Document and Entity Information
Document and Entity Information - USD ($) $ in Millions | 12 Months Ended | ||
Dec. 31, 2017 | Feb. 28, 2018 | Jun. 30, 2017 | |
Document And Entity Information [Abstract] | |||
Document Type | 10-K | ||
Amendment Flag | false | ||
Document Period End Date | Dec. 31, 2017 | ||
Document Fiscal Year Focus | 2,017 | ||
Document Fiscal Period Focus | FY | ||
Entity Well-known Seasoned Issuer | No | ||
Entity Voluntary Filers | No | ||
Entity Current Reporting Status | Yes | ||
Trading Symbol | TOCA | ||
Entity Registrant Name | Tocagen Inc | ||
Entity Central Index Key | 1,419,041 | ||
Current Fiscal Year End Date | --12-31 | ||
Entity Filer Category | Non-accelerated Filer | ||
Entity Common Stock, Shares Outstanding | 19,911,616 | ||
Entity Public Float | $ 217 |
Balance Sheets
Balance Sheets - USD ($) $ in Thousands | Dec. 31, 2017 | Dec. 31, 2016 |
Current assets: | ||
Cash and cash equivalents | $ 35,933 | $ 5,510 |
Marketable securities | 52,792 | 25,735 |
Prepaid expenses and other current assets | 1,904 | 1,216 |
Total current assets | 90,629 | 32,461 |
Property and equipment, net | 1,217 | 743 |
Other assets | 227 | 2,147 |
Total assets | 92,073 | 35,351 |
Current liabilities: | ||
Accounts payable | 1,951 | 1,666 |
Accrued liabilities | 8,120 | 5,437 |
Notes payable, current portion | 7,200 | 7,200 |
Deferred license revenue | 36 | 45 |
Deferred grant funding | 23 | 34 |
Total current liabilities | 17,330 | 14,382 |
Notes payable, net of current portion | 3,625 | 10,241 |
Convertible promissory notes payable (due to related parties of $0 and $1,025 at December 31, 2017 and December 31, 2016, respectively) | 3,398 | |
Convertible promissory notes subscription liability | 140 | |
Long-term portion of deferred license revenue | 36 | 68 |
Preferred stock warrant liabilities | 126 | |
Total liabilities | 20,991 | 28,355 |
Commitments and contingencies | ||
Convertible preferred stock, $0.001 par value; 51,000,000 shares authorized at December 31, 2016; 46,163,605 shares issued and outstanding at December 31, 2016; aggregate liquidation preferences of $131,720 at December 31, 2016 | 131,413 | |
Stockholders’ equity (deficit): | ||
Preferred stock, $0.001 par value; 10,000,000 shares authorized at December 31, 2017; no shares issued or outstanding at December 31, 2017 | ||
Common stock, $0.001 par value; 200,000,000 and 77,800,000 shares authorized at December 31, 2017 and December 31, 2016, respectively; 19,882,551 and 2,202,517 shares issued and outstanding at December 31, 2017 and December 31, 2016, respectively | 20 | 2 |
Additional paid-in capital | 238,025 | 3,581 |
Accumulated deficit | (166,929) | (128,000) |
Accumulated other comprehensive loss | (34) | |
Total stockholders’ equity (deficit) | 71,082 | (124,417) |
Total liabilities, convertible preferred stock and stockholders’ equity (deficit) | $ 92,073 | $ 35,351 |
Balance Sheets (Parenthetical)
Balance Sheets (Parenthetical) - USD ($) $ in Thousands | Dec. 31, 2017 | Dec. 31, 2016 |
Statement Of Financial Position [Abstract] | ||
Due to related parties | $ 0 | $ 1,025 |
Convertible preferred stock, par value | $ 0.001 | |
Convertible preferred stock, shares authorized | 51,000,000 | |
Convertible preferred stock, shares issued | 46,163,605 | |
Convertible preferred stock, shares outstanding | 46,163,605 | |
Convertible preferred stock, liquidation preference | $ 131,720 | |
Preferred stock, par value | $ 0.001 | |
Preferred stock, shares authorized | 10,000,000 | |
Preferred stock, shares issued | 0 | |
Preferred stock, shares outstanding | 0 | |
Common stock, par value | $ 0.001 | $ 0.001 |
Common stock, shares authorized | 200,000,000 | 77,800,000 |
Common stock, shares issued | 19,882,551 | 2,202,517 |
Common stock, shares outstanding | 19,882,551 | 2,202,517 |
Statements of Operations and Co
Statements of Operations and Comprehensive Loss - USD ($) | 12 Months Ended | ||
Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | |
Income Statement [Abstract] | |||
License revenue | $ 41,000 | $ 49,000 | $ 51,000 |
Operating expenses: | |||
Research and development | 29,113,000 | 27,218,000 | 19,172,000 |
General and administrative | 8,557,000 | 4,522,000 | 3,833,000 |
Total operating expenses | 37,670,000 | 31,740,000 | 23,005,000 |
Loss from operations | (37,629,000) | (31,691,000) | (22,954,000) |
Other income (expense), net: | |||
Interest income | 595,000 | 215,000 | 126,000 |
Interest expense | (1,932,000) | (2,052,000) | (339,000) |
Change in fair value of preferred stock warrants | 37,000 | 50,000 | 111,000 |
Total other income (expense), net | (1,300,000) | (1,787,000) | (102,000) |
Net loss | (38,929,000) | (33,478,000) | (23,056,000) |
Other comprehensive income (loss): | |||
Net unrealized gain (loss) on investments | (34,000) | 58,000 | (52,000) |
Comprehensive loss | $ (38,963,000) | $ (33,420,000) | $ (23,108,000) |
Net loss per common share, basic and diluted | $ (2.66) | $ (15.22) | $ (10.57) |
Weighted-average number of common shares outstanding, basic and diluted | 14,607,609 | 2,199,964 | 2,182,032 |
Statements of Changes in Conver
Statements of Changes in Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($) $ in Thousands | Total | Convertible Preferred Stock | Common Stock | Additional Paid-In Capital | Accumulated Deficit | Accumulated Other Comprehensive Income (Loss) |
Beginning balance at Dec. 31, 2014 | $ (70,441) | $ 2 | $ 1,019 | $ (71,456) | $ (6) | |
Beginning balance, shares at Dec. 31, 2014 | 39,787,568 | |||||
Beginning balance at Dec. 31, 2014 | $ 97,973 | |||||
Beginning balance, shares at Dec. 31, 2014 | 2,175,687 | |||||
Issuance of Series H convertible preferred stock, net of issuance costs | $ 33,440 | |||||
Issuance of Series H convertible preferred stock, net of issuance costs, shares | 6,376,037 | |||||
Exercise of stock options | 157 | 157 | ||||
Exercise of stock options, shares | 22,165 | |||||
Stock-based compensation | 1,062 | 1,062 | ||||
Other comprehensive income (loss) | (52) | (52) | ||||
Net Loss | (23,056) | (23,056) | ||||
Ending balance at Dec. 31, 2015 | (92,330) | $ 2 | 2,238 | (94,512) | (58) | |
Ending balance, shares at Dec. 31, 2015 | 46,163,605 | |||||
Ending Balance at Dec. 31, 2015 | $ 131,413 | |||||
Ending balance, shares at Dec. 31, 2015 | 2,197,852 | |||||
Cumulative effect of accounting change | 10 | (10) | ||||
Balance at January 1, 2016 | (92,330) | $ 2 | 2,248 | (94,522) | (58) | |
Balance, shares at January 1, 2016 | 46,163,605 | |||||
Balance at January 1, 2016 | $ 131,413 | |||||
Balance, shares at January 1, 2016 | 2,197,852 | |||||
Exercise of stock options | 10 | 10 | ||||
Exercise of stock options, shares | 4,665 | |||||
Stock-based compensation | 1,323 | 1,323 | ||||
Other comprehensive income (loss) | 58 | 58 | ||||
Net Loss | (33,478) | (33,478) | ||||
Ending balance at Dec. 31, 2016 | $ (124,417) | $ 2 | 3,581 | (128,000) | ||
Ending balance, shares at Dec. 31, 2016 | 46,163,605 | 46,163,605 | ||||
Ending Balance at Dec. 31, 2016 | $ 131,413 | $ 131,413 | ||||
Ending balance, shares at Dec. 31, 2016 | 2,202,517 | |||||
Exercise of stock options | 81 | 81 | ||||
Exercise of stock options, shares | 55,669 | |||||
Issuance of common stock pursuant to employee stock purchase plan | $ 426 | 426 | ||||
Issuance of common stock pursuant to employee stock purchase plan, shares | 50,121 | 50,121 | ||||
Stock-based compensation | $ 4,451 | 4,451 | ||||
Fractional shares adjustment upon reverse stock split, shares | 2 | |||||
Preferred stock converted into shares of common stock | 131,410 | $ 7 | 131,403 | |||
Preferred stock converted into shares of common stock, shares | (46,163,605) | |||||
Preferred stock converted into shares of common stock | $ (131,413) | |||||
Preferred stock converted into shares of common stock, shares | 6,690,066 | |||||
Initial public offering of common shares, net of issuance costs | 86,948 | $ 10 | 86,938 | |||
Initial public offering of common shares, net of issuance costs, shares | 9,775,000 | |||||
Convertible promissory notes converted into shares of common stock, net of costs to issue | 11,057 | $ 1 | 11,056 | |||
Convertible promissory notes converted into shares of common stock, net of costs to issue, shares | 1,109,176 | |||||
Preferred stock warrant liabilities converted into warrants to purchase shares of common stock | 89 | 89 | ||||
Other comprehensive income (loss) | (34) | (34) | ||||
Net Loss | (38,929) | (38,929) | ||||
Ending balance at Dec. 31, 2017 | $ 71,082 | $ 20 | $ 238,025 | $ (166,929) | $ (34) | |
Ending balance, shares at Dec. 31, 2017 | 19,882,551 |
Statements of Cash Flows
Statements of Cash Flows - USD ($) $ in Thousands | 12 Months Ended | ||
Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | |
OPERATING ACTIVITIES | |||
Net Loss | $ (38,929) | $ (33,478) | $ (23,056) |
Adjustments to reconcile net loss to net cash used in operating activities: | |||
Stock-based compensation | 4,451 | 1,323 | 1,062 |
Depreciation | 292 | 255 | 232 |
Noncash interest expense | 590 | 570 | 94 |
Change in fair value of preferred stock warrants | (37) | (50) | (111) |
Amortization of premium (discount) on investments, net | (19) | (9) | 5 |
Gain on disposal of property and equipment | (20) | (15) | |
Changes in operating assets and liabilities: | |||
Prepaid expenses and other current assets | (679) | (157) | (1,072) |
Accounts payable | 304 | 586 | 571 |
Accrued liabilities | 2,946 | 1,547 | 1,301 |
Deferred license revenue | (41) | (49) | (51) |
Deferred grant funding | (11) | (57) | (2) |
Net cash used in operating activities | (31,133) | (29,539) | (21,042) |
INVESTING ACTIVITIES | |||
Proceeds from the sale/maturity of marketable securities | 43,725 | 48,095 | 35,158 |
Purchases of marketable securities | (70,797) | (23,003) | (59,870) |
Purchases of property and equipment | (655) | (525) | (231) |
Proceeds from sale of property and equipment | 20 | 15 | |
Net cash (used in) provided by investing activities | (27,707) | 24,567 | (24,928) |
FINANCING ACTIVITIES | |||
Proceeds from offering of common stock, net of issuance costs | 88,618 | ||
Proceeds from issuance of convertible promissory notes, net of issuance costs | 7,338 | 3,374 | |
Proceeds from convertible promissory note subscriptions | 140 | ||
Proceeds from issuance of notes payable, net of issuance costs | 17,666 | ||
Proceeds from issuance of convertible preferred stock, net of issuance costs | 33,075 | ||
Principal payments on notes payable | (7,200) | (600) | |
Proceeds from issuance of common stock | 507 | 10 | 157 |
Cash paid for deferred equity issuance costs | (592) | (982) | |
Net cash provided by financing activities | 89,263 | 2,332 | 49,916 |
Net increase (decrease) in cash and cash equivalents | 30,423 | (2,640) | 3,946 |
Cash and cash equivalents, beginning of period | 5,510 | 8,150 | 4,204 |
Cash and cash equivalents, end of period | 35,933 | 5,510 | 8,150 |
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION | |||
Cash paid for interest | 1,210 | 1,460 | 124 |
Noncash investing and financing activities: | |||
Convertible preferred stock converted into shares of common stock | 131,410 | ||
Convertible promissory notes principal and accrued interest converted into shares of common stock | 11,057 | ||
Preferred stock warrant liabilities converted into warrants to purchase shares of common stock | 89 | ||
Fair value of preferred stock warrants issued in connection with notes payable | 287 | ||
Deferred equity issuance costs paid in previous periods reclassified to equity on effective date of initial public offering | 1,574 | ||
Deferred equity issuance costs in accounts payable and accrued liabilities | 96 | 226 | $ 543 |
Property and equipment purchases included in accounts payable and accrued liabilities | $ 111 | $ 28 |
Organization and Basis of Prese
Organization and Basis of Presentation | 12 Months Ended |
Dec. 31, 2017 | |
Organization Consolidation And Presentation Of Financial Statements [Abstract] | |
Organization and Basis of Presentation | 1. Organization and Basis of Presentation Tocagen Inc. (Tocagen or the Company) is a clinical-stage, cancer-selective gene therapy company focused on developing first-in-class, broadly-applicable product candidates designed to activate a patient’s immune system against their own cancer from within. The Company’s cancer-selective gene therapy platform is built on retroviral replicating vectors which are designed to selectively deliver therapeutic genes into the DNA of cancer cells. Tocagen’s gene therapy approach is designed to fight cancer through immunotherapeutic mechanisms of action without the autoimmune toxicities commonly experienced with other immunotherapies. From inception through December 31, 2017, the Company has devoted substantially all of its efforts to developing its gene therapy platform and its lead product candidate, Toca 511 & Toca FC, as well as raising capital and building its infrastructure. The Company has not generated revenues from its principal operations. Initial Public Offering On April 19, 2017, the Company completed its initial public offering (IPO), whereby the Company sold an aggregate of 9,775,000 shares of its common stock, at $10.00 per share, resulting in net proceeds of $86.9 million after underwriting discounts, commissions and offering costs of $10.8 million, of which $9.1 million of the costs were paid during the twelve months ended December 31, 2017. In addition, in connection with the IPO, all of the Company’s outstanding shares of convertible preferred stock were converted into an aggregate of 6,690,066 shares of the Company’s common stock, warrants to purchase up to 68,572 shares of the Company’s Series H convertible preferred stock were converted into warrants to purchase up to 9,936 shares of the Company’s common stock, each at an exercise price of $36.23 per share, and $11.1 million of aggregate principal and accrued interest underlying convertible promissory notes were automatically converted into an aggregate of 1,109,176 shares of the Company’s common stock at the IPO price of $10.00 per share. Liquidity The Company has a limited operating history and the sales and income potential of the Company’s business and patient markets are unproven. The Company has experienced net losses and negative cash flows from operating activities since its inception. As of December 31, 2017, the Company had an accumulated deficit of $166.9 million and working capital of $73.3 million available to fund future operations. As the Company continues to incur net losses, its transition to profitability is dependent upon the successful development, approval, and commercialization of its product candidates and achieving a level of revenues adequate to support the Company’s cost structure. The Company may never achieve profitability, and unless and until it does, the Company will continue to need to raise additional capital. In performing the first step of the assessment under Accounting Standards Codification Topic 205-40, Presentation of Financial Statements - Going Concern, the Company concluded that, based on its cash resources available as of December 31, 2017, which include the $86.9 million in net proceeds obtained from its IPO, it will have sufficient resources to fund its business for at least the next 12 months from the date of this filing. Use of Estimates The Company’s financial statements are prepared in accordance with accounting principles generally accepted in the United States (GAAP), which requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements, and expenses and related disclosures during the reporting period. Significant estimates in the Company’s financial statements relate to clinical trial accruals, the valuation of equity awards, and the development period used for license revenue recognition. Estimates are periodically reviewed in light of changes in circumstances, facts and experience. Actual results may differ from these estimates under different assumptions or conditions. Segment Reporting 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, or decision making group, in making decisions on how to allocate resources and assess performance. The Company views its operations and manages its business in one operating segment. No product revenue has been generated since inception and all assets are held in the United States. |
Summary of Significant Accounti
Summary of Significant Accounting Policies | 12 Months Ended |
Dec. 31, 2017 | |
Accounting Policies [Abstract] | |
