Document and Entity Information
Document and Entity Information - shares | 3 Months Ended | |
Mar. 31, 2017 | May 10, 2017 | |
Document And Entity Information [Abstract] | ||
Document Type | 10-Q | |
Amendment Flag | false | |
Document Period End Date | Mar. 31, 2017 | |
Document Fiscal Year Focus | 2,017 | |
Document Fiscal Period Focus | Q1 | |
Trading Symbol | LIFE | |
Entity Registrant Name | aTYR PHARMA INC | |
Entity Central Index Key | 1,339,970 | |
Current Fiscal Year End Date | --12-31 | |
Entity Filer Category | Smaller Reporting Company | |
Entity Common Stock, Shares Outstanding | 23,806,329 |
Condensed Consolidated Balance
Condensed Consolidated Balance Sheets - USD ($) $ in Thousands | Mar. 31, 2017 | Dec. 31, 2016 |
Current assets: | ||
Cash and cash equivalents | $ 28,900 | $ 38,388 |
Available-for sale investments, short-term | 33,034 | 33,759 |
Prepaid expenses and other assets | 1,848 | 2,621 |
Total current assets | 63,782 | 74,768 |
Available-for sale investments, long-term | 4,002 | |
Property and equipment, net | 1,623 | 1,421 |
Other assets | 330 | 333 |
Total assets | 65,735 | 80,524 |
Current liabilities: | ||
Accounts payable | 1,246 | 2,606 |
Accrued expenses | 4,160 | 5,450 |
Current portion of deferred rent | 49 | 130 |
Current portion of long-term debt | 1,094 | 339 |
Total current liabilities | 6,549 | 8,525 |
Long-term debt, net of current portion and issuance costs | 8,480 | 9,198 |
Commitments and contingencies (Note 3) | ||
Stockholders’ equity: | ||
Common stock, $0.001 par value; authorized shares – 150,000,000 as of March 31, 2017 and December 31, 2016; issued and outstanding shares – 23,780,976 and 23,744,832 as of March 31, 2017 and December 31, 2016, respectively | 24 | 24 |
Additional paid-in capital | 280,134 | 278,832 |
Accumulated other comprehensive loss | (68) | (76) |
Accumulated deficit | (229,384) | (215,979) |
Total stockholders’ equity | 50,706 | 62,801 |
Total liabilities and stockholders’ equity | $ 65,735 | $ 80,524 |
Condensed Consolidated Balance3
Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares | Mar. 31, 2017 | Dec. 31, 2016 |
Statement Of Financial Position [Abstract] | ||
Common stock, par value | $ 0.001 | $ 0.001 |
Common stock, shares authorized | 150,000,000 | 150,000,000 |
Common stock, shares issued | 23,780,976 | 23,744,832 |
Common stock, shares outstanding | 23,780,976 | 23,744,832 |
Condensed Consolidated Statemen
Condensed Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands | 3 Months Ended | |
Mar. 31, 2017 | Mar. 31, 2016 | |
Operating expenses: | ||
Research and development | $ 9,204 | $ 12,000 |
General and administrative | 4,007 | 4,115 |
Total operating expenses | 13,211 | 16,115 |
Loss from operations | (13,211) | (16,115) |
Other income (expense), net | (194) | 28 |
Net loss | $ (13,405) | $ (16,087) |
Net loss per share, basic and diluted | $ (0.56) | $ (0.68) |
Weighted average common stock shares outstanding, basic and diluted | 23,739,057 | 23,631,133 |
Condensed Consolidated Stateme5
Condensed Consolidated Statements of Comprehensive Loss (Unaudited) - USD ($) $ in Thousands | 3 Months Ended | |
Mar. 31, 2017 | Mar. 31, 2016 | |
Statement Of Income And Comprehensive Income [Abstract] | ||
Net loss | $ (13,405) | $ (16,087) |
Other comprehensive gain (loss): | ||
Change in unrealized gain (loss) on available for sale investments, net of tax | 8 | 152 |
Comprehensive loss | $ (13,397) | $ (15,935) |
Condensed Consolidated Stateme6
Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands | 3 Months Ended | |
Mar. 31, 2017 | Mar. 31, 2016 | |
Cash flows from operating activities: | ||
Net loss | $ (13,405) | $ (16,087) |
Adjustments to reconcile net loss to net cash used in operating activities: | ||
Depreciation and amortization | 226 | 233 |
Stock-based compensation | 1,277 | 1,280 |
Amortization of debt discount | (37) | 54 |
Amortization of premium of available-for-sale investment securities | 74 | 264 |
Deferred rent | (81) | (76) |
Changes in operating assets and liabilities | ||
Prepaid expenses and other assets | 776 | 858 |
Accounts payable and accrued expenses | (2,742) | 983 |
Net cash used in operating activities | (13,912) | (12,491) |
Cash flows from investing activities: | ||
Purchase of property and equipment | (262) | (314) |
Purchases of available-for-sale investment securities | (11,489) | (9,994) |
Maturities of available-for-sale investment securities | 16,150 | 24,700 |
Net cash provided by investing activities | 4,399 | 14,392 |
Cash flows from financing activities: | ||
Proceeds from issuance of common stock through option exercises | 25 | 11 |
Repayments on loans payable | (838) | |
Net cash provided by (used in) financing activities | 25 | (827) |
Net change in cash and cash equivalents | (9,488) | 1,074 |
Cash and cash equivalents at beginning of period | 38,388 | 53,025 |
Cash and cash equivalents at the end of period | $ 28,900 | $ 54,099 |
Organization, Business, Basis o
Organization, Business, Basis of Presentation and Summary of Significant Accounting Policies | 3 Months Ended |
Mar. 31, 2017 | |
Accounting Policies [Abstract] | |
Organization, Business, Basis of Presentation and Summary of Significant Accounting Policies | 1. Organization, Business, Basis of Presentation and Summary of Significant Accounting Policies Organization and Business aTyr Pharma, Inc. (we, us, and our) was incorporated in the state of Delaware on September 8, 2005. We are focused on the discovery and clinical development of innovative medicines for patients suffering from severe rare diseases. Principles of Consolidation Our consolidated financial statements include our accounts and our 98% majority-owned subsidiary in Hong Kong, Pangu BioPharma Limited (Pangu BioPharma). All intercompany transactions and balances are eliminated in consolidation. Unaudited Interim Financial Information The accompanying interim condensed consolidated financial statements are unaudited. These unaudited interim financial statements have been prepared in accordance with United States generally accepted accounting principles (GAAP) and following the requirements of the United States Securities and Exchange Commission (SEC) for interim reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by GAAP can be condensed or omitted. In our opinion, the unaudited interim financial statements have been prepared on the same basis as the audited financial statements and include all adjustments, which include only normal recurring adjustments, necessary for the fair presentation of our financial position and our results of operations and cash flows for periods presented. These statements do not include all disclosures required by GAAP and should be read in conjunction with our financial statements and accompanying notes for the fiscal year ended December 31, 2016, contained in our Annual Report on Form 10-K filed with the SEC on March 16, 2017. The results of the interim periods are not necessarily indicative of the results expected for the full fiscal year or any other interim period or