Cidara Therapeutics (CDTX) 10-Q 9 May 19 2019 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2019	Apr. 30, 2019
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
Entity Registrant Name	Cidara Therapeutics, Inc.
Entity Central Index Key	0001610618
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Emerging Growth Company	true
Entity Small Business	true
Entity Ex Transition Period	false
Entity Common Stock, Shares Outstanding (in shares)		26,641,851

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 57,407	$ 74,562
Prepaid expenses and other current assets	2,869	2,567
Total current assets	60,276	77,129
Property and equipment, net	635	712
Operating lease right-of-use asset	2,131
Other assets	1,271	1,271
Total assets	64,313	79,112
Current liabilities:
Accounts payable	1,713	2,846
Accrued liabilities	3,786	3,883
Accrued compensation and benefits	2,049	2,824
Current portion of lease liability	730
Contingent forward purchase obligations	681	411
Current portion of term loan	9,938	9,928
Total current liabilities	18,897	19,892
Lease liability	1,554
Other long-term liabilities	0	81
Total liabilities	20,451	19,973
Commitments and contingencies
Stockholders' equity:
Preferred stock	0	0
Common stock, $0.0001 par value; 200,000,000 shares authorized at March 31, 2019 and December 31, 2018; 26,641,851 and 27,816,014 shares issued and outstanding at March 31, 2019 and December 31, 2018, respectively	3	3
Additional paid-in capital	279,155	277,871
Accumulated deficit	(235,296)	(218,735)
Total stockholders' equity	43,862	59,139
Total liabilities and stockholders' equity	64,313	79,112
Series X Convertible Preferred Stock
Stockholders' equity:
Preferred stock	0	0
Total stockholders' equity	$ 0	$ 0

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss (unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Operating expenses:
Research and development	$ 12,669	$ 13,199
General and administrative	3,735	3,611
Total operating expenses	16,404	16,810
Loss from operations	(16,404)	(16,810)
Other income (expense):
Change in fair value of contingent forward purchase obligations	(270)	0
Interest income, net	113	61
Total other income (expense)	(157)	61
Net loss attributable to common shareholders	$ (16,561)	$ (16,749)
Basic and diluted net loss per share (in dollars per share)	$ (0.60)	$ (0.80)
Shares used to compute basic and diluted net loss per share (in shares)	27,729,977	20,894,353
Net loss	$ (16,561)	$ (16,749)
Unrealized loss on short-term investments	0	(10)
Comprehensive loss	$ (16,561)	$ (16,759)

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2019	Dec. 31, 2018
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)	26,641,851	27,816,014
Common stock, shares outstanding (in shares)	26,641,851	27,816,014
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)	565,231	445,231
Preferred stock, shares outstanding (in shares)	565,231	445,231

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement of Cash Flows [Abstract]
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	$ 2,295
Operating activities:
Net loss	(16,561)	$ (16,749)
Adjustments to reconcile net loss to net cash used in operating activities:
Operating lease right-of-use assets and liabilities, net	72
Depreciation and amortization	86	139
Stock-based compensation	1,284	1,461
Non-cash interest expense	7	15
Amortization of discount or premium on short-term investments	0	36
Amortization of debt issue costs	2	5
Deferred rent	0	(10)
Change in fair value of contingent forward purchase obligations	270	0
Changes in assets and liabilities:
Prepaid expenses and other current assets	(301)	482
Accounts payable and accrued liabilities	(1,231)	549
Accrued compensation	(774)	(650)
Net cash used in operating activities	(17,146)	(14,722)
Investing activities:
Purchases of short-term investments	0	(5,803)
Maturities of short-term investments	0	6,285
Purchases of property and equipment	(9)	(31)
Net cash provided by investing activities	(9)	451
Financing activities:
Proceeds from issuance of common stock, net of issuance costs	0	6,440
Proceeds from exercise of stock options	0	28
Net cash provided by financing activities	0	6,468
Net decrease in cash, cash equivalents, and restricted cash	(17,155)	(7,803)
Cash, cash equivalents, and restricted cash at beginning of period	74,562	60,813
Cash, cash equivalents, and restricted cash at end of period	57,407	53,010
Supplemental disclosure of cash flows:
Interest paid	155	137
Non-cash investing and financing activities:
Vesting of early exercised stock options	0	9
Deferred financing costs incurred but not yet paid	$ 0	$ 133

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Series X Convertible Preferred Stock	Common Stock	Additional Paid-In Capital	Accumulated Deficit	Other Comprehensive Loss
Balance, beginning (in shares) at Dec. 31, 2017		0	20,525,688
Balance, beginning at Dec. 31, 2017	$ 59,744	$ 0	$ 2	$ 209,140	$ (149,390)	$ (8)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of stock (in shares)			847,937
Issuance of stock	6,435			6,435
Vesting of restricted shares/ restricted stock units (in shares)			3,964
Vesting of restricted shares/ restricted stock units	9			9
Issuance of common stock for exercise of stock options (in shares)			12,147
Issuance of common stock for exercise of stock options	28			28
Stock-based compensation	1,461			1,461
Unrealized loss on marketable securities	(10)					(10)
Net loss	(16,749)				(16,749)
Balance, ending (in shares) at Mar. 31, 2018		0	21,389,736
Balance, ending at Mar. 31, 2018	50,918	$ 0	$ 2	217,073	(166,139)	(18)
Balance, beginning (in shares) at Dec. 31, 2018		445,231,000	27,816,014,000
Balance, beginning at Dec. 31, 2018	59,139	$ 0	$ 3	277,871	(218,735)	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Vesting of restricted shares/ restricted stock units (in shares)			25,837,000
Issuance of Series X preferred stock in exchange for common stock (in shares)		120,000,000	1,200,000,000
Issuance of Series X preferred stock in exchange for common stock	$ 0
Issuance of common stock for exercise of stock options (in shares)	0
Stock-based compensation	$ 1,284			1,284
Unrealized loss on marketable securities	0
Net loss	(16,561)				(16,561)
Balance, ending (in shares) at Mar. 31, 2019		565,231,000	26,641,851,000
Balance, ending at Mar. 31, 2019	$ 43,862	$ 0	$ 3	$ 279,155	$ (235,296)	$ 0

