Cidara Therapeutics (CDTX) 10-Q 8 Nov 17 2017 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2017	Oct. 31, 2017
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q3
Entity Registrant Name	Cidara Therapeutics, Inc.
Entity Central Index Key	1,610,618
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		20,238,143

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 54,276	$ 85,367
Short-term investments	9,876	19,252
Accounts receivable	321	0
Prepaid expenses and other current assets	1,730	779
Total current assets	66,203	105,398
Property and equipment, net	1,043	1,374
Other assets	190	190
Total assets	67,436	106,962
Current liabilities:
Accounts payable	1,777	2,909
Accrued liabilities	3,186	3,338
Accrued compensation and benefits	1,987	2,662
Current portion of term loan	1,667	0
Total current liabilities	8,617	8,909
Term loan, less debt issuance costs	8,185	9,794
Other long-term liabilities	61	80
Total liabilities	16,863	18,783
Commitments and contingencies
Stockholders' equity:
Preferred stock, $0.0001 par value; 10,000,000 shares authorized and no shares issued or outstanding at September 30, 2017 and December 31, 2016, respectively	0	0
Common stock, $0.0001 par value; 200,000,000 shares authorized at September 30, 2017 and December 31, 2016; 16,879,006 and 16,865,737 shares issued and outstanding, respectively, at September 30, 2017; 16,837,126 and 16,773,232 shares issued and outstanding, respectively, at December 31, 2016	2	2
Additional paid-in capital	186,534	181,840
Accumulated other comprehensive loss	(1)	(1)
Accumulated deficit	(135,962)	(93,662)
Total stockholders' equity	50,573	88,179
Total liabilities and stockholders' equity	$ 67,436	$ 106,962

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	16,879,006	16,837,126
Common stock, shares outstanding	16,865,737	16,773,232

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss (unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Operating expenses:
Research and development	$ 9,159	$ 8,729	$ 32,593	$ 24,389
General and administrative	3,090	3,607	9,669	9,694
Total operating expenses	12,249	12,336	42,262	34,083
Loss from operations	(12,249)	(12,336)	(42,262)	(34,083)
Other income (expense):
Interest income (expense), net	(8)	109	(38)	312
Total other income (expense)	(8)	109	(38)	312
Net loss	(12,257)	(12,227)	(42,300)	(33,771)
Other comprehensive loss:
Unrealized loss on short-term investments	(1)	(13)	0	(9)
Comprehensive loss	$ (12,258)	$ (12,240)	$ (42,300)	$ (33,780)
Basic and diluted net loss per share (in dollars per share)	$ (0.73)	$ (0.88)	$ (2.51)	$ (2.44)
Shares used to compute basic and diluted net loss per share (in shares)	16,864,211	13,910,145	16,830,749	13,863,453

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Operating activities:
Net loss	$ (42,300)	$ (33,771)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	528	547
Stock-based compensation	4,206	3,254
Non-cash interest expense	58	0
Amortization of discount or premium on short-term investments	(45)	(127)
Deferred rent	(19)	(4)
Changes in assets and liabilities:
Accounts receivable	(337)	0
Prepaid expenses and other current assets	(952)	(506)
Accounts payable and accrued liabilities	(1,185)	1,607
Accrued compensation	(372)	1,072
Other assets	0	(117)
Net cash used in operating activities	(40,418)	(28,045)
Investing activities:
Purchases of short-term investments	(9,880)	(69,617)
Maturities of short-term investments	19,300	60,000
Purchases of property and equipment	(166)	(287)
Net cash provided by (used in) investing activities	9,254	(9,904)
Financing activities:
Proceeds from exercise of stock options	152	70
Repurchase of unvested restricted stock	(79)	0
Debt issuance costs	0	(24)
Deferred public offering costs	0	(37)
Net cash provided by financing activities	73	9
Net decrease in cash and cash equivalents	(31,091)	(37,940)
Cash and cash equivalents at beginning of period	85,367	62,562
Cash and cash equivalents at end of period	54,276	24,622
Supplemental disclosure of cash flows:
Interest paid	378	0
Non-cash investing activities:
Property and equipment acquired but not yet paid	16	38
Non-cash financing activities:
Vesting of early exercised stock options	35	166
Purchase of shares pursuant to Employee Stock Purchase Plan	$ 301	$ 294

