Cidara Therapeutics (CDTX) 10-Q 13 Aug 20 2020 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2020	Jul. 31, 2020
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q2
Entity Registrant Name	Cidara Therapeutics, Inc.
Trading Symbol	CDTX
Entity Central Index Key	0001610618
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Entity Interactive Data Current	Yes
Entity Emerging Growth Company	true
Entity Small Business	true
Entity Ex Transition Period	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding (in shares)		42,959,195

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 54,826	$ 50,268
Restricted cash	9,259	10,000
Accounts receivable, prepaid expenses and other current assets	5,954	5,546
Total current assets	70,039	65,814
Property and equipment, net	472	429
Operating lease right-of-use asset	1,257	1,632
Other assets	1,635	1,101
Total assets	73,403	68,976
Current liabilities:
Accounts payable	2,933	1,887
Accrued liabilities	4,426	4,068
Accrued compensation and benefits	2,900	3,658
Deferred revenue	11,196	9,803
Current portion of lease liability	878	818
Current portion of term loan	9,234	9,965
Total current liabilities	31,567	30,199
Lease liability	484	942
Total liabilities	32,051	31,141
Commitments and contingencies
Stockholders' equity:
Preferred stock
Common stock, $0.0001 par value; 200,000,000 shares authorized at June 30, 2020 and December 31, 2019; 42,019,195 and 33,838,466 shares issued and outstanding at June 30, 2020 and December 31, 2019, respectively	4	3
Additional paid-in capital	336,782	297,659
Accumulated deficit	(295,434)	(259,827)
Total stockholders' equity	41,352	37,835
Total liabilities and stockholders' equity	73,403	68,976
Series X Convertible Preferred Stock
Stockholders' equity:
Preferred stock	0	0
Total stockholders' equity	$ 0	$ 0

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Jun. 30, 2020	Dec. 31, 2019
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	200,000,000	200,000,000
Common stock, shares issued (in shares)	42,019,195	33,838,466
Common stock, shares outstanding (in shares)	42,019,195	33,838,466
Series X Convertible Preferred Stock
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized (in shares)	5,000,000	5,000,000
Preferred stock, shares issued (in shares)	1,096,519	565,231
Preferred stock, shares outstanding (in shares)	1,096,519	565,231

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Income Statement [Abstract]
Revenue	$ 3,392	$ 0	$ 5,922	$ 0
Operating expenses:
Research and development	17,634	10,743	30,630	23,412
General and administrative	3,969	3,525	8,064	7,260
Total operating expenses	21,603	14,268	38,694	30,672
Loss from operations	(18,211)	(14,268)	(32,772)	(30,672)
Other income (expense):
Change in fair value of contingent forward purchase obligations	0	681	0	411
Interest (expense) income, net	(95)	40	(73)	153
Total other (expense) income, net	(95)	721	(73)	564
Net loss and comprehensive loss	(18,306)	(13,547)	(32,845)	(30,108)
Recognition of beneficial conversion feature	0	0	2,762	0
Net loss attributable to common shareholders	$ (18,306)	$ (13,547)	$ (35,607)	$ (30,108)
Basic earnings (loss) per common share (in dollars per share)	$ (0.45)	$ (0.47)	$ (0.90)	$ (1.19)
Shares used to compute basic net income (loss) per share (in shares)	40,965,180	28,590,651	39,410,751	25,248,314

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Operating activities:
Net loss	$ (32,845)	$ (30,108)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	143	170
Stock-based compensation	2,241	2,541
Non-cash interest expense	8	15
Amortization of debt issuance costs	2	4
Operating lease right-of-use assets and liabilities, net	(23)	60
Change in fair value of contingent forward purchase obligations	0	(411)
Changes in assets and liabilities:
Accounts receivable, prepaid expenses, other current assets, and other assets	(974)	(781)
Accounts payable and accrued liabilities	1,381	(1,357)
Accrued compensation and benefits	(526)	(87)
Deferred revenue	1,393	0
Net cash used in operating activities	(29,200)	(29,954)
Investing activities:
Purchases of property and equipment	(132)	(35)
Net cash used in investing activities	(132)	(35)
Financing activities:
Proceeds from issuance of common and preferred stock pursuant to rights offering, net of issuance costs	29,186	0
Proceeds from issuance of common stock, net of issuance costs	4,699	0
Proceeds from exercise of stock options	5	0
Principal paid on Term Loan	(741)	0
Net cash provided by financing activities	33,149	0
Net increase (decrease) in cash, cash equivalents, and restricted cash	3,817	(29,989)
Cash, cash equivalents, and restricted cash at beginning of period	60,268	74,562
Cash, cash equivalents, and restricted cash at end of period	64,085	44,573
Supplemental disclosure of cash flows:
Interest paid	255	315
Non-cash investing activities:
Property and equipment included in accounts payable	55	0
Right-of-use asset obtained in exchange for lease liability	0	2,295
Non-cash financing activities:
Sale of shares pursuant to Employee Stock Purchase Plan	$ 231	$ 210

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Changes in Convertible Preferred Stock and Stockholders' Equity - USD ($) $ in Thousands	Total	Series X Convertible Preferred Stock	Common Stock	Additional Paid-In Capital	Accumulated Deficit	Rights Offering, February 2020	Rights Offering, February 2020Series X Convertible Preferred Stock	Rights Offering, February 2020Common Stock	Rights Offering, February 2020Additional Paid-In Capital
Balance, beginning (in shares) at Dec. 31, 2018		445,231	27,816,014
Balance, beginning at Dec. 31, 2018	$ 59,139	$ 0	$ 3	$ 277,871	$ (218,735)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	1,284			1,284
Net income (loss)	(16,561)				(16,561)
Vesting of restricted stock units (in shares)			25,837
Vesting of restricted stock units	0			0
Issuance of Series X Convertible Preferred Stock in exchange for common stock (in shares)		120,000	(1,200,000)
Issuance of Series X Convertible Preferred Stock in exchange for common stock	0
Balance, ending (in shares) at Mar. 31, 2019		565,231	26,641,851
Balance, ending at Mar. 31, 2019	43,862	$ 0	$ 3	279,155	(235,296)
Balance, beginning (in shares) at Dec. 31, 2018		445,231	27,816,014
Balance, beginning at Dec. 31, 2018	59,139	$ 0	$ 3	277,871	(218,735)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(30,108)
Balance, ending (in shares) at Jun. 30, 2019		565,231	26,767,989
Balance, ending at Jun. 30, 2019	31,782	$ 0	$ 3	280,622	(248,843)
Balance, beginning (in shares) at Mar. 31, 2019		565,231	26,641,851
Balance, beginning at Mar. 31, 2019	43,862	$ 0	$ 3	279,155	(235,296)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	1,257			1,257
Net income (loss)	(13,547)				(13,547)
Issuance of common stock under Employee Stock Purchase Plan (in shares)			126,138
Issuance of common stock under Employee Stock Purchase Plan	210			210
Balance, ending (in shares) at Jun. 30, 2019		565,231	26,767,989
Balance, ending at Jun. 30, 2019	31,782	$ 0	$ 3	280,622	(248,843)
Balance, beginning (in shares) at Dec. 31, 2019		565,231	33,838,466
Balance, beginning at Dec. 31, 2019	37,835	$ 0	$ 3	297,659	(259,827)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock, net of offering costs (in shares)			7,600				531,288	6,639,307
Issuance of common stock, net of offering costs	19			19		$ 29,186		$ 1	$ 29,185
Recognition of beneficial conversion feature	0			2,762	(2,762)
Issuance of common stock for exercise of stock options (in shares)			1,834
Issuance of common stock for exercise of options	5			5
Issuance of common stock for restricted share units vested (in shares)			72,304
Issuance of common stock for restricted share units vested	0			0
Stock-based compensation	1,246			1,246
Net income (loss)	(14,539)				(14,539)
Balance, ending (in shares) at Mar. 31, 2020		1,096,519	40,559,511
Balance, ending at Mar. 31, 2020	53,752	$ 0	$ 4	330,876	(277,128)
Balance, beginning (in shares) at Dec. 31, 2019		565,231	33,838,466
Balance, beginning at Dec. 31, 2019	$ 37,835	$ 0	$ 3	297,659	(259,827)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Recognition of beneficial conversion feature				2,800
Issuance of common stock for exercise of stock options (in shares)	1,834
Net income (loss)	$ (32,845)
Balance, ending (in shares) at Jun. 30, 2020		1,096,519	42,019,195
Balance, ending at Jun. 30, 2020	41,352	$ 0	$ 4	336,782	(295,434)
Balance, beginning (in shares) at Mar. 31, 2020		1,096,519	40,559,511
Balance, beginning at Mar. 31, 2020	53,752	$ 0	$ 4	330,876	(277,128)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock, net of offering costs (in shares)			1,326,769
Issuance of common stock, net of offering costs	4,680			4,680
Stock-based compensation	995			995
Net income (loss)	(18,306)				(18,306)
Issuance of common stock under Employee Stock Purchase Plan (in shares)			132,915
Issuance of common stock under Employee Stock Purchase Plan	231			231
Balance, ending (in shares) at Jun. 30, 2020		1,096,519	42,019,195
Balance, ending at Jun. 30, 2020	$ 41,352	$ 0	$ 4	$ 336,782	$ (295,434)

THE COMPANY AND BASIS OF PRESEN

THE COMPANY AND BASIS OF PRESENTATION	6 Months Ended
	Jun. 30, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
THE COMPANY AND BASIS OF PRESENTATION	THE COMPANY AND BASIS OF PRESENTATION Description of Business Cidara Therapeutics, Inc., or the Company, was originally incorporated in Delaware in December 2012 as K2 Therapeutics, Inc., and its name was changed to Cidara Therapeutics, Inc. in July 2014. The Company is a biotechnology company focused on the discovery, development and commercialization of novel anti-infectives for the treatment and prevention of diseases that are inadequately addressed by current standard of care therapies. The Company is developing a pipeline of product and development candidates, with a focus on serious fungal and viral infections. The Company’s lead product candidate is rezafungin acetate, an intravenous formulation of a novel echinocandin being developed for the treatment and prevention of serious fungal infections. The Company is also advancing its Cloudbreak® antiviral platform to develop Antiviral Fc-Conjugates, or AVCs, for the prevention and treatment of influenza and other viral infections. The Company formed wholly-owned subsidiaries, Cidara Therapeutics UK Limited, in England, and Cidara Therapeutics (Ireland) Limited, in Ireland, in March 2016 and October 2018, respectively, for the purpose of developing its product candidates in Europe. Basis of Presentation The Company has a limited operating history and the sales and income potential of the Company’s business and market are unproven. The Company has experienced net losses and negative cash flows from operating activities since its inception. At June 30, 2020 , the Company had an accumulated deficit of $295.4 million . The Company expects to continue to incur net losses into the foreseeable future. Successful transition to attaining profitable operations is dependent upon achieving a level of revenues adequate to support the Company’s cost structure. At June 30, 2020 , the Company had cash, cash equivalents and restricted cash of $64.1 million . Based on the Company’s current business plan, management believes that existing cash and cash equivalents will not be sufficient to fund the Company’s obligations for twelve months from the issuance of these financial statements. The Company’s ability to execute its operating plan depends on its ability to obtain additional funding through equity offerings, debt financings or potential licensing and collaboration arrangements. The accompanying consolidated financial statements have been prepared assuming the Company will continue as a going concern, which contemplates the realization of assets and settlement of liabilities in the normal course of business. However, the Company’s current working capital, anticipated operating expenses and net losses and the uncertainties surrounding its ability to raise additional capital as needed, as discussed below, raise substantial doubt about its ability to continue as a going concern for a period of one year following the date that these financial statements are issued. The consolidated financial statements do not include any adjustments for the recovery and classification of assets or the amounts and classification of liabilities that might be necessary should the Company be unable to continue as a going concern. The Company plans to continue to fund its losses from operations through cash and cash equivalents on hand, as well as through future equity offerings, debt financings, other third party funding, and potential licensing or collaboration arrangements. There can be no assurance that additional funds will be available when needed from any source or, if available, will be available on terms that are acceptable to the Company. Even if the Company raises additional capital, it may also be required to modify, delay or abandon some of its plans which could have a material adverse effect on the Company’s business, operating results and financial condition and the Company’s ability to achieve its intended business objectives. Any of these actions could materially harm the Company’s business, results of operations and future prospects. In addition to the foregoing, the Company is monitoring closely the impact of the COVID-19 pandemic on its business and has taken steps designed to protect the health and safety of its employees while continuing its operations. Given the level of uncertainty regarding the duration and impact of the COVID-19 pandemic on capital markets and the U.S. economy, the Company is currently unable to assess the impact of the COVID-19 pandemic on its future access to capital. The Company is continuing to monitor the spread of COVID-19 and its potential impact on the Company's operations. The full extent to which the COVID-19 pandemic will impact the Company's business, results of operations, financial condition, clinical trials, and preclinical research will depend on future developments that are highly uncertain, including actions taken to contain or treat COVID-19 and their effectiveness, as well as the economic impact on national and international markets. Unaudited Interim Financial Data The accompanying condensed consolidated financial statements are unaudited and have been prepared by the Company in accordance with U.S. generally accepted accounting principles, or GAAP, as found in the Accounting Standards Codification, or ASC, of the Financial Accounting Standards Board, or FASB. Certain information and footnote disclosures normally included in the Company’s annual financial statements have been condensed or omitted. These interim condensed consolidated financial statements, in the opinion of management, reflect all normal recurring adjustments necessary for a fair presentation of the Company’s financial position and results of operations for the interim periods ended June 30, 2020 and 2019 . Basis of Consolidation The consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All significant intercompany accounts and transactions have been eliminated in consolidation. Segment Information Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision maker, the Chief Executive Officer, in making decisions regarding resource allocation and assessing performance. The Company views its operations and manages its business as one operating segment.

