Pulse Biosciences (PLSE) 10-K 16 Mar 18 2017 FY Annual report Financial data

Document And Entity Information

Document And Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2017	Feb. 28, 2018	Jun. 30, 2017
Document And Entity Information [Abstract]
Entity Registrant Name	Pulse Biosciences, Inc.
Entity Filer Category	Accelerated Filer
Entity Central Index Key	1,625,101
Trading Symbol	plse
Amendment Flag	false
Document Type	10-K
Document Fiscal Period Focus	FY
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2,017
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Common Stock, Shares Outstanding		16,841,172
Entity Public Float			$ 201,795,000

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 3,386	$ 2,089
Investments	34,683	14,306
Prepaid expenses and other current assets	412	268
Total current assets	38,481	16,663
Property and equipment, net	2,570	317
Intangible assets, net	5,878	6,543
Goodwill	2,791	2,791
Other asset	101
Total assets	49,821	26,314
Current liabilities:
Accounts payable	782	265
Accrued expenses	1,034	751
Deferred rent, current	397
Total current liabilities	2,213	1,016
Deferred rent	1,613
Total liabilities	3,826	1,016
Commitments and contingencies (Note 12)
Stockholders' equity:
Preferred stock, $0.001 par value; authorized - 5,000 shares; issued and outstanding - none
Common stock, $0.001 par value: authorized – 45,000 shares; issued and outstanding – 16,819 shares and 13,315 shares at December 31, 2017 and December 31, 2016, respectively	17	13
Additional paid-in-capital	84,202	37,898
Accumulated other comprehensive loss	(51)	(7)
Accumulated deficit	(38,173)	(12,606)
Total stockholders' equity	45,995	25,298
Total liabilities and stockholders' equity	$ 49,821	$ 26,314

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2017	Dec. 31, 2016
Consolidated Balance Sheets [Abstract]
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	45,000,000	45,000,000
Common stock, shares issued	16,819,000	13,315,000
Common stock, shares outstanding	16,819,000	13,315,000

Consolidated Statements Of Oper

Consolidated Statements Of Operations And Comprehensive Loss - USD ($) shares in Thousands, $ 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
Consolidated Statements Of Operations And Comprehensive Loss [Abstract]
Revenue
Operating expenses:
General and administrative	$ 5,801	$ 4,434	$ 3,924	$ 1,344	$ 1,027	$ 1,079	$ 665	$ 644	15,503	3,415	1,621
Research and development	2,864	2,925	2,130	1,727	1,649	1,553	1,430	874	9,646	5,506	2,181
Amortization of intangible assets	166	166	167	166	167	166	166	166	665	665	666
Total operating expenses	8,831	7,525	6,221	3,237	2,843	2,798	2,261	1,684	25,814	9,586	4,468
Other income:
Interest income	128	39	41	39	34	31	3		247	68
Total other income	128	39	41	39	34	31	3		247	68
Loss from operations, before income taxes	(8,703)	(7,486)	(6,180)	(3,198)	(2,809)	(2,767)	(2,258)	(1,684)	(25,567)	(9,518)	(4,468)
Income tax benefit											(1,657)
Net loss	(8,703)	(7,486)	(6,180)	(3,198)	(2,809)	(2,767)	(2,258)	(1,684)	(25,567)	(9,518)	(2,811)
Other comprehensive loss:
Unrealized loss on available-for-sale securities, net of tax	(49)	4	3	(2)	1	(8)			(44)	(7)
Comprehensive loss	$ (8,752)	$ (7,482)	$ (6,177)	$ (3,200)	$ (2,808)	$ (2,775)	$ (2,258)	$ (1,684)	$ (25,611)	$ (9,525)	$ (2,811)
Net loss per share:
Basic and diluted net loss per share	$ (0.53)	$ (0.52)	$ (0.43)	$ (0.23)	$ (0.21)	$ (0.21)	$ (0.23)	$ (0.22)	$ (1.73)	$ (0.86)	$ (0.37)
Weighted average shares used to compute net loss per common share - basic and diluted	16,574	14,381	14,233	13,803	13,315	13,315	9,791	7,565	14,754	11,009	7,565

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Common Stock [Member]Private Placement [Member]	Common Stock [Member]Common Stock Warrants [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]Private Placement [Member]	Additional Paid-in Capital [Member]Common Stock Warrants [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Loss [Member]Private Placement [Member]	Accumulated Other Comprehensive Loss [Member]	Accumulated Deficit [Member]Private Placement [Member]	Accumulated Deficit [Member]	Private Placement [Member]	Common Stock Warrants [Member]	Total
Balance at Dec. 31, 2014			$ 8			$ 16,343				$ (277)			$ 16,074
Balance, shares at Dec. 31, 2014			7,565,000
Stock-based compensation expense						402							402
Net loss										(2,811)			(2,811)
Balance at Dec. 31, 2015			$ 8			16,745				(3,088)			13,665
Balance, shares at Dec. 31, 2015			7,565,000
Shares issued upon closing			$ 5			20,283							20,288
Shares issued upon closing, shares			5,750,000
Stock-based compensation expense						870							870
Unrealized loss on available-for-sale securities, net of tax								(7)					(7)
Net loss										(9,518)			(9,518)
Balance at Dec. 31, 2016			$ 13			37,898		(7)		(12,606)			$ 25,298
Balance, shares at Dec. 31, 2016			13,315,000										13,315,000
Shares issued upon closing	$ 3			$ 34,840							$ 34,843
Shares issued upon closing, shares	2,820,000
Shares issued upon exercise of stock options			$ 1		$ 50	488						$ 50	$ 489
Shares issued upon exercise of stock options, shares		522,000	162,000									624,901	162,991
Stock-based compensation expense						10,926							$ 10,926
Unrealized loss on available-for-sale securities, net of tax								(44)					(44)
Net loss										(25,567)			(25,567)
Balance at Dec. 31, 2017			$ 17			$ 84,202		$ (51)		$ (38,173)			$ 45,995
Balance, shares at Dec. 31, 2017			16,819,000										16,819,000

Consolidated Statements of Sto6

Consolidated Statements of Stockholders' Equity (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Initial Public Offering [Member]
Issuance costs		$ 2,711
Private Placement [Member]
Issuance costs	$ 199

Consolidated Statements Of Cash

Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities:
Net loss	$ (25,567)	$ (9,518)	$ (2,811)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	336	94	51
Amortization of intangible assets	665	665	666
Stock-based compensation	10,926	870	402
Net premium amortization on available-for-sale securities	26	4
Landlord incentive for tenant improvements	2,119
Change in deferred income taxes			(1,657)
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(144)	(135)	(12)
Deferred offering costs		(280)	(347)
Accounts payable	517	3	125
Accrued expenses	245	246	305
Other asset	(101)
Deferred rent	(109)
Deferred grant revenue			(39)
Net Cash Provided by (Used in) Operating Activities, Total	(11,087)	(8,051)	(3,317)
Cash flows from investing activities:
Purchases of property and equipment	(2,551)	(64)	(86)
Purchase of available-for-sale securities	(43,595)	(19,067)
Maturities of available-for-sale securities	23,148	4,750
Net cash used in investing activities	(22,998)	(14,381)	(86)
Cash flows from financing activities:
Proceeds from exercises of stock options and warrants	539
Proceeds from issuance of common stock from private offering, net of issuance costs	34,843
Proceeds from issuance of common stock from initial public offering, net of issuance costs		20,915
Net cash provided by financing activities	35,382	20,915
Net increase (decrease) in cash	1,297	(1,517)	(3,403)
Cash and cash equivalents at beginning of period	2,089	3,606	7,009
Cash and cash equivalents at end of period	3,386	2,089	3,606
Supplemental disclosure of noncash investing and financing activities:
Reclassification of deferred offering costs to additional paid-in capital upon initial public offering		627
Equipment purchased in accrued expenses	$ 38	$ 18	$ 104

Description Of The Business

Description Of The Business	12 Months Ended
	Dec. 31, 2017
Description Of The Business [Abstract]
Description Of The Business	1. Description of the Business Pulse Biosciences, Inc., incorporated in Nevada on May 19, 2014 , is a medical technology company developing commercial clinical applications for its proprietary Nano-Pulse Stimulation (“NPS”) technology. NPS is a novel patented technology that leverages nano-second duration energy pulses that have demonstrated effective local tumor control and the initiation of an adaptive immune response in pre-clinical studies. The Company is pursuing a number of potential clinical applications for NPS, including oncology and dermatology where the Company believes NPS may provide greater benefits compared to current therapies and treatments. The Company’s headquarters and research facility are located in Hayward, California. The Company’s activities are subject to significant risks and uncertainties, including the need for additional capital. The Company has not yet commenced any revenue-generating operations, does not have any cash flows from operations, and will need to raise additional capital to finance its operations. However, there can be no assurances that the Company will be able to obtain additional financing on acceptable terms and in the amounts necessary to fully fund its operating requirements.