THE COMPANY AND BASIS OF PRESEN

THE COMPANY AND BASIS OF PRESENTATION	9 Months Ended
	Sep. 30, 2017
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 product portfolio is comprised of proprietary product candidates for the treatment of serious fungal and bacterial infections. In March 2016, the Company formed a wholly-owned subsidiary, Cidara Therapeutics UK Limited, in England 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 accompanying condensed consolidated financial statements have been prepared assuming the Company will continue as a going concern, which contemplates the realization of assets and the satisfaction of liabilities in the normal course of business. The Company has experienced net losses and negative cash flows from operating activities since its inception. At September 30, 2017 , the Company had an accumulated deficit of $136.0 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. The Company has prepared cash flow forecasts which indicate, based on its current cash resources available and the October 2017 private placement of common stock (see Note 10), that it will have sufficient resources to fund its business, including its ongoing clinical trials, for at least the next 12 months from the date of this filing. The Company will need to raise additional capital to fund its losses from operations. It anticipates raising capital through debt and equity financing, through government funding or through collaborations or partnerships with other entities. Debt or equity financing, government funding or collaborations and partnerships with other entities may not be available on a timely basis on terms acceptable to the Company, or at all. If the Company is not able to secure adequate additional funding, the Company may be forced to delay, reduce or eliminate its research and development programs or future commercialization efforts, or to make reductions in spending, extend payment terms with suppliers, liquidate or grant rights to assets where possible, or suspend or curtail planned programs. 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 September 30, 2017 and 2016 . Basis of Consolidation —The consolidated financial statements include the accounts of the Company and its wholly-owned subsidiary. 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, as well as 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 common shares used to account for share-based compensation and certain accruals, including those related to preclinical 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	9 Months Ended
	Sep. 30, 2017
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 income (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 all four of the following criteria are met: (1) persuasive evidence of an arrangement exists; (2) delivery of the products and/or services has occurred; (3) the selling price is fixed or determinable; and (4) collectibility is reasonably assured. Grant Funding —The Company has received research and development funding through a grant from a nonprofit organization. The Company has evaluated the terms of the grant 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 preclinical and clinical trial costs. The Company accrues preclinical 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. Costs incurred in purchasing technology assets and intellectual property are charged to research and development expense if the technology has not been conclusively proven to be feasible and has no alternative future use. 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 gains (losses) on marketable securities. Comprehensive gains (losses) have been reflected in the condensed consolidated statements of operations and comprehensive loss and as a separate component of the statements of convertible preferred stock and stockholders’ equity (deficit) for all periods presented. Stock-based Compensation —The Company accounts for stock-based compensation expense related to employee 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) granted to employees 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 accounts for stock options, RSUs, and PRSUs granted to non-employees using the fair value approach. These stock-based awards are subject to periodic revaluation over their vesting terms. Net Loss Per Share —Basic net loss per share is computed by dividing the net loss 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 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 convertible preferred stock, unvested restricted common stock subject to repurchase, warrants, and RSUs and options outstanding under the Company’s stock option plans. For all periods presented, there is no difference in the number of shares used to calculate basic and diluted shares outstanding. 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): September 30, 2017 2016 Common stock options and RSUs issued and outstanding 3,323,599 2,343,644 Common stock warrants 17,331 — Common stock subject to repurchase 13,269 79,807 Total 3,354,199 2,423,451 Fair Value of Financial Instruments —The Company follows authoritative guidance 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, marketable securities, 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 Company believes that the fair value of long-term debt approximates its carrying value. Recently Issued Accounting Standards —During 2014, the FASB issued ASU 2014-09, "Revenue from Contracts with Customers ," which outlines a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes most current revenue recognition guidance, including industry-specific guidance. ASU 2014-09 outlines a five-step process for revenue recognition that focuses on transfer of control, as opposed to transfer of risk and rewards, and also requires enhanced disclosures regarding the nature, amount, timing, and uncertainty of revenues and cash flows from contracts with customers. Numerous ASUs were issued in 2016 to require additional disclosures, to provide clarification on a number of specific issues pertaining to ASU 2014-09, and to defer the effective date for ASU 2014-09 to interim and annual periods beginning after December 31, 2017. The Company is currently evaluating the impact of the new standard on its CARB-X Subaward Agreement. Given the timing of the signing of the contract the Company elected not to early adopt the guidance. The Company’s evaluation of the new guidance is ongoing, as is the assessment of the adoption method and the ultimate impact the adoption of this standard will have on the Company's consolidated financial statements. During 2017, the FASB issued ASU No. 2017-09, " Compensation - Stock Compensation: Scope of Modification Accounting ," which provides clarity and guidance around which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting in Topic 718. The standard is effective for interim and annual periods beginning after December 15, 2017. The adoption of this guidance is not expected to have a material impact on the Company's financial statements.

