Pulse Biosciences (PLSE) 10-K 12 Mar 21 2020 FY Annual report Financial data

Document And Entity Information

Document And Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2020	Feb. 28, 2021	Jun. 30, 2020
Document And Entity Information [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2020
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	001-34899
Entity Registrant Name	Pulse Biosciences, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	46-5696597
Entity Address, Address Line One	3957 Point Eden Way
Entity Address, City or Town	Hayward
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94545
City Area Code	510
Local Phone Number	906-4600
Title of 12(b) Security	Common Stock, par value $0.001 per share
Trading Symbol	PLSE
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
ICFR Auditor Attestation Flag	false
Entity Shell Company	false
Entity Public Float			$ 135,220,301
Entity Common Stock, Shares Outstanding		26,086,931
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	FY
Entity Central Index Key	0001625101
Amendment Flag	false
Documents Incorporated by Reference	DOCUMENTS INCORPORATED BY REFERENCE: Portions of the registrant’s definitive Proxy Statement relating to its 2021 Annual Meeting of Stockholders are incorporated by reference into Part III of this Form 10-K where indicated. The Proxy Statement will be filed with the U.S. Securities and Exchange Commission within 120 days after December 31, 2020.

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 12,463	$ 6,899
Investments	8,012	18,499
Prepaid expenses and other current assets	1,864	1,005
Total current assets	22,339	26,403
Property and equipment, net	2,478	2,566
Intangible assets, net	3,882	4,547
Goodwill	2,791	2,791
Right-of-use assets	9,438	5,114
Other assets	365	494
Total assets	41,293	41,915
Current liabilities:
Accounts payable	1,717	1,963
Accrued expenses	5,326	2,496
Lease liability, current	542
Total current liabilities	7,585	4,459
Lease liability, less current portion	10,814	6,719
Total liabilities	18,399	11,178
Commitments and contingencies (Note 10)
Stockholders' equity:
Preferred stock, $0.001 par value; authorized – 50,000 shares; no shares issued and outstanding
Common stock, $0.001 par value; authorized – 500,000 shares; issued and outstanding – 25,550 shares and 20,825 shares at December 31, 2020 and 2019, respectively	25	21
Additional paid-in-capital	195,410	153,401
Accumulated other comprehensive income (loss)	(1)	4
Accumulated deficit	(172,540)	(122,689)
Total stockholders' equity	22,894	30,737
Total liabilities and stockholders' equity	$ 41,293	$ 41,915

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2020	Dec. 31, 2019
Consolidated Balance Sheets [Abstract]
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	50,000,000	50,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	500,000,000	500,000,000
Common stock, shares issued	25,550,000	20,825,000
Common stock, shares outstanding	25,550,000	20,825,000

Consolidated Statements Of Oper

Consolidated Statements Of Operations And Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Consolidated Statements Of Operations And Comprehensive Loss [Abstract]
Revenue
Operating expenses:
General and administrative	22,856	22,327	20,045
Research and development	26,444	24,961	17,253
Amortization of intangible assets	665	666	665
Total operating expenses	49,965	47,954	37,963
Other income:
Interest income	114	983	446
Other			(28)
Total other income	114	983	418
Loss from operations, before income taxes	(49,851)	(46,971)	(37,545)
Income tax benefit
Net loss	(49,851)	(46,971)	(37,545)
Other comprehensive loss:
Unrealized gain (loss) on available-for-sale securities	(5)	5	50
Comprehensive loss	$ (49,856)	$ (46,966)	$ (37,495)
Net loss per share:
Basic and diluted net loss per share	$ (2.14)	$ (2.26)	$ (2.20)
Weighted average shares used to compute net loss per common share - basic and diluted	23,248	20,746	17,078

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Common StockWarrants [Member]	Common StockRights Offering [Member]	Common Stock	Additional Paid-in Capital [Member]Warrants [Member]	Additional Paid-in Capital [Member]Rights Offering [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]Warrants [Member]	Accumulated Other Comprehensive Income (Loss) [Member]Rights Offering [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Deficit [Member]Warrants [Member]	Accumulated Deficit [Member]Rights Offering [Member]	Accumulated Deficit [Member]	Initial Public Offering [Member]Warrants [Member]	Warrants [Member]	Rights Offering [Member]	Total
Balance at Dec. 31, 2017			$ 17			$ 84,202			$ (51)			$ (38,173)				$ 45,995
Balance, shares at Dec. 31, 2017			16,819,000
Shares issued		$ 4			$ 44,782										$ 44,786
Shares issued, shares		3,581,000
Issuance of shares upon exercise of stock options						498										498
Issuance of shares upon exercise of stock options, shares	24,000		145,000
Issuance of shares upon vesting of share-based compensation						327										327
Issuance of shares upon vesting of share-based compensation, shares			24,000
Stock-based compensation expense						12,338										12,338
Tax payments related to shares withheld for vested restricted stock units						(115)										(115)
Unrealized gain (loss) on available-for-sale securities									50							50
Net loss												(37,545)				(37,545)
Balance at Dec. 31, 2018			$ 21			142,032			(1)			(75,718)				66,334
Balance, shares at Dec. 31, 2018			20,593,000
Issuance of shares upon exercise of stock options						272										272
Issuance of shares upon exercise of stock options, shares	37,000		99,000
Issuance of shares under employee stock purchase plan						423										423
Issuance of shares under employee stock purchase plan, shares			38,000
Issuance of shares upon vesting of restriced stock units
Issuance of shares upon vesting of restriced stock units, shares			58,000
Stock-based compensation expense						11,287										11,287
Tax payments related to shares withheld for vested restricted stock units						(613)										(613)
Unrealized gain (loss) on available-for-sale securities									5							5
Net loss												(46,971)				(46,971)
Balance at Dec. 31, 2019			$ 21			153,401			4			(122,689)				$ 30,737
Balance, shares at Dec. 31, 2019			20,825,000													20,825,000
Issuance of shares upon exercise of stock options						887										$ 887
Issuance of shares upon exercise of stock options, shares			175,000										36,224	197,108		175,066
Issuance of shares under employee stock purchase plan						490										$ 490
Issuance of shares under employee stock purchase plan, shares			83,000
Issuance of shares upon exercise of warrants						1,127										1,127
Issuance of shares upon exercise of warrants, shares			187,000
Issuance of common stock and warrants in connection with rights offering, net of issuance cost of $565			$ 4			29,430										29,434
Issuance of common stock and warrants in connection with rights offering, net of issuance cost of $565, shares			4,280,000
Stock-based compensation expense						10,075										10,075
Unrealized gain (loss) on available-for-sale securities									(5)							(5)
Net loss												(49,851)				(49,851)
Balance at Dec. 31, 2020			$ 25			$ 195,410			$ (1)			$ (172,540)				$ 22,894
Balance, shares at Dec. 31, 2020			25,550,000													25,550,000

Consolidated Statements of St_2

Consolidated Statements of Stockholders' Equity (Parenthetical) - Rights [Member] $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)$ / shares
Price per share | $ / shares	$ 12.57
Issuance costs | $	$ 213

Consolidated Statements Of Cash

Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash flows from operating activities:
Net loss	$ (49,851)	$ (46,971)	$ (37,545)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	430	494	645
Amortization of intangible assets	665	666	665
Stock-based compensation	10,075	11,287	12,338
Net premium amortization and discount on available-for-sale securities	5	(521)	(140)
Loss on disposal of fixed assets	119		28
Gain U.S. Treasury securities	(8)
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	194	(226)	(367)
Right-of-use assets	509	68
Other long-term assets	129	(393)
Accounts payable	(266)	646	490
Accrued expenses	2,830	841	387
Lease liabilities	(196)	(76)
Other current and non-current liabilities			(397)
Net cash used in operating activities	(35,365)	(34,185)	(23,896)
Cash flows from investing activities:
Purchases of property and equipment	(441)	(608)	(276)
Purchases of investments	(29,025)	(77,993)	(40,297)
Maturities of investments	35,000	68,500	41,815
Sales of investments	4,510		24,875
Net cash used in investing activities	10,044	(10,101)	26,117
Cash flows from financing activities:
Proceeds from exercises of stock options and warrants	961	272	498
Proceeds from issuance of common stock under employee stock purchase plan	490	423	327
Proceeds from issuance of common stock from rights offering, net of issuance costs of $213	29,434		44,786
Tax payments related to shares withheld for vested restricted stock units		(613)	(115)
Net cash provided by financing activities	30,885	82	45,496
Net increase (decrease) in cash	5,564	(44,204)	47,717
Cash and cash equivalents at beginning of period	6,899	51,103	3,386
Cash and cash equivalents at end of period	12,463	6,899	51,103
Supplemental disclosure of noncash investing and financing activities:
Other receivable from exercise of warrants and stock options	1,053
Change in unrealized gains on available-for-sale securities	(5)	5	50
Unpaid property and equipment included in accounts payable and accrued expenses	$ 20	$ 279	$ 33

Consolidated Statements Of Ca_2

Consolidated Statements Of Cash Flows (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Rights [Member]
Issuance costs	$ 565	$ 213