THE COMPANY AND BASIS OF PRESEN

THE COMPANY AND BASIS OF PRESENTATION	3 Months Ended
	Mar. 31, 2019
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. The Company’s portfolio is comprised of a proprietary product candidate for the treatment and prevention of serious fungal infections. The Company is also conducting research in bacterial and viral infection. 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 March 31, 2019 , the Company had an accumulated deficit of $235.3 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 March 31, 2019 , the Company had cash and cash equivalents of $57.4 million . Based on the Company’s current business plan, management believes that existing cash and cash equivalents will be sufficient to fund the Company’s obligations through the third quarter of 2019. The Company’s ability to execute its operating plan beyond the third quarter of 2019 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. 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 March 31, 2019 and 2018 . 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. 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 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. 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	3 Months Ended
	Mar. 31, 2019
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. Investments Available-for-Sale Available-for-sale securities are carried at fair value, with the unrealized gains and losses reported in accumulated other comprehensive loss. The amortized cost of debt securities is adjusted for amortization of premiums and accretion of discounts to maturity. The amortization of premiums and accretion of discounts is included in interest income. Realized gains and losses and declines in value judged to be other-than-temporary, if any, on available-for-sale securities are included in other income (expense). The cost of securities sold is based on the specific identification method. Interest and dividends on securities classified as available-for-sale are included in interest income. Securities with maturity dates of 12 months or less from the date of purchase are classified as short-term investments and securities with maturity dates of more than 12 months are classified as long-term investments. Concentration of Credit Risk The Company’s financial instruments that are exposed to concentrations of credit risk consist primarily of cash and cash equivalents and short-term investments. Periodically, 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 revenues when customers obtain control of promised goods or services, in an amount that reflects the consideration which it expects to receive in exchange for those goods or services. The Company recognizes revenues following the five step model prescribed under Accounting Standards Update ("ASU") No. 2014-09 ("ASU 2014-09"): (i) identify 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 revenues when (or as) the Company satisfies the performance obligation. 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. Comprehensive Loss Comprehensive loss is defined as the change in equity during a period from transactions and other events and/or circumstances from non-owner sources. The Company’s only component of other comprehensive loss is unrealized losses on short-term investments. Comprehensive losses have been reflected in the condensed consolidated statements of operations and comprehensive loss for all periods presented. 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 (RSUs) and Performance-based RSUs (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, unvested restricted common stock subject to repurchase, and options, RSUs, and PRSUs 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. 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): March 31, 2019 2018 Common stock warrants 12,517,328 17,331 Common stock options, RSUs and PRSUs issued and outstanding 5,690,390 4,352,640 Series X Convertible Preferred stock 5,652,310 — Common stock subject to repurchase — 5,341 Total 23,860,028 4,375,312 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, contingent forward purchase obligations, and long-term debt. Fair value estimates of these instruments are made at a specific point in time 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, 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 short-term investments is based upon market prices quoted on the last day of the fiscal period or other observable market inputs. 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. Recently Issued Accounting Standards Recently Issued Accounting Standards Not Yet Adopted During 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 updated guidance is effective for interim and annual periods beginning after December 15, 2019, and early adoption is permitted. The Company is currently assessing the impact that this standard will have on its consolidated financial statements. Recently Adopted Accounting Standards In March 2019, the Financial Accounting Standards Board, or FASB, issued Accounting Standards Update No. 2019-01, "Leases (Topic 842): Codification Improvements." In July 2018, the FASB issued Accounting Standards Update No. 2018-11, "Leases (Topic 842): Targeted Improvements" and Accounting Standards Update No. 2018-10, "Codification Improvements to Topic 842, Leases." These updates provide additional clarification, an optional transition method, a practical expedient and implementation guidance on the previously issued Accounting Standards Update No. 2016-02, "Leases (Topic 842)." Collectively, these updates supersede the lease guidance in Accounting Standards Codification, or ASC, Topic 840 and require lessees to recognize for all leases, with the exception of short-term leases, a lease liability, which is a lessee’s obligation to make lease payments arising from a lease, measured on a discounted basis. Concurrently, lessees are required to recognize a right of use asset that represents the lessee’s right to use, or control the use of, a specified asset for the lease term. We adopted this standard on January 1, 2019 by applying the optional transition method on the adoption date and did not adjust comparative periods. We also elected the package of practical expedients permitted, which among other things, allowed us to carry forward the lease classification for our existing leases. The adoption of this standard impacted our 2019 opening consolidated balance sheet as we recorded operating lease liabilities of $2.5 million and right of use assets of $2.3 million , which equals the lease liabilities net of accrued rent. The adoption of this standard did not have an impact on our consolidated statements of income or cash flows. During 2018, the FASB issued ASU 2018-07, "Improvements to Nonemployee Share-Based Payment Accounting," which expanded the scope of Topic 718 to include share-based payment transactions for acquiring goods and services from non-employees. These updates align the guidance for share-based payments to nonemployees with the guidance for share-based payments granted to employees, including the measurement of equity-classified awards, which is fixed at the grant date under the new guidance. The updated guidance is effective for interim and annual periods beginning after December 15, 2018, and early adoption is permitted. The Company adopted ASU 2018-07 effective January 1, 2019. The adoption of this standard did not have a material impact on the Company's financial statements.