SHORT-TERM INVESTMENTS

SHORT-TERM INVESTMENTS	9 Months Ended
	Sep. 30, 2017
Investments, Debt and Equity Securities [Abstract]
SHORT-TERM INVESTMENTS	SHORT-TERM INVESTMENTS The following table summarizes the available-for-sale securities held at September 30, 2017 and December 31, 2016 (in thousands): As of September 30, 2017 Amortized Cost Unrealized Gains Unrealized Losses Fair Value Corporate debt $ 9,877 $ — $ (1 ) $ 9,876 Total $ 9,877 $ — $ (1 ) $ 9,876 As of December 31, 2016 Amortized Cost Unrealized Gains Unrealized Losses Fair Value Commercial paper $ 19,253 $ 1 $ (2 ) $ 19,252 Total $ 19,253 $ 1 $ (2 ) $ 19,252 All available-for-sale securities held at September 30, 2017 and December 31, 2016 had maturities of less than one year . Unrealized gains and losses on available-for-sale securities are included as a component of other comprehensive loss. The securities in unrealized loss positions had not been in a continuous unrealized loss position for 12 months or longer. The Company reviews its investments to identify and evaluate investments that have an indication of possible other-than-temporary impairment. Factors considered in determining whether a loss is other-than-temporary include the length of time and extent to which fair value has been less than the cost basis, the financial condition and near-term prospects of the investee, and the Company’s intent and ability to hold the investment for a period of time sufficient to allow for any anticipated recovery in market value.

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	9 Months Ended
	Sep. 30, 2017
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 that should be determined based on assumptions that market participants would use in pricing an asset or liability. 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 in which there is little or no market data, which require the reporting entity to develop its own assumptions, and 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 with Level 2 as these instruments are valued using observable market inputs including reported trades, broker/dealer quotes, bids and/or offers. 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 September 30, 2017 Assets: Money market funds $ 16,539 $ 16,539 $ — $ — U.S. Treasury reverse repurchase agreements 37,500 — 37,500 — Corporate debt 9,876 — 9,876 Total assets at fair value $ 63,915 $ 16,539 $ 47,376 $ — December 31, 2016 Assets: Money market funds $ 84,830 $ 84,830 $ — $ — Commercial paper 19,252 — 19,252 — Total assets at fair value $ 104,082 $ 84,830 $ 19,252 $ —

DEBT

DEBT	9 Months Ended
	Sep. 30, 2017
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 and subject to the achievement of positive Phase 2 clinical results from the STRIVE study (the "Milestone"), the Company may, at its sole discretion through October 3, 2018, borrow from the Lender up to an additional $10.0 million (the "Term B Loan," and together with Term A Loan, the "Term Loans"). 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 Phase 2 clinical data from the rezafungin (formerly known as CD101 IV) program by March 31, 2018, 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 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 Term Loans mature on October 3, 2020 (the "Maturity Date"). Payments under the Term Loans will be interest-only through April 2, 2018, which will be extended by six months if the Milestone event is achieved. The interest-only period will be followed by 30 monthly payments of principal and interest, provided that there will be 24 monthly payments if the Milestone event is achieved. 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 1.0% . At September 30, 2017 , the Term Loans bear interest at 5.25 %. As of September 30, 2017 , future principal payments due under the Term A Loan are as follows (in thousands): Year ended: December 31, 2017 $ — December 31, 2018 2,667 December 31, 2019 4,000 December 31, 2020 3,333 Total future principal payments due under the Term A Loan $ 10,000

STOCKHOLDERS' EQUITY

STOCKHOLDERS' EQUITY	9 Months Ended
	Sep. 30, 2017
Equity [Abstract]
STOCKHOLDERS' EQUITY	STOCKHOLDERS’ EQUITY 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 and no shares of preferred stock issued or outstanding at September 30, 2017 . Common Stock —The Company had 200,000,000 shares of common stock authorized as of September 30, 2017 . 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): September 30, 2017 December 31, 2016 Stock options and RSUs issued and outstanding 3,323,599 2,295,393 Authorized for future stock awards under the Company's option plans 1,022,967 1,404,933 Authorized for future issuance under the ESPP 423,098 306,813 Common stock warrants 17,331 17,331 Total 4,786,995 4,024,470