any future year or period. Liquidity and Financial Condition We have incurred losses and negative cash flows from operations since our inception. As of March 31, 2017, we had an accumulated deficit of $229.4 million and we expect to continue to incur net losses for the foreseeable future. We believe that our existing cash, cash equivalents and available-for-sale investments, of $61.9 million as of March 31, 2017 will be sufficient to meet our anticipated cash requirements for a period of one year from the filing date of this Quarterly Report. We do not expect to generate any revenues from product sales unless and until we successfully complete development and obtain regulatory approval for one or more of our product candidates, which we expect will take a number of years at a minimum. If we obtain regulatory approval for any of our product candidates, we expect to incur significant commercialization expenses related to product sales, marketing, manufacturing and distribution. Accordingly, we will need to raise substantial additional capital beyond the net proceeds from our initial public offering (IPO). The amount and timing of our future funding requirements will depend on many factors, including the pace and results of our preclinical and clinical development efforts and the timing and nature of the regulatory approval process for our product candidates. We anticipate that we will seek to fund our operations through public or private equity or debt financings, collaborations, strategic partnerships or other sources. However, we may be unable to raise additional capital or enter into such other arrangements when needed on favorable terms or at all. Our failure to raise capital or enter into such other arrangements when needed would have a negative impact on our financial condition and ability to develop our product candidates. Use of Estimates Our consolidated financial statements are prepared in accordance with GAAP. The preparation of our consolidated financial statements requires us to make estimates and assumptions that impact the reported amounts of assets, liabilities and expenses and the disclosure of contingent assets and liabilities in our consolidated financial statements and accompanying notes. The most significant estimates in our consolidated financial statements relate to the fair value of equity issuances and awards, and clinical trials and research and development expense accruals. Although these estimates are based on our knowledge of current events and actions we may undertake in the future, actual results may ultimately differ materially from these estimates and assumptions. Net Loss Per Share Basic net loss per share is calculated by dividing the net loss by the weighted average number of common shares outstanding for the period, without consideration for common stock equivalents and adjusted for the weighted average number of common shares outstanding that are subject to repurchase. We have excluded 9,039 and 44,136 shares subject to repurchase from the weighted average number of common shares outstanding for the three months ended March 31, 2017 and 2016, respectively. Diluted net loss per share is calculated by dividing the net loss by the weighted average number of common stock equivalents outstanding for the period determined using the treasury-stock method. Dilutive common stock equivalents are comprised of warrants for common stock, restricted stock units and options outstanding under our stock option plan and employee stock purchase plan. For all periods presented, there is no difference in the number of shares used to calculate basic and diluted shares outstanding due to our net loss position. Potentially dilutive securities not included in the calculation of diluted net loss per share because to do so would be anti-dilutive are as follows (in common share equivalents): March 31, 2017 2016 Warrants for common stock 121,512 25,970 Common stock options and awards 4,720,382 3,742,770 Employee stock purchase plan 36,837 17,363 4,878,731 3,786,103 Recent Accounting Pronouncements In January 2016, the FASB issued ASU No. 2016-01, Financial Instruments-Overall: Recognition and Measurement of Financial Assets and Financial Liabilities In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) In June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments To achieve this objective, the amendments in this Update replace the incurred loss impairment methodology in current GAAP with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. |
Fair Value Measurements
Fair Value Measurements | 3 Months Ended |
Mar. 31, 2017 | |
Fair Value Disclosures [Abstract] | |
Fair Value Measurements | 2. Fair Value Measurements The carrying amounts of cash equivalents, prepaid and other assets, 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 currently available to us for loans with similar terms, which is considered a Level 2 input, we believe that the carrying value of our Term Loan approximates its fair value. Investment securities are recorded at fair value. The accounting guidance 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 defined as 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, the accounting guidance establishes a three-tier fair value hierarchy, which prioritizes the inputs used in measuring fair value as follows: Level 1: Observable inputs such as quoted prices in active markets. Level 2: Inputs, other than the quoted prices in active markets that are observable either directly or indirectly. Level 3: Unobservable inputs in which there is little or no market data, which require the reporting entity to develop its own assumptions. Financial assets measured at fair value on a recurring basis consist of investment securities. Investment securities are recorded at fair value, defined as the exit price in the principal market in which we would transact, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. Level 2 securities are valued using quoted market prices for similar instruments, non-binding market prices that are corroborated by observable market data, or discounted cash flow techniques and include our investments in corporate debt securities and commercial paper. We have no financial liabilities measured at fair value on a recurring basis. None of our non-financial assets and liabilities is recorded at fair value on a non-recurring basis. No transfers between levels have occurred during the periods presented. Assets measured at fair value on a recurring basis are as follows (in thousands): Fair Value Measurements Using Quoted Active for Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) As of March 31, 2017: Assets: Current: Cash equivalents $ 24,125 $ 24,125 $ — $ — Available-for-sale investments, short-term: Asset-backed securities 7,854 — 7,854 — Commercial paper 6,513 — 6,513 — Corporate debt securities 16,667 — 16,667 — United States Treasury securities 2,000 2,000 — — Sub-total short-term investments 33,034 2,000 31,034 - Total assets measured at fair value $ 57,159 $ 26,125 $ 31,034 $ — As of December 31, 2016: Assets: Current: Cash equivalents $ 29,251 $ 29,251 $ — $ — Available-for-sale investments, short-term: Commercial paper 7,843 — 7,843 — Corporate debt securities 20,913 — 20,913 — United States Treasury securities 5,003 5,003 — — Sub-total short-term investments 33,759 5,003 28,756 — Available-for-sale investments, long-term: Asset-backed securities 4,002 — 4,002 — Sub-total long-term investments 4,002 — 4,002 — Total assets measured at fair value $ 67,012 $ 34,254 $ 32,758 $ — As of March 31, 2017 and December 31, 2016 available-for-sale investments are detailed as follows (in thousands): March 31, 2017 Gross Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Market Value Available-for-sale investments, short-term: Asset-backed securities 7,857 — (3 ) 7,854 Commercial paper $ 6,513 $ — $ — $ 6,513 Corporate debt securities 16,683 — (16 ) 16,667 United States Treasury securities 2,001 — (1 ) 2,000 $ 33,054 $ — $ (20 ) $ 33,034 December 31, 2016 Gross Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Market Value Available-for-sale investments, short-term: Commercial paper $ 7,843 $ — $ — $ 7,843 Corporate debt securities 20,942 — (29 ) 20,913 United States Treasury securities 5,002 1 — 5,003 $ 33,787 $ 1 $ (29 ) $ 33,759 Available-for-sale investments, long-term: Asset-backed securities $ 4,001 $ 1 $ — $ 4,002 $ 4,001 $ 1 $ — $ 4,002 Available-for-sale investments that are in an unrealized loss position as of March 31, 2017 are as follows (in thousands): Estimated Fair Value Gross Unrealized Losses Asset-backed securities $ 7,854 $ (3 ) Corporate debt securities 16,667 $ (16 ) United States Treasury securities 2,000 $ (1 ) $ 26,521 $ (20 ) As of March 31, 2017, all of our available-for-sale investments have a variety of effective maturity dates of less than one year. As of March 31, 2017, there are 15 available-for-sale investments in gross unrealized loss position, all of which had been in such position for less than twelve months. At each reporting date, we perform an evaluation of impairment to determine if the unrealized losses are other-than-temporary. 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 of the issuer, and our intent and ability to hold the investment until recovery of its amortized cost basis. We intend, and have the ability, to hold our investments in unrealized loss positions until their amortized cost basis has been recovered. Based on our evaluation, we determined that the unrealized losses were not other-than-temporary as of March 31, 2017. |
Debt, Commitments and Contingen
Debt, Commitments and Contingencies | 3 Months Ended |
Mar. 31, 2017 | |
Debt Instruments [Abstract] | |
Debt, Commitments and Contingencies | 3. Debt, Commitments and Contingencies Term Loan In November 2016, we entered into a loan and security agreement with Silicon Valley Bank (SVB) and Solar Capital Ltd. (Solar), which we refer to as the Term Loan. SVB and Solar agreed to lend us up to $20.0 million, issuable in three separate tranches of: (i) $10.0 million which was funded on November 18, 2016; (ii) $5.0 million may be drawn down by us at any time before the earlier of June 30, 2017 or an event of default, at our discretion, subject to achievement of certain financial and clinical milestones; and (iii) $5.0 million may be drawn down by us any time after June 30, 2017 and before the earlier of December 31, 2017 or an event of default, at our discretion, subject to achievement of certain milestones specified for the second tranche and additional financial and clinical milestones. Pursuant to the Term Loan agreement, we have interest only payments through December 1, 2017 or June 1, 2018, if we draw the second tranche, followed by consecutive equal monthly payments of principal and interest in arrears through the maturity date of November 18, 2020. The Term Loan bears interest at the prime rate, as reported in The Wall Street Journal on the last date of the month preceding the month in which interest will accrue, plus 4.10%. The Term Loan also provides for a final payment equal to 8.75% of the funded amount, which is due when the Term Loan becomes due or upon the prepayment of the Term Loan. We have the option to prepay the outstanding balance of the loan in full, subject to a prepayment fee ranging from 1.0% to 3.0% depending upon when the prepayment occurs, including any non-usage fees. The loan agreement provides for a 2.0% non-usage fee for any unfunded amount in the event we do not draw the second tranche and third tranche, payable no later than the expiration date for the second tranche or third tranche, as applicable, or the date of cancellation of the loan due to prepayment or an event of default. No such events have occurred or are anticipated as of March 31, 2017. We received cash proceeds of $7.3 million, net of a $2.6 million repayment of the principal, accrued interest and the $0.5 million final payment under our previous $10.0 million loan and security agreement with SVB, which we refer to as the SVB Loan. We did not pay any termination or other fees in connection with the repayment of amounts due under the SVB Loan. As of March 31, 2017, the carrying value of our Term Loan consists of $10.0 million principal outstanding less the debt issuance costs of $0.4 million. The debt issuance costs have been recorded as a debt discount of long-term debt in our balance sheet, which are being accreted to interest expense over the life of the Term Loan using an effective interest rate of 12.28%. The final maturity payment of $0.9 million is being accrued over the life of the Term Loan through interest expense. Future principal payments for the Term Loan, including the final payment, are as follows (in thousands): March 31, 2017 2017 $ 248 2018 3,093 2019 3,348 2020 4,186 $ 10,875 Facility Lease In December 2011, we entered into a noncancelable operating lease that included certain tenant improvement allowances and is subject to base lease payments, which escalate over the term of the lease, additional charges for common area maintenance and other costs. In January 2017, we extended the lease for two years to May 2019. Rent expense for the three months ended March 31, 2017 and 2016 was $0.2 million and $0.1 million, respectively. In June 2016, we entered into a sublease agreement with a tenant of our landlord for additional facility space in our existing building that commenced in August 2016 and will expire in June 2017. Future minimum payments under the non-cancelable operating lease as of March 31, 2017 were as follows (in thousands): Operating Lease 2017 $ 683 2018 773 2019 293 $ 1,749 Research Agreements and Funding Obligations We provide funding to The Scripps Research Institute (TSRI) pursuant to a research funding and option agreement to conduct certain research activities. We have entered into additional amendments to our research funding and option agreement in 2017 to provide additional funding to TSRI through March 31, 2017. For the three months ended March 31, 2017 and 2016, the additional funding provided to TSRI was $0.2 million and $0.2 million, respectively. A member of our board of directors is a faculty member at TSRI and such payments fund a portion of his research activities conducted at TSRI. During the three months ended March 31, 2017 and 2016, we provided charitable donations to the National Foundation for Cancer Research of $0.1 million and $0.1 million, respectively. We have requested that the donations be restricted to certain basic research in cancer biology and therapeutics, a portion of which funds research activities conducted at TSRI in the laboratory of a member of our board of directors. |