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	6 Months Ended
	Jun. 30, 2020
Accounting Policies [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Cash and Cash Equivalents The Company considers all short-term investments purchased with a maturity of three months or less when acquired to be cash equivalents. Restricted cash represents cash that the Company is required to maintain on hand in order to maintain compliance with an operating covenant in the Third Amendment to the Company's Loan Agreement with Pacific Western Bank. See Note 4 for more information. Concentration of Credit Risk The Company’s financial instruments that are exposed to concentrations of credit risk consist primarily of cash and cash equivalents. The Company maintains deposits in government insured financial institutions in excess of government insured limits. The Company invests its cash balances in financial institutions that it believes have high credit quality, has not experienced any losses on such accounts and does not believe it is exposed to significant credit risk. Patent Costs The Company expenses all costs as incurred in connection with patent applications (including direct application fees, and the legal and consulting expenses related to making such applications), and such costs are included in general and administrative expenses in the accompanying statements of operations. Income Taxes The Company follows the FASB's ASC 740, Income Taxes, in reporting deferred income taxes. ASC 740 requires a company to recognize deferred tax assets and liabilities for expected future income tax consequences of events that have been recognized in the Company’s consolidated financial statements. Under this method, deferred tax assets and liabilities are determined based on temporary differences between financial statement carrying amounts and the tax basis of assets and liabilities using enacted tax rates in the years in which the temporary differences are expected to reverse. Valuation allowances are provided if, based on the weight of available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. The Company accounts for uncertain tax positions pursuant to ASC 740, which prescribes a recognition threshold and measurement process for financial statement recognition of uncertain tax positions taken or expected to be taken in a tax return. If the tax position meets this threshold, the benefit to be recognized is measured as the tax benefit having the highest likelihood of being realized upon ultimate settlement with the taxing authority. The Company recognizes interest accrued related to unrecognized tax benefits and penalties in the provision for income taxes. Revenue Recognition The Company recognizes revenue is accordance with Accounting Standards Codification, or ASC, Topic 606, Revenue from Contracts with Customers, which applies to all contracts with customers, except for contracts that are within the scope of other standards, such as leases, insurance, collaboration arrangements and financial instruments. Under Topic 606, an entity recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration that 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 the consideration it is entitled to in exchange for the goods or services it transfers to the customer. At contract inception, once the contract is determined to be within the scope of Topic 606, the Company assesses the goods or services promised within each contract and determines those that are performance obligations, and assesses whether each promised good or service is distinct. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) the performance obligation is satisfied. In a contract with multiple performance obligations, the Company must develop estimates and assumptions that require judgment to determine the underlying stand-alone selling price for each performance obligation, which determines how the transaction price is allocated among the performance obligations. The estimation of the stand-alone selling price(s) may include estimates regarding forecasted revenues or costs, development timelines, discount rates, and probabilities of technical and regulatory success. The Company evaluates each performance obligation to determine if it can be satisfied at a point in time or over time. Any change made to estimated progress towards completion of a performance obligation and, therefore, revenue recognized will be recorded as a change in estimate. In addition, variable consideration must be evaluated to determine if it is constrained and, therefore, excluded from the transaction price. If a license to the Company’s intellectual property is determined to be distinct from the other performance obligations identified in a contract, the Company recognizes revenues from the transaction price allocated to the license when the license is transferred to the licensee and the licensee is able to use and benefit from the license. For licenses that are bundled with other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue from the allocated transaction price. The Company evaluates the measure of progress at each reporting period and, if necessary, adjusts the measure of performance and related revenue or expense recognition as a change in estimate. At the inception of each arrangement that includes milestone payments, the Company evaluates whether the milestones are considered probable of being reached. If it is probable that a significant revenue reversal would not occur, the associated milestone value is included in the transaction price. Milestone payments that are not within the Company’s or a collaboration partner’s control, such as regulatory approvals, are generally not considered probable of being achieved until those approvals are received. At the end of each reporting period, the Company re-evaluates the probability of achievement of milestones that are within its or a collaboration partner’s control, such as operational developmental milestones and any related constraint, and, if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which will affect collaboration revenues and earnings in the period of adjustment. Revisions to the Company’s estimate of the transaction price may also result in negative collaboration revenues and earnings in the period of adjustment. For arrangements that include sales-based royalties, including commercial milestone payments based on the level of sales, and a license is deemed to be the predominant item to which the royalties relate, the Company will recognize revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied, or partially satisfied. To date, the Company has not recognized any royalty revenue from collaborative arrangements. In September 2019, the Company entered into a Collaboration and License Agreement, or the Collaboration Agreement, with Mundipharma Medical Company, or Mundipharma. The Company concluded that there were three significant performance obligations under the Collaboration Agreement: the license, the research and development services, and the clinical supply services, and that the obligations are distinct from each other. Revenue associated with the license was recognized upon delivery in September 2019. The Company concluded that progress towards completion of the research and development and clinical supply performance obligations related to the Collaboration Agreement is best measured in an amount proportional to the collaboration expenses incurred and the total estimated collaboration expenses. The Company periodically reviews and updates the estimated collaboration expenses, when appropriate, which may adjust revenue recognized for the period. While such changes to the Company’s estimates have no impact on the Company’s reported cash flows, the amount of revenue recorded in the period could be materially impacted. The transaction price to be recognized as revenue under the Collaboration Agreement consists of the upfront payment and estimated reimbursable research and development and clinical supply costs. Potential future payments for variable consideration, such as clinical, regulatory or commercial milestones, will be recognized when it is probable that, if recorded, a significant reversal will not take place. Potential future royalty payments will be recorded as revenue when the associated sales occur. See Note 7 - Significant Agreements and Contracts for more information. Grant Funding The Company has evaluated the terms of the research and development grants to assess its obligations and the classification of funding received. Amounts billable for funded research and development are recognized in the statement of operations as a reduction to research and development expense over the grant period as the related costs are incurred to meet the Company's obligations. Research and Development Costs Research and development expenses consist of wages, benefits and stock-based compensation charges for research and development employees, scientific consultant fees, facilities and overhead expenses, laboratory supplies, manufacturing expenses, and nonclinical and clinical trial costs. The Company accrues nonclinical and clinical trial expenses based on work performed, which relies on estimates of total costs incurred based on patient enrollment, completion of studies, and other events. Preclinical and Clinical Trial Accruals The Company makes estimates of its accrued expenses as of each balance sheet date in the financial statements based on the facts and circumstances known at that time. Accrued expenses for preclinical studies and clinical trials are based on estimates of costs incurred and fees that may be associated with services provided by contract research organizations, or CROs, clinical trial investigational sites and other clinical trial-related activities. Payments under certain contracts with such parties depend on factors such as successful enrollment of patients, site initiation and the completion of clinical trial milestones. In accruing for these services, the Company estimates the time period over which services will be performed and the level of effort to be expended in each period. If possible, the Company obtains information regarding unbilled services directly from these service providers. However, the Company may be required to estimate these services based on other available information. If the Company underestimates or overestimates the activities or fees associated with a study or service at a given point in time, adjustments to research and development expenses may be necessary in future periods. Historically, estimated accrued liabilities have approximated actual expense incurred. Subsequent changes in estimates may result in a material change in accruals. Stock-based Compensation The Company accounts for stock-based compensation expense related to stock options and employee stock purchase plan rights by estimating the fair value on the date of grant using the Black-Scholes option pricing model. The fair value of Restricted Stock Units, or RSUs, and Performance-based RSUs, or PRSUs, is estimated based on the closing price of the Company's common stock on the date of grant. For awards subject to time-based vesting conditions, stock-based compensation expense is recognized ratably over the requisite service period of the awards. For awards subject to performance-based vesting conditions, the Company assesses the probability of achievement of the individual milestones under the stock-based awards and recognizes stock-based compensation expense over the implicit service period commencing once the Company believes the performance criteria is probable of achievement. The Company recognizes forfeitures related to stock-based compensation as they occur. Net Loss Per Share Basic net loss per share is calculated by dividing the net loss allocable to common shares by the weighted-average number of common shares outstanding for the period, without consideration for potentially dilutive securities. Diluted net loss per share is computed by dividing the net loss allocable to common shares by the weighted-average number of common shares and dilutive common stock equivalents outstanding for the period determined using the treasury-stock and if-converted methods. Dilutive common stock equivalents are comprised of warrants, Series X Convertible Preferred Stock, and unvested restricted common stock subject to repurchase, as well as RSUs, and PRSUs and options outstanding under the Company’s stock option plans. For all periods presented, there is no difference in the number of shares used to calculate basic and diluted shares outstanding. Net loss allocable to common shares for the six months ended June 30, 2020 includes a one-time, non-cash deemed dividend of $2.8 million resulting from the recognition of a beneficial conversion feature. See Note 5 to our financial statements for additional information. The following table sets forth the outstanding potentially dilutive securities that have been excluded in the calculation of diluted net loss per share because to do so would be anti-dilutive (in common stock equivalent shares): Three and Six Months Ended 2020 2019 Common stock warrants 12,517,328 12,517,328 Series X Convertible Preferred stock 10,965,190 5,652,310 Common stock options, RSUs and PRSUs issued and outstanding 6,665,426 5,690,778 Total 30,147,944 23,860,416 Fair Value of Financial Instruments The Company follows ASC 820-10 issued by the FASB with respect to fair value reporting for financial assets and liabilities. The guidance defines fair value, provides guidance for measuring fair value and requires certain disclosures. The guidance does not apply to measurements related to share-based payments. The guidance discusses valuation techniques, such as the market approach (comparable market prices), the income approach (present value of future income or cash flow), and the cost approach (cost to replace the service capacity of an asset or replacement cost). The guidance establishes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value into three broad levels. The Company’s financial instruments consist of cash and cash equivalents, restricted cash, accounts receivable, prepaid expenses, accounts payable, accrued liabilities, a contingent forward purchase obligation, and long-term debt. Fair value estimates of these instruments are made at each reporting period end based on relevant market information. These estimates may be subjective in nature and involve uncertainties and matters of significant judgment and therefore cannot be determined with precision. The carrying amount of cash and cash equivalents, restricted cash, accounts receivable, prepaid expenses, accounts payable, and accrued liabilities are generally considered to be representative of their respective fair values because of the short-term nature of those instruments. The fair value of contingent forward purchase obligations is based on a probability-weighted valuation approach (See Note 3). The Company believes that the fair value of long-term debt approximates its carrying value. Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of expenses during the reporting period. The Company evaluates its estimates and assumptions on an ongoing basis. The most significant estimates in the Company’s consolidated financial statements relate to estimating the fair value of the Company’s stock options, estimated collaboration expenses and incurred expenses related to the Mundipharma Collaboration Agreement, and certain accruals, including those related to nonclinical and clinical activities. Although the estimates are based on the Company’s knowledge of current events, comparable companies, and actions it may undertake in the future, actual results may ultimately materially differ from these estimates and assumptions. Recently Issued Accounting Standards Recently Issued Accounting Standards Not Yet Adopted In December 2019, the FASB issued ASU 2019-12, "Simplifying the Accounting for Income Taxes," which eliminates certain exceptions within ASC 740, Income Taxes, and clarifies other aspects of the current guidance to promote consistency among reporting entities. The updated guidance is effective for interim and annual periods beginning after December 15, 2020. Early adoption is permitted. The Company does not expect the standard to have a material impact on its financial statements upon adoption. Recently Adopted Accounting Standards In August 2018, the FASB issued ASU 2018-13, "Changes to the Disclosure Requirements for Fair Value Measurement," which modifies certain disclosure requirements on fair value measurements. The Company adopted ASU 2018-13 effective January 1, 2020. The adoption of this standard did not have a material impact on the Company's financial statements. In June 2016, the FASB issued ASU No. 2016-13, "Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments." The updated guidance replaces the incurred loss impairment methodology in current GAAP with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. ASU 2016-13 requires that an entity measure and recognize expected credit losses for financial assets held at amortized cost and replaces the incurred loss impairment methodology in prior GAAP with a methodology that requires consideration of a broader range of information to estimate credit losses, and establishes additional disclosures related to credit risks. For available-for-sale debt securities with unrealized losses, the standard now requires allowances to be recorded instead of reducing the amortized cost of the investment. This standard limits the amount of credit losses to be recognized for available-for-sale debt securities to the amount by which carrying value exceeds fair value and requires the reversal of previously recognized credit losses if fair value increases. The Company adopted ASU 2016-13 effective January 1, 2020. Based on the composition of the Company's financial assets, current economic conditions, historical experience, issuer-specific factors and market data, the adoption of this standard did not have a material impact on the Company's financial statements. The Company will continue to actively monitor the impact of the recent COVID-19 pandemic on expected credit losses.

