018		2019		2018
Research and development	$	292	$	292	$	866	$	684
Selling, general and administrative	4,715		4,333		13,728		12,635
Total amortization expense	$	5,007	$	4,625	$	14,594	$	13,319

CONVERTIBLE NOTES PAYABLE - Composition of Notes (Details) - Senior Notes - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Sep. 10, 2018
Senior Notes Due 2025
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	2.50%		2.50%
Long-term Debt, Gross	$ 276,000	$ 276,000
Unamortized debt discount	(68,245)	(74,836)
Unamortized debt issuance costs	(5,400)	(6,073)
Long-term Debt	$ 202,355	195,091
Convertible Notes Due 2019
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage	4.50%
Long-term Debt, Gross		22,590
Unamortized debt discount		(125)
Unamortized debt issuance costs		(8)
Long-term Debt		$ 22,457

MARKETABLE SECURITIES - Additional Information (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Investments, Debt and Equity Securities [Abstract]
Proceeds from the sale/maturity of marketable securities	$ 180,818	$ 96,166
Purchases of debt based marketable securities	$ (150,950)	$ (219,820)

INCOME TAXES (Tables)

9 Months Ended

Sep. 30, 2019

Income Tax Disclosure [Abstract]

Schedule of components of income tax (expense) benefit

The following table summarizes our effective tax rate and income tax expense for the three and nine months ended September 30, 2019 and 2018 (dollars in millions):



	Three Months Ended September 30,						Nine Months Ended September 30,
	2019			2018			2019			2018
Effective tax rate	1.4		%	(0.8		)%	—		%	(0.9		)%
Income tax benefit (expense)	$	0.5		$	(0.4	)	$	0.1		$	(0.8	)

MARKETABLE SECURITIES - Available for Sale Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, amortized cost basis, current	$ 230,364	$ 209,137
Debt securities available for sale, unrealized gain, current	565	0
Debt securities available for sale unrealized loss, current	(18)	(662)
Debt securities, available-for-sale, current	230,911	208,475
Debt securities, available-for-sale, amortized cost basis, noncurrent	110,393	160,810
Debt securities, available for sale unrealized gain, noncurrent	598	22
Debt securities available for sale unrealized gain loss, noncurrent	(67)	(639)
Debt securities, available-for-sale, noncurrent	110,924	160,193
Debt securities, available-for-sale, amortized cost	340,757	369,947
Debt securities, available for sale, unrealized gains	1,163	22
Debt securities, available-for-sale, unrealized gain (loss)	(85)	(1,301)
Aggregate Estimated Fair Value	341,835	368,668
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, amortized cost basis, current	43,479	59,313
Debt securities available for sale, unrealized gain, current	28	0
Debt securities available for sale unrealized loss, current	(3)	(58)
Debt securities, available-for-sale, current	43,504	59,255
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, amortized cost basis, current	186,885	149,824
Debt securities available for sale, unrealized gain, current	537	0
Debt securities available for sale unrealized loss, current	(15)	(604)
Debt securities, available-for-sale, current	187,407	149,220
Debt securities, available-for-sale, amortized cost basis, noncurrent	99,216	150,813
Debt securities, available for sale unrealized gain, noncurrent	598	18
Debt securities available for sale unrealized gain loss, noncurrent	(33)	(638)
Debt securities, available-for-sale, noncurrent	99,781	150,193
Securities of government sponsored entities
Debt Securities, Available-for-sale [Line Items]
Debt securities, available-for-sale, amortized cost basis, noncurrent	11,177	9,997
Debt securities, available for sale unrealized gain, noncurrent	0	4
Debt securities available for sale unrealized gain loss, noncurrent	(34)	(1)
Debt securities, available-for-sale, noncurrent	$ 11,143	$ 10,000

Document and Entity Information - shares	9 Months Ended
Document and Entity Information - shares	Sep. 30, 2019	Oct. 29, 2019
Cover page.
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2019
Document Transition Report	false
Entity File Number	001-36257
Entity Registrant Name	RETROPHIN, INC.
Entity Central Index Key	0001438533
Current Fiscal Year End Date	--12-31
Amendment Flag	false
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	27-4842691
Entity Address, Address Line One	3721 Valley Centre Drive
Entity Address, Address Line Two	Suite 200
Entity Address, City or Town	San Diego
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	92130
City Area Code	888
Local Phone Number	969-7879
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Trading Symbol	RTRX
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		42,958,401

ACCRUED EXPENSES (Tables)

9 Months Ended

Sep. 30, 2019

Payables and Accruals [Abstract]

Schedule of Accrued Expenses

Accrued expenses at September 30, 2019 and December 31, 2018 consisted of the following (in thousands):



	September 30, 2019		December 31, 2018
Government rebates payable	$	5,934	$	8,464
Compensation related costs	13,490		10,446
Accrued royalties and contingent consideration	6,888		6,805
Research and development	16,300		16,515
Selling, general and administrative	3,593		2,990
Miscellaneous accrued	1,669		4,475
Total accrued expenses	$	47,874	$	49,695

INCOME TAXES

9 Months Ended

Sep. 30, 2019

Income Tax Disclosure [Abstract]

INCOME TAXES

The following table summarizes our effective tax rate and income tax expense for the three and nine months ended September 30, 2019 and 2018 (dollars in millions):



	Three Months Ended September 30,						Nine Months Ended September 30,
	2019			2018			2019			2018
Effective tax rate	1.4		%	(0.8		)%	—		%	(0.9		)%
Income tax benefit (expense)	$	0.5		$	(0.4	)	$	0.1		$	(0.8	)

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Sep. 30, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized (in shares)	20,000,000	20,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock shares authorized (in shares)	100,000,000	100,000,000
Common stock shares issued (in shares)	42,958,401	41,389,524
Common stock shares outstanding (in shares)	42,958,401	41,389,524

DESCRIPTION OF BUSINESS

9 Months Ended

Sep. 30, 2019

Organization, Consolidation and Presentation of Financial Statements [Abstract]

DESCRIPTION OF BUSINESS

Organization and Description of Business

Retrophin, Inc. (“we”, “our”, “us”, “Retrophin” and the “Company”) refers to Retrophin, Inc., a Delaware corporation, as well as our direct and indirect subsidiaries. Retrophin is a biopharmaceutical company headquartered in San Diego, California, focused on identifying, developing and delivering life-changing therapies to people living with rare diseases. We regularly evaluate and, where appropriate, act on opportunities to expand our product pipeline through licenses and acquisitions of products in areas that will serve patients with rare diseases and that we believe offer attractive growth characteristics.

Product Candidate Development Activities:

Sparsentan, also known as RE-021, is an investigational product candidate with a dual mechanism of action, a potent angiotensin receptor blocker (“ARB”) and selective endothelin receptor antagonist (“ERA”), with in vitro selectivity toward endothelin receptor type A. Sparsentan is currently being evaluated in two pivotal Phase 3 clinical studies in the following indications:


•	Focal segmental glomerulosclerosis ("FSGS") is a rare kidney disease characterized by proteinuria where the glomeruli become progressively scarred. FSGS is a leading cause of end-stage renal disease.