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	3 Months Ended
	Mar. 31, 2019
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 loss of $0.3 million were recorded during the three months ended March 31, 2019 . The contingent forward purchase obligation was valued at $0.7 million and $0.4 million as of March 31, 2019 and December 31, 2018 , respectively. 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 March 31, 2019 Assets: Money market funds $ 56,759 $ 56,759 $ — $ — Total assets at fair value $ 56,759 $ 56,759 $ — $ — Liabilities: Contingent forward purchase obligations $ 681 $ — $ — $ 681 Total liabilities at fair value $ 681 $ — $ — $ 681 December 31, 2018 Assets: Money market funds $ 74,077 $ 74,077 $ — $ — Total assets at fair value $ 74,077 $ 74,077 $ — $ — Liabilities: Contingent forward purchase obligations $ 411 $ — $ — $ 411 Total liabilities at fair value $ 411 $ — $ — $ 411

DEBT

DEBT	3 Months Ended
	Mar. 31, 2019
Debt Disclosure [Abstract]
DEBT	DEBT Term Loans — On October 3, 2016, the Company entered into a loan and security agreement, (the "Loan Agreement"), with Pacific Western Bank, as the collateral agent and a lender (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 (the "Term A Loan"). Under the terms of the Loan Agreement, because the Company achieved positive results from the STRIVE Phase 2 clinical trial of rezafungin by March 31, 2018 (the "Milestone"), the Company may have borrowed, at its sole discretion through October 3, 2018, from the Lender up to an additional $10.0 million (the "Term B Loan," and together with the Term A Loan, the "Term Loans"). 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 operating covenant 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 (the "Milestone"). 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 (the "Maturity Date") and the interest rate. The Maturity Date is January 3, 2022. Payments under the Term Loans will be interest-only through July 31, 2019, which will be extended to October 31, 2019 if the Milestone is achieved. 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 March 31, 2019 , the Term Loans bear interest at 6.25% . The Company evaluated the First and Second Amendments to evaluate 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, including the receipt of positive data from Part B of the STRIVE Phase 2 clinical trial of rezafungin on or prior to July 31, 2019, or the occurrence of a material adverse change, the collateral agent will have 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 March 31, 2019 and December 31, 2018 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 March 31, 2019 , future principal payments due under the Term A Loan are as follows (in thousands): Year ended: December 31, 2019 $ 1,667 December 31, 2020 4,000 December 31, 2021 4,000 December 31, 2022 333 Total future principal payments due under the Term A Loan $ 10,000

STOCKHOLDERS_ EQUITY

STOCKHOLDERS’ EQUITY	3 Months Ended
	Mar. 31, 2019
Equity [Abstract]
STOCKHOLDERS’ EQUITY	STOCKHOLDERS’ EQUITY 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 (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. In the second closing of the offering, the Company may sell up to an additional $50.0 million in shares of common stock to investors who purchased at least $1.0 million of shares of common stock in the first closing of the offering at a purchase price per share that is equal to 75% of the volume weighted average price of the common stock for the five trading days following the Company’s public release of topline data from Part B of its STRIVE global, randomized Phase 2 clinical trial of rezafungin, provided that the Company will not be obligated to complete the second closing of the offering if the purchase price is less than $4.70 per share. In the optional third closing, which would be held five trading days following the second closing, purchasers who fully participate in the second closing may, at their option, purchase up to an additional $20.0 million of common stock at a purchase price per share equal to the purchase price of the shares purchased at the second closing. At the Company’s option, and prior to the completion of the second or third closing, as applicable, the Company may reduce the aggregate offering size of the such closing by the dollar amount received by the Company from any (i) strategic partnership or other non-dilutive source of funding or (ii) sale of equity securities at a price greater than $6.81 per share. If the volume weighted average price of the Company's common stock for the five trading days following the Company's public release of topline data from Part B of its STRIVE global, randomized Phase 2 clinical trial of rezafungin is below $6.27 , the resulting purchase price for the second and third closings will be less than $4.70 per share and the Company will be unable to complete the second and third closings without first obtaining the approval of our stockholders. The Company will also offer to each purchaser in the second or third closing the opportunity, in lieu of purchasing common stock, to purchase Series X Convertible Preferred Stock. For each share of Series X Convertible Preferred Stock purchased in the offering in lieu of common stock, the Company will reduce the number of shares of common stock being sold by 10 shares. Each share of Series X Convertible Preferred Stock is convertible into 10 shares of common stock. As the issuance of the additional closings are outside the control of the Company, the second closing and optional third closing are accounted for as a liability in accordance with ASC 480, "Distinguishing Liabilities from Equity," which is measured at fair value on a recurring basis. See Note 3 to our financial statements for additional information. In a private placement to be held concurrently with the optional third closing (the “Second Private Placement”), the Company would sell warrants to purchase up to 2,500,000 shares of Common Stock to the purchasers that participate, at a purchase price of $0.125 per warrant share (such warrants, together with the warrants sold in the First Private Placement, each, a “Warrant”, and collectively, the “Warrants”). The Warrants are exercisable immediately for cash at an exercise price of $6.81 per share. The Warrants issued in the First Private Placement will expire upon the earliest of (i) five years from the date of the first closing of the offering, (ii) the date that the holder of such Warrant transfers or sells any of the shares of Common Stock purchased by such holder in the first closing of the offering, if such transfer or sale occurs prior to the date that is 120 calendar days following the closing of the first closing of the offering, (iii) the taking of any short position on the Common Stock by the holder of such Warrant prior to the completion of the second closing of the offering, and (iv) the failure by the holder of such Warrant to purchase its pro rata allocation of shares of Common Stock in the second closing of the offering. The Company accounts for the Warrants as equity instruments in accordance with ASC 480, "Distinguishing Liabilities from Equity ." The Warrants issued in the Second Private Placement will expire five years from the date of the third closing of the offering. 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 March 31, 2019 . 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 March 31, 2019 , 565,231 shares of Series X Convertible Preferred Stock were issued and outstanding. On March 22, 2019, the Company entered into an Exchange Agreement with Biotechnology Value Fund, L.P., and certain of its affiliated entities (collectively, “BVF”), pursuant to which BVF, 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 should be 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 March 31, 2019 . 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. Common Stock Reserved for Future Issuance Common stock reserved for future issuance is as follows (in common stock equivalent shares): March 31, 2019 December 31, 2018 Common stock warrants 12,517,328 12,517,328 Stock options, RSUs and PRSUs issued and outstanding 5,690,390 4,392,671 Series X Convertible Preferred Stock 5,652,310 4,452,310 Authorized for future issuance under the ESPP 706,242 706,242 Authorized for future stock awards under the Company's option plans 461,457 669,873 Total 25,027,727 22,738,424