Description Of The Business

Description Of The Business	12 Months Ended
	Dec. 31, 2020
Description Of The Business [Abstract]
Description Of The Business	1. Description of the Business Pulse Biosciences, Inc. (the Company) is a novel bioelectric medicine company committed to health innovation that improves and potentially extends the lives of patients. The Company’s CellFX System utilizes its patented Nano-Pulse Stimulation™ (NPS™) technology to treat a variety of applications for which an optimal solution remains unfulfilled. NPS is a proprietary technology that delivers nanosecond duration pulses of high amplitude electrical energy to non-thermally clear targeted cells while sparing adjacent non-cellular tissue. The cell-specific effects of NPS technology have been validated in a series of completed and ongoing clinical studies. The Company was incorporated in Nevada on May 19, 2014, and was reincorporated in the State of Delaware on June 18, 2018. 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, 2020
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 of America (U.S. GAAP) and pursuant to the rules and regulations of the United States Securities Exchange Commission (the SEC). The consolidated financial statements include the financial statements of the Company and its wholly-owned subsidiaries and 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 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 investments, clinical trial accruals, the valuation and recognition of stock-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) 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 annual 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 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. No 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 the reporting unit level at least annually or whenever changes in circumstances indicate that the carrying value of the goodwill may not be recoverable. To date, 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 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 grant 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 the stock-based compensation expense 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 simplified method to calculate the expected term, which is the average of the contractual term and vesting period. Prior to the Company’s initial public offering, 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 university research institutes), costs associated with clinical trials, development prototypes and other expenses relating to the acquisition, design, development and testing of the Company’s product candidates, and certain facilities related costs. 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, 2020, 2019 and 2018, patent costs totaled $ 0.5 million, $ 0.6 million and $ 0.6 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 the state of 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, 2020 and 2019, the Company had no t 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 calculates basic net loss per share by dividing net loss by the weighted average number of shares of common stock outstanding during the period. Diluted net loss per share is computed by giving effect to all potential dilutive common stock equivalents outstanding during 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. The following outstanding stock options, warrants and RSUs 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, 2020 2019 2018 Common stock warrants 612,310 167,847 213,485 Common stock options 5,039,194 3,749,186 2,956,687 Restricted stock units 111,305 222,606 222,606 Total 5,762,809 4,139,639 3,392,778 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 (U.S.). Recent Accounting Pronouncements In May 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (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 became effective for the Company in the first quarter of fiscal year 2018 . Since the Company has not recognized or generated revenue to date, the adoption of this pronouncement did not have any impact to its financial statements. In February 2016, the FASB issued ASU No. 2016-02, Leases , amended Accounting Standard Codification (ASC) 842, 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). The Company adopted ASC 842 on January 1, 2019, using the modified retrospective transition method per ASU No. 2018-11 issued on July 2018 wherein entities were allowed to initially apply the new lease standard at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. Accordingly, all periods prior to January 1, 2019 were presented in accordance with ASC 840, Leases , and no retrospective adjustments were made to the comparative periods presented. The adoption of ASC 842 resulted in an increase to total assets and liabilities due to the recording of operating lease right-of-use (ROU) assets presented within other assets and operating lease liabilities of approximately $ 0.1 million as of January 1, 2019. In June 2018, the FASB issued ASU 2018-07, Compensation-Stock Compensation (Topic 718): Improvements to Non-employee Share-Based Payment Accounting, which expands the scope of Topic 718, Compensation—Stock Compensation to include share-based payments issued to non-employees for goods or services. Consequently, the accounting for share-based payments to non-employees and employees will be substantially aligned. The Company adopted ASU 2018-07 in the first quarter of 2019, and the adoption had no significant impact to its financial statements. In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes , which eliminates certain exceptions related to the general principles in ASC 740 and makes amendments to other areas with the intention of simplifying various aspects related to accounting for income taxes. The new standard is effective for fiscal years beginning after December 15, 2020, including interim periods therein; with early adoption permitted. The Company is currently evaluating the impact that the standard will have on its financial statements and related disclosures; and does not expect the adoption to have a material impact on the Company’s financial statements.

Investments And Fair Value Of F

Investments And Fair Value Of Financial Instruments	12 Months Ended
	Dec. 31, 2020
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, 2020 Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value U.S. Treasury securities $ 8,013 $ — $ ( 1 ) $ 8,012 Total assets measured at fair value $ 8,013 $ — $ — $ 8,012 December 31, 2019 Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value U.S. Treasury securities $ 18,495 $ 4 $ — $ 18,499 Total assets measured at fair value $ 18,495 $ 4 $ — $ 18,499 The contractual maturities of the Company’s investments were as follows (in thousands): December 31, Investments 2020 2019 Due in one year $ 8,012 $ 18,499 Due in one to two years — — Total $ 8,012 $ 18,499 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, 2020 Assets Classification Level 1 Level 2 Level 3 Total Money market funds Cash and cash equivalents $ 7,176 — $ — $ 7,176 U.S. Treasury securities Cash and cash equivalents — 2,004 — 2,004 U.S. Treasury securities Investments — 8,012 — 8,012 Total assets measured at fair value $ 7,176 $ 10,016 $ — $ 17,192 December 31, 2019 Assets Classification Level 1 Level 2 Level 3 Total Money market funds Cash and cash equivalents $ 6,429 $ — $ — $ 6,429 U.S. Treasury securities Investments — 18,499 — 18,499 Total assets measured at fair value $ 6,429 $ 18,499 $ — $ 24,928 During year ended December 31, 2020 and 2019, the Company did no t record impairment charges related to its marketable investments. During the years ended December 31, 2020 and 2019, the Company did no t 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, 2020 or 2019.

Balance Sheet Components

Balance Sheet Components	12 Months Ended
	Dec. 31, 2020
Balance Sheet Components [Abstract]
Balance Sheet Components	4. Balance Sheet Components Property and Equipment, net Property and equipment, net consisted of the following (in thousands): December 31, 2020 2019 Leasehold improvements $ 2,805 $ 2,248 Laboratory equipment 878 677 Furniture, fixtures and equipment 517 466 Software 128 118 Construction in progress 66 543 4,394 4,052 Less: Accumulated depreciation and amortization ( 1,916 ) ( 1,486 ) $ 2,478 $ 2,566 The lease for Company’s current premises in Hayward, California began in July 2017, per terms of the lease, the landlord provided $ 2.1 million in tenant improvement allowance which was capitalized. Depreciation and amortization expense for the years ended December 31, 2020, 2019, and 2018 was $ 0.4 million, $ 0.5 million, and $ 0.6 million, respectively. Intangible Assets, net Intangible assets primarily consist of a license to utilize certain patents, know-how and technology relating to the Company’s NPS for biomedical applications acquired from Old Dominion University Research Foundation (ODURF), Eastern Virginia Medical School (EVMS), 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. The Company is amortizing the intangible assets over an estimated useful life of 12 years. Intangible assets, net consisted of the following (in thousands): December 31, 2020 2019 Acquired patents and licenses $ 7,985 $ 7,985 Less: Accumulated amortization ( 4,103 ) ( 3,438 ) $ 3,882 $ 4,547 A schedule of the amortization of intangible assets is as follows (in thousands): Years ending December 31: 2021 $ 665 2022 665 2023 665 2024 665 2025 665 Thereafter 557 $ 3,882 Accrued Expenses Accrued expenses consisted of the following (in thousands): December 31, 2020 2019 Compensation expense $ 3,324 $ 1,699 Director and officer liability insurance (Note 9) 1,563 — Accrued clinical 188 262 Professional fees 87 51 Property and equipment — 234 Other 164 250 $ 5,326 $ 2,496 Accrued compensation expense at December 31, 2019 includes approximately $ 0.3 million relating to the departure of an executive officer, of which the balance was fully paid out in 2020.

Goodwill

Goodwill	12 Months Ended
	Dec. 31, 2020
Goodwill [Abstract]
Goodwill	5. 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, which represents the excess of consideration paid over the fair value of net tangible and intangible assets acquired. The Company reviews goodwill for impairment annually or whenever changes in circumstances indicate that the carrying amount of goodwill may not be recoverable. Based on the Company’s annual review as of December 31, 2020, the Company determined that its goodwill was no t impaired.