•	Immunoglobulin A nephropathy ("IgAN") is an immune-complex-mediated glomerulonephritis characterized by hematuria, proteinuria, and variable rates of progressive renal failure. IgAN is the most common primary glomerular disease.

The Company has three approved products:


•	Chenodal (chenodiol tablets) is approved in the United States for the treatment of patients suffering from gallstones in whom surgery poses an unacceptable health risk due to disease or advanced age. Chenodal has been the standard of care for cerebrotendinous xanthomatosis ("CTX") patients for more than three decades and the Company is currently pursuing adding this indication to the label.


•	Cholbam (cholic acid capsules) is approved in the United States for the treatment of bile acid synthesis disorders due to single enzyme defects and is further indicated for adjunctive treatment of patients with peroxisomal disorders.

•

Thiola (tiopronin tablets) is approved in the United States for the prevention of cystine (kidney) stone formation in patients with severe homozygous cystinuria. On June 28, 2019, the Company announced that the U.S. Food and Drug Administration ("FDA") approved 100 mg and 300 mg tablets of THIOLA EC™ (tiopronin), a new enteric-coated formulation of THIOLA® (tiopronin), to be used for the treatment of cystinuria.

Cooperative Research and Development Agreements ("CRADAs"):

The Company is a participant in two CRADAs, which form a multi-stakeholder approach to pool resources with leading experts, and incorporates the patient perspective early in the identification and development process. Retrophin has partnered with the National Institutes of Health’s National Center for Advancing Translational Sciences ("NCATS") and leading patients advocacy organization, NGLY1.org and Alagille Syndrome Alliance ("ALGSA"), aimed at the identification of potential small molecule therapeutics for NGLY1 deficiency, and Alagille syndrome respectively, diseases with no approved treatment options.

Changes in Development Activities:

In August 2019, the Company announced that the Phase 3 FORT Study evaluating the safety and efficacy of fosmetpantotenate compared to placebo in patients with pantothenate kinase-associated neurodegeneration ("PKAN") did not meet its primary endpoint and did not demonstrate a difference between treatment groups. The study also did not meet its secondary endpoint. The Company will not proceed with further development of fosmetpantotenate for PKAN.

In August 2019, following a strategic review of the CNSA-001 program in patients with phenylketonuria ("PKU"), the Company made the decision to decline to exercise its option to acquire Censa Pharmaceuticals and accordingly discontinue its joint development program for CNSA-001. The Company impaired the related $15 million long term investment during the third quarter of 2019.

During the first quarter of 2019, the Company elected to discontinue development of the L-UDCA program, resulting in impairment of the intangible asset of $25.5 million, originally recorded in 2016, and the related $18.0 million in contingent liability. This resulted in a net $7.5 million non-cash charge to first quarter operations. In June 2016, the Company acquired certain rights to its product candidate L-UDCA for $0.5 million cash. At the same time the Company established a related non-cash asset of $25.5 million and liability of $25.0 million for IPR&D and contingent consideration (deferred financing) related net sales royalties and milestones. As a result of our quarterly valuation update process during 2016 and 2017, the contingent liability was decreased by $2.3 million and $5.7 million, respectively, and increased by $1.0 million during 2018. The resulting balance of the L-UDCA contingent liability at December 31, 2018 was $18.0 million.

REVENUE RECOGNITION (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
REVENUE RECOGNITION (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	$ 44,373	$ 40,706	$ 128,651	$ 120,475
Bile acid products
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	19,938	18,052	59,258	55,153
Tiopronin products
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	$ 24,435	$ 22,654	$ 69,393	$ 65,322
Geographic Concentration Risk \| Revenue from Contract with Customer \| United States
Disaggregation of Revenue [Line Items]
Concentration risk, percentage			95.00%

REVENUE RECOGNITION (Tables)

9 Months Ended

Sep. 30, 2019

Revenue from Contract with Customer [Abstract]

Summary of net product revenue

The following table summarizes net product revenues for the three and nine months ended September 30, 2019 and 2018 (in thousands):



	Three Months Ended September 30,				Nine Months Ended September 30,
	2019		2018		2019		2018
Bile acid products	$	19,938	$	18,052	$	59,258	$	55,153
Tiopronin products	24,435		22,654		69,393		65,322
Total net product revenue	$	44,373	$	40,706	$	128,651	$	120,475

SHARE BASED COMPENSATION (Tables)

9 Months Ended

Sep. 30, 2019

Equity [Abstract]

Schedule of service based restricted stock activity

The following table summarizes the Company’s service based restricted stock unit activity during the nine months ended September 30, 2019:



	Number of Restricted Stock Units		Weighted Average Grant Date Fair Value
Unvested December 31, 2018	400,426		$	24.95
Granted	419,265		18.73
Vested	(132,203	)	24.42
Forfeited/canceled	(30,802	)	22.06
Unvested September 30, 2019	656,686		$	21.23

Schedule of performance based restricted stock activity

The following table summarizes the Company’s performance based restricted stock unit activity during the nine months ended September 30, 2019:



	Number of Restricted Stock Units		Weighted Average Grant Date Fair Value
Unvested December 31, 2018	226,750		$	21.54
Granted	80,000		21.32
Vested	—		—
Forfeited/canceled	(73,250	)	23.33
Unvested September 30, 2019	233,500		$	20.90

Schedule of stock option issuances and balances outstanding

The following table summarizes stock option activity during the nine months ended September 30, 2019:



	Shares Underlying Options		Weighted Average Exercise Price	Weighted Average Remaining Contractual Life (years)	Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2018	7,277,337		$18.55	6.94	$	40,650
Granted	1,222,225		$20.01
Exercised	(75,527	)	$12.49
Forfeited/canceled	(959,444	)	$12.31
Outstanding at September 30, 2019	7,464,591		$19.65	6.64	$	1,202

Schedule of share based compensation expenses

The following table sets forth total share-based compensation for the three and nine months ended September 30, 2019 and 2018 (in thousands):



	Three Months Ended September 30,				Nine Months Ended September 30,
	2019		2018		2019		2018
Research and development	$	1,735	$	1,603	$	5,301	$	4,592
Selling, general & administrative	2,605		3,282		11,307		10,328
Total	$	4,340	$	4,885	$	16,608	$	14,920

LOSS PER COMMON SHARE

9 Months Ended

Sep. 30, 2019

Earnings Per Share [Abstract]

LOSS PER COMMON SHARE

Basic and diluted net loss per common share is calculated by dividing net loss applicable to common stockholders by the weighted-average number of common shares outstanding during the period, without consideration of common stock equivalents. The Company’s potentially dilutive shares, which include outstanding stock options, restricted stock units, warrants, and shares issuable upon conversion of the 2019 Notes and 2025 Notes, are considered to be common stock equivalents and are only included in the calculation of diluted net loss per share when their effect is dilutive.