STOCK INCENTIVE PLANS

STOCK INCENTIVE PLANS	9 Months Ended
	Sep. 30, 2017
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 year period. Certain stock options are subject to acceleration of vesting in the event of certain change of control transactions. The stock options may be granted for a term of up to 10 years from the date of grant. The exercise price for stock options granted under the 2015 EIP must be at a price no less than 100% of the estimated fair value of the shares on the date of grant as determined by the board of directors, provided that for an incentive stock option granted to an employee who at the time of grant owns stock representing more than 10% of the voting power of all classes of stock of the Company, the exercise price shall be no less than 110% of the estimated value on the date of grant. 2015 Employee Stock Purchase Plan In March 2015, the Company’s board of directors and stockholders approved and adopted the 2015 Employee Stock Purchase Plan, or the ESPP. The number of shares of stock available for issuance under the ESPP will be automatically increased each January 1 by the lower of (i) 1% of the outstanding number of shares of the Company’s common stock on the immediately preceding December 31, (ii) 490,336 shares, or (iii) such lesser number as determined by the Company’s board of directors. The ESPP allows substantially all employees to purchase the Company’s common stock through a payroll deduction at a price equal to 85% of the lower of the fair market value of the stock as of the beginning or the end of each purchase period. An employee’s payroll deductions under the ESPP are limited to 15% of the employee’s eligible compensation. During the nine months ended September 30, 2017 , 52,086 shares were issued pursuant to the ESPP. Restricted Stock The Company permits exercise of certain stock options prior to vesting. Any such unvested shares are restricted and subject to repurchase by the Company until the conditions for vesting are met. At September 30, 2017 and December 31, 2016 , the liabilities for the cash received from the early exercise of stock options were $30,000 and $144,000 , respectively, and were classified in accrued liabilities on the balance sheet. The Company reduces the liability as the underlying shares vest in accordance with the vesting terms outlined in the stock option agreements, which are generally 4 years . At September 30, 2017 , 13,269 unvested shares were subject to repurchase by the Company. Restricted Stock Units The following table summarizes RSU and PRSU activity during the nine months ended September 30, 2017 : Number of Outstanding at December 31, 2016 — RSUs and PRSUs granted 240,000 RSUs and PRSUs vested — RSUs and PRSUs canceled (10,000 ) Outstanding at September 30, 2017 230,000 For the nine months ended September 30, 2017 , stock-based compensation expense related to RSUs and PRSUs was approximately $9,000 . At September 30, 2017 , estimated unrecognized compensation expense related to RSUs and PRSUs granted to employees was approximately $1.5 million . Stock Options The following table summarizes stock option activity during the nine months ended September 30, 2017 : Number of Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Life in Years Total Aggregate Intrinsic Value (in thousands) Outstanding at December 31, 2016 2,295,393 $ 7.82 8.20 $ 6,774 Options granted 1,013,951 7.77 Options exercised (27,246 ) 5.58 Options canceled (188,499 ) 9.15 Outstanding at September 30, 2017 3,093,599 $ 7.75 8.27 $ 4,007 Vested and expected to vest at September 30, 2017 3,093,599 $ 7.75 8.27 $ 4,007 Exercisable at September 30, 2017 1,518,239 $ 7.37 7.69 $ 2,763 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 Nine Months Ended 2017 2016 2017 2016 Research and development $ 666 $ 669 $ 1,805 $ 1,550 General and administrative 889 641 2,401 1,704 Total $ 1,555 $ 1,310 $ 4,206 $ 3,254 The weighted-average grant date fair value of employee stock options granted by the Company during the nine months ended September 30, 2017 was $5.55 per share. The total grant date fair value of employee stock options that vested during the nine months ended September 30, 2017 was $3.7 million . As of September 30, 2017 , total unrecognized share-based compensation expense related to unvested employee stock options of the Company was approximately $8.7 million . This unrecognized compensation cost is expected to be recognized over a weighted-average period of approximately 2.0 years. As of September 30, 2017 , total unrecognized compensation expense related to the ESPP was approximately $0.6 million . This unrecognized compensation cost is expected to be recognized over approximately 1.1 years .

SIGNIFICANT AGREEMENTS AND CONT

SIGNIFICANT AGREEMENTS AND CONTRACTS	9 Months Ended
	Sep. 30, 2017
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), and National Institute of Allergy and Infectious Diseases (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 supports development of the Company's CD201 product candidate and back-up candidates. The back-up candidates include antibody-drug conjugates that the Company is testing in various animal models of bacterial infections. 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 will 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. Under the Subaward Agreement, the Company is reimbursed for direct costs incurred plus allowable indirect costs which consist of fringe benefits and allowable general and administrative expenses. For the three and nine month periods ended September 30, 2017 , the Company recognized reductions to research and development expenses of $0.2 million and $0.4 million , respectively, for costs eligible for reimbursement under the Subaward Agreement. As of September 30, 2017 , billed accounts receivable were $0.1 million and unbilled accounts receivable were $0.2 million related to reimbursable expenses under the Subaward Agreement.

COMMITMENTS AND CONTINGENCIES

COMMITMENTS AND CONTINGENCIES	9 Months Ended
	Sep. 30, 2017
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 September 30, 2017 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 —In June 2014, the Company entered into an operating lease agreement for laboratory and office space in San Diego, California. Amendments for additional space were entered into in February 2015, March 2015, and August 2015. The lease expires in December 2018 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 July. Rent expense is being recorded on a straight-line basis over the life of the lease. Future minimum payments required under the lease as of September 30, 2017 are summarized as follows (in thousands): 2017 $ 184 2018 746 Total minimum lease payments $ 930 Rent expense was $530,000 and $537,000 for the nine months ended September 30, 2017 and 2016 , respectively. 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.