Stockholders' Equity And Stock-

Stockholders' Equity And Stock-Based Compensation	12 Months Ended
	Dec. 31, 2020
Stockholders' Equity And Stock-Based Compensation [Abstract]
Stockholders' Equity And Stock-Based Compensation	6. Stockholders’ Equity and Stock-Based Compensation Preferred Stock The Company has authorized a total of 50,000,000 shares of preferred stock, par value $ 0.001 per share, no ne of which were outstanding at December 31, 2020 and 2019. The Company’s Board of Directors (the Board) 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 500,000,000 shares of common stock, par value $ 0.001 per share. Rights Offerings 2018 Rights Offering On October 25, 2018, the Company commenced a rights offering pursuant to which stockholders of record as of November 19, 2018, were issued, at no charge, one subscription right for each share of common stock then outstanding. Each right entitled the holder to purchase 0.19860755 share of the Company’s common stock for $ 12.57 per share (2018 Rights Offering). Stockholders who exercised their rights in full were also permitted an over-subscription right to purchase additional shares of common stock that remained unsubscribed at the expiration of the 2018 Rights Offering, subject to the availability of shares and a pro rata allocation of shares among persons exercising the oversubscription right. Upon the closing of the 2018 Rights Offering on December 6, 2018, the 2018 Rights Offering was oversubscribed. A total of 3,581,148 shares of the Company’s common stock were issued and sold in the 2018 Rights Offering for net proceeds of approximately $ 44.8 million. Robert W. Duggan, the Company’s Chairman of the Board of Directors and the beneficial owner of approximately 35 % of the Company’s outstanding common stock prior to the 2018 Rights Offering, participated in the 2018 Rights Offering and purchased an aggregate of 3,146,226 shares for an additional investment of approximately $ 39.5 million. 2020 Rights Offering During June 2020, the Company completed a rights offering to purchase up to $ 30 million of units, each unit consisting of one share of the Company’s common stock, par value $ 0.001 per share, and 0.15 warrants to purchase shares of common stock (the Units) at a price of $ 7.01 per Unit (2020 Rights Offering). The common stock and warrants comprising the Units separated upon the closing of the 2020 Rights Offering and were issued separately. A total of 4,279,600 shares of common stock and 641,571 warrants (Rights Offering Warrant) were issued and sold in the 2020 Rights Offering for net proceeds of approximately $ 29.4 million. Each warrant is exercisable for one share of the Company’s common stock at an exercise price equal to $ 7.01 , the subscription price for the Units. The Rights Offering Warrants are exercisable immediately and expire on the fifth anniversary of the completion of the 2020 Rights Offering, or June 16, 2025. The Rights Offering Warrants are subject to redemption by the Company for $ 0.01 per warrant, with not less than 30 days written notice, if the volume weighted average price of our common stock equals or exceeds 200 % of the exercise price for the Rights Offering Warrants for 10 consecutive trading days, provided that the Company may not redeem the warrants prior to December 16, 2020, six months after the issuance date. Robert W. Duggan, the Company’s Chairman of the Board of Directors and the beneficial owner of approximately 43 % of the Company’s outstanding common stock prior to the 2020 Rights Offering, participated in the 2020 Rights Offering and purchased an aggregate of 2,561,873 Units. After giving effect to the 2020 Rights Offering, Mr. Duggan is the beneficial owner of approximately 47 % of the Company’s outstanding common stock as of December 31, 2020. Common Stock Warrants In connection with a private placement offering of the Company’s shares of common stock, par value $0.001 per share in 2014, the Company issued warrants as compensation to the placement agent to purchase a total of 299,625 shares of its common stock at a price of $ 2.67 per share (Private Placement Warrants). The Private Placement Warrants are exercisable for a period of seven years . As of December 31, 2020, there were a total of 46,238 of Private Placement Warrants outstanding. In connection with the closing of the Company’s initial public offering in 2016, the Company issued warrants as compensation to its underwriters, as representatives of the underwriters of its initial public offering to purchase a total of 574,985 shares of its common stock at a price of $ 5.00 per share (IPO Warrants). The IPO Warrants are exercisable for a period of five years . As of December 31, 2020, there were a total of 85,385 of the IPO Warrants outstanding . In connection with the 2020 Rights Offering, the Company issued warrants to purchase a total of 641,571 shares of its common stock at an exercise price of $ 7.01 . As of December 31, 2020, there were a total of 480,687 of the Rights Offering Warrants outstanding. On December 31, 2020 the Company met the requirements for redemption of these warrants and delivered a notice of redemption to redeem all of the outstanding warrants that remain unexercised at February 5, 2021, for the redemption price of $ 0.01 per warrant. Pursuant to the redemption, the Company redeemed 5,139 warrants. Prior to the February 5, 2021 redemption date, 636,432 warrants were exercised, generating approximately $ 4.5 million of total gross proceeds to the Company, of which $ 4.2 million was received subsequent to December 31, 2020 and is therefore not included in the cash and cash equivalents balance on the consolidated balance sheet as of December 31, 2020. A summary of total warrants activity for the year ended December 31, 2020 is presented below: Weighted Average Weighted Remaining Number of Average Contractual Shares Exercise Price Life (in Years) Warrants outstanding at December 31, 2019 167,847 $ 4.36 1.28 Issued 641,571 7.01 Exercised ( 197,108 ) 6.64 Expired — — Warrants outstanding and exercisable at December 31, 2020 612,310 $ 6.40 0.26 During the year ended December 31, 2020, IPO Warrants to purchase 36,224 shares of common stock were net exercised, resulting in the issuance of 26,063 shares of common stock. The intrinsic value of exercisable in-the-money stock warrants was approximately $ 10.7 million as of December 31, 2020 . Equity Plans 2017 Equity Incentive Plan and 2017 Inducement Equity Incentive Plan The Board 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, RSUs, 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 may determine. The 2017 Plan is administered by the Board’s Compensation Committee. Subject to an annual evergreen increase and adjustment in the case of certain capitalization events, the Company initially reserved 1,500,000 shares of the Company’s common stock for issuance pursuant to awards under the 2017 Plan. In addition, shares remaining available under the Company’s 2015 Equity Incentive Plan, as amended (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. Effective January 1, 2020 and 2019, the number of shares of common stock available under the 2017 Plan increased by 833,018 and 823,716 shares, respectively, pursuant to the evergreen provision of the 2017 Plan. Under the evergreen provision of the 2017 Plan, the share increase is determined based on the least of (i) 1,200,000 shares, (ii) 4 % of the Company’s common stock outstanding at December 31 of the immediately preceding year, or (iii) such number of shares as determined by the Board. As of December 31, 2020, 465,899 shares of common stock remained available for issuance under the 2017 Plan. During November 2017, the Board of the Company adopted the 2017 Inducement Equity Incentive Plan (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 non-statutory stock options, RSUs, restricted stock, stock appreciation rights, performance shares and performance units, and its terms are substantially similar to the 2017 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 % annually over four years . 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, 2020, 11,158 shares of common stock were available for issuance under the Inducement Plan. Certain stock options awarded to the Company’s executives and other key employees contain performance conditions related to certain financial measures and achievements of strategic/operational milestones (performance options). As of December 31, 2020, not all of the performance conditions are probable to be achieved. Compensation expense has only been recognized for those conditions that are assumed to be probable. 2017 Employee Stock Purchase Plan The Board previously adopted and the stockholders approved the Company’s 2017 Employee Stock Purchase Plan (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 were available for purchase at adoption of the 2017 ESPP. At meetings in February 2020 and January 2019, the Board determined not to increase the number of shares of common stock available under the 2017 ESPP pursuant to the evergreen provision of the 2017 ESPP. Pursuant to the 2017 ESPP, the annual share increase pursuant to the evergreen provision is determined based on the least of (i) 450,000 shares, (ii) 1.5 % of the Company’s common stock outstanding at December 31 of the immediately preceding year, or (iii) such number of shares as determined by the Board. During the year ended December 31, 2020 and 2019, the Company issued 82,971 and 38,279 shares of common stock under the 2017 ESPP, respectively. As of December 31, 2020, 357,224 shares of common stock remained available for issuance under the 2017 ESPP. A summary of stock option activity under the 2015 Plan, 2017 Plan and Inducement Plan for the year ended December 31, 2020 is presented below: Weighted Weighted Average Average Remaining Number of Exercise Contractual Shares Price Life (in Years) Balances - December 31, 2019 3,749,186 $ 16.18 7.90 Options granted 1,973,810 10.19 Options exercised ( 175,066 ) 5.07 Options canceled ( 351,234 ) 12.71 Options expired ( 157,502 ) 23.64 Balances - December 31, 2020 5,039,194 $ 14.26 7.83 Stock options exercisable at December 31, 2020 2,552,230 $ 17.03 6.60 The intrinsic value of stock options exercised during the year ended December 31, 2020, 2019 and 2018 was $ 1.6 million, $ 1.0 million, and $ 1.8 million, respectively. The fair value of employee stock options was estimated using the Black-Scholes option-pricing model utilizing the following assumptions: Year Ended December 31, 2020 2019 2018 Expected term in years 5.3 - 6.1 0.4 - 6.1 5.3 - 6.1 Expected volatility 70 % 70 % 70 % Risk-free interest rate 0.3 - 0.5 % 1.4 - 2.6 % 2.6 - 3.0 % Dividend yield — — — The fair value of the stock options granted to employees and directors during the years ended December 31, 2020, 2019 and 2018 was $ 6.7 million, $ 8.4 million, and $ 6.4 million, respectively. The fair value of ESPP was estimated using the Black-Scholes option-pricing model utilizing the following assumptions: Year Ended December 31, 2020 2019 2018 Expected term in years 0.5 - 1.0 0.5 - 1.0 0.5 - 1.0 Expected volatility 70 % 70 % 70 % Risk-free interest rate 0.1 % - 1.0 % 1.7 % - 2.6 % 1.9 % - 2.5 % Dividend yield — — — Total stock-based compensation expense was as follows (in thousands): Year Ended December 31, 2020 2019 2018 General and administrative $ 6,062 $ 7,466 $ 9,004 Research and development 4,013 3,821 3,334 Total stock-based compensation expense $ 10,075 $ 11,287 $ 12,338 The fair value of RSU 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 all of which vested in June 2018 pursuant to which no shares were issued. Additional paid in capital was reduced by $ 0.1 million for tax payments related to shares withheld in connection with the vesting of the RSUs. There was no stock-based compensation expense related to these RSUs recorded in the years ended December 31, 2020 and 2019, and approximately $ 2.1 million in the year ended December 31, 2018. As of December 31, 2020, there was no unrecognized compensation expense related to these RSUs. During the year ended December 31, 2017, the Company granted 68,800 RSUs to certain employees, of which 50 % vested 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 the years ended December 31, 2020, 2019, and 2018 related to these RSUs was approximately $ 0.3 million, $ 0.4 million, and $ 0.4 million, respectively. As of December 31, 2020, there was $ 0.1 million of unrecognized compensation expense related to these RSUs. At December 31, 2020, there was $ 9.6 million of unrecognized compensation cost related to unvested stock-based compensation arrangements, which is expected to be recognized over a weighted average period of 2.5 years.