Summary Of Significant Accounti

Summary Of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2017
Summary Of Significant Accounting Policies [Abstract]
Summary Of Significant Accounting Policies	2. Summary of Significant Accounting Policies Principles of Consolidation The accompanying consolidated financial statements are prepared in accordance with accounting principles generally accepted in the United States (“U.S. GAAP”) and include the financial statements of the Company and its wholly-owned subsidiaries. Intercompany balances and transactions have been eliminated in consolidation. Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires the Company to make estimates and assumptions that affect the amounts reported in the Financial Statements and accompanying notes to the Financial Statements. Estimates include, but are not limited to, the valuation of cash equivalents and investments, clinical trial accruals, the valuation and recognition of share-based compensation and useful lives assigned to long-lived assets. Actual amounts could differ from these estimates . Concentration of Credit Risk Financial instruments that potentially subject the Company to a concentration of credit risk consist of cash and cash equivalents and investments. The Company places its cash equivalents and investments with high credit quality financial institutions and, by policy, limits the amounts invested with any one financial institution or issuer. Deposits held with banks may exceed the amount of insurance provided on such deposits. The Company has not experienced any losses since inception. Fair Value of Financial Instruments The Company believes the carrying amounts of its financial instruments, including cash equivalents, prepaid expenses and other current assets, accounts payable and accrued expenses, approximate fair value due to the short-term nature of such instruments.  Cash, Cash Equivalents and Investments The Company considers all highly liquid investments purchased with an original maturity of three months or less to be cash equivalents. The Company has designated all investments as available-for-sale and therefore, such investments are reported at fair value, with unrealized gains and losses recognized in accumulated other comprehensive income (loss) (“OCI”) in stockholders’ equity. The cost of marketable securities is adjusted for the amortization of premiums and discounts to expected maturity. Premium and discount amortization is included in other income, net. Realized gains and losses, as well as interest income, on available-for-sale securities are also included in other income, net. The Company includes all of its available-for-sale securities in current assets. All of the Company’s investments are subject to a periodic impairment review. The Company recognizes an impairment loss when a decline in the fair value of its marketable investments below the cost basis is judged to be other-than-temporary. Factors considered in determining whether a loss is temporary include the length of time and extent to which the marketable investments fair value has been less than the cost basis, the financial condition and near-term prospects of the investee, extent of the loss related to credit of the issuer, the expected cash flows from the security, the Company’s intent to sell the security and whether or not the Company will be required to sell the security before the recovery of its amortized cost. No impairment losses were incurred during the periods presented . Property and Equipment Leasehold improvements are amortized using the straight-line method over the shorter of the lease term or estimated useful life. Equipment is recorded at cost and depreciated using the straight-line method over their estimated useful lives, ranging from three to five years. Intangible Assets The Company’s intangible assets consist of acquired patents and licenses, which are being amortized over their estimated useful lives of twelve years. Long-Lived Assets The Company reviews long-lived assets, consisting of property and equipment and intangible assets, for impairment during each fiscal year or when events or changes in circumstances indicate the carrying value of these assets may exceed their current fair values. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to the estimated undiscounted future cash flows expected to be generated by the asset. N o impairment losses were incurred during the periods presented. Goodwill The Company records goodwill when the consideration paid in a business acquisition exceeds the fair value of the net tangible assets and the identified intangible assets acquired. The Company reviews goodwill for impairment at least annually or whenever changes in circumstances indicate that the carrying value of the goodwill may not be recoverable. As of December 31, 2017, there has been no impairment of goodwill. Stock-Based Compensation The Company recognizes the cost of stock-based compensation in the financial statements based upon fair value. The fair value of stock options is determined as of the grant date using the Black-Scholes option pricing model. The fair value of restricted stock and restricted stock unit (RSU) awards is determined based on the number of units granted and the closing price of the Company’s common stock on the grant date. The fair value of each purchase under the employee stock purchase plan (ESPP) is estimated at the beginning of the offering period using the Black-Scholes option pricing model. The Company’s determination of the fair value of equity-settled awards is impacted by the price of the Company's common stock as well as changes in assumptions regarding a number of complex and subjective variables. These variables include, but are not limited to, the expected term that awards will remain outstanding, expected common stock price volatility over the term of the awards, risk-free interest rates and expected dividends. The fair value of an award is recognized over the period during which service is required to be performed in exchange for the award, the requisite service period (usually the vesting period) on a straight-line basis. Equity instruments issued to non-employees are recorded at their fair value on the measurement date and are subject to periodic adjustments as the underlying equity instruments vest. The fair value of these equity instruments are expensed over the service period. Estimates of the fair value of equity-settled awards as of the grant date using valuation models, such as the Black-Scholes option pricing model, are affected by assumptions regarding a number of complex variables. Changes in the assumptions can materially affect the fair value of the award and ultimately how much stock-based compensation expense is recognized. These inputs are subjective and generally require significant analysis and judgment to develop. The Company determines the volatility factor based on the historical volatilities of comparable public companies in similar industries. The risk-free interest rate is based on the yield available on U.S. Treasury zero-coupon issues similar in duration to the expected term of the equity-settled award. For all stock options granted to date, the Company used the Staff Accounting Bulletin, No. 110 (SAB 110) simplified method to calculate the expected term, which is the average of the contractual term and vesting period. Prior to the Company’s IPO, the fair value of common stock was determined by reference to either recent or anticipated cash transactions involving the sale of the Company’s common stock. The Company recognizes the fair value of stock-based compensation costs in general and administrative costs and in research and development costs, as appropriate, in the Company’s consolidated statements of operations. Research and Development Costs Research and development costs consist primarily of compensation costs, fees paid to consultants and outside service providers and organizations (including research institutes at universities), development prototypes and other expenses relating to the acquisition, design, development and testing of the Company’s product candidates. Research and development costs incurred by the Company are expensed as incurred, unless the achievement of milestones, the completion of contracted work, or other information indicates that a different expensing schedule is more appropriate. Patent Costs The Company is the owner of numerous domestic and foreign patents. Due to the significant uncertainty associated with the successful development of one or more commercially viable products based on the Company’s research efforts and any related patent applications, patent costs not related to acquired patents, including patent-related legal fees, filing fees and other costs, including internally generated costs, are expensed as incurred. During the years ended December 31, 2017, 2016 and 2015, patent costs totaled $0.8 million, $0.5 million and $0.4 million, respectively . Patent costs are included in general and administrative costs in the consolidated statements of operations and comprehensive loss. Income Taxes The Company accounts for income taxes under an asset and liability approach for financial accounting and reporting for income taxes. Accordingly, the Company recognizes deferred tax assets and liabilities for the expected impact of differences between the financial statements and the tax basis of assets and liabilities. The Company records a valuation allowance to reduce its deferred tax assets to the amount that is more likely than not to be realized. In the event the Company determines that it would be able to realize its deferred tax assets in the future in excess of its recorded amount, an adjustment to the deferred tax assets would be credited to operations in the period such determination was made. Likewise, should the Company determine that it would not be able to realize all or part of its deferred tax assets in the future, an adjustment to the deferred tax assets would be charged to operations in the period such determination was made. The Company is subject to U.S. federal income taxes and income taxes in California. As the Company’s net operating losses have yet to be utilized, previous tax years remain open to examination by federal authorities and other jurisdictions in which the Company currently operates or has operated in the past. The Company is not currently under examination by any tax authority. The Company accounts for uncertainties in income tax law under a comprehensive model for the financial statement recognition, measurement, presentation and disclosure of uncertain tax positions taken or expected to be taken in income tax returns as prescribed by U.S. GAAP. The tax effects of a position are recognized only if it is “more-likely-than-not” to be sustained by the taxing authority as of the reporting date. If the tax position is not considered “more-likely-than-not” to be sustained, then no benefits of the position are recognized. At December 31, 2017 and 2016, the Company had not recorded any liability for uncertain tax positions. The Company includes interest and penalties related to uncertain tax positions as a component of income tax expense. Comprehensive Loss Comprehensive loss consists of net loss and unrealized gains or losses on available-for-sale investments. The Company displays comprehensive loss and its components as part of the consolidated statements of operations and comprehensive loss. Net Loss per Share The Company’s basic net loss per share is calculated by dividing the net loss by the weighted average number of shares of common stock outstanding for the period. Diluted net loss per share is computed by giving effect to all potential dilutive common stock equivalents outstanding for the period. For purposes of this calculation, options to purchase common stock and common stock warrants are considered common stock equivalents. Potential common shares that have an anti-dilutive effect (i.e., those that increase income per share or decrease loss per share) are excluded from the calculation of diluted net loss per share. Basic and diluted net loss per common share is the same for all periods presented because all warrants and stock options outstanding are anti-dilutive. The following outstanding stock options, warrants and restricted stock units to purchase common stock were excluded from the computation of diluted net loss per share for the periods presented because including them would have had an anti-dilutive effect:       Year Ended December 31,  2017 2016 2015  Common stock warrants 249,709 874,610 299,625  Common stock options 2,598,659 1,229,355 875,221  Restricted stock units 229,774 — —  Total 3,078,142 2,103,965 1,174,846 Segment and Geographical Information The Company operates and manages its business as one reportable and operating segment. The Company’s Chief Executive Officer, who is the chief operating decision maker, reviews financial information on an aggregate basis for purposes of allocating resources and evaluating financial performance. All of the Company’s assets are based in the United States.  Reclassification Certain items in the prior period financial statements have been reclassified to conform to the presentation in the current period financial statements. During the years ended December 31, 2016 and 2015, patent legal costs of  $0.5 million and $0.4 million, respectively, were reclassified from research and development expenses to general and administrative expenses. These changes did not impact loss from operations or net loss. Recent Accounting Pronouncements Recently Adopted Accounting Standards During March 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2016-09, Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-based Payment Accounting . This ASU simplifies the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. This ASU requires that excess tax benefits and deficiencies be recognized as income tax benefit or expense in the income statement. The Company adopted this ASU as of January 1, 2017. The adoption of this ASU did not have a significant impact on the Company’s financial statements. During January 2017, the FASB issued ASU 2017-04, Intangibles — Goodwill and Other (Topic 350): Simplifying the Accounting for Goodwill Impairment , which simplifies the accounting for goodwill impairment. This ASU removes Step 2 of the goodwill impairment test, which requires hypothetical purchase price allocation. A goodwill impairment will now be the amount by which a reporting unit’s carrying value exceeds its fair value, not to exceed the carrying amount of goodwill. The new guidance also requires disclosure of the amount of goodwill at reporting units with zero or negative carrying amounts. ASU 2017-04 is effective for the Company beginning January 1, 2020. The Company elected to early adopt this standard when performing its annual goodwill impairment test in 2017. The adoption of this ASU did not have a significant financial impact on the Company’s financial statements. During May 2017, the FASB issued ASU 2017-09, Compensation — Stock Compensation (Topic 718) : Scope of Modification Accounting. This standard provides clarification on when modification accounting should be used for changes to the terms or conditions of a share-based payment award. This standard does not change the accounting for modifications but clarifies that modification accounting guidance should only be applied if there is a change to the value, vesting conditions, or award classification and would not be required if the changes are considered non-substantive. The amendments in this ASU are effective for the Company effective beginning January 1, 2018, with early adoption permitted. This ASU should be applied prospectively on and after the effective date. The Company adopted this ASU during 2017. The adoption of this ASU did not have a significant financial impact on the Company’s financial statements. Recently Issued Accounting Standards During May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers , requiring an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers . This updated standard will replace most existing revenue recognition guidance in U.S. GAAP when it becomes effective and permits the use of either the retrospective or cumulative effect transition method. In August 2015, the FASB issued an update to defer the effective date of this update to periods beginning after December 15, 2017 . This updated standard becomes effective for the Company in the first quarter of fiscal year 2018 . The Company expects to adopt this standard upon commencing revenue generating activities. Since the Company has not recognized or generated revenue to date, it does not expect the adoption of this pronouncement on January 1, 2018 to have any impact to its financial statements. During February 2016, the FASB issued ASU No. 2016-02, Leases , which amends the existing accounting standards for leases. The new standard requires lessees to record a right-of-use asset and a corresponding lease liability on the balance sheet (with the exception of short-term leases). For lessees, leases will continue to be classified as either operating or financing in the income statement. This ASU becomes effective for the Company in the first quarter of fiscal year 2019 and early adoption is permitted. This ASU is required to be applied with a modified retrospective approach and requires application of the new standard at the beginning of the earliest comparative period presented. The Company generally does not finance purchases of equipment or other capital, but does lease its facilities. While the Company is continuing to assess all potential impacts of this standard, it expects that most of its lease commitments will be subject to the updated standard and recognized as lease liabilities and right-of-use assets upon adoption.

Investments And Fair Value Of F

Investments And Fair Value Of Financial Instruments	12 Months Ended
	Dec. 31, 2017
Investments And Fair Value Of Financial Instruments [Abstract]
Investments And Fair Value Of Financial Instruments	3. Investments and Fair Value of Financial Instruments Investments The Company’s investments have been classified and accounted for as available-for-sale. The Company’s investments consisted of the following (in thousands):      December 31, 2017  Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value  Commercial paper $ 7,216 $ — $ (6) $ 7,210  Corporate bonds 19,524 — (33) 19,491  Asset-backed securities 7,994 — (12) 7,982  Total assets measured at fair value $ 34,734 $ — $ (51) $ 34,683      December 31, 2016  Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value  Corporate bonds $ 13,295 $ 1 $ (7) $ 13,289  Asset-backed securities 1,017 — — 1,017  Total assets measured at fair value $ 14,312 $ 1 $ (7) $ 14,306 The contractual maturities of the Company’s investments were as follows (in thousands):      December 31,  Investments 2017 2016  Due in one year $ 30,096 $ 14,306  Due in one to two years 4,587 —  Total $ 34,683 $ 14,306 Fair Value of Financial Instruments The Company determines the fair value of its financial instruments based on a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value into three levels: Level 1 - Observable inputs such as quoted prices in active markets for an identical asset or liability that the Company has the ability to access as of the measurement date. Financial assets and liabilities utilizing Level 1 inputs include money market funds. Level 2 - Inputs, other than quoted prices included within Level 1, which are directly observable for the asset or liability or indirectly observable through corroboration with observable market data. Financial assets and liabilities utilizing Level 2 inputs include commercial paper, corporate bonds and asset-backed securities. Level 3 - Unobservable inputs in which there is little or no market data for the asset or liability which requires the reporting entity to develop its own assumptions. The Company did not classify any of its investments within Level 3 of the fair value hierarchy. The following table sets forth the fair value of the Company’s financial assets measured on a recurring basis (in thousands):      December 31, 2017  Assets Classification Level 1 Level 2 Level 3 Total  Money market funds Cash and cash equivalents $ 2,758 $ — $ — $ 2,758  Commercial paper Investments — 7,210 7,210  Corporate bonds Investments — 19,491 — 19,491  Asset-backed securities Investments — 7,982 — 7,982  Total assets measured at fair value $ 2,758 $ 34,683 $ — $ 37,441       December 31, 2016  Assets Classification Level 1 Level 2 Level 3 Total  Money market funds Cash and cash equivalents $ 1,726 $ — $ — $ 1,726  Corporate bonds Investments — 13,289 — 13,289  Asset-backed security Investments — 1,017 — 1,017  Total assets measured at fair value $ 1,726 $ 14,306 $ — $ 16,032  During year ended December 31, 2017 and 2016, the Company did not record impairment charges related to its marketable investments. During the year ended December 31, 2017 and 2016, the Company did not have any transfers between Level 1, Level 2 or Level 3 of the fair value hierarchy. Additionally, the Company did not have any financial assets and liabilities measured at fair value on a non-recurring basis as of December 31, 2017 or December 31, 2016.

Property And Equipment, Net

Property And Equipment, Net	12 Months Ended
	Dec. 31, 2017
Property And Equipment, Net [Abstract]
Property And Equipment, Net	4. Property and Equipment, Net Property and equipment, net consisted of the following (in thousands):      December 31,  2017 2016  Leasehold improvements $ 2,257 $ —  Laboratory equipment 484 425  Furniture, fixtures and equipment 231 17  Software 79 20  3,051 462  Less: Accumulated depreciation and amortization (481) (145)  $ 2,570 $ 317  During June 2017, the Company prepared to move into new office space in Hayward, California, and its landlord provided $2.1 million for leasehold improvements pursuant to the tenant allowance clause in the lease agreement between the Company and its landlord which has been capitalized and amortized over the shorter of the lease term or estimated useful life.  Depreciation and amortization expense for the years ended December 31, 2017, 2016 and 2015 was $336,000, $94,000 and $51,000 , respectively.