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	6 Months Ended
	Jun. 30, 2020
Fair Value Disclosures [Abstract]
FAIR VALUE MEASUREMENTS	FAIR VALUE MEASUREMENTS The Company follows ASC 820-10, Fair Value Measurements and Disclosures, which among other things, defines fair value, establishes a consistent framework for measuring fair value and expands disclosure for each major asset and liability category measured at fair value on either a recurring or nonrecurring basis. Fair value is an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement determined based on assumptions that market participants would use in pricing an asset or liability. The carrying amounts of accounts payable and accrued liabilities are considered to be representative of their respective fair values because of the short-term nature of those instruments. Based on the borrowing rates available to the Company for loans with similar terms, which is considered a Level 2 input as described below, the Company believes that the fair value of long-term debt approximates its carrying value. As a basis for considering such assumptions, a three-tier fair value hierarchy has been established, which prioritizes the inputs used in measuring fair value as follows: Level 1: Observable inputs such as quoted prices (unadjusted) in active markets for identical assets or liabilities; Level 2: Inputs, other than the quoted prices in active markets, that are observable either directly or indirectly; and Level 3: Unobservable inputs for which there is little or no market data, which require the reporting entity to develop its own assumptions, which reflect those that a market participant would use. The Company classifies investments in money market funds within Level 1 as the prices are available from quoted prices in active markets. Investments in commercial paper, corporate debt and reverse repurchase agreements are classified within Level 2 as these instruments are valued using observable market inputs including reported trades, broker/dealer quotes, bids and/or offers. As discussed in Note 5, on May 21, 2018, the Company entered into a subscription agreement with certain investors providing for the purchase and sale of up to an aggregate of $120.0 million of its common stock and preferred stock in three closings. The second and optional third closings and warrants related to the optional third closing, which are triggered by the Company's announcement of topline data of Part B of its STRIVE Phase 2 clinical trial of rezafungin, contain features for subsequent closings that are not solely within the control of the Company and that embody an obligation that the Company must settle by issuing a variable number of shares when the obligation is based predominantly on having a fixed value at inception. In accordance with ASC 480, "Distinguishing Liabilities from Equity," the Company determined that these closings are classified as liabilities and represent contingent forward purchase obligations. These liabilities are required to be recorded at their estimated fair value initially and on a recurring basis. The contingent forward purchase obligations are classified within Level 3 of the fair value hierarchy as the Company is using a probability-weighted valuation approach, utilizing significant unobservable inputs including the probability and estimated timing of achieving positive or negative results associated with Part B of the STRIVE Phase 2 clinical trial and estimated discount rates related to the risk of achievement of the expected equity issuances. The liability was initially recorded at $4.3 million on May 21, 2018. Fair value adjustments resulting in a gain of $0.4 million were recorded during the six month period ended June 30, 2019 . The contingent forward purchase obligation did not exist as of June 30, 2020 and December 31, 2019 . None of the Company’s non-financial assets or liabilities are recorded at fair value on a non-recurring basis. No transfers between levels have occurred during the periods presented. The following tables summarize the Company’s financial instruments measured at fair value on a recurring basis (in thousands): TOTAL LEVEL 1 LEVEL 2 LEVEL 3 June 30, 2020 Assets: Cash and money market funds $ 54,826 $ 54,826 $ — $ — Restricted cash and money market accounts 9,259 9,259 — — Total assets at fair value $ 64,085 $ 64,085 $ — $ — December 31, 2019 Assets: Cash and money market accounts $ 50,268 $ 50,268 $ — $ — Restricted cash and money market accounts 10,000 10,000 — — Total assets at fair value $ 60,268 $ 60,268 $ — $ —

DEBT

DEBT	6 Months Ended
	Jun. 30, 2020
Debt Disclosure [Abstract]
DEBT	DEBT Term Loans — On October 3, 2016, the Company entered into a loan and security agreement, or the Loan Agreement, with Pacific Western Bank, as the collateral agent and a lender, or the Lender, pursuant to which the Lender agreed to lend to the Company up to $20.0 million in a series of term loans. Contemporaneously, the Company borrowed $10.0 million from the Lender, or the Term A Loan. Under the terms of the Loan Agreement, because the Company achieved positive clinical results from the STRIVE Phase 2 clinical trial of rezafungin by March 31, 2018, or the Milestone, the Company had the option to borrow, at its sole discretion, until October 3, 2018, from the Lender up to an additional $10.0 million , or the Term B Loan. The Company did not borrow any funds available under the Term B Loan before the draw period ended. The Company’s obligations under the Loan Agreement are secured by a first priority security interest in substantially all of the Company’s current and future assets, other than its intellectual property, which is subject to a double negative pledge. The Company may prepay the borrowed amounts, provided that the Company will be obligated to pay a prepayment fee equal to (i) 2.0% of the applicable principal amount of the Term Loan if the prepayment occurs before the first anniversary of the applicable funding date, and (ii) 1.0% of the applicable principal amount of the Term Loan if the prepayment occurs after the first anniversary of the funding date of such Term Loan but on or prior to the second anniversary of the funding date of such Term Loan. While any amounts are outstanding under the Loan Agreement, the Company is subject to a number of affirmative and restrictive covenants, including covenants regarding dispositions of property, business combinations or acquisitions, incurring additional indebtedness and transactions with affiliates, among other customary covenants. The Company is also restricted from paying dividends or making other distributions or payments on its capital stock, subject to limited exceptions. Pursuant to the Loan Agreement, on October 3, 2016, the Company issued to the Lender a warrant to purchase an aggregate of up to 17,331 shares of the Company’s common stock at an exercise price of $11.54 per share. If the Company borrows additional amounts under the Loan Agreement, it will, in connection with any such borrowing, issue the Lender an additional warrant to purchase that number of shares of the Company’s common stock as is equal to 2.0% of the additional principal amount borrowed divided by the exercise price. The exercise price shall be equal to the 30 -day average closing price of the Company’s common stock, calculated as of the date immediately prior to the date of such additional borrowing. The warrants are immediately exercisable and will expire ten years from the date of the grant. On June 13, 2018, the Company and the Lender entered into a First Amendment to the Loan Agreement, which reset the Milestone to require the Company to achieve positive data from Part B of the STRIVE Phase 2 clinical trial of rezafungin on or prior to July 31, 2019. On July 27, 2018, the Company and the Lender entered into a Second Amendment to the Loan Agreement, which amended, among other things, the interest-only period, the date of maturity, or the Maturity Date, and the interest rate. The interest-only period will be followed by equal monthly payments of principal and interest. The interest-only period will be followed by equal monthly payments of principal and interest. The Term Loans will bear interest at a variable annual rate equal to the greater of (i) 4.5% or (ii) the Lender’s prime interest rate plus 0.75% . At June 30, 2020 , the Term A Loan bears interest at 4.5% . On July 29, 2019, the Company announced positive data from Part B of the STRIVE clinical trial, which satisfied the Milestone. Within 30 days of satisfying the Milestone, the Company was required to agree with the Lender on an amendment to the Loan Agreement to define a new financial covenant and/or milestone for fiscal year 2019 and all subsequent fiscal years during the term of the Loan Agreement. On August 27, 2019, the Lender extended the deadline to execute this amendment to October 15, 2019, and on October 11, 2019, the Lender further extended this deadline until November 7, 2019. On November 5, 2019, the Company and the Lender entered into a Third Amendment to the Loan Agreement, which reset the operating covenant to require the Company to maintain cash equal to or greater than the Company's outstanding indebtedness to the Lender, which is equivalent to a compensating balance and results in a restricted cash balance of $9.3 million and $10.0 million as of June 30, 2020 and December 31, 2019 , respectively. The amendment also extended the interest-only period through April 3, 2020 and the maturity date through July 3, 2022. The Company evaluated the First, Second and Third Amendments to determine whether the amendments represented modifications or extinguishment of debt. The Company determined that the amendments did not represent a substantial change from the original Loan Agreement and accounted for the amendments as debt modifications. Costs previously deferred under the original terms of the Loan Agreement are amortized into interest expense over the new term of the Second Amendment. Upon the occurrence of certain events, including but not limited to the Company’s failure to satisfy its payment obligations under the Loan Agreement, the breach of certain of its other covenants under the Loan Agreement or the occurrence of a material adverse change, the Lender has the right, among other remedies, to declare all principal and interest and other amounts due to the Lender under the Loan Agreement immediately due and payable. The principal payments due under the Loan Agreement have been classified as a current liability at June 30, 2020 and December 31, 2019 due to the considerations discussed in Note 1 and the assessment that the material adverse change clause under the Loan Agreement is not within the Company's control. The Company has not been notified of an event of default by the Lenders as of the date of the filing of this Form 10-Q. As of June 30, 2020 , future principal payments due under the Third Amendment of the Term A Loan are as follows (in thousands): Year ended: December 31, 2020 $ 2,222 December 31, 2021 4,444 December 31, 2022 2,593 Total future principal payments due under the Term A Loan $ 9,259