Research Grants And Agreements

Research Grants And Agreements	12 Months Ended
	Dec. 31, 2020
Research Grants And Agreements [Abstract]
Research Grants And Agreements	7. Research Grants and Agreements Sponsored Research Agreement The Company entered into a Sponsored Research Agreement (SRA) with 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 each of the years ended December 31, 2019 and 2018, the Company agreed to sponsor $ 0.8 million 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, 2020, there is no remaining balance payable under this research agreement. During the years ended December 31, 2020, 2019 and 2018, the Company incurred costs relating to the SRA equal to $ 0.6 million, $ 0.9 million and $ 0.7 million, respectively.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2020
Income Taxes [Abstract]
Income Taxes	8. Income Taxes Income (loss) before income taxes during the years ended December 31, 2020 and 2019 is as follows (in thousands): December 31, 2020 2019 2018 Domestic $ ( 49,851 ) $ ( 46,971 ) $ ( 37,545 ) Foreign — — — $ ( 49,851 ) $ ( 46,971 ) $ ( 37,545 ) The components of the provision for income taxes are as follows (in thousands): December 31, 2020 2019 2018 Current Federal $ — $ — $ — State 3 3 3 Foreign — — — Total current 3 3 3 Deferred Federal — — — State — — — Foreign — — — Total deferred — — — Total provision for income taxes $ 3 $ 3 $ 3 The provision for income taxes differs from the amount estimated by applying the statutory federal income tax rate to income (loss) before taxes as follows: Year Ended December 31, 2020 2019 2018 Federal tax (benefit) at statutory rate 21.0 % 21.0 % 21.0 % State tax (benefit) at statutory rate 8.4 ( 5.0 ) 7.0 Research and development credits 2.1 2.0 ( 2.0 ) Change in valuation allowance ( 43.3 ) ( 18.0 ) ( 28.0 ) Deferred adjustment 8.5 — — Change in tax rate 4.2 — — Tax reform — — 2.0 Other ( 0.8 ) — — Provision for income taxes — % — % — % Note that for presentation purposes, the 2019 and 2018 percentages have been changed to present the opposite value from what was previously disclosed to allow for proper comparability to current year percentages. Deferred income taxes reflect the impact of carryforwards and temporary differences between the amounts of assets and liabilities for financial reporting purposes and such amounts as measured by tax laws. The carryforwards and temporary differences, which give rise to a significant portion of the Company's deferred tax asset (liability) as of December 31, 2020 and 2019, are as follows (in thousands): December 31, 2020 2019 Deferred tax assets Accruals $ 894 $ 119 Net operating loss carryforwards 36,531 20,755 Tax credit carryforwards 5,431 4,409 Stock-based compensation 9,391 5,473 Lease liability under ASC 842 3,339 1,411 Gross deferred tax assets 55,586 32,167 Valuation allowance ( 51,973 ) ( 30,369 ) Total deferred tax assets 3,613 1,798 Deferred tax liabilities Intangibles ( 486 ) ( 434 ) ROU asset under ASC 842 ( 3,096 ) ( 1,364 ) Fixed assets ( 31 ) — Total deferred tax liabilities ( 3,613 ) ( 1,798 ) Net deferred tax assets/(liabilities) $ — $ — The Company's unrecognized tax benefits as of December 31, 2020, 2019, and 2018 were $ 2.5 million, $ 1.5 million, and $ 0.9 million, respectively. If recognized, none of the unrecognized tax benefits would impact income tax expense to the extent that the Company continues to maintain a full valuation allowance against its deferred tax assets. A reconciliation of the beginning and ending amounts of unrecognized tax benefit is as follows (in thousands): December 31, 2020 2019 2018 Unrecognized tax benefits at beginning of year $ 1,470 $ 877 $ 512 Increases related to current year tax positions 1,021 593 365 Unrecognized tax benefits at end of year $ 2,491 $ 1,470 $ 877 The Company’s policy is to recognize interest and penalties related to income taxes as components of interest expense and other expense, respectively. The Company did not accrue interest and penalties related to unrecognized tax benefits as of December 31, 2020 and does not anticipate any significant change within twelve months of this reporting date. The Company's valuation allowance increased by $ 21.6 million in the year ended December 31, 2020 and increased by $ 7.7 million in the year ended December 31, 2019. As of December 31, 2020, the Company had federal and state net operating loss carryforwards of $ 125 million and $ 117 million, respectively, which begin to expire in 2034 . Of the total federal net operating loss (NOL) carryforward of $ 125 million, approximately $ 99 million is carried forward indefinitely but is limited to 80 % of the taxable income. As of December 31, 2020, the Company had approximately $ 4.2 million and $ 3.8 million of U.S. federal and California research and development (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. The Company is subject to taxation in the United States for Federal and State. All jurisdictions and tax years currently remain open for IRS and state taxing authorities’ examination. As of December 31, 2020, the Company was not under examination by the Internal Revenue Service or any state tax jurisdiction. Internal Revenue Code Section 382 ownership change generally occurs if one or more stockholders or groups of stockholders who own at least 5% of our stock increase their ownership by more than 50 percentage points over their lowest ownership percentage within a rolling three-year period. Similar rules may apply under state tax laws. The Company is not aware of any ownership changes in this financial period ending on December 31, 2020. The Coronavirus Aid, Relief, and Economic Security Act (CARES Act) was enacted on March 27, 2020 in the U.S. The CARES Act and related notices include several significant provisions, including delaying certain payroll tax payments, mandatory transition tax payments under the Tax Cut and Jobs Act, and estimated income tax payments that the Company is deferring to future periods. The Consolidated Appropriations Act (CAA) was also enacted on December 27, 2020 to provide further relief measures and renew various expiring tax provisions. The CARES Act and CAA are not expected to have a significant impact on the Company’s effective tax rate, cash expense, or net deferred tax assets.

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2020
Related Party Transactions [Abstract]
Related Party Transactions	9. Related Party Transactions Kenneth A. Clark, a director of the Company since November 2017, is a member of the law firm of Wilson Sonsini Goodrich and Rosati (WSGR), which also serves as the outside corporate counsel to the Company. During the years ended December 31, 2020, 2019 and 2018, the Company incurred expenses reported in general and administrative expenses in the consolidated statement of operations for legal services rendered by WSGR totaling approximately $ 0.8 million, $ 0.5 million and $ 1.2 million, respectively. During the year ended December 31, 2020, the Company capitalized approximately $ 0.4 million for legal expenses incurred in connection with the 2020 rights offering. During the year ended December 31, 2018, the Company capitalized approximately $ 0.1 million for legal expenses incurred in connection with the 2018 rights offering (Note 6). During December 2018, the Company completed a rights offering pursuant to which it sold an aggregate of 3,581,148 shares of its common stock, par value $ 0.001 per share, at a price per share of $ 12.57 , for net proceeds of approximately $ 44.8 million. At the time of transaction, Robert W. Duggan, the Company’s Chairman of the Board of Directors and the beneficial owner of approximately 35 % of the Company’s then outstanding common stock prior to the rights offering. Mr. Duggan purchased an aggregate of 3,146,226 shares of common stock which increased his beneficial ownership to approximately 43 % of the Company’s outstanding stock at the time. During June 2020, the Company completed a rights offering to purchase up to $ 30 million of units, each unit consisting of one share of the Company’s common stock, par value $ 0.001 per share, and 0.15 warrants to purchase shares of common stock at a price of $ 7.01 per Unit. A total of 4,279,600 shares of its common stock, par value $ 0.001 per share, and 641,571 warrants were issued and sold in the 2020 Rights Offering for net proceeds of $ 29.4 million. Robert W. Duggan, the Company’s Chairman of the Board of Directors and the beneficial owner of approximately 43 % of the Company’s outstanding common stock prior to the 2020 Rights Offering, participated in the 2020 Rights Offering and purchased an aggregate of 2,561,873 Units. After giving effect to the 2020 Rights Offering, Mr. Duggan was the beneficial owner of approximately 47 % of the Company’s outstanding stock as of December 31, 2020. The Company determined not to renew its director and officer liability insurance policies due to disproportionately high premiums quoted by insurance companies. Instead, Robert W. Duggan and the Company entered into a letter agreement, dated May 12, 2020 (the Letter Agreement), pursuant to which Mr. Duggan agreed with the Company to personally provide indemnity coverage on substantially the same terms as the Company’s prior coverage program for a one-year period, and has deposited $ 30 million of cash as security for such obligations. The Company will pay a fee of $ 2.5 million to Mr. Duggan that shall be due on May 13, 2021, the last day of the one-year period, in consideration of the obligations set forth in the Letter Agreement. The other members of the Board are third-party beneficiaries under the Agreement. As of December 31, 2020, the amount owed to Mr. Duggan under the Letter Agreement was $ 1.6 million, recorded in the balance sheet under Accrued Liabilities.

Commitments And Contingencies

Commitments And Contingencies	12 Months Ended
	Dec. 31, 2020
Commitments And Contingencies [Abstract]
Commitments And Contingencies	10. Commitments and Contingencies Operating Leases During January 2017, the Company entered into a five-year lease (the Existing Lease) for approximately 15,700 square feet for its corporate headquarters located in Hayward, California. The lease commenced during July 2017. During May 2019, the Company entered into Lease Amendment 1 (the Amendment) in relation to the Existing Lease and added the lease of new premises of approximately 13,300 square feet and 21,300 square feet, (Expansion Premises 1 and Expansion Premises 2, respectively). Additionally, the term of the Existing Lease was extended to be coterminous with Expansion Premises 1 and Expansion Premises 2, effective October 2029. The Company evaluated the lease amendment under the provisions of ASC 842. It concluded that the Amendment would be accounted for as a single contract with the Existing Lease because the additional lease payments due to the Amendment was not commensurate with ROU asset granted to the Company. Though the Amendment was accounted for as a single contract, the Existing Premises, Expansion Premises 1 (occupied in November 2019) and Expansion Premises 2 (occupied in May 2020) are accounted for as separate lease components. Accordingly, the Company measured and allocated consideration to each lease component as of the modification date. Upon commencement of each lease component, the Company reassessed and calculated the lease liability and ROU asset for the respective component. As a result, at the modification date, the Company remeasured its existing lease liability and recorded an additional ROU asset and lease liability of $ 2.0 million . The Company also recorded an additional ROU asset and lease liability of $ 3.0 million and $ 4.8 million at the commencement of Expansion Premises 1 in November 2019 and Expansion Premises 2 in May 2020, respectively. At December 31, 2020, total ROU assets and lease lability including the impact of ASC 842 adoption, was approximately $ 9.4 million and $ 11.4 million , respectively. During the years ended December 31, 2020, 2019 and 2018, rent expense, including common area maintenance charges, was $ 1.7 million, $ 0.5 million and $ 0.2 million, respectively. Information related to the Company's ROU assets and related lease liabilities were as follows (in thousands except for remaining lease term and discount rate): Year ending December 31: 2021 $ 1,643 2022 1,806 2023 1,845 2024 1,910 Thereafter 10,214 Total lease payments 17,418 Less imputed interest ( 6,062 ) Total lease liabilities $ 11,356 Other supplemental non-cash information: Cash paid for operating lease liabilities $ 1,045 Operating lease liabilities arising from ROU assets $ 4,833 Current operating lease liabilities 542 Non-current operating lease liabilities 10,814 Total lease liabilities $ 11,356 Weighted-average remaining lease term 8.83 Weighted-average discount rate 10 % Indemnification 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. 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, 2020
Employee Benefit Plans [Abstract]
Employee Benefit Plans	11. Employee Benefit Plans The Company sponsors a defined contribution plan under which it may make discretionary contributions. The Company did no t make any employer matching contributions to this plan during the years ended December 31, 2020, 2019 and 2018.