Summary of Significant Accounting Policies | 2. Summary of Significant Accounting Policies Cash, Cash Equivalents and Marketable Securities Cash consists of the balance in a readily available checking account. Cash equivalents consist of money market funds, repurchase agreements, corporate debt securities and certificates of deposit with remaining maturities of three months or less at the time of purchase, and are considered highly liquid investments. Marketable securities consist of corporate debt securities, certificates of deposit, commercial paper, asset-backed securities and U.S. Treasury securities that have original maturities greater than three months at the time of purchase. The Company classifies its investments as available-for-sale and records such assets at fair value in the balance sheet, with unrealized gains and losses, if any, reported in stockholders’ equity (deficit). Realized gains and losses are calculated on the specific identification method and recorded to interest income. A decline in the market value of any marketable security below cost that is determined to be other-than-temporary results in a revaluation of its carrying amount to fair value and a new cost basis for the security. Impairment losses are recognized in other expense in the statement of operations. Concentration of Credit Risk and Off-Balance Sheet Risk Financial instruments that potentially subject the Company to significant concentration of credit risk consist primarily of cash equivalents and marketable securities. The Company’s investment policy includes guidelines for the quality of the related institutions and financial instruments, and defines allowable investments that the Company may invest in, which the Company believes minimizes the exposure to concentration of credit risk. Prepaid Expenses and Other Current Assets Prepaid expenses and other current assets primarily represent amounts related to insurance, clinical trial and manufacturing agreements, and investment interest receivable. Property and Equipment Property and equipment consists of furniture, fixtures, computers and software, laboratory and office equipment, and leasehold improvements. Property and equipment is stated at cost and depreciated over the estimated useful lives of the assets (three to five years) using the straight-line method. Leasehold improvements are depreciated using the straight-line method over the lesser of the remaining lease term or an estimated useful life of five years. Costs of major additions and betterments are capitalized and depreciated on a straight-line basis over their useful lives. Repairs and maintenance costs are expensed as incurred. Upon retirement or sale, the cost of assets disposed of and the related accumulated depreciation are removed from the accounts, and any resulting gain or loss is credited or charged to expense. Deferred Equity Issuance Costs Specific incremental costs directly attributable to a proposed or actual offering of securities are deferred and charged against the gross proceeds of the offering through additional paid-in capital. Impairment of Long-Lived Assets Long-lived assets consist of property and equipment. An impairment loss is recorded if and when events and circumstances indicate that assets might be impaired and the undiscounted cash flows estimated to be generated by those assets are less than the carrying amount of those assets. Fair Value of Financial Instruments The Company’s financial instruments consist principally of cash, cash equivalents, marketable securities, accounts payable, notes payable, convertible promissory notes payable and preferred stock warrant liabilities. The authoritative 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 authoritative accounting guidance establishes a three-tier fair value hierarchy that 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 such as quoted prices for similar assets or liabilities, quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities; and Level 3: Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. Clinical Trial Accruals Expenses related to clinical studies are based on estimates of the services received and efforts expended pursuant to the Company’s contract arrangements. The financial terms of these agreements are subject to negotiation, vary from contract to contract and may result in uneven payment flows. There may be instances in which payments made to the Company’s service providers will temporarily exceed the level of services provided and result in a prepayment of the clinical expense. Payments under some of these contracts depend on factors such as the successful enrollment of patients, site initiation and the completion of clinical milestones. The Company makes estimates of its accrued expenses as of each balance sheet date in its financial statements based on facts and circumstances known at that time. In accruing service fees, the Company estimates the time period over which services will be performed and the level of effort to be expended in each period. If the actual timing of the performance of services or the level of effort varies from its estimate, the Company adjusts the accrual or prepaid expense balance accordingly. Revenue Recognition Revenue is comprised of license revenue from the up-front payment that the Company received under its license and collaboration arrangement with Siemens Healthcare Diagnostics Inc. (Siemens). Revenue is recognized for each unit of accounting when all of the following criteria are met: • Persuasive evidence of an arrangement exists • Delivery of the Company’s obligations under the arrangement has occurred • The seller’s price to the buyer is fixed or determinable • Collectability is reasonably assured Amounts received prior to satisfying the revenue recognition criteria are recorded as deferred revenue in the Company’s balance sheets. Amounts expected to be recognized as revenue within the 12 months following the balance sheet date are classified as deferred revenue. Amounts not expected to be recognized as revenue within the 12 months following the balance sheet date are classified as long-term deferred revenue. The Company analyzes multiple-element arrangements based on the relevant authoritative guidance. Pursuant to the guidance, the Company evaluates multiple-element arrangements to determine (1) the deliverables included in the arrangement and (2) whether the individual deliverables represent separate units of accounting, or whether they must be accounted for as a combined unit of accounting. This evaluation involves subjective determinations and requires the Company to make judgments about the individual deliverables and whether such deliverables are separable from the other aspects of the contractual relationship. Deliverables are considered separate units of accounting provided that: (i) the delivered item(s) has value to the customer (a collaboration partner to date) on a standalone basis and (ii) if the arrangement includes a general right of return relative to the delivered item(s), delivery or performance of the undelivered item(s) is considered probable and substantially in its control. In assessing whether an item has standalone value, the Company considers factors such as the research, manufacturing and commercialization capabilities of the collaboration partner and the availability of the associated expertise in the general marketplace. In addition, the Company considers whether the collaboration partner can use the other deliverable(s) for their intended purpose without the receipt of the remaining element(s), whether the value of the deliverable is dependent on the undelivered item(s) and whether there are other vendors that can provide the undelivered element(s). Arrangement consideration that is fixed or determinable is allocated among the separate units of accounting using the relative selling price method. The Company determines the estimated selling price for units of accounting within each arrangement using vendor-specific objective evidence (VSOE) of selling price, if available, third-party evidence (TPE) of selling price if VSOE is not available, or best estimate of selling price (BESP) if neither VSOE nor TPE is available. The Company uses BESP to estimate the selling price, since it generally does not have VSOE or TPE of selling price for its units of accounting. Determining the BESP for a unit of accounting requires significant judgment. In developing the BESP for a unit of accounting, the Company considers applicable market conditions and relevant entity-specific factors, including factors that were contemplated in negotiating the agreement with the collaboration partner and estimated costs. The Company validates the BESP for units of accounting by evaluating whether changes in the key assumptions used to determine the BESP will have a significant effect on the allocation of arrangement consideration between multiple units of accounting. The Company then applies the applicable revenue recognition criteria to each of the separate units of accounting in determining the appropriate period and pattern of recognition. If there is no discernible pattern of performance and/or objectively measurable performance measures do not exist, then the Company recognizes revenue under the arrangement on a straight-line basis over the period it expects to complete its performance obligations. Research and Development Costs Research and development expenses consist primarily of salaries and other personnel related expenses including stock-based compensation costs, preclinical costs, clinical trial costs, costs related to acquiring and manufacturing clinical trial materials, contract services, facilities costs, overhead costs, and depreciation. All research and development costs are expensed as incurred. Patent Costs Costs related to filing and pursuing patent applications are recorded as general and administrative expense and expensed as incurred because recoverability of such expenditures is uncertain. Grant Funding The Company receives certain research and development funding through grants from nonprofit organizations that serve the brain cancer community. The Company evaluates the terms of each grant to assess the Company’s obligations, and such funding is recognized in the statement of operations as a reduction to research and development expense as the related costs are incurred to meet those obligations over the grant period. Certain grants contain repayment provisions contingent on future events, such as future revenue milestones related to the Company’s lead product candidate under development. For each repayment provision, the Company assesses if it is obligated to repay the funds provided by the other parties regardless of the outcome of the funded research and development. For each arrangement, the Company also reviews the repayment provisions to determine the likelihood of repayment at the execution of each grant and on an ongoing basis. If the likelihood of repayment of a grant is determined to be remote and the Company is not obligated to repay the funds regardless of the outcome of the funded research and development, the grant is recognized as a reduction to research and development expense as related costs are incurred over the grant period. The Company subsequently reviews the repayment provisions of each grant at each reporting date and will record a related grant repayment liability if and when such repayment obligation is determined to be probable. If, at the execution of a grant with repayment provisions, the probability of repayment is probable, the Company will record the grant as a liability until such time as the grant requirements have been satisfied and the repayment provisions have lapsed. Debt Issuance Costs Debt issuance costs incurred to obtain debt financing are deferred and are amortized over the term of the debt using the effective interest method. The costs are recorded as a reduction to the carrying value of the debt and the amortization expense is included in interest expense in the statement of operations. Warrants for Shares of Preferred Stock The Company accounts for warrants for shares of preferred stock with conversion features as liabilities in the accompanying balance sheets at their fair value on the date of issuance. The warrant liabilities are revalued at each balance sheet date until such instruments are exercised or expire, with changes in the fair value between reporting periods recorded as other income or expense in the statement of operations. All preferred stock warrant liabilities were reclassified to equity in connection with the IPO. Income Taxes The Company accounts for income taxes under the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences that have been included in the financial statements. Under this method, deferred tax assets and liabilities are determined on the basis of the differences between the financial statements and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. The Company provides a valuation allowance against net deferred tax assets unless, based upon the available evidence, it is more likely than not that the deferred tax assets will be realized. The Company records uncertain tax positions on the basis of a two-step process whereby (i) management determines whether it is more likely than not that the tax positions will be sustained on the basis of the technical merits of the position and (ii) for those tax positions that meet the more likely-than-not recognition threshold, management recognizes the largest amount of tax benefit that is more than 50 percent likely to be realized upon ultimate settlement with the related tax authority. The Company will recognize interest and penalties in income tax expense if and when incurred. Comprehensive Income (Loss) All components of comprehensive income (loss) are reported in the financial statements in the period in which they are recognized. Other comprehensive income (loss) is defined as the change in equity during a period from transactions and other events and circumstances from non-owner sources, including unrealized gains and losses on investments. The Company’s only component of other comprehensive loss is unrealized gains (losses) on investments. Comprehensive gains (losses) have been reflected in the statements of operations and comprehensive loss for all periods presented. Stock-Based Compensation Stock-based compensation expense represents the cost of the grant date fair value of stock awards, including stock options, and stock purchase rights granted to employees. For awards with time-based vesting provisions, the Company estimates the fair value of stock options on the date of grant using the Black-Scholes option pricing model and recognizes the expense over the requisite service period of the awards, which is generally the vesting period, on a straight-line basis. For awards with performance-based vesting provisions, the Company estimates the fair value of stock option grants on the date of grant, or the date when all of the terms of the grant have been agreed to, if later, and recognizes the expense based on the probability of the occurrence of the individual milestones at each reporting period. The expense is recognized over the implicit service period that commences once management believes the performance criteria are probable of being met. For purchase rights, the Company estimates the fair value of the purchase as of the plan enrollment date and recognizes expense on a straight-line basis over the applicable offering period. The Company accounts for forfeitures when they occur, and reverses any compensation cost previously recognized for awards for which the requisite service has not been completed, in the period that the award is forfeited. The Company accounts for stock options and stock warrants granted to non-employees using the fair value approach. These option and warrant grants are subject to periodic revaluation over their vesting terms. Net Loss Per Share Basic and diluted net loss per common share for the periods presented is computed by dividing net loss by the weighted-average number of common shares outstanding during the respective periods, without consideration of common stock equivalents as they are anti-dilutive. Common stock equivalents that could potentially dilute earnings in the future are comprised of shares issuable upon the conversion of all outstanding principal and accrued interest related to convertible promissory notes payable, shares issuable upon the conversion of convertible preferred stock, options to purchase shares of common stock outstanding under the Company’s equity incentive plan and warrants for the purchase of shares of common and preferred stock. For all periods presented, there is no difference in the number of shares used to calculate basic and diluted shares outstanding due to the Company’s net loss position. Common stock equivalents from potentially dilutive securities, excluding shares issuable upon the conversion of all outstanding principal and accrued interest related to convertible promissory notes, that are not included in the calculation of diluted net loss per share, because to do so would be anti-dilutive, are as follows: Years Ended December 31, 2017 2016 2015 Common stock options 2,589,348 1,385,855 738,809 Common stock warrants 10,660 724 724 Convertible preferred stock (as-converted) — 6,690,066 6,690,066 Convertible preferred stock warrants (as-converted) — 9,936 9,936 Total 2,600,008 8,086,581 7,439,535 Recent Accounting Pronouncements In May 2014, the Financial Accounting Standards Board (FASB) issued new revenue recognition guidance which outlines a single comprehensive revenue model for entities to use in accounting for revenue arising from contracts with customers. The guidance supersedes most current revenue recognition guidance, including industry-specific guidance. The guidance provides that an entity recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The guidance will be effective on January 1, 2018. The guidance allows for either a full retrospective adoption, in which the standard is applied to all of the periods presented, or a modified retrospective adoption, in which the standard is applied to the most current period presented in the financial statements. As of December 31, 2017, revenue has been generated exclusively from the Company’s license and collaboration arrangement with Siemens. The Company has completed its evaluation of the impact that this guidance has on its financial position and results of operations as it relates to this single arrangement, and has elected the modified retrospective adoption method. Overall, the Company does not expect the timing of revenue recognition under the new standards to be materially different from the Company’s current revenue recognition policy. Based on the Company’s analysis of the open contract as of December 31, 2017, the cumulative effect of applying the new standards is not material. The Company is finalizing the new required disclosures. In January 2016, the FASB issued guidance that amends certain aspects of the recognition, measurement, presentation and disclosure of financial instruments. The amendments include the elimination of the available-for-sale classification of equity investments and requires equity investments with readily determinable fair values to be measured at fair value with changes in fair value recognized in net income (loss). The guidance is effective for fiscal years and interim periods within those years beginning after December 15, 2017, and requires a cumulative-effect adjustment to the balance sheet as of the beginning of the fiscal year of adoption. Early adoption is not permitted. The Company’s marketable securities are currently accounted for as available-for-sale financial instruments with changes in fair value recognized in other comprehensive income (loss). At the time of adoption, any amounts in accumulated other comprehensive income (loss) related to such financial instruments would be reclassified to non-operating income (expense) in the statement of operations. As of December 31, 2017, a net unrealized loss of $34,000 related to these investments was recorded in accumulated other comprehensive loss in the accompanying balance sheet. In February 2016, the FASB issued accounting guidance that amends the existing accounting standards for leases. Under the guidance, lessees will be required to recognize for all leases, with the exception of short-term leases, a lease liability, which is a lessee’s obligation to make lease payments arising from a lease, measured on a discounted basis and a right-of-use asset, which is an asset that represents the lessee’s right to use, or control the use of, a specified asset for the lease term. The standard is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Early adoption is permitted. The Company is still in the process of evaluating the effect of adoption on its financial statements and expects to adopt the standard on January 1, 2019. The adoption will lead to an increase in the assets and liabilities recorded on the balance sheets primarily due to the lease agreement attributable to leased lab and office space. |
Fair Value of Financial Instrum
Fair Value of Financial Instruments | 12 Months Ended |
Dec. 31, 2017 | |
Fair Value Disclosures [Abstract] | |