Intangible Assets, Net

Intangible Assets, Net	12 Months Ended
	Dec. 31, 2017
Intangible Assets, Net [Abstract]
Intangible Assets, Net	5 . Intangible Assets, Net Intangible assets primarily consist of a license to utilize certain patents, know-how and technology relating to NPS for biomedical applications acquired from Old Dominion University Research Foundation, Eastern Virginia Medical School, and the University of Southern California. In addition, the Company entered into a Sponsored Research Agreement with Old Dominion University’s Frank Reidy Research Center for Bioelectrics, a leading research organization in the field, which includes certain intellectual property rights arising from the research. Intangible assets, net consisted of the following (in thousands):       December 31,  2017 2016  Acquired patents and licenses $ 7,985 $ 7,985  Less: Accumulated amortization (2,107) (1,442)  $ 5,878 $ 6,543  A schedule of the amortization of intangible assets for the five years ending December 31, 2018 through 2022 and thereafter is as follows (in thousands):       Year Ending December 31:  2018 $ 665  2019 666  2020 665  2021 666  2022 665  Thereafter 2,551  $ 5,878 

Goodwill

Goodwill	12 Months Ended
	Dec. 31, 2017
Goodwill [Abstract]
Goodwill	6. Goodwill  In 2014, the Company acquired three companies (the “acquisitions”) for aggregate consideration of $5.5 million. In accordance with ASC Topic 805, Business Combinations , the Company recorded goodwill of $2.8 million in connection with the acquisitions as the consideration paid exceeded the fair value of the net tangible assets and the intangible assets acquired.   The Company reviews goodwill for impairment at least annually or whenever changes in circumstances indicate that the carrying amount of goodwill may not be recoverable. Based on the Company’s annual impairment test as of December 31, 2017, 2016 and 2015, the Company determined that no impairment of goodwill existed, and was not aware of any indicators of impairment at such date.

Accrued Expenses

Accrued Expenses	12 Months Ended
	Dec. 31, 2017
Accrued Expenses [Abstract]
Accrued Expenses	7. Accrued Expenses Accrued expenses consisted of the following (in thousands):      December 31,  2017 2016  Compensation expense $ 685 $ 261  Professional fees 211 285  Other 73 205  Supplies 65 —  $ 1,034 $ 751 

Stockholders' Equity And Stock-

Stockholders' Equity And Stock-Based Compensation	12 Months Ended
	Dec. 31, 2017
Stockholders' Equity And Stock-Based Compensation [Abstract]
Stockholders' Equity And Stock-Based Compensation	8. Stockholders’ Equity and Stock-Based Compensation Preferred Stock The Company has authorized a total of 5,000,000 shares of preferred stock, par value $0.001 per share, none of which were outstanding at December 31, 2017 and 2016. The Company’s Board of Directors has the authority to issue preferred stock and to determine the rights, preferences, privileges, and restrictions, including voting rights, without any further vote or action by the Company’s stockholders. Common Stock The Company has authorized a total of 45,000,000 shares of common stock, par value $0.001 per share. Initial Public Offering During May 2016 through June 2016, the Company closed its initial public offering (“IPO”), whereby the Company sold 5,749,846 shares of common stock at $4.00 per share. The Company received net proceeds of approximately $20.3 million from the IPO, including proceeds from the exercise of the overallotment option granted to the underwriters, net of underwriting discounts and commissions and other offering costs. Private Placements On February 7, 2017, the Company entered into a securities purchase agreement with Robert W. Duggan and Maky Zanganeh (the “Investors”), pursuant to which the Company, in a private placement, issued and sold to the Investors an aggregate of 819,673 shares of the Company’s common stock, par value $0.001 per share, at a price per share of $6.10 , for net proceeds of approximately $4,965,000 . On September 24, 2017, the Company entered into a securities purchase agreement with Robert W. Duggan, pursuant to which the Company, in a private placement, issued and sold to Robert W. Duggan an aggregate of 2,000,000 shares of the Company’s common stock, par value $0.001 per share, at a price per share of $15.02 , for net proceeds of approximately $29,878,000 . In connection with this private placement, the Company granted certain registration rights to Robert W. Duggan, pursuant to which, among other things, the Company intends to prepare and file with the Securities and Exchange Commission a registration statement to register for resale of these shares during 2018. Common Stock Warrants During the year ended December 31, 2016, in connection with the closing of the Company’s initial public offering, the Company issued warrants as compensation to the underwriters of its initial public offering to purchase a total 574,985 shares of its common stock at a price of $5.00 per share. These warrants are exercisable for a period of five years. These warrants were valued pursuant to the Black-Scholes option-pricing model based on the following assumptions: fair value of common stock – $4.12 to $4.27 per share; risk free interest rate: 1.22% – 1.38% ; expected volatility – 80% ; expected dividend yield – 0% ; and expected term – 5 years. A summary of warrant activity for the year ended December 31, 2017 is presented below:      Weighted  Average  Weighted Remaining  Number of Average Contractual  Shares Exercise Price Life (in Years)  Warrants outstanding at December 31, 2016 874,610 $ 4.20 4.53  Issued — —  Exercised (624,901) 4.23  Expired/terminated — —  Warrants outstanding and exercisable at December 31, 2017 249,709 $ 4.14 3.56   During the year ended December 31, 2017, warrants to purchase 624,901 shares of common stock were either cash or net exercised, resulting in the issuance of approximately 522,451 shares of common stock.  The intrinsic value of exercisable in-the-money stock warrants was approximately $4.9 million as of December 31, 2017 . Equity Plans 2017 Equity Incentive Plan and 2017 Inducement Equity Incentive Plan The Board of Directors (the “Board”) of the Company previously adopted, and the Company’s stockholders approved, the Company’s 2017 Equity Incentive Plan (the “2017 Plan”). The 2017 Plan has a 10 -year term, and provides for the grant of stock options, stock appreciation rights, restricted stock, restricted stock units, performance units, and performance shares to employees, directors and consultants of the Company and any parent or subsidiary of the Company, as the Compensation Committee of the Board of Directors may determine. Subject to an annual evergreen increase and adjustment in the case of certain capitalization events, 1,500,000 shares of the Company’s common stock are authorized for issuance pursuant to awards under the 2017 Plan. In addition, shares remaining available under the Company’s 2015 Equity Incentive Plan, as amended (the “2015 Plan”), and shares reserved but not issued pursuant to outstanding equity awards that expire or terminate without being exercised or that are forfeited or repurchased by the Company will be added to the shares of common stock available for issuance under the 2017 Plan. The 2017 Plan is administered by the Board’s Compensation Committee.  As of December 31, 2017 , there were no shares of common stock available for issuance under the 2017 Plan. In January 2018, the Company’s Board voted to increase the number of shares of common stock available under the 2017 Plan by 672,915 shares. In November 2017, the Board of the Company adopted the 2017 Inducement Equity Incentive Plan (the “Inducement Plan”) and reserved 1,000,000 shares of the Company’s common stock for issuance pursuant to equity awards granted under the Inducement Plan. The Inducement Plan was adopted without stockholder approval. The Inducement Plan has a 10 -year term, and provides for the grant of equity-based awards, including nonstatutory stock options, restricted stock units, restricted stock, stock appreciation rights, performance shares and performance units, and its terms are substantially similar to the Company’s 2017 Equity Incentive Plan, including with respect to treatment of equity awards in the event of a “merger” or “change in control” as defined under the Inducement Plan. Options issued under the Inducement Plan may have a term up to ten years and have variable vesting provisions. New hire grants generally vest 25% upon the first anniversary of the grant and 1/12 quarterly thereafter, over the subsequent twelve quarters. Equity-based awards issued under the Inducement Plan are only issuable to individuals not previously engaged as employees or non-employee directors of the Company prior to the Inducement Plan’s adoption date. As of December 31, 2017, 907,000 shares of common stock were available for issuance under the Inducement Plan. 2017 Employee Stock Purchase Plan The Board of the Company previously adopted, subject to stockholder approval, the Company’s 2017 Employee Stock Purchase Plan (the “2017 ESPP”). At the Annual Meeting, the stockholders approved the 2017 ESPP. The 2017 ESPP is a broad-based plan that provides employees of the Company and its designated affiliates with the opportunity to become stockholders through periodic payroll deductions that are applied towards the purchase of Company common shares at a discount from the then-current market price. Subject to adjustment in the case of certain capitalization events, a total of 250,000 common shares of the Company are available for purchase under the 2017 ESPP. As of December 31, 2017, no shares had been issued from the 2017 ESPP, and 250,000 shares of common stock was reserved for issuance. In January 2018, the Company’s Board voted to increase the number of shares of common stock available under the 2017 ESPP by 252,343 shares. A summary of stock option activity under the 2015 Plan, 2017 Plan and Inducement Plan for the year ended December 31, 2017 is presented below:      Weighted  Weighted Average  Average Remaining  Number of Exercise Contractual  Shares Price Life (in Years)  Stock options outstanding at December 31, 2016 1,229,355 $ 3.82 7.6  Issued 1,552,986 25.67  Exercised (162,991) 3.12  Expired/terminated (20,691) 9.14  Stock options outstanding at December 31, 2017 2,598,659 $ 16.88  Vested and expected to vest at December 31, 2017 2,598,659 $ 16.88 8.2  Stock options exercisable at December 31, 2017 831,687 $ 10.99 6.3 The exercise prices of stock options outstanding and exercisable are as follows at December 31, 2017:      Options Outstanding Options Exercisable  Weighted average  Number remaining contractual Weighted average Number Weighted average  Exercise Price outstanding life (in years) exercise price vested exercise price  $2.67 - $4.28 835,773 6.4 $ 3.72 514,280 $ 3.53  $4.67 - $7.55 261,400 8.7 5.17 75,074 5.15  $12.25 - $19.99 118,000 9.6 19.14 4,603 12.25  $21.55 - $30.99 1,383,486 9.2 26.85 237,730 28.94  2,598,659 8.2 $ 16.88 831,687 $ 10.99    The intrinsic value of stock options exercised during the year ended December 31, 2017, 2016 and 2015 was $3.8 million, $0 and $0 , respectively. The intrinsic value of exercisable in-the-money stock options at December 31, 2017 was approximately $11.8 million . The fair value of employee stock options was estimated using the Black-Scholes option-pricing model utilizing the following assumptions:        Year Ended December 31,  2017 2016 2015  Expected term in years 0.42 - 6.08 6.08 3.5 - 6.25  Expected volatility 70% - 90% 80% 89% - 90%  Risk-free interest rate 1.00% - 2.20% 1.16% - 1.45% 0.88% - 1.89%  Dividend yield — — —  The fair value of the stock options granted to employees and directors during the years ended December 31, 2017, 2016 and 2015, calculated pursuant to the Black-Scholes option-pricing model, was $26.8 million, $1.2 million and $3.1 million, respectively . The fair value of ESPP was estimated using the Black-Scholes option-pricing model utilizing the following assumptions:     Year Ended December 31,  2017  Expected term in years 0.5 - 1.3  Expected volatility 95%  Risk-free interest rate 1.1% - 1.2%  Dividend yield —  Total stock-based compensation expense consisted of the following (in thousands):         Year Ended December 31,  2017 2016 2015  General and administrative $ 9,136 $ 674 $ 397  Research and development 1,790 196 5  Total stock-based compensation expense $ 10,926 $ 870 $ 402  The fair value of restricted stock unit (“RSUs”) awards is determined based on the number of units granted and the closing price of the Company’s common stock as of the grant date. The estimated fair value of RSUs is recognized on a straight-line basis over the requisite service period. During 2017, the Company granted 160,974 RSUs to an officer, with a cliff vest in June 2018 . The stock-based compensation expense related to these RSUs was approximately $2.9 million during 2017. As of December 31, 2017, there was $2.1 million of unrecognized compensation expense related to these RSUs.  During the year ended December 31, 2017, the Company granted 68,800 RSUs to certain employees which vest 50% on June 1, 2019 with the remaining 50% vesting on June 1, 2021 . In the event of a change in control, these RSUs vest 100% . The stock-based compensation expense recorded in 2017 related to these RSUs was approximately $0.1 million. As of December 31, 2017, there was $1.2 million of unrecognized compensation expense related to these RSUs.  In November 2017, the Board of Directors of the Company accepted resignations of certain members of its board of directors resulting in the full vesting of their outstanding equity awards. This resulted in the Company recording an additional $1.2 million of stock-based compensation expense for the year ended December 31, 2017. At December 31, 2017, there was $22.1 m illion of unrecognized compensation cost related to unvested stock-based compensation arrangements, which is expected to be recognized over a weighted average period of 3.0 years.