Subsequent Events

Subsequent Events	12 Months Ended
	Dec. 31, 2020
Subsequent Events [Abstract]
Subsequent Events	13. Subsequent Events In February 2021 the Company filed an at-the-market equity offering with the SEC, having an aggregate offering price of up to $ 60 million under which the Company may offer and sell shares of the Company’s common stock from time to time, although the Company has no obligation to make sales pursuant to such at-the-market equity offering . On March 11, 2021, the Company and Robert W. Duggan, principal stockholder and Chairman of the board of directors, entered into a Loan Agreement in connection with Mr. Duggan lending the principal sum of $ 41.0 million to the Company. The Loan Agreement bears interest at a rate per annum equal to 5.0 %, payable quarterly commencing on July 1, 2021. The interest rate payable under the Loan Agreement increases to 7.0 % upon the occurrence of an Event of Default or a Material Adverse Effect, each as defined in the Loan Agreement. All unpaid principal amount of the Loan Agreement, together with any then unpaid and accrued interest, shall be payable at the earlier of (i) June 11, 2022 or (ii) when, upon the occurrence and during the continuance of an Event of Default, such amounts are declared due and payable by Mr. Duggan or made automatically due and payable, in each case, in accordance with the terms thereof, including any applicable cure periods as set forth in the Loan Agreement. A late payment fee equal to 2.0 % will be applied to any payments received later than one (1) business day after the expiration of the applicable cure period. Upon five business days prior written notice to Mr. Duggan, the Company may prepay all or any portion of the amounts borrowed under the Loan Agreement, without premium or penalty. The Loan Agreement subjects the Company to certain affirmative and negative covenants. In addition, the Loan Agreement contains certain Events of Default.

Summary Of Significant Accoun_2

Summary Of Significant Accounting Policies (Policy)	12 Months Ended
	Dec. 31, 2020
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 of America (U.S. GAAP) and pursuant to the rules and regulations of the United States Securities Exchange Commission (the SEC). The consolidated financial statements include the financial statements of the Company and its wholly-owned subsidiaries and 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 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 investments, clinical trial accruals, the valuation and recognition of stock-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) 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 annual 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 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. No 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 the reporting unit level at least annually or whenever changes in circumstances indicate that the carrying value of the goodwill may not be recoverable. To date, 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 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 grant 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 the stock-based compensation expense 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 simplified method to calculate the expected term, which is the average of the contractual term and vesting period. Prior to the Company’s initial public offering, 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 university research institutes), costs associated with clinical trials, development prototypes and other expenses relating to the acquisition, design, development and testing of the Company’s product candidates, and certain facilities related costs. 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, 2020, 2019 and 2018, patent costs totaled $ 0.5 million, $ 0.6 million and $ 0.6 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 the state of 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, 2020 and 2019, the Company had no t 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 calculates basic net loss per share by dividing net loss by the weighted average number of shares of common stock outstanding during the period. Diluted net loss per share is computed by giving effect to all potential dilutive common stock equivalents outstanding during 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. The following outstanding stock options, warrants and RSUs 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, 2020 2019 2018 Common stock warrants 612,310 167,847 213,485 Common stock options 5,039,194 3,749,186 2,956,687 Restricted stock units 111,305 222,606 222,606 Total 5,762,809 4,139,639 3,392,778
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 (U.S.).
Recent Accounting Pronouncement	Recent Accounting Pronouncements In May 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (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 became effective for the Company in the first quarter of fiscal year 2018 . Since the Company has not recognized or generated revenue to date, the adoption of this pronouncement did not have any impact to its financial statements. In February 2016, the FASB issued ASU No. 2016-02, Leases , amended Accounting Standard Codification (ASC) 842, 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). The Company adopted ASC 842 on January 1, 2019, using the modified retrospective transition method per ASU No. 2018-11 issued on July 2018 wherein entities were allowed to initially apply the new lease standard at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. Accordingly, all periods prior to January 1, 2019 were presented in accordance with ASC 840, Leases , and no retrospective adjustments were made to the comparative periods presented. The adoption of ASC 842 resulted in an increase to total assets and liabilities due to the recording of operating lease right-of-use (ROU) assets presented within other assets and operating lease liabilities of approximately $ 0.1 million as of January 1, 2019. In June 2018, the FASB issued ASU 2018-07, Compensation-Stock Compensation (Topic 718): Improvements to Non-employee Share-Based Payment Accounting, which expands the scope of Topic 718, Compensation—Stock Compensation to include share-based payments issued to non-employees for goods or services. Consequently, the accounting for share-based payments to non-employees and employees will be substantially aligned. The Company adopted ASU 2018-07 in the first quarter of 2019, and the adoption had no significant impact to its financial statements. In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes , which eliminates certain exceptions related to the general principles in ASC 740 and makes amendments to other areas with the intention of simplifying various aspects related to accounting for income taxes. The new standard is effective for fiscal years beginning after December 15, 2020, including interim periods therein; with early adoption permitted. The Company is currently evaluating the impact that the standard will have on its financial statements and related disclosures; and does not expect the adoption to have a material impact on the Company’s financial statements.

Summary Of Significant Accoun_3

Summary Of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2020
Summary Of Significant Accounting Policies [Abstract]
Anti-Dilutive Shares Excluded From Computation Of Diluted Net Loss Per Share	Year Ended December 31, 2020 2019 2018 Common stock warrants 612,310 167,847 213,485 Common stock options 5,039,194 3,749,186 2,956,687 Restricted stock units 111,305 222,606 222,606 Total 5,762,809 4,139,639 3,392,778

Investments And Fair Value Of_2

Investments And Fair Value Of Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2020
Investments And Fair Value Of Financial Instruments [Abstract]
Schedule Of Available-For-Sale Securities	December 31, 2020 Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value U.S. Treasury securities $ 8,013 $ — $ ( 1 ) $ 8,012 Total assets measured at fair value $ 8,013 $ — $ — $ 8,012 December 31, 2019 Cost Gross Unrealized Gains Gross Unrealized Losses Fair Value U.S. Treasury securities $ 18,495 $ 4 $ — $ 18,499 Total assets measured at fair value $ 18,495 $ 4 $ — $ 18,499
Schedule Of Contractual Maturities	December 31, Investments 2020 2019 Due in one year $ 8,012 $ 18,499 Due in one to two years — — Total $ 8,012 $ 18,499
Fair Value Of Financial Assets Measured On A Recurring Basis	December 31, 2020 Assets Classification Level 1 Level 2 Level 3 Total Money market funds Cash and cash equivalents $ 7,176 — $ — $ 7,176 U.S. Treasury securities Cash and cash equivalents — 2,004 — 2,004 U.S. Treasury securities Investments — 8,012 — 8,012 Total assets measured at fair value $ 7,176 $ 10,016 $ — $ 17,192 December 31, 2019 Assets Classification Level 1 Level 2 Level 3 Total Money market funds Cash and cash equivalents $ 6,429 $ — $ — $ 6,429 U.S. Treasury securities Investments — 18,499 — 18,499 Total assets measured at fair value $ 6,429 $ 18,499 $ — $ 24,928

Balance Sheet Components (Table

Balance Sheet Components (Tables)	12 Months Ended
	Dec. 31, 2020
Balance Sheet Components [Abstract]
Schedule Of Property And Equipment, Net	December 31, 2020 2019 Leasehold improvements $ 2,805 $ 2,248 Laboratory equipment 878 677 Furniture, fixtures and equipment 517 466 Software 128 118 Construction in progress 66 543 4,394 4,052 Less: Accumulated depreciation and amortization ( 1,916 ) ( 1,486 ) $ 2,478 $ 2,566
Schedule Of Intangible Assets, Net	December 31, 2020 2019 Acquired patents and licenses $ 7,985 $ 7,985 Less: Accumulated amortization ( 4,103 ) ( 3,438 ) $ 3,882 $ 4,547
Schedule Of Amortization Of Intangible Assets	Years ending December 31: 2021 $ 665 2022 665 2023 665 2024 665 2025 665 Thereafter 557 $ 3,882
Schedule Of Accrued Expenses	December 31, 2020 2019 Compensation expense $ 3,324 $ 1,699 Director and officer liability insurance (Note 9) 1,563 — Accrued clinical 188 262 Professional fees 87 51 Property and equipment — 234 Other 164 250 $ 5,326 $ 2,496

Stockholders' Equity And Stoc_2

Stockholders' Equity And Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2020
Stockholders' Equity [Line Items]
Summary Of Stock Warrant Activity	Weighted Average Weighted Remaining Number of Average Contractual Shares Exercise Price Life (in Years) Warrants outstanding at December 31, 2019 167,847 $ 4.36 1.28 Issued 641,571 7.01 Exercised ( 197,108 ) 6.64 Expired — — Warrants outstanding and exercisable at December 31, 2020 612,310 $ 6.40 0.26
Summary Of Stock Option Activity	Weighted Weighted Average Average Remaining Number of Exercise Contractual Shares Price Life (in Years) Balances - December 31, 2019 3,749,186 $ 16.18 7.90 Options granted 1,973,810 10.19 Options exercised ( 175,066 ) 5.07 Options canceled ( 351,234 ) 12.71 Options expired ( 157,502 ) 23.64 Balances - December 31, 2020 5,039,194 $ 14.26 7.83 Stock options exercisable at December 31, 2020 2,552,230 $ 17.03 6.60
Summary Of Stock-Based Compensation Expense	Year Ended December 31, 2020 2019 2018 General and administrative $ 6,062 $ 7,466 $ 9,004 Research and development 4,013 3,821 3,334 Total stock-based compensation expense $ 10,075 $ 11,287 $ 12,338
Employee Stock Option [Member]
Stockholders' Equity [Line Items]
Schedule Of Fair Value Of Employee Stock Options	Year Ended December 31, 2020 2019 2018 Expected term in years 5.3 - 6.1 0.4 - 6.1 5.3 - 6.1 Expected volatility 70 % 70 % 70 % Risk-free interest rate 0.3 - 0.5 % 1.4 - 2.6 % 2.6 - 3.0 % Dividend yield — — —
2017 Employee Stock Purchase Plan [Member]
Stockholders' Equity [Line Items]
Schedule Of Fair Value Of Employee Stock Options	Year Ended December 31, 2020 2019 2018 Expected term in years 0.5 - 1.0 0.5 - 1.0 0.5 - 1.0 Expected volatility 70 % 70 % 70 % Risk-free interest rate 0.1 % - 1.0 % 1.7 % - 2.6 % 1.9 % - 2.5 % Dividend yield — — —