STOCK INCENTIVE PLANS

STOCK INCENTIVE PLANS	3 Months Ended
	Mar. 31, 2019
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
STOCK INCENTIVE PLANS	STOCK 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 (“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 ("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. No shares were issued pursuant to the ESPP during the three months ended March 31, 2019 . Restricted Stock Units The following table summarizes RSU and PRSU activity during the three months ended March 31, 2019 : Number of Outstanding at December 31, 2018 260,000 RSUs and PRSUs granted 259,520 RSUs and PRSUs vested (23,337 ) RSUs and PRSUs canceled (325 ) Outstanding at March 31, 2019 495,858 For the three months ended March 31, 2019 , stock-based compensation expense related to RSUs and PRSUs was approximately $58,000 . At March 31, 2019 , estimated unrecognized compensation expense related to RSUs and PRSUs grants was approximately $2.2 million . Stock Options The following table summarizes stock option activity during the three months ended March 31, 2019 : Number of Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Life in Years Total Aggregate Intrinsic Value (in thousands) Outstanding at December 31, 2018 4,132,671 $ 6.58 7.41 $ 25 Options granted 1,067,150 2.61 Options exercised — — Options canceled (5,289 ) 6.93 Outstanding at March 31, 2019 5,194,532 $ 5.76 7.70 $ 191 Vested and expected to vest at March 31, 2019 5,194,532 $ 5.76 7.70 $ 191 Exercisable at March 31, 2019 2,656,448 $ 7.27 6.49 $ 148 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 2019 2018 Research and development $ 643 $ 640 General and administrative 641 821 Total $ 1,284 $ 1,461 The weighted-average grant date fair value of stock options granted by the Company during the three months ended March 31, 2019 was $1.82 per share. The total grant date fair value of employee stock options that vested during the three months ended March 31, 2019 was $0.9 million . As of March 31, 2019 , total unrecognized share-based compensation expense related to unvested employee stock options of the Company was approximately $6.4 million . This unrecognized compensation cost is expected to be recognized over a weighted-average period of approximately 2.4 years . As of March 31, 2019 , total unrecognized compensation expense related to the ESPP was approximately $0.6 million . This unrecognized compensation cost is expected to be recognized over approximately 0.6 years . Common Stock Warrants As of March 31, 2019 and December 31, 2018 , warrants to purchase 12,517,328 shares of common stock were outstanding at a weighted average exercise price of $6.82 per share. The intrinsic value of a common stock warrant is the difference between the market price of the common stock at the measurement date and the exercise price of the warrant.

SIGNIFICANT AGREEMENTS AND CONT

SIGNIFICANT AGREEMENTS AND CONTRACTS	3 Months Ended
	Mar. 31, 2019
Deferred Revenue Disclosure [Abstract]
SIGNIFICANT AGREEMENTS AND CONTRACTS	SIGNIFICANT AGREEMENTS AND CONTRACTS Combating Antibiotic Resistant Bacteria Accelerator (CARB-X) Subaward Agreement On March 30, 2017, the Company entered into a Cost Reimbursement Research Subaward Agreement (the "Subaward Agreement") with the Trustees of Boston University. Under the Subaward Agreement, the Company is a subawardee under the CARB-X program. CARB-X is a public-private partnership focused on antibacterials, created by the U.S. Department of Health and Human Services (HHS), Biomedical Advanced Research and Development Authority (BARDA), the NIAID. CARB-X is funded by BARDA and the London-based Wellcome Trust, a global charitable foundation (Wellcome), and administered by the Boston University School of Law. The subaward was intended to support development of the Company's CD201 product candidate. Under the Subaward Agreement, during an initial phase that began on April 1, 2017 and ends upon acceptance by the U.S. Food and Drug Administration of an initial new drug application, CARB-X would reimburse up to $3.9 million of qualifying development expenses. If all of the milestones in such initial phase are met, the CARB-X Joint Oversight Committee will evaluate the progress made in such initial phase and determine whether to exercise its option to fund a second stage. During the second stage, CARB-X would reimburse up to $3.0 million of qualifying development expenses through a Phase 1 clinical trial. Such second stage would be subject to a new subaward agreement. The Subaward Agreement can be terminated upon the delivery of 30 days written notice to the Company for default or convenience. Upon receipt of a notice of termination, the Company must discontinue contract activities and CARB-X must pay the Company a final settlement based on eligible expenses incurred under the Subaward Agreement. Based on preclinical studies of CD201 as well as preclinical studies of antibody-drug conjugates (ADCs) from the Cloudbreak program, the Company decided in February 2018 to cease development of CD201 to focus on the more promising ADCs for the same indication. Based on the decision to focus efforts on the ADCs, the Company will no longer be seeking funding under the Subaward Agreement relating to CD201.