SUBSEQUENT EVENTS

SUBSEQUENT EVENTS	9 Months Ended
	Sep. 30, 2017
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	SUBSEQUENT EVENTS Private Placement —In October 2017, the Company closed a private placement transaction with certain accredited investors pursuant to which an aggregate of 3,360,000 shares of common stock were sold at a price of $6.00 per share. The Company received net proceeds of approximately $19.0 million after deducting commissions and offering expenses.

SUMMARY OF SIGNIFICANT ACCOUN16

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	9 Months Ended
	Sep. 30, 2017
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 accompanying condensed consolidated financial statements have been prepared assuming the Company will continue as a going concern, which contemplates the realization of assets and the satisfaction of liabilities in the normal course of business. The Company has experienced net losses and negative cash flows from operating activities since its inception. At September 30, 2017 , the Company had an accumulated deficit of $136.0 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. The Company has prepared cash flow forecasts which indicate, based on its current cash resources available and the October 2017 private placement of common stock (see Note 10), that it will have sufficient resources to fund its business, including its ongoing clinical trials, for at least the next 12 months from the date of this filing. The Company will need to raise additional capital to fund its losses from operations. It anticipates raising capital through debt and equity financing, through government funding or through collaborations or partnerships with other entities. Debt or equity financing, government funding or collaborations and partnerships with other entities may not be available on a timely basis on terms acceptable to the Company, or at all. If the Company is not able to secure adequate additional funding, the Company may be forced to delay, reduce or eliminate its research and development programs or future commercialization efforts, or to make reductions in spending, extend payment terms with suppliers, liquidate or grant rights to assets where possible, or suspend or curtail planned programs. Any of these actions could materially harm the Company’s business, results of operations and future prospects.
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 September 30, 2017 and 2016 .
Basis of Consolidation	Basis of Consolidation —The consolidated financial statements include the accounts of the Company and its wholly-owned subsidiary. 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, as well as 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 common shares used to account for share-based compensation and certain accruals, including those related to preclinical 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 income (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 all four of the following criteria are met: (1) persuasive evidence of an arrangement exists; (2) delivery of the products and/or services has occurred; (3) the selling price is fixed or determinable; and (4) collectibility is reasonably assured. Under the Subaward Agreement, the Company is reimbursed for direct costs incurred plus allowable indirect costs which consist of fringe benefits and allowable general and administrative expenses.
Grant Funding and Research and Development Costs	Grant Funding —The Company has received research and development funding through a grant from a nonprofit organization. The Company has evaluated the terms of the grant 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 preclinical and clinical trial costs. The Company accrues preclinical 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. Costs incurred in purchasing technology assets and intellectual property are charged to research and development expense if the technology has not been conclusively proven to be feasible and has no alternative future use.
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 gains (losses) on marketable securities. Comprehensive gains (losses) have been reflected in the condensed consolidated statements of operations and comprehensive loss and as a separate component of the statements of convertible preferred stock and stockholders’ equity (deficit) for all periods presented.
Stock-based Compensation	Stock-based Compensation —The Company accounts for stock-based compensation expense related to employee 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) granted to employees 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 accounts for stock options, RSUs, and PRSUs granted to non-employees using the fair value approach. These stock-based awards are subject to periodic revaluation over their vesting terms.
Net Loss Per Share	Net Loss Per Share —Basic net loss per share is computed by dividing the net loss 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 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 convertible preferred stock, unvested restricted common stock subject to repurchase, warrants, and RSUs and options outstanding under the Company’s stock option plans. For all periods presented, there is no difference in the number of shares used to calculate basic and diluted shares outstanding.
Fair Value of Financial Instruments	Fair Value of Financial Instruments —The Company follows authoritative guidance 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, marketable securities, 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 Company believes that the fair value of long-term debt approximates its carrying value.
Recently Issued Accounting Standards	Recently Issued Accounting Standards —During 2014, the FASB issued ASU 2014-09, "Revenue from Contracts with Customers ," which outlines a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes most current revenue recognition guidance, including industry-specific guidance. ASU 2014-09 outlines a five-step process for revenue recognition that focuses on transfer of control, as opposed to transfer of risk and rewards, and also requires enhanced disclosures regarding the nature, amount, timing, and uncertainty of revenues and cash flows from contracts with customers. Numerous ASUs were issued in 2016 to require additional disclosures, to provide clarification on a number of specific issues pertaining to ASU 2014-09, and to defer the effective date for ASU 2014-09 to interim and annual periods beginning after December 31, 2017. The Company is currently evaluating the impact of the new standard on its CARB-X Subaward Agreement. Given the timing of the signing of the contract the Company elected not to early adopt the guidance. The Company’s evaluation of the new guidance is ongoing, as is the assessment of the adoption method and the ultimate impact the adoption of this standard will have on the Company's consolidated financial statements. During 2017, the FASB issued ASU No. 2017-09, " Compensation - Stock Compensation: Scope of Modification Accounting ," which provides clarity and guidance around which changes to the terms or conditions of a share-based payment award require an entity to apply modification accounting in Topic 718. The standard is effective for interim and annual periods beginning after December 15, 2017. The adoption of this guidance is not expected to have a material impact on the Company's financial statements.

