0001069530-21-000020 | 10-K | XBRL Viewer

Document And Entity Information - USD ($)	12 Months Ended
Document And Entity Information - USD ($)	Dec. 31, 2020	Mar. 18, 2021	Jun. 30, 2020
Document And Entity Information [Abstract]
Document Type	10-K
Document Annual Report	true
Document Fiscal Period Focus	FY
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Period End Date	Dec. 31, 2020
Document Transition Report	false
Entity File Number	000-29959
Entity Registrant Name	CASSAVA SCIENCES INC
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	91-1911336
Entity Address, Address Line One	7801 N. Capital of Texas Highway
Entity Address, Address Line Two	Suite 260
Entity Address, City or Town	Austin
Entity Address, State or Province	TX
Entity Address, Postal Zip Code	78731
City Area Code	512
Local Phone Number	501-2444
Title of 12(b) Security	Common Stock, $0.001 par value
Trading Symbol	sava
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	Yes
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	false
ICFR Auditor Attestation Flag	false
Entity Shell Company	false
Entity Public Float			$ 71,146,906
Entity Common Stock, Shares Outstanding		39,898,325
Documents Incorporated by Reference	Portions of the Registrant's Proxy Statement for its 2021 Annual Meeting of Stockholders (the Proxy Statement), to be filed with the U.S. Securities and Exchange Commission, are incorporated by reference to Part III of this Form 10-K Report.
Amendment Flag	false
Entity Central Index Key	0001069530

Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 93,506	$ 23,081
Other current assets	488	268
Total current assets	93,994	23,349
Operating lease right-of-use assets	295	90
Property and equipment, net	11	47
Total assets	94,300	23,486
Current liabilities:
Accounts payable	911	453
Accrued development expense	719	777
Accrued compensation and benefits	83	58
Operating lease liabilities, current	58	90
Other current liabilities	94	9
Total current liabilities	1,865	1,387
Operating lease liabilities, non-current	235
Total liabilities	2,100	1,387
Commitments and contingencies (Note 7 and 8)
Stockholders' equity:
Preferred stock, $.001 par value; 10,000,000 shares authorized, none issued and outstanding
Common stock, $.001 par value; 120,000,000 shares authorized; 35,237,987 and 21,841,810 shares issued and outstanding at December 31, 2020 and 2019, respectively	35	22
Additional paid-in capital	267,086	190,664
Accumulated deficit	(174,921)	(168,587)
Total stockholders' equity	92,200	22,099
Total liabilities and stockholders' equity	$ 94,300	$ 23,486

Statements Of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Operating expenses:
Research and development, net of grant reimbursement	$ 3,053	$ 1,568
General and administrative	3,739	3,391
Gain on sale of property and equipment	(346)
Total operating expenses	6,446	4,959
Operating loss	(6,446)	(4,959)
Interest income	112	328
Net loss	$ (6,334)	$ (4,631)
Net loss per share, basic and diluted	$ (0.24)	$ (0.27)
Shares used in computing net loss per share, basic and diluted	26,105	17,412

Statements Of Stockholders' Equity - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Deficit [Member]	Total
Balance at Dec. 31, 2018	$ 17	$ 183,567	$ (163,956)	$ 19,628
Balance, Shares at Dec. 31, 2018	17,219,300
Stock options for employees		1,287		1,287
Stock options for non-employees		9		9
Issuance costs from 2018 sale of common stock and warrants		(60)		(60)
Issuance of common stock pursuant to exercise of warrants	$ 5	5,861		5,866
Issuance of common stock pursuant to exercise of warrants, shares	4,622,510
Net loss			(4,631)	(4,631)
Balance at Dec. 31, 2019	$ 22	190,664	(168,587)	22,099
Balance, Shares at Dec. 31, 2019	21,841,810
Stock options for employees		961		961
Stock options for non-employees		27		27
Issuance of common stock pursuant to exercise of stock options		256		$ 256
Issuance of common stock pursuant to exercise of stock options, shares	71,105			71,105
Issuance of common stock pursuant to exercise of warrants	$ 4	4,936		$ 4,940
Issuance of common stock pursuant to exercise of warrants, shares	3,950,072
Common stock issued in conjunction with follow-on public offering, net of issuance costs	$ 9	70,242		70,251
Common stock issued in conjunction with follow-on public offering, net of issuance costs, shares	9,375,000
Net loss			(6,334)	(6,334)
Balance at Dec. 31, 2020	$ 35	$ 267,086	$ (174,921)	$ 92,200
Balance, Shares at Dec. 31, 2020	35,237,987