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	3 Months Ended
	Mar. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES Litigation From time to time, the Company may be involved in various lawsuits, legal proceedings, or claims that arise in the ordinary course of business. Management believes there are no claims or actions pending against the Company as of March 31, 2019 which will have, individually or in the aggregate, a material adverse effect on its business, liquidity, financial position, or results of operations. Litigation, however, is subject to inherent uncertainties, and an adverse result in such matters may arise from time to time that may harm the Company’s business. Lease Obligations The Company adopted ASU 2016-02, "Leases," on January 1, 2019, which resulted in the recognition of operating leases on the balance sheet. See Note 2 for more information on the adoption of the ASU. The Company determines if a contract contains a lease at inception and recognizes operating lease right-of-use assets and operating lease liabilities based on the present value of the future minimum lease payments at the commencement date. As the Company's leases do not provide an implicit rate, management develops incremental borrowing rates based on the information available at the commencement date in determining the present value of future payments. Lease agreements that have lease and non-lease components are accounted for as a single lease component. Lease expense is recognized on a straight-line basis over the lease term. The Company's single lease upon adoption is for laboratory and office space in San Diego, California and was entered into in June 2015. Amendments for additional space were entered into in February 2015, March 2015, and August 2015. On June 29, 2018 the Company entered into a Fourth Amendment to its lease which extended the term of the lease by an additional 36 months and increased base rent to $70,000 per month effective January 1, 2019. The Company has also been granted an option, exercisable prior to September 30, 2019, to expand its leased premises on the same terms as the current lease, subject to compliance with specified conditions. The lease expires in December 2021 with options for two individual two -year extensions. The lease is subject to charges for common area maintenance and other costs, and base rent is subject to 3% annual increases every January. The adjusted incremental borrowing rate used in measuring the Company's lease liability was 10.8% . The following table presents information about the amount, timing and uncertainty of cash flows arising from the Company's operating lease as of March 31, 2019 (in thousands): 2019 $ 701 2020 963 2021 992 Total undiscounted operating lease payments $ 2,656 Less: Imputed interest 372 Present value of lease payments $ 2,284 The balance sheet classification of the Company's operating lease is as follows (in thousands): Balance Sheet Classification: Operating lease right-of-use asset $ 2,131 Current lease liability $ 730 Lease liability 1,554 Total operating lease liability $ 2,284 As of March 31, 2019 , the weighted average remaining lease term was 2.8 years . Cash paid for amounts included in the present value of operating lease liabilities was $233,000 for the three months ended March 31, 2019 . Operating lease costs were $301,000 for the three months ended March 31, 2019 . 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 within 30 days of notice.

SUMMARY OF SIGNIFICANT ACCOUN_2

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	3 Months Ended
	Mar. 31, 2019
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 March 31, 2019 , the Company had an accumulated deficit of $235.3 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.
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 March 31, 2019 and 2018 .
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.
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 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.
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.
Investments Available-for-Sale	Investments Available-for-Sale Available-for-sale securities are carried at fair value, with the unrealized gains and losses reported in accumulated other comprehensive loss. The amortized cost of debt securities is adjusted for amortization of premiums and accretion of discounts to maturity. The amortization of premiums and accretion of discounts is included in interest income. Realized gains and losses and declines in value judged to be other-than-temporary, if any, on available-for-sale securities are included in other income (expense). The cost of securities sold is based on the specific identification method. Interest and dividends on securities classified as available-for-sale are included in interest income. Securities with maturity dates of 12 months or less from the date of purchase are classified as short-term investments and securities with maturity dates of more than 12 months are classified as long-term investments.
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 and short-term investments. Periodically, 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 revenues when customers obtain control of promised goods or services, in an amount that reflects the consideration which it expects to receive in exchange for those goods or services. The Company recognizes revenues following the five step model prescribed under Accounting Standards Update ("ASU") No. 2014-09 ("ASU 2014-09"): (i) identify 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 revenues when (or as) the Company satisfies the performance obligation.
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.
Comprehensive Loss	Comprehensive Loss Comprehensive loss is defined as the change in equity during a period from transactions and other events and/or circumstances from non-owner sources. The Company’s only component of other comprehensive loss is unrealized losses on short-term investments. Comprehensive losses have been reflected in the condensed consolidated statements of operations and comprehensive loss for all periods presented.
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 (RSUs) and Performance-based RSUs (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, unvested restricted common stock subject to repurchase, and options, RSUs, and PRSUs 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, contingent forward purchase obligations, and long-term debt. Fair value estimates of these instruments are made at a specific point in time 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, 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 short-term investments is based upon market prices quoted on the last day of the fiscal period or other observable market inputs. 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.
Recently Issued Accounting Standards	Recently Issued Accounting Standards Recently Issued Accounting Standards Not Yet Adopted During 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 updated guidance is effective for interim and annual periods beginning after December 15, 2019, and early adoption is permitted. The Company is currently assessing the impact that this standard will have on its consolidated financial statements. Recently Adopted Accounting Standards In March 2019, the Financial Accounting Standards Board, or FASB, issued Accounting Standards Update No. 2019-01, "Leases (Topic 842): Codification Improvements." In July 2018, the FASB issued Accounting Standards Update No. 2018-11, "Leases (Topic 842): Targeted Improvements" and Accounting Standards Update No. 2018-10, "Codification Improvements to Topic 842, Leases." These updates provide additional clarification, an optional transition method, a practical expedient and implementation guidance on the previously issued Accounting Standards Update No. 2016-02, "Leases (Topic 842)." Collectively, these updates supersede the lease guidance in Accounting Standards Codification, or ASC, Topic 840 and require lessees to recognize for all leases, with the exception of short-term leases, a lease liability, which is a lessee’s obligation to make lease payments arising from a lease, measured on a discounted basis. Concurrently, lessees are required to recognize a right of use asset that represents the lessee’s right to use, or control the use of, a specified asset for the lease term. We adopted this standard on January 1, 2019 by applying the optional transition method on the adoption date and did not adjust comparative periods. We also elected the package of practical expedients permitted, which among other things, allowed us to carry forward the lease classification for our existing leases. The adoption of this standard impacted our 2019 opening consolidated balance sheet as we recorded operating lease liabilities of $2.5 million and right of use assets of $2.3 million , which equals the lease liabilities net of accrued rent. The adoption of this standard did not have an impact on our consolidated statements of income or cash flows. During 2018, the FASB issued ASU 2018-07, "Improvements to Nonemployee Share-Based Payment Accounting," which expanded the scope of Topic 718 to include share-based payment transactions for acquiring goods and services from non-employees. These updates align the guidance for share-based payments to nonemployees with the guidance for share-based payments granted to employees, including the measurement of equity-classified awards, which is fixed at the grant date under the new guidance. The updated guidance is effective for interim and annual periods beginning after December 15, 2018, and early adoption is permitted. The Company adopted ASU 2018-07 effective January 1, 2019. The adoption of this standard did not have a material impact on the Company's financial statements.