Stockholders' Equity
Stockholders' Equity | 3 Months Ended |
Mar. 31, 2017 | |
Equity [Abstract] | |
Stockholders' Equity | 4. Stockholders’ Equity Common Stock Reserved for Future Issuance Pursuant to the automatic increase provisions of our 2015 Stock Option and Incentive Plan (2015 Plan) and 2015 Employee Stock Purchase Plan (2015 ESPP), 949,793 additional shares were reserved for future issuance under the 2015 Plan on January 1, 2017 and 237,448 additional shares were reserved for future issuances under the 2015 ESPP on January 1, 2017. Common stock reserved for future issuance is as follows: March 31, 2017 Common stock warrants 121,512 Common stock options and awards outstanding 4,720,382 Shares available under the 2015 Plan 795,728 Shares available under the 2015 ESPP 644,990 6,282,612 The following table summarizes our stock option activity under all equity incentive plans for the three months ended March 31, 2017: Number of Outstanding Options Weighted Average Exercise Price Outstanding as of December 31, 2016 4,014,988 $ 6.73 Granted 765,719 $ 3.29 Exercised (795 ) $ 1.01 Canceled/forfeited/expired (122,894 ) $ 6.98 Outstanding as of March 31, 2017 4,657,018 $ 6.16 The assumptions used in the Black-Scholes option pricing model to determine the fair value of the employee stock option grants were as follows: Three Months Ended March 31, 2017 2016 Expected term (in years) 6.02 – 6.06 5.77 – 6.08 Risk-free interest rate 2.0% – 2.1% 1.4% – 1.9% Expected volatility 104.0% – 105.2% 81.2% – 82.1% Expected dividend yield 0.0% 0.0% The following table summarizes our restricted stock unit activity under all equity incentive plans for the three months ended March 31, 2017: Number of Outstanding Restricted Stock Units Weighted Average Grant Date Fair Value Balance as of December 31, 2016 76,713 $ 4.95 Granted 22,000 $ 3.30 Released (35,349 ) $ 5.00 Forfeited — $ — Balance as of March 31, 2017 63,364 $ 4.35 Stock-based Compensation The allocation of stock-based compensation for all options, including performance options with a market condition, 2015 ESPP and restricted stock units is as follows (in thousands): Three Months Ended March 31, 2017 2016 Research and development $ 444 $ 547 General and administrative 833 733 $ 1,277 $ 1,280 |
Subsequent Events
Subsequent Events | 3 Months Ended |
Mar. 31, 2017 | |
Subsequent Events [Abstract] | |
Subsequent Events | 5. Subsequent Events In April 2017, we amended our facility lease to include an additional 7,411 square feet through May 2019 for a total additional commitment of $0.7 million. |
Organization, Business, Basis12
Organization, Business, Basis of Presentation and Summary of Significant Accounting Policies (Policies) | 3 Months Ended |
Mar. 31, 2017 | |
Accounting Policies [Abstract] | |
Organization and Business | Organization and Business aTyr Pharma, Inc. (we, us, and our) was incorporated in the state of Delaware on September 8, 2005. We are focused on the discovery and clinical development of innovative medicines for patients suffering from severe rare diseases. |
Principles of Consolidation | Principles of Consolidation Our consolidated financial statements include our accounts and our 98% majority-owned subsidiary in Hong Kong, Pangu BioPharma Limited (Pangu BioPharma). All intercompany transactions and balances are eliminated in consolidation. |
Unaudited Interim Financial Information | Unaudited Interim Financial Information The accompanying interim condensed consolidated financial statements are unaudited. These unaudited interim financial statements have been prepared in accordance with United States generally accepted accounting principles (GAAP) and following the requirements of the United States Securities and Exchange Commission (SEC) for interim reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by GAAP can be condensed or omitted. In our opinion, the unaudited interim financial statements have been prepared on the same basis as the audited financial statements and include all adjustments, which include only normal recurring adjustments, necessary for the fair presentation of our financial position and our results of operations and cash flows for periods presented. These statements do not include all disclosures required by GAAP and should be read in conjunction with our financial statements and accompanying notes for the fiscal year ended December 31, 2016, contained in our Annual Report on Form 10-K filed with the SEC on March 16, 2017. The results of the interim periods are not necessarily indicative of the results expected for the full fiscal year or any other interim period or any future year or period. |
Liquidity and Financial Condition | Liquidity and Financial Condition We have incurred losses and negative cash flows from operations since our inception. As of March 31, 2017, we had an accumulated deficit of $229.4 million and we expect to continue to incur net losses for the foreseeable future. We believe that our existing cash, cash equivalents and available-for-sale investments, of $61.9 million as of March 31, 2017 will be sufficient to meet our anticipated cash requirements for a period of one year from the filing date of this Quarterly Report. We do not expect to generate any revenues from product sales unless and until we successfully complete development and obtain regulatory approval for one or more of our product candidates, which we expect will take a number of years at a minimum. If we obtain regulatory approval for any of our product candidates, we expect to incur significant commercialization expenses related to product sales, marketing, manufacturing and distribution. Accordingly, we will need to raise substantial additional capital beyond the net proceeds from our initial public offering (IPO). The amount and timing of our future funding requirements will depend on many factors, including the pace and results of our preclinical and clinical development efforts and the timing and nature of the regulatory approval process for our product candidates. We anticipate that we will seek to fund our operations through public or private equity or debt financings, collaborations, strategic partnerships or other sources. However, we may be unable to raise additional capital or enter into such other arrangements when needed on favorable terms or at all. Our failure to raise capital or enter into such other arrangements when needed would have a negative impact on our financial condition and ability to develop our product candidates. |