Fair Value of Financial Instruments | 3. Fair Value of Financial Instruments Fair Values of Assets and Liabilities Measured on a Recurring Basis The following tables summarize the Company’s assets and liabilities that require fair value measurements on a recurring basis and their respective input levels based on the fair value hierarchy (in thousands): Fair Value Measurements at End of Period Using: Total Quoted Market Prices for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) December 31, 2017 Cash equivalents: Corporate debt securities $ 8,274 $ — $ 8,274 $ — Repurchase agreements 5,000 — 5,000 — $ 13,274 $ — $ 13,274 $ — Marketable securities: Corporate debt securities $ 24,713 $ — $ 24,713 $ — Certificates of deposit 13,651 — 13,651 — Commercial paper 12,329 — 12,329 — Asset-backed securities 2,099 — 2,099 — $ 52,792 $ — $ 52,792 $ — Fair Total Quoted Market Prices for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) December 31, 2016 Cash equivalents: Certificates of deposit $ 240 $ — $ 240 $ — Marketable securities: Certificates of deposit $ 22,777 $ — $ 22,777 $ — U.S. Treasury securities 2,958 2,958 — — $ 25,735 $ 2,958 $ 22,777 $ — Preferred stock warrant liabilities $ 126 $ — $ — $ 126 Marketable Securities. For fair values determined by Level 1 inputs, which utilize quoted prices in active markets for identical assets, the level of judgment required to estimate fair value is relatively low. The fair values of investments in U.S. treasury securities were determined using Level 1 inputs. Fair values determined by Level 2 inputs, which utilize data points that are observable such as quoted prices, interest rates and yield curves, require the exercise of judgment and use of estimates, that if changed, could significantly affect the Company’s financial position and results of operations. Investments in corporate debt securities, certificates of deposit, commercial paper, repurchase agreements and asset-backed securities are valued using Level 2 inputs. Level 2 securities are initially valued at the transaction price and subsequently valued and reported utilizing inputs other than quoted prices that are observable either directly or indirectly, such as quotes from third-party pricing vendors. There were no transfers in or out of Level 1 or Level 2 investments during the years ended December 31, 2017 or 2016. At December 31, 2017 and 2016, the Company had investments in money market funds of $20.2 million and $2.2 million, respectively, that were measured at fair value using the net asset value per share (or its equivalent) that have not been classified in the fair value hierarchy. The funds invest primarily in U.S. government securities. Warrant Liabilities. The Company’s preferred stock warrants are accounted for as liabilities and measured at fair value on a recurring basis as they are convertible into preferred stock which is contingently redeemable under conditions that are not in the control of the Company. The Company estimates fair values of these warrant liabilities utilizing the Black-Scholes option pricing model, which requires Level 3 inputs. Estimating fair values of derivative financial instruments, including Level 3 instruments, requires the use of significant and subjective inputs that may, and are likely to, change over the duration of the instrument with related changes in internal and external market factors, including changes in the estimated fair value of the Company’s equity securities. The following table summarizes the activity in liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3 inputs) (in thousands): Preferred Stock Warrant Liabilities Balance at December 31, 2015 $ 176 Gain on warrant valuation included in other income (expense), net (50 ) Balance at December 31, 2016 126 Gain on warrant valuation included in other income (expense), net (37 ) Conversion of preferred stock warrant liabilities into warrants to purchase shares of common stock (89 ) Balance at December 31, 2017 $ — Fair Values of Other Financial Instruments The carrying amounts of certain of the Company’s financial instruments, including cash and accounts payable, approximate their respective fair values due to their short-term nature. The carrying amount of the Company’s notes payable of $10.8 million at December 31, 2017 approximated their fair value as the terms of the notes are consistent with the market terms of transactions with similar profiles of one of the lenders as of those dates (Level 3 inputs). |
Certain Financial Statement Cap
Certain Financial Statement Caption Information | 12 Months Ended |
Dec. 31, 2017 | |
Balance Sheet Related Disclosures [Abstract] | |
Certain Financial Statement Caption Information | 4. Certain Financial Statement Caption Information Marketable Securities The following is a summary of the Company’s marketable securities (in thousands): Maturity (in years) Amortized Cost Unrealized Gain Unrealized Loss Fair Value December 31, 2017: Corporate debt securities 1 or less $ 21,097 $ — $ (16 ) $ 21,081 Corporate debt securities >1 and <5 3,636 — (4 ) 3,632 Certificates of deposit 1 or less 13,658 — (7 ) 13,651 Commercial paper 1 or less 12,333 — (4 ) 12,329 Asset-backed securities 1 or less 2,099 — — 2,099 $ 52,823 $ — $ (31 ) $ 52,792 December 31, 2016: Certificates of deposit 1 or less $ 19,299 $ 1 $ (2 ) $ 19,298 Certificates of deposit >1 and <5 3,478 1 — 3,479 U.S. Treasury securities 1 or less 1,678 — — 1,678 U.S. Treasury securities >1 and <5 1,280 4 (4 ) 1,280 $ 25,735 $ 6 $ (6 ) $ 25,735 The Company has classified all of its available-for-sale investment securities, including those with maturity greater than one year, as current assets on the balance sheet based on the highly liquid nature of these investment securities and because these investment securities are considered available for use in current operations. There were no impairments considered other-than-temporary during the periods presented, as it is management’s intention and ability to hold the securities until a recovery of the cost basis or recovery of fair value. Gross realized gains and losses on sales of marketable securities were immaterial for all periods presented. Property and Equipment Property and equipment is comprised of (in thousands): December 31, 2017 2016 Laboratory equipment $ 3,553 $ 2,841 Computers, software and office equipment 232 187 Furniture and fixtures 21 21 Leasehold improvements 117 108 3,923 3,157 Less: accumulated depreciation (2,706 ) (2,414 ) $ 1,217 $ 743 Depreciation expense was $0.3 million for each of the years ended December 31, 2017 and 2016. Accrued Liabilities Accrued liabilities are comprised of (in thousands): December 31, 2017 2016 Clinical trial expenses $ 2,809 $ 2,196 Payroll and other employee-related expenses 2,489 728 Contract manufacturing services 1,536 1,508 Professional fees 276 459 Contract research services 104 114 Interest payable 77 120 Other 829 312 Total accrued liabilities $ 8,120 $ 5,437 |
Notes Payable
Notes Payable | 12 Months Ended |
Dec. 31, 2017 | |
Debt Disclosure [Abstract] | |
Notes Payable | 5. Notes Payable Loan Agreement On October 30, 2015, the Company entered into a Loan and Security Agreement (the Loan Agreement) with two lenders whereby it borrowed $18.0 million (the Loans). Balances under the Loan Agreement bear a floating rate of interest equal to the greater of 7.75% or the monthly prime rate plus 4.50% (8.75% and 8.00% at December 31, 2017 and 2016, respectively), and are due in monthly principal and interest payments, with final maturity of the Loans in May 2019. Each Loan bears a final payment fee of 7.95% of the original principal amount due upon maturity. The costs incurred to issue the Loans of $0.6 million were deferred and are included in the discount to the carrying value of the Loans in the accompanying balance sheets. The Loans also include a final payment fee of $1.4 million due at the earlier of prepayment or the maturity date of the Loans. The deferred costs and the final payment fee are amortized to interest expense over the expected term of the Loans using the effective interest method. The effective interest rates on the Loans at December 31, 2017 and 2016 are 11.94% and 11.19%, respectively. The aggregate carrying amounts of the Loans are comprised of the following (in thousands): December 31, 2017 2016 Principal $ 10,200 $ 17,400 Add: accreted liability for final payment fee 869 462 Less: unamortized discount (244 ) (421 ) $ 10,825 $ 17,441 The Loans are secured by substantially all of the Company’s assets other than its intellectual property, except rights to payment from the sale, licensing or disposition of such intellectual property. The Company is also required to maintain its primary operating accounts at all times with one of the lenders. The Loan Agreement contains customary conditions of borrowing, events of default and covenants, including covenants that restrict the Company’s ability to dispose of assets, merge with or acquire other entities, incur indebtedness and make distributions to holders of its capital stock. Should an event of default occur, including the occurrence of a material adverse change, the Company could be liable for immediate repayment of all obligations under the Loan Agreement. At December 31, 2017, the Company was in compliance with the covenants contained in the Loan Agreement. Future maturities of the Loans, including the final payment fee, as of December 31, 2017 are as follows (in thousands): December 31, 2017 Year ending December 31, 2018 $ 7,200 Year ending December 31, 2019 4,431 11,631 Unaccreted balance for final payment fee on Loans (562 ) Unamortized discounts (244 ) 10,825 Less current portion (7,200 ) Noncurrent portion $ 3,625 Convertible Promissory Notes Payable and Subscription Liability During the three months ended March 31, 2017 and December 31, 2016, the Company issued convertible promissory notes to investors in aggregate principal amount of $7.5 million and $3.4 million, respectively, for a total aggregate principal amount of $10.9 million (the Convertible Notes). Of the Convertible Notes issued during the three months ended March 31, 2017, $140,000 was subscribed for at December 31, 2016, $250,000 was issued to a member of the Company’s board of directors and $10,000 was issued to the Company’s chief executive officer. The Convertible Notes, which bore interest at 7% per annum, were unsecured and were subordinated to the Loans. At December 31, 2016, the aggregate carrying amount of the Convertible Notes was $3.4 million, which is net of an unamortized discount of $34,000. At December 31, 2016, the Convertible Notes included $1.0 million issued to members of the Company’s board of directors and $25,000 issued to the Company’s chief executive officer. The effective interest rate on the Convertible Notes at December 31, 2016 was 7.54%. Upon completion of the Company’s IPO on April 19, 2017, $11.1 million of aggregate principal and accrued interest underlying the Convertible Notes were automatically converted into an aggregate of 1,109,176 shares of the Company’s common stock at the IPO price of $10.00 per share. |
Stockholders' Equity (Deficit)
Stockholders' Equity (Deficit) | 12 Months Ended |
Dec. 31, 2017 | |
Equity [Abstract] | |
Stockholders' Equity (Deficit) | 6. Stockholders’ Equity (Deficit) In March 2017, the Company’s board of directors and stockholders approved a 1-for-6.9 reverse stock split of the Company’s outstanding common stock. The accompanying financial statements and notes to the financial statements give retroactive effect to the reverse stock split for all periods presented. Upon completion of the Company’s IPO, all of the Company’s outstanding shares of convertible preferred stock were converted into an aggregate of 6,690,066 shares of the Company’s common stock. As of December 31, 2017, the Company’s authorized capital stock consists of 200,000,000 shares of common stock, par value $0.001 per share, and 10,000,000 shares of preferred stock, par value $0.001 per share. The Company had 19,882,551 and 2,202,517 shares of common stock outstanding as of December 31, 2017 and 2016, respectively. Common Stock Reserved for Future Issuance Common stock reserved for future issuance at December 31, 2017 and 2016 is as follows and for 2016 excludes shares issued upon conversion of all outstanding principal and accrued interest related to the convertible promissory notes payable upon completion of the Company’s IPO on April 19, 2017: December 31, 2017 2016 Issued and Outstanding: Stock options 2,589,348 1,385,855 Warrants for common stock 10,660 724 Shares reserved for issuance under the ESPP 199,879 — Shares reserved for future award grants 513,333 172,495 Conversion of all outstanding convertible preferred stock — 6,690,070 Conversion of preferred stock warrants issued and outstanding — 9,936 |
Equity Incentive Plans and Stoc
Equity Incentive Plans and Stock-Based Compensation | 12 Months Ended |
Dec. 31, 2017 | |
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract] | |
Equity Incentive Plans and Stock-Based Compensation | 7. Equity Incentive Plans and Stock-Based Compensation 2017 Equity Incentive Plan In March 2017, the Company’s board of directors and stockholders approved and adopted the Company’s 2017 Equity Incentive Plan (the 2017 Plan), which became effective on April 12, 2017. The 2017 Plan provides for the grant of incentive stock options (ISOs), nonstatutory stock options, stock appreciation rights, restricted stock awards, restricted stock unit awards, performance based stock awards, other forms of equity compensation and performance cash awards. ISOs may be granted only to employees. All other awards may be granted to employees, including officers, and to non-employee directors and consultants of the Company and its affiliates. Initially, 1,600,000 new shares of common stock were approved for issuance under the 2017 Plan and, on April 12, 2017, 75,517 shares of common stock reserved for issuance under the Company’s 2009 Equity Incentive Plan, as amended (the 2009 Plan), were added to the shares initially reserved under the 2017 Plan. No further grants will be made under the 2009 Plan and any shares subject to outstanding stock options under the 2009 Plan that would otherwise be returned to the 2009 Plan will instead be added to the shares reserved under the 2017 Plan. Additionally, the number of shares of common stock reserved for issuance under the 2017 Plan will automatically increase on January 1 of each calendar year through January 1, 2027, by 4% of the total number of shares of the Company’s capital stock outstanding on December 31 of the preceding calendar year, or a lesser number of shares determined by the Company’s board of directors. As of December 31, 2017, awards for up to 3,102,681 shares of common stock are reserved under the 2009 Plan and the 2017 Plan, of which 2,589,348 shares are reserved for issuance upon exercise of granted and outstanding stock options and 513,333 shares are available for future grants. On January 1, 2018, the number of shares available for future grants under the 2017 Plan was increased by 795,302 shares such that the total number of shares available for future grants as of January 1, 2018 was 1,308,635 shares. All grants of options to purchase common stock under the 2017 Plan expire in 10 years. Grants with time-based vesting provisions are subject to a four-year vesting schedule with 25% vesting after the first year, and the balance vesting monthly over the remaining 36 months. Grants with performance-based vesting provisions vest upon the achievement of three separate development and regulatory milestones, with one-third of the options vesting upon the achievement of each milestone. The following table summarizes stock option activity under the 2009 Plan and the 2017 Plan: Shares Subject to Options Weighted- Average Exercise Price per Share Weighted- Average Remaining Contractual Term (in years) Aggregate Intrinsic Value (in thousands) Outstanding at December 31, 2016 1,385,855 $ 11.35 Granted 1,400,245 $ 14.92 Exercised (55,669 ) $ 1.45 Forfeitures and cancellations (141,083 ) $ 14.39 Outstanding at December 31, 2017 2,589,348 $ 13.33 8.1 $ 2,643 Time-based options at December 31, 2017: Outstanding 2,400,697 $ 13.09 8.1 $ 2,643 Vested and expected to vest 2,400,697 $ 13.09 8.1 $ 2,643 Exercisable 742,213 $ 8.68 5.6 $ 2,602 Performance-based options at December 31, 2017: Outstanding 188,651 $ 16.30 8.9 — Vested and expected to vest — — — — Exercisable — — — — The following table summarizes certain information regarding stock options (in thousands): Years Ended December 31, 2017 2016 2015 Fair value of options vested during the period $ 2,194 $ 1,087 $ 862 Cash received from options exercised during the period $ 81 $ 10 $ 157 Intrinsic value of options exercised during the period $ 677 $ 62 $ 160 The aggregate intrinsic value of options is calculated as the difference between the exercise price of the options and the fair value of the Company’s common stock for those options that had exercise prices lower than the fair value of the Company’s common stock. 