SUMMARY OF SIGNIFICANT ACCOUN17

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)	9 Months Ended
	Sep. 30, 2017
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): September 30, 2017 2016 Common stock options and RSUs issued and outstanding 3,323,599 2,343,644 Common stock warrants 17,331 — Common stock subject to repurchase 13,269 79,807 Total 3,354,199 2,423,451

SHORT-TERM INVESTMENTS (Tables)

SHORT-TERM INVESTMENTS (Tables)	9 Months Ended
	Sep. 30, 2017
Investments, Debt and Equity Securities [Abstract]
Summary of Available-for-Sale Securities	The following table summarizes the available-for-sale securities held at September 30, 2017 and December 31, 2016 (in thousands): As of September 30, 2017 Amortized Cost Unrealized Gains Unrealized Losses Fair Value Corporate debt $ 9,877 $ — $ (1 ) $ 9,876 Total $ 9,877 $ — $ (1 ) $ 9,876 As of December 31, 2016 Amortized Cost Unrealized Gains Unrealized Losses Fair Value Commercial paper $ 19,253 $ 1 $ (2 ) $ 19,252 Total $ 19,253 $ 1 $ (2 ) $ 19,252

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	9 Months Ended
	Sep. 30, 2017
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 September 30, 2017 Assets: Money market funds $ 16,539 $ 16,539 $ — $ — U.S. Treasury reverse repurchase agreements 37,500 — 37,500 — Corporate debt 9,876 — 9,876 Total assets at fair value $ 63,915 $ 16,539 $ 47,376 $ — December 31, 2016 Assets: Money market funds $ 84,830 $ 84,830 $ — $ — Commercial paper 19,252 — 19,252 — Total assets at fair value $ 104,082 $ 84,830 $ 19,252 $ —

DEBT (Tables)

DEBT (Tables)	9 Months Ended
	Sep. 30, 2017
Debt Disclosure [Abstract]
Schedule of Future Principal Payments	As of September 30, 2017 , future principal payments due under the Term A Loan are as follows (in thousands): Year ended: December 31, 2017 $ — December 31, 2018 2,667 December 31, 2019 4,000 December 31, 2020 3,333 Total future principal payments due under the Term A Loan $ 10,000

STOCKHOLDERS' EQUITY (Tables)

STOCKHOLDERS' EQUITY (Tables)	9 Months Ended
	Sep. 30, 2017
Equity [Abstract]
Schedule of Common Stock Reserved for Future Issuance	Common stock reserved for future issuance is as follows (in common stock equivalent shares): September 30, 2017 December 31, 2016 Stock options and RSUs issued and outstanding 3,323,599 2,295,393 Authorized for future stock awards under the Company's option plans 1,022,967 1,404,933 Authorized for future issuance under the ESPP 423,098 306,813 Common stock warrants 17,331 17,331 Total 4,786,995 4,024,470

STOCK INCENTIVE PLANS (Tables)

STOCK INCENTIVE PLANS (Tables)	9 Months Ended
	Sep. 30, 2017
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 nine months ended September 30, 2017 : Number of Outstanding at December 31, 2016 — RSUs and PRSUs granted 240,000 RSUs and PRSUs vested — RSUs and PRSUs canceled (10,000 ) Outstanding at September 30, 2017 230,000
Summary of Stock Option Activity	The following table summarizes stock option activity during the nine months ended September 30, 2017 : Number of Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Life in Years Total Aggregate Intrinsic Value (in thousands) Outstanding at December 31, 2016 2,295,393 $ 7.82 8.20 $ 6,774 Options granted 1,013,951 7.77 Options exercised (27,246 ) 5.58 Options canceled (188,499 ) 9.15 Outstanding at September 30, 2017 3,093,599 $ 7.75 8.27 $ 4,007 Vested and expected to vest at September 30, 2017 3,093,599 $ 7.75 8.27 $ 4,007 Exercisable at September 30, 2017 1,518,239 $ 7.37 7.69 $ 2,763
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 Nine Months Ended 2017 2016 2017 2016 Research and development $ 666 $ 669 $ 1,805 $ 1,550 General and administrative 889 641 2,401 1,704 Total $ 1,555 $ 1,310 $ 4,206 $ 3,254

COMMITMENTS AND CONTINGENCIES (

COMMITMENTS AND CONTINGENCIES (Tables)	9 Months Ended
	Sep. 30, 2017
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Payments Required	Future minimum payments required under the lease as of September 30, 2017 are summarized as follows (in thousands): 2017 $ 184 2018 746 Total minimum lease payments $ 930