Use of Estimates | Use of Estimates Our consolidated financial statements are prepared in accordance with GAAP. The preparation of our consolidated financial statements requires us to make estimates and assumptions that impact the reported amounts of assets, liabilities and expenses and the disclosure of contingent assets and liabilities in our consolidated financial statements and accompanying notes. The most significant estimates in our consolidated financial statements relate to the fair value of equity issuances and awards, and clinical trials and research and development expense accruals. Although these estimates are based on our knowledge of current events and actions we may undertake in the future, actual results may ultimately differ materially from these estimates and assumptions. |
Net Loss Per Share | Net Loss Per Share Basic net loss per share is calculated by dividing the net loss by the weighted average number of common shares outstanding for the period, without consideration for common stock equivalents and adjusted for the weighted average number of common shares outstanding that are subject to repurchase. We have excluded 9,039 and 44,136 shares subject to repurchase from the weighted average number of common shares outstanding for the three months ended March 31, 2017 and 2016, respectively. Diluted net loss per share is calculated by dividing the net loss by the weighted average number of common stock equivalents outstanding for the period determined using the treasury-stock method. Dilutive common stock equivalents are comprised of warrants for common stock, restricted stock units and options outstanding under our stock option plan and employee stock purchase plan. For all periods presented, there is no difference in the number of shares used to calculate basic and diluted shares outstanding due to our net loss position. Potentially dilutive securities not included in the calculation of diluted net loss per share because to do so would be anti-dilutive are as follows (in common share equivalents): March 31, 2017 2016 Warrants for common stock 121,512 25,970 Common stock options and awards 4,720,382 3,742,770 Employee stock purchase plan 36,837 17,363 4,878,731 3,786,103 |
Recent Accounting Pronouncements | Recent Accounting Pronouncements In January 2016, the FASB issued ASU No. 2016-01, Financial Instruments-Overall: Recognition and Measurement of Financial Assets and Financial Liabilities In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) In June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments To achieve this objective, the amendments in this Update replace the incurred loss impairment methodology in current GAAP with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. |
Organization, Business, Basis13
Organization, Business, Basis of Presentation and Summary of Significant Accounting Policies (Tables) | 3 Months Ended |
Mar. 31, 2017 | |
Accounting Policies [Abstract] | |
Schedule of Potentially Dilutive Securities Not Included in Calculation of Diluted Net Loss Per Share | Potentially dilutive securities not included in the calculation of diluted net loss per share because to do so would be anti-dilutive are as follows (in common share equivalents): March 31, 2017 2016 Warrants for common stock 121,512 25,970 Common stock options and awards 4,720,382 3,742,770 Employee stock purchase plan 36,837 17,363 4,878,731 3,786,103 |
Fair Value Measurements (Tables
Fair Value Measurements (Tables) | 3 Months Ended |
Mar. 31, 2017 | |
Fair Value Disclosures [Abstract] | |
Schedule of Assets Measured at Fair Value on Recurring Basis | Assets measured at fair value on a recurring basis are as follows (in thousands): Fair Value Measurements Using Quoted Active for Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) As of March 31, 2017: Assets: Current: Cash equivalents $ 24,125 $ 24,125 $ — $ — Available-for-sale investments, short-term: Asset-backed securities 7,854 — 7,854 — Commercial paper 6,513 — 6,513 — Corporate debt securities 16,667 — 16,667 — United States Treasury securities 2,000 2,000 — — Sub-total short-term investments 33,034 2,000 31,034 - Total assets measured at fair value $ 57,159 $ 26,125 $ 31,034 $ — As of December 31, 2016: Assets: Current: Cash equivalents $ 29,251 $ 29,251 $ — $ — Available-for-sale investments, short-term: Commercial paper 7,843 — 7,843 — Corporate debt securities 20,913 — 20,913 — United States Treasury securities 5,003 5,003 — — Sub-total short-term investments 33,759 5,003 28,756 — Available-for-sale investments, long-term: Asset-backed securities 4,002 — 4,002 — Sub-total long-term investments 4,002 — 4,002 — Total assets measured at fair value $ 67,012 $ 34,254 $ 32,758 $ — |
Schedule of Available-for-sale Investments | As of March 31, 2017 and December 31, 2016 available-for-sale investments are detailed as follows (in thousands): March 31, 2017 Gross Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Market Value Available-for-sale investments, short-term: Asset-backed securities 7,857 — (3 ) 7,854 Commercial paper $ 6,513 $ — $ — $ 6,513 Corporate debt securities 16,683 — (16 ) 16,667 United States Treasury securities 2,001 — (1 ) 2,000 $ 33,054 $ — $ (20 ) $ 33,034 December 31, 2016 Gross Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Market Value Available-for-sale investments, short-term: Commercial paper $ 7,843 $ — $ — $ 7,843 Corporate debt securities 20,942 — (29 ) 20,913 United States Treasury securities 5,002 1 — 5,003 $ 33,787 $ 1 $ (29 ) $ 33,759 Available-for-sale investments, long-term: Asset-backed securities $ 4,001 $ 1 $ — $ 4,002 $ 4,001 $ 1 $ — $ 4,002 |
Schedule of Available-for-sale Investments in Unrealized Loss Position | Available-for-sale investments that are in an unrealized loss position as of March 31, 2017 are as follows (in thousands): Estimated Fair Value Gross Unrealized Losses Asset-backed securities $ 7,854 $ (3 ) Corporate debt securities 16,667 $ (16 ) United States Treasury securities 2,000 $ (1 ) $ 26,521 $ (20 ) |
Debt, Commitments and Conting15
Debt, Commitments and Contingencies (Tables) | 3 Months Ended |
Mar. 31, 2017 | |
Debt Instruments [Abstract] | |
Schedule of Future Principal Payments for Term Loan Including Final Payment | Future principal payments for the Term Loan, including the final payment, are as follows (in thousands): March 31, 2017 2017 $ 248 2018 3,093 2019 3,348 2020 4,186 $ 10,875 |
Schedule of Future Minimum Payments under Non-cancelable Operating Lease | Future minimum payments under the non-cancelable operating lease as of March 31, 2017 were as follows (in thousands): Operating Lease 2017 $ 683 2018 773 2019 293 $ 1,749 |
Stockholders' Equity (Tables)
Stockholders' Equity (Tables) | 3 Months Ended |
Mar. 31, 2017 | |
Summary of Common Stock Reserved for Future Issuance | Common stock reserved for future issuance is as follows: March 31, 2017 Common stock warrants 121,512 Common stock options and awards outstanding 4,720,382 Shares available under the 2015 Plan 795,728 Shares available under the 2015 ESPP 644,990 6,282,612 |