Research Grants And Agreements

Research Grants And Agreements	12 Months Ended
	Dec. 31, 2017
Research Grants And Agreements [Abstract]
Research Grants And Agreements	9. Research Grants and Agreements Sponsored Research Agreement The Company entered into a Sponsored Research Agreement (“SRA”) with Old Dominion University Research Foundation (“ODURF”) during 2014 pursuant to which the Company sponsors research activities performed by ODURF’s Frank Reidy Center. ODURF is compensated by the Company for its conduct of each study in accordance with the budget and payment terms set forth in the applicable task order. During the years ended December 31, 2017 and 2016, the Company agreed to sponsor $740,000 and $1.0 million, respectively, in research during the subsequent 12 -month period to be funded through monthly payments made upon ODURF certifying, to the Company’s reasonable satisfaction, that ODURF has met its obligations pursuant to the specified task order and statement of work. The principal investigator may transfer funds with the budget as needed without the Company’s approval so long as the obligations of ODURF under the task order and statement of work remain unchanged and unimpaired. As of December 31, 2017, there was $370,000 of approved budget remaining under this research agreement. In addition, during the year ended December 31, 2017, the Company agreed to provide $300,000 in research funding to researchers affiliated with ODURF and Eastern Virginia Medical School matching funds made available to those researchers by the Virginia Biosciences Health Research Corporation. The Company’s sponsorship affords access to certain intellectual property, if any, developed during the project. As of December 31, 2017, there was approximately $150,000 remaining available under this sponsorship. During the years ended December 31, 2017, 2016 and 2015, the Company incurred costs relating to the SRA equal to $0.8 million, $0.9 million and $1.0 million, respectively.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2017
Income Taxes [Abstract]
Income Taxes	10. Income Taxes The income tax provision for the years ended December 31, 2017 and 2016 was $0 and $0 , respectively. The income tax provision for the year ended December 31, 2015 was a benefit of $1.7 million. The tax benefits for the year ended December 31, 2015 resulted from the realization of deferred tax assets related principally to the Company’s net operating loss for the year ended December 31, 2015, offset by deferred tax liability created based upon the difference in the value for book and tax purposes of certain acquired technology assets, which are considered temporary income tax differences under purchase accounting. A full valuation allowance is provided against the Company’s remaining deferred tax assets. Deferred income taxes reflect the net tax effects of temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. Significant components of the Company’s deferred tax assets at December 31, 2017 and 2016 are summarized below (in thousands):        December 31,  2017 2016  Technology $ (863) $ (1,449)  Temporary differences 36 40  Credits 1,536 639  Stock compensation 3,067 272  Net operating loss carryforwards 7,715 5,121  Total deferred tax assets 11,491 4,623  Valuation allowance (11,491) (4,623)  Net deferred tax assets $ — $ —  In assessing the potential realization of deferred tax assets, management considers whether it is more likely than not that some portion or all of the deferred tax assets will be realized. The ultimate realization of deferred tax assets is dependent upon the Company attaining future taxable income during the periods in which those temporary differences become deductible. At December 31, 2017 and 2016, management was unable to determine that it was more likely than not that the Company’s deferred tax assets will be realized, and has therefore recorded an appropriate valuation allowance against deferred tax assets at such dates. The Company’s effective tax rate is different from the federal statutory tax rate of 35% due primarily to net losses that receive no tax benefit as a result of a valuation allowance recorded for such losses. Presented below is the reconcilement of the difference between the tax rate computed by applying the U.S. federal statutory tax rate and the effective tax rate for the years ended December 31, 2017, 2016 and 2015:       Year Ended December 31,  2017 2016 2015  U.S. federal statutory tax rate (35.0) % (35.0) % (35.0) %  Valuation allowance 23.0 42.0 4.0  Tax reform 18.0 — —  Permanent differences 1.0 2.0 1.0  State tax benefit and other (7.0) (9.0) (7.0)  Effective tax rate — % — % (37.0) %  At December 31, 2017, the Company had federal and California state net operating loss carryforwards of approximately $25.8 million and $25.9 million, respectively. The federal and state net operating loss carryforwards will begin to expire after 2032 . At December 31, 2017, the Company had approximately $1.2 million and $ 0.9 million of federal and California R&D credits, respectively. The federal R&D credits begin to expire after 2035 and the California R&D credits have an indefinite carryforward period. These net operating loss carryforward and research and development credit amounts have full valuation allowances against them due to the remoteness of their expected utilization. The Company’s activity related to unrecognized tax benefits are summarized below (in thousands):     December 31,  2017 2016  Balance at the beginning of the year $ 213 $ 66  Gross increases - tax positions in prior periods 37 —  Gross decreases - tax positions in prior periods — —  Gross increases - tax position in current period 262 147  Settlements — —  Lapses in statutes of limitations — —  Balance at the end of the year $ 512 $ 213    Although it is reasonably possible that certain unrecognized tax benefits may increase or decrease within the next twelve months due to tax examination changes, settlement activities, expirations of statute of limitations, or the impact on recognition and measurement considerations related to the results of published tax cases or other similar activities, the Company does not anticipate any significant changes to unrecognized tax benefits over the next twelve months. During the years ended December 31, 2017, 2016 and 2015, no interest or penalties were required to be recognized related to unrecognized tax benefits. Although the Company is not under examination, the tax years for 2014 and forward are subject to examination by United States tax authorities.  On December 22, 2017, the Tax Cuts and Jobs Act (the “Tax Act”) was signed into law. The Tax Act contains significant changes to corporate taxation, including (i) the reduction of the corporate income tax rate to 21% , (ii) the acceleration of expensing for certain business assets, (iii) the one-time transition tax related to the transition of U.S. international tax from a worldwide tax system to a territorial tax system, (iv) the repeal of the domestic production deduction, (v) additional limitations on the deductibility of interest expense and (vi) expanded limitations on executive compensation.  The key impact of the Tax Act on our financial statement for the year ended December 31, 2017, was the re-measurement of deferred tax balances to the new corporate tax rate. In order to calculate the effects of the new corporate tax rate on our deferred tax balances, ASC 740 “Income Taxes” (“ASC 740”) required the re-measurement of our deferred tax balances as of the enactment date of the Tax Act, based on the rates at which the balances are expected to reverse in the future. The re-measurement of our deferred tax balances resulted in a net reduction in deferred tax assets of $4.7 million offset with a corresponding adjustment to the valuation allowance. The Company performed a formal analysis of the availability of these operating loss carryforwards at December 31, 2017 under Internal Revenue Code Sections 382 and 383, and management expects that the Company’s ability to use its net operating loss carryforwards may be limited in future periods. 

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2017
Related Party Transactions [Abstract]
Related Party Transactions	11. Related Party Transactions On November 2, 2017, the Company appointed Ken Clark to the Board of Directors. Mr. Clark is a member of the law firm of Wilson Sonsini Goodrich and Rosati (“WSGR”), which is also outside corporate counsel to the Company. During the year ended December 31, 2017, the Company incurred expenses for legal services rendered by WSGR totaling approximately $0.7 million. During September 2017, the Company entered into a securities purchase agreement with Robert W. Duggan, a significant stockholder of the Company and Chairman of the Board effective November 2, 2017, pursuant to which the Company issued and sold to Robert W. Duggan an aggregate of 2,000,000 shares of the Company’s common stock, par value $0.001 per share, at a price per share of $15.02 . At the time of the transaction, Mr. Duggan owned approximately 27% of the Company’s then outstanding securities, and approximately 35% of the Company’s outstanding common stock as of December 31, 2017. MDB Capital Group, LLC (“MDB”) provided investment banking, executive recruiting and intellectual property management services to the Company. The Company’s former Chairman of the Board, Robert Levande, was a Senior Managing Director of MDB throughout his tenure on the Company’s Board. During the year ended December 31, 2016, the Company incurred $100,000 for services rendered by MDB with respect to intellectual property management. The Company did not incur any amounts for intellectual property management services by MDB during the year ended December 31, 2017. Similarly, during the year ended December 31, 2015, the Company incurred expenses charged by MDB comprised of: $49,000 for services rendered with respect to executive search activities related to the hiring of the Company’s Chief Executive Officer and the appointment of one director, $42,000 for offering related expenses and $26,000 for intellectual property related services. In connection with the Company’s 2016 IPO (Note 8), the underwriting syndicate led by MDB received $1.8 million in underwriting discounts, $0.2 million in unaccountable expense reimbursements and warrants valued in the aggregate of $1.4 million. Gary Schuman, the Chief Financial Officer of MDB, was also the acting Chief Financial Officer of the Company and was compensated at a monthly rate of $4,000 from November 1, 2014 to December 31, 2015, reflecting an aggregate charge to general and administrative expenses of $48,000 for the year ended December 31, 2015.

Commitments And Contingencies

Commitments And Contingencies	12 Months Ended
	Dec. 31, 2017
Commitments And Contingencies [Abstract]
Commitments And Contingencies	12. Commitments and Contingencies Operating Leases The Company leased approximately 4,300 square feet of corporate offices and research facilities in Burlingame, California, at a monthly cost of approximately $21,000 . This lease expired on June 30, 2017 . In January 2017, the Company entered into a new lease agreement (The “Lease”) for premises consisting of approximately 15,700 rentable square feet located in Hayward, California (the “Premises”). The Company took possession of the Premises in late June 2017 and moved into the Premises in July 2017. The Premises is being used for the Company’s corporate headquarters and principal operating facility. The term of the Lease is sixty-two ( 62 ) months, which commenced on July 1, 2017. Base rent was abated for the first two (2) months of the Lease term and thereafter is $42,400 per month during the first year of the Lease term, with specified annual increases thereafter until reaching approximately $50,300 per month during the last two (2) months of the Lease term. The Company paid a refundable security deposit of approximately $101,000 . The landlord provided the Company with improvement allowances in the amount of approximately $135.00 per rentable square foot of the Premises, which was applied towards the costs of construction of the initial improvements in the Premises . We also agreed to reimburse the landlord in the event that certain expenses are incurred by the landlord during the Lease term . We have the right to extend the Lease term by five (5) years upon written notice not more than twelve (12) months nor less than nine (9) months prior to the expiration of the original Lease term, with monthly payments equal to the “Fair Rental Value” as defined in the Lease. During the year ended December 31, 2017, the landlord incurred approximately $2.1 million related to the initial tenant leasehold improvements and the Company capitalized these leasehold improvements to property and equipment and a corresponding deferred rent liability on its balance sheet. During the years ended December 31, 2017, 2016 and 2015, rent expense, including common area maintenance charges, was $0.3 million, $0.2 million and $0.2 million, respectively. Future minimum lease payments under the non-cancelable operating leases as of December 31, 2017 are as follows (in thousands):     Year Ending December 31:  2018 $ 518  2019 536  2020 554  2021 574  2022 392  Thereafter —  $ 2,574 Litigation The Company and certain directors have received subpoenas from the Securities and Exchange Commission requesting documents and other information in connection with an investigation into trading in the Company’s stock in advance of the Company’s September 2017 announcement of the stock purchase agreement executed between the Company and Robert Duggan. The Company is cooperating with the investigation. The Company maintains indemnification agreements with its directors and officers that may require the Company to indemnify them against liabilities that arise by reason of their status or service as directors or officers, except as prohibited by applicable law. At this time, the Company is unable to estimate a possible loss, if any, associated with the matter described above . From time to time, the Company may be involved in a variety of claims, lawsuits, investigations and proceedings relating to securities laws, product liability, patent infringement, contract disputes and other matters relating to various claims that arise in the normal course of our business in addition to governmental and other regulatory investigations and proceedings. In addition, third parties may, from time to time, assert claims against the Company in the form of letters and other communications. The Company currently believes that these ordinary course matters will not have a material adverse effect on our business; however, the results of litigation and claims are inherently unpredictable. Regardless of the outcome, litigation can have an adverse impact on the Company because of defense and settlement costs, diversion of management resources and other factors. 

Employee Benefit Plans

Employee Benefit Plans	12 Months Ended
	Dec. 31, 2017
Employee Benefit Plans [Abstract]
Employee Benefit Plans	13. Employee Benefit Plans The Company sponsors a defined contribution plan under which it may make discretionary contributions. The Company did not make any employer matching contributions to this plan during the years ended December 31, 2017, 2016 and 2015.