THE COMPANY AND BASIS OF PRES24

THE COMPANY AND BASIS OF PRESENTATION (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2017USD ($)segment	Dec. 31, 2016USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accumulated deficit | $	$ 135,962	$ 93,662
Number of operating segments | segment	1

SUMMARY OF SIGNIFICANT ACCOUN25

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details) - shares	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
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)	3,354,199	2,423,451
Common stock options and RSUs 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)	3,323,599	2,343,644
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)	17,331	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)	13,269	79,807

SHORT-TERM INVESTMENTS (Details

SHORT-TERM INVESTMENTS (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	$ 9,877	$ 19,253
Unrealized Gains	0	1
Unrealized Losses	(1)	(2)
Fair Value	$ 9,876	$ 19,252
Maturity of available-for-sale securities (less than) (term)	1 year	1 year
Corporate debt
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	$ 9,877
Unrealized Gains	0
Unrealized Losses	(1)
Fair Value	$ 9,876
Commercial paper
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost		$ 19,253
Unrealized Gains		1
Unrealized Losses		(2)
Fair Value		$ 19,252

FAIR VALUE MEASUREMENTS (Detail

FAIR VALUE MEASUREMENTS (Details) - Fair Value Measurements, Recurring - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Assets:
Total assets at fair value	$ 63,915	$ 104,082
Money market funds
Assets:
Fair value of assets	16,539	84,830
U.S. Treasury reverse repurchase agreements
Assets:
Fair value of assets	37,500
Corporate debt
Assets:
Fair value of assets	9,876
Commercial paper
Assets:
Fair value of assets		19,252
LEVEL 1
Assets:
Total assets at fair value	16,539	84,830
LEVEL 1 | Money market funds
Assets:
Fair value of assets	16,539	84,830
LEVEL 1 | U.S. Treasury reverse repurchase agreements
Assets:
Fair value of assets	0
LEVEL 1 | Corporate debt
Assets:
Fair value of assets	0
LEVEL 1 | Commercial paper
Assets:
Fair value of assets		0
LEVEL 2
Assets:
Total assets at fair value	47,376	19,252
LEVEL 2 | Money market funds
Assets:
Fair value of assets	0	0
LEVEL 2 | U.S. Treasury reverse repurchase agreements
Assets:
Fair value of assets	37,500
LEVEL 2 | Corporate debt
Assets:
Fair value of assets	9,876
LEVEL 2 | Commercial paper
Assets:
Fair value of assets		19,252
LEVEL 3
Assets:
Total assets at fair value	0	0
LEVEL 3 | Money market funds
Assets:
Fair value of assets	0	0
LEVEL 3 | U.S. Treasury reverse repurchase agreements
Assets:
Fair value of assets	0
LEVEL 3 | Corporate debt
Assets:
Fair value of assets
LEVEL 3 | Commercial paper
Assets:
Fair value of assets		$ 0

DEBT - Narrative (Details)

DEBT - Narrative (Details) - Term Loan	Oct. 03, 2016USD ($)payment	Sep. 30, 2017
Loan Agreement
Debt Instrument [Line Items]
Term loans, maximum borrowing capacity	$ 20,000,000
Period of extension if the Milestone event is achieved	6 months
Number of equal monthly payments of principal and interest | payment	30
Number of equal monthly payments if the Milestone amount is achieved | payment	24
Variable annual rate	4.50%	5.25%
Loan Agreement | Prime Rate
Debt Instrument [Line Items]
Prime interest rate	1.00%
Term A Loan
Debt Instrument [Line Items]
Borrowed from the Lender	$ 10,000,000
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	Sep. 30, 2017USD ($)
Year ended:
December 31, 2017	$ 0
December 31, 2018	2,667
December 31, 2019	4,000
December 31, 2020	3,333
Total future principal payments due under the Term A Loan	$ 10,000

STOCKHOLDERS' EQUITY - Narrativ

STOCKHOLDERS' EQUITY - Narrative (Details)	9 Months Ended
	Sep. 30, 2017USD ($)vote_per_shareshares	Dec. 31, 2016shares
Equity [Abstract]
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Preferred stock issued (in shares)	0	0
Preferred stock outstanding (in shares)	0	0
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

STOCKHOLDERS' EQUITY - Schedule

STOCKHOLDERS' EQUITY - Schedule of Common Stock Reserved for Future Issuance (Details) - shares	Sep. 30, 2017	Dec. 31, 2016
Class of Stock [Line Items]
Total (in shares)	4,786,995	4,024,470
Stock options and RSUs issued and outstanding
Class of Stock [Line Items]
Total (in shares)	3,323,599	2,295,393
Authorized for future stock awards under the Company's option plans
Class of Stock [Line Items]
Total (in shares)	1,022,967	1,404,933
Authorized for future issuance under the ESPP
Class of Stock [Line Items]
Total (in shares)	423,098	306,813
Common stock warrants
Class of Stock [Line Items]
Total (in shares)	17,331	17,331