Statements Of Cash Flows - USD ($) $ in Thousands	12 Months Ended
Statements Of Cash Flows - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Cash flows from operating activities:
Net loss	$ (6,334)	$ (4,631)
Adjustments to reconcile net loss to net cash used in operating activities:
Non-cash stock-based compensation	988	1,296
Depreciation and amortization	22	58
Gain on sale of property and equipment	(346)
Changes in operating assets and liabilities:
Other current assets	(220)	(23)
Operating lease right-of-use assets and liabilities	(2)
Accounts payable	458	159
Accrued development expense	(58)	621
Accrued compensation and benefits	25	(3)
Other current liabilities	85	9
Net cash used in operating activities	(5,382)	(2,514)
Cash flows from investing activities:
Purchases of property and equipment		(18)
Proceeds from sale of property and equipment	360
Net cash provided by (used in) investing activities	360	(18)
Cash flows from financing activities:
Issuance costs from 2018 sale of common stock and warrants		(60)
Proceeds from exercise of stock options	256
Proceeds from exercise of common stock warrants	4,940	5,866
Proceeds from follow-on public offering, net of issuance costs	70,251
Net cash provided by financing activities	75,447	5,806
Net increase in cash and cash equivalents	70,425	3,274
Cash and cash equivalents at beginning of period	23,081	19,807
Cash and cash equivalents at end of period	$ 93,506	$ 23,081

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

Use of Estimates

The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires that management make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amount of revenue earned and expenses incurred during the reporting period. Actual results could differ from those estimates.

Proceeds from Grants

In 2020, the Company received $4.2 million of reimbursement from the National Institutes of Health and National Institute on Drug Abuse and $4.7 million in 2019. The Company records the proceeds from these grants as reductions to its research and development expenses.

Cash and Cash Equivalents and Concentration of Credit Risk

The Company invests in cash and cash equivalents and, in the past, marketable securities. The Company considers highly-liquid financial instruments with original maturities of three months or less to be cash equivalents. Highly liquid investments that are considered cash equivalents include money market accounts, money market funds and certificates of deposit. The carrying value of cash equivalents approximates fair value due to the short-term maturity of these securities.

The Company’s investment policy allows for investments in marketable securities with active secondary or resale markets, establishes diversification and credit quality requirements and limits investments by maturity and issuer. The Company maintains its investments at one financial institution.

Fair Value Measurements

The Company reports its cash and cash equivalents at fair value as Level 1, Level 2 or Level 3 using the following inputs:

Level 1 includes quoted prices in active markets. The Company bases the fair value of money market funds on Level 1 inputs.

Level 2 includes significant observable inputs, such as quoted prices for identical or similar investments, or other inputs that are observable and can be corroborated by observable market data for similar securities. The Company uses market pricing and other observable market inputs obtained from third-party providers. It uses the bid price to establish fair value where a bid price is available. The Company bases the fair value of its certificates of deposit, if any, on Level 2 inputs.

Level 3 includes unobservable inputs that are supported by little or no market activity. The Company does not have any investments where the fair value is based on Level 3 inputs.

If a financial instrument uses inputs that fall in different levels of the hierarchy, the instrument will be categorized based upon the lowest level of input that is significant to the fair value calculation. A certificate of deposit totaling $13.0 million at December 31, 2019 was included within cash equivalents as a Level 2 input. The fair value of the remainder of cash and cash equivalents, including money market accounts, was based on Level 1 inputs at December 31, 2020 and 2019.

Business Segments

The Company reports segment information based on how it internally evaluates the operating performance of its business units, or segments. The Company’s operations are confined to one business segment: the development of novel drugs and diagnostics.

Stock-based Compensation

The Company recognizes non-cash expense for the fair value of all stock options and other share-based awards. The Company uses the Black-Scholes option valuation model to calculate the fair value of stock options, using the single-option award approach and straight-line attribution method. This model requires the input of subjective assumptions including expected stock price volatility, expected life and estimated forfeitures of each award. These assumptions consist of estimates of future market conditions, which are inherently uncertain, and therefore, are subject to management's judgment. The Company recognizes the resulting fair value as expense on a straight-line basis over the vesting period of each respective stock option, generally four years.

The Company has granted share-based awards that vest upon achievement of certain performance criteria, or performance awards. The Company multiplies the number of performance awards by the fair value of its common stock on the date of grant to calculate the fair value of each award. It estimates an implicit service period for achieving performance criteria for each award. The Company recognizes the resulting fair value as expense over the implicit service period when it concludes that achieving the performance criteria is probable. The Company periodically reviews and updates as appropriate its estimates of implicit service periods and conclusions on achieving the performance criteria. Performance awards vest and common stock is issued upon achievement of the performance criteria.