Selected Quarterly Financial Da

Selected Quarterly Financial Data	12 Months Ended
	Dec. 31, 2017
Selected Quarterly Financial Data [Abstract]
Selected Quarterly Financial Data	 14. Selected Quarterly Financial Data (Unaudited)  During the quarters ended March 31, June 30 and September 30, 2017, patent legal costs of $124,000 , $152,000 and $275,000 , respectively, were reclassified from research and development costs to general and administrative costs. During the quarters ended March 31, June 30, September 30 and December 31, 2016, patent legal costs of $116,000 , $23,000 , $186,000 and $157,000 , respectively, were reclassified from research and development costs to general and administrative costs. These changes did not impact loss from operations or net loss. The selected financial data below has been adjusted for such reclassifications.  The following table provides the selected quarterly financial data for the years ended December 31, 2017 and 2016 (in thousands, except per share data):     Quarter Ended  2017 2016  December 31, September 30, June 30, March 31, December 31, September 30, June 30, March 31,  Revenue $ — $ — $ — $ — $ — $ — $ — $ —  Operating expenses:  General and administrative 5,801 4,434 3,924 1,344 1,027 1,079 665 644  Research and development 2,864 2,925 2,130 1,727 1,649 1,553 1,430 874  Amortization of intangible assets 166 166 167 166 167 166 166 166  Total operating expenses 8,831 7,525 6,221 3,237 2,843 2,798 2,261 1,684  Other income:  Interest income 128 39 41 39 34 31 3 —  Total other income 128 39 41 39 34 31 3 —  Loss from operations, before income taxes (8,703) (7,486) (6,180) (3,198) (2,809) (2,767) (2,258) (1,684)  Income tax benefit — — — — — — — —  Net loss (8,703) (7,486) (6,180) (3,198) (2,809) (2,767) (2,258) (1,684)  Other comprehensive loss:  Unrealized gain (loss) on available-for-sale securities, net of tax: (49) 4 3 (2) 1 (8) — —  Comprehensive loss $ (8,752) $ (7,482) $ (6,177) $ (3,200) $ (2,808) $ (2,775) $ (2,258) $ (1,684)  Net loss per share  Basic and diluted net loss per share $ (0.53) $ (0.52) $ (0.43) $ (0.23) $ (0.21) $ (0.21) $ (0.23) $ (0.22)  Weighted average shares used to compute net loss per common share — basic and diluted 16,574 14,381 14,233 13,803 13,315 13,315 9,791 7,565  

Summary Of Significant Accoun22

Summary Of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2017
Summary Of Significant Accounting Policies [Abstract]
Principles of Consolidation	Principles of Consolidation The accompanying consolidated financial statements are prepared in accordance with accounting principles generally accepted in the United States (“U.S. GAAP”) and include the financial statements of the Company and its wholly-owned subsidiaries. Intercompany balances and transactions have been eliminated in consolidation.
Use Of Estimates	Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires the Company to make estimates and assumptions that affect the amounts reported in the Financial Statements and accompanying notes to the Financial Statements. Estimates include, but are not limited to, the valuation of cash equivalents and investments, clinical trial accruals, the valuation and recognition of share-based compensation and useful lives assigned to long-lived assets. Actual amounts could differ from these estimates .
Concentration Of Credit Risk	Concentration of Credit Risk Financial instruments that potentially subject the Company to a concentration of credit risk consist of cash and cash equivalents and investments. The Company places its cash equivalents and investments with high credit quality financial institutions and, by policy, limits the amounts invested with any one financial institution or issuer. Deposits held with banks may exceed the amount of insurance provided on such deposits. The Company has not experienced any losses since inception.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The Company believes the carrying amounts of its financial instruments, including cash equivalents, prepaid expenses and other current assets, accounts payable and accrued expenses, approximate fair value due to the short-term nature of such instruments.
Cash, Cash Equivalents, And Investments	Cash, Cash Equivalents and Investments The Company considers all highly liquid investments purchased with an original maturity of three months or less to be cash equivalents. The Company has designated all investments as available-for-sale and therefore, such investments are reported at fair value, with unrealized gains and losses recognized in accumulated other comprehensive income (loss) (“OCI”) in stockholders’ equity. The cost of marketable securities is adjusted for the amortization of premiums and discounts to expected maturity. Premium and discount amortization is included in other income, net. Realized gains and losses, as well as interest income, on available-for-sale securities are also included in other income, net. The Company includes all of its available-for-sale securities in current assets. All of the Company’s investments are subject to a periodic impairment review. The Company recognizes an impairment loss when a decline in the fair value of its marketable investments below the cost basis is judged to be other-than-temporary. Factors considered in determining whether a loss is temporary include the length of time and extent to which the marketable investments fair value has been less than the cost basis, the financial condition and near-term prospects of the investee, extent of the loss related to credit of the issuer, the expected cash flows from the security, the Company’s intent to sell the security and whether or not the Company will be required to sell the security before the recovery of its amortized cost. No impairment losses were incurred during the periods presented .
Property and Equipment	Property and Equipment Leasehold improvements are amortized using the straight-line method over the shorter of the lease term or estimated useful life. Equipment is recorded at cost and depreciated using the straight-line method over their estimated useful lives, ranging from three to five years.
Intangible Assets	Intangible Assets The Company’s intangible assets consist of acquired patents and licenses, which are being amortized over their estimated useful lives of twelve years.
Long-Lived Assets	Long-Lived Assets The Company reviews long-lived assets, consisting of property and equipment and intangible assets, for impairment during each fiscal year or when events or changes in circumstances indicate the carrying value of these assets may exceed their current fair values. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to the estimated undiscounted future cash flows expected to be generated by the asset. N o impairment losses were incurred during the periods presented.
Goodwill	Goodwill The Company records goodwill when the consideration paid in a business acquisition exceeds the fair value of the net tangible assets and the identified intangible assets acquired. The Company reviews goodwill for impairment at least annually or whenever changes in circumstances indicate that the carrying value of the goodwill may not be recoverable. As of December 31, 2017, there has been no impairment of goodwill.
Stock-Based Compensation	Stock-Based Compensation The Company recognizes the cost of stock-based compensation in the financial statements based upon fair value. The fair value of stock options is determined as of the grant date using the Black-Scholes option pricing model. The fair value of restricted stock and restricted stock unit (RSU) awards is determined based on the number of units granted and the closing price of the Company’s common stock on the grant date. The fair value of each purchase under the employee stock purchase plan (ESPP) is estimated at the beginning of the offering period using the Black-Scholes option pricing model. The Company’s determination of the fair value of equity-settled awards is impacted by the price of the Company's common stock as well as changes in assumptions regarding a number of complex and subjective variables. These variables include, but are not limited to, the expected term that awards will remain outstanding, expected common stock price volatility over the term of the awards, risk-free interest rates and expected dividends. The fair value of an award is recognized over the period during which service is required to be performed in exchange for the award, the requisite service period (usually the vesting period) on a straight-line basis. Equity instruments issued to non-employees are recorded at their fair value on the measurement date and are subject to periodic adjustments as the underlying equity instruments vest. The fair value of these equity instruments are expensed over the service period. Estimates of the fair value of equity-settled awards as of the grant date using valuation models, such as the Black-Scholes option pricing model, are affected by assumptions regarding a number of complex variables. Changes in the assumptions can materially affect the fair value of the award and ultimately how much stock-based compensation expense is recognized. These inputs are subjective and generally require significant analysis and judgment to develop. The Company determines the volatility factor based on the historical volatilities of comparable public companies in similar industries. The risk-free interest rate is based on the yield available on U.S. Treasury zero-coupon issues similar in duration to the expected term of the equity-settled award. For all stock options granted to date, the Company used the Staff Accounting Bulletin, No. 110 (SAB 110) simplified method to calculate the expected term, which is the average of the contractual term and vesting period. Prior to the Company’s IPO, the fair value of common stock was determined by reference to either recent or anticipated cash transactions involving the sale of the Company’s common stock. The Company recognizes the fair value of stock-based compensation costs in general and administrative costs and in research and development costs, as appropriate, in the Company’s consolidated statements of operations.
Research And Development Costs	Research and Development Costs Research and development costs consist primarily of compensation costs, fees paid to consultants and outside service providers and organizations (including research institutes at universities), development prototypes and other expenses relating to the acquisition, design, development and testing of the Company’s product candidates. Research and development costs incurred by the Company are expensed as incurred, unless the achievement of milestones, the completion of contracted work, or other information indicates that a different expensing schedule is more appropriate.
Patent Costs	Patent Costs The Company is the owner of numerous domestic and foreign patents. Due to the significant uncertainty associated with the successful development of one or more commercially viable products based on the Company’s research efforts and any related patent applications, patent costs not related to acquired patents, including patent-related legal fees, filing fees and other costs, including internally generated costs, are expensed as incurred. During the years ended December 31, 2017, 2016 and 2015, patent costs totaled $0.8 million, $0.5 million and $0.4 million, respectively . Patent costs are included in general and administrative costs in the consolidated statements of operations and comprehensive loss.
Income Taxes	Income Taxes The Company accounts for income taxes under an asset and liability approach for financial accounting and reporting for income taxes. Accordingly, the Company recognizes deferred tax assets and liabilities for the expected impact of differences between the financial statements and the tax basis of assets and liabilities. The Company records a valuation allowance to reduce its deferred tax assets to the amount that is more likely than not to be realized. In the event the Company determines that it would be able to realize its deferred tax assets in the future in excess of its recorded amount, an adjustment to the deferred tax assets would be credited to operations in the period such determination was made. Likewise, should the Company determine that it would not be able to realize all or part of its deferred tax assets in the future, an adjustment to the deferred tax assets would be charged to operations in the period such determination was made. The Company is subject to U.S. federal income taxes and income taxes in California. As the Company’s net operating losses have yet to be utilized, previous tax years remain open to examination by federal authorities and other jurisdictions in which the Company currently operates or has operated in the past. The Company is not currently under examination by any tax authority. The Company accounts for uncertainties in income tax law under a comprehensive model for the financial statement recognition, measurement, presentation and disclosure of uncertain tax positions taken or expected to be taken in income tax returns as prescribed by U.S. GAAP. The tax effects of a position are recognized only if it is “more-likely-than-not” to be sustained by the taxing authority as of the reporting date. If the tax position is not considered “more-likely-than-not” to be sustained, then no benefits of the position are recognized. At December 31, 2017 and 2016, the Company had not recorded any liability for uncertain tax positions. The Company includes interest and penalties related to uncertain tax positions as a component of income tax expense.
Comprehensive Loss	Comprehensive Loss Comprehensive loss consists of net loss and unrealized gains or losses on available-for-sale investments. The Company displays comprehensive loss and its components as part of the consolidated statements of operations and comprehensive loss.
Net Loss Per Share	Net Loss per Share The Company’s basic net loss per share is calculated by dividing the net loss by the weighted average number of shares of common stock outstanding for the period. Diluted net loss per share is computed by giving effect to all potential dilutive common stock equivalents outstanding for the period. For purposes of this calculation, options to purchase common stock and common stock warrants are considered common stock equivalents. Potential common shares that have an anti-dilutive effect (i.e., those that increase income per share or decrease loss per share) are excluded from the calculation of diluted net loss per share. Basic and diluted net loss per common share is the same for all periods presented because all warrants and stock options outstanding are anti-dilutive. The following outstanding stock options, warrants and restricted stock units to purchase common stock were excluded from the computation of diluted net loss per share for the periods presented because including them would have had an anti-dilutive effect:       Year Ended December 31,  2017 2016 2015  Common stock warrants 249,709 874,610 299,625  Common stock options 2,598,659 1,229,355 875,221  Restricted stock units 229,774 — —  Total 3,078,142 2,103,965 1,174,846 
Segment And Geographical Information	Segment and Geographical Information The Company operates and manages its business as one reportable and operating segment. The Company’s Chief Executive Officer, who is the chief operating decision maker, reviews financial information on an aggregate basis for purposes of allocating resources and evaluating financial performance. All of the Company’s assets are based in the United States.
Reclassification	Reclassification Certain items in the prior period financial statements have been reclassified to conform to the presentation in the current period financial statements.
Recently Adopted Standards	Recently Adopted Accounting Standards During March 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2016-09, Compensation - Stock Compensation (Topic 718): Improvements to Employee Share-based Payment Accounting . This ASU simplifies the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities, and classification on the statement of cash flows. This ASU requires that excess tax benefits and deficiencies be recognized as income tax benefit or expense in the income statement. The Company adopted this ASU as of January 1, 2017. The adoption of this ASU did not have a significant impact on the Company’s financial statements. During January 2017, the FASB issued ASU 2017-04, Intangibles — Goodwill and Other (Topic 350): Simplifying the Accounting for Goodwill Impairment , which simplifies the accounting for goodwill impairment. This ASU removes Step 2 of the goodwill impairment test, which requires hypothetical purchase price allocation. A goodwill impairment will now be the amount by which a reporting unit’s carrying value exceeds its fair value, not to exceed the carrying amount of goodwill. The new guidance also requires disclosure of the amount of goodwill at reporting units with zero or negative carrying amounts. ASU 2017-04 is effective for the Company beginning January 1, 2020. The Company elected to early adopt this standard when performing its annual goodwill impairment test in 2017. The adoption of this ASU did not have a significant financial impact on the Company’s financial statements. During May 2017, the FASB issued ASU 2017-09, Compensation — Stock Compensation (Topic 718) : Scope of Modification Accounting. This standard provides clarification on when modification accounting should be used for changes to the terms or conditions of a share-based payment award. This standard does not change the accounting for modifications but clarifies that modification accounting guidance should only be applied if there is a change to the value, vesting conditions, or award classification and would not be required if the changes are considered non-substantive. The amendments in this ASU are effective for the Company effective beginning January 1, 2018, with early adoption permitted. This ASU should be applied prospectively on and after the effective date. The Company adopted this ASU during 2017. The adoption of this ASU did not have a significant financial impact on the Company’s financial statements.
Recent Accounting Standards	Recently Issued Accounting Standards During May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers , requiring an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers . This updated standard will replace most existing revenue recognition guidance in U.S. GAAP when it becomes effective and permits the use of either the retrospective or cumulative effect transition method. In August 2015, the FASB issued an update to defer the effective date of this update to periods beginning after December 15, 2017 . This updated standard becomes effective for the Company in the first quarter of fiscal year 2018 . The Company expects to adopt this standard upon commencing revenue generating activities. Since the Company has not recognized or generated revenue to date, it does not expect the adoption of this pronouncement on January 1, 2018 to have any impact to its financial statements. During February 2016, the FASB issued ASU No. 2016-02, Leases , which amends the existing accounting standards for leases. The new standard requires lessees to record a right-of-use asset and a corresponding lease liability on the balance sheet (with the exception of short-term leases). For lessees, leases will continue to be classified as either operating or financing in the income statement. This ASU becomes effective for the Company in the first quarter of fiscal year 2019 and early adoption is permitted. This ASU is required to be applied with a modified retrospective approach and requires application of the new standard at the beginning of the earliest comparative period presented. The Company generally does not finance purchases of equipment or other capital, but does lease its facilities. While the Company is continuing to assess all potential impacts of this standard, it expects that most of its lease commitments will be subject to the updated standard and recognized as lease liabilities and right-of-use assets upon adoption.