Basic and diluted net loss per share is calculated as follows (net loss amounts are stated in thousands):



	Three Months Ended September 30,
	2019							2018
	Shares	Net Loss			EPS			Shares	Net Loss			EPS
Basic and diluted loss per share	42,943,828	$	(36,490	)	$	(0.85	)	40,717,440	$	(54,516	)	$	(1.34	)



	Nine Months Ended September 30,
	2019							2018
	Shares	Net Loss			EPS			Shares	Net Loss			EPS
Basic and diluted loss per share	42,109,618	$	(116,168	)	$	(2.76	)	40,149,184	$	(95,223	)	$	(2.37	)

The following common stock equivalents have been excluded because they were anti-dilutive (in thousands):



	Three Months Ended September 30,		Nine Months Ended September 30,
	2019	2018	2019	2018
Restricted stock units	809	477	704	335
Convertible debt	7,113	8,411	7,805	8,411
Options	7,527	7,390	7,709	7,202
Warrants	—	40	—	377
Total anti-dilutive shares	15,449	16,318	16,218	16,325

MARKETABLE SECURITIES (Tables)

9 Months Ended

Sep. 30, 2019

Investments, Debt and Equity Securities [Abstract]

Schedule of marketable securities

Marketable securities consisted of the following (in thousands):



	September 30, 2019		December 31, 2018
Commercial paper	$	43,504	$	59,255
Corporate debt securities	287,188		299,413
Securities of government sponsored entities	11,143		10,000
Total marketable securities:	$	341,835	$	368,668

Debt securities available for sale

The following is a summary of short-term marketable securities classified as available-for-sale as of September 30, 2019 (in thousands):



	Remaining Contractual Maturity (in years)	Amortized Cost		Unrealized Gains		Unrealized Losses			Aggregate Estimated Fair Value
Commercial paper	Less than 1	$	43,479	$	28	$	(3	)	$	43,504
Corporate debt securities	Less than 1	186,885		537		(15		)	187,407
Total maturity less than 1 year		230,364		565		(18		)	230,911
Corporate debt securities	1 to 2	99,216		598		(33		)	99,781
Securities of government-sponsored entities	1 to 2	11,177		—		(34		)	11,143
Total maturity 1 to 2 years		110,393		598		(67		)	110,924
Total available-for-sale securities		$	340,757	$	1,163	$	(85	)	$	341,835

The following is a summary of short-term marketable securities classified as available-for-sale as of December 31, 2018 (in thousands):



	Remaining Contractual Maturity (in years)	Amortized Cost		Unrealized Gains		Unrealized Losses			Aggregate Estimated Fair Value
Commercial paper	Less than 1	$	59,313	$	—	$	(58	)	$	59,255
Corporate debt securities	Less than 1	149,824		—		(604		)	149,220
Total maturity less than 1 year		209,137		—		(662		)	208,475
Corporate debt securities	1 to 2	150,813		18		(638		)	150,193
Securities of government-sponsored entities	1 to 2	9,997		4		(1		)	10,000
Total maturity 1 to 2 years		160,810		22		(639		)	160,193
Total available-for-sale securities		$	369,947	$	22	$	(1,301	)	$	368,668

ACCRUED EXPENSES

9 Months Ended

Sep. 30, 2019

Payables and Accruals [Abstract]

ACCRUED EXPENSES

Accrued expenses at September 30, 2019 and December 31, 2018 consisted of the following (in thousands):



	September 30, 2019		December 31, 2018
Government rebates payable	$	5,934	$	8,464
Compensation related costs	13,490		10,446
Accrued royalties and contingent consideration	6,888		6,805
Research and development	16,300		16,515
Selling, general and administrative	3,593		2,990
Miscellaneous accrued	1,669		4,475
Total accrued expenses	$	47,874	$	49,695

ACCOUNTS RECEIVABLE	9 Months Ended
ACCOUNTS RECEIVABLE	Sep. 30, 2019
Receivables [Abstract]
ACCOUNTS RECEIVABLE	ACCOUNTS RECEIVABLE Accounts receivable, net of reserves for prompt pay discounts and doubtful accounts, was $16.8 million and $12.7 million at September 30, 2019 and December 31, 2018, respectively. The total reserves for both periods were immaterial.

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Statement [Abstract]
Net product sales	$ 44,373	$ 40,706	$ 128,651	$ 120,475
Operating expenses:
Cost of goods sold	1,513	1,133	3,509	3,924
Research and development	33,220	32,448	104,597	91,544
Selling, general and administrative	29,779	26,107	101,418	77,675
Change in fair value of contingent consideration	(702)	16,601	5,820	22,387
Impairment of L-UDCA IPR&D intangible asset	0	0	25,500	0
Write off of L-UDCA contingent consideration	0	0	(18,000)	0
Impairment of long-term investment	15,000	0	15,000	0
Total operating expenses	78,810	76,289	237,844	195,530
Operating loss	(34,437)	(35,583)	(109,193)	(75,055)
Other income (expenses), net:
Other expense, net	(496)	(90)	(673)	(372)
Interest income	2,467	1,147	7,875	2,905
Interest expense	(4,547)	(2,533)	(14,230)	(4,848)
Loss on early extinguishment of debt	0	(17,042)	0	(17,042)
Total other expense, net	(2,576)	(18,518)	(7,028)	(19,357)
Loss before income taxes	(37,013)	(54,101)	(116,221)	(94,412)
Income tax benefit (expense)	523	(415)	53	(811)
Net loss	$ (36,490)	$ (54,516)	$ (116,168)	$ (95,223)
Basic and diluted net loss per common share (in dollars/share)	$ (0.85)	$ (1.34)	$ (2.76)	$ (2.37)
Basic and diluted weighted average common shares outstanding (in shares)	42,943,828	40,717,440	42,109,618	40,149,184
Comprehensive loss:
Net loss	$ (36,490)	$ (54,516)	$ (116,168)	$ (95,223)
Foreign currency translation	315	5	342	29
Unrealized gain (loss) on marketable securities	75	64	2,359	(97)
Comprehensive loss	$ (36,100)	$ (54,447)	$ (113,467)	$ (95,291)

LOSS PER COMMON SHARE - Antidilutive Shares (Details) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive shares excluded from the calculation	15,449	16,318	16,218	16,325
Restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive shares excluded from the calculation	809	477	704	335
Convertible debt
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive shares excluded from the calculation	7,113	8,411	7,805	8,411
Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive shares excluded from the calculation	7,527	7,390	7,709	7,202
Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive shares excluded from the calculation	0	40	0	377

SHARE BASED COMPENSATION

9 Months Ended

Sep. 30, 2019

Equity [Abstract]

SHARE BASED COMPENSATION

Restricted Shares

Service Based Restricted Stock Units

The following table summarizes the Company’s service based restricted stock unit activity during the nine months ended September 30, 2019:



	Number of Restricted Stock Units		Weighted Average Grant Date Fair Value
Unvested December 31, 2018	400,426		$	24.95
Granted	419,265		18.73
Vested	(132,203	)	24.42
Forfeited/canceled	(30,802	)	22.06
Unvested September 30, 2019	656,686		$	21.23

At September 30, 2019, unamortized stock compensation for service based restricted stock units was $11.9 million, with a weighted-average recognition period of 3.1 years.