2017 Employee Stock Purchase Plan In March 2017, the Company’s board of directors and stockholders approved and adopted the Company’s 2017 Employee Stock Purchase Plan (ESPP) whereby eligible employees may elect to withhold up to 15% of their earnings to purchase shares of the Company’s common stock at a price per share equal to the lower of (i) 85% of the fair market value of a share of the Company’s common stock on the first date of an offering or (ii) 85% of the fair market value of a share of the Company’s common stock on the date of purchase (purchase right). The ESPP became effective on April 12, 2017. Initially, 250,000 shares of the Company’s common stock were approved for issuance under the ESPP pursuant to purchase rights granted to the Company’s employees or to employees of any of the Company’s designated affiliates. The number of shares of common stock reserved for issuance will automatically increase on January 1 of each calendar year through January 1, 2027, by the lesser of (a) 1% of the total number of shares of the Company’s common stock outstanding on December 31 of the preceding calendar year, (b) 300,000 shares, or (c) a number determined by the Company’s board of directors that is less than (a) and (b). As of December 31, 2017, the Company had issued 50,121 199,879 Stock-Based Compensation Expense The assumptions used in the Black-Scholes option pricing model to determine the fair value of the employee stock option grants with both time-based and performance-based vesting provisions and stock purchase rights were as follows: Years Ended December 31, 2017 2016 2015 Time-Based Vesting Provisions Performance-Based Vesting Provisions ESPP Purchase Rights Time-Based Vesting Provisions Risk-free interest rate 1.83% - 2.27% 1.98% - 2.17% 1.04% - 1.82% 1.63% 1.61% Expected volatility 75.9% - 87.5% 75.2% - 76.3% 65.7% - 84.4% 73.3% - 73.5% 73.5% - 86.8% Weighted-average volatility 82.2% 75.9% 69.6% 73.4% 82.2% Dividend yield 0% 0% 0% 0% 0% Weighted-average expected term (in years) 6.1 6.3 1.3 6.1 6.1 Weighted-average grant date fair value per share $ 10.39 $ 6.73 $ 4.61 $ 9.69 $ 13.56 Risk-free interest rate . The Company bases the risk-free interest rate assumption on U.S. Treasury constant maturities with maturities similar to those of the expected term of the award being valued. Expected volatility . Due to the Company’s limited trading of its common stock and lack of company-specific historical or implied volatility data, the Company has based its estimate of expected volatility on the historical volatility of a group of similar companies in the life sciences industry whose shares are publicly traded. The Company selects the peer group based on comparable characteristics, including development stage, product pipeline, and enterprise value. The Company computes historical volatility data using the daily closing prices for the selected companies’ shares during the equivalent period of the calculated expected term of the stock-based awards. The Company will continue to apply this process until sufficient amount of historical information regarding the volatility of its own stock price become available. Expected term. The expected term of employee stock options granted with time-based vesting provisions was calculated using the simplified method which utilizes the midpoint between the weighted average time of vesting and the end of the contractual term. The expected term of employee stock options granted with performance-based vesting provisions was calculated using the midpoint between the estimated service period and the contractual term of the option. These methods were utilized due to a lack of historical exercise behavior by the Company's employees. The expected term for stock purchase rights is the term from the date of grant to the date of purchase. Expected dividend yield . The Company bases the expected dividend yield assumption on the fact that it has never paid, and does not expect to pay, dividends in the foreseeable future. The Company calculates the estimated fair value of each non-employee stock option award at the date of grant using Black-Scholes option pricing model with the assumptions generally consistent with those used for employee stock options, with the exception of expected term, which is over the contractual life. The Company has not recognized non-cash stock-based compensation expense for outstanding options to purchase 188,651 shares of common stock with performance-based vesting provisions after its evaluation that the occurrence of the individual milestones is not probable as of December 31, 2017. Total non-cash stock-based compensation expense for all stock awards and purchase rights, net of forfeitures recognized as they occur, that was recognized in the statements of operations is as follows (in thousands): Years Ended December 31, 2017 2016 2015 Research and development $ 1,783 $ 562 $ 456 General and administrative 2,668 761 606 Total $ 4,451 $ 1,323 $ 1,062 Unrecognized compensation expense for stock options at December 31, 2017 was $16.3 million which is expected to be recognized over a weighted-average period of 3.0 years and unrecognized compensation expense for stock purchase rights at December 31, 2017 was $0.4 million which is expected to be recognized over a weighted-average period of 0.7 years. |
License and Collaboration Agree
License and Collaboration Agreements | 12 Months Ended |
Dec. 31, 2017 | |
Organization Consolidation And Presentation Of Financial Statements [Abstract] | |
License and Collaboration Agreements | 8. License and Collaboration Agreements Siemens License and Collaboration In November 2011, the Company entered into a laboratory services and license agreement with Siemens, which was amended in June 2015, pursuant to which the Company agreed to engage Siemens (i) to develop and perform certain in vitro diagnostic assays in connection with the cancer therapy trials of Toca 511 & Toca FC, (ii) concurrently and/or thereafter, to further develop, obtain U.S. Food and Drug Administration (FDA) approval for, and perform one or more of such in vitro diagnostic assays as companion diagnostics for Toca 511 & Toca FC after Toca 511 & Toca FC have received marketing approval from the FDA, and (iii) following FDA approval of such in vitro diagnostic assay as a companion diagnostic, to perform such in vitro diagnostic monitoring assays as necessary in connection with post-marketing clinical trials of Toca 511 & Toca FC. The Company granted Siemens the licensed intellectual property covered by the agreement on an exclusive and non-exclusive basis, depending on Siemens’ use of such intellectual property. Under the terms of the agreement, Siemens paid the Company an initial upfront payment of $0.5 million in December 2011. Under the terms of the June 2015 amendment, the Company is required to reimburse Siemens for 50% of future costs of the new assay development. Additionally, beginning with the first commercial sale of a product that has received approval for clinical use under the agreement, Siemens will pay the Company a royalty in the 10-20 percent range of net assay revenue with respect to approved designated assay products and net sales revenue with respect to approved in vitro diagnostic products, until the fifth anniversary of such commercial sale, subject to certain reductions. Beginning with the first commercial sale of Toca 511 or Toca FC, the Company will pay a royalty to Siemens in the low single-digit percentage range on net product sales of Toca 511 & Toca FC for sales up to the mid nine-digit dollar range per year, until the fifth anniversary of such commercial sale. In order to account for multiple-element arrangements, the Company identified the deliverables within the agreement and evaluated which deliverables represent units of accounting. The deliverables under the agreement included (i) a license under the Company’s licensed intellectual property, (ii) transfer of existing assays, (iii) training, and (iv) collaboration (i.e., the Company’s technical/regulatory support) with Siemens for its development of clinical assays to be used as companion diagnostics for the Company’s brain cancer product candidate. The collaboration arrangement does not contain a general right of return relative to the delivered item(s). Based on the terms of the agreement, the Company identified one single unit of accounting for the deliverables and the up-front payment was allocated to it. The up-front payment is being recognized as license revenue on a straight-line basis over the estimated development period, and royalty revenue and royalty expenses will thereafter be recorded as earned and incurred, respectively. USC Technology License In October 2007, the Company entered into a license agreement with the University of Southern California (USC) pursuant to which the Company received a worldwide, exclusive license to, among other things, manufacture and market products utilizing the inventions claimed and described in the patents as described in the agreement. Under the terms of the agreement, the Company paid an initial license fee to USC and issued to USC shares of the Company’s common stock. Pursuant to the agreement, the Company owes USC a royalty in the low single-digit percent range of the Company’s and the Company’s sub-licensees’ net sales of products covered by the agreement. In addition, the Company owes USC an additional royalty in the low single-digit percent range of revenue from its sub-licensees. Once the Company’s and its sub-licensees’ net sales reach an amount in the mid seven-digit dollar range, the minimum annual royalty payment due to USC will be in the low six-digit dollar range. The Company’s royalty obligations continue on a licensed product-by-licensed product and country-by-country basis until the expiration of the last valid claim in the licensed patent covering a licensed product in such country. In October 2010, the Company exercised its option under the agreement to reduce the royalty rate to a lower single-digit percent range. |
Grant Agreements
Grant Agreements | 12 Months Ended |
Dec. 31, 2017 | |
Grant Agreement [Abstract] | |
Grant Agreements | 9. Grant Agreements In August 2017, the Company was awarded a $2.0 million grant by the U.S. Food and Drug Administration Office of Orphan Products Development to support its Phase 3 clinical trial (OOPD Grant). Under the grant agreement, the Company will be reimbursed for qualifying expenses over a four-year period subject to the availability of funds and satisfactory progress of the trial. During the year ended December 31, 2017, the Company has received and recorded reimbursable amounts totaling $0.5 million relating to the OOPD Grant as an offset against research and development costs incurred during the period. The grants listed below contain repayment provisions contingent on future events which the Company reviewed at the execution of each grant and continues to review on an ongoing basis to determine the likelihood of repayment. Accelerate Brain Cancer Cure, Inc. (ABC2 Grant) Terms of the ABC2 Grant include a revenue share clause whereby an amount up to a maximum of $0.2 million is payable to ABC2 if and when net sales of the Company’s initial product candidate reach a total of $5.0 million within 10 years of the ABC2 Grant date of July 15, 2009. In addition, the ABC2 Grant includes a conversion option whereby the payment amount may be converted to common stock under certain circumstances. As the Company has not recognized any such revenues, no repayment liability has been recorded as of December 31, 2017. American Brain Tumor Association (ABTA Grant) Terms of the ABTA Grant include a revenue share clause whereby an amount up to a maximum of $0.2 million is payable to ABTA if and when net sales of the Company’s initial product candidate reach a total of $5.0 million within 10 years of the ABTA Grant date of April 21, 2010. As the Company has not recognized any such revenues, no repayment liability has been recorded as of December 31, 2017. Voices Against Brain Cancer (VABC Grant) Terms of the VABC Grant include a recovery clause whereby an amount up to a maximum of $0.3 million is payable to VABC if and when (1) net sales of the Company’s initial product candidate reach a total of $5.0 million within five years of the VABC Grant date of June 5, 2013, or (2) the Company enters into a definitive agreement for a favorable transaction resulting in (a) the sale of all or substantially all of the Company’s capital stock in a transaction other than an initial public offering, (b) a favorable merger transaction of the Company with another entity, or (c) the sale of all or substantially all of the Company’s assets for cash within a certain time period. In addition, the VABC Grant includes a conversion option whereby the payment may be converted to common stock under certain circumstances. As none of the recovery payment events were considered probable to occur as of December 31, 2017, no repayment liability has been recorded. |
Income Taxes
Income Taxes | 12 Months Ended |
Dec. 31, 2017 | |
Income Tax Disclosure [Abstract] | |
Income Taxes | 10. Income Taxes The Company has not recorded a current or deferred tax expense or benefit for the years ended December 31, 2017, 2016 or 2015. The (benefit) provision for income taxes differs from the amount of income tax determined by applying the applicable U.S. statutory federal income tax rate to pretax income as a result of the following differences: Years Ended December 31, 2017 2016 2015 Federal statutory rate 34.0 % 34.0 % 34.0 % Adjustments for tax effects of: State taxes, net 5.7 % 5.6 % 5.6 % Permanent adjustments (4.5 )% (5.4 )% (4.8 )% Tax Cuts and Jobs Act (3.7 )% — % — % Net operating loss carryovers not recognized (30.4 )% (32.8 )% (33.3 )% Valuation allowance (1.0 )% (1.1 )% (1.7 )% Other (0.1 )% (0.3 )% 0.2 % Effective income tax rate — % — % — % Deferred taxes are recognized for temporary differences between the basis of assets and liabilities for financial statement and income tax purposes. Significant components of the Company’s deferred taxes are as follows (in thousands): December 31, 2017 2016 Deferred tax assets: Depreciation and amortization $ 52 $ 52 Deferred license revenue 15 38 Share-based compensation 1,459 1,062 Accrued liabilities and other 808 796 Total deferred tax assets 2,334 1,948 Less valuation allowance (2,334 ) (1,948 ) Net deferred tax assets $ — $ — The Company has evaluated the positive and negative evidence bearing upon the realizability of its deferred tax assets. Based upon the Company’s history of operating losses, the Company has concluded that it is more likely than not that the benefit of its deferred tax assets will not be realized. Accordingly, the Company has provided a full valuation allowance for deferred tax assets as of December 31, 2017 and 2016. During 2017 and 2016, the valuation allowance increased by $0.4 million and $0.4 million, respectively. The Company has federal and California net operating loss carryforwards which may be available to offset future income tax liabilities. As of December 31, 2017, the Company has federal and California net operating loss carryforwards of $137.8 million and $41.5 million, respectively. The federal and state net operating losses begin to expire in 2028 unless previously utilized. Excluded from the California net operating loss carryforward are net operating losses for the years ended December 31, 2013, 2014, 2015, 2016 and 2017 which were impacted by a California Supreme Court ruling on December 31, 2015. This ruling clarified how companies are allowed to apportion income or losses in the state. As a result of the ruling, the Company has completed an analysis to determine the re-apportionment of its losses to California using the required single sales factor market sourcing method for 2013 through 2017 by treating its passive interest income as California-source income which results in a 100% apportionment percentage to California. While this portion may not reach the more-likely-than-not recognition threshold, the Company has excluded a cumulative net operating loss of $109.6 million from its California net operating loss carryforward. As of December 31, 2017, the Company has federal and California research and development tax credit carryforwards of $20.5 million and $4.7 million, respectively. The federal research and development tax credits begin to expire in 2028 unless previously utilized. The California credits do not expire. Pursuant to Internal Revenue Code (IRC) Sections 382 and 383, annual use of a company’s net operating loss and tax credit carryforwards may be limited if there is a cumulative change in ownership of greater than 50% within a three-year period. The amount of the annual limitation is determined based on the value of the Company immediately prior to the ownership change. Subsequent ownership changes may further affect the limitation in future years. The Company has completed several equity offerings since its inception which may have resulted in a change in control as defined by Sections 382 and 383 of the IRC, or could result in a change in control in the future. The Company has not completed an IRC Section 382 and 383 analysis regarding the limitation of net operating loss and research and development credit carryforwards. Until such an analysis has been completed, the Company has removed the deferred tax assets for net operating losses of $31.8 million and federal and California research and development credits of approximately $24.2 million from its deferred tax asset schedule, and has recorded a corresponding decrease to its valuation allowance. When this analysis is finalized, the Company plans to update its unrecognized tax benefits accordingly. The Company does not expect this analysis to be completed within the next 12 months and, as a result, the Company does not expect that the unrecognized tax benefits will change within 12 months of this reporting date. Due to the existence of the valuation allowance, future changes in the Company’s unrecognized tax benefits will not impact the Company’s effective tax rate. The Company’s policy is to record interest and penalties relating to uncertain tax positions as a component of income tax expense. As of December 31, 2017 and 2016, there was no accrued interest or penalties for uncertain tax positions. The Company is subject to taxation in the U.S. and state jurisdictions. As of December 31, 2017, the Company’s tax years beginning 2007 to date are subject to examination by federal and California taxing authorities due to the carry forward of unutilized net operating losses and research and development tax credits. To the extent the Company has tax attribute carryforwards, the tax years in which the attribute was generated may still be adjusted upon examination by the Internal Revenue Service or state tax authorities to the extent utilized in a future period. Pursuant to the federal tax legislation that was enacted on December 22, 2017 (the Tax Act), the Company re-measured its existing deferred tax assets and liabilities based on 21%, the current rate at which they are expected to reverse in the future. As of December 31, 2017, the Company recorded a provisional amount of $1.4 million relating to the re-measurement of its existing deferred tax asset balance, and it was fully offset by a decrease in its valuation allowance. As of December 31, 2017, the Company has not completed its accounting for the tax effects of enactment of the Tax Act and it will continue to refine its calculations as additional analysis is completed. The additional analysis could potentially affect the measurement of the Company’s existing deferred tax balances or potentially give rise to new deferred tax amounts. In addition, the Company’s estimates may also be affected as it gains a more thorough understanding of the tax law. |
Retirement Plan
Retirement Plan | 12 Months Ended |
Dec. 31, 2017 | |
Compensation And Retirement Disclosure [Abstract] | |
Retirement Plan | 11. Retirement Plan The Company sponsors an employee savings plan that qualifies as a deferred salary arrangement under Section 401(k) of the IRC. Participating employees may defer up to the Internal Revenue Service annual contribution limit. Additionally, the Company may elect to make contributions into the savings plan at its sole discretion. The Company has not made any contributions for the years ended December 31, 2017, 2016 and 2015. |
Commitments and Contingencies
Commitments and Contingencies | 12 Months Ended |
Dec. 31, 2017 | |
Commitments And Contingencies Disclosure [Abstract] | |