Summary Of Significant Accoun23

Summary Of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2017
Summary Of Significant Accounting Policies [Abstract]
Anti-Dilutive Shares Excluded From Computation Of Diluted Net Loss Per Share	   Year Ended December 31,  2017 2016 2015  Common stock warrants 249,709 874,610 299,625  Common stock options 2,598,659 1,229,355 875,221  Restricted stock units 229,774 — —  Total 3,078,142 2,103,965 1,174,846 

Investments And Fair Value Of24

Investments And Fair Value Of Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2017
Investments And Fair Value Of Financial Instruments [Abstract]
Schedule Of Available-For-Sale Securities	    December 31, 2017  Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value  Commercial paper $ 7,216 $ — $ (6) $ 7,210  Corporate bonds 19,524 — (33) 19,491  Asset-backed securities 7,994 — (12) 7,982  Total assets measured at fair value $ 34,734 $ — $ (51) $ 34,683      December 31, 2016  Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value  Corporate bonds $ 13,295 $ 1 $ (7) $ 13,289  Asset-backed securities 1,017 — — 1,017  Total assets measured at fair value $ 14,312 $ 1 $ (7) $ 14,306 
Schedule Of Contractual Maturities	   December 31,  Investments 2017 2016  Due in one year $ 30,096 $ 14,306  Due in one to two years 4,587 —  Total $ 34,683 $ 14,306 
Fair Value Of Financial Assets Measured On A Recurring Basis	    December 31, 2017  Assets Classification Level 1 Level 2 Level 3 Total  Money market funds Cash and cash equivalents $ 2,758 $ — $ — $ 2,758  Commercial paper Investments — 7,210 7,210  Corporate bonds Investments — 19,491 — 19,491  Asset-backed securities Investments — 7,982 — 7,982  Total assets measured at fair value $ 2,758 $ 34,683 $ — $ 37,441       December 31, 2016  Assets Classification Level 1 Level 2 Level 3 Total  Money market funds Cash and cash equivalents $ 1,726 $ — $ — $ 1,726  Corporate bonds Investments — 13,289 — 13,289  Asset-backed security Investments — 1,017 — 1,017  Total assets measured at fair value $ 1,726 $ 14,306 $ — $ 16,032 

Property And Equipment, Net (Ta

Property And Equipment, Net (Tables)	12 Months Ended
	Dec. 31, 2017
Property And Equipment, Net [Abstract]
Schedule Of Property And Equipment, Net	   December 31,  2017 2016  Leasehold improvements $ 2,257 $ —  Laboratory equipment 484 425  Furniture, fixtures and equipment 231 17  Software 79 20  3,051 462  Less: Accumulated depreciation and amortization (481) (145)  $ 2,570 $ 317 

Intangible Assets, Net (Tables)

Intangible Assets, Net (Tables)	12 Months Ended
	Dec. 31, 2017
Intangible Assets, Net [Abstract]
Schedule Of Intangible Assets, Net	   December 31,  2017 2016  Acquired patents and licenses $ 7,985 $ 7,985  Less: Accumulated amortization (2,107) (1,442)  $ 5,878 $ 6,543 
Schedule Of Amortization Of Intangible Assets	   Year Ending December 31:  2018 $ 665  2019 666  2020 665  2021 666  2022 665  Thereafter 2,551  $ 5,878 

Accrued Expenses (Tables)

Accrued Expenses (Tables)	12 Months Ended
	Dec. 31, 2017
Accrued Expenses [Abstract]
Schedule Of Accrued Expenses	   December 31,  2017 2016  Compensation expense $ 685 $ 261  Professional fees 211 285  Other 73 205  Supplies 65 —  $ 1,034 $ 751 

Stockholders' Equity And Stoc28

Stockholders' Equity And Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2017
Summary Of Stock Warrant Activity	   Weighted  Average  Weighted Remaining  Number of Average Contractual  Shares Exercise Price Life (in Years)  Warrants outstanding at December 31, 2016 874,610 $ 4.20 4.53  Issued — —  Exercised (624,901) 4.23  Expired/terminated — —  Warrants outstanding and exercisable at December 31, 2017 249,709 $ 4.14 3.56 
Summary Of Stock Option Activity	   Weighted  Weighted Average  Average Remaining  Number of Exercise Contractual  Shares Price Life (in Years)  Stock options outstanding at December 31, 2016 1,229,355 $ 3.82 7.6  Issued 1,552,986 25.67  Exercised (162,991) 3.12  Expired/terminated (20,691) 9.14  Stock options outstanding at December 31, 2017 2,598,659 $ 16.88  Vested and expected to vest at December 31, 2017 2,598,659 $ 16.88 8.2  Stock options exercisable at December 31, 2017 831,687 $ 10.99 6.3 
Summary Of Exercise Price Outstanding And Exercisable	   Options Outstanding Options Exercisable  Weighted average  Number remaining contractual Weighted average Number Weighted average  Exercise Price outstanding life (in years) exercise price vested exercise price  $2.67 - $4.28 835,773 6.4 $ 3.72 514,280 $ 3.53  $4.67 - $7.55 261,400 8.7 5.17 75,074 5.15  $12.25 - $19.99 118,000 9.6 19.14 4,603 12.25  $21.55 - $30.99 1,383,486 9.2 26.85 237,730 28.94  2,598,659 8.2 $ 16.88 831,687 $ 10.99 
Schedule Of Fair Value Of Employee Stock Options	   Year Ended December 31,  2017 2016 2015  Expected term in years 0.42 - 6.08 6.08 3.5 - 6.25  Expected volatility 70% - 90% 80% 89% - 90%  Risk-free interest rate 1.00% - 2.20% 1.16% - 1.45% 0.88% - 1.89%  Dividend yield — — — 
Summary Of Stock-Based Compensation Expense	  Year Ended December 31,  2017 2016 2015  General and administrative $ 9,136 $ 674 $ 397  Research and development 1,790 196 5  Total stock-based compensation expense $ 10,926 $ 870 $ 402 
2017 Employee Stock Purchase Plan [Member]
Schedule Of Fair Value Of Employee Stock Options	  Year Ended December 31,  2017  Expected term in years 0.5 - 1.3  Expected volatility 95%  Risk-free interest rate 1.1% - 1.2%  Dividend yield — 

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2017
Income Taxes [Abstract]
Components Of Deferred Tax Assets	   December 31,  2017 2016  Technology $ (863) $ (1,449)  Temporary differences 36 40  Credits 1,536 639  Stock compensation 3,067 272  Net operating loss carryforwards 7,715 5,121  Total deferred tax assets 11,491 4,623  Valuation allowance (11,491) (4,623)  Net deferred tax assets $ — $ — 
Reconcilement Of Tax Rates	   Year Ended December 31,  2017 2016 2015  U.S. federal statutory tax rate (35.0) % (35.0) % (35.0) %  Valuation allowance 23.0 42.0 4.0  Tax reform 18.0 — —  Permanent differences 1.0 2.0 1.0  State tax benefit and other (7.0) (9.0) (7.0)  Effective tax rate — % — % (37.0) % 
Reconciliation Of Unrecognized Tax Benefit Accounts	  December 31,  2017 2016  Balance at the beginning of the year $ 213 $ 66  Gross increases - tax positions in prior periods 37 —  Gross decreases - tax positions in prior periods — —  Gross increases - tax position in current period 262 147  Settlements — —  Lapses in statutes of limitations — —  Balance at the end of the year $ 512 $ 213  

Commitments And Contingencies (

Commitments And Contingencies (Tables)	12 Months Ended
	Dec. 31, 2017
Commitments And Contingencies [Abstract]
Schedule Of Minimum Future Lease Payments Receivable	  Year Ending December 31:  2018 $ 518  2019 536  2020 554  2021 574  2022 392  Thereafter —  $ 2,574 

Selected Quarterly Financial 31

Selected Quarterly Financial Data (Tables)	12 Months Ended
	Dec. 31, 2017
Selected Quarterly Financial Data [Abstract]
Schedule Of Selected Quarterly Financial Data	  Quarter Ended  2017 2016  December 31, September 30, June 30, March 31, December 31, September 30, June 30, March 31,  Revenue $ — $ — $ — $ — $ — $ — $ — $ —  Operating expenses:  General and administrative 5,801 4,434 3,924 1,344 1,027 1,079 665 644  Research and development 2,864 2,925 2,130 1,727 1,649 1,553 1,430 874  Amortization of intangible assets 166 166 167 166 167 166 166 166  Total operating expenses 8,831 7,525 6,221 3,237 2,843 2,798 2,261 1,684  Other income:  Interest income 128 39 41 39 34 31 3 —  Total other income 128 39 41 39 34 31 3 —  Loss from operations, before income taxes (8,703) (7,486) (6,180) (3,198) (2,809) (2,767) (2,258) (1,684)  Income tax benefit — — — — — — — —  Net loss (8,703) (7,486) (6,180) (3,198) (2,809) (2,767) (2,258) (1,684)  Other comprehensive loss:  Unrealized gain (loss) on available-for-sale securities, net of tax: (49) 4 3 (2) 1 (8) — —  Comprehensive loss $ (8,752) $ (7,482) $ (6,177) $ (3,200) $ (2,808) $ (2,775) $ (2,258) $ (1,684)  Net loss per share  Basic and diluted net loss per share $ (0.53) $ (0.52) $ (0.43) $ (0.23) $ (0.21) $ (0.21) $ (0.23) $ (0.22)  Weighted average shares used to compute net loss per common share — basic and diluted 16,574 14,381 14,233 13,803 13,315 13,315 9,791 7,565  

Summary Of Significant Accoun32

Summary Of Significant Accounting Policies (Narrative) (Details) - USD ($)	3 Months Ended							12 Months Ended
	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
Summary Of Significant Accounting Policies [Line Items]
Long-lived asset impairment								$ 0	$ 0	$ 0
Goodwill impairment								0	0	0
Patent related expenses								800,000	500,000	400,000
Liability for uncertain tax positions				$ 0				$ 0	0
Research and development costs reclassified to general and administrative costs	$ 275,000	$ 152,000	$ 124,000	$ 157,000	$ 186,000	$ 23,000	$ 116,000		$ 500,000	$ 400,000
Equipment [Member] | Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Useful life								3 years
Equipment [Member] | Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Useful life								5 years
Acquired Patents And Licenses [Member]
Summary Of Significant Accounting Policies [Line Items]
Intangible asset useful life								12 years