Performance Based Restricted Stock Units

The following table summarizes the Company’s performance based restricted stock unit activity during the nine months ended September 30, 2019:



	Number of Restricted Stock Units		Weighted Average Grant Date Fair Value
Unvested December 31, 2018	226,750		$	21.54
Granted	80,000		21.32
Vested	—		—
Forfeited/canceled	(73,250	)	23.33
Unvested September 30, 2019	233,500		$	20.90

At September 30, 2019, unamortized stock compensation for performance based restricted stock units was $0.7 million, with a weighted-average recognition period of 1.0 years.

Stock Options

The following table summarizes stock option activity during the nine months ended September 30, 2019:



	Shares Underlying Options		Weighted Average Exercise Price	Weighted Average Remaining Contractual Life (years)	Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2018	7,277,337		$18.55	6.94	$	40,650
Granted	1,222,225		$20.01
Exercised	(75,527	)	$12.49
Forfeited/canceled	(959,444	)	$12.31
Outstanding at September 30, 2019	7,464,591		$19.65	6.64	$	1,202

At September 30, 2019, unamortized stock compensation for stock options was $30.1 million, with a weighted-average recognition period of 2.7 years.

At September 30, 2019, outstanding options to purchase 4.9 million shares of common stock were exercisable with a weighted-average exercise price per share of $18.80.

Share Based Compensation

The following table sets forth total share-based compensation for the three and nine months ended September 30, 2019 and 2018 (in thousands):



	Three Months Ended September 30,				Nine Months Ended September 30,
	2019		2018		2019		2018
Research and development	$	1,735	$	1,603	$	5,301	$	4,592
Selling, general & administrative	2,605		3,282		11,307		10,328
Total	$	4,340	$	4,885	$	16,608	$	14,920

Exercise of Warrants

The Company issued 532,830 and 956,887 shares of common stock upon the exercise of outstanding warrants during the three and nine months ended September 30, 2018, respectively, for cash received by the Company in the amount of $2.1 million and $4.3 million, respectively. As of September 30, 2019 and December 31, 2018, there were no warrants outstanding.

SHARE BASED COMPENSATION - Service Based Restricted Stock Activity (Details) - Restricted stock units $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2019 USD ($) $ / shares shares
Number of Shares
Beginning balance (in shares) \| shares	400,426
Granted (in shares) \| shares	419,265
Vested (in shares) \| shares	(132,203)
Forfeited/canceled (in shares) \| shares	(30,802)
Ending balance (in share) \| shares	656,686
Weighted Average Grant Date Fair Value
Beginning balance (in dollars per share) \| $ / shares	$ 24.95
Granted (in dollars per share) \| $ / shares	18.73
Vested (in dollars per share) \| $ / shares	24.42
Forfeited/canceled (in dollars per share) \| $ / shares	22.06
Ending balance (in dollars per share) \| $ / shares	$ 21.23
Unamortized stock compensation expense \| $	$ 11.9
Weighted-average recognition period (in years)	3 years 1 month 6 days

FAIR VALUE MEASUREMENTS (Tables)

9 Months Ended

Sep. 30, 2019

Fair Value Disclosures [Abstract]

Schedule of fair value on a recurring basis



	As of September 30, 2019
	Total carrying and estimated fair value		Quoted prices in active markets (Level 1)		Significant other observable inputs (Level 2)		Significant unobservable inputs (Level 3)
Assets:
Cash and Cash Equivalents	$	65,188	$	65,188	$	—	$	—
Marketable securities, available-for-sale	341,835		—		341,835		—
Total	$	407,023	$	65,188	$	341,835	$	—
Liabilities:
Business combination-related contingent consideration	$	73,900	$	—	$	—	$	73,900
Total	$	73,900	$	—	$	—	$	73,900



	As of December 31, 2018
	Total carrying and estimated fair value		Quoted prices in active markets (Level 1)		Significant other observable inputs (Level 2)		Significant unobservable inputs (Level 3)
Assets:
Cash and Cash Equivalents	$	102,873	$	62,978	$	39,895	$	—
Marketable securities, available-for-sale	368,668		—		368,668		—
Total	$	471,541	$	62,978	$	408,563	$	—
Liabilities:
Business combination-related contingent consideration	93,000		—		—		93,000
Total	$	93,000	$	—	$	—	$	93,000

Schedule of summary of changes in estimated acquisition related contingent consideration



	Fair Value Measurements of Acquisition-Related Contingent Consideration (Level 3)
Balance at January 1, 2019	$	93,000
L-UDCA write-off	(18,000		)
Changes in the fair value of contingent consideration	5,820
Contractual payments included in accrued liabilities at September 30, 2019	(2,245		)
Contractual payments	(4,556		)
Foreign currency impact	(119		)
Balance at September 30, 2019	$	73,900

REVENUE RECOGNITION

9 Months Ended

Sep. 30, 2019

Revenue from Contract with Customer [Abstract]

REVENUE RECOGNITION

Product Revenue, Net

The Company sells Chenodal and Cholbam (Kolbam), which are aggregated as bile acid products, and Thiola and Thiola EC, aggregated as tiopronin products, through direct-to-patient distributors. The Company sells its products worldwide, with more than 95% of the revenue generated in North America.

Revenues from product sales are recognized when the customer obtains control of the Company’s product, which occurs upon delivery to the customer.

Deductions from Revenue

Revenues from product sales are recorded at the net sales price, which includes provisions resulting from discounts, rebates and co-pay assistance that are offered to customers, health care providers, payors and other indirect customers relating to the Company’s sales of its products. These provisions are based on the amounts earned or to be claimed on the related sales and are classified as a reduction of accounts receivable (if the amount is payable to a customer) or as a current liability (if the amount is payable to a party other than a customer). Where appropriate, these reserves take into consideration the Company’s historical experience, current contractual and statutory requirements, specific known market events and trends, industry data and forecasted customer buying and payment patterns. Overall, these reserves reflect the Company’s best estimates of the amount of consideration to which it is entitled based on the terms of the contract. If actual results in the future vary from the Company’s provisions, the Company will adjust the provision, which would affect net product revenue and earnings in the period such variances become known. Our historical experience is that such adjustments have been immaterial.

Government Rebates: We calculate the rebates that we will be obligated to provide to government programs and deduct these estimated amounts from our gross product sales at the time the revenues are recognized. Allowances for government rebates and discounts are established based on actual payer information, which is reasonably estimated at the time of delivery, and the government-mandated discounts applicable to government-funded programs. Rebate discounts are included in other current liabilities in the accompanying consolidated balance sheets.

Commercial Rebates: We calculate the rebates that we incur due to contracts with certain commercial payors and deduct these amounts from our gross product sales at the time the revenues are recognized. Allowances for commercial rebates are established based on actual payer information, which is reasonably estimated at the time of delivery. Rebate discounts are included in other current liabilities in the accompanying consolidated balance sheets.

Prompt Pay Discounts: We offer discounts to certain customers for prompt payments. We accrue for the calculated prompt pay discount based on the gross amount of each invoice for those customers at the time of sale.

Product Returns: Consistent with industry practice, we offer our customers a limited right to return product purchased directly from the Company, which is principally based upon the product’s expiration date. Generally, shipments are only made upon a patient prescription thus returns are minimal.