STOCK INCENTIVE PLANS - Narrat

STOCK INCENTIVE PLANS - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	9 Months Ended
	Mar. 31, 2015	Sep. 30, 2017	Dec. 31, 2016
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)		$ 5.55
Grant date fair value of employee stock options vested		$ 3,700
Total unrecognized share-based compensation expense related to unvested employee stock options		$ 8,700
Period to recognize unrecognized compensation cost		2 years
ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Automatic increase in shares of stock available (as a percent)	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)		52,086
Period to recognize unrecognized compensation cost		1 year 26 days
Estimated unrecognized share-based compensation expense		$ 600
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period		4 years
Cash received from early exercise of stock options		$ 30	$ 144
Subject to repurchase | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unvested shares subject to repurchase (in shares)		13,269
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 increase in shares of stock available (as a percent)	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 (as a percent)	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 ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Stock-based compensation expense	$ 1,555,000	$ 1,310,000	$ 4,206,000	$ 3,254,000
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)			0
Granted (in shares)			240,000
Vested (in shares)			0
Canceled (in shares)			(10,000)
Outstanding, ending balance (in shares)	230,000		230,000
Stock-based compensation expense			$ 9,000
Estimated unrecognized share-based compensation expense	$ 1,500,000		$ 1,500,000

STOCK INCENTIVE PLANS - Summa34

STOCK INCENTIVE PLANS - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Number of Shares
Outstanding, beginning balance (in shares)	2,295,393
Options granted (in shares)	1,013,951
Options exercised (in shares)	(27,246)
Options canceled (in shares)	(188,499)
Outstanding, ending balance (in shares)	3,093,599	2,295,393
Vested and expected to vest (in shares)	3,093,599
Exercisable (in shares)	1,518,239
Weighted Average Exercise Price
Outstanding, beginning balance (in dollars per share)	$ 7.82
Options granted (in dollars per share)	7.77
Options exercised (in dollars per share)	5.58
Options canceled (in dollars per share)	9.15
Outstanding, ending balance (in dollars per share)	7.75	$ 7.82
Vested and expected to vest (in dollars per share)	7.75
Exercisable (in dollars per share)	$ 7.37
Weighted Average Remaining Contractual Life
Outstanding, life	8 years 3 months 7 days	8 years 2 months 12 days
Vested and expected to vest, life	8 years 3 months 7 days
Exercisable, life	7 years 8 months 8 days
Total Aggregate Intrinsic Value
Outstanding	$ 4,007	$ 6,774
Vested and expected to vest	4,007
Exercisable	$ 2,763

STOCK INCENTIVE PLANS - Schedul

STOCK INCENTIVE PLANS - Schedule of Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total	$ 1,555	$ 1,310	$ 4,206	$ 3,254
Research and development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total	666	669	1,805	1,550
General and administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total	$ 889	$ 641	$ 2,401	$ 1,704

SIGNIFICANT AGREEMENTS AND CO36

SIGNIFICANT AGREEMENTS AND CONTRACTS (Details) - Subaward Agreement - CD201 product candidate - USD ($) $ in Millions	Mar. 30, 2017	Sep. 30, 2017	Sep. 30, 2017
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 through a Phase 1 clinical trial of CD201	$ 3
Agreement termination, written notice period	30 days
Reduction in research and development expense		$ 0.2	$ 0.4
Billed accounts receivable		0.1	0.1
Unbilled accounts receivable		$ 0.2	$ 0.2

COMMITMENTS AND CONTINGENCIES -

COMMITMENTS AND CONTINGENCIES - Narrative (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2017USD ($)optionclaim1	Sep. 30, 2016USD ($)
Commitments and Contingencies Disclosure [Abstract]
Number of claim or actions pending | claim1	0
Number of options for individual two-year extensions | option	2
Term of optional individual extensions	2 years
Annual increases in base rent (as a percent)	3.00%
Rent expense | $	$ 530	$ 537
Contract termination, notice period	30 days

COMMITMENTS AND CONTINGENCIES38

COMMITMENTS AND CONTINGENCIES - Schedule of Future Minimum Payments Required (Details) $ in Thousands	Sep. 30, 2017USD ($)
Commitments and Contingencies Disclosure [Abstract]
2,017	$ 184
2,018	746
Total minimum lease payments	$ 930

SUBSEQUENT EVENTS (Details)

SUBSEQUENT EVENTS (Details) - Private placement - Subsequent event $ / shares in Units, $ in Millions	1 Months Ended
	Oct. 31, 2017USD ($)$ / sharesshares
Subsequent Event [Line Items]
Common stock sold (in shares) | shares	3,360,000
Price per share (in dollars per share) | $ / shares	$ 6
Net proceeds | $	$ 19