Net Loss per Share

Basic net loss per share is computed on the basis of the weighted-average number of common shares outstanding for the reporting period. Diluted net loss per share is computed on the basis of the weighted-average number of common shares outstanding plus dilutive potential common shares outstanding using the treasury-stock method. Potential dilutive common shares consist of outstanding equity awards and warrants. There is no difference between the Company’s net loss and comprehensive loss. The numerators and denominators in the calculation of basic and diluted net loss per share were as follows (in thousands, except net loss per share data):




	Year ended December 31,
	2020		2019
Numerator:
Net loss	$	(6,334)	$	(4,631)
Denominator:
Shares used in computing net loss per share, basic and diluted		26,105		17,412
Net loss per share, basic and diluted	$	(0.24)	$	(0.27)

Dilutive common stock options excluded from net loss per share, diluted		2,145		2,932
Common stock warrants excluded from net loss per share, diluted		554		4,504

The Company excluded weighted equity awards and warrants outstanding to purchase common stock from the calculation of diluted net loss per share because the effect of including these shares in this calculation would be anti-dilutive.

Fair Value of Financial Instruments

Financial instruments include cash and cash equivalents, accounts payable and accrued liabilities. The estimated fair value of financial instruments has been determined using available market information or other appropriate valuation methodologies. However, considerable judgment is required in interpreting market data to develop estimates of fair value; therefore, the estimates are not necessarily indicative of the amounts that could be realized or would be paid in a current market exchange. The effect of using different market assumptions and/or estimation methodologies may be material to the estimated fair value amounts. The carrying amounts of cash and cash equivalents, accounts payable and accrued liabilities are at cost, which approximates fair value due to the short maturity of those instruments.

Research Contract Costs and Accruals

The Company has entered into various research and development contracts with research institutions and other third-party vendors. These agreements are generally cancelable, and related payments are recorded as research and development expenses as incurred. The Company records accruals for estimated ongoing research costs. When evaluating the adequacy of the accrued liabilities, the Company analyzes progress of the studies including the phase or completion of events, invoices received and contracted costs. Significant judgments and estimates are made in determining the accrued balances at the end of any reporting period. Actual results could differ from the Company’s estimates. The Company’s historical accrual estimates have not been materially different from actual costs.

Incentive Bonus Plan

In 2020, the Company established the 2020 Cash Incentive Bonus Plan (the “Plan”) to incentivize Plan participants. Awards under the Plan are accounted for as liability awards under ASC 718 “Stock-based Compensation”. The fair value of each potential Plan award will be determined once a grant date occurs and will be remeasured each reporting period. Compensation expense associated with the Plan will be recognized over the expected achievement period for each Plan award, when a Performance Condition is considered probable of being met. See Note 8 for further discussion of the Plan.

Leases

The Company recognizes assets and liabilities that arise from leases. For operating leases, the Company is required to recognize a right-of-use asset and a lease liability, initially measured at the present value of the lease payments, in the statements of financial position. As the Company`s leases do not provide an implicit rate, it uses its incremental borrowing rate based on the information available at the commencement date in determining the present value of lease payments. Lease expense for lease payments is recognized on a straight-line basis over the lease term.

Income Taxes

The Company accounts for income taxes under the asset and liability method. Deferred tax assets and liabilities are recognized for the estimated future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. Deferred tax balances are adjusted to reflect tax rates based on currently enacted tax laws, which will be in effect in the years in which the temporary differences are expected to reverse. The Company has accumulated significant deferred tax assets that reflect the tax effects of net operating loss and tax credit carryovers and temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. Realization of certain deferred tax assets is dependent upon future earnings. The Company is uncertain about the timing and amount of any future earnings. Accordingly, the Company offsets these deferred tax assets with a valuation allowance.

The Company accounts for uncertain tax positions in accordance with ASC 740, “Income Taxes”, which clarifies the accounting for uncertainty in tax positions. These provisions require recognition of the impact of a tax position in the Company’s financial statements only if that position is more likely than not of being sustained upon examination by taxing authorities, based on the technical merits of the position. Any interest and penalties related to uncertain tax positions will be reflected as a component of income tax expense.

Recent Accounting Pronouncements

The Company reviewed recently issued accounting pronouncements and plan to adopt those that are applicable to it, and does not expect the adoption of these pronouncements to have a material impact on its financial position, results of operations or cash flows.

In December 2019, the FABS issued ASU No. 2019-12, Income Taxes (Topic 740) Simplifying Accounting for Income Taxes as part of its initiative to reduce complexity in the accounting standards. The guidance amended certain disclosure requirements that had become redundant, outdated or superseded. Additionally, this guidance amends accounting for the interim period effects of changes in tax laws or rates and simplifies aspects of the accounting for franchise taxes. The guidance is effective for annual periods beginning after December 15, 2020, and is applicable for the Company in fiscal year 2021. Early adoption is permitted. The Company does not anticipate that this guidance will have a material impact on its consolidated financial statements.

In November 2018, the FASB issued ASU No. 2018-18, Collaborative Arrangements (Topic 808): Clarifying the Interaction Between Topic 808 and Topic 606. The amendments in this update provide guidance on how to assess whether certain transactions between collaborative arrangement participants should be accounted for within the revenue recognition standard. The amendments in this update are effective for interim and annual periods for the Company beginning on January 1, 2020. The adoption of this guidance did not have a material impact on the Company’s financial statements.