Co-pay Assistance: We offer a co-pay assistance program, which is intended to provide financial assistance to qualified commercially insured patients with prescription drug co-payments required by payors. The calculation of the accrual for co-pay assistance is based on an identification of claims and the cost per claim associated with product that has been recognized as revenue.

The following table summarizes net product revenues for the three and nine months ended September 30, 2019 and 2018 (in thousands):



	Three Months Ended September 30,				Nine Months Ended September 30,
	2019		2018		2019		2018
Bile acid products	$	19,938	$	18,052	$	59,258	$	55,153
Tiopronin products	24,435		22,654		69,393		65,322
Total net product revenue	$	44,373	$	40,706	$	128,651	$	120,475

FUTURE ACQUISITION RIGHT AND JOINT DEVELOPMENT AGREEMENT	9 Months Ended
	Sep. 30, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
FUTURE ACQUISITION RIGHT AND JOINT DEVELOPMENT AGREEMENT	FUTURE ACQUISITION RIGHT AND JOINT DEVELOPMENT AGREEMENT Censa Pharmaceuticals Inc. In December 2017, the Company entered into a Future Acquisition Right and Joint Development Agreement (the “Option Agreement”) with Censa, which became effective in January 2018. The Company made an upfront payment of $10.0 million, agreed to fund certain development activities of Censa’s CNSA-001 program which were approximately $19.9 million through proof of concept, and paid $5.0 million related to a development milestone for the right, but not the obligation, to acquire Censa (the “Option”) on the terms and subject to the conditions set forth in a separate Agreement and Plan of Merger. The Company capitalized the upfront and milestone payments and expensed the development funding as incurred. The Company treated the upfront payment and milestone payment, both of which were consideration for the Option, as a cost-method investment with a carrying value of $15.0 million. If the Company had exercised the Option, the Company would have acquired Censa for an additional $65.0 million, which would have been reduced by up to $2.8 million of development funding ("creditable"), paid as a combination of 20% in cash and 80% in shares of the Company’s common stock, valued at a fixed price of $21.40 per share; provided, however, that Censa could have elected on behalf of its equity holders to receive the upfront consideration in 100% cash if the average price per share of the Company’s common stock for the ten trading days ending on the date the Company provided notice of interest to exercise the Option was less than $19.26. In addition, if the Company had exercised the Option and acquired Censa, the Company would have been required to make further cash payments to Censa’s equity holders of up to an aggregate of $25.0 million if the CNSA-001 program had achieved specified development and commercial milestones. The Company determined that Censa was a variable interest entity ("VIE"), and concluded that the Company was not the primary beneficiary of the VIE. As such, the Company did not consolidate Censa’s results into its consolidated financial statements. In August 2019, following a strategic review of the CNSA-001 program in patients with phenylketonuria (PKU), the Company made the decision to decline to exercise its option to acquire Censa Pharmaceuticals and accordingly discontinue its joint development program for CNSA-001. The Company impaired the $15 million long term investment during the current quarter.

COMMITMENTS AND CONTINGENCIES (Details) $ in Millions	1 Months Ended
COMMITMENTS AND CONTINGENCIES (Details) $ in Millions	Aug. 31, 2017 USD ($)
Martin Shkreli
Commitment And Contingency [Line Items]
Legal fees reimbursed from director and officer insurance carriers	$ 3.8

LEASES - Supplemental Balance Sheet Information (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Jan. 01, 2019
Lessee, Lease, Description [Line Items]
Operating lease right-of-use asset	$ 7,347	$ 7,900
Current lease liability	2,668
Noncurrent lease liability	7,807
Total lease liability	10,475	$ 11,300
Prepaid expenses and other current assets
Lessee, Lease, Description [Line Items]
Operating lease right-of-use asset	2,147
Other noncurrent assets
Lessee, Lease, Description [Line Items]
Operating lease right-of-use asset	$ 5,200

INTANGIBLE ASSETS (Tables)

9 Months Ended

Sep. 30, 2019

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of finite-lived amortizable intangible assets

The following table sets forth amortizable intangible assets as of September 30, 2019 and December 31, 2018 (in thousands):



	September 30, 2019			December 31, 2018
Finite-lived intangible assets	$	241,195		$	255,643
Less: accumulated amortization	(83,396		)	(68,952		)
Net carrying value	$	157,799		$	186,691

Schedule of amortization expense

The following table summarizes amortization expense for the three and nine months ended September 30, 2019 and 2018 (in thousands):



	Three Months Ended September 30,				Nine Months Ended September 30,
	2019		2018		2019		2018
Research and development	$	292	$	292	$	866	$	684
Selling, general and administrative	4,715		4,333		13,728		12,635
Total amortization expense	$	5,007	$	4,625	$	14,594	$	13,319

LOSS PER COMMON SHARE - EPS Reconciliation (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Earnings Per Share [Abstract]
Weighted average number of shares outstanding, basic and diluted	42,943,828	40,717,440	42,109,618	40,149,184
Net loss	$ (36,490)	$ (54,516)	$ (116,168)	$ (95,223)
Basic and diluted (in dollars/share)	$ (0.85)	$ (1.34)	$ (2.76)	$ (2.37)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

LEASES (Tables)

9 Months Ended

Sep. 30, 2019

Leases [Abstract]

Schedule of future minimum rent commitments

Following is a schedule of the future minimum rental commitments for our operating lease reconciled to the lease liability and ROU assets as of September 30, 2019 (in thousands):



	September 30, 2019
2019	$	787
2020	2,958
2021	2,486
2022	2,560
2023	2,637
Thereafter	1,585
Total undiscounted future minimum payments	13,013
Present value discount	(2,538		)
Total lease liability	10,475
Lease incentives	(1,543		)
Straight line lease expense in excess of cash payments	(1,585		)
Total ROU asset	$	7,347

Supplemental balance sheet information

As of September 30, 2019, the current and non-current portions of the ROU asset were recorded to the Condensed Consolidated Balance Sheets as follows (in thousands):



	September 30, 2019
Prepaid expenses and other current assets	$	2,147
Other non-current assets	5,200
Total ROU asset	$	7,347

As of September 30, 2019, the current and non-current portions of the lease liability were recorded to the Condensed Consolidated Balance Sheets as follows (in thousands):



	September 30, 2019
Other current liabilities	$	2,668
Other non-current liabilities	7,807
Total lease liabilities	$	10,475