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2020
Income Taxes [Abstract]
Income (Loss) Before Income Taxes	December 31, 2020 2019 2018 Domestic $ ( 49,851 ) $ ( 46,971 ) $ ( 37,545 ) Foreign — — — $ ( 49,851 ) $ ( 46,971 ) $ ( 37,545 )
Components of Income Tax Expense (Benefit)	December 31, 2020 2019 2018 Current Federal $ — $ — $ — State 3 3 3 Foreign — — — Total current 3 3 3 Deferred Federal — — — State — — — Foreign — — — Total deferred — — — Total provision for income taxes $ 3 $ 3 $ 3
Reconcilement Of Tax Rates	Year Ended December 31, 2020 2019 2018 Federal tax (benefit) at statutory rate 21.0 % 21.0 % 21.0 % State tax (benefit) at statutory rate 8.4 ( 5.0 ) 7.0 Research and development credits 2.1 2.0 ( 2.0 ) Change in valuation allowance ( 43.3 ) ( 18.0 ) ( 28.0 ) Deferred adjustment 8.5 — — Change in tax rate 4.2 — — Tax reform — — 2.0 Other ( 0.8 ) — — Provision for income taxes — % — % — %
Components Of Deferred Tax Assets	December 31, 2020 2019 Deferred tax assets Accruals $ 894 $ 119 Net operating loss carryforwards 36,531 20,755 Tax credit carryforwards 5,431 4,409 Stock-based compensation 9,391 5,473 Lease liability under ASC 842 3,339 1,411 Gross deferred tax assets 55,586 32,167 Valuation allowance ( 51,973 ) ( 30,369 ) Total deferred tax assets 3,613 1,798 Deferred tax liabilities Intangibles ( 486 ) ( 434 ) ROU asset under ASC 842 ( 3,096 ) ( 1,364 ) Fixed assets ( 31 ) — Total deferred tax liabilities ( 3,613 ) ( 1,798 ) Net deferred tax assets/(liabilities) $ — $ —
Reconciliation Of Unrecognized Tax Benefit Accounts	December 31, 2020 2019 2018 Unrecognized tax benefits at beginning of year $ 1,470 $ 877 $ 512 Increases related to current year tax positions 1,021 593 365 Unrecognized tax benefits at end of year $ 2,491 $ 1,470 $ 877

Commitments And Contingencies (

Commitments And Contingencies (Tables)	12 Months Ended
	Dec. 31, 2020
Commitments And Contingencies [Abstract]
Schedule Of Maturity Lease Payments And Information Related To Right-Of-Use Assets And Lease Liabilities	Year ending December 31: 2021 $ 1,643 2022 1,806 2023 1,845 2024 1,910 Thereafter 10,214 Total lease payments 17,418 Less imputed interest ( 6,062 ) Total lease liabilities $ 11,356 Other supplemental non-cash information: Cash paid for operating lease liabilities $ 1,045 Operating lease liabilities arising from ROU assets $ 4,833 Current operating lease liabilities 542 Non-current operating lease liabilities 10,814 Total lease liabilities $ 11,356 Weighted-average remaining lease term 8.83 Weighted-average discount rate 10 %

Summary Of Significant Accoun_4

Summary Of Significant Accounting Policies (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Jan. 01, 2019	Dec. 31, 2017
Summary Of Significant Accounting Policies [Line Items]
Accumulated deficit	$ (172,540,000)	$ (122,689,000)
Stockholders Equity	22,894,000	30,737,000	$ 66,334,000		$ 45,995,000
Cash used in operating activities	(35,365,000)	(34,185,000)	(23,896,000)
General and administrative	22,856,000	22,327,000	20,045,000
Long-lived asset impairment	$ 0	0	0
Intangible asset useful life	12 years
Patent costs	$ 500,000	600,000	600,000
Liability for Uncertainty in Income Taxes, Noncurrent	0	0
Right-of-use assets	9,438,000	5,114,000
Lease liability, less current portion	$ 10,814,000	6,719,000
Accounting Standards Update 2016-02 [Member]
Summary Of Significant Accounting Policies [Line Items]
Right-of-use assets				$ 100,000
Lease liability, less current portion				$ 100,000
Acquired Patents And Licenses [Member]
Summary Of Significant Accounting Policies [Line Items]
Intangible asset useful life	12 years
Maximum [Member] | Equipment [Member]
Summary Of Significant Accounting Policies [Line Items]
Useful life	5 years
Minimum [Member] | Equipment [Member]
Summary Of Significant Accounting Policies [Line Items]
Useful life	3 years
Accumulated Deficit [Member]
Summary Of Significant Accounting Policies [Line Items]
Stockholders Equity	$ (172,540,000)	$ (122,689,000)	$ (75,718,000)		$ (38,173,000)

Summary Of Significant Accoun_5

Summary Of Significant Accounting Policies (Anti-Dilutive Shares Excluded From Computation Of Diluted Net Loss Per Share) (Details) - shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total	5,762,809	4,139,639	3,392,778
Warrants [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total	612,310	167,847	213,485
Employee Stock Option [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total	5,039,194	3,749,186	2,956,687
Restricted Stock Units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total	111,305	222,606	222,606

Fair Value Of Financial Instrum

Fair Value Of Financial Instruments (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
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 Of_3

Investments And Fair Value Of Financial Instruments (Schedule Of Available-For-Sale Securities) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Schedule Of Available For Sale Securities [Line Items]
Cost	$ 8,013	$ 18,495
Gross Unrealized Gains		4
Fair Value	8,012	18,499
US Treasury Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Cost	8,013	18,495
Gross Unrealized Gains		4
Gross Unrealized Losses	(1)
Fair Value	$ 8,012	$ 18,499

Investments And Fair Value Of_4

Investments And Fair Value Of Financial Instruments (Schedule Of Contractual Maturities) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Investments And Fair Value Of Financial Instruments [Abstract]
Due in one year	$ 8,012	$ 18,499
Total	$ 8,012	$ 18,499

Investments And Fair Value Of_5

Investments And Fair Value Of Financial Instruments (Fair Value Of Financial Assets Measured On A Recurring Basis) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
ASSETS
Total assets measured at fair value	$ 17,192	$ 24,928
Cash And Cash Equivalents [Member] | Money Market Funds [Member]
ASSETS
Total cash and cash equivalents	7,176	6,429
Cash And Cash Equivalents [Member] | U.S. Treasury Securities [Member]
ASSETS
Total cash and cash equivalents	2,004
Investments [Member] | U.S. Treasury Securities [Member]
ASSETS
Total investments	8,012	18,499
Level 1 [Member]
ASSETS
Total assets measured at fair value	7,176	6,429
Level 1 [Member] | Cash And Cash Equivalents [Member] | Money Market Funds [Member]
ASSETS
Total cash and cash equivalents	7,176	6,429
Level 2 [Member]
ASSETS
Total assets measured at fair value	10,016	18,499
Level 2 [Member] | Cash And Cash Equivalents [Member] | U.S. Treasury Securities [Member]
ASSETS
Total cash and cash equivalents	2,004
Level 2 [Member] | Investments [Member] | U.S. Treasury Securities [Member]
ASSETS
Total investments	$ 8,012	$ 18,499

Balance Sheet Components (Narra

Balance Sheet Components (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Jul. 31, 2017
Balance Sheet Components [Line Items]
Improvement allowance, capitalized				$ 2,100
Depreciation expense	$ 430	$ 494	$ 645
Intangible asset useful life	12 years
Compensation expense	$ 3,324	1,699
Executive Officer [Member]
Balance Sheet Components [Line Items]
Compensation expense		$ 300

Balance Sheet Components (Sched

Balance Sheet Components (Schedule Of Property And Equipment, Net) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Equipment, gross	$ 4,394	$ 4,052
Less: Accumulated depreciation and amortization	(1,916)	(1,486)
Equipment, net	2,478	2,566
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Equipment, gross	2,805	2,248
Laboratory Equipment [Member]
Property, Plant and Equipment [Line Items]
Equipment, gross	878	677
Furniture, Fixtures, And Equipment [Member]
Property, Plant and Equipment [Line Items]
Equipment, gross	517	466
Software [Member]
Property, Plant and Equipment [Line Items]
Equipment, gross	128	118
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Equipment, gross	$ 66	$ 543

Balance Sheet Components (Sch_2

Balance Sheet Components (Schedule Of Intangible Assets, Net) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Balance Sheet Components [Abstract]
Acquired patents and licenses	$ 7,985	$ 7,985
Less: Accumulated amortization	(4,103)	(3,438)
Intangible assets, net	$ 3,882	$ 4,547

Balance Sheet Components (Sch_3

Balance Sheet Components (Schedule Of Amortization Of Intangible Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Balance Sheet Components [Abstract]
2021	$ 665
2022	665
2023	665
2024	665
2025	665
Thereafter	557
Intangible assets, net	$ 3,882	$ 4,547

Balance Sheet Components (Sch_4

Balance Sheet Components (Schedule Of Accrued Expenses) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Balance Sheet Components [Abstract]
Compensation expense	$ 3,324	$ 1,699
Director and officer liability insurance (Note 9)	1,563
Accrued clinical	188	262
Professional fees	87	51
Property and equipment		234
Other	164	250
Accrued expenses	$ 5,326	$ 2,496