Commitments and Contingencies | 12. Commitments and Contingencies Leases and Other Commitments The Company leases its laboratory and office space under an operating lease. Rent expense under the lease was $0.4 million, $0.4 million, $0.3 million during the years ended December 31, 2017, 2016 and 2015, respectively. Future minimum obligations under all non-cancelable operating lease commitments at December 31, 2017 are $71,000 which is due during 2018. The existing operating lease of the Company for laboratory and office space was amended in March 2018 to provide for an extension of the lease term until June 30, 2018. Additionally, the Company will continue to lease approximately 2,000 square feet of its existing laboratory and office space through December 31, 2018. Future minimum obligations related to the extension of the existing lease are $0.2 million during 2018. On January 10, 2018, the Company entered into a new lease (New Lease) with a new landlord for the lease of approximately 39,000 square feet of laboratory and office space located at 4242 Campus Point Court, San Diego, California (New Premises). The commencement date of the New Lease will be the earlier of (a) June 1, 2018, (b) substantial completion of tenant improvements, or (c) the date the Company begins conducting business operations in all or any portion of the New Premises. The Company expects to use the New Premises as its new principal executive offices and for general office, research and development, lab and pilot manufacturing uses. The term of the New Lease is eight years and the Company has one option to extend the New Lease for a period of five additional years. The New Lease provides for an abatement of a portion of the lease payments for the first nine months of the lease term as well as a tenant improvement allowance of approximately $1.2 million. Future annual minimum rental payments payable under the New Lease are as follows (shown in thousands): Years ended December 31: 2018 $ 384 2019 1,802 2020 1,945 2021 2,013 2022 2,083 Thereafter 7,674 Total $ 15,901 The Company enters into service agreements with indemnification clauses in the ordinary course of business. Pursuant to such clauses, the Company indemnifies, defends, holds harmless, and agrees to reimburse the indemnified party for losses suffered or incurred by third party claims arising out of the indemnified party’s performance of service. The term of these indemnification clauses is perpetual any time after execution of the agreement. The maximum potential amount of future payments the Company could be required to make under these indemnification clauses is unlimited. The Company has not incurred costs to defend lawsuits pursuant to these indemnification clauses. Legal Proceedings From time to time, the Company may be involved in various claims and legal proceedings relating to claims arising out of the Company’s operations. The Company is not currently a party to any legal proceedings that, in the opinion of management, are likely to have a material adverse effect on the Company’s business. Regardless of outcome, litigation can have an adverse |
Selected Quarterly Financial Da
Selected Quarterly Financial Data (unaudited) | 12 Months Ended |
Dec. 31, 2017 | |
Quarterly Financial Information Disclosure [Abstract] | |
Selected Quarterly Financial Data (unaudited) | 13. Selected Quarterly Financial Data (unaudited) The following table contains unaudited quarterly financial information for the years ended December 31, 2017 and 2016. The Company believes that the following information reflects all normal recurring adjustments necessary for a fair statement of the information for the periods presented. The operating results for any quarter are not necessarily indicative of results for any future period. First Quarter Second Quarter Third Quarter Fourth Quarter Year Ended December 31, 2017 Operating expenses $ 8,564 $ 8,662 $ 9,747 $ 10,697 Net loss (9,073 ) (9,066 ) (9,953 ) (10,837 ) Net loss per common share, basic and diluted $ (4.11 ) $ (0.56 ) $ (0.50 ) $ (0.55 ) Year Ended December 31, 2016 Operating expenses $ 7,580 $ 7,633 $ 8,542 $ 7,985 Net loss (8,006 ) (8,042 ) (9,000 ) (8,430 ) Net loss per common share, basic and diluted $ (3.64 ) $ (3.66 ) $ (4.09 ) $ (3.83 ) |
Summary of Significant Accoun20
Summary of Significant Accounting Policies (Policies) | 12 Months Ended |
Dec. 31, 2017 | |
Accounting Policies [Abstract] | |
Use of Estimates | Use of Estimates The Company’s financial statements are prepared in accordance with accounting principles generally accepted in the United States (GAAP), which requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements, and expenses and related disclosures during the reporting period. Significant estimates in the Company’s financial statements relate to clinical trial accruals, the valuation of equity awards, and the development period used for license revenue recognition. Estimates are periodically reviewed in light of changes in circumstances, facts and experience. Actual results may differ from these estimates under different assumptions or conditions. |
Cash, Cash Equivalents and Marketable Securities | Cash, Cash Equivalents and Marketable Securities Cash consists of the balance in a readily available checking account. Cash equivalents consist of money market funds, repurchase agreements, corporate debt securities and certificates of deposit with remaining maturities of three months or less at the time of purchase, and are considered highly liquid investments. Marketable securities consist of corporate debt securities, certificates of deposit, commercial paper, asset-backed securities and U.S. Treasury securities that have original maturities greater than three months at the time of purchase. The Company classifies its investments as available-for-sale and records such assets at fair value in the balance sheet, with unrealized gains and losses, if any, reported in stockholders’ equity (deficit). Realized gains and losses are calculated on the specific identification method and recorded to interest income. A decline in the market value of any marketable security below cost that is determined to be other-than-temporary results in a revaluation of its carrying amount to fair value and a new cost basis for the security. Impairment losses are recognized in other expense in the statement of operations. |
Concentration of Credit Risk and Off-Balance Sheet Risk | Concentration of Credit Risk and Off-Balance Sheet Risk Financial instruments that potentially subject the Company to significant concentration of credit risk consist primarily of cash equivalents and marketable securities. The Company’s investment policy includes guidelines for the quality of the related institutions and financial instruments, and defines allowable investments that the Company may invest in, which the Company believes minimizes the exposure to concentration of credit risk. |
Prepaid Expenses and Other Current Assets | Prepaid Expenses and Other Current Assets Prepaid expenses and other current assets primarily represent amounts related to insurance, clinical trial and manufacturing agreements, and investment interest receivable. |
Property and Equipment | Property and Equipment Property and equipment consists of furniture, fixtures, computers and software, laboratory and office equipment, and leasehold improvements. Property and equipment is stated at cost and depreciated over the estimated useful lives of the assets (three to five years) using the straight-line method. Leasehold improvements are depreciated using the straight-line method over the lesser of the remaining lease term or an estimated useful life of five years. Costs of major additions and betterments are capitalized and depreciated on a straight-line basis over their useful lives. Repairs and maintenance costs are expensed as incurred. Upon retirement or sale, the cost of assets disposed of and the related accumulated depreciation are removed from the accounts, and any resulting gain or loss is credited or charged to expense. |
Deferred Equity Issuance Costs | Deferred Equity Issuance Costs Specific incremental costs directly attributable to a proposed or actual offering of securities are deferred and charged against the gross proceeds of the offering through additional paid-in capital. |
Impairment of Long-Lived Assets | Impairment of Long-Lived Assets Long-lived assets consist of property and equipment. An impairment loss is recorded if and when events and circumstances indicate that assets might be impaired and the undiscounted cash flows estimated to be generated by those assets are less than the carrying amount of those assets. |
Fair Value of Financial Instruments | Fair Value of Financial Instruments The Company’s financial instruments consist principally of cash, cash equivalents, marketable securities, accounts payable, notes payable, convertible promissory notes payable and preferred stock warrant liabilities. The authoritative 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 authoritative accounting guidance establishes a three-tier fair value hierarchy that 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 such as quoted prices for similar assets or liabilities, quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities; and Level 3: Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. |
Clinical Trial Accruals | Clinical Trial Accruals Expenses related to clinical studies are based on estimates of the services received and efforts expended pursuant to the Company’s contract arrangements. The financial terms of these agreements are subject to negotiation, vary from contract to contract and may result in uneven payment flows. There may be instances in which payments made to the Company’s service providers will temporarily exceed the level of services provided and result in a prepayment of the clinical expense. Payments under some of these contracts depend on factors such as the successful enrollment of patients, site initiation and the completion of clinical milestones. The Company makes estimates of its accrued expenses as of each balance sheet date in its financial statements based on facts and circumstances known at that time. In accruing service fees, the Company estimates the time period over which services will be performed and the level of effort to be expended in each period. If the actual timing of the performance of services or the level of effort varies from its estimate, the Company adjusts the accrual or prepaid expense balance accordingly. |
Revenue Recognition | Revenue Recognition Revenue is comprised of license revenue from the up-front payment that the Company received under its license and collaboration arrangement with Siemens Healthcare Diagnostics Inc. (Siemens). Revenue is recognized for each unit of accounting when all of the following criteria are met: • Persuasive evidence of an arrangement exists • Delivery of the Company’s obligations under the arrangement has occurred • The seller’s price to the buyer is fixed or determinable • Collectability is reasonably assured Amounts received prior to satisfying the revenue recognition criteria are recorded as deferred revenue in the Company’s balance sheets. Amounts expected to be recognized as revenue within the 12 months following the balance sheet date are classified as deferred revenue. Amounts not expected to be recognized as revenue within the 12 months following the balance sheet date are classified as long-term deferred revenue. The Company analyzes multiple-element arrangements based on the relevant authoritative guidance. Pursuant to the guidance, the Company evaluates multiple-element arrangements to determine (1) the deliverables included in the arrangement and (2) whether the individual deliverables represent separate units of accounting, or whether they must be accounted for as a combined unit of accounting. This evaluation involves subjective determinations and requires the Company to make judgments about the individual deliverables and whether such deliverables are separable from the other aspects of the contractual relationship. Deliverables are considered separate units of accounting provided that: (i) the delivered item(s) has value to the customer (a collaboration partner to date) on a standalone basis and (ii) if the arrangement includes a general right of return relative to the delivered item(s), delivery or performance of the undelivered item(s) is considered probable and substantially in its control. In assessing whether an item has standalone value, the Company considers factors such as the research, manufacturing and commercialization capabilities of the collaboration partner and the availability of the associated expertise in the general marketplace. In addition, the Company considers whether the collaboration partner can use the other deliverable(s) for their intended purpose without the receipt of the remaining element(s), whether the value of the deliverable is dependent on the undelivered item(s) and whether there are other vendors that can provide the undelivered element(s). Arrangement consideration that is fixed or determinable is allocated among the separate units of accounting using the relative selling price method. The Company determines the estimated selling price for units of accounting within each arrangement using vendor-specific objective evidence (VSOE) of selling price, if available, third-party evidence (TPE) of selling price if VSOE is not available, or best estimate of selling price (BESP) if neither VSOE nor TPE is available. The Company uses BESP to estimate the selling price, since it generally does not have VSOE or TPE of selling price for its units of accounting. Determining the BESP for a unit of accounting requires significant judgment. In developing the BESP for a unit of accounting, the Company considers applicable market conditions and relevant entity-specific factors, including factors that were contemplated in negotiating the agreement with the collaboration partner and estimated costs. The Company validates the BESP for units of accounting by evaluating whether changes in the key assumptions used to determine the BESP will have a significant effect on the allocation of arrangement consideration between multiple units of accounting. The Company then applies the applicable revenue recognition criteria to each of the separate units of accounting in determining the appropriate period and pattern of recognition. If there is no discernible pattern of performance and/or objectively measurable performance measures do not exist, then the Company recognizes revenue under the arrangement on a straight-line basis over the period it expects to complete its performance obligations. |
Research and Development Costs | Research and Development Costs Research and development expenses consist primarily of salaries and other personnel related expenses including stock-based compensation costs, preclinical costs, clinical trial costs, costs related to acquiring and manufacturing clinical trial materials, contract services, facilities costs, overhead costs, and depreciation. All research and development costs are expensed as incurred. |
Patent Costs | Patent Costs Costs related to filing and pursuing patent applications are recorded as general and administrative expense and expensed as incurred because recoverability of such expenditures is uncertain. |
Grant Funding | Grant Funding The Company receives certain research and development funding through grants from nonprofit organizations that serve the brain cancer community. The Company evaluates the terms of each grant to assess the Company’s obligations, and such funding is recognized in the statement of operations as a reduction to research and development expense as the related costs are incurred to meet those obligations over the grant period. Certain grants contain repayment provisions contingent on future events, such as future revenue milestones related to the Company’s lead product candidate under development. For each repayment provision, the Company assesses if it is obligated to repay the funds provided by the other parties regardless of the outcome of the funded research and development. For each arrangement, the Company also reviews the repayment provisions to determine the likelihood of repayment at the execution of each grant and on an ongoing basis. If the likelihood of repayment of a grant is determined to be remote and the Company is not obligated to repay the funds regardless of the outcome of the funded research and development, the grant is recognized as a reduction to research and development expense as related costs are incurred over the grant period. The Company subsequently reviews the repayment provisions of each grant at each reporting date and will record a related grant repayment liability if and when such repayment obligation is determined to be probable. If, at the execution of a grant with repayment provisions, the probability of repayment is probable, the Company will record the grant as a liability until such time as the grant requirements have been satisfied and the repayment provisions have lapsed. |
Debt Issuance Costs | Debt Issuance Costs Debt issuance costs incurred to obtain debt financing are deferred and are amortized over the term of the debt using the effective interest method. The costs are recorded as a reduction to the carrying value of the debt and the amortization expense is included in interest expense in the statement of operations. |
Warrants for Shares of Preferred Stock | Warrants for Shares of Preferred Stock The Company accounts for warrants for shares of preferred stock with conversion features as liabilities in the accompanying balance sheets at their fair value on the date of issuance. The warrant liabilities are revalued at each balance sheet date until such instruments are exercised or expire, with changes in the fair value between reporting periods recorded as other income or expense in the statement of operations. All preferred stock warrant liabilities were reclassified to equity in connection with the IPO. |
Income Taxes | Income Taxes The Company accounts for income taxes under the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences that have been included in the financial statements. Under this method, deferred tax assets and liabilities are determined on the basis of the differences between the financial statements and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. The Company provides a valuation allowance against net deferred tax assets unless, based upon the available evidence, it is more likely than not that the deferred tax assets will be realized. The Company records uncertain tax positions on the basis of a two-step process whereby (i) management determines whether it is more likely than not that the tax positions will be sustained on the basis of the technical merits of the position and (ii) for those tax positions that meet the more likely-than-not recognition threshold, management recognizes the largest amount of tax benefit that is more than 50 percent likely to be realized upon ultimate settlement with the related tax authority. The Company will recognize interest and penalties in income tax expense if and when incurred. |
Comprehensive Income (Loss) | Comprehensive Income (Loss) All components of comprehensive income (loss) are reported in the financial statements in the period in which they are recognized. Other comprehensive income (loss) is defined as the change in equity during a period from transactions and other events and circumstances from non-owner sources, including unrealized gains and losses on investments. The Company’s only component of other comprehensive loss is unrealized gains (losses) on investments. Comprehensive gains (losses) have been reflected in the statements of operations and comprehensive loss for all periods presented. |