SUMMARY OF SIGNIFICANT ACCOUN_3

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)	3 Months Ended
	Mar. 31, 2019
Accounting Policies [Abstract]
Summary of Outstanding Potentially Dilutive Securities Excluded from Calculation of Diluted Net 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): March 31, 2019 2018 Common stock warrants 12,517,328 17,331 Common stock options, RSUs and PRSUs issued and outstanding 5,690,390 4,352,640 Series X Convertible Preferred stock 5,652,310 — Common stock subject to repurchase — 5,341 Total 23,860,028 4,375,312

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	3 Months Ended
	Mar. 31, 2019
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 March 31, 2019 Assets: Money market funds $ 56,759 $ 56,759 $ — $ — Total assets at fair value $ 56,759 $ 56,759 $ — $ — Liabilities: Contingent forward purchase obligations $ 681 $ — $ — $ 681 Total liabilities at fair value $ 681 $ — $ — $ 681 December 31, 2018 Assets: Money market funds $ 74,077 $ 74,077 $ — $ — Total assets at fair value $ 74,077 $ 74,077 $ — $ — Liabilities: Contingent forward purchase obligations $ 411 $ — $ — $ 411 Total liabilities at fair value $ 411 $ — $ — $ 411

DEBT (Tables)

DEBT (Tables)	3 Months Ended
	Mar. 31, 2019
Debt Disclosure [Abstract]
Schedule of Future Principal Payments	As of March 31, 2019 , future principal payments due under the Term A Loan are as follows (in thousands): Year ended: December 31, 2019 $ 1,667 December 31, 2020 4,000 December 31, 2021 4,000 December 31, 2022 333 Total future principal payments due under the Term A Loan $ 10,000

STOCKHOLDERS_ EQUITY (Tables)

STOCKHOLDERS’ EQUITY (Tables)	3 Months Ended
	Mar. 31, 2019
Equity [Abstract]
Schedule of Common Stock Reserved for Future Issuance	Common stock reserved for future issuance is as follows (in common stock equivalent shares): March 31, 2019 December 31, 2018 Common stock warrants 12,517,328 12,517,328 Stock options, RSUs and PRSUs issued and outstanding 5,690,390 4,392,671 Series X Convertible Preferred Stock 5,652,310 4,452,310 Authorized for future issuance under the ESPP 706,242 706,242 Authorized for future stock awards under the Company's option plans 461,457 669,873 Total 25,027,727 22,738,424

STOCK INCENTIVE PLANS (Tables)

STOCK INCENTIVE PLANS (Tables)	3 Months Ended
	Mar. 31, 2019
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary of RSU and PRSU activity	The following table summarizes RSU and PRSU activity during the three months ended March 31, 2019 : Number of Outstanding at December 31, 2018 260,000 RSUs and PRSUs granted 259,520 RSUs and PRSUs vested (23,337 ) RSUs and PRSUs canceled (325 ) Outstanding at March 31, 2019 495,858
Summary of Stock Option Activity	The following table summarizes stock option activity during the three months ended March 31, 2019 : Number of Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Life in Years Total Aggregate Intrinsic Value (in thousands) Outstanding at December 31, 2018 4,132,671 $ 6.58 7.41 $ 25 Options granted 1,067,150 2.61 Options exercised — — Options canceled (5,289 ) 6.93 Outstanding at March 31, 2019 5,194,532 $ 5.76 7.70 $ 191 Vested and expected to vest at March 31, 2019 5,194,532 $ 5.76 7.70 $ 191 Exercisable at March 31, 2019 2,656,448 $ 7.27 6.49 $ 148
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 2019 2018 Research and development $ 643 $ 640 General and administrative 641 821 Total $ 1,284 $ 1,461

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Tables)	3 Months Ended
	Mar. 31, 2019
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 March 31, 2019 (in thousands): 2019 $ 701 2020 963 2021 992 Total undiscounted operating lease payments $ 2,656 Less: Imputed interest 372 Present value of lease payments $ 2,284
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 $ 2,131 Current lease liability $ 730 Lease liability 1,554 Total operating lease liability $ 2,284

THE COMPANY AND BASIS OF PRES_2

THE COMPANY AND BASIS OF PRESENTATION (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)segment	Dec. 31, 2018USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accumulated deficit	$ 235,296	$ 218,735
Cash and cash equivalents	$ 57,407	$ 74,562
Number of operating segments | segment	1