STOCKHOLDERS_ EQUITY

STOCKHOLDERS’ EQUITY	6 Months Ended
	Jun. 30, 2020
Equity [Abstract]
STOCKHOLDERS’ EQUITY	STOCKHOLDERS’ EQUITY 2020 Rights Offering On January 22, 2020, the Company initiated a rights offering to raise gross proceeds of $30.0 million through the distribution of subscription rights to holders of its common stock, Series X Preferred Stock, and warrants to purchase common stock issued on May 21, 2018, or the Rights Offering. On February 12, 2020, the Company sold 6,639,307 shares of common stock and 531,288 shares of Series X Preferred Stock for $2.51 and $25.10 per share, respectively, for aggregate gross proceeds of $30.0 million . Total offering costs of $0.8 million were offset against the proceeds from the sale of common stock for total net proceeds of $29.2 million . The Rights Offering was fully backstopped by Biotechnology Value Fund, L.P., or BVF, and Stonepine Capital, LP, or Stonepine. With respect to the Series X Convertible Preferred Stock, because the effective conversion price on the commitment date was below the fair value of the common stock at the date of issuance, a beneficial conversion feature with a calculated fair value of $2.8 million existed at the issuance date. As the Series X Convertible Preferred stock is fully convertible at issuance, the full $2.8 million was recorded at issuance as a one-time deemed dividend on February 12, 2020 . This one-time, non-cash deemed dividend impacted accumulated deficit and additional paid in capital at June 30, 2020 and net loss attributable to common stockholders and net loss attributable to common stockholders per share for the six months ended June 30, 2020 . With respect to the common stock, because the purchase price was below fair value on the issuance date, a bonus element exists at the issuance date. Basic and diluted net loss per common share and shares used to compute basic and diluted net loss per common share have been retroactively adjusted for all periods presented to reflect this bonus element. Mundipharma Stock Purchase Agreement On September 3, 2019, the Company entered into a Stock Purchase Agreement, or the Purchase Agreement, with Mundipharma AG, or the Purchaser, a related party, pursuant to which the Company issued to the Purchaser 4,781,408 shares of its common stock, or the Shares, in a private placement at a price per share of $1.884 (a 20% premium to the volume weighted average price of the Company’s common stock for the 10 trading days prior to September 3, 2019) for an aggregate purchase price of approximately $9.0 million . Under the Purchase Agreement, until September 3, 2020, or the Lock-Up Period, the Purchaser may not transfer or sell the Shares without the prior written consent of the Company. In addition, pursuant to the terms of the Stock Purchase Agreement, the Company filed a registration statement with the U.S. Securities and Exchange Commission, or the SEC, to register for resale the 4,781,408 shares of common stock purchased by the Purchaser. May 2018 Registered Direct Offering On May 21, 2018, the Company entered into a subscription agreement with certain investors providing for the purchase and sale, in a registered direct offering, of up to an aggregate of $120.0 million of its common stock and preferred stock in three closings. On May 23, 2018, the Company completed the first closing, which was comprised of 6,185,987 shares of common stock at an offering price of $4.70 per share, 445,231 shares of Series X Convertible Preferred Stock at an offering price of $47.00 per share, and an option fee relating to the third closing paid by the investors for a total of $0.5 million . In a private placement concurrent with the first closing, or the First Private Placement, the Company also sold warrants, at $0.125 per warrant share, to purchase an aggregate of 12,499,997 shares of common stock. Net proceeds for the first closing and the First Private Placement were $49.5 million . The Company performed an analysis to allocate the proceeds from the May 2018 registered direct offering to the offering's various components on a relative fair value basis, including the contingent forward purchase obligations (discussed further in Note 3) as well as the common stock, Series X Convertible Preferred Stock, warrants, and option fee. With respect to the Series X Convertible Preferred Stock, because the adjusted conversion price on the commitment date (following the allocation of proceeds on a fair value basis) was below the fair value of the common stock at the date of issuance, a beneficial conversion feature with a calculated fair value of $10.3 million existed at the issuance date. The beneficial conversion feature is amortized as a deemed dividend to the preferred holders. As the Series X Convertible Preferred Stock is fully convertible at issuance, the full amortization of the $10.3 million was recorded at issuance as a one-time, non-cash deemed dividend on May 23, 2018. The second closing of the registered direct offering was contingent on the Company’s announcement of topline data from Part B of its STRIVE global randomized Phase 2 clinical trial of rezafungin provided that the Company would not be obligated to complete the second closing if the purchase price was less than $4.70 per share, and the third closing of the registered direct offering was to occur after the second closing, but at the Company’s option. On July 29, 2019, the Company announced positive data from Part B of its STRIVE clinical trial. Because the volume weighted average price of the Company's common stock for the five trading days following the public release of topline data from Part B of the STRIVE clinical trial of rezafungin was below $6.27 , the resulting purchase price for the second and third closings of the May 2018 registered direct offering would have been less than $4.70 per share. Accordingly, the Company was unable to complete the second and third closings without first obtaining the approval of its stockholders. On August 7, 2019, the Company notified the purchasers in the May 2018 registered direct offering that it had elected not to consummate the second closing of the offering. Accordingly, the obligations of the parties to the registered direct offering terminated and are of no further force or effect, and the second closing will not be held. As a result of this election, the optional third closing of the offering and the related concurrent private placement of warrants will not be held.​ Preferred Stock Under the amended and restated certificate of incorporation, the Company’s board of directors has the authority, without further action by the stockholders, to issue up to 10,000,000 shares of preferred stock in one or more series, to establish from time to time the number of shares to be included in each such series, to fix the rights, preferences and privileges of the shares of each wholly unissued series and any qualifications, limitations or restrictions thereon and to increase or decrease the number of shares of any such series, but not below the number of shares of such series then outstanding. The Company had 10,000,000 shares of preferred stock authorized at June 30, 2020 . In May 2018, the Company designated 5,000,000 shares of preferred stock as Series X Convertible Preferred Stock with a par value of $0.0001 per share. As of June 30, 2020 , 1,096,519 shares of Series X Convertible Preferred Stock were issued and outstanding. On March 22, 2019, the Company entered into an Exchange Agreement with BVF, and certain of its affiliated entities, pursuant to which BVF and certain of its affiliates, without monetary consideration, agreed to exchange an aggregate of 1,200,000 shares of the Company’s common stock for an aggregate of 120,000 shares of the Company’s Series X Convertible Preferred Stock. The specific terms of the Series X Convertible Preferred Stock are as follows: Conversion: Each share of Series X Convertible Preferred Stock is convertible at the option of the holder into 10 shares of common stock. Holders are not permitted to convert Series X Convertible Preferred Stock into common stock if, after conversion, the holder, its affiliates, and any other person whose beneficial ownership of common stock would be aggregated with the holder's for purposes of Section 13(d) or Section 16 of the Exchange Act, would beneficially own more than 9.99% of the number of shares of common stock outstanding immediately after the conversion. Dividends: Holders of Series X Convertible Preferred Stock are not entitled to receive any dividends except to the extent that dividends are paid on the Company's common stock. If dividends are paid on shares of common stock, holders of Series X Convertible Preferred Stock are entitled to participate in such dividends on an as-converted basis. Liquidation: Upon the liquidation, dissolution, or winding up of the company, each holder of Series X Convertible Preferred Stock will participate pari passu with any distribution of proceeds to holders of common stock. Voting: Shares of Series X Convertible Preferred Stock will generally have no voting rights, except as required by law and except that the consent of the holders of a majority of the outstanding Series X Convertible Preferred Stock will be required to amend the terms of the Series X Convertible Preferred Stock, if such action would adversely alter or change the preferences, rights, privileges or powers of, or restrictions provided for the benefit of the Series X Convertible Preferred Stock, or to increase or decrease (other than by conversion) the number of authorized shares of Series X Convertible Preferred Stock. The Company evaluated the Series X Convertible Preferred Stock for liability or equity classification under ASC 480, "Distinguishing Liabilities from Equity," and determined that equity treatment was appropriate because the Series X Convertible Preferred Stock did not meet the definition of the liability instruments defined thereunder as convertible instruments. Specifically, the Series X Convertible Preferred Stock does not meet the criteria for classification as an ASC 480 liability. As such, the Series X Convertible Preferred Stock is recorded as permanent equity. Additionally, the Series X Convertible Preferred Stock is not redeemable for cash or other assets (i) on a fixed or determinable date, (ii) at the option of the holder, and (iii) upon the occurrence of an event that is not solely within control of the Company. Common Stock The Company had 200,000,000 shares of common stock authorized as of June 30, 2020 . Holders of outstanding shares of common stock are entitled to one vote for each share held of record on all matters submitted to a vote of the holders of common stock. Subject to the rights of the holders of any class of the Company’s capital stock having any preference or priority over common stock, the holders of common stock are entitled to receive dividends that are declared by the Company’s board of directors out of legally available funds. In the event of a liquidation, dissolution or winding-up, the holders of common stock are entitled to share ratably in the net assets remaining after payment of liabilities, subject to prior rights of preferred stock, if any, then outstanding. The common stock has no preemptive rights, conversion rights, redemption rights or sinking fund provisions, and there are no dividends in arrears or default. All shares of common stock have equal distribution, liquidation and voting rights, and have no preferences or exchange rights. In September 2019, the Company began to sell shares of common stock under a controlled equity sales agreement with Cantor Fitzgerald & Co. During the six months ended June 30, 2020 , the company sold 1,334,369 shares for net proceeds of approximately $4.7 million , after deducting placement agent fees. Common Stock Warrants As of June 30, 2020 and December 31, 2019 , warrants to purchase 12,517,328 shares of common stock were outstanding at a weighted average exercise price of $6.82 per share. Common Stock Reserved for Future Issuance Common stock reserved for future issuance is as follows (in common stock equivalent shares): June 30, 2020 December 31, 2019 Common stock warrants 12,517,328 12,517,328 Series X Convertible Preferred Stock 10,965,190 5,652,310 Common stock options, RSUs and PRSUs issued and outstanding 6,665,426 5,360,563 Authorized for future stock awards under the Company's option plans 2,190,815 559,898 Authorized for future issuance under the ESPP 669,210 463,741 Total 33,007,969 24,553,840

EQUITY INCENTIVE PLANS

EQUITY INCENTIVE PLANS	6 Months Ended
	Jun. 30, 2020
Share-based Payment Arrangement [Abstract]
EQUITY INCENTIVE PLANS	EQUITY INCENTIVE PLANS 2015 Equity Incentive Plan In March 2015, the Company’s board of directors and stockholders approved and adopted the 2015 Equity Incentive Plan, or the 2015 EIP. Under the 2015 EIP, the Company may grant stock options, stock appreciation rights, restricted stock, RSUs, and other awards to individuals who are employees, officers, directors, or consultants of the Company. The number of shares of stock available for issuance under the 2015 EIP will be automatically increased each January 1 by 4% of the outstanding number of shares of the Company’s common stock on the immediately preceding December 31 or such lesser number as determined by the Company’s board of directors. Terms of stock award agreements, including vesting requirements, are determined by the board of directors, subject to the provisions of the 2015 EIP. Stock options granted by the Company generally vest over a three - or four -year period. Certain stock options are subject to acceleration of vesting in the event of certain change of control transactions. The stock options may be granted for a term of up to 10 years from the date of grant. The exercise price for stock options granted under the 2015 EIP must be at a price no less than 100% of the estimated fair value of the shares on the date of grant as determined by the board of directors, provided that for an incentive stock option granted to an employee who at the time of grant owns stock representing more than 10% of the voting power of all classes of stock of the Company, the exercise price shall be no less than 110% of the estimated value on the date of grant. 2015 Employee Stock Purchase Plan In March 2015, the Company’s board of directors and stockholders approved and adopted the 2015 Employee Stock Purchase Plan, or the ESPP. The number of shares of stock available for issuance under the ESPP will be automatically increased each January 1 by the lesser of (i) 1% of the outstanding number of shares of the Company’s common stock on the immediately preceding December 31, (ii) 490,336 shares, or (iii) such lesser number as determined by the Company’s board of directors. The ESPP allows substantially all employees to purchase the Company’s common stock through a payroll deduction at a price equal to 85% of the lower of the fair market value of the stock as of the beginning or the end of each purchase period. An employee’s payroll deductions under the ESPP are limited to 15% of the employee’s eligible compensation. During the three and six months ended June 30, 2020 , 132,915 shares were issued pursuant to the ESPP. Restricted Stock Units The following table summarizes RSU and PRSU activity during the six months ended June 30, 2020 : Number of Outstanding at December 31, 2019 383,885 RSUs and PRSUs granted 125,975 RSUs and PRSUs vested (72,304 ) RSUs and PRSUs canceled (21,880 ) Outstanding at June 30, 2020 415,676 Stock-based compensation expense related to RSUs and PRSUs was approximately $0.1 million and $0.2 million , respectively, for the three and six months ended June 30, 2020 , and $0.1 million and $0.1 million , respectively, for the three and six months ended June 30, 2019 . At June 30, 2020 , estimated unrecognized compensation expense related to RSUs and PRSUs grants was approximately $1.2 million . Stock Options The following table summarizes stock option activity during the six months ended June 30, 2020 : Number of Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Life in Years Total Aggregate Intrinsic Value (in thousands) Outstanding at December 31, 2019 4,976,678 $ 4.37 7.27 $ 3,880 Options granted 1,579,500 2.13 Options exercised (1,834 ) 2.61 Options canceled (304,594 ) 8.15 Outstanding at June 30, 2020 6,249,750 $ 3.62 7.52 $ 5,890 Vested and expected to vest at June 30, 2020 6,249,750 $ 3.62 7.52 $ 5,890 Exercisable at June 30, 2020 2,512,826 $ 5.32 6.57 $ 1,222 The intrinsic value of a stock option is the difference between the market price of the common stock at the measurement date and the exercise price of the option. Stock-based compensation expense recognized for restricted shares, RSUs, PRSUs, stock options, and the ESPP has been reported in the statements of operations as follows (in thousands): Three Months Ended Six Months Ended 2020 2019 2020 2019 Research and development $ 528 $ 654 $ 1,129 $ 1,297 General and administrative 467 603 1,112 1,244 Total $ 995 $ 1,257 $ 2,241 $ 2,541 The weighted-average grant date fair value of stock options granted by the Company during the six months ended June 30, 2020 was $1.47 per share. As of June 30, 2020 , total unrecognized share-based compensation expense related to unvested stock options was approximately $4.9 million . This unrecognized compensation cost is expected to be recognized over a weighted-average period of approximately 1.71 years. As of June 30, 2020 , total unrecognized compensation expense related to the ESPP was approximately $0.2 million . This unrecognized compensation cost is expected to be recognized over approximately 0.5 years .