Summary of Stock Option Activity | The following table summarizes our stock option activity under all equity incentive plans for the three months ended March 31, 2017: Number of Outstanding Options Weighted Average Exercise Price Outstanding as of December 31, 2016 4,014,988 $ 6.73 Granted 765,719 $ 3.29 Exercised (795 ) $ 1.01 Canceled/forfeited/expired (122,894 ) $ 6.98 Outstanding as of March 31, 2017 4,657,018 $ 6.16 |
Schedule of Restricted Stock Unit Activity | The following table summarizes our restricted stock unit activity under all equity incentive plans for the three months ended March 31, 2017: Number of Outstanding Restricted Stock Units Weighted Average Grant Date Fair Value Balance as of December 31, 2016 76,713 $ 4.95 Granted 22,000 $ 3.30 Released (35,349 ) $ 5.00 Forfeited — $ — Balance as of March 31, 2017 63,364 $ 4.35 |
Schedule of Allocation of Stock-Based Compensation for All Options Including Performance Options with Market Condition, 2015 ESPP and Restricted Stock Units | The allocation of stock-based compensation for all options, including performance options with a market condition, 2015 ESPP and restricted stock units is as follows (in thousands): Three Months Ended March 31, 2017 2016 Research and development $ 444 $ 547 General and administrative 833 733 $ 1,277 $ 1,280 |
Employee Stock Option [Member] | |
Summary of Assumptions Used to Determine Fair Value of Employee Stock Option Grants | The assumptions used in the Black-Scholes option pricing model to determine the fair value of the employee stock option grants were as follows: Three Months Ended March 31, 2017 2016 Expected term (in years) 6.02 – 6.06 5.77 – 6.08 Risk-free interest rate 2.0% – 2.1% 1.4% – 1.9% Expected volatility 104.0% – 105.2% 81.2% – 82.1% Expected dividend yield 0.0% 0.0% |
Organization, Business, Basis17
Organization, Business, Basis of Presentation and Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($) $ in Thousands | 3 Months Ended | ||
Mar. 31, 2017 | Mar. 31, 2016 | Dec. 31, 2016 | |
Significant Accounting Policies [Line Items] | |||
Accumulated deficit | $ 229,384 | $ 215,979 | |
Cash, cash equivalents and available-for-sale investments | $ 61,900 | ||
Weighted average shares subject to repurchase | 9,039 | 44,136 | |
Pangu BioPharma [Member] | Hong Kong [Member] | |||
Significant Accounting Policies [Line Items] | |||
Majority-owned subsidiary percentage | 98.00% |
Organization, Business, Basis18
Organization, Business, Basis of Presentation and Summary of Significant Accounting Policies - Schedule of Potentially Dilutive Securities Not Included in Calculation of Diluted Net Loss Per Share (Detail) - shares | 3 Months Ended | |
Mar. 31, 2017 | Mar. 31, 2016 | |
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] | ||
Anti-dilutive securities not included in calculation of diluted net loss per share | 4,878,731 | 3,786,103 |
Warrants for Common Stock [Member] | ||
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] | ||
Anti-dilutive securities not included in calculation of diluted net loss per share | 121,512 | 25,970 |
Common Stock Options and Awards [Member] | ||
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] | ||
Anti-dilutive securities not included in calculation of diluted net loss per share | 4,720,382 | 3,742,770 |
Employee Stock Purchase Plan [Member] | ||
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] | ||
Anti-dilutive securities not included in calculation of diluted net loss per share | 36,837 | 17,363 |
Fair Value Measurements - Sched
Fair Value Measurements - Schedule of Assets Measured at Fair Value on Recurring Basis (Detail) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands | Mar. 31, 2017 | Dec. 31, 2016 |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
Cash equivalents | $ 24,125 | $ 29,251 |
Total assets measured at fair value | 57,159 | 67,012 |
Available-for-sale [Member] | Short-term Investments [Member] | ||
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
Investments, fair value | 33,034 | 33,759 |
Available-for-sale [Member] | Short-term Investments [Member] | Commercial Paper [Member] | ||
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
Investments, fair value | 6,513 | 7,843 |
Available-for-sale [Member] | Short-term Investments [Member] | United States Treasury Securities [Member] | ||
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
Investments, fair value | 2,000 | 5,003 |
Available-for-sale [Member] | Short-term Investments [Member] | Corporate Debt Securities [Member] | ||
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
Investments, fair value | 16,667 | 20,913 |
Available-for-sale [Member] | Short-term Investments [Member] | Asset-backed Securities [Member] | ||
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
Investments, fair value | 7,854 | |
Available-for-sale [Member] | Long-term Investments [Member] | ||
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
Investments, fair value | 4,002 | |
Available-for-sale [Member] | Long-term Investments [Member] | Asset-backed Securities [Member] | ||
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
Investments, fair value | 4,002 | |
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | ||
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
Cash equivalents | 24,125 | 29,251 |
Total assets measured at fair value | 26,125 | 34,254 |
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Available-for-sale [Member] | Short-term Investments [Member] | ||
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
Investments, fair value | 2,000 | 5,003 |
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Available-for-sale [Member] | Short-term Investments [Member] | United States Treasury Securities [Member] | ||
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
Investments, fair value | 2,000 | 5,003 |
Significant Other Observable Inputs (Level 2) [Member] | ||
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
Total assets measured at fair value | 31,034 | 32,758 |
Significant Other Observable Inputs (Level 2) [Member] | Available-for-sale [Member] | Short-term Investments [Member] | ||
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
Investments, fair value | 31,034 | 28,756 |
Significant Other Observable Inputs (Level 2) [Member] | Available-for-sale [Member] | Short-term Investments [Member] | Commercial Paper [Member] | ||
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
Investments, fair value | 6,513 | 7,843 |
Significant Other Observable Inputs (Level 2) [Member] | Available-for-sale [Member] | Short-term Investments [Member] | Corporate Debt Securities [Member] | ||
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
Investments, fair value | 16,667 | 20,913 |
Significant Other Observable Inputs (Level 2) [Member] | Available-for-sale [Member] | Short-term Investments [Member] | Asset-backed Securities [Member] | ||
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
Investments, fair value | $ 7,854 | |