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Beginning balance (in shares) at Dec. 31, 2017		39,373,745
Beginning balance at Dec. 31, 2017	$ 293,134	$ 4	$ 471,800	$ (1,015)	$ (177,655)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share based compensation	14,716		14,716
Issuance of common stock from stock option exercises and vesting of restricted stock units (in shares)		794,149
Issuance of common stock from stock option exercises and vesting of restricted stock units	10,379		10,379
Exercise of warrants (in shares)		956,887
Exercise of warrants	4,274		4,274
Unrealized gain/(loss) on marketable securities	(97)			(97)
Foreign currency translation adjustments	29			29
Issuance of common stock from maturity of the 2019 Convertible debt outstanding	74,945		74,945
ESPP stock purchase and expense (in shares)		43,161
ESPP stock purchase and expense	1,198		1,198
Net loss	(95,223)				(95,223)
Ending balance (in shares) at Sep. 30, 2018		41,167,942
Ending balance at Sep. 30, 2018	319,065	$ 4	582,706	(1,083)	(262,562)
Beginning balance (in shares) at Jun. 30, 2018		40,370,521
Beginning balance at Jun. 30, 2018	287,989	$ 4	497,183	(1,152)	(208,046)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share based compensation	4,801		4,801
Issuance of common stock from stock option exercises and vesting of restricted stock units (in shares)		264,591
Issuance of common stock from stock option exercises and vesting of restricted stock units	3,489		3,489
Exercise of warrants (in shares)		532,830
Exercise of warrants	2,134		2,134
Unrealized gain/(loss) on marketable securities	64			64
Foreign currency translation adjustments	5			5
Issuance of common stock from maturity of the 2019 Convertible debt outstanding	74,945		74,945
ESPP stock purchase and expense	154		154
Net loss	(54,516)				(54,516)
Ending balance (in shares) at Sep. 30, 2018		41,167,942
Ending balance at Sep. 30, 2018	319,065	$ 4	582,706	(1,083)	(262,562)
Beginning balance (in shares) at Dec. 31, 2018		41,389,524
Beginning balance at Dec. 31, 2018	318,253	$ 4	589,795	(1,529)	(270,017)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share based compensation	16,125		16,125
Issuance of common stock from stock option exercises and vesting of restricted stock units (in shares)		207,730
Issuance of common stock from stock option exercises and vesting of restricted stock units	944		944
Unrealized gain/(loss) on marketable securities	2,359			2,359
Foreign currency translation adjustments	342			342
Issuance of common stock from maturity of the 2019 Convertible debt outstanding (in shares)		1,297,343
Issuance of common stock from maturity of the 2019 Convertible debt outstanding	22,590		22,590
ESPP stock purchase and expense (in shares)		63,804
ESPP stock purchase and expense	1,512		1,512
Net loss	(116,168)				(116,168)
Ending balance (in shares) at Sep. 30, 2019		42,958,401
Ending balance at Sep. 30, 2019	245,957	$ 4	630,966	1,172	(386,185)
Beginning balance (in shares) at Jun. 30, 2019		42,899,318
Beginning balance at Jun. 30, 2019	277,089	$ 4	625,999	781	(349,695)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share based compensation	4,178		4,178
Issuance of common stock from stock option exercises and vesting of restricted stock units (in shares)		59,083
Issuance of common stock from stock option exercises and vesting of restricted stock units	627		627
Unrealized gain/(loss) on marketable securities	76			76
Foreign currency translation adjustments	315			315
ESPP stock purchase and expense	162		162
Net loss	(36,490)				(36,490)
Ending balance (in shares) at Sep. 30, 2019		42,958,401
Ending balance at Sep. 30, 2019	$ 245,957	$ 4	$ 630,966	$ 1,172	$ (386,185)

MARKETABLE SECURITIES - Marketable Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale [Line Items]
Marketable securities	$ 341,835	$ 368,668
Commercial paper
Debt Securities, Available-for-sale [Line Items]
Marketable securities	43,504	59,255
Corporate debt securities
Debt Securities, Available-for-sale [Line Items]
Marketable securities	287,188	299,413
Securities of government sponsored entities
Debt Securities, Available-for-sale [Line Items]
Marketable securities	$ 11,143	$ 10,000

LOSS PER COMMON SHARE (Tables)

9 Months Ended

Sep. 30, 2019

Earnings Per Share [Abstract]

Schedule of basic and diluted net income (loss) per share

Basic and diluted net loss per share is calculated as follows (net loss amounts are stated in thousands):



	Three Months Ended September 30,
	2019							2018
	Shares	Net Loss			EPS			Shares	Net Loss			EPS
Basic and diluted loss per share	42,943,828	$	(36,490	)	$	(0.85	)	40,717,440	$	(54,516	)	$	(1.34	)



	Nine Months Ended September 30,
	2019							2018
	Shares	Net Loss			EPS			Shares	Net Loss			EPS
Basic and diluted loss per share	42,109,618	$	(116,168	)	$	(2.76	)	40,149,184	$	(95,223	)	$	(2.37	)

Schedule of common stock options, convertible debt and restricted stock units anti-dilutive

The following common stock equivalents have been excluded because they were anti-dilutive (in thousands):



	Three Months Ended September 30,		Nine Months Ended September 30,
	2019	2018	2019	2018
Restricted stock units	809	477	704	335
Convertible debt	7,113	8,411	7,805	8,411
Options	7,527	7,390	7,709	7,202
Warrants	—	40	—	377
Total anti-dilutive shares	15,449	16,318	16,218	16,325

FUTURE ACQUISITION RIGHT AND JOINT DEVELOPMENT AGREEMENT (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended
	Jan. 31, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Jun. 30, 2019	Dec. 31, 2018	Jun. 30, 2016
Variable Interest Entity [Line Items]
Business combination-related contingent consideration		$ 73,900		$ 73,900			$ 93,000	$ 25,000
Investment						$ 15,000
Business combination, option agreement, purchase price	$ 65,000
Business combination, option agreement, purchase price, percent transferred In cash	20.00%
Business combination, option agreement, purchase price, percent transferred by issuance of equity	80.00%
Business combination, option agreement, share price (in dollars per share)	$ 21.40
Business combination, option agreement, percent of consideration paid in cash if share price falls below share price threshold	100.00%
Business combination, option agreement, contingent consideration	$ 25,000
Impairment of long-term investment		$ 15,000	$ 0	$ 15,000	$ 0
Censa Pharmaceuticals Inc.
Variable Interest Entity [Line Items]
Payments for the option to acquire business	10,000
Business combination-related contingent consideration	19,900
Business combination, development funding	$ 2,800
Business combination, option agreement, weighted average ten day share price, which requires all cash payment (in dollars per share)	$ 19.26
Censa Pharmaceuticals, Inc, Equity Holders
Variable Interest Entity [Line Items]
Additional required payments for the option to acquire business, successful development milestones	$ 5,000

SHARE BASED COMPENSATION - Exercise of Warrants (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2018	Sep. 30, 2019	Dec. 31, 2018
Equity [Abstract]
Warrants exercised (in shares)	532,830	956,887
Proceeds from warrant exercises	$ 2.1	$ 4.3
Warrants outstanding (in shares)			0	0

DESCRIPTION OF BUSINESS (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended			9 Months Ended		12 Months Ended
DESCRIPTION OF BUSINESS (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Sep. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Impairment of L-UDCA IPR&D intangible asset		$ 0	$ 25,500	$ 0	$ 25,500	$ 0
Write off of L-UDCA contingent consideration		0	18,000	$ 0	18,000	0
Loss on write-off of L-UDCA			7,500
Payments to acquire L-UDCA	$ 500
IPR&D asset		241,195			241,195		$ 255,643
Business combination-related contingent consideration	25,000	$ 73,900			73,900		93,000
Adjustments to contingent consideration					$ (4,329)	$ (6,852)	1,000	$ (5,700)	$ (2,300)
Acquired Product Rights L-UDCA
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Impairment of L-UDCA IPR&D intangible asset			25,500
Write off of L-UDCA contingent consideration			$ 18,000
IPR&D asset	$ 25,500						25,500
Business combination-related contingent consideration							$ 18,000