SUMMARY OF SIGNIFICANT ACCOUN_4

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Net Loss Per Share (Details) - shares	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
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)	23,860,028	4,375,312
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	17,331
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)	5,690,390	4,352,640
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)	5,652,310	0
Common stock subject to repurchase
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)	0	5,341

SUMMARY OF SIGNIFICANT ACCOUN_5

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Jan. 01, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Present value of lease payments	$ 2,284
Operating lease right-of-use asset	$ 2,131
Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Present value of lease payments		$ 2,500
Operating lease right-of-use asset		$ 2,300

FAIR VALUE MEASUREMENTS - Addit

FAIR VALUE MEASUREMENTS - Additional Information (Details)	May 21, 2018USD ($)closing	Mar. 31, 2019USD ($)	Mar. 31, 2018USD ($)	Dec. 31, 2018USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent forward purchase obligations	$ 4,300,000	$ 681,000		$ 411,000
Change in fair value of contingent forward purchase obligations resulting in a gain		$ 270,000	$ 0
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	Mar. 31, 2019	Dec. 31, 2018	May 21, 2018
Assets:
Money market funds	$ 56,759	$ 74,077
Total assets at fair value	56,759	74,077
Liabilities:
Contingent forward purchase obligations	681	411	$ 4,300
Total liabilities at fair value	681	411
LEVEL 1
Assets:
Money market funds	56,759	74,077
Total assets at fair value	56,759	74,077
Liabilities:
Contingent forward purchase obligations	0	0
Total liabilities at fair value	0	0
LEVEL 2
Assets:
Money market funds	0	0
Total assets at fair value	0	0
Liabilities:
Contingent forward purchase obligations	0	0
Total liabilities at fair value	0	0
LEVEL 3
Assets:
Money market funds	0	0
Total assets at fair value	0	0
Liabilities:
Contingent forward purchase obligations	681	411
Total liabilities at fair value	$ 681	$ 411

DEBT - Additional Information (

DEBT - Additional Information (Details) - USD ($)	Jul. 27, 2018	Oct. 03, 2016	Mar. 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
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%		6.25%
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	Mar. 31, 2019USD ($)
Year ended:
December 31, 2019	$ 1,667
December 31, 2020	4,000
December 31, 2021	4,000
December 31, 2022	333
Total future principal payments due under the Term A Loan	$ 10,000

STOCKHOLDERS_ EQUITY - Narrativ

STOCKHOLDERS’ EQUITY - Narrative (Details)	Mar. 22, 2019shares	May 23, 2018USD ($)$ / sharesshares	May 21, 2018USD ($)closingday$ / sharesshares	May 31, 2018$ / sharesshares	Mar. 31, 2019USD ($)vote_per_share$ / sharesshares	Dec. 31, 2018$ / sharesshares	Oct. 03, 2016$ / shares
Class of Stock [Line Items]
Recognition of beneficial conversion feature | $		$ 10,300,000
Share price allowing the reduction of the aggregate offering size (in dollars per share) | $ / shares			$ 6.81
Weighted average share price allowing reduction of aggregate offering size (in dollars per share) | $ / shares			$ 6.27
Number of common shares reduced by each preferred share sold (in shares)			10
Exercise price of warrant (in dollars per share) | $ / shares							$ 11.54
Term of warrants following closing of first closing of the offering			120 days
Preferred stock, shares authorized (in shares)					10,000,000	10,000,000
Preferred stock, par value (in dollars per share) | $ / shares					$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)					200,000,000	200,000,000
Number of votes for each share held | vote_per_share					1
Dividends in arrears or default | $					$ 0
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, first closing
Class of Stock [Line Items]
Shares sold (in shares)		6,185,987
Offering price (in dollars per share) | $ / shares		$ 4.70
Registered direct offering, third closing
Class of Stock [Line Items]
Aggregate value of shares authorized to be sold | $			$ 20,000,000
Offering price (in dollars per share) | $ / shares			$ 4.70
Option fee paid by investors relating to third closing | $		$ 500,000
Threshold trading days | day			5
Registered direct offering, second closing
Class of Stock [Line Items]
Aggregate value of shares authorized to be sold | $			$ 50,000,000
Offering price (in dollars per share) | $ / shares			$ 4.70
Minimum value of shares purchased in order to participate in second closing | $			$ 1,000,000
Percent of the price per share of the volume weighted average price of common stock for the five trading days following the Company's public release of data			75.00%
Threshold trading days | day			5
Registered direct offering, first closing and First Private Placement
Class of Stock [Line Items]
Net proceeds | $		49,500,000
Second Private Placement
Class of Stock [Line Items]
Shares sold (in shares)			2,500,000
Offering price (in dollars per share) | $ / shares			$ 0.125
Series X Convertible Preferred Stock
Class of Stock [Line Items]
Beneficial conversion feature fair value | $		$ 10,300,000
Common stock issued for each preferred stock (in shares)			10	10
Preferred stock, shares authorized (in shares)				5,000,000	5,000,000	5,000,000
Preferred stock, par value (in dollars per share) | $ / shares				$ 0.0001	$ 0.0001	$ 0.0001
Preferred stock issued (in shares)					565,231	445,231
Conversion of stock, shares issued (in shares)	120,000
Preferred stock outstanding (in shares)					565,231	445,231
Maximum ownership following conversion				9.99%
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
Class of Stock [Line Items]
Conversion of stock, shares converted (in shares)	1,200,000
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
Exercise price of warrant (in dollars per share) | $ / shares			$ 6.81
Term of warrant			5 years
Common stock warrants | Second Private Placement
Class of Stock [Line Items]
Term of warrant			5 years