Significant Other Observable Inputs (Level 2) [Member] | Available-for-sale [Member] | Long-term Investments [Member] | ||
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
Investments, fair value | 4,002 | |
Significant Other Observable Inputs (Level 2) [Member] | Available-for-sale [Member] | Long-term Investments [Member] | Asset-backed Securities [Member] | ||
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | ||
Investments, fair value | $ 4,002 |
Fair Value Measurements - Sch20
Fair Value Measurements - Schedule of Available-for-sale Investments (Detail) - USD ($) $ in Thousands | Mar. 31, 2017 | Dec. 31, 2016 |
Short-term Investments [Member] | ||
Schedule of Available-for-sale Securities [Line Items] | ||
Gross Amortized Cost | $ 33,054 | $ 33,787 |
Gross Unrealized Gains | 1 | |
Gross Unrealized Losses | (20) | (29) |
Market Value | 33,034 | 33,759 |
Short-term Investments [Member] | Commercial Paper [Member] | ||
Schedule of Available-for-sale Securities [Line Items] | ||
Gross Amortized Cost | 6,513 | 7,843 |
Market Value | 6,513 | 7,843 |
Short-term Investments [Member] | United States Treasury Securities [Member] | ||
Schedule of Available-for-sale Securities [Line Items] | ||
Gross Amortized Cost | 2,001 | 5,002 |
Gross Unrealized Gains | 1 | |
Gross Unrealized Losses | (1) | |
Market Value | 2,000 | 5,003 |
Short-term Investments [Member] | Corporate Debt Securities [Member] | ||
Schedule of Available-for-sale Securities [Line Items] | ||
Gross Amortized Cost | 16,683 | 20,942 |
Gross Unrealized Losses | (16) | (29) |
Market Value | 16,667 | 20,913 |
Short-term Investments [Member] | Asset-backed Securities [Member] | ||
Schedule of Available-for-sale Securities [Line Items] | ||
Gross Amortized Cost | 7,857 | |
Gross Unrealized Losses | (3) | |
Market Value | $ 7,854 | |
Long-term Investments [Member] | ||
Schedule of Available-for-sale Securities [Line Items] | ||
Gross Amortized Cost | 4,001 | |
Gross Unrealized Gains | 1 | |
Market Value | 4,002 | |
Long-term Investments [Member] | Asset-backed Securities [Member] | ||
Schedule of Available-for-sale Securities [Line Items] | ||
Gross Amortized Cost | 4,001 | |
Gross Unrealized Gains | 1 | |
Market Value | $ 4,002 |
Fair Value Measurements - Sch21
Fair Value Measurements - Schedule of Available-for-sale Investments in Unrealized Loss Position (Detail) $ in Thousands | Mar. 31, 2017USD ($) |
Schedule of Available-for-sale Securities [Line Items] | |
Estimated Fair Value | $ 26,521 |
Gross Unrealized Losses | (20) |
Asset-backed Securities [Member] | |
Schedule of Available-for-sale Securities [Line Items] | |
Estimated Fair Value | 7,854 |
Gross Unrealized Losses | (3) |
Corporate Debt Securities [Member] | |
Schedule of Available-for-sale Securities [Line Items] | |
Estimated Fair Value | 16,667 |
Gross Unrealized Losses | (16) |
United States Treasury Securities [Member] | |
Schedule of Available-for-sale Securities [Line Items] | |
Estimated Fair Value | 2,000 |
Gross Unrealized Losses | $ (1) |
Fair Value Measurements - Addit
Fair Value Measurements - Additional Information (Detail) | 3 Months Ended |
Mar. 31, 2017Security | |
Schedule of Available-for-sale Securities [Line Items] | |
Available-for-sale investments in gross unrealized loss position | 15 |
Available-for-sale investments in gross unrealized loss position | 12 months |
Maximum [Member] | |
Schedule of Available-for-sale Securities [Line Items] | |
Available-for-sale investments effective maturity period | 1 year |
Debt, Commitments and Conting23
Debt, Commitments and Contingencies - Additional Information (Detail) | 1 Months Ended | 3 Months Ended | ||||||
Jan. 31, 2017 | Nov. 30, 2016USD ($)Tranche | Jun. 30, 2016 | Mar. 31, 2017USD ($) | Mar. 31, 2016USD ($) | Dec. 31, 2017USD ($) | Jun. 30, 2017USD ($) | Nov. 18, 2016USD ($) | |
Debt Instrument [Line Items] | ||||||||
Loan and security agreement, payment term | (i) $10.0 million which was funded on November 18, 2016; (ii) $5.0 million may be drawn down by us at any time before the earlier of June 30, 2017 or an event of default, at our discretion, subject to achievement of certain financial and clinical milestones; and (iii) $5.0 million may be drawn down by us any time after June 30, 2017 and before the earlier of December 31, 2017 or an event of default, at our discretion, subject to achievement of certain milestones specified for the second tranche and additional financial and clinical milestones. | |||||||
Extended term of lease | 2 years | |||||||
Noncancelable operating lease extension period | 2019-05 | |||||||
Rent expense | $ 200,000 | $ 100,000 | ||||||
Sublease agreement, additional facility space, commenced period | 2016-08 | |||||||
Sublease agreement, additional facility space, expiration period | 2017-06 | |||||||
Research Funding and Option Agreement [Member] | The Scripps Research Institute [Member] | ||||||||
Debt Instrument [Line Items] | ||||||||
Additional funding for research conducted | 200,000 | 200,000 | ||||||
Research Funding and Option Agreement [Member] | National Foundation for Cancer Research [Member] | ||||||||
Debt Instrument [Line Items] | ||||||||
Charitable donations | 100,000 | $ 100,000 | ||||||
Silicon Valley Bank and Solar Capital, Ltd. [Member] | ||||||||
Debt Instrument [Line Items] | ||||||||
Available credit under loan and security agreement | $ 20,000,000 | $ 10,000,000 | ||||||
Number of tranches | Tranche | 3 | |||||||
Loan and security agreement, payment term | Pursuant to the Term Loan agreement, we have interest only payments through December 1, 2017 or June 1, 2018, if we draw the second tranche, followed by consecutive equal monthly payments of principal and interest in arrears through the maturity date of November 18, 2020. | |||||||
Maturity date | Nov. 18, 2020 | |||||||
Percentage of funded amount for final payment | 8.75% | |||||||
Non-usage fee percentage | 2.00% | |||||||
Net cash proceeds from borrowings | $ 7,300,000 | |||||||
Repayment of debt, principal including accrued interest | 2,600,000 | |||||||
Debt instrument, final payment | $ 500,000 | |||||||
Term loan effective interest rate | 12.28% | |||||||
Term loan, principal outstanding before deducting debt issuance cost | $ 10,000,000 | |||||||
Term loan, debt issuance costs | 400,000 | |||||||
Final maturity payment accrued over life of term loan through interest expense | $ 900,000 | |||||||
Silicon Valley Bank and Solar Capital, Ltd. [Member] | Prime Rate | ||||||||
Debt Instrument [Line Items] | ||||||||
Interest rate spread on variable rate | 4.10% | |||||||
Silicon Valley Bank and Solar Capital, Ltd. [Member] | Tranche One [Member] | ||||||||
Debt Instrument [Line Items] | ||||||||
Available credit under loan and security agreement | $ 10,000,000 | |||||||
Loan and security agreement funded date | Nov. 18, 2016 | |||||||
Silicon Valley Bank and Solar Capital, Ltd. [Member] | Tranche Two [Member] | Scenario Forecast [ Member] | ||||||||
Debt Instrument [Line Items] | ||||||||
Available credit under loan and security agreement | $ 5,000,000 | |||||||