Goodwill (Narrative) (Details)

Goodwill (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2014	Dec. 31, 2019
Business Acquisition, Equity Interests Issued or Issuable [Line Items]
Goodwill	$ 2,791,000		$ 2,791,000
Goodwill impairment	$ 0
TPI, BEM And NB [Member]
Business Acquisition, Equity Interests Issued or Issuable [Line Items]
Aggregate consideration		$ 5,500,000
Goodwill		$ 2,800,000

Stockholders' Equity And Stoc_3

Stockholders' Equity And Stock-Based Compensation (Narrative) (Details) - USD ($)

Feb. 05, 2021

Feb. 04, 2021

Jan. 01, 2020

Jan. 01, 2019

Dec. 06, 2018

Jun. 30, 2020

Dec. 31, 2020

Dec. 31, 2019

Dec. 31, 2018

Dec. 31, 2014

Feb. 28, 2021

Oct. 25, 2018

Nov. 30, 2017

Stockholders' Equity [Line Items]

Common stock, par value

$ 0.001

$ 0.001

Common stock, shares issued

25,550,000

20,825,000

Options granted

1,973,810

Warrants exercised

175,066

Exercise price

$ 17.03

Total intrinsic value of options exercised

$ 1,600,000

$ 1,000,000

$ 1,800,000

Fair value of options vested

6,700,000

8,400,000

6,400,000

Total stock-based compensation expense

10,075,000

$ 11,287,000

12,338,000

Unrecognized compensation cost

$ 9,600,000

Weighted average remaining contractual life

2 years 6 months

2017 Employee Stock Purchase Plan [Member]

Stockholders' Equity [Line Items]

Common stock, shares issued

82,971

38,279

Shares authorized

250,000

Increase in shares available for issuance threshold of common stock outstanding, number of shares

450,000

Increase in shares available for issuance threshold of common stock outstanding, percent outstanding

1.50%

Shares available for grant

357,224

2017 Inducement Equity Incentive Plan [Member]

Stockholders' Equity [Line Items]

Term period

10 years

10 years

Shares authorized

1,000,000

2017 Plan [Member]

Stockholders' Equity [Line Items]

Term period

10 years

Shares authorized

1,500,000

Additional common stock reserved for issuance

833,018

823,716

Increase in shares available for issuance threshold of common stock outstanding, number of shares

1,200,000

Increase in shares available for issuance threshold of common stock outstanding, percent outstanding

4.00%

Shares available for grant

465,899

Rights Offering [Member]

Stockholders' Equity [Line Items]

Common stock, par value

$ 0.001

Value of warrants/rights

$ 30,000,000

Number of warrants to purchase shares of common stock

0.15

Net proceeds

$ 29,400,000

Warrants/rights outstanding

641,571

480,687

Exercise price of warrants/rights

$ 7.01

Redemption per warrant

$ 0.01

Period the warrants are exercisable after issuance

30 days

Percentage requirement for warrant redemption

200.00%

Period of time required for redemption of warrants

10 days

Period of time warrant not able to be redeemed

6 months

Number of common shares called by issuance of warrants

4,279,600

First Vesting Portion [Member] | 2017 Inducement Equity Incentive Plan [Member]

Stockholders' Equity [Line Items]

Vesting percentage

25.00%

New Hires [Member] | 2017 Inducement Equity Incentive Plan [Member]

Stockholders' Equity [Line Items]

Vesting period

4 years

General and administrative [Member]

Stockholders' Equity [Line Items]

Total stock-based compensation expense

$ 6,062,000

$ 7,466,000

9,004,000

Research and development [Member]

Stockholders' Equity [Line Items]

Total stock-based compensation expense

4,013,000

$ 3,821,000

3,334,000

Restricted Stock Units [Member]

Stockholders' Equity [Line Items]

Units granted during period

0

Reduction to APIC from shares withheld for tax

$ 100,000

Total stock-based compensation expense

$ 0

$ 0

$ 2,100,000

Warrants [Member]

Stockholders' Equity [Line Items]

Options granted

641,571

Warrants exercised

197,108

Aggregate intrinsic value exercisable options

$ 10,700,000

Subsequent Event [Member]

Stockholders' Equity [Line Items]

Value of warrants/rights

$ 60,000,000

Subsequent Event [Member] | Rights Offering [Member]

Stockholders' Equity [Line Items]

Net proceeds

$ 4,200,000

$ 4,500,000

Redemption per warrant

$ 0.01

Warrants exercised

5,139

636,432

Initial Public Offering [Member] | Warrants [Member]

Stockholders' Equity [Line Items]

Warrants exercised

36,224

Chairman, Robert W. Duggan [Member] | Rights Offering [Member]

Stockholders' Equity [Line Items]

Common stock, par value

$ 0.001

Number of warrants to purchase shares of common stock

2,561,873

Ownership percentage

43.00%

47.00%

43.00%

Shares purchased

2,561,873

Number of common shares called by issuance of warrants

3,146,226

Officer [Member] | Restricted Stock Units [Member]

Stockholders' Equity [Line Items]

Shares available for grant

160,974

Unrecognized compensation cost

$ 0

Certain Employees [Member] | Restricted Stock Units [Member]

Stockholders' Equity [Line Items]

Shares available for grant

68,800

Total stock-based compensation expense

300,000

$ 400,000

$ 400,000

Unrecognized compensation cost

$ 100,000

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

Stockholders' Equity [Line Items]

Warrants exercised

175,000

99,000

145,000

Number of common shares called by issuance of warrants

26,063

Common Stock | 2017 Inducement Equity Incentive Plan [Member]

Stockholders' Equity [Line Items]

Shares authorized

11,158

Common Stock | Rights Offering [Member]

Stockholders' Equity [Line Items]

Net proceeds

$ 44,800,000

Right entitlement to holder

3,581,148

0.19860755

Exercise price of warrants/rights

$ 12.57

$ 12.57

Common Stock | Warrants [Member]

Stockholders' Equity [Line Items]

Warrants exercised

37,000

24,000

Common Stock | Chairman, Robert W. Duggan [Member] | Rights Offering [Member]

Stockholders' Equity [Line Items]

Ownership percentage

35.00%

43.00%

Shares purchased

3,146,226

Investment

$ 39,500,000

MDB Capital Group, LLC [Member] | Initial Public Offering [Member]

Stockholders' Equity [Line Items]

Price per share

$ 5

Warrants/rights outstanding

85,385

Exercisable period of warrants or rights

5 years

Number of common shares called by issuance of warrants

574,985

MDB Capital Group, LLC [Member] | Private Placement [Member]

Stockholders' Equity [Line Items]

Price per share

$ 2.67

Warrants/rights outstanding

46,238

Exercisable period of warrants or rights

7 years

Number of common shares called by issuance of warrants

299,625

Stockholders' Equity And Stoc_4

Stockholders' Equity And Stock-Based Compensation (Summary Of Stock Warrant Activity) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Beginning Balance, Number of shares	3,749,186
Options granted, Number of shares	1,973,810
Options exercised, Number of shares	(175,066)
Options canceled, Number of shares	(351,234)
Options expired, Number of shares	(157,502)
Ending Balance, Number of shares	5,039,194	3,749,186
Beginning Balance, Weighted average exercise price per share	$ 16.18
Options granted, Weighted average exercise price per share	10.19
Options exercised, Weighted average exercise price per share	5.07
Options expired, Weighted average exercise price per share	23.64
Ending Balance, Weighted average exercise price per share	$ 14.26	$ 16.18
Weighted average remaining life	7 years 9 months 29 days	7 years 10 months 24 days
Warrants [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Beginning Balance, Number of shares	167,847
Options granted, Number of shares	641,571
Options exercised, Number of shares	(197,108)
Options expired, Number of shares
Ending Balance, Number of shares	612,310	167,847
Beginning Balance, Weighted average exercise price per share	$ 4.36
Options granted, Weighted average exercise price per share	7.01
Options exercised, Weighted average exercise price per share	6.64
Options expired, Weighted average exercise price per share
Ending Balance, Weighted average exercise price per share	$ 6.40	$ 4.36
Weighted average remaining life	3 months 3 days	1 year 3 months 10 days

Stockholders' Equity And Stoc_5

Stockholders' Equity And Stock-Based Compensation (Summary Of Stock Option Activity) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Stockholders' Equity And Stock-Based Compensation [Abstract]
Beginning Balance, Number of shares	3,749,186
Options granted, Number of shares	1,973,810
Options exercised, Number of shares	(175,066)
Options canceled, Number of shares	(351,234)
Options expired, Number of shares	(157,502)
Ending Balance, Number of shares	5,039,194	3,749,186
Exercisable, Number of shares	2,552,230
Beginning Balance, Weighted average exercise price per share	$ 16.18
Options granted, Weighted average exercise price per share	10.19
Options exercised, Weighted average exercise price per share	5.07
Options canceled, Weighted average exercise price per share	12.71
Options expired, Weighted average exercise price per share	23.64
Ending Balance, Weighted average exercise price per share	14.26	$ 16.18
Exercisable, Weighted average exercise price per share	$ 17.03
Weighted average remaining life	7 years 9 months 29 days	7 years 10 months 24 days
Weighted average remaining life, exercisable	6 years 7 months 6 days

Stockholders' Equity And Stoc_6

Stockholders' Equity And Stock-Based Compensation (Summary Of Exercise Price Of Stock Options Outstanding And Exercisable) (Details) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Stockholders' Equity And Stock-Based Compensation [Abstract]
Weighted average remaining contractual life (in years)	7 years 9 months 29 days	7 years 10 months 24 days
Weighted average exercise price	$ 17.03

Stockholders' Equity And Stoc_7

Stockholders' Equity And Stock-Based Compensation (Schedule Of Fair Value Of Employee Stock Options) (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Employee Stock Option [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected volatility	70.00%
Employee Stock Option [Member] | Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term in years	5 years 3 months 18 days	4 months 24 days	5 years 3 months 18 days
Expected volatility		70.00%	70.00%
Risk-free interest rate	0.30%	1.40%	2.60%
Employee Stock Option [Member] | Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term in years	6 years 1 month 6 days	6 years 1 month 6 days
Risk-free interest rate	0.50%	2.60%	3.00%
2017 Employee Stock Purchase Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected volatility	70.00%	70.00%	70.00%
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	6 months	6 months
Risk-free interest rate	0.10%	1.70%	1.90%
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	1 year	1 year
Risk-free interest rate	1.00%	2.60%	2.50%

Stockholders' Equity And Stoc_8

Stockholders' Equity And Stock-Based Compensation (Summary Of Stock-Based Compensation Expense) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Total stock-based compensation expense	$ 10,075	$ 11,287	$ 12,338
General and administrative [Member]
Total stock-based compensation expense	6,062	7,466	9,004
Research and development [Member]
Total stock-based compensation expense	$ 4,013	$ 3,821	$ 3,334

Research Grants And Agreements

Research Grants And Agreements (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and development expense	$ 26,444	$ 24,961	$ 17,253
Sponsored Research Agreement ("SRA") [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and development expense	$ 600	$ 900	$ 700
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 expense	$ 800

Income Taxes (Narrative) (Detai

Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Taxes [Line Items]
Loss from operations, before income taxes	$ (49,851)	$ (46,971)	$ (37,545)
Income tax provision (benefit)
Federal statutory tax rate	21.00%	21.00%	21.00%
Increase in valuation allowance	$ 21,600	$ 7,700
Total unrecognized tax benefit	$ 2,491	1,470	$ 877	$ 512
Federal And California [Member]
Income Taxes [Line Items]
Net operating loss carryforwards		$ 99,000
Net operating loss carryforward, expiration	2034
NOL, percent of taxable income	80.00%
Federal [Member]
Income Taxes [Line Items]
Net operating loss carryforwards	$ 125,000
Research and development credit carryforward	$ 4,200
Research and developmen tax credit carryforward, expiration	2035
California [Member]
Income Taxes [Line Items]
Net operating loss carryforwards	$ 117,000
Research and development credit carryforward	$ 3,800

Income Taxes (Income (Loss) Bef

Income Taxes (Income (Loss) Before Income Taxes) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Taxes [Abstract]
Domestic	$ (49,851)	$ (46,971)	$ (37,545)
Income (loss) before income taxes	$ (49,851)	$ (46,971)	$ (37,545)

Income Taxes (Components of Inc

Income Taxes (Components of Income Tax Expense (Benefit)) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current
State	$ 3	$ 3	$ 3
Total current	3	3	3
Total provision for income taxes	$ 3	$ 3	$ 3

Income Taxes (Reconcilement Of

Income Taxes (Reconcilement Of Tax Rates) (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Taxes [Abstract]
Federal tax (benefit) at statutory rate	21.00%	21.00%	21.00%
State tax (benefit) at statutory rate	8.40%	(5.00%)	7.00%
Research and development credits	2.10%	2.00%	(2.00%)
Change in valuation allowance	(43.30%)	(18.00%)	(28.00%)
Deferred adjustment	8.50%
Change in tax rate	4.20%
Tax reform			2
Other	(0.80%)

Income Taxes (Components Of Def

Income Taxes (Components Of Deferred Tax Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Income Taxes [Abstract]
Accruals	$ 894	$ 119
Net operating loss carryforwards	36,531	20,755
Tax credit carryforwards	5,431	4,409
Stock-based compensation	9,391	5,473
Lease liability under ASC 842	3,339	1,411
Gross deferred tax assets	55,586	32,167
Valuation allowance	(51,973)	(30,369)
Total deferred tax assets	3,613	1,798
Intangibles	(486)	(434)
ROU asset under ASC 842	(3,096)	(1,364)
Fixed assets	(31)
Total deferred tax liability	$ (3,613)	$ (1,798)

Income Taxes (Reconciliation Of

Income Taxes (Reconciliation Of Unrecognized Tax Benefit Accounts) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Taxes [Abstract]
Unrecognized tax benefits, Beginning balance	$ 1,470	$ 877	$ 512
Increases related to current year tax positions	1,021	593	365
Unrecognized tax benefits, Ending balance	$ 2,491	$ 1,470	$ 877

Related Party Transactions (Nar

Related Party Transactions (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions	Feb. 05, 2021	Feb. 04, 2021	Dec. 06, 2018	Jun. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Mar. 09, 2021	Feb. 28, 2021	Oct. 25, 2018
Related Party Transaction [Line Items]
Fees and Commissions, Executive Search					$ 0.5	$ 0.6	$ 0.6
Common stock, shares issued					25,550,000	20,825,000
Common stock, par value					$ 0.001	$ 0.001
Coverage period					1 year
Deposit for insurance					$ 30
Chairman, Robert W. Duggan [Member] | Rights Offering [Member]
Related Party Transaction [Line Items]
Common stock, par value							$ 0.001
Number of warrants to purchase shares of common stock				2,561,873
Number of common shares called by issuance of warrants							3,146,226
Ownership percentage				43.00%	47.00%	43.00%
MDB Capital Group, LLC [Member] | Initial Public Offering [Member]
Related Party Transaction [Line Items]
Warrants/rights outstanding					85,385
Number of common shares called by issuance of warrants							574,985
Robert W. Duggan [Member]
Related Party Transaction [Line Items]
Due to related parties					$ 2.5
Wilson Sonsini Goodrich And Rosati (WSGR) [Member]
Related Party Transaction [Line Items]
Related party expenses					0.8	$ 0.5	$ 1.2
Wilson Sonsini Goodrich And Rosati (WSGR) [Member] | Rights Offering [Member]
Related Party Transaction [Line Items]
Related party expenses						$ 0.1
Legal Expenses [Member] | Wilson Sonsini Goodrich And Rosati (WSGR) [Member] | Rights Offering [Member]
Related Party Transaction [Line Items]
Related party expenses					0.4
Letter Agreement [Member] | Robert W. Duggan [Member]
Related Party Transaction [Line Items]
Due to related parties					$ 1.6
Common Stock
Related Party Transaction [Line Items]
Number of common shares called by issuance of warrants					26,063
Common Stock | Chairman, Robert W. Duggan [Member] | Rights Offering [Member]
Related Party Transaction [Line Items]
Ownership percentage			35.00%				43.00%
Subsequent Event [Member]
Related Party Transaction [Line Items]
Value of warrants/rights									$ 60
Subsequent Event [Member] | Robert W. Duggan [Member]
Related Party Transaction [Line Items]
Due to related parties								$ 41
Rights Offering [Member]
Related Party Transaction [Line Items]
Common stock, par value				$ 0.001
Warrants/rights outstanding				641,571	480,687
Number of warrants to purchase shares of common stock				0.15
Exercise price of warrants/rights				$ 7.01
Number of common shares called by issuance of warrants				4,279,600
Value of warrants/rights				$ 30
Net proceeds				$ 29.4
Rights Offering [Member] | Common Stock
Related Party Transaction [Line Items]
Exercise price of warrants/rights			$ 12.57							$ 12.57
Net proceeds			$ 44.8
Rights Offering [Member] | Subsequent Event [Member]
Related Party Transaction [Line Items]
Net proceeds	$ 4.2	$ 4.5

Commitments And Contingencies_2

Commitments And Contingencies (Narrative) (Details) $ in Millions	1 Months Ended			12 Months Ended
	May 31, 2020USD ($)	Nov. 30, 2019USD ($)	Jan. 31, 2019USD ($)	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	May 31, 2019ft²	Jan. 31, 2017ft²
Commitments and Contingencies [Line Items]
Lease term								5 years
Area Of Lease | ft²								15,700
Rent expense, including common area maintenance charges | $				$ 1.7	$ 0.5	$ 0.2
Lease Amendment - Phase One [Member]
Commitments and Contingencies [Line Items]
Area Of Lease | ft²							13,300
Lease Amendment - Phase Two [Member]
Commitments and Contingencies [Line Items]
Area Of Lease | ft²							21,300
Accounting Standards Update 2016-02 [Member]
Commitments and Contingencies [Line Items]
Increase in right-of-use assets | $	$ 4.8	$ 3	$ 2	9.4
Increase in lease liability | $				$ 11.4

Commitments And Contingencies_3

Commitments And Contingencies (Schedule Of Maturity Lease Payments) (Details) $ in Thousands	Dec. 31, 2020USD ($)
Commitments And Contingencies [Abstract]
2021	$ 1,643
2022	1,806
2023	1,845
2024	1,910
Thereafter	10,214
Total lease payments	17,418
Less imputed interest	(6,062)
Total lease liabilities	$ 11,356

Commitments And Contingencies_4

Commitments And Contingencies (Schedule Of Information Related To Right-Of-Use Assets And Lease Liabilities) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Commitments And Contingencies [Abstract]
Cash paid for operating lease liabilities	$ 1,045
Operating lease liabilities arising from ROU assets	4,833
Current operating lease liabilities	542
Non-current operating lease liabilities	10,814	$ 6,719
Total lease liabilities	$ 11,356
Weighted average remaining lease term	8 years 9 months 29 days
Weighted average discount rate	10.00%

Employee Benefit Plans (Narrati

Employee Benefit Plans (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Employee Benefit Plans [Abstract]
Employer matching contributions	$ 0	$ 0	$ 0

Subsequent Events (Narrative) (

Subsequent Events (Narrative) (Details) - USD ($) $ in Millions	Mar. 11, 2021	Mar. 09, 2021	Feb. 28, 2021	Dec. 31, 2020
Subsequent Event [Member]
Subsequent Event [Line Items]
Value of warrants/rights			$ 60
Robert W. Duggan [Member]
Subsequent Event [Line Items]
Due to related parties				$ 2.5
Robert W. Duggan [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Due to related parties		$ 41
Debt instrument, stated interest rate		5.00%
Debt instrument, interest rate upon default	7.00%
Debt instrument, late payment fee, percent	2.00%