STOCKHOLDERS_ EQUITY - Schedule

STOCKHOLDERS’ EQUITY - Schedule of Common Stock Reserved for Future Issuance (Details) - shares	Mar. 31, 2019	Dec. 31, 2018
Class of Stock [Line Items]
Total (in shares)	25,027,727	22,738,424
Common stock warrants
Class of Stock [Line Items]
Total (in shares)	12,517,328	12,517,328
Stock options, RSUs and PRSUs issued and outstanding
Class of Stock [Line Items]
Total (in shares)	5,690,390	4,392,671
Series X Convertible Preferred Stock
Class of Stock [Line Items]
Total (in shares)	5,652,310	4,452,310
Authorized for future issuance under the ESPP
Class of Stock [Line Items]
Total (in shares)	706,242	706,242
Authorized for future stock awards under the Company's option plans
Class of Stock [Line Items]
Total (in shares)	461,457	669,873

STOCK INCENTIVE PLANS - Additi

STOCK INCENTIVE PLANS - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average grant date fair value of employee stock options granted (in dollars per share)		$ 1.82
Grant date fair value of employee stock options vested		$ 0.9
Total unrecognized share-based compensation expense related to unvested employee stock options		$ 6.4
Period to recognize unrecognized compensation cost		2 years 4 months 24 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)		0
Estimated unrecognized share-based compensation expense		$ 0.6
Period to recognize unrecognized compensation cost		7 months 10 days
Common stock warrants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock warrants outstanding (in shares)		12,517,328	12,517,328
Common stock warrants outstanding, weighted average exercise price (in dollars per share)		$ 6.82	$ 6.82
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

STOCK INCENTIVE PLANS - Summary

STOCK INCENTIVE PLANS - Summary of Restricted Stock Units and Performance-based Restricted Stock Units Activity (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Stock-based compensation expense	$ 1,284	$ 1,461
Restricted Stock Units and Performance-based Restricted Stock Units
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)	260,000
Granted (in shares)	259,520
Vested (in shares)	(23,337)
Canceled (in shares)	(325)
Outstanding, ending balance (in shares)	495,858
Stock-based compensation expense	$ 58
Estimated unrecognized share-based compensation expense	$ 2,200

STOCK INCENTIVE PLANS - Summa_2

STOCK INCENTIVE PLANS - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Number of Shares
Outstanding, beginning balance (in shares)	4,132,671
Options granted (in shares)	1,067,150
Options exercised (in shares)	0
Options canceled (in shares)	(5,289)
Outstanding, ending balance (in shares)	5,194,532	4,132,671
Vested and expected to vest (in shares)	5,194,532
Exercisable (in shares)	2,656,448
Weighted Average Exercise Price
Outstanding, beginning balance (in dollars per share)	$ 6.58
Options granted (in dollars per share)	2.61
Options exercised (in dollars per share)	0
Options canceled (in dollars per share)	6.93
Outstanding, ending balance (in dollars per share)	5.76	$ 6.58
Vested and expected to vest (in dollars per share)	5.76
Exercisable (in dollars per share)	$ 7.27
Weighted Average Remaining Contractual Life
Outstanding	7 years 8 months 12 days	7 years 4 months 28 days
Vested and expected to vest	7 years 8 months 12 days
Exercisable	6 years 5 months 27 days
Total Aggregate Intrinsic Value
Outstanding	$ 191	$ 25
Vested and expected to vest	191
Exercisable	$ 148

STOCK INCENTIVE PLANS - Schedul

STOCK INCENTIVE PLANS - Schedule of Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total	$ 1,284	$ 1,461
Research and development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total	643	640
General and administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total	$ 641	$ 821

SIGNIFICANT AGREEMENTS AND CO_2

SIGNIFICANT AGREEMENTS AND CONTRACTS (Details) - Subaward Agreement - CD201 product candidate $ in Millions	Mar. 30, 2017USD ($)
Revenue Recognition, Multiple-deliverable Arrangements [Line Items]
Qualifying development expenses to be reimbursed by CARB-X upon acceptance of new initial drug application	$ 3.9
Qualifying development expenses to be reimbursed by CARB-X through a Phase 1 clinical trial of CD201	$ 3
Agreement termination, written notice period	30 days

COMMITMENTS AND CONTINGENCIES -

COMMITMENTS AND CONTINGENCIES - Additional Information (Details)	Jan. 01, 2019USD ($)	Mar. 31, 2019USD ($)optionclaim1
Commitments and Contingencies Disclosure [Abstract]
Number of claim or actions pending | claim1		0
Lease renewal term	36 months	2 years
Base rent	$ 70,000
Number of renewal options | option		2
Annual increases in base rent		3.00%
Adjusted incremental borrowing rate used in measuring lease liability		10.80%
Lease, weighted average remaining lease term		2 years 9 months
Lease payments		$ 233,000
Lease cost		$ 301,000
Variable lease and short-term lease term included within operating lease cost (greater than)		30 days
Contract termination, notice period		30 days

COMMITMENTS AND CONTINGENCIES_2

COMMITMENTS AND CONTINGENCIES - Amount, Timing and Uncertainty of Cash Flows from Operating Lease (Details) $ in Thousands	Mar. 31, 2019USD ($)
Commitments and Contingencies Disclosure [Abstract]
2019	$ 701
2021	963
2021	992
Total undiscounted operating lease payments	2,656
Less: Imputed interest	372
Present value of lease payments	$ 2,284

COMMITMENTS AND CONTINGENCIES_3

COMMITMENTS AND CONTINGENCIES - Supplemental Balance Sheet Information (Details) $ in Thousands	Mar. 31, 2019USD ($)
Commitments and Contingencies Disclosure [Abstract]
Operating lease right-of-use asset	$ 2,131
Current portion of lease liability	730
Lease liability	1,554
Total operating lease liability	$ 2,284