Silicon Valley Bank and Solar Capital, Ltd. [Member] | Tranche Three [Member] | Scenario Forecast [ Member] | ||||||||
Debt Instrument [Line Items] | ||||||||
Available credit under loan and security agreement | $ 5,000,000 | |||||||
Silicon Valley Bank and Solar Capital, Ltd. [Member] | Minimum [Member] | ||||||||
Debt Instrument [Line Items] | ||||||||
Prepayment fee percentage | 1.00% | |||||||
Silicon Valley Bank and Solar Capital, Ltd. [Member] | Minimum [Member] | Tranche Three [Member] | ||||||||
Debt Instrument [Line Items] | ||||||||
Loan and security agreement funded date | Jun. 30, 2017 | |||||||
Silicon Valley Bank and Solar Capital, Ltd. [Member] | Maximum [Member] | ||||||||
Debt Instrument [Line Items] | ||||||||
Prepayment fee percentage | 3.00% | |||||||
Silicon Valley Bank and Solar Capital, Ltd. [Member] | Maximum [Member] | Tranche Two [Member] | ||||||||
Debt Instrument [Line Items] | ||||||||
Loan and security agreement funded date | Jun. 30, 2017 | |||||||
Silicon Valley Bank and Solar Capital, Ltd. [Member] | Maximum [Member] | Tranche Three [Member] | ||||||||
Debt Instrument [Line Items] | ||||||||
Loan and security agreement funded date | Dec. 31, 2017 |
Debt, Commitments and Conting24
Debt, Commitments and Contingencies - Schedule of Future Principal Payments for Term Loan Including Final Payment (Detail) - Silicon Valley Bank and Solar Capital, Ltd. [Member] $ in Thousands | Mar. 31, 2017USD ($) |
Debt Instrument [Line Items] | |
2,017 | $ 248 |
2,018 | 3,093 |
2,019 | 3,348 |
2,020 | 4,186 |
Future principal payments for term loan including final payment, total | $ 10,875 |
Debt, Commitments and Conting25
Debt, Commitments and Contingencies - Schedule of Future Minimum Payments under Non-cancelable Operating Lease (Detail) $ in Thousands | Mar. 31, 2017USD ($) |
Leases Operating [Abstract] | |
2,017 | $ 683 |
2,018 | 773 |
2,019 | 293 |
Operating Lease, total | $ 1,749 |
Stockholders' Equity - Addition
Stockholders' Equity - Additional Information (Detail) | Jan. 01, 2017shares |
2015 Stock Option and Incentive Plan [Member] | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |
Additional number of common stock shares reserved for issuance | 949,793 |
2015 Employee Stock Purchase Plan [Member] | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |
Additional number of common stock shares reserved for issuance | 237,448 |
Stockholders' Equity - Summary
Stockholders' Equity - Summary of Common Stock Reserved for Future Issuance (Detail) | Mar. 31, 2017shares |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |
Common stock reserved for future issuance | 6,282,612 |
Common Stock Warrants [Member] | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |
Common stock reserved for future issuance | 121,512 |
Shares Available Under the 2015 Plan [Member] | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |
Common stock reserved for future issuance | 795,728 |
Shares Available Under the 2015 ESPP [Member] | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |
Common stock reserved for future issuance | 644,990 |
Common Stock Options and Awards [Member] | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | |
Common stock reserved for future issuance | 4,720,382 |
Stockholders' Equity - Summar28
Stockholders' Equity - Summary of Stock Option Activity (Detail) | 3 Months Ended |
Mar. 31, 2017$ / sharesshares | |
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract] | |
Number of Outstanding Options, Beginning Balance | shares | 4,014,988 |
Number of Options, Granted | shares | 765,719 |
Number of Options, Exercised | shares | (795) |
Number of Options, Canceled/forfeited/expired | shares | (122,894) |
Number of Outstanding Options, Ending Balance | shares | 4,657,018 |
Weighted Average Exercise Price, Beginning Balance | $ / shares | $ 6.73 |
Weighted Average Exercise Price, Granted | $ / shares | 3.29 |
Weighted Average Exercise Price, Exercised | $ / shares | 1.01 |
Weighted Average Exercise Price, Canceled/forfeited/expired | $ / shares | 6.98 |
Weighted Average Exercise Price, Ending Balance | $ / shares | $ 6.16 |
Stockholders' Equity - Summar29
Stockholders' Equity - Summary of Assumptions Used to Determine Fair Value of Employee Stock Option Grants (Detail) - Employee Stock Option [Member] | 3 Months Ended | |
Mar. 31, 2017 | Mar. 31, 2016 | |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||
Risk-free interest rate, minimum | 2.00% | 1.40% |
Risk-free interest rate, maximum | 2.10% | 1.90% |
Expected volatility, minimum | 104.00% | 81.20% |
Expected volatility, maximum | 105.20% | 82.10% |
Expected dividend yield | 0.00% | 0.00% |
Minimum [Member] | ||
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||
Expected term (in years) | 6 years 7 days | 5 years 9 months 7 days |
Maximum [Member] | ||
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||
Expected term (in years) | 6 years 22 days | 6 years 29 days |
Stockholders' Equity - Schedule
Stockholders' Equity - Schedule of Restricted Stock Unit Activity (Detail) - Restricted Stock Unit [Member] | 3 Months Ended |
Mar. 31, 2017$ / sharesshares | |
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items] | |
Number of Outstanding Restricted Stock Units, Beginning Balance | shares | 76,713 |
Number of Outstanding Restricted Stock Units, Granted | shares | 22,000 |
Number of Outstanding Restricted Stock Units, Released | shares | (35,349) |
Number of Outstanding Restricted Stock Units, Ending Balance | shares | 63,364 |
Weighted Average Grant Date Fair Value, Beginning Balance | $ / shares | $ 4.95 |
Weighted Average Grant Date Fair Value, Granted | $ / shares | 3.30 |
Weighted Average Grant Date Fair Value, Released | $ / shares | 5 |
Weighted Average Grant Date Fair Value, Ending Balance | $ / shares | $ 4.35 |
Stockholders' Equity - Schedu31
Stockholders' Equity - Schedule of Allocation of Stock-Based Compensation for All Options Including Performance Options with Market Condition, 2015 ESPP and Restricted Stock Units (Detail) - USD ($) $ in Thousands | 3 Months Ended | |
Mar. 31, 2017 | Mar. 31, 2016 | |
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items] | ||
Total stock-based compensation expense | $ 1,277 | $ 1,280 |
Research and Development Expense [Member] | ||
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items] | ||
Total stock-based compensation expense | 444 | 547 |
General and Administrative Expense [Member] | ||
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items] | ||
Total stock-based compensation expense | $ 833 | $ 733 |
Subsequent Events - Additional
Subsequent Events - Additional Information (Detail) $ in Millions | 1 Months Ended | 3 Months Ended |
Apr. 30, 2017USD ($)ft² | Mar. 31, 2017 | |
Subsequent Event [Line Items] | ||
Noncancelable operating lease extension period | 2019-05 | |
Subsequent Event [Member] | ||
Subsequent Event [Line Items] | ||
Additional lease facility | ft² | 7,411 | |
Noncancelable operating lease extension period | 2019-05 | |
Noncancelable operating lease total additional commitment | $ | $ 0.7 |