Stock-Based Compensation | Stock-Based Compensation Stock-based compensation expense represents the cost of the grant date fair value of stock awards, including stock options, and stock purchase rights granted to employees. For awards with time-based vesting provisions, the Company estimates the fair value of stock options on the date of grant using the Black-Scholes option pricing model and recognizes the expense over the requisite service period of the awards, which is generally the vesting period, on a straight-line basis. For awards with performance-based vesting provisions, the Company estimates the fair value of stock option grants on the date of grant, or the date when all of the terms of the grant have been agreed to, if later, and recognizes the expense based on the probability of the occurrence of the individual milestones at each reporting period. The expense is recognized over the implicit service period that commences once management believes the performance criteria are probable of being met. For purchase rights, the Company estimates the fair value of the purchase as of the plan enrollment date and recognizes expense on a straight-line basis over the applicable offering period. The Company accounts for forfeitures when they occur, and reverses any compensation cost previously recognized for awards for which the requisite service has not been completed, in the period that the award is forfeited. The Company accounts for stock options and stock warrants granted to non-employees using the fair value approach. These option and warrant grants are subject to periodic revaluation over their vesting terms. |
Net Loss Per Share | Net Loss Per Share Basic and diluted net loss per common share for the periods presented is computed by dividing net loss by the weighted-average number of common shares outstanding during the respective periods, without consideration of common stock equivalents as they are anti-dilutive. Common stock equivalents that could potentially dilute earnings in the future are comprised of shares issuable upon the conversion of all outstanding principal and accrued interest related to convertible promissory notes payable, shares issuable upon the conversion of convertible preferred stock, options to purchase shares of common stock outstanding under the Company’s equity incentive plan and warrants for the purchase of shares of common and preferred stock. For all periods presented, there is no difference in the number of shares used to calculate basic and diluted shares outstanding due to the Company’s net loss position. Common stock equivalents from potentially dilutive securities, excluding shares issuable upon the conversion of all outstanding principal and accrued interest related to convertible promissory notes, that are not included in the calculation of diluted net loss per share, because to do so would be anti-dilutive, are as follows: Years Ended December 31, 2017 2016 2015 Common stock options 2,589,348 1,385,855 738,809 Common stock warrants 10,660 724 724 Convertible preferred stock (as-converted) — 6,690,066 6,690,066 Convertible preferred stock warrants (as-converted) — 9,936 9,936 Total 2,600,008 8,086,581 7,439,535 |
Recent Accounting Pronouncements | Recent Accounting Pronouncements In May 2014, the Financial Accounting Standards Board (FASB) issued new revenue recognition guidance which outlines a single comprehensive revenue model for entities to use in accounting for revenue arising from contracts with customers. The guidance supersedes most current revenue recognition guidance, including industry-specific guidance. The guidance provides that an entity recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The guidance will be effective on January 1, 2018. The guidance allows for either a full retrospective adoption, in which the standard is applied to all of the periods presented, or a modified retrospective adoption, in which the standard is applied to the most current period presented in the financial statements. As of December 31, 2017, revenue has been generated exclusively from the Company’s license and collaboration arrangement with Siemens. The Company has completed its evaluation of the impact that this guidance has on its financial position and results of operations as it relates to this single arrangement, and has elected the modified retrospective adoption method. Overall, the Company does not expect the timing of revenue recognition under the new standards to be materially different from the Company’s current revenue recognition policy. Based on the Company’s analysis of the open contract as of December 31, 2017, the cumulative effect of applying the new standards is not material. The Company is finalizing the new required disclosures. In January 2016, the FASB issued guidance that amends certain aspects of the recognition, measurement, presentation and disclosure of financial instruments. The amendments include the elimination of the available-for-sale classification of equity investments and requires equity investments with readily determinable fair values to be measured at fair value with changes in fair value recognized in net income (loss). The guidance is effective for fiscal years and interim periods within those years beginning after December 15, 2017, and requires a cumulative-effect adjustment to the balance sheet as of the beginning of the fiscal year of adoption. Early adoption is not permitted. The Company’s marketable securities are currently accounted for as available-for-sale financial instruments with changes in fair value recognized in other comprehensive income (loss). At the time of adoption, any amounts in accumulated other comprehensive income (loss) related to such financial instruments would be reclassified to non-operating income (expense) in the statement of operations. As of December 31, 2017, a net unrealized loss of $34,000 related to these investments was recorded in accumulated other comprehensive loss in the accompanying balance sheet. In February 2016, the FASB issued accounting guidance that amends the existing accounting standards for leases. Under the guidance, lessees will be required to recognize for all leases, with the exception of short-term leases, a lease liability, which is a lessee’s obligation to make lease payments arising from a lease, measured on a discounted basis and a right-of-use asset, which is an asset that represents the lessee’s right to use, or control the use of, a specified asset for the lease term. The standard is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Early adoption is permitted. The Company is still in the process of evaluating the effect of adoption on its financial statements and expects to adopt the standard on January 1, 2019. The adoption will lead to an increase in the assets and liabilities recorded on the balance sheets primarily due to the lease agreement attributable to leased lab and office space. |
Summary of Significant Accoun21
Summary of Significant Accounting Policies (Tables) | 12 Months Ended |
Dec. 31, 2017 | |
Accounting Policies [Abstract] | |
Schedule of Common Stock Equivalents from Potentially Dilutive Securities Not Included in Calculation of Diluted Net Loss Per Share | Common stock equivalents from potentially dilutive securities, excluding shares issuable upon the conversion of all outstanding principal and accrued interest related to convertible promissory notes, that are not included in the calculation of diluted net loss per share, because to do so would be anti-dilutive, are as follows: Years Ended December 31, 2017 2016 2015 Common stock options 2,589,348 1,385,855 738,809 Common stock warrants 10,660 724 724 Convertible preferred stock (as-converted) — 6,690,066 6,690,066 Convertible preferred stock warrants (as-converted) — 9,936 9,936 Total 2,600,008 8,086,581 7,439,535 |
Fair Value of Financial Instr22
Fair Value of Financial Instruments (Tables) | 12 Months Ended |
Dec. 31, 2017 | |
Fair Value Disclosures [Abstract] | |
Summary of Fair Values of Assets and Liabilities Measured on a Recurring Basis | The following tables summarize the Company’s assets and liabilities that require fair value measurements on a recurring basis and their respective input levels based on the fair value hierarchy (in thousands): Fair Value Measurements at End of Period Using: Total Quoted Market Prices for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) December 31, 2017 Cash equivalents: Corporate debt securities $ 8,274 $ — $ 8,274 $ — Repurchase agreements 5,000 — 5,000 — $ 13,274 $ — $ 13,274 $ — Marketable securities: Corporate debt securities $ 24,713 $ — $ 24,713 $ — Certificates of deposit 13,651 — 13,651 — Commercial paper 12,329 — 12,329 — Asset-backed securities 2,099 — 2,099 — $ 52,792 $ — $ 52,792 $ — Fair Total Quoted Market Prices for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) December 31, 2016 Cash equivalents: Certificates of deposit $ 240 $ — $ 240 $ — Marketable securities: Certificates of deposit $ 22,777 $ — $ 22,777 $ — U.S. Treasury securities 2,958 2,958 — — $ 25,735 $ 2,958 $ 22,777 $ — Preferred stock warrant liabilities $ 126 $ — $ — $ 126 |
Summary of Activity in Liabilities Measured at Fair Value on Recurring Basis | The following table summarizes the activity in liabilities measured at fair value on a recurring basis using significant unobservable inputs (Level 3 inputs) (in thousands): Preferred Stock Warrant Liabilities Balance at December 31, 2015 $ 176 Gain on warrant valuation included in other income (expense), net (50 ) Balance at December 31, 2016 126 Gain on warrant valuation included in other income (expense), net (37 ) Conversion of preferred stock warrant liabilities into warrants to purchase shares of common stock (89 ) Balance at December 31, 2017 $ — |
Schedule of Future Annual Minimum Rental Payments Payable Under New Lease | Future annual minimum rental payments payable under the New Lease are as follows (shown in thousands): Years ended December 31: 2018 $ 384 2019 1,802 2020 1,945 2021 2,013 2022 2,083 Thereafter 7,674 Total $ 15,901 |
Certain Financial Statement C23
Certain Financial Statement Caption Information (Tables) | 12 Months Ended |
Dec. 31, 2017 | |
Balance Sheet Related Disclosures [Abstract] | |
Summary of Marketable Securities | The following is a summary of the Company’s marketable securities (in thousands): Maturity (in years) Amortized Cost Unrealized Gain Unrealized Loss Fair Value December 31, 2017: Corporate debt securities 1 or less $ 21,097 $ — $ (16 ) $ 21,081 Corporate debt securities >1 and <5 3,636 — (4 ) 3,632 Certificates of deposit 1 or less 13,658 — (7 ) 13,651 Commercial paper 1 or less 12,333 — (4 ) 12,329 Asset-backed securities 1 or less 2,099 — — 2,099 $ 52,823 $ — $ (31 ) $ 52,792 December 31, 2016: Certificates of deposit 1 or less $ 19,299 $ 1 $ (2 ) $ 19,298 Certificates of deposit >1 and <5 3,478 1 — 3,479 U.S. Treasury securities 1 or less 1,678 — — 1,678 U.S. Treasury securities >1 and <5 1,280 4 (4 ) 1,280 $ 25,735 $ 6 $ (6 ) $ 25,735 |
Summary of Property and Equipment | Property and equipment is comprised of (in thousands): December 31, 2017 2016 Laboratory equipment $ 3,553 $ 2,841 Computers, software and office equipment 232 187 Furniture and fixtures 21 21 Leasehold improvements 117 108 3,923 3,157 Less: accumulated depreciation (2,706 ) (2,414 ) $ 1,217 $ 743 |
Components of Accrued Liabilities | Accrued liabilities are comprised of (in thousands): December 31, 2017 2016 Clinical trial expenses $ 2,809 $ 2,196 Payroll and other employee-related expenses 2,489 728 Contract manufacturing services 1,536 1,508 Professional fees 276 459 Contract research services 104 114 Interest payable 77 120 Other 829 312 Total accrued liabilities $ 8,120 $ 5,437 |
Notes Payable (Tables)
Notes Payable (Tables) | 12 Months Ended |
Dec. 31, 2017 | |
Debt Disclosure [Abstract] | |
Schedule of Aggregate Carrying Amounts of Loans | The aggregate carrying amounts of the Loans are comprised of the following (in thousands): December 31, 2017 2016 Principal $ 10,200 $ 17,400 Add: accreted liability for final payment fee 869 462 Less: unamortized discount (244 ) (421 ) $ 10,825 $ 17,441 |
Schedule of Future Maturities Loans Including Final Payment Fee | Future maturities of the Loans, including the final payment fee, as of December 31, 2017 are as follows (in thousands): December 31, 2017 Year ending December 31, 2018 $ 7,200 Year ending December 31, 2019 4,431 11,631 Unaccreted balance for final payment fee on Loans (562 ) Unamortized discounts (244 ) 10,825 Less current portion (7,200 ) Noncurrent portion $ 3,625 |
Stockholders' Equity (Deficit)
Stockholders' Equity (Deficit) (Tables) | 12 Months Ended |
Dec. 31, 2017 | |
Equity [Abstract] | |
Schedule of Common Stock Reserved for Future Issuance | Common stock reserved for future issuance at December 31, 2017 and 2016 is as follows and for 2016 excludes shares issued upon conversion of all outstanding principal and accrued interest related to the convertible promissory notes payable upon completion of the Company’s IPO on April 19, 2017: December 31, 2017 2016 Issued and Outstanding: Stock options 2,589,348 1,385,855 Warrants for common stock 10,660 724 Shares reserved for issuance under the ESPP 199,879 — Shares reserved for future award grants 513,333 172,495 Conversion of all outstanding convertible preferred stock — 6,690,070 Conversion of preferred stock warrants issued and outstanding — 9,936 |
Equity Incentive Plan and Stock
Equity Incentive Plan and Stock-Based Compensation (Tables) | 12 Months Ended |
Dec. 31, 2017 | |
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract] | |
Summary of Stock Option Activity | The following table summarizes stock option activity under the 2009 Plan and the 2017 Plan: Shares Subject to Options Weighted- Average Exercise Price per Share Weighted- Average Remaining Contractual Term (in years) Aggregate Intrinsic Value (in thousands) Outstanding at December 31, 2016 1,385,855 $ 11.35 Granted 1,400,245 $ 14.92 Exercised (55,669 ) $ 1.45 Forfeitures and cancellations (141,083 ) $ 14.39 Outstanding at December 31, 2017 2,589,348 $ 13.33 8.1 $ 2,643 Time-based options at December 31, 2017: Outstanding 2,400,697 $ 13.09 8.1 $ 2,643 Vested and expected to vest 2,400,697 $ 13.09 8.1 $ 2,643 Exercisable 742,213 $ 8.68 5.6 $ 2,602 Performance-based options at December 31, 2017: Outstanding 188,651 $ 16.30 8.9 — Vested and expected to vest — — — — Exercisable — — — — |
Summary of Information Regarding Stock Options | The following table summarizes certain information regarding stock options (in thousands): Years Ended December 31, 2017 2016 2015 Fair value of options vested during the period $ 2,194 $ 1,087 $ 862 Cash received from options exercised during the period $ 81 $ 10 $ 157 Intrinsic value of options exercised during the period $ 677 $ 62 $ 160 |
Summary of Fair Value of Employee Stock Option Grants with Both Time-Based and Performance-Based Vesting Provisions and Stock Purchase Rights | The assumptions used in the Black-Scholes option pricing model to determine the fair value of the employee stock option grants with both time-based and performance-based vesting provisions and stock purchase rights were as follows: Years Ended December 31, 2017 2016 2015 Time-Based Vesting Provisions Performance-Based Vesting Provisions ESPP Purchase Rights Time-Based Vesting Provisions Risk-free interest rate 1.83% - 2.27% 1.98% - 2.17% 1.04% - 1.82% 1.63% 1.61% Expected volatility 75.9% - 87.5% 75.2% - 76.3% 65.7% - 84.4% 73.3% - 73.5% 73.5% - 86.8% Weighted-average volatility 82.2% 75.9% 69.6% 73.4% 82.2% Dividend yield 0% 0% 0% 0% 0% Weighted-average expected term (in years) 6.1 6.3 1.3 6.1 6.1 Weighted-average grant date fair value per share $ 10.39 $ 6.73 $ 4.61 $ 9.69 $ 13.56 |
Summary of Total Non-Cash Stock-Based Compensation Expense for All Stock Awards and Purchase Rights, Net of Forfeitures Recognized | Total non-cash stock-based compensation expense for all stock awards and purchase rights, net of forfeitures recognized as they occur, that was recognized in the statements of operations is as follows (in thousands): Years Ended December 31, 2017 2016 2015 Research and development $ 1,783 $ 562 $ 456 General and administrative 2,668 761 606 Total $ 4,451 $ 1,323 $ 1,062 |
Income Taxes (Tables)
Income Taxes (Tables) | 12 Months Ended |
Dec. 31, 2017 | |
Income Tax Disclosure [Abstract] | |
Reconciliation of U.S. Statutory Federal Income Tax Rate | The (benefit) provision for income taxes differs from the amount of income tax determined by applying the applicable U.S. statutory federal income tax rate to pretax income as a result of the following differences: Years Ended December 31, 2017 2016 2015 Federal statutory rate 34.0 % 34.0 % 34.0 % Adjustments for tax effects of: State taxes, net 5.7 % 5.6 % 5.6 % Permanent adjustments (4.5 )% (5.4 )% (4.8 )% Tax Cuts and Jobs Act (3.7 )% — % — % Net operating loss carryovers not recognized (30.4 )% (32.8 )% (33.3 )% Valuation allowance (1.0 )% (1.1 )% (1.7 )% Other (0.1 )% (0.3 )% 0.2 % Effective income tax rate — % — % — % |
Components of Deferred Taxes | Deferred taxes are recognized for temporary differences between the basis of assets and liabilities for financial statement and income tax purposes. Significant components of the Company’s deferred taxes are as follows (in thousands): December 31, 2017 2016 Deferred tax assets: Depreciation and amortization $ 52 $ 52 Deferred license revenue 15 38 Share-based compensation 1,459 1,062 Accrued liabilities and other 808 796 Total deferred tax assets 2,334 1,948 Less valuation allowance (2,334 ) (1,948 ) Net deferred tax assets $ — $ — |
Selected Quarterly Financial 28
Selected Quarterly Financial Data (unaudited) (Tables) | 12 Months Ended |
Dec. 31, 2017 | |
Quarterly Financial Information Disclosure [Abstract] | |
Unaudited Quarterly Financial Information | The following table contains unaudited quarterly financial information for the years ended December 31, 2017 and 2016. The Company believes that the following information reflects all normal recurring adjustments necessary for a fair statement of the information for the periods presented. The operating results for any quarter are not necessarily indicative of results for any future period. First Quarter Second Quarter Third Quarter Fourth Quarter Year Ended December 31, 2017 Operating expenses $ 8,564 $ 8,662 $ 9,747 $ 10,697 Net loss (9,073 ) (9,066 ) (9,953 ) (10,837 ) Net loss per common share, basic and diluted $ (4.11 ) $ (0.56 ) $ (0.50 ) $ (0.55 ) Year Ended December 31, 2016 Operating expenses $ 7,580 $ 7,633 $ 8,542 $ 7,985 Net loss (8,006 ) (8,042 ) (9,000 ) (8,430 ) Net loss per common share, basic and diluted $ (3.64 ) $ (3.66 ) $ (4.09 ) $ (3.83 ) |
Organization and Basis of Pre29