INTANGIBLE ASSETS - Amortizable Intangible Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Finite-lived intangible assets	$ 241,195	$ 255,643
Less: accumulated amortization	(83,396)	(68,952)
Net carrying value	$ 157,799	$ 186,691

SHARE BASED COMPENSATION - Performance Based Restricted Stock Activity (Details) - Performance Shares $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2019 USD ($) $ / shares shares
Number of Shares
Beginning balance (in shares) \| shares	226,750
Granted (in shares) \| shares	80,000
Vested (in shares) \| shares	0
Forfeited/canceled (in shares) \| shares	(73,250)
Ending balance (in share) \| shares	233,500
Weighted Average Grant Date Fair Value
Beginning balance (in dollars per share) \| $ / shares	$ 21.54
Granted (in dollars per share) \| $ / shares	21.32
Vested (in dollars per share) \| $ / shares	0
Forfeited/canceled (in dollars per share) \| $ / shares	23.33
Ending balance (in dollars per share) \| $ / shares	$ 20.90
Unamortized stock compensation expense \| $	$ 0.7
Weighted-average recognition period (in years)	1 year

MARKETABLE SECURITIES

9 Months Ended

Sep. 30, 2019

Investments, Debt and Equity Securities [Abstract]

MARKETABLE SECURITIES

The Company's marketable securities as of September 30, 2019 and December 31, 2018 were comprised of available-for-sale marketable securities which are carried at fair value, with the unrealized gains and losses reported in accumulated other comprehensive income (loss). Realized gains and losses and declines in value judged to be other-than-temporary, if any, on available-for-sale securities are included in other income or expense. Interest and dividends on securities classified as available-for-sale are included in interest income. The amortized cost of debt securities is adjusted for amortization of premiums and accretion of discounts to maturity. Such amortization and accretion is included in interest income. During the nine months ended September 30, 2019, investment activity for the Company included $180.8 million in maturities and $151.0 million in purchases, all relating to debt based marketable securities.

Marketable securities consisted of the following (in thousands):



	September 30, 2019		December 31, 2018
Commercial paper	$	43,504	$	59,255
Corporate debt securities	287,188		299,413
Securities of government sponsored entities	11,143		10,000
Total marketable securities:	$	341,835	$	368,668

The following is a summary of short-term marketable securities classified as available-for-sale as of September 30, 2019 (in thousands):



	Remaining Contractual Maturity (in years)	Amortized Cost		Unrealized Gains		Unrealized Losses			Aggregate Estimated Fair Value
Commercial paper	Less than 1	$	43,479	$	28	$	(3	)	$	43,504
Corporate debt securities	Less than 1	186,885		537		(15		)	187,407
Total maturity less than 1 year		230,364		565		(18		)	230,911
Corporate debt securities	1 to 2	99,216		598		(33		)	99,781
Securities of government-sponsored entities	1 to 2	11,177		—		(34		)	11,143
Total maturity 1 to 2 years		110,393		598		(67		)	110,924
Total available-for-sale securities		$	340,757	$	1,163	$	(85	)	$	341,835

The following is a summary of short-term marketable securities classified as available-for-sale as of December 31, 2018 (in thousands):



	Remaining Contractual Maturity (in years)	Amortized Cost		Unrealized Gains		Unrealized Losses			Aggregate Estimated Fair Value
Commercial paper	Less than 1	$	59,313	$	—	$	(58	)	$	59,255
Corporate debt securities	Less than 1	149,824		—		(604		)	149,220
Total maturity less than 1 year		209,137		—		(662		)	208,475
Corporate debt securities	1 to 2	150,813		18		(638		)	150,193
Securities of government-sponsored entities	1 to 2	9,997		4		(1		)	10,000
Total maturity 1 to 2 years		160,810		22		(639		)	160,193
Total available-for-sale securities		$	369,947	$	22	$	(1,301	)	$	368,668

The primary objective of the Company’s investment portfolio is to enhance overall returns while preserving capital and liquidity. The Company’s investment policy limits interest-bearing security investments to certain types of instruments issued by institutions with primarily investment grade credit ratings and places restrictions on maturities and concentration by asset class and issuer. All available-for-sale securities are held in current assets regardless of contractual maturities exceeding one year, as the Company has the ability to sell them within the next twelve months.

The Company reviews the available-for-sale investments for other-than-temporary declines in fair value below cost basis each quarter and whenever events or changes in circumstances indicate that the cost basis of an asset may not be recoverable. This evaluation is based on a number of factors, including the length of time and the extent to which the fair value has been below the cost basis and adverse conditions related specifically to the security, including any changes to the credit rating of the security, and the intent to sell, or whether the Company will more likely than not be required to sell the security before recovery of its amortized cost basis. The assessment of whether a security is other-than-temporarily impaired could change in the future due to new developments or changes in assumptions related to any particular security. As of September 30, 2019 and December 31, 2018, the Company believed the cost basis for available-for-sale investments was recoverable in all material respects.

BASIS OF PRESENTATION AND SIGNIFICANT ACCCOUNTING POLICIES (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Accounting Policies [Abstract]
Impairment of long-term investment	$ 15,000	$ 0	$ 15,000	$ 0
Marketable securities	$ 341,835		$ 341,835		$ 368,668

DISPOSITIONS (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended			9 Months Ended		12 Months Ended
DISPOSITIONS (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Sep. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Payments to acquire L-UDCA	$ 500
IPR&D asset		$ 241,195			$ 241,195		$ 255,643
Business combination-related contingent consideration	25,000	73,900			73,900		93,000
Adjustments to contingent consideration					(4,329)	$ (6,852)	1,000	$ (5,700)	$ (2,300)
Impairment of L-UDCA IPR&D intangible asset		0	$ 25,500	$ 0	25,500	0
Write off of L-UDCA contingent consideration		0	18,000	0	18,000	0
Loss on write-off of L-UDCA			7,500
Impairment of long-term investment		$ 15,000		$ 0	$ 15,000	$ 0
Acquired Product Rights L-UDCA
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
IPR&D asset	$ 25,500						25,500
Business combination-related contingent consideration							$ 18,000
Impairment of L-UDCA IPR&D intangible asset			25,500
Write off of L-UDCA contingent consideration			$ 18,000

SHARE BASED COMPENSATION - Stock based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 4,340	$ 4,885	$ 16,608	$ 14,920
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	1,735	1,603	5,301	4,592
Selling, general & administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense	$ 2,605	$ 3,282	$ 11,307	$ 10,328

CONVERTIBLE NOTES PAYABLE CONVERTIBLE NOTES PAYABLE (Tables)

9 Months Ended

Sep. 30, 2019

Debt Disclosure [Abstract]