SIGNIFICANT AGREEMENTS AND CONT

SIGNIFICANT AGREEMENTS AND CONTRACTS	6 Months Ended
	Jun. 30, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
SIGNIFICANT AGREEMENTS AND CONTRACTS	SIGNIFICANT AGREEMENTS AND CONTRACTS Mundipharma Collaboration Agreement On September 3, 2019, the Company entered into the Collaboration Agreement with Mundipharma, a related party, for a strategic collaboration to develop and commercialize rezafungin in an intravenous formulation, or the Licensed Product, for the treatment and prevention of invasive fungal infections. Under the Collaboration Agreement, the Company will be responsible for leading the conduct of an agreed global development plan, or the Global Development Plan, that includes the Company’s ongoing Phase 3 pivotal clinical trial of the Licensed Product for the treatment of candidemia and/or invasive candidiasis, or the ReSTORE Trial, and the Company’s planned Phase 3 pivotal clinical trial of the Licensed Product for the prophylaxis of invasive fungal infections in adult allogeneic blood and marrow transplant recipients, or the ReSPECT Trial, as well as specified GLP-compliant non‑clinical studies and chemistry, manufacturing and controls, or CMC, development activities for the Licensed Product. Mundipharma will be responsible for performing all development activities, other than Global Development Plan activities, that may be necessary to obtain and maintain regulatory approvals for the Licensed Product in the Mundipharma Territory, at Mundipharma’s sole cost. Pursuant to the Collaboration Agreement, the Company granted Mundipharma an exclusive, royalty‑bearing license to develop, register and commercialize the Licensed Product outside of the United States and Japan, or the Mundipharma Territory, subject to the Company’s retained right to lead a global development program for the Licensed Product in both the Mundipharma Territory and in the United States and Japan, or the Company Territory, as described below. The Company also granted Mundipharma an option to obtain exclusive licenses to develop, register and commercialize rezafungin in a formulation for subcutaneous administration, or Subcutaneous Product, and in formulations for other modes of administration, or Other Products, in the Mundipharma Territory, subject to similar retained rights of the Company to conduct mutually agreed global development activities for such products. In addition, the Company granted Mundipharma a co‑exclusive, worldwide license to manufacture the Licensed Product and rezafungin. Until the seventh anniversary of the first commercial sale of the Licensed Product in the Mundipharma Territory, each party has granted the other party an exclusive, time-limited right of first negotiation to obtain a license to any anti-fungal product (other than Licensed Product, Subcutaneous Product and Other Products) that such party proposes to out-license in the other party’s territory. However, in the event of the acquisition of a party by a third party, this right of first negotiation will not apply to any such anti‑fungal product of the acquiring third party prior to consummation of the acquisition of such party, acquired by such acquiring third party from another third party after consummation of the acquisition of such party, or developed internally by the acquiring third party, either before or after consummation of the acquisition of such party, without the use of, reliance upon or reference to any technology of the acquired party that is licensed to the other party under the Collaboration Agreement, any technology of the other party that is licensed to the acquired party under the Collaboration Agreement, or any technology jointly developed by the parties pursuant to the Collaboration Agreement. The Company retains the exclusive right to develop, register and commercialize the Licensed Product, Subcutaneous Product and Other Products in the Company Territory, and Mundipharma has granted the Company certain licenses under Mundipharma-controlled technology and jointly-developed technology to develop, register and commercialize Licensed Product, Subcutaneous Product and Other Products in the Company Territory and to manufacture such products and rezafungin worldwide. The parties have agreed to share equally (50/50) the costs of Global Development Plan activities, or Global Development Costs, subject to a cap on Mundipharma’s Global Development Cost share of $31.2 million . The Company would receive additional financial support for Global Development Plan activities through a near-term milestone payment by Mundipharma of $11.1 million . Mundipharma is entitled to credit the full amount of this milestone payment toward future royalties payable to the Company, subject to a limit on the amount by which royalty payments to the Company may be reduced in any quarter. If Mundipharma has not fully credited the amount of such milestone payment toward royalties payable to the Company before the earlier of (i) December 31, 2024 and (ii) termination of the Collaboration Agreement by Mundipharma, the Company will be obligated to refund the uncredited portion of such milestone payment to Mundipharma on the earlier of such dates. The total potential transaction value is $568 million , including an equity investment (see Note 5), an up-front payment, global development funding, and certain development, regulatory, and commercial milestones. The Company is also eligible for double-digit royalties in the teens on tiers of annual net sales. Either party may terminate the Collaboration Agreement for uncured material breach by the other party. After September 3, 2020, Mundipharma may terminate the Collaboration Agreement at will, provided that if Mundipharma terminates the Collaboration Agreement in its entirety prior to the last visit of the last patient in both the ReSPECT Trial and the ReSTORE Trial, Mundipharma will continue to be liable for its share of Global Development Costs as described above. The Company may terminate the Agreement if Mundipharma or any of its affiliates or sublicensees, directly or indirectly through any third party, commences any interference or opposition proceeding with respect to, challenges the validity or enforceability of, or opposes any extension of or the grant of a supplementary protection certificate with respect to, any of the Company's patent rights licensed to Mundipharma, or upon an insolvency event of Mundipharma. Revenue Recognition The Company determined the transaction price is equal to the up-front fee of $30.0 million plus the research and development funding of $31.2 million . The price paid for the common stock was determined to be at fair market value after applying a lack of marketability discount as Mundipharma received restricted shares. Therefore, no additional premium or discount was allocated to the transaction price of the Agreement for the share issuance. The transaction price was allocated to the performance obligations on the basis of the relative stand-alone selling price estimated for each performance obligation. In estimating the stand-alone selling price for each performance obligation, the Company developed assumptions that require judgment and included forecasted revenues, expected development timelines, discount rates, probabilities of technical and regulatory success and costs for manufacturing clinical supplies. A description of the distinct performance obligations identified under the Agreement, as well as the amount of revenue allocated to each distinct significant performance obligation, is as follows: Licenses of Intellectual Property. The license to the Company’s intellectual property, bundled with the associated know-how, represents a distinct performance obligation. The license and associated know-how was transferred to Mundipharma during September 2019, therefore the Company recognized the full revenue related to this performance obligation in the amount of $17.9 million in September 2019 as license revenue in its condensed consolidated statements of operations and comprehensive income. Research and Development Services. The Company and Mundipharma share equally in the costs of ongoing rezafungin clinical development in the Licensed Territory up to the specified cap. The Company records these cost-sharing payments due from Mundipharma as collaboration revenue. The Company concluded that progress towards completion of the performance obligation related to the research and development services is best measured in an amount proportional to the research and development expenses incurred and the total estimated research and development expenses. Clinical Supply Services. The Company's initial obligation to supply rezafungin for ongoing clinical development in the Licensed Territory represents a distinct performance obligation. The Company concluded that progress towards completion of the performance obligations related to the clinical supply services is best measured in an amount proportional to the clinical supply services expenses incurred and the total estimated clinical supply services. Milestone Payments. The Company determined that as of June 30, 2020 , all the potential milestone payments are probable of significant revenue reversal as their achievement is highly dependent on factors outside the Company's control or are otherwise constrained under the variable consideration guidance. Therefore, these payments have been fully constrained and are therefore not included in the transaction price. At the end of each subsequent reporting period, the Company will re-evaluate the probability of achievement of each milestone and any related constraint. Royalties. As the license is deemed to be the predominant item to which sales-based royalties relate, the Company will recognize revenue when the related sales occur. No royalty revenue was recognized during the six months ended June 30, 2020 . The following table presents a summary of the activity in the Company's contract liabilities (recorded as deferred revenue on the balance sheet) during the six months ended June 30, 2020 (in thousands): Opening balance, December 31, 2019 $ 9,803 Payments received in advance 7,315 Revenue from performance obligations satisfied during reporting period (5,922 ) Closing balance, June 30, 2020 $ 11,196 The closing balance as of June 30, 2020 are classified as a current liability since the rights to consideration are expected to be satisfied within one year. The following table presents our contract revenues disaggregated by timing of revenue recognition and excludes royalty revenue (in thousands): Three Months Ended Six Months Ended June 30, 2020 Point in Time Over Time Point in Time Over Time Revenue from Mundipharma Collaboration Agreement: Research and Development Services $ — $ 3,182 $ — $ 5,174 Clinical Supply Services — 210 — 748 Total revenue from Mundipharma Collaboration Agreement $ — $ 3,392 $ — $ 5,922

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	6 Months Ended
	Jun. 30, 2020
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES Lease Obligations The following table presents information about the amount, timing and uncertainty of cash flows arising from the Company's operating lease as of June 30, 2020 (in thousands): 2020 $ 484 2021 998 Total undiscounted operating lease payments $ 1,482 Less: Imputed interest (120 ) Present value of lease payments $ 1,362 The balance sheet classification of the Company's operating lease is as follows (in thousands): Balance Sheet Classification: Operating lease right-of-use asset $ 1,257 Current lease liability $ 878 Lease liability 484 Total operating lease liability $ 1,362 As of June 30, 2020 , the weighted average remaining lease term was 1.5 years . Cash paid for amounts included in the present value of operating lease liabilities was $0.5 million for the six months ended June 30, 2020 . Operating lease costs were $0.5 million for the six months ended June 30, 2020 . These costs are primarily related to the Company's long-term operating lease, but also include immaterial amounts for variable leases and short-term leases with terms greater than 30 days. Contractual Obligations The Company enters into contracts in the normal course of business with vendors for research and development activities, manufacturing, and professional services. These contracts generally provide for termination either on notice or after a notice period.