Organization and Basis of Presentation - Additional Information (Details) $ / shares in Units, $ in Thousands | Apr. 19, 2017USD ($)$ / sharesshares | Dec. 31, 2017USD ($)Segment | Dec. 31, 2016USD ($) | Dec. 31, 2015USD ($) |
Organization Consolidation And Presentation Of Financial Statements [Line Items] | ||||
Completion date of initial public offering | April 19, 2017 | |||
Net proceeds from issuance of initial public offering | $ 86,900 | |||
Payments for underwriting discounts, commissions and estimated offering costs | $ 592 | $ 982 | ||
Conversion of convertible promissory notes into common stock | shares | 1,109,176 | |||
Conversion of convertible promissory notes price, per share | $ / shares | $ 10 | |||
Accumulated deficit | $ 166,929 | $ 128,000 | ||
Working capital | $ 73,300 | |||
Number of operating segment | Segment | 1 | |||
IPO | ||||
Organization Consolidation And Presentation Of Financial Statements [Line Items] | ||||
Common stock issued, shares | shares | 9,775,000 | |||
Shares price, per share | $ / shares | $ 10 | |||
Stock issuance costs incurred for underwriting discounts, commissions and estimated offering costs | $ 10,800 | |||
Payments for underwriting discounts, commissions and estimated offering costs | $ 9,100 | |||
Outstanding shares of convertible preferred stock converted into common stock, shares | shares | 6,690,066 | |||
Warrant to purchase common stock, exercise price | $ / shares | $ 36.23 | |||
Aggregate principal and accrued interest, convertible promissory notes amount | $ 11,100 | |||
Conversion of convertible promissory notes into common stock | shares | 1,109,176 | |||
Conversion of convertible promissory notes price, per share | $ / shares | $ 10 | |||
IPO | Maximum | ||||
Organization Consolidation And Presentation Of Financial Statements [Line Items] | ||||
Warrants to purchase shares of common stock | shares | 9,936 | |||
IPO | Maximum | Series H Convertible Preferred Stock | ||||
Organization Consolidation And Presentation Of Financial Statements [Line Items] | ||||
Warrants to purchase shares of common stock | shares | 68,572 |
Summary of Significant Accoun30
Summary of Significant Accounting Policies - Additional Information (Details) - USD ($) | 12 Months Ended | ||
Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | |
Schedule Of Significant Accounting Policies [Line Items] | |||
Income tax position likely of being realized upon ultimate settlement | more than 50 percent | ||
Net unrealized loss on investments | $ (34,000) | $ 58,000 | $ (52,000) |
Minimum | |||
Schedule Of Significant Accounting Policies [Line Items] | |||
Property and equipment, estimated useful life | 3 years | ||
Maximum | |||
Schedule Of Significant Accounting Policies [Line Items] | |||
Property and equipment, estimated useful life | 5 years | ||
Leasehold Improvements | |||
Schedule Of Significant Accounting Policies [Line Items] | |||
Property and equipment, estimated useful life | 5 years | ||
Property and equipment, estimated useful life description | Leasehold improvements are depreciated using the straight-line method over the lesser of the remaining lease term or an estimated useful life of five years. |
Summary of Significant Accoun31
Summary of Significant Accounting Policies - Schedule of Common Stock Equivalents from Potentially Dilutive Securities Not Included in Calculation of Diluted Net Loss Per Share (Details) - shares | 12 Months Ended | ||
Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | |
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items] | |||
Potential dilutive securities not included in calculation of diluted net loss per share | 2,600,008 | 8,086,581 | 7,439,535 |
Common Stock Options | |||
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items] | |||
Potential dilutive securities not included in calculation of diluted net loss per share | 2,589,348 | 1,385,855 | 738,809 |
Common Stock Warrants | |||
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items] | |||
Potential dilutive securities not included in calculation of diluted net loss per share | 10,660 | 724 | 724 |
Convertible Preferred Stock Warrants (as-converted) | |||
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items] | |||
Potential dilutive securities not included in calculation of diluted net loss per share | 9,936 | 9,936 | |
Convertible Preferred Stock (as-converted) | |||
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items] | |||
Potential dilutive securities not included in calculation of diluted net loss per share | 6,690,066 | 6,690,066 |
Fair Value of Financial Instr32
Fair Value of Financial Instruments - Summary of Fair Value of Assets and Liabilities Measured on a Recurring Basis (Details) - Fair Value Measured on Recurring Basis - USD ($) $ in Thousands | Dec. 31, 2017 | Dec. 31, 2016 |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] | ||
Cash equivalents | $ 13,274 | |
Marketable securities | 52,792 | $ 25,735 |
Preferred Stock Warrant | ||
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] | ||
Preferred stock warrant liabilities | 126 | |
Repurchase Agreements | ||
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] | ||
Cash equivalents | 5,000 | |
Quoted Market Prices for Identical Assets (Level 1) | ||
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] | ||
Marketable securities | 2,958 | |
Significant Other Observable Inputs (Level 2) | ||
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] | ||
Cash equivalents | 13,274 | |
Marketable securities | 52,792 | 22,777 |
Significant Other Observable Inputs (Level 2) | Repurchase Agreements | ||
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] | ||
Cash equivalents | 5,000 | |
Significant Unobservable Inputs (Level 3) | Preferred Stock Warrant | ||
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] | ||
Preferred stock warrant liabilities | 126 | |
Corporate Debt Securities | ||
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] | ||
Cash equivalents | 8,274 | |
Marketable securities | 24,713 | |
Corporate Debt Securities | Significant Other Observable Inputs (Level 2) | ||
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] | ||
Cash equivalents | 8,274 | |
Marketable securities | 24,713 | |
Certificates of Deposit | ||
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] | ||
Cash equivalents | 240 | |
Marketable securities | 13,651 | 22,777 |
Certificates of Deposit | Significant Other Observable Inputs (Level 2) | ||
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] | ||
Cash equivalents | 240 | |
Marketable securities | 13,651 | 22,777 |
U.S. Treasury Securities | ||
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] | ||
Marketable securities | 2,958 | |
U.S. Treasury Securities | Quoted Market Prices for Identical Assets (Level 1) | ||
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] | ||
Marketable securities | $ 2,958 | |
Commercial Paper | ||
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] | ||
Marketable securities | 12,329 | |
Commercial Paper | Significant Other Observable Inputs (Level 2) | ||
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] | ||
Marketable securities | 12,329 | |
Asset-backed Securities | ||
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] | ||
Marketable securities | 2,099 | |
Asset-backed Securities | Significant Other Observable Inputs (Level 2) | ||
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] | ||
Marketable securities | $ 2,099 |
Fair Value of Financial Instr33
Fair Value of Financial Instruments - Additional Information (Details) - USD ($) | Dec. 31, 2017 | Dec. 31, 2016 |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] | ||
Investments, transfer of Level 1 to Level 2 | $ 0 | $ 0 |
Carrying Amount | Significant Unobservable Inputs (Level 3) | ||
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] | ||
Notes payable | 10,800,000 | |
Money Market Funds | ||
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] | ||
Investments in money market funds measured at fair value using net asset value per share | $ 20,200,000 | $ 2,200,000 |
Fair Value of Financial Instr34
Fair Value of Financial Instruments - Summary of Activity in Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands | 12 Months Ended | |
Dec. 31, 2017 | Dec. 31, 2016 | |
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items] | ||
Conversion of preferred stock warrants to purchase shares of common stock | $ (89) | |
Preferred Stock Warrant Liabilities | ||
Fair Value Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Line Items] | ||
Beginning Balance | 126 | $ 176 |
Gain on warrant valuation included in other income (expense), net | (37) | (50) |
Conversion of preferred stock warrants to purchase shares of common stock | (89) | |
Ending Balance | $ 0 | $ 126 |
Certain Financial Statement C35
Certain Financial Statement Caption Information - Summary of Marketable Securities (Details) - USD ($) $ in Thousands | Dec. 31, 2017 | Dec. 31, 2016 |
Schedule Of Available For Sale Securities [Line Items] | ||
Amortized Cost | $ 52,823 | $ 25,735 |
Unrealized Gain | 6 | |
Unrealized Loss | (31) | (6) |
Fair Value | 52,792 | 25,735 |
Corporate Debt Securities | Maturity (in years) 1 or Less | ||
Schedule Of Available For Sale Securities [Line Items] | ||
Amortized Cost | 21,097 | |
Unrealized Loss | (16) | |
Fair Value | 21,081 | |
Corporate Debt Securities | Maturity More Than 1 Year and Less Than 5 Years | ||
Schedule Of Available For Sale Securities [Line Items] | ||
Amortized Cost | 3,636 | |
Unrealized Loss | (4) | |
Fair Value | 3,632 | |
Certificates of Deposit | Maturity (in years) 1 or Less | ||
Schedule Of Available For Sale Securities [Line Items] | ||
Amortized Cost | 13,658 | 19,299 |
Unrealized Gain | 1 | |
Unrealized Loss | (7) | (2) |
Fair Value | 13,651 | 19,298 |
Certificates of Deposit | Maturity More Than 1 Year and Less Than 5 Years | ||
Schedule Of Available For Sale Securities [Line Items] | ||
Amortized Cost | 3,478 | |
Unrealized Gain | 1 | |
Fair Value | 3,479 | |
Commercial Paper | Maturity (in years) 1 or Less | ||
Schedule Of Available For Sale Securities [Line Items] | ||
Amortized Cost | 12,333 | |
Unrealized Loss | (4) | |
Fair Value | 12,329 | |
Asset-backed Securities | Maturity (in years) 1 or Less | ||
Schedule Of Available For Sale Securities [Line Items] | ||
Amortized Cost | 2,099 | |
Fair Value | $ 2,099 | |
U.S. Treasury Securities | Maturity (in years) 1 or Less | ||
Schedule Of Available For Sale Securities [Line Items] | ||
Amortized Cost | 1,678 | |
Fair Value | 1,678 | |
U.S. Treasury Securities | Maturity More Than 1 Year and Less Than 5 Years | ||
Schedule Of Available For Sale Securities [Line Items] | ||
Amortized Cost | 1,280 | |
Unrealized Gain | 4 | |
Unrealized Loss | (4) | |
Fair Value | $ 1,280 |
Certain Financial Statement C36
Certain Financial Statement Caption Information - Additional Information (Details) - USD ($) | 12 Months Ended | ||
Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | |
Balance Sheet Related Disclosures [Abstract] | |||
Other-than-temporary impairments during period | $ 0 | ||
Depreciation | $ 292,000 | $ 255,000 | $ 232,000 |
Certain Financial Statement C37
Certain Financial Statement Caption Information - Summary of Property and Equipment (Details) - USD ($) $ in Thousands | Dec. 31, 2017 | Dec. 31, 2016 |
Property Plant And Equipment [Line Items] | ||
Property and equipment, gross | $ 3,923 | $ 3,157 |
Less: accumulated depreciation | (2,706) | (2,414) |
Property and equipment, net | 1,217 | 743 |
Laboratory Equipment | ||
Property Plant And Equipment [Line Items] | ||
Property and equipment, gross | 3,553 | 2,841 |
Computers, Software and Office Equipment | ||
Property Plant And Equipment [Line Items] | ||
Property and equipment, gross | 232 | 187 |
Furniture and Fixtures | ||
Property Plant And Equipment [Line Items] | ||
Property and equipment, gross | 21 | 21 |
Leasehold Improvements | ||
Property Plant And Equipment [Line Items] | ||
Property and equipment, gross | $ 117 | $ 108 |
Certain Financial Statement C38
Certain Financial Statement Caption Information - Components of Accrued Liabilities (Details) - USD ($) $ in Thousands | Dec. 31, 2017 | Dec. 31, 2016 |
Balance Sheet Related Disclosures [Abstract] | ||
Clinical trial expenses | $ 2,809 | $ 2,196 |
Payroll and other employee-related expenses | 2,489 | 728 |
Contract manufacturing services | 1,536 | 1,508 |
Professional fees | 276 | 459 |
Contract research services | 104 | 114 |
Interest payable | 77 | 120 |
Other | 829 | 312 |
Total accrued liabilities | $ 8,120 | $ 5,437 |
Notes Payable - Additional Info
Notes Payable - Additional Information (Details) | Apr. 19, 2017USD ($)$ / sharesshares | Oct. 30, 2015USD ($)Lender | Mar. 31, 2017USD ($) | Dec. 31, 2017USD ($) | Dec. 31, 2016USD ($) |
Debt Instrument [Line Items] | |||||
Proceeds from convertible promissory notes | $ 7,338,000 | $ 3,374,000 | |||
Convertible promissory notes subscription liability | 140,000 | ||||
Aggregate carrying amounts of the convertible notes | $ 3,398,000 | ||||
Aggregate carrying amounts of the convertible notes | $ 11,100,000 | ||||
Debt conversion, converted instrument, shares issued | shares | 1,109,176 | ||||
Debt instrument, conversion price | $ / shares | $ 10 | ||||
Loan Agreement | |||||
Debt Instrument [Line Items] | |||||
Number of Lenders | Lender | 2 | ||||
Loans | $ 18,000,000 | ||||
Floating rate of interest | 8.75% | 8.00% | |||
Debt instrument, interest rate terms | Loan Agreement bear a floating rate of interest equal to the greater of 7.75% or the monthly prime rate plus 4.50% | ||||
Debt instrument, frequency of periodic payment | due in monthly principal and interest payments, with final maturity of the Loans in May 2019. | ||||
Debt instrument maturity | May 31, 2019 | ||||
Debt instrument, final payment fee, percentage | 7.95% | ||||
Deferred debt issuance cost | $ 600,000 | ||||
Final payment fee | $ 1,400,000 | ||||
Debt instrument effective interest rate | 11.94% | 11.19% | |||
Loan Agreement | Minimum | |||||
Debt Instrument [Line Items] | |||||
Debt instrument, interest rate, stated percentage | 7.75% | ||||
Loan Agreement | Prime Rate | |||||
Debt Instrument [Line Items] | |||||
Debt instrument, basis spread on variable rate | 4.50% | ||||
Convertible Notes | |||||
Debt Instrument [Line Items] | |||||
Loans | $ 7,500,000 | $ 3,400,000 | |||
Debt instrument, interest rate, stated percentage | 7.00% | ||||
Debt instrument effective interest rate | 7.54% | ||||
Proceeds from convertible promissory notes | $ 10,900,000 | ||||
Convertible promissory notes subscription liability | $ 140,000 | ||||
Convertible notes, unamortized discount | 34,000 | ||||
Convertible Notes | Board of Directors | |||||
Debt Instrument [Line Items] | |||||
Loans | 250,000 | ||||
Aggregate carrying amounts of the convertible notes | 1,000,000 | ||||
Convertible Notes | Chief Executive Officer | |||||
Debt Instrument [Line Items] | |||||
Loans | $ 10,000 | ||||
Aggregate carrying amounts of the convertible notes | $ 25,000 |
Notes Payable - Schedule of Agg
Notes Payable - Schedule of Aggregate Carrying Amounts of Loans (Details) - Loan Agreement - USD ($) $ in Thousands | Dec. 31, 2017 | Dec. 31, 2016 |
Debt Instrument [Line Items] | ||
Principal | $ 10,200 | $ 17,400 |
Add: accreted liability for final payment fee | 869 | 462 |
Less: unamortized discount | (244) | (421) |
Loans, aggregate carrying amount | $ 10,825 | $ 17,441 |
Notes Payable - Schedule of Fut
Notes Payable - Schedule of Future Maturities Loans Including Final Payment Fee (Details) - USD ($) $ in Thousands | Dec. 31, 2017 | Dec. 31, 2016 |
Debt Instrument [Line Items] | ||
Notes payable, net of current portion | $ 3,625 | $ 10,241 |
Loan Agreement | ||
Debt Instrument [Line Items] | ||
Year ending December 31, 2018 | 7,200 | |
Year ending December 31, 2019 | 4,431 | |
Long-term debt at maturity | 11,631 | |
Unaccreted balance for final payment fee on Loans | (562) | |
Less: unamortized discount | (244) | (421) |
Loans, aggregate carrying amount | 10,825 | $ 17,441 |
Less current portion | (7,200) | |
Notes payable, net of current portion | $ 3,625 |
Stockholders' Equity (Deficit42
Stockholders' Equity (Deficit) - Additional Information (Details) - $ / shares | 12 Months Ended | ||
Dec. 31, 2017 | Apr. 19, 2017 | Dec. 31, 2016 | |
Class Of Stock [Line Items] | |||
Stock split description | In March 2017, the Company’s board of directors and stockholders approved a 1-for-6.9 reverse stock split of the Company’s outstanding common stock. The accompanying financial statements and notes to the financial statements give retroactive effect to the reverse stock split for all periods presented. | ||
Reverse stock split description | 1-for-6.9 | ||
Common stock, shares authorized | 200,000,000 | 77,800,000 | |
Common stock, par value | $ 0.001 | $ 0.001 | |
Preferred stock, shares authorized | 10,000,000 | ||
Preferred stock, par value | $ 0.001 | ||
Common stock, shares outstanding | 19,882,551 | 2,202,517 | |
IPO | |||
Class Of Stock [Line Items] | |||
Outstanding shares of convertible preferred stock converted into common stock, shares | 6,690,066 | ||
Common stock, shares authorized | 200,000,000 | ||
Common stock, par value | $ 0.001 | ||
Preferred stock, shares authorized | 10,000,000 | ||
Preferred stock, par value | $ 0.001 |
Stockholders' Equity (Deficit43
Stockholders' Equity (Deficit) - Schedule of Common Stock Reserved for Future Issuance (Details) - shares | Dec. 31, 2017 | Dec. 31, 2016 |
Conversion of Preferred Stock Warrants Issued and Outstanding | ||
Class Of Stock [Line Items] | ||
Common stock reserved for future issuance | 9,936 | |
Convertible Preferred Stock (as-converted) | ||
Class Of Stock [Line Items] | ||
Common stock reserved for future issuance | 6,690,070 | |
Shares Reserved for Issuance Under the ESPP | ||
Class Of Stock [Line Items] | ||
Common stock reserved for future issuance | 199,879 | |
Warrants | ||
Class Of Stock [Line Items] | ||
Common stock reserved for future issuance | 10,660 | 724 |
Stock Options | ||
Class Of Stock [Line Items] | ||
Common stock reserved for future issuance | 2,589,348 | 1,385,855 |
Shares Reserved for Future Award Grants | ||
Class Of Stock [Line Items] | ||
Common stock reserved for future issuance | 513,333 | 172,495 |
Equity Incentive Plan and Sto44
Equity Incentive Plan and Stock-Based Compensation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands | Jan. 01, 2018 | Mar. 31, 2017 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | Apr. 12, 2017 |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] | ||||||
Common stock shares issued under ESPP | 50,121 | |||||
Cash received from options exercised during the period | $ 81 | $ 10 | $ 157 | |||
2017 Employee Stock Purchase Plan | ||||||
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] | ||||||
Shares available for future grants | 199,879 | |||||
Shares price, per share | $ 8.50 | |||||
Time-Based Vesting Provisions | ||||||
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] | ||||||
Weighted average per share fair value granted | 10.39 | $ 9.69 | $ 13.56 | |||