In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820) - Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement (ASU 2018-13), which is designed to improve the effectiveness of disclosures by removing, modifying and adding disclosures related to fair value measurements. ASU 2018-13 is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. The adoption of ASU 2018-13 did not have a material impact on the Company’s financial statements.

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

4. Stockholders' Equity and Stock-Based Compensation

Preferred Stock

The Company’s Board of Directors (the “Board”) has the authority to issue preferred stock in one or more series and to fix the rights, preferences, privileges, restrictions and the number of shares constituting any series or the designation of the series.

2021 Registered Direct Offering

On February 12, 2021, the Company completed a common stock offering pursuant to which certain investors purchased 4,081,633 shares of common stock at a price of $49.00 per share. Net proceeds of the offering were approximately $189.7 million after deducting offering expenses.

2020 Follow-on Public Offering

On November 13, 2020, the Company completed the sale of 9,375,000 shares of Cassava common stock in an underwritten public offering at a price of $8.00 per share. The Company received net proceeds from the offering of $70,251,000 after deducting underwriting discounts and offering expenses.

Common Stock Warrants

In August 2018, the Company issued warrants to purchase up to an aggregate of 9.1 million shares of its common stock in conjunction with an offering of its common stock.

During 2020, the Company received proceeds of $4.9 million from the exercise of 4.0 million shares pursuant to warrants. During 2019, the Company received proceeds of $5.9 million from the exercise of 4.6 million shares pursuant to warrants.

Subsequent to December 31, 2020, the Company received proceeds of $0.7 million from the exercise of an additional 0.6 million shares pursuant to warrants. There were no warrants outstanding following the 2021 exercises.

Warrants outstanding as of December 31, 2020 and 2019 were as follows:


			Number of Shares Outstanding under Warrant
			December 31,
Issuance Date	Expiration Date	Exercise Price Per Share	2020	2019

August 17, 2018	February 17, 2021	1.25	554,019	4,496,116
August 17, 2018	February 17, 2021	1.59	—	7,975
			554,019	4,504,091

At the Market (ATM) Common Stock Issuance

On March 27, 2020, the Company established an at-the-market offering program (ATM) to sell, from time to time, shares of Company common stock having an aggregate offering price of up to $100 million in transactions pursuant to a shelf registration statement that was declared effective by the U.S. Securities and Exchange Commission (the SEC) on May 5, 2020. The Company is obligated to pay a commission of 3.0% of the gross proceeds from the sale of shares of common stock in the offering. The Company is not obligated to sell any shares in the offering.

There were no common stock sales under the ATM during the year ended December 31, 2020.

2008 Equity Incentive Plan

Under the Company’s 2008 Equity Incentive Plan, or 2008 Equity Plan, its employees, directors and consultants received share-based awards, including grants of stock options and performance awards. The 2008 Equity Plan expired in December 2017. Share-based awards generally expire ten years from the date of grant.

2018 Equity Incentive Plan

In January 2018, the Company’s Board approved the Company’s 2018 Omnibus Incentive Plan (the 2018 Plan). The Company’s Board or a designated Committee of the Board is responsible for administration of the 2018 Plan and determined the terms and conditions of each option granted, consistent with the terms of the 2018 Plan. The Company’s employees, directors, and consultants are eligible to receive awards under the 2018 Plan, including grants of stock options and performance awards. Share-based awards generally expire ten years from the date of grant. The 2018 Plan provides for issuance of up to 1,000,000 shares of common stock, par value $0.001 per share under the 2018 Plan, subject to adjustment as provided in the 2018 Plan.

When stock options or performance awards are exercised net of the exercise price and taxes, the number of shares of stock issued is reduced by the number of shares equal to the amount of taxes owed by the award recipient and that number of shares are cancelled. The Company then uses its cash to pay tax authorities the amount of statutory taxes owed by and on behalf of the award recipient.

Stock Options

The following summarizes information about stock option activity during 2020:


	Number of Options		Weighted Average Exercise Price	Weighted Average Remaining Contractual Term	Aggregate Intrinsic Value
				In years	In millions
Outstanding as of December 31, 2019	3,210,965	$	12.27	6.05	$	4.2
Options granted	60,000		7.25
Options exercised	(71,105)		3.60
Options forfeited/canceled	(382,356)		20.31
Outstanding as of December 31, 2020	2,817,504		11.30	5.60	$	6.4
Vested and expected to vest at December 31, 2020	2,817,504		11.30	5.60	$	6.4
Exercisable at December 31, 2020	2,167,633	$	13.86	4.85	$	3.7

The following summarizes information about stock options at December 31, 2020 by a range of exercise prices:


				Options outstanding				Options exercisable
					Weighted
					average	Weighted			Weighted
				Number of	remaining	average		Number of	average
Range of exercise prices				outstanding	contractual	exercise		vested	exercise
From		To		options	life (in years)	price		options	price
$	0.95	$	1.88	659,688	8.4	$	1.47	251,613	$	1.31
$	3.24	$	4.09	812,094	6.7	$	3.51	643,377	$	3.48
$	4.10	$	13.09	598,462	5.0	$	10.89	525,383	$	11.42
$	14.21	$	35.00	619,599	2.8	$	24.02	619,599	$	24.02
$	36.40	$	53.55	127,661	0.7	$	51.72	127,661	$	51.72
				2,817,504	5.6	$	11.30	2,167,633	$	13.86

The Company uses Black-Scholes to estimate the fair value of options granted. Black-Scholes considers a number of factors, including the market price of the Company’s common stock. It used certain factors to value each stock option granted, which resulted in a weighted average fair value of options granted during 2020 and 2019, as follows:


	2020	2019
Volatility	123% to 139%	118% to 119%
Risk-free interest rates	0.46% to 0.78%	1.7% to 2.5%
Expected life of option	7 years	7 years
Dividend yield	zero	zero
Forfeiture rate	zero	zero
Weighted average fair value of stock options granted	$6.69	$1.60

Volatility is based on reviews of the historical volatility of the Company’s common stock. Risk-free interest rates are based on yields of U.S. treasury notes in effect at the date of grant. Expected life of option is based on actual historical option exercises. Dividend yield is zero because the Company does not anticipate paying cash dividends in the foreseeable future.

As of December 31, 2020, the Company expects to recognize compensation expense of $1.5 million related to non-vested options held by equity plan participants over the weighted average remaining recognition period of 2.1 years.

Subsequent to December 31, 2020, there were 20,385 stock options exercised resulting in proceeds to the Company totaling $169,000.

Performance Awards

The following summarizes information about performance award activity during 2020:


		Number of Performance Awards
Outstanding as of December 31, 2019		138,055
Granted		—
Vested performance awards		—
Forfeited/Canceled		—
Outstanding as of December 31, 2020		138,055

If and when outstanding performance awards vest, the Company would recognize $2.3 million in non-cash stock-based compensation expense. These performance awards expire between 2022 and 2026.

Stock-Based Compensation Expense

The following summarizes information about non-cash stock-based compensation expense, in thousands:



	Year ended
	December 31,
	2020		2019
Research and development	$	453	$	542

General and administrative		535		754

Total non-cash stock-based compensation expense	$	988	$	1,296

Income Taxes

12 Months Ended

Dec. 31, 2020

Income Taxes [Abstract]

Income Taxes

6. Income Taxes

The Company did not provide for income taxes in 2020 and 2019 because it had book and federal taxable losses in those years and the tax benefit that would have resulted from the pre-tax losses was fully offset by a change in the valuation allowance.

The reconciliation of the statutory federal income tax rate to the Company’s effective tax rate for the years ended December 31, 2020 and 2019 was as follows:



	Year ended December 31,
	2020		2019
Tax at federal statutory rate	21.0	%		21.0	%
State tax, net of federal benefit	—			—
Share-based compensation	(42.8)			(2.4)
Research and development credits	1.6			0.6
Change in valuation allowance	20.2			(19.2)
Effective income tax rate	—	%		—	%

Deferred tax assets and valuation allowance

Deferred tax assets reflect the tax effects of net operating loss and tax credit carryforwards and temporary differences between the carrying amounts of assets and liabilities for financial reporting purposes and the amounts used for income tax purposes. The Company’s deferred taxes assets at December 31, 2020 and 2019 were valued at the corporate tax rate of 21%. The Company offsets its deferred tax assets by a valuation allowance because it is uncertain about the timing and amount of any future profits. Significant components of its deferred tax assets are as follows (in thousands):


	December 31,
	2020		2019
Deferred tax assets:
Net operating loss carryforwards	$	18,333	$	17,110
Share-based compensation		3,230		5,817
Research and development credit carryforwards		6,687		6,587
Other		264		237
Total deferred tax assets:		28,514		29,751
Valuation allowance		(28,447)		(29,725)
Net deferred tax assets:		67		26
Deferred tax liabilities:
Property and equipment		(5)		(7)
Operating lease right-of-use assets		(62)		(19)
Total deferred tax liabilities:		(67)		(26)
Net deferred tax asset / (liability):	$	—	$	—

The valuation allowance decreased by $1.3 million in 2020. The valuation allowance decreased by $2.4 million due to a write down of the share-based compensation deferred tax asset and is offset in part by a $1.1 million increase due to additional book losses during the year. The valuation allowance increased by $0.9 million in 2019 due to additional book losses during the year.