SUMMARY OF SIGNIFICANT ACCOUN_2

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	6 Months Ended
	Jun. 30, 2020
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The Company has a limited operating history and the sales and income potential of the Company’s business and market are unproven. The Company has experienced net losses and negative cash flows from operating activities since its inception. At June 30, 2020 , the Company had an accumulated deficit of $295.4 million . The Company expects to continue to incur net losses into the foreseeable future. Successful transition to attaining profitable operations is dependent upon achieving a level of revenues adequate to support the Company’s cost structure. At June 30, 2020 , the Company had cash, cash equivalents and restricted cash of $64.1 million . Based on the Company’s current business plan, management believes that existing cash and cash equivalents will not be sufficient to fund the Company’s obligations for twelve months from the issuance of these financial statements. The Company’s ability to execute its operating plan depends on its ability to obtain additional funding through equity offerings, debt financings or potential licensing and collaboration arrangements. The accompanying consolidated financial statements have been prepared assuming the Company will continue as a going concern, which contemplates the realization of assets and settlement of liabilities in the normal course of business. However, the Company’s current working capital, anticipated operating expenses and net losses and the uncertainties surrounding its ability to raise additional capital as needed, as discussed below, raise substantial doubt about its ability to continue as a going concern for a period of one year following the date that these financial statements are issued. The consolidated financial statements do not include any adjustments for the recovery and classification of assets or the amounts and classification of liabilities that might be necessary should the Company be unable to continue as a going concern. The Company plans to continue to fund its losses from operations through cash and cash equivalents on hand, as well as through future equity offerings, debt financings, other third party funding, and potential licensing or collaboration arrangements. There can be no assurance that additional funds will be available when needed from any source or, if available, will be available on terms that are acceptable to the Company. Even if the Company raises additional capital, it may also be required to modify, delay or abandon some of its plans which could have a material adverse effect on the Company’s business, operating results and financial condition and the Company’s ability to achieve its intended business objectives. Any of these actions could materially harm the Company’s business, results of operations and future prospects. In addition to the foregoing, the Company is monitoring closely the impact of the COVID-19 pandemic on its business and has taken steps designed to protect the health and safety of its employees while continuing its operations. Given the level of uncertainty regarding the duration and impact of the COVID-19 pandemic on capital markets and the U.S. economy, the Company is currently unable to assess the impact of the COVID-19 pandemic on its future access to capital. The Company is continuing to monitor the spread of COVID-19 and its potential impact on the Company's operations. The full extent to which the COVID-19 pandemic will impact the Company's business, results of operations, financial condition, clinical trials, and preclinical research will depend on future developments that are highly uncertain, including actions taken to contain or treat COVID-19 and their effectiveness, as well as the economic impact on national and international markets.
Unaudited Interim Financial Data	Unaudited Interim Financial Data The accompanying condensed consolidated financial statements are unaudited and have been prepared by the Company in accordance with U.S. generally accepted accounting principles, or GAAP, as found in the Accounting Standards Codification, or ASC, of the Financial Accounting Standards Board, or FASB. Certain information and footnote disclosures normally included in the Company’s annual financial statements have been condensed or omitted. These interim condensed consolidated financial statements, in the opinion of management, reflect all normal recurring adjustments necessary for a fair presentation of the Company’s financial position and results of operations for the interim periods ended June 30, 2020 and 2019 .
Basis of Consolidation	Basis of Consolidation The consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. All significant intercompany accounts and transactions have been eliminated in consolidation.
Segment Information	Segment Information Operating segments are identified as components of an enterprise about which separate discrete financial information is available for evaluation by the chief operating decision maker, the Chief Executive Officer, in making decisions regarding resource allocation and assessing performance. The Company views its operations and manages its business as one operating segment.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers all short-term investments purchased with a maturity of three months or less when acquired to be cash equivalents. Restricted cash represents cash that the Company is required to maintain on hand in order to maintain compliance with an operating covenant in the Third Amendment to the Company's Loan Agreement with Pacific Western Bank. See Note 4 for more information.
Concentration of Credit Risk	Concentration of Credit Risk The Company’s financial instruments that are exposed to concentrations of credit risk consist primarily of cash and cash equivalents. The Company maintains deposits in government insured financial institutions in excess of government insured limits. The Company invests its cash balances in financial institutions that it believes have high credit quality, has not experienced any losses on such accounts and does not believe it is exposed to significant credit risk.
Patent Costs	Patent Costs The Company expenses all costs as incurred in connection with patent applications (including direct application fees, and the legal and consulting expenses related to making such applications), and such costs are included in general and administrative expenses in the accompanying statements of operations.
Income Taxes	Income Taxes The Company follows the FASB's ASC 740, Income Taxes, in reporting deferred income taxes. ASC 740 requires a company to recognize deferred tax assets and liabilities for expected future income tax consequences of events that have been recognized in the Company’s consolidated financial statements. Under this method, deferred tax assets and liabilities are determined based on temporary differences between financial statement carrying amounts and the tax basis of assets and liabilities using enacted tax rates in the years in which the temporary differences are expected to reverse. Valuation allowances are provided if, based on the weight of available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. The Company accounts for uncertain tax positions pursuant to ASC 740, which prescribes a recognition threshold and measurement process for financial statement recognition of uncertain tax positions taken or expected to be taken in a tax return. If the tax position meets this threshold, the benefit to be recognized is measured as the tax benefit having the highest likelihood of being realized upon ultimate settlement with the taxing authority. The Company recognizes interest accrued related to unrecognized tax benefits and penalties in the provision for income taxes.
Revenue Recognition	Revenue Recognition The Company recognizes revenue is accordance with Accounting Standards Codification, or ASC, Topic 606, Revenue from Contracts with Customers, which applies to all contracts with customers, except for contracts that are within the scope of other standards, such as leases, insurance, collaboration arrangements and financial instruments. Under Topic 606, an entity recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration that 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 the consideration it is entitled to in exchange for the goods or services it transfers to the customer. At contract inception, once the contract is determined to be within the scope of Topic 606, the Company assesses the goods or services promised within each contract and determines those that are performance obligations, and assesses whether each promised good or service is distinct. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) the performance obligation is satisfied. In a contract with multiple performance obligations, the Company must develop estimates and assumptions that require judgment to determine the underlying stand-alone selling price for each performance obligation, which determines how the transaction price is allocated among the performance obligations. The estimation of the stand-alone selling price(s) may include estimates regarding forecasted revenues or costs, development timelines, discount rates, and probabilities of technical and regulatory success. The Company evaluates each performance obligation to determine if it can be satisfied at a point in time or over time. Any change made to estimated progress towards completion of a performance obligation and, therefore, revenue recognized will be recorded as a change in estimate. In addition, variable consideration must be evaluated to determine if it is constrained and, therefore, excluded from the transaction price. If a license to the Company’s intellectual property is determined to be distinct from the other performance obligations identified in a contract, the Company recognizes revenues from the transaction price allocated to the license when the license is transferred to the licensee and the licensee is able to use and benefit from the license. For licenses that are bundled with other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue from the allocated transaction price. The Company evaluates the measure of progress at each reporting period and, if necessary, adjusts the measure of performance and related revenue or expense recognition as a change in estimate. At the inception of each arrangement that includes milestone payments, the Company evaluates whether the milestones are considered probable of being reached. If it is probable that a significant revenue reversal would not occur, the associated milestone value is included in the transaction price. Milestone payments that are not within the Company’s or a collaboration partner’s control, such as regulatory approvals, are generally not considered probable of being achieved until those approvals are received. At the end of each reporting period, the Company re-evaluates the probability of achievement of milestones that are within its or a collaboration partner’s control, such as operational developmental milestones and any related constraint, and, if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which will affect collaboration revenues and earnings in the period of adjustment. Revisions to the Company’s estimate of the transaction price may also result in negative collaboration revenues and earnings in the period of adjustment. For arrangements that include sales-based royalties, including commercial milestone payments based on the level of sales, and a license is deemed to be the predominant item to which the royalties relate, the Company will recognize revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied, or partially satisfied. To date, the Company has not recognized any royalty revenue from collaborative arrangements. In September 2019, the Company entered into a Collaboration and License Agreement, or the Collaboration Agreement, with Mundipharma Medical Company, or Mundipharma. The Company concluded that there were three significant performance obligations under the Collaboration Agreement: the license, the research and development services, and the clinical supply services, and that the obligations are distinct from each other. Revenue associated with the license was recognized upon delivery in September 2019. The Company concluded that progress towards completion of the research and development and clinical supply performance obligations related to the Collaboration Agreement is best measured in an amount proportional to the collaboration expenses incurred and the total estimated collaboration expenses. The Company periodically reviews and updates the estimated collaboration expenses, when appropriate, which may adjust revenue recognized for the period. While such changes to the Company’s estimates have no impact on the Company’s reported cash flows, the amount of revenue recorded in the period could be materially impacted. The transaction price to be recognized as revenue under the Collaboration Agreement consists of the upfront payment and estimated reimbursable research and development and clinical supply costs. Potential future payments for variable consideration, such as clinical, regulatory or commercial milestones, will be recognized when it is probable that, if recorded, a significant reversal will not take place. Potential future royalty payments will be recorded as revenue when the associated sales occur.
Grant Funding and Research and Development Costs	Grant Funding The Company has evaluated the terms of the research and development grants to assess its obligations and the classification of funding received. Amounts billable for funded research and development are recognized in the statement of operations as a reduction to research and development expense over the grant period as the related costs are incurred to meet the Company's obligations. Research and Development Costs Research and development expenses consist of wages, benefits and stock-based compensation charges for research and development employees, scientific consultant fees, facilities and overhead expenses, laboratory supplies, manufacturing expenses, and nonclinical and clinical trial costs. The Company accrues nonclinical and clinical trial expenses based on work performed, which relies on estimates of total costs incurred based on patient enrollment, completion of studies, and other events.
Preclinical and Clinical Trial Accruals	Preclinical and Clinical Trial Accruals The Company makes estimates of its accrued expenses as of each balance sheet date in the financial statements based on the facts and circumstances known at that time. Accrued expenses for preclinical studies and clinical trials are based on estimates of costs incurred and fees that may be associated with services provided by contract research organizations, or CROs, clinical trial investigational sites and other clinical trial-related activities. Payments under certain contracts with such parties depend on factors such as successful enrollment of patients, site initiation and the completion of clinical trial milestones. In accruing for these services, the Company estimates the time period over which services will be performed and the level of effort to be expended in each period. If possible, the Company obtains information regarding unbilled services directly from these service providers. However, the Company may be required to estimate these services based on other available information. If the Company underestimates or overestimates the activities or fees associated with a study or service at a given point in time, adjustments to research and development expenses may be necessary in future periods. Historically, estimated accrued liabilities have approximated actual expense incurred. Subsequent changes in estimates may result in a material change in accruals.
Stock-based Compensation	Stock-based Compensation The Company accounts for stock-based compensation expense related to stock options and employee stock purchase plan rights by estimating the fair value on the date of grant using the Black-Scholes option pricing model. The fair value of Restricted Stock Units, or RSUs, and Performance-based RSUs, or PRSUs, is estimated based on the closing price of the Company's common stock on the date of grant. For awards subject to time-based vesting conditions, stock-based compensation expense is recognized ratably over the requisite service period of the awards. For awards subject to performance-based vesting conditions, the Company assesses the probability of achievement of the individual milestones under the stock-based awards and recognizes stock-based compensation expense over the implicit service period commencing once the Company believes the performance criteria is probable of achievement. The Company recognizes forfeitures related to stock-based compensation as they occur.
Net Loss Per Share	Net Loss Per Share Basic net loss per share is calculated by dividing the net loss allocable to common shares by the weighted-average number of common shares outstanding for the period, without consideration for potentially dilutive securities. Diluted net loss per share is computed by dividing the net loss allocable to common shares by the weighted-average number of common shares and dilutive common stock equivalents outstanding for the period determined using the treasury-stock and if-converted methods. Dilutive common stock equivalents are comprised of warrants, Series X Convertible Preferred Stock, and unvested restricted common stock subject to repurchase, as well as RSUs, and PRSUs and options outstanding under the Company’s stock option plans. For all periods presented, there is no difference in the number of shares used to calculate basic and diluted shares outstanding.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The Company follows ASC 820-10 issued by the FASB with respect to fair value reporting for financial assets and liabilities. The guidance defines fair value, provides guidance for measuring fair value and requires certain disclosures. The guidance does not apply to measurements related to share-based payments. The guidance discusses valuation techniques, such as the market approach (comparable market prices), the income approach (present value of future income or cash flow), and the cost approach (cost to replace the service capacity of an asset or replacement cost). The guidance establishes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value into three broad levels. The Company’s financial instruments consist of cash and cash equivalents, restricted cash, accounts receivable, prepaid expenses, accounts payable, accrued liabilities, a contingent forward purchase obligation, and long-term debt. Fair value estimates of these instruments are made at each reporting period end based on relevant market information. These estimates may be subjective in nature and involve uncertainties and matters of significant judgment and therefore cannot be determined with precision. The carrying amount of cash and cash equivalents, restricted cash, accounts receivable, prepaid expenses, accounts payable, and accrued liabilities are generally considered to be representative of their respective fair values because of the short-term nature of those instruments. The fair value of contingent forward purchase obligations is based on a probability-weighted valuation approach (See Note 3). The Company believes that the fair value of long-term debt approximates its carrying value.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of expenses during the reporting period. The Company evaluates its estimates and assumptions on an ongoing basis. The most significant estimates in the Company’s consolidated financial statements relate to estimating the fair value of the Company’s stock options, estimated collaboration expenses and incurred expenses related to the Mundipharma Collaboration Agreement, and certain accruals, including those related to nonclinical and clinical activities. Although the estimates are based on the Company’s knowledge of current events, comparable companies, and actions it may undertake in the future, actual results may ultimately materially differ from these estimates and assumptions.
Recently Issued Accounting Standards	Recently Issued Accounting Standards Recently Issued Accounting Standards Not Yet Adopted In December 2019, the FASB issued ASU 2019-12, "Simplifying the Accounting for Income Taxes," which eliminates certain exceptions within ASC 740, Income Taxes, and clarifies other aspects of the current guidance to promote consistency among reporting entities. The updated guidance is effective for interim and annual periods beginning after December 15, 2020. Early adoption is permitted. The Company does not expect the standard to have a material impact on its financial statements upon adoption. Recently Adopted Accounting Standards In August 2018, the FASB issued ASU 2018-13, "Changes to the Disclosure Requirements for Fair Value Measurement," which modifies certain disclosure requirements on fair value measurements. The Company adopted ASU 2018-13 effective January 1, 2020. The adoption of this standard did not have a material impact on the Company's financial statements. In June 2016, the FASB issued ASU No. 2016-13, "Financial Instruments - Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments." The updated guidance replaces the incurred loss impairment methodology in current GAAP with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. ASU 2016-13 requires that an entity measure and recognize expected credit losses for financial assets held at amortized cost and replaces the incurred loss impairment methodology in prior GAAP with a methodology that requires consideration of a broader range of information to estimate credit losses, and establishes additional disclosures related to credit risks. For available-for-sale debt securities with unrealized losses, the standard now requires allowances to be recorded instead of reducing the amortized cost of the investment. This standard limits the amount of credit losses to be recognized for available-for-sale debt securities to the amount by which carrying value exceeds fair value and requires the reversal of previously recognized credit losses if fair value increases. The Company adopted ASU 2016-13 effective January 1, 2020. Based on the composition of the Company's financial assets, current economic conditions, historical experience, issuer-specific factors and market data, the adoption of this standard did not have a material impact on the Company's financial statements. The Company will continue to actively monitor the impact of the recent COVID-19 pandemic on expected credit losses.