Performance-Based Vesting Provisions | ||||||
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] | ||||||
Weighted average per share fair value granted | $ 6.73 | |||||
Stock options outstanding | 188,651 | |||||
Stock Purchase Rights | ||||||
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] | ||||||
Unrecognized compensation expense | $ 400 | |||||
Weighted-average period over which unrecognized compensation expense is expected to be recognized | 8 months 12 days | |||||
Stock Purchase Rights | 2017 Employee Stock Purchase Plan | ||||||
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] | ||||||
Shares of common stock reserved under the plan | 250,000 | |||||
Percentage of maximum earnings withhold by employee to purchase shares | 15.00% | |||||
Discounted stock price percentage on the date of offering | 85.00% | |||||
Discounted stock price percentage on the date of purchase | 85.00% | |||||
Annual increase in maximum percentage of number of shares of common stock reserved for issuance | 1.00% | |||||
Annual increase in maximum number of shares of common stock reserved for issuance | 300,000 | |||||
Weighted average per share fair value granted | $ 4.61 | |||||
Cash received from options exercised during the period | $ 400 | |||||
Stock Options | ||||||
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] | ||||||
Shares available for future grants | 2,589,348 | 1,385,855 | ||||
Unrecognized compensation expense | $ 16,300 | |||||
Weighted-average period over which unrecognized compensation expense is expected to be recognized | 3 years | |||||
Subsequent Event | 2017 Employee Stock Purchase Plan | ||||||
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] | ||||||
Shares available for future grants | 398,705 | |||||
Increased number of shares available for future grants | 198,826 | |||||
2017 Equity Incentive Plan | ||||||
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] | ||||||
Shares available for future grants | 1,600,000 | |||||
Annual increase in percentage of number of shares of common stock reserved for issuance | 4.00% | |||||
Options to purchase common stock expiration term | 10 years | |||||
2017 Equity Incentive Plan | Time-Based Vesting Provisions | ||||||
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] | ||||||
Stock options vesting period | 4 years | |||||
2017 Equity Incentive Plan | Performance-Based Vesting Provisions | ||||||
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] | ||||||
Stock options vesting description | Grants with performance-based vesting provisions vest upon the achievement of three separate development and regulatory milestones, with one-third of the options vesting upon the achievement of each milestone. | |||||
2017 Equity Incentive Plan | Vesting After First Year | Time-Based Vesting Provisions | ||||||
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] | ||||||
Stock options vesting percentage | 25.00% | |||||
2017 Equity Incentive Plan | Balance Vesting Monthly Over the Remaining Terms | Time-Based Vesting Provisions | ||||||
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] | ||||||
Stock options vesting period | 36 months | |||||
2017 Equity Incentive Plan | Subsequent Event | ||||||
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] | ||||||
Shares available for future grants | 1,308,635 | |||||
Increased number of shares available for future grants | 795,302 | |||||
2009 Equity Incentive Plan | ||||||
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] | ||||||
Shares available for future grants | 75,517 | |||||
2009 and 2017 Equity Incentive Plans | ||||||
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] | ||||||
Shares available for future grants | 513,333 | |||||
Shares of common stock reserved under the plan | 3,102,681 | |||||
Number of shares reserved for issuance upon exercise of granted and outstanding stock options | 2,589,348 | |||||
Stock options outstanding | 2,589,348 | 1,385,855 | ||||
2009 and 2017 Equity Incentive Plans | Time-Based Vesting Provisions | ||||||
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] | ||||||
Stock options outstanding | 2,400,697 | |||||
2009 and 2017 Equity Incentive Plans | Performance-Based Vesting Provisions | ||||||
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] | ||||||
Stock options outstanding | 188,651 |
Equity Incentive Plan and Sto45
Equity Incentive Plan and Stock-Based Compensation - Summary of Stock Option Activity (Details) $ / shares in Units, $ in Thousands | 12 Months Ended |
Dec. 31, 2017USD ($)$ / sharesshares | |
Performance-Based Vesting Provisions | |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] | |
Shares Subject to Options, Outstanding at December 31, 2017 | 188,651 |
2009 and 2017 Equity Incentive Plans | |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] | |
Shares Subject to Options, Outstanding at December 31, 2016 | 1,385,855 |
Shares Subject to Options, Granted | 1,400,245 |
Shares Subject to Options, Exercised | (55,669) |
Shares Subject to Options, Forfeitures and cancellations | (141,083) |
Shares Subject to Options, Outstanding at December 31, 2017 | 2,589,348 |
Weighted-Average Exercise Price per Share, Outstanding at December 31, 2016 | $ / shares | $ 11.35 |
Weighted-Average Exercise Price per Share, Granted | $ / shares | 14.92 |
Weighted-Average Exercise Price per Share, Exercised | $ / shares | 1.45 |
Weighted-Average Exercise Price per Share, Forfeitures and cancellations | $ / shares | 14.39 |
Weighted-Average Exercise Price per Share, Outstanding at December 31, 2017 | $ / shares | $ 13.33 |
Weighted-Average Remaining Contractual Term, Outstanding at December 31, 2017 | 8 years 1 month 6 days |
Aggregate Intrinsic Value, Outstanding at December 31, 2017 | $ | $ 2,643 |
2009 and 2017 Equity Incentive Plans | Time-Based Vesting Provisions | |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] | |
Shares Subject to Options, Outstanding at December 31, 2017 | 2,400,697 |
Shares Subject to Options, Vested and expected to vest | 2,400,697 |
Shares Subject to Options, Exercisable | 742,213 |
Weighted-Average Exercise Price per Share, Outstanding at December 31, 2017 | $ / shares | $ 13.09 |
Weighted-Average Exercise Price per Share, Vested and expected to vest | $ / shares | 13.09 |
Weighted-Average Exercise Price per Share, Exercisable | $ / shares | $ 8.68 |
Weighted-Average Remaining Contractual Term, Outstanding at December 31, 2017 | 8 years 1 month 6 days |
Weighted-Average Remaining Contractual Term, Vested and expected to vest | 8 years 1 month 6 days |
Weighted-Average Remaining Contractual Term, Exercisable | 5 years 7 months 6 days |
Aggregate Intrinsic Value, Outstanding at December 31, 2017 | $ | $ 2,643 |
Aggregate Intrinsic Value, Vested and expected to vest | $ | 2,643 |
Aggregate Intrinsic Value, Exercisable | $ | $ 2,602 |
2009 and 2017 Equity Incentive Plans | Performance-Based Vesting Provisions | |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] | |
Shares Subject to Options, Outstanding at December 31, 2017 | 188,651 |
Weighted-Average Exercise Price per Share, Outstanding at December 31, 2017 | $ / shares | $ 16.30 |
Weighted-Average Remaining Contractual Term, Outstanding at December 31, 2017 | 8 years 10 months 24 days |
Equity Incentive Plan and Sto46
Equity Incentive Plan and Stock-Based Compensation - Summary of Information Regarding Stock Options (Details) - USD ($) $ in Thousands | 12 Months Ended | ||
Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | |
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract] | |||
Fair value of options vested during the period | $ 2,194 | $ 1,087 | $ 862 |
Cash received from options exercised during the period | 81 | 10 | 157 |
Intrinsic value of options exercised during the period | $ 677 | $ 62 | $ 160 |
Equity Incentive Plan and Sto47
Equity Incentive Plan and Stock-Based Compensation - Summary of Fair Value of Employee Stock Option Grants with Both Time-Based and Performance-Based Vesting Provisions and Stock Purchase Rights (Details) - $ / shares | 12 Months Ended | ||
Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | |
Time-Based Vesting Provisions | |||
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] | |||
Risk-free interest rate | 1.63% | 1.61% | |
Risk-free interest rate, minimum | 1.83% | ||
Risk-free interest rate, maximum | 2.27% | ||
Expected volatility, minimum | 75.90% | 73.30% | 73.50% |
Expected volatility, maximum | 87.50% | 73.50% | 86.80% |
Weighted-average volatility | 82.20% | 73.40% | 82.20% |
Dividend yield | 0.00% | 0.00% | 0.00% |
Weighted-average expected term (in years) | 6 years 1 month 6 days | 6 years 1 month 6 days | 6 years 1 month 6 days |
Weighted-average grant date fair value per share | $ 10.39 | $ 9.69 | $ 13.56 |
Performance-Based Vesting Provisions | |||
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] | |||
Risk-free interest rate, minimum | 1.98% | ||
Risk-free interest rate, maximum | 2.17% | ||
Expected volatility, minimum | 75.20% | ||
Expected volatility, maximum | 76.30% | ||
Weighted-average volatility | 75.90% | ||
Dividend yield | 0.00% | ||
Weighted-average expected term (in years) | 6 years 3 months 19 days | ||
Weighted-average grant date fair value per share | $ 6.73 | ||
Purchase Rights | 2017 Employee Stock Purchase Plan | |||
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] | |||
Risk-free interest rate, minimum | 1.04% | ||
Risk-free interest rate, maximum | 1.82% | ||
Expected volatility, minimum | 65.70% | ||
Expected volatility, maximum | 84.40% | ||
Weighted-average volatility | 69.60% | ||
Dividend yield | 0.00% | ||
Weighted-average expected term (in years) | 1 year 3 months 18 days | ||
Weighted-average grant date fair value per share | $ 4.61 |
Equity Incentive Plan and Sto48
Equity Incentive Plan and Stock-Based Compensation - Summary of Total Non-Cash Stock-Based Compensation Expense for All Stock Awards and Purchase Rights, Net of Forfeitures Recognized (Details) - USD ($) $ in Thousands | 12 Months Ended | ||
Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | |
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] | |||
Total non-cash stock-based compensation expense | $ 4,451 | $ 1,323 | $ 1,062 |
Research and Development | |||
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] | |||
Total non-cash stock-based compensation expense | 1,783 | 562 | 456 |
General and Administrative | |||
Share Based Compensation Arrangement By Share Based Payment Award [Line Items] | |||
Total non-cash stock-based compensation expense | $ 2,668 | $ 761 | $ 606 |
License and Collaboration Agr49
License and Collaboration Agreements - Additional Information (Details) - Siemens - USD ($) $ in Millions | 1 Months Ended | |
Jun. 30, 2015 | Dec. 31, 2011 | |
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items] | ||
Reimburse percentage of future costs of new assay development. | 50.00% | |
Minimum | ||
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items] | ||
Royalty payment percentage of net assay revenue. | 10.00% | |
Maximum | ||
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items] | ||
Royalty payment percentage of net assay revenue. | 20.00% | |
Up-front Payment Arrangement | ||
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items] | ||
Initial payment received under collaboration agreement | $ 0.5 |
Grant Agreements - Additional I
Grant Agreements - Additional Information (Details) - USD ($) | 1 Months Ended | 12 Months Ended |
Aug. 31, 2017 | Dec. 31, 2017 | |
OOPD Grant | ||
Grant Agreements [Line Items] | ||
Award granted by government | $ 2,000,000 | |
Reimbursement of qualifying expenses period | 4 years | |
Proceed from reimbursable amounts relating to grant as offset against research and development costs incurred | $ 500,000 | |
Accelerate Brain Cancer Cure, Inc. (ABC2) | ||
Grant Agreements [Line Items] | ||
Potential sales that need to occur in order for grantor to obtain payment | $ 5,000,000 | |
Grant term period | 10 years | |
Amount awarded under grant agreement | $ 0 | |
Repayment liability | 0 | |
Accelerate Brain Cancer Cure, Inc. (ABC2) | Maximum | ||
Grant Agreements [Line Items] | ||
Amount awarded under grant agreement | 200,000 | |
American Brain Tumor Association (ABTA) | ||
Grant Agreements [Line Items] | ||
Potential sales that need to occur in order for grantor to obtain payment | $ 5,000,000 | |
Grant term period | 10 years | |
Amount awarded under grant agreement | $ 0 | |
Repayment liability | 0 | |
American Brain Tumor Association (ABTA) | Maximum | ||
Grant Agreements [Line Items] | ||
Amount awarded under grant agreement | 200,000 | |
Voices Against Brain Cancer (VABC) | ||
Grant Agreements [Line Items] | ||
Potential sales that need to occur in order for grantor to obtain payment | $ 5,000,000 | |
Grant term period | 5 years | |
Repayment liability | $ 0 | |
Voices Against Brain Cancer (VABC) | Maximum | ||
Grant Agreements [Line Items] | ||
Amount awarded under grant agreement | $ 300,000 |
Income Taxes - Additional Infor
Income Taxes - Additional Information (Details) - USD ($) | 12 Months Ended | |||
Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | |
Income Tax Disclosure [Line Items] | ||||
Current income tax expense (benefit) | $ 0 | $ 0 | $ 0 | |
Deferred tax expense (benefit) | 0 | 0 | $ 0 | |
Valuation allowance increased, amount | $ 400,000 | 400,000 | ||
Cumulative change in ownership percentage | 50.00% | |||
Period for cumulative change in ownership | 3 years | |||
Deferred tax assets for net operating losses | $ 31,800,000 | |||
Deferred tax assets for federal and California research and development credits | 24,200,000 | |||
Accruals interest for uncertain tax position | 0 | 0 | ||
Penalties for uncertain tax positions | $ 0 | $ 0 | ||
Federal statutory rate | 34.00% | 34.00% | 34.00% | |
Provisional amount of tax recorded due to newly enacted Tax Act | $ 1,400,000 | |||
Scenario Plan | ||||
Income Tax Disclosure [Line Items] | ||||
Federal statutory rate | 21.00% | |||
State | ||||
Income Tax Disclosure [Line Items] | ||||
Net operating loss carryforwards expiration year | 2,028 | |||
Federal | ||||
Income Tax Disclosure [Line Items] | ||||
Net operating loss carryforwards | $ 137,800,000 | |||
Net operating loss carryforwards expiration year | 2,028 | |||
Federal | Research and Development | ||||
Income Tax Disclosure [Line Items] | ||||
Tax credit carryforward | $ 20,500,000 | |||
Tax credit carryforward expiration year | 2,028 | |||
California | ||||
Income Tax Disclosure [Line Items] | ||||
Net operating loss carryforwards | $ 41,500,000 | |||
Percentage of apportionment of losses | 100.00% | |||
Cumulative net operating loss carryforwards | $ 109,600,000 | |||
California | Research and Development | ||||
Income Tax Disclosure [Line Items] | ||||
Tax credit carryforward | $ 4,700,000 |
Income Taxes - Reconciliation o
Income Taxes - Reconciliation of U.S. Statutory Federal Income Tax Rate (Details) | 12 Months Ended | ||
Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | |
Income Tax Disclosure [Abstract] | |||
Federal statutory rate | 34.00% | 34.00% | 34.00% |
Adjustments for tax effects of: | |||
State taxes, net | 5.70% | 5.60% | 5.60% |
Permanent adjustments | (4.50%) | (5.40%) | (4.80%) |
Tax Cuts and Jobs Act | (3.70%) | ||
Net operating loss carryovers not recognized | (30.40%) | (32.80%) | (33.30%) |
Valuation allowance | (1.00%) | (1.10%) | (1.70%) |
Other | (0.10%) | (0.30%) | 0.20% |
Income Taxes - Components of De
Income Taxes - Components of Deferred Taxes (Details) - USD ($) $ in Thousands | Dec. 31, 2017 | Dec. 31, 2016 |
Deferred tax assets: | ||
Depreciation and amortization | $ 52 | $ 52 |
Deferred license revenue | 15 | 38 |
Share-based compensation | 1,459 | 1,062 |
Accrued liabilities and other | 808 | 796 |
Total deferred tax assets | 2,334 | 1,948 |
Less valuation allowance | $ (2,334) | $ (1,948) |
Retirement Plan - Additional In
Retirement Plan - Additional Information (Details) - USD ($) | 12 Months Ended | ||
Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | |
Compensation And Retirement Disclosure [Abstract] | |||
Defined benefit plan, contributions by employer | $ 0 | $ 0 | $ 0 |
Commitments and Contingencies -
Commitments and Contingencies - Additional Information (Details) | Mar. 09, 2018USD ($) | Jan. 10, 2018USD ($)ft²LeaseOption | Dec. 31, 2017USD ($) | Dec. 31, 2016USD ($) | Dec. 31, 2015USD ($) | Dec. 31, 2018ft² |
Subsequent Event | ||||||
Commitments And Contingencies [Line Items] | ||||||
Future minimum obligations under operating lease commitments due during 2018 | $ 384,000 | |||||
Laboratory And Office Space | ||||||
Commitments And Contingencies [Line Items] | ||||||
Rent expense | $ 400,000 | $ 400,000 | $ 300,000 | |||
Future minimum obligations under operating lease commitments due during 2018 | $ 71,000 | |||||
Laboratory And Office Space | Amended Lease | Scenario, Forecast | ||||||
Commitments And Contingencies [Line Items] | ||||||
Area of laboratory and office space under operating lease | ft² | 2,000 | |||||
Laboratory And Office Space | Subsequent Event | CALIFORNIA | ||||||
Commitments And Contingencies [Line Items] | ||||||
Area of laboratory and office space under operating lease | ft² | 39,000 | |||||
Lease possible commencement date | Jun. 1, 2018 | |||||
Initial lease term | 8 years | |||||
Number of options to extend lease | LeaseOption | 1 | |||||
Additional lease term | 5 years | |||||
Abatement of tenant improvement allowance | $ 1,200,000 | |||||
Laboratory And Office Space | Subsequent Event | Amended Lease | ||||||
Commitments And Contingencies [Line Items] | ||||||
Expiration date of extended lease term | Jun. 30, 2018 | |||||
Future minimum obligations related to extension of the existing lease during 2018 | $ 200,000 |
Commitments and Contingencies56
Commitments and Contingencies - Schedule of Future Annual Minimum Rental Payments Payable Under New Lease (Details) - Subsequent Event $ in Thousands | Jan. 10, 2018USD ($) |
Commitments And Contingencies [Line Items] | |
2,018 | $ 384 |
2,019 | 1,802 |
2,020 | 1,945 |
2,021 | 2,013 |
2,022 | 2,083 |
Thereafter | 7,674 |
Total | $ 15,901 |
Selected Quarterly Financial 57
Selected Quarterly Financial Data (unaudited) - Unaudited Quarterly Financial Information (Details) - USD ($) $ / shares in Units, $ in Thousands | 3 Months Ended | 12 Months Ended | |||||||||
Dec. 31, 2017 | Sep. 30, 2017 | Jun. 30, 2017 | Mar. 31, 2017 | Dec. 31, 2016 | Sep. 30, 2016 | Jun. 30, 2016 | Mar. 31, 2016 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | |
Quarterly Financial Information Disclosure [Abstract] | |||||||||||
Operating expenses | $ 10,697 | $ 9,747 | $ 8,662 | $ 8,564 | $ 7,985 | $ 8,542 | $ 7,633 | $ 7,580 | $ 37,670 | $ 31,740 | $ 23,005 |
Net Loss | $ (10,837) | $ (9,953) | $ (9,066) | $ (9,073) | $ (8,430) | $ (9,000) | $ (8,042) | $ (8,006) | $ (38,929) | $ (33,478) | $ (23,056) |
Net loss per common share, basic and diluted | $ (0.55) | $ (0.50) | $ (0.56) | $ (4.11) | $ (3.83) | $ (4.09) | $ (3.66) | $ (3.64) | $ (2.66) | $ (15.22) | $ (10.57) |