Summary Of Significant Accoun33

Summary Of Significant Accounting Policies (Anti-Dilutive Shares Excluded From Computation 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]
Total	3,078,142	2,103,965	1,174,846
Common Stock Warrants [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total	249,709	874,610	299,625
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total	2,598,659	1,229,355	875,221
Restricted Stock Units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total	229,774

Investments And Fair Value Of34

Investments And Fair Value Of Financial Instruments (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Investments And Fair Value Of Financial Instruments [Abstract]
Impairment on investments	$ 0	$ 0
Transfers between level 1, 2, or 3	$ 0	$ 0

Investments And Fair Value Of35

Investments And Fair Value Of Financial Instruments (Schedule Of Available-For-Sale Securities) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Schedule Of Available For Sale Securities [Line Items]
Cost	$ 34,734	$ 14,312
Gross Unrealized Gains		1
Gross Unrealized Losses	(51)	(7)
Fair Value	34,683	14,306
Commercial Paper [Member]
Schedule Of Available For Sale Securities [Line Items]
Cost	7,216
Gross Unrealized Losses	(6)
Fair Value	7,210
Corporate Bonds [Member]
Schedule Of Available For Sale Securities [Line Items]
Cost	19,524	13,295
Gross Unrealized Gains		1
Gross Unrealized Losses	(33)	(7)
Fair Value	19,491	13,289
Asset-Backed Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Cost	7,994	1,017
Gross Unrealized Losses	(12)
Fair Value	$ 7,982	$ 1,017

Investments And Fair Value Of36

Investments And Fair Value Of Financial Instruments (Schedule Of Contractual Maturities) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Investments And Fair Value Of Financial Instruments [Abstract]
Due in one year	$ 30,096	$ 14,306
Due in one to two years	4,587
Total	$ 34,683	$ 14,306

Investments And Fair Value Of37

Investments And Fair Value Of Financial Instruments (Fair Value Of Financial Assets Measured On A Recurring Basis) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
ASSETS
Total assets measured at fair value	$ 37,441	$ 16,032
Cash And Cash Equivalents [Member] | Money Market Funds [Member]
ASSETS
Total cash and cash equivalents	2,758	1,726
Investments [Member] | Commercial Paper [Member]
ASSETS
Total investments	7,210
Investments [Member] | Corporate Bonds [Member]
ASSETS
Total investments	19,491	13,289
Investments [Member] | Asset-Backed Securities [Member]
ASSETS
Total investments	7,982	1,017
Level 1 [Member]
ASSETS
Total assets measured at fair value	2,758	1,726
Level 1 [Member] | Cash And Cash Equivalents [Member] | Money Market Funds [Member]
ASSETS
Total cash and cash equivalents	2,758	1,726
Level 2 [Member]
ASSETS
Total assets measured at fair value	34,683	14,306
Level 2 [Member] | Investments [Member] | Commercial Paper [Member]
ASSETS
Total investments	7,210
Level 2 [Member] | Investments [Member] | Corporate Bonds [Member]
ASSETS
Total investments	19,491	13,289
Level 2 [Member] | Investments [Member] | Asset-Backed Securities [Member]
ASSETS
Total investments	$ 7,982	$ 1,017

Property And Equipment, Net (Na

Property And Equipment, Net (Narrative) (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Jun. 30, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property And Equipment, Net [Abstract]
Landlord reimbursement of leasehold improvements	$ 2,100
Depreciation and amortization expense		$ 336	$ 94	$ 51

Property And Equipment, Net (Sc

Property And Equipment, Net (Schedule Of Property And Equipment, Net) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Equipment, gross	$ 3,051	$ 462
Less: Accumulated depreciation and amortization	(481)	(145)
Equipment, net	2,570	317
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Equipment, gross	2,257
Laboratory Equipment [Member]
Property, Plant and Equipment [Line Items]
Equipment, gross	484	425
Furniture, Fixtures, And Equipment [Member]
Property, Plant and Equipment [Line Items]
Equipment, gross	231	17
Software [Member]
Property, Plant and Equipment [Line Items]
Equipment, gross	$ 79	$ 20

Intangible Assets, Net (Schedul

Intangible Assets, Net (Schedule Of Intangible Assets, Net) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Less: Accumulated amortization	$ (2,107)	$ (1,442)
Intangible assets, net	5,878	6,543
Acquired Patents And Licenses [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	$ 7,985	$ 7,985

Intangible Assets (Schedule Of

Intangible Assets (Schedule Of Amortization Of Intangible Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Intangible Assets, Net [Abstract]
2,018	$ 665
2,019	666
2,020	665
2,021	666
2,022	665
Thereafter	2,551
Intangible assets, net	$ 5,878	$ 6,543

Goodwill (Narrative) (Details)

Goodwill (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Business Acquisition, Equity Interests Issued or Issuable [Line Items]
Goodwill	$ 2,791	$ 2,791
Goodwill impairment	$ 0	$ 0	$ 0
TPI, BEM And NB [Member]
Business Acquisition, Equity Interests Issued or Issuable [Line Items]
Aggregate consideration				$ 5,500
Goodwill				$ 2,800

Accrued Expenses (Schedule Of A

Accrued Expenses (Schedule Of Accrued Expenses) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Accrued Expenses [Abstract]
Compensation expense	$ 685	$ 261
Professional fees	211	285
Other	73	205
Supplies	65
Accrued expenses	$ 1,034	$ 751

Stockholders' Equity And Stoc44

Stockholders' Equity And Stock-Based Compensation (Narrative) (Details) - USD ($)	Sep. 24, 2017	Feb. 07, 2017	Jan. 31, 2018	Nov. 30, 2017	Jun. 30, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Stockholders' Equity [Line Items]
Common stock, par value						$ 0.001	$ 0.001
Common stock, shares issued						16,819,000	13,315,000
Warrants exercised						162,991
Exercise price						$ 10.99
Aggregate intrinsic value exercisable options						$ 11,800,000
Total intrinsic value of options exercised						3,800,000	$ 0	$ 0
Fair value of options vested						26,800,000	1,200,000	3,100,000
Total stock-based compensation expense						10,926,000	870,000	402,000
Unrecognized compensation cost						$ 22,100,000
Weighted average remaining contractual life						3 years
2017 Equity Incentive Plan [Member]
Stockholders' Equity [Line Items]
Vesting period						10 years
2017 Inducement Equity Incentive Plan [Member]
Stockholders' Equity [Line Items]
Term period						10 years
Shares authorized				1,000,000
First Vesting Portion [Member] | 2017 Inducement Equity Incentive Plan [Member]
Stockholders' Equity [Line Items]
Vesting percentage						25.00%
Second Vesting Portion [Member] | 2017 Inducement Equity Incentive Plan [Member]
Stockholders' Equity [Line Items]
Vesting percentage						8.33%
General And Administrative [Member]
Stockholders' Equity [Line Items]
Total stock-based compensation expense						$ 9,136,000	674,000	397,000
Research And Development [Member]
Stockholders' Equity [Line Items]
Total stock-based compensation expense						$ 1,790,000	$ 196,000	$ 5,000
Common Stock Warrants [Member]
Stockholders' Equity [Line Items]
Warrants exercised						624,901
Aggregate intrinsic value exercisable options						$ 4,900,000
Subsequent Event [Member] | 2017 Employee Stock Purchase Plan [Member]
Stockholders' Equity [Line Items]
Additional common stock reserved for issuance			252,343
Subsequent Event [Member] | 2017 Inducement Equity Incentive Plan [Member]
Stockholders' Equity [Line Items]
Additional common stock reserved for issuance			672,915
Initial Public Offering [Member]
Stockholders' Equity [Line Items]
Proceeds from issuance of common stock					$ 20,300,000
Common stock, shares issued					5,749,846
Directors [Member]
Stockholders' Equity [Line Items]
Total stock-based compensation expense				$ 1,200,000
Underwriters [Member] | Initial Public Offering [Member] | Stock Options [Member]
Stockholders' Equity [Line Items]
Price per share						$ 5
Warrants outstanding						574,985
Exercisable period of warrants or rights						5 years
Expected term						5 years
Expected volatility						80.00%
Dividend yield						0.00%
Underwriters [Member] | Initial Public Offering [Member] | Stock Options [Member] | Minimum [Member]
Stockholders' Equity [Line Items]
Fair value of common stock per share						$ 4.12
Risk-free interest rate						1.22%
Underwriters [Member] | Initial Public Offering [Member] | Stock Options [Member] | Maximum [Member]
Stockholders' Equity [Line Items]
Fair value of common stock per share						$ 4.27
Risk-free interest rate						1.38%
Officer [Member] | Restricted Stock Units [Member]
Stockholders' Equity [Line Items]
Cliff vest date						Jun. 30, 2018
Shares granted						160,974
Total stock-based compensation expense						$ 2,900,000
Unrecognized compensation cost						$ 2,100,000
Certain Employees [Member] | Restricted Stock Units [Member]
Stockholders' Equity [Line Items]
Shares granted						68,800
Total stock-based compensation expense						$ 100,000
Unrecognized compensation cost						$ 1,200,000
Certain Employees [Member] | Restricted Stock Units [Member] | First Vesting Portion [Member]
Stockholders' Equity [Line Items]
Vesting percentage						50.00%
Cliff vest date						Jun. 1, 2019
Certain Employees [Member] | Restricted Stock Units [Member] | Second Vesting Portion [Member]
Stockholders' Equity [Line Items]
Vesting percentage						50.00%
Cliff vest date						Jun. 1, 2021
Certain Employees [Member] | Restricted Stock Units [Member] | Change In Control [Member]
Stockholders' Equity [Line Items]
Vesting percentage						100.00%
Common Stock [Member]
Stockholders' Equity [Line Items]
Shares issued							5,750,000
Warrants exercised						162,000
Number of shares called by issuance of warrants						522,451
Common Stock [Member] | 2017 Equity Incentive Plan [Member]
Stockholders' Equity [Line Items]
Shares authorized						1,500,000
Common Stock [Member] | 2017 Employee Stock Purchase Plan [Member]
Stockholders' Equity [Line Items]
Shares issued						0
Shares authorized						250,000
Additional common stock reserved for issuance						250,000
Common Stock [Member] | 2017 Inducement Equity Incentive Plan [Member]
Stockholders' Equity [Line Items]
Shares authorized						907,000
Common Stock [Member] | Common Stock Warrants [Member]
Stockholders' Equity [Line Items]
Warrants exercised						522,000
Common Stock [Member] | Initial Public Offering [Member]
Stockholders' Equity [Line Items]
Price per share					$ 4
Common Stock [Member] | Private Placement [Member]
Stockholders' Equity [Line Items]
Shares sold	2,000,000	819,673
Common stock, par value	$ 0.001	$ 0.001
Price per share	$ 15.02	$ 6.10
Net proceeds	$ 29,878,000	$ 4,965,000
Shares issued						2,820,000
MDB Capital Group, LLC [Member] | Initial Public Offering [Member]
Stockholders' Equity [Line Items]
Value of warrants						$ 1,400,000

Stockholders' Equity And Stoc45

Stockholders' Equity And Stock-Based Compensation (Summary Of Stock Warrant Activity) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Beginning Balance, Number of shares	1,229,355
Options issued, Number of shares	1,552,986
Options exercised, Number of shares	(162,991)
Options expired/terminated, Number of shares	(20,691)
Ending Balance, Number of shares	2,598,659	1,229,355
Beginning Balance, Weighted average exercise price per share	$ 3.82
Options issued, Weighted average exercise price per share	25.67
Options exercised, Weighted average exercise price per share	3.12
Options expired/terminated, Weighted average exercise price per share	9.14
Ending Balance, Weighted average exercise price per share	$ 16.88	$ 3.82
Weighted average remaining life	8 years 2 months 12 days	7 years 7 months 6 days
Common Stock Warrants [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Beginning Balance, Number of shares	874,610
Options issued, Number of shares
Options exercised, Number of shares	(624,901)
Options expired/terminated, Number of shares
Ending Balance, Number of shares	249,709	874,610
Beginning Balance, Weighted average exercise price per share	$ 4.20
Options issued, Weighted average exercise price per share
Options exercised, Weighted average exercise price per share	4.23
Options expired/terminated, Weighted average exercise price per share
Ending Balance, Weighted average exercise price per share	$ 4.14	$ 4.20
Weighted average remaining life	3 years 6 months 22 days	4 years 6 months 11 days