SUMMARY OF SIGNIFICANT ACCOUN_3

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)	6 Months Ended
	Jun. 30, 2020
Accounting Policies [Abstract]
Summary of Outstanding Potentially Dilutive Securities Excluded from Calculation of Diluted Net Income (Loss) Per Share	The following table sets forth the outstanding potentially dilutive securities that have been excluded in the calculation of diluted net loss per share because to do so would be anti-dilutive (in common stock equivalent shares): Three and Six Months Ended 2020 2019 Common stock warrants 12,517,328 12,517,328 Series X Convertible Preferred stock 10,965,190 5,652,310 Common stock options, RSUs and PRSUs issued and outstanding 6,665,426 5,690,778 Total 30,147,944 23,860,416

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	6 Months Ended
	Jun. 30, 2020
Fair Value Disclosures [Abstract]
Summary of Financial Instruments Measured at Fair Value on a Recurring Basis	The following tables summarize the Company’s financial instruments measured at fair value on a recurring basis (in thousands): TOTAL LEVEL 1 LEVEL 2 LEVEL 3 June 30, 2020 Assets: Cash and money market funds $ 54,826 $ 54,826 $ — $ — Restricted cash and money market accounts 9,259 9,259 — — Total assets at fair value $ 64,085 $ 64,085 $ — $ — December 31, 2019 Assets: Cash and money market accounts $ 50,268 $ 50,268 $ — $ — Restricted cash and money market accounts 10,000 10,000 — — Total assets at fair value $ 60,268 $ 60,268 $ — $ —

DEBT (Tables)

DEBT (Tables)	6 Months Ended
	Jun. 30, 2020
Debt Disclosure [Abstract]
Schedule of Future Principal Payments	As of June 30, 2020 , future principal payments due under the Third Amendment of the Term A Loan are as follows (in thousands): Year ended: December 31, 2020 $ 2,222 December 31, 2021 4,444 December 31, 2022 2,593 Total future principal payments due under the Term A Loan $ 9,259

STOCKHOLDERS_ EQUITY (Tables)

STOCKHOLDERS’ EQUITY (Tables)	6 Months Ended
	Jun. 30, 2020
Equity [Abstract]
Schedule of Common Stock Reserved for Future Issuance	Common stock reserved for future issuance is as follows (in common stock equivalent shares): June 30, 2020 December 31, 2019 Common stock warrants 12,517,328 12,517,328 Series X Convertible Preferred Stock 10,965,190 5,652,310 Common stock options, RSUs and PRSUs issued and outstanding 6,665,426 5,360,563 Authorized for future stock awards under the Company's option plans 2,190,815 559,898 Authorized for future issuance under the ESPP 669,210 463,741 Total 33,007,969 24,553,840

EQUITY INCENTIVE PLANS (Tables)

EQUITY INCENTIVE PLANS (Tables)	6 Months Ended
	Jun. 30, 2020
Share-based Payment Arrangement [Abstract]
Summary of Restricted Stock Units and Performance-based Restricted Stock Units Activity	The following table summarizes RSU and PRSU activity during the six months ended June 30, 2020 : Number of Outstanding at December 31, 2019 383,885 RSUs and PRSUs granted 125,975 RSUs and PRSUs vested (72,304 ) RSUs and PRSUs canceled (21,880 ) Outstanding at June 30, 2020 415,676
Summary of Stock Option Activity	The following table summarizes stock option activity during the six months ended June 30, 2020 : Number of Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Life in Years Total Aggregate Intrinsic Value (in thousands) Outstanding at December 31, 2019 4,976,678 $ 4.37 7.27 $ 3,880 Options granted 1,579,500 2.13 Options exercised (1,834 ) 2.61 Options canceled (304,594 ) 8.15 Outstanding at June 30, 2020 6,249,750 $ 3.62 7.52 $ 5,890 Vested and expected to vest at June 30, 2020 6,249,750 $ 3.62 7.52 $ 5,890 Exercisable at June 30, 2020 2,512,826 $ 5.32 6.57 $ 1,222
Schedule of Stock-based Compensation Expense	Stock-based compensation expense recognized for restricted shares, RSUs, PRSUs, stock options, and the ESPP has been reported in the statements of operations as follows (in thousands): Three Months Ended Six Months Ended 2020 2019 2020 2019 Research and development $ 528 $ 654 $ 1,129 $ 1,297 General and administrative 467 603 1,112 1,244 Total $ 995 $ 1,257 $ 2,241 $ 2,541

SIGNIFICANT AGREEMENTS AND CO_2

SIGNIFICANT AGREEMENTS AND CONTRACTS (Tables)	6 Months Ended
	Jun. 30, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Summary of collaborative agreement liabilities and revenues disaggregated by timing of revenue recognition	The following table presents our contract revenues disaggregated by timing of revenue recognition and excludes royalty revenue (in thousands): Three Months Ended Six Months Ended June 30, 2020 Point in Time Over Time Point in Time Over Time Revenue from Mundipharma Collaboration Agreement: Research and Development Services $ — $ 3,182 $ — $ 5,174 Clinical Supply Services — 210 — 748 Total revenue from Mundipharma Collaboration Agreement $ — $ 3,392 $ — $ 5,922 The following table presents a summary of the activity in the Company's contract liabilities (recorded as deferred revenue on the balance sheet) during the six months ended June 30, 2020 (in thousands): Opening balance, December 31, 2019 $ 9,803 Payments received in advance 7,315 Revenue from performance obligations satisfied during reporting period (5,922 ) Closing balance, June 30, 2020 $ 11,196

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Tables)	6 Months Ended
	Jun. 30, 2020
Commitments and Contingencies Disclosure [Abstract]
Schedule of Amount, Timing and Uncertainty of Cash Flows from Operating Lease	The following table presents information about the amount, timing and uncertainty of cash flows arising from the Company's operating lease as of June 30, 2020 (in thousands): 2020 $ 484 2021 998 Total undiscounted operating lease payments $ 1,482 Less: Imputed interest (120 ) Present value of lease payments $ 1,362
Supplemental Balance Sheet Information	The balance sheet classification of the Company's operating lease is as follows (in thousands): Balance Sheet Classification: Operating lease right-of-use asset $ 1,257 Current lease liability $ 878 Lease liability 484 Total operating lease liability $ 1,362

THE COMPANY AND BASIS OF PRES_2

THE COMPANY AND BASIS OF PRESENTATION (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2020USD ($)segment	Dec. 31, 2019USD ($)	Jun. 30, 2019USD ($)	Dec. 31, 2018USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accumulated deficit	$ 295,434	$ 259,827
Cash, cash equivalents, and restricted cash at end of period	$ 64,085	$ 60,268	$ 44,573	$ 74,562
Number of operating segments | segment	1

SUMMARY OF SIGNIFICANT ACCOUN_4

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Outstanding Potentially Dilutive Securities Excluded from Calculation of Diluted Net Income (Loss) Per Share (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Mar. 31, 2020	Jun. 30, 2020	Jun. 30, 2019
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Recognition of beneficial conversion feature	$ 0
Anti-dilutive securities excluded from calculation of diluted net loss per share (in shares)		30,147,944	23,860,416
Common stock warrants
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share (in shares)		12,517,328	12,517,328
Series X Convertible Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share (in shares)		10,965,190	5,652,310
Common stock options, RSUs and PRSUs issued and outstanding
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share (in shares)		6,665,426	5,690,778
Additional Paid-In Capital
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Recognition of beneficial conversion feature	$ (2,762)	$ (2,800)

FAIR VALUE MEASUREMENTS - Addit

FAIR VALUE MEASUREMENTS - Additional Information (Details)	May 21, 2018USD ($)closing	Jun. 30, 2020USD ($)	Jun. 30, 2019USD ($)	Jun. 30, 2020USD ($)	Jun. 30, 2019USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent forward purchase obligations	$ 4,300,000
Change in fair value of contingent forward purchase obligations resulting in a loss		$ 0	$ 681,000	$ 0	$ 411,000
Registered Direct Offering
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Aggregate value of shares authorized to be sold	$ 120,000,000
Number of direct offering closings | closing	3

FAIR VALUE MEASUREMENTS - Summa

FAIR VALUE MEASUREMENTS - Summary of Financial Instruments Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Assets:
Cash and money market funds	$ 54,826	$ 50,268
Restricted cash and money market accounts	9,259	10,000
Total assets at fair value	64,085	60,268
LEVEL 1
Assets:
Cash and money market funds	54,826	50,268
Restricted cash and money market accounts	9,259	10,000
Total assets at fair value	64,085	60,268
LEVEL 2
Assets:
Cash and money market funds	0	0
Restricted cash and money market accounts	0	0
Total assets at fair value	0	0
LEVEL 3
Assets:
Cash and money market funds	0	0
Restricted cash and money market accounts	0	0
Total assets at fair value	$ 0	$ 0

DEBT - Additional Information (

DEBT - Additional Information (Details) - USD ($)	Jul. 29, 2019	Jul. 27, 2018	Oct. 03, 2016	Jun. 30, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Shares of common stock issued upon exercise of warrant (in shares)			17,331
Exercise price of warrant (in dollars per share)			$ 11.54
Percentage of principal of debt used to calculate number of shares issued by warrant			2.00%
Period of average closing price used to calculate number of shares issued by warrant			30 days
Warrant term			10 years
Restricted cash				$ 9,259,000	$ 10,000,000
Term Loan | Loan Agreement
Debt Instrument [Line Items]
Term loans, maximum borrowing capacity			$ 20,000,000
Prepayment fee percentage in year one			2.00%
Prepayment fee percentage in year two			1.00%
Variable annual rate		4.50%		4.50%
Milestone satisfaction period (within)	30 days
Term Loan | Loan Agreement | Prime Rate
Debt Instrument [Line Items]
Basis spread on variable rate		0.75%
Term Loan | Term A Loan
Debt Instrument [Line Items]
Borrowed from the lender			$ 10,000,000
Term Loan | Term B Loan
Debt Instrument [Line Items]
Term loans, maximum borrowing capacity			$ 10,000,000

DEBT - Schedule of Future Princ

DEBT - Schedule of Future Principal Payments (Details) - Term A Loan - Term Loan $ in Thousands	Jun. 30, 2020USD ($)
Year ended:
December 31, 2020	$ 2,222
December 31, 2021	4,444
December 31, 2022	2,593
Total future principal payments due under the Term A Loan	$ 9,259