The Company’s pre-tax net operating loss carryforwards of $87.3 million are federal, of which $74.1 million expires between 2029 and 2039 and $13.2 million carries forward indefinitely. As of December 31, 2020, the Company had federal research and development tax credits of approximately $11.1 million, which expire in the years 2023 through 2040.

Unrecognized tax benefits

As of December 31, 2020 and 2019, the Company has unrecognized tax benefits related to tax credits of $4.5 million and $4.4 million, respectively. None of the unrecognized tax benefits as of December 31, 2020, if recognized, would impact the effective tax rate due to the valuation allowance and no interest or penalties have been recognized. A reconciliation of the beginning and ending balance of unrecognized tax benefits is as follows (in thousands):



		Year ended December 31,
	2020		2019
Beginning balance	$	4,400	$	4,400
Additions based on tax positions related to the current year		100		—
Ending balance	$	4,500	$	4,400

As of December 31, 2020, there were no unrecognized tax benefits that we expect would change significantly over the next 12 months.

The Company files U.S. and Texas income tax returns. In the United States, the statute of limitations with respect to the federal income tax returns for tax years after 2016 are open to audit; however, since the Company has net operating losses, the taxing authority has the ability to review tax returns prior to the 2017 tax year and make adjustments to these net operating loss carryforwards. We are not under audit in any taxing jurisdiction at this time.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References + Details

Summary Of Significant Accounting Policies (Policy)

12 Months Ended

Dec. 31, 2020

Summary Of Significant Accounting Policies [Abstract]

Use Of Estimates

Use of Estimates

Proceeds From Grants

Proceeds from Grants

Cash And Cash Equivalents And Concentration Of Credit Risk

Cash and Cash Equivalents and Concentration of Credit Risk

Fair Value Measurements

The Company reports its cash and cash equivalents at fair value as Level 1, Level 2 or Level 3 using the following inputs:

Level 1 includes quoted prices in active markets. The Company bases the fair value of money market funds on Level 1 inputs.

Level 3 includes unobservable inputs that are supported by little or no market activity. The Company does not have any investments where the fair value is based on Level 3 inputs.

Business Segments

Stock-Based Compensation

Stock-based Compensation

Net Loss Per Share

Net Loss per Share




	Year ended December 31,
	2020		2019
Numerator:
Net loss	$	(6,334)	$	(4,631)
Denominator:
Shares used in computing net loss per share, basic and diluted		26,105		17,412
Net loss per share, basic and diluted	$	(0.24)	$	(0.27)

Dilutive common stock options excluded from net loss per share, diluted		2,145		2,932
Common stock warrants excluded from net loss per share, diluted		554		4,504

Fair Value Of Financial Instruments

Fair Value of Financial Instruments

Research Contract Costs And Accruals

Research Contract Costs and Accruals

Incentive Bonus Plan

Leases

Income Taxes

Recent Accounting Pronouncements

Stockholders' Equity And Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2020

Stockholders' Equity And Stock-Based Compensation [Abstract]

Warrants Outstanding


			Number of Shares Outstanding under Warrant
			December 31,
Issuance Date	Expiration Date	Exercise Price Per Share	2020	2019

August 17, 2018	February 17, 2021	1.25	554,019	4,496,116
August 17, 2018	February 17, 2021	1.59	—	7,975
			554,019	4,504,091

Stock Option Activity


	Number of Options		Weighted Average Exercise Price	Weighted Average Remaining Contractual Term	Aggregate Intrinsic Value
				In years	In millions
Outstanding as of December 31, 2019	3,210,965	$	12.27	6.05	$	4.2
Options granted	60,000		7.25
Options exercised	(71,105)		3.60
Options forfeited/canceled	(382,356)		20.31
Outstanding as of December 31, 2020	2,817,504		11.30	5.60	$	6.4
Vested and expected to vest at December 31, 2020	2,817,504		11.30	5.60	$	6.4
Exercisable at December 31, 2020	2,167,633	$	13.86	4.85	$	3.7

Information About Stock Options Outstanding


				Options outstanding				Options exercisable
					Weighted
					average	Weighted			Weighted
				Number of	remaining	average		Number of	average
Range of exercise prices				outstanding	contractual	exercise		vested	exercise
From		To		options	life (in years)	price		options	price
$	0.95	$	1.88	659,688	8.4	$	1.47	251,613	$	1.31
$	3.24	$	4.09	812,094	6.7	$	3.51	643,377	$	3.48
$	4.10	$	13.09	598,462	5.0	$	10.89	525,383	$	11.42
$	14.21	$	35.00	619,599	2.8	$	24.02	619,599	$	24.02
$	36.40	$	53.55	127,661	0.7	$	51.72	127,661	$	51.72
				2,817,504	5.6	$	11.30	2,167,633	$	13.86

Weighted Average Fair Value Of Options Granted


	2020	2019
Volatility	123% to 139%	118% to 119%
Risk-free interest rates	0.46% to 0.78%	1.7% to 2.5%
Expected life of option	7 years	7 years
Dividend yield	zero	zero
Forfeiture rate	zero	zero
Weighted average fair value of stock options granted	$6.69	$1.60