Stockholders' Equity And Stoc46

Stockholders' Equity And Stock-Based Compensation (Summary Of Stock Option Activity) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Beginning Balance, Number of shares	1,229,355
Options issued, Number of shares	1,552,986
Options exercised, Number of shares	(162,991)
Options expired/terminated, Number of shares	(20,691)
Ending Balance, Number of shares	2,598,659	1,229,355
Vested and expected to vest, Number of shares	2,598,659
Exercisable, Number of shares	831,687
Beginning Balance, Weighted average exercise price per share	$ 3.82
Options issued, Weighted average exercise price per share	25.67
Options exercised, Weighted average exercise price per share	3.12
Options expired/terminated, Weighted average exercise price per share	9.14
Ending Balance, Weighted average exercise price per share	16.88	$ 3.82
Vested and expected to vest, Weighted average exercise price per share	16.88
Exercisable, Weighted average exercise price per share	$ 10.99
Weighted average remaining life	8 years 2 months 12 days	7 years 7 months 6 days
Weighted average remaining life, Vested and expected to vest	8 years 2 months 12 days
Weighted average remaining life, exercisable	6 years 3 months 18 days
$2.67 - $4.28 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercisable, Weighted average exercise price per share	$ 3.53
Weighted average remaining life	6 years 4 months 24 days

Stockholders' Equity And Stoc47

Stockholders' Equity And Stock-Based Compensation (Summary Of Exercise Price Of Stock Options Outstanding And Exercisable) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Number outstanding	2,598,659
Weighted average remaining contractual life (in years)	8 years 2 months 12 days	7 years 7 months 6 days
Weighted average exercise price	$ 16.88
Number vested	831,687
Weighted average exercise price	$ 10.99
$2.67 - $4.28 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise price, lower range	2.67
Exercise price, upper range	$ 4.28
Number outstanding	835,773
Weighted average remaining contractual life (in years)	6 years 4 months 24 days
Weighted average exercise price	$ 3.72
Number vested	514,280
Weighted average exercise price	$ 3.53
$4.67 - $7.55 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise price, lower range	4.67
Exercise price, upper range	$ 7.55
Number outstanding	261,400
Weighted average remaining contractual life (in years)	8 years 8 months 12 days
Weighted average exercise price	$ 5.17
Number vested	75,074
Weighted average exercise price	$ 5.15
$12.25 - $19.99 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise price, lower range	12.25
Exercise price, upper range	$ 19.99
Number outstanding	118,000
Weighted average remaining contractual life (in years)	9 years 7 months 6 days
Weighted average exercise price	$ 19.14
Number vested	4,603
Weighted average exercise price	$ 12.25
$21.55 - $30.99 [Member]
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]
Exercise price, lower range	21.55
Exercise price, upper range	$ 30.99
Number outstanding	1,383,486
Weighted average remaining contractual life (in years)	9 years 2 months 12 days
Weighted average exercise price	$ 26.85
Number vested	237,730
Weighted average exercise price	$ 28.94

Stockholders' Equity And Stoc48

Stockholders' Equity And Stock-Based Compensation (Schedule Of Fair Value Of Employee Stock Options) (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term in years		6 years 29 days
Expected volatility		80.00%
Stock Options [Member] | Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term in years	5 months 1 day		3 years 6 months
Expected volatility	70.00%		89.00%
Risk-free interest rate	1.00%	1.16%	0.88%
Stock Options [Member] | Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term in years	6 years 29 days		6 years 3 months
Expected volatility	90.00%		90.00%
Risk-free interest rate	2.20%	1.45%	1.89%
2017 Employee Stock Purchase Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected volatility	95.00%
2017 Employee Stock Purchase Plan [Member] | Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term in years	6 months
Risk-free interest rate	1.10%
2017 Employee Stock Purchase Plan [Member] | Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term in years	1 year 3 months 18 days
Risk-free interest rate	1.20%

Stockholders' Equity And Stoc49

Stockholders' Equity And Stock-Based Compensation (Summary Of Stock-Based Compensation Expense) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Total stock-based compensation expense	$ 10,926	$ 870	$ 402
General And Administrative [Member]
Total stock-based compensation expense	9,136	674	397
Research And Development [Member]
Total stock-based compensation expense	$ 1,790	$ 196	$ 5

Research Grants And Agreements

Research Grants And Agreements (Narrative) (Details) - USD ($) $ 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
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and development expense	$ 2,864	$ 2,925	$ 2,130	$ 1,727	$ 1,649	$ 1,553	$ 1,430	$ 874	$ 9,646	$ 5,506	$ 2,181
Sponsored Research Agreement ("SRA") [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and development expense									$ 800	900	$ 1,000
ODURF [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Period of time for Sponsored Research Agreement ("SRA")									12 months
ODURF [Member] | Sponsored Research Agreement ("SRA") [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and development budget									$ 370
Research and development expense									740	$ 1,000
Remaining sponsorship	$ 150								150
ODURF And Eastern Virginia Medical School [Member] | Sponsored Research Agreement ("SRA") [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and development expense									$ 300

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Taxes [Line Items]
Income tax provision (benefit)				$ 1,657
Federal statutory tax rate		35.00%	35.00%	35.00%
Total unrecognized tax benefit		$ 512	$ 213	$ 66
Accrued interest or penalties		0	$ 0	$ 0
Reduction in deferred tax assets due to tax act		$ 4,700
Scenario, Plan [Member]
Income Taxes [Line Items]
Federal statutory tax rate	21.00%
Federal And California [Member]
Income Taxes [Line Items]
Net operating loss carryforward, expiration		2,032
Federal [Member]
Income Taxes [Line Items]
Net operating loss carryforwards		$ 25,800
Research and development credit carryforward		$ 1,200
Research and developmen tax credit carryforward, expiration		2,035
California [Member]
Income Taxes [Line Items]
Net operating loss carryforwards		$ 25,900
Research and development credit carryforward		$ 900

Income Taxes (Components Of Def

Income Taxes (Components Of Deferred Tax Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Income Taxes [Abstract]
Technology	$ (863)	$ (1,449)
Temporary differences	36	40
Credits	1,536	639
Stock compensation	3,067	272
Net operating loss carryforwards	7,715	5,121
Total deferred tax assets	11,491	4,623
Valuation allowance	$ (11,491)	$ (4,623)

Income Taxes (Reconcilement Of

Income Taxes (Reconcilement Of Tax Rates) (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Taxes [Abstract]
U.S. federal statutory tax rate	(35.00%)	(35.00%)	(35.00%)
Valuation allowance	23.00%	42.00%	4.00%
Tax reform	18.00%
Permanent differences	1.00%	2.00%	1.00%
State tax benefit and other	(7.00%)	(9.00%)	(7.00%)
Effective tax rate			(37.00%)

Income Taxes (Reconciliation Of

Income Taxes (Reconciliation Of Unrecognized Tax Benefit Accounts) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Income Taxes [Abstract]
Unrecognized tax benefit, Beginning balance	$ 213	$ 66
Gross increases - tax positions in prior periods	37
Gross decreases - tax positions in prior periods
Gross increases - tax position in current period	262	147
Settlements
Lapses in statutes of limitations
Unrecognized tax benefit, Ending balance	$ 512	$ 213

Related Party Transactions (Nar

Related Party Transactions (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended			13 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2015	Nov. 02, 2017	Jun. 30, 2016
Related Party Transaction [Line Items]
Common stock, shares issued	16,819,000	13,315,000
Common stock, par value	$ 0.001	$ 0.001
Patent related expenses	$ 800	$ 500	$ 400
Initial Public Offering [Member]
Related Party Transaction [Line Items]
Common stock, shares issued						5,749,846
MDB Capital Group, LLC [Member] | Initial Public Offering [Member]
Related Party Transaction [Line Items]
Underwriting discounts	1,800
Unaccountable expense reimbursement	200
Value of warrants	$ 1,400
MDB Capital Group, LLC [Member] | Chief Financial Officer [Member]
Related Party Transaction [Line Items]
Officers compensation, monthly				$ 4
Officer compensation		48
Robert W. Duggan [Member] | Board of Directors Chairman [Member]
Related Party Transaction [Line Items]
Common stock, shares issued					2,000,000
Common stock, par value					$ 0.001
Price per share					$ 15.02
Ownership percentage of outstanding securities	35.00%				27.00%
Wilson Sonsini Goodrich And Rosati (WSGR) [Member]
Related Party Transaction [Line Items]
Related party expenses	$ 700
Intellectual Property Related Services [Member] | MDB Capital Group, LLC [Member]
Related Party Transaction [Line Items]
Related party expenses	$ 0	$ 100	26
Executive Search Activities [Member] | MDB Capital Group, LLC [Member]
Related Party Transaction [Line Items]
Related party expenses			49
Offering Related Expenses [Member] | MDB Capital Group, LLC [Member]
Related Party Transaction [Line Items]
Related party expenses			$ 42

Commitments And Contingencies56

Commitments And Contingencies (Narrative) (Details)	Jul. 01, 2017USD ($)$ / mo$ / ft²	Dec. 31, 2017USD ($)ft²$ / mo	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)	Jan. 31, 2017ft²
Commitments and Contingencies [Line Items]
Lease expiration date		Jun. 30, 2017
Operating lease, monthly expense | $ / mo		21,000
Area Of Lease | ft²		4,300			15,700
Lease term	62 months
Security deposit	$ 101,000
Lease renewable term		5 years
Lease obligations, less than one year		$ 518,000
Rent expense, including common area maintenance charges		$ 300,000	$ 200,000	$ 200,000
Maximum [Member]
Commitments and Contingencies [Line Items]
Written notice period for right to extend lease term		12 months
Minimum [Member]
Commitments and Contingencies [Line Items]
Written notice period for right to extend lease term		9 months
Tier One Rent Expense First Two Months Of Lease Term [Member]
Commitments and Contingencies [Line Items]
Operating lease, monthly expense | $ / mo	42,400
Tier Two Rent Expense [Member]
Commitments and Contingencies [Line Items]
Operating lease, monthly expense | $ / mo	50,300
Landlord [Member]
Commitments and Contingencies [Line Items]
Landlord obligatory improvement allowance per rentable square foot | $ / ft²	135
Initial tenant leashold improvements		$ 2,100,000

Commitments And Contingencies57

Commitments And Contingencies (Schedule Of Minimum Future Lease Payments Remaining) (Details) $ in Thousands	Dec. 31, 2017USD ($)
Commitments And Contingencies [Abstract]
2,018	$ 518
2,019	536
2,020	554
2,021	574
2,022	392
Total minimum lease payments	$ 2,574

Employee Benefit Plans (Narrati

Employee Benefit Plans (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Employee Benefit Plans [Abstract]
Employer matching contributions	$ 0	$ 0	$ 0

Selected Quarterly Financial 59

Selected Quarterly Financial Data (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended							12 Months Ended
	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2016	Dec. 31, 2015
Selected Quarterly Financial Data [Abstract]
Research and development costs reclassified to general and administrative costs	$ 275	$ 152	$ 124	$ 157	$ 186	$ 23	$ 116	$ 500	$ 400

Selected Quarterly Financial 60

Selected Quarterly Financial Data (Schedule Of Selected Quarterly Financial Data) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ 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
Selected Quarterly Financial Data [Abstract]
Revenue
Operating expenses:
General and administrative	$ 5,801	$ 4,434	$ 3,924	$ 1,344	$ 1,027	$ 1,079	$ 665	$ 644	15,503	3,415	1,621
Research and development	2,864	2,925	2,130	1,727	1,649	1,553	1,430	874	9,646	5,506	2,181
Amortization of intangible assets	166	166	167	166	167	166	166	166	665	665	666
Total operating expenses	8,831	7,525	6,221	3,237	2,843	2,798	2,261	1,684	25,814	9,586	4,468
Other income:
Interest income	128	39	41	39	34	31	3		247	68
Total other income	128	39	41	39	34	31	3		247	68
Loss from operations, before income taxes	(8,703)	(7,486)	(6,180)	(3,198)	(2,809)	(2,767)	(2,258)	(1,684)	(25,567)	(9,518)	(4,468)
Income tax benefit											(1,657)
Net loss	(8,703)	(7,486)	(6,180)	(3,198)	(2,809)	(2,767)	(2,258)	(1,684)	(25,567)	(9,518)	(2,811)
Other comprehensive loss:
Unrealized gain (loss) on available-for-sale securities, net of tax	(49)	4	3	(2)	1	(8)			(44)	(7)
Comprehensive loss	$ (8,752)	$ (7,482)	$ (6,177)	$ (3,200)	$ (2,808)	$ (2,775)	$ (2,258)	$ (1,684)	$ (25,611)	$ (9,525)	$ (2,811)
Basic and diluted net loss per share	$ (0.53)	$ (0.52)	$ (0.43)	$ (0.23)	$ (0.21)	$ (0.21)	$ (0.23)	$ (0.22)	$ (1.73)	$ (0.86)	$ (0.37)
Weighted average shares used to compute net loss per common share - basic and diluted	16,574	14,381	14,233	13,803	13,315	13,315	9,791	7,565	14,754	11,009	7,565