STOCKHOLDERS_ EQUITY - Addition

STOCKHOLDERS’ EQUITY - Additional Information (Details)	Feb. 12, 2020USD ($)$ / sharesshares	Sep. 03, 2019USD ($)day$ / sharesshares	Mar. 22, 2019shares	May 23, 2018USD ($)$ / sharesshares	May 21, 2018USD ($)closingday$ / shares	May 31, 2018$ / sharesshares	Jun. 30, 2020USD ($)$ / sharesshares	Mar. 31, 2020USD ($)	Jun. 30, 2019USD ($)	Jun. 30, 2020USD ($)vote_per_share$ / sharesshares	Jun. 30, 2019USD ($)	Dec. 31, 2019$ / sharesshares	Oct. 03, 2016$ / shares
Class of Stock [Line Items]
Fair value of common stock | $								$ 0
Recognition of beneficial conversion feature | $							$ 0		$ 0	$ 2,762,000	$ 0
Weighted average share price allowing reduction of aggregate offering size (in dollars per share) | $ / shares					$ 6.27
Preferred stock, shares authorized (in shares)							10,000,000			10,000,000		10,000,000
Preferred stock, par value (in dollars per share) | $ / shares							$ 0.0001			$ 0.0001		$ 0.0001
Common stock, shares authorized (in shares)							200,000,000			200,000,000		200,000,000
Number of votes for each share held | vote_per_share										1
Dividends in arrears or default | $										$ 0
Warrants to purchase shares of common stock outstanding (in shares)							33,007,969			33,007,969		24,553,840
Exercise price of warrant (in dollars per share) | $ / shares													$ 11.54
Rights Offering, February 2020
Class of Stock [Line Items]
Net proceeds | $	$ 30,000,000
Offering costs | $	800,000
Proceeds from right offerings | $	$ 29,200,000
Registered Direct Offering
Class of Stock [Line Items]
Aggregate value of shares authorized to be sold | $					$ 120,000,000
Number of direct offering closings | closing					3
Registered direct offering, third closing
Class of Stock [Line Items]
Offering price (in dollars per share) | $ / shares					$ 4.70
Option fee paid by investors relating to third closing | $				$ 500,000
Registered direct offering, second closing
Class of Stock [Line Items]
Offering price (in dollars per share) | $ / shares					$ 4.70
Threshold trading days | day					5
Registered direct offering, first closing and First Private Placement
Class of Stock [Line Items]
Net proceeds | $				$ 49,500,000
Controlled Equity Sales Agreement, Cantor Fitzgerald and Company
Class of Stock [Line Items]
Net proceeds | $										$ 4,700,000
Shares sold (in shares)										1,334,369
Common Stock
Class of Stock [Line Items]
Conversion of stock, shares converted (in shares)			1,200,000
Common Stock | Rights Offering, February 2020
Class of Stock [Line Items]
Shares sold (in shares)	6,639,307
Offering price (in dollars per share) | $ / shares	$ 2.51
Common Stock | Private Placement, Stock Purchase Agreement
Class of Stock [Line Items]
Net proceeds | $		$ 9,000,000
Shares sold (in shares)		4,781,408
Offering price (in dollars per share) | $ / shares		$ 1.884
Premium percentage on volume weighted average price per share		20.00%
Threshold trading days | day		10
Common Stock | Registered direct offering, first closing
Class of Stock [Line Items]
Shares sold (in shares)				6,185,987
Offering price (in dollars per share) | $ / shares				$ 4.70
Series X Convertible Preferred Stock
Class of Stock [Line Items]
Beneficial conversion feature fair value | $				$ 10,300,000
Recognition of beneficial conversion feature | $				$ 10,300,000
Preferred stock, shares authorized (in shares)						5,000,000	5,000,000			5,000,000		5,000,000
Preferred stock, par value (in dollars per share) | $ / shares						$ 0.0001	$ 0.0001			$ 0.0001		$ 0.0001
Preferred stock issued (in shares)							1,096,519			1,096,519		565,231
Preferred stock outstanding (in shares)							1,096,519			1,096,519		565,231
Conversion of stock, shares issued (in shares)			120,000
Common stock issued for each preferred stock (in shares)						10
Maximum ownership following conversion						9.99%
Series X Convertible Preferred Stock | Rights Offering, February 2020
Class of Stock [Line Items]
Shares sold (in shares)	531,288
Offering price (in dollars per share) | $ / shares	$ 25.10
Fair value of common stock | $	$ 2,800,000
Series X Convertible Preferred Stock | Registered direct offering, first closing
Class of Stock [Line Items]
Shares sold (in shares)				445,231
Offering price (in dollars per share) | $ / shares				$ 47
Common stock warrants | First Private Placement
Class of Stock [Line Items]
Shares sold (in shares)				12,499,997
Offering price (in dollars per share) | $ / shares				$ 0.125
Weighted Average
Class of Stock [Line Items]
Exercise price of warrant (in dollars per share) | $ / shares							$ 6.82			$ 6.82		$ 6.82
Common stock warrants
Class of Stock [Line Items]
Warrants to purchase shares of common stock outstanding (in shares)							12,517,328			12,517,328		12,517,328

STOCKHOLDERS_ EQUITY - Schedule

STOCKHOLDERS’ EQUITY - Schedule of Common Stock Reserved for Future Issuance (Details) - shares	Jun. 30, 2020	Dec. 31, 2019
Class of Stock [Line Items]
Total (in shares)	33,007,969	24,553,840
Common stock warrants
Class of Stock [Line Items]
Total (in shares)	12,517,328	12,517,328
Series X Convertible Preferred Stock
Class of Stock [Line Items]
Total (in shares)	10,965,190	5,652,310
Common stock options, RSUs and PRSUs issued and outstanding
Class of Stock [Line Items]
Total (in shares)	6,665,426	5,360,563
Authorized for future stock awards under the Company's option plans
Class of Stock [Line Items]
Total (in shares)	2,190,815	559,898
Authorized for future issuance under the ESPP
Class of Stock [Line Items]
Total (in shares)	669,210	463,741

EQUITY INCENTIVE PLANS - Addit

EQUITY INCENTIVE PLANS - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended
	Mar. 31, 2015	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense		$ 995	$ 1,257	$ 2,241	$ 2,541
Weighted-average grant date fair value of employee stock options granted (in dollars per share)				$ 1.47
Total unrecognized share-based compensation expense related to unvested stock options		$ 4,900		$ 4,900
Weighted-average period to recognize unrecognized compensation cost				1 year 8 months 16 days
ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Automatic annual increase in shares authorized for issuance in equity incentive plan	1.00%
Price of stock option as percentage of estimated fair value of shares on date of grant	85.00%
Limit on employee's payroll deductions as a percentage of eligible compensation	15.00%
Issued pursuant to the ESPP (in shares)		132,915		132,915
Estimated unrecognized share-based compensation expense		$ 200		$ 200
Weighted-average period to recognize unrecognized compensation cost				6 months
Restricted Stock Units and Performance-based Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense		100	$ 100	$ 200	$ 100
Estimated unrecognized share-based compensation expense		$ 1,200		$ 1,200
Maximum | ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Automatic increase in number of shares available for issuance (in shares)	490,336
2015 EIP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Automatic annual increase in shares authorized for issuance in equity incentive plan	4.00%
Term for stock options to be granted	10 years
Price of stock option as percentage of estimated fair value of shares on date of grant	100.00%
Voting power threshold	10.00%
2015 EIP | More than 10% of voting power
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Price of stock option as percentage of estimated fair value of shares on date of grant	110.00%
2015 EIP | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
2015 EIP | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	4 years

EQUITY INCENTIVE PLANS - Summar

EQUITY INCENTIVE PLANS - Summary of Restricted Stock Units and Performance-based Restricted Stock Units Activity (Details) - Restricted Stock Units and Performance-based Restricted Stock Units	6 Months Ended
	Jun. 30, 2020shares
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding, beginning balance (in shares)	383,885
RSUs and PRSUs granted (in shares)	125,975
RSUs and PRSUs vested (in shares)	(72,304)
RSUs and PRSUs canceled (in shares)	(21,880)
Outstanding, ending balance (in shares)	415,676

EQUITY INCENTIVE PLANS - Summ_2

EQUITY INCENTIVE PLANS - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2020	Dec. 31, 2019
Number of Shares
Outstanding, beginning balance (in shares)	4,976,678
Options granted (in shares)	1,579,500
Options exercised (in shares)	(1,834)
Options canceled (in shares)	(304,594)
Outstanding, ending balance (in shares)	6,249,750	4,976,678
Vested and expected to vest (in shares)	6,249,750
Exercisable (in shares)	2,512,826
Weighted Average Exercise Price
Outstanding, beginning balance (in dollars per share)	$ 4.37
Options granted (in dollars per share)	2.13
Options exercised (in dollars per share)	2.61
Options canceled (in dollars per share)	8.15
Outstanding, ending balance (in dollars per share)	3.62	$ 4.37
Vested and expected to vest (in dollars per share)	3.62
Exercisable (in dollars per share)	$ 5.32
Weighted Average Remaining Contractual Life in Years
Outstanding	7 years 6 months 7 days	7 years 3 months 7 days
Vested and expected to vest	7 years 6 months 7 days
Exercisable	6 years 6 months 26 days
Total Aggregate Intrinsic Value (in thousands)
Outstanding	$ 5,890	$ 3,880
Vested and expected to vest	5,890
Exercisable	$ 1,222

EQUITY INCENTIVE PLANS - Schedu

EQUITY INCENTIVE PLANS - Schedule of Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total	$ 995	$ 1,257	$ 2,241	$ 2,541
Research and development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total	528	654	1,129	1,297
General and administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total	$ 467	$ 603	$ 1,112	$ 1,244

SIGNIFICANT AGREEMENTS AND CO_3

SIGNIFICANT AGREEMENTS AND CONTRACTS (Details) - USD ($)	Sep. 03, 2019	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Sep. 30, 2019
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue from collaborative agreement		$ 3,392,000	$ 0	$ 5,922,000	$ 0
Mundipharma Medical Company
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Cost sharing percentage	50.00%
Affiliated Entity | Mundipharma Medical Company
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaborative agreement, maximum cost share	$ 31,200,000
Collaborative agreement, potential transaction value	568,000,000
Payments related to collaborative agreement	30,000,000
Revenue recognized from collaborative agreement related to performance obligation satisfied at a point in time		$ 0		0
Affiliated Entity | Mundipharma Medical Company | License of Intellectual Property
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue recognized from collaborative agreement related to performance obligation satisfied at a point in time						$ 17,900,000
Affiliated Entity | Mundipharma Medical Company | Royalty
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue from collaborative agreement				$ 0
Affiliated Entity | Near Term Milestone | Mundipharma Medical Company
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaborative arrangement, additional third party funding commitment	$ 11,100,000

SIGNIFICANT AGREEMENTS AND CO_4

SIGNIFICANT AGREEMENTS AND CONTRACTS - Summary of Contract Liability Activity (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2020USD ($)
Revenue From Collaborative Arrangement, Excluding Revenue From Contract With Customer, Liability [Roll Forward]
Opening balance, December 31, 2019	$ 9,803
Closing balance, June 30, 2020	11,196
Affiliated Entity | Mundipharma Medical Company
Revenue From Collaborative Arrangement, Excluding Revenue From Contract With Customer, Liability [Roll Forward]
Opening balance, December 31, 2019	9,803
Payments received in advance	7,315
Revenue from performance obligations satisfied during reporting period	(5,922)
Closing balance, June 30, 2020	$ 11,196

SIGNIFICANT AGREEMENTS AND CO_5

SIGNIFICANT AGREEMENTS AND CONTRACTS - Revenues Disaggregated by Timing of Revenue Recognition (Details) - Affiliated Entity - Mundipharma Medical Company - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2020	Sep. 30, 2019
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue from Mundipharma Collaboration Agreement, Point in Time	$ 0	$ 0
Revenue from Mundipharma Collaboration Agreement, Over Time	3,392	5,922
License of Intellectual Property
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue from Mundipharma Collaboration Agreement, Point in Time			$ 17,900
Research and Development Services
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue from Mundipharma Collaboration Agreement, Point in Time	0	0
Revenue from Mundipharma Collaboration Agreement, Over Time	3,182	5,174
Clinical Supply Services
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Revenue from Mundipharma Collaboration Agreement, Point in Time	0	0
Revenue from Mundipharma Collaboration Agreement, Over Time	$ 210	$ 748

COMMITMENTS AND CONTINGENCIES -

COMMITMENTS AND CONTINGENCIES - Amount, Timing and Uncertainty of Cash Flows from Operating Lease (Details) $ in Thousands	Jun. 30, 2020USD ($)
Commitments and Contingencies Disclosure [Abstract]
2020	$ 484
2021	998
Total undiscounted operating lease payments	1,482
Less: Imputed interest	(120)
Present value of lease payments	$ 1,362

COMMITMENTS AND CONTINGENCIES_2

COMMITMENTS AND CONTINGENCIES - Supplemental Balance Sheet Information (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Operating lease right-of-use asset	$ 1,257	$ 1,632
Current lease liability	878	818
Lease liability	484	$ 942
Total operating lease liability	$ 1,362

COMMITMENTS AND CONTINGENCIES_3

COMMITMENTS AND CONTINGENCIES - Additional Information (Details) $ in Millions	6 Months Ended
	Jun. 30, 2020USD ($)
Commitments and Contingencies Disclosure [Abstract]
Weighted average remaining lease term	1 year 6 months
Lease payments	$ 0.5
Lease cost	$ 0.5
Variable lease and short-term lease term included within operating lease cost (greater than)	30 days