Schedule of long-term debt instruments



	Three Months Ended September 30,				Nine Months Ended September 30,
	2019		2018		2019		2018
Contractual interest expense	$	1,725	$	383	$	5,175	$	383
Amortization of debt discount	2,239		468		6,591		468
Amortization of debt issuance costs	224		50		672		50
Total interest expense for the 2025 Notes	$	4,188	$	901	$	12,438	$	901

The composition of the Company’s 2025 Notes are as follows (in thousands):



	September 30, 2019			December 31, 2018
2.50% convertible senior notes due 2025	$	276,000		$	276,000
Unamortized debt discount	(68,245		)	(74,836		)
Unamortized debt issuance costs	(5,400		)	(6,073		)
Total 2025 Notes, net of unamortized debt discount and debt issuance costs	$	202,355		$	195,091

The composition of the Company’s 2019 Notes at December 31, 2018 was as follows (in thousands):



	December 31, 2018
4.50% senior convertible notes due 2019	$	22,590
Unamortized debt discount	(125		)
Unamortized debt issuance costs	(8		)
Total 2019 Notes, net of unamortized debt discount and debt issuance costs	$	22,457

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28541-108399

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21506-112644

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(e),(f))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399

Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21521-112644

Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21538-112644

Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

Reference 9: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21475-112644

+ Details

LEASES

9 Months Ended

Sep. 30, 2019

Leases [Abstract]

LEASES

As of January 1, 2019, the Company adopted ASU No. 2016-02, Leases, using a modified retrospective basis method under which prior comparative periods are not restated.

The new standard establishes an ROU model that requires a lessee to record an ROU asset and a lease liability on its balance sheet for all leases with terms longer than 12 months. Leases will be classified as either finance or operating, with classification affecting the pattern of expense recognition in the income statement. In addition, the FASB issued ASU No. 2018-10, Codification Improvements to Topic 842, ASU No. 2018-11, Targeted Improvements, and ASU No. 2018-20, Narrow-Scope Improvements for Lessors, to clarify and amend the guidance in ASU No. 2016-02. The Company has elected the following as practical expedients from within these ASUs: 1) an entity need not reassess whether any expired or existing contracts are or contain leases; 2) an entity need not reassess the lease classification for any expired or existing leases; and 3) an entity need not reassess initial direct costs for any existing leases.

As of January 1, 2019, the Company had a single operating lease for its office located in San Diego, California. The lease was originally signed in July 2016, was amended in July 2017, and is for approximately 45,000 square feet of office space in adjacent buildings. The term of the original lease is 7 years, 7 months, and is coterminous for all space occurring in July 2024. Under the terms of the lease, the Company will pay base annual rent (subject to an annual fixed percentage increase), plus property taxes and other normal and necessary expenses, such as utilities, repairs, security and maintenance. Certain incentives were included in the lease, including approximately $2.3 million in tenant improvement allowances and seven months of rent abatement. The Company has the right to extend the lease for five years.

As of January 1, 2019, the Company's remaining minimum lease payments and unamortized lease incentives were approximately $14.0 million and $1.8 million, respectively. Using a discount rate equal to our borrowing rate of 7.7% and a remaining term of 5 years, 7 months, the Company determined the ROU asset and lease liability as of adoption were $7.9 million and $11.3 million, respectively. There was no cumulative adjustment to our beginning accumulated deficit balance.

In March 2019, the Company amended the existing office lease to add approximately 16,000 square feet of office space in adjacent buildings; 12,000 square feet has been occupied as of September 30, 2019. The total additional space is expected to be utilized through August 2020 and has future minimum lease payments of approximately $1.0 million. The Company determined the ROU asset and lease liability were each $0.4 million for the lease space that has commenced and is occupied as of September 30, 2019.

On April 23, 2019, the Company entered into an office lease with an effective date of April 12, 2019 with Kilroy Realty, L.P. (the "Landlord") for the lease of approximately 77,000 square feet of the building located at 3611 Valley Centre Drive, San Diego, California. The Company expects to use the premises as its new principal corporate offices and plans to consolidate its corporate headquarters into the premises from the current location of multiple suites in adjacent buildings at 3721 and 3661 Valley Centre Drive, San Diego, California. Under the terms of the lease, the Company will have the one-time right of first offer on the suites it currently occupies and a general right of first offer to lease additional space from the Landlord in the development. The commencement date of the lease is expected to be October 1, 2020. The initial term of the lease is 7 years, 7 months, and the Landlord has granted the Company an option to extend the term of the lease by a period of 5 years. The aggregate base rent due over the initial term of the lease is approximately $36.5 million.

Following is a schedule of the future minimum rental commitments for our operating lease reconciled to the lease liability and ROU assets as of September 30, 2019 (in thousands):



	September 30, 2019
2019	$	787
2020	2,958
2021	2,486
2022	2,560
2023	2,637
Thereafter	1,585
Total undiscounted future minimum payments	13,013
Present value discount	(2,538		)
Total lease liability	10,475
Lease incentives	(1,543		)
Straight line lease expense in excess of cash payments	(1,585		)
Total ROU asset	$	7,347

As of September 30, 2019, the current and non-current portions of the ROU asset were recorded to the Condensed Consolidated Balance Sheets as follows (in thousands):



	September 30, 2019
Prepaid expenses and other current assets	$	2,147
Other non-current assets	5,200
Total ROU asset	$	7,347

As of September 30, 2019, the current and non-current portions of the lease liability were recorded to the Condensed Consolidated Balance Sheets as follows (in thousands):



	September 30, 2019
Other current liabilities	$	2,668
Other non-current liabilities	7,807
Total lease liabilities	$	10,475

For the three and nine months ended September 30, 2019, the Company recorded $0.7 million and $2.0 million in expense related to operating leases, respectively.

LEASES - Additional Information (Details) ft² in Thousands, $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2019 USD ($) ft²	Sep. 30, 2019 USD ($) ft²	Apr. 23, 2019 USD ($) ft²	Jan. 01, 2019 USD ($)	Jul. 31, 2016 USD ($) ft²
Lessee, Lease, Description [Line Items]
Square footage leased \| ft²					45
Operating lease term					7 years 7 months
Lease incentives	$ 1,543	$ 1,543		$ 1,800	$ 2,300
Operating lease extension term				5 years
Future minimum lease payments	13,013	13,013		$ 14,000
Operating lease discount rate				7.70%
Remaining lease term				5 years 7 months
Operating lease right-of-use asset	7,347	7,347		$ 7,900
Total lease liability	10,475	10,475		$ 11,300
Operating lease expense	$ 700	$ 2,000
3611 Valley Centre Drive, San Diego, California
Lessee, Lease, Description [Line Items]
Square footage leased \| ft²			77
Operating lease extension term			5 years
Future minimum lease payments			$ 36,500
Remaining lease term			7 years 7 months
March 2019 Operating Lease Amendment
Lessee, Lease, Description [Line Items]
Square footage leased \| ft²	16	16
Square footage leased and occupied \| ft²	12	12
Future minimum lease payments	$ 1,000	$ 1,000
Operating lease right-of-use asset	400	400
Total lease liability	$ 400	$ 400