Summary Of Performance Award Activity


		Number of Performance Awards
Outstanding as of December 31, 2019		138,055
Granted		—
Vested performance awards		—
Forfeited/Canceled		—
Outstanding as of December 31, 2020		138,055

Non-Cash Stock-Based Compensation Expenses



	Year ended
	December 31,
	2020		2019
Research and development	$	453	$	542

General and administrative		535		754

Total non-cash stock-based compensation expense	$	988	$	1,296

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2020

Income Taxes [Abstract]

Schedule Of Effective Income Tax Rate Reconciliation



	Year ended December 31,
	2020		2019
Tax at federal statutory rate	21.0	%		21.0	%
State tax, net of federal benefit	—			—
Share-based compensation	(42.8)			(2.4)
Research and development credits	1.6			0.6
Change in valuation allowance	20.2			(19.2)
Effective income tax rate	—	%		—	%

Schedule Of Deferred Tax Assets And Valuation Allowance


	December 31,
	2020		2019
Deferred tax assets:
Net operating loss carryforwards	$	18,333	$	17,110
Share-based compensation		3,230		5,817
Research and development credit carryforwards		6,687		6,587
Other		264		237
Total deferred tax assets:		28,514		29,751
Valuation allowance		(28,447)		(29,725)
Net deferred tax assets:		67		26
Deferred tax liabilities:
Property and equipment		(5)		(7)
Operating lease right-of-use assets		(62)		(19)
Total deferred tax liabilities:		(67)		(26)
Net deferred tax asset / (liability):	$	—	$	—

Schedule Of Unrecognized Tax Benefits



		Year ended December 31,
	2020		2019
Beginning balance	$	4,400	$	4,400
Additions based on tax positions related to the current year		100		—
Ending balance	$	4,500	$	4,400

Summary Of Significant Accounting Policies (Numerators And Denominators In The Calculation Of Basic And Diluted Net Loss Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Numerator:
Net loss	$ (6,334)	$ (4,631)
Denominator:
Shares used in computing net loss per share, basic and diluted	26,105	17,412
Net loss per share, basic and diluted	$ (0.24)	$ (0.27)
Stock Option [Member]
Denominator:
Common stock excluded from net loss per share, diluted	2,145	2,932
Warrants [Member]
Denominator:
Common stock excluded from net loss per share, diluted	554	4,504

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

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+ Details

Stockholders' Equity And Stock-Based Compensation (Narrative) (Details) - USD ($)					1 Months Ended	12 Months Ended
	Feb. 12, 2021	Jan. 01, 2021	Nov. 13, 2020	Mar. 27, 2020	Aug. 31, 2018	Dec. 31, 2020	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Proceeds from exercise of warrants						$ 4,940,000	$ 5,866,000
Number of shares execrise						554,019	4,504,091
Award expiration period						4 years
Dividend yield						0.00%	0.00%
Compensation costs prior to forfeiture						$ 1,500,000
Weighted average remaining recognition period						2 years 1 month 6 days
Stock options exercised						71,105
Proceeds from stock options exercised						$ 256,000
Offering of common stock shares						120,000,000	120,000,000
Par value per share						$ 0.001	$ 0.001
Subsequent Event [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options exercised		20,385
Proceeds from stock options exercised		$ 169,000
ATM [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares issued						0
Percentage of commission in ATM offering				3.00%
ATM [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Aggregate offering price				$ 100,000,000
2008 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award expiration period						10 years
2018 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration period of stock options granted						10 years
Offering of common stock shares						1,000,000
Par value per share						$ 0.001
Performance Award [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Additional stock compensation expense						$ 2,300,000
Performance awards vested
Performance Award [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance awards expiration date						Dec. 31, 2026
Performance Award [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance awards expiration date						Jan. 01, 2022
Common Stock [Member] \| 2021 Registered Direct Offering [Member] \| Subsequent Event [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares issued	4,081,633
Price per share	$ 49.00
Net proceeds from offering	$ 189,700,000
Common Stock [Member] \| Public Offering [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares issued			9,375,000
Price per share			$ 8.00
Net proceeds from offering			$ 70,251,000
Warrants [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares execrise						554,019	4,496,116
Warrants [Member] \| Subsequent Event [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Proceeds from exercise of warrants		$ 700,000
Number of shares execrise		600,000
Warrants [Member] \| Common Stock Warrants [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares issued					9,100,000
Proceeds from exercise of warrants						$ 4,900,000	$ 5,900,000
Number of shares execrise						4,000,000	4,600,000
Warrants [Member] \| Common Stock Warrants [Member] \| Subsequent Event [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Proceeds from exercise of warrants		$ 700,000
Number of shares execrise		600,000
Placement Agent Warrants [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares execrise							7,975

Stockholders' Equity And Stock-Based Compensation (Stock Option Activity) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Stockholders' Equity And Stock-Based Compensation [Abstract]
Outstanding as of, Beginning	3,210,965
Options granted	60,000
Options exercised	(71,105)
Options forfeited/canceled	(382,356)
Outstanding as of, Ending	2,817,504	3,210,965
Vested and expected to vest at December 31, 2020	2,817,504
Exercisable at December 31, 2020	2,167,633
Weighted Average Exercise Price, Outstanding as of, Beginning	$ 12.27
Weighted Average Exercise Price, Options granted	7.25
Weighted Average Exercise Price, Options exercised	3.60
Weighted Average Exercise Price, Options forfeited/cancelled	20.31
Weighted Average Exercise Price, Outstanding as of, Ending	11.30	$ 12.27
Weighted Average Exercise Price, Vested and expected to vest at December 31, 2020	11.30
Weighted Average Exercise Price, Exercisable at December 31, 2020	$ 13.86
Weighted Average Remaining Contractual Term	5 years 7 months 6 days	6 years 18 days
Weighted Average Remaining Contractual Term, Vested and expected to vest at December 31, 2020	5 years 7 months 6 days
Weighted Average Remaining Contractual Term, Exercisable at December 31, 2020	4 years 10 months 6 days
Outstanding, Aggregate Intrinsic Value	$ 6.4	$ 4.2
Aggregate Intrinsic Value, Vested and expected to vest at December 31, 2020	6.4
Aggregate Intrinsic Value, Exercisable at December 31, 2020	$ 3.7

Stockholders' Equity And Stock-Based Compensation (Information About Stock Options Outstanding) (Details)	12 Months Ended
	Dec. 31, 2020 $ / shares shares
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of outstanding options, Options outstanding \| shares	2,817,504
Weighted average remaining contractual life (in years), Options outstanding	5 years 7 months 6 days
Weighted average exercise price, Options outstanding	$ 11.30
Number of vested options, Options exercisable \| shares	2,167,633
Weighted average exercise price, Options exercisable	$ 13.86
$0.95 - $1.88 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of exercise prices, Minimum	0.95
Range of exercise prices, Maximum	$ 1.88
Number of outstanding options, Options outstanding \| shares	659,688
Weighted average remaining contractual life (in years), Options outstanding	8 years 4 months 24 days
Weighted average exercise price, Options outstanding	$ 1.47
Number of vested options, Options exercisable \| shares	251,613
Weighted average exercise price, Options exercisable	$ 1.31
$3.24 - $4.09 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of exercise prices, Minimum	3.24
Range of exercise prices, Maximum	$ 4.09
Number of outstanding options, Options outstanding \| shares	812,094
Weighted average remaining contractual life (in years), Options outstanding	6 years 8 months 12 days
Weighted average exercise price, Options outstanding	$ 3.51
Number of vested options, Options exercisable \| shares	643,377
Weighted average exercise price, Options exercisable	$ 3.48
$4.10 - $13.09 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of exercise prices, Minimum	4.10
Range of exercise prices, Maximum	$ 13.09
Number of outstanding options, Options outstanding \| shares	598,462
Weighted average remaining contractual life (in years), Options outstanding	5 years
Weighted average exercise price, Options outstanding	$ 10.89
Number of vested options, Options exercisable \| shares	525,383
Weighted average exercise price, Options exercisable	$ 11.42
$14.21 - $35.00 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of exercise prices, Minimum	14.21
Range of exercise prices, Maximum	$ 35.00
Number of outstanding options, Options outstanding \| shares	619,599
Weighted average remaining contractual life (in years), Options outstanding	2 years 9 months 18 days
Weighted average exercise price, Options outstanding	$ 24.02
Number of vested options, Options exercisable \| shares	619,599
Weighted average exercise price, Options exercisable	$ 24.02
$36.40 - $53.55 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of exercise prices, Minimum	36.40
Range of exercise prices, Maximum	$ 53.55
Number of outstanding options, Options outstanding \| shares	127,661
Weighted average remaining contractual life (in years), Options outstanding	8 months 12 days
Weighted average exercise price, Options outstanding	$ 51.72
Number of vested options, Options exercisable \| shares	127,661
Weighted average exercise price, Options exercisable	$ 51.72

Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating Loss Carryforwards [Line Items]
U.S federal corporate tax rate	21.00%	21.00%
Valuation allowance increase (decrease)	$ (1,300)
Unrecognized tax benefits	4,500	$ 4,400	$ 4,400
Write Down Of Share-Based Compensation [Member]
Operating Loss Carryforwards [Line Items]
Valuation allowance increase (decrease)	(2,400)
Book Losses [Member]
Operating Loss Carryforwards [Line Items]
Valuation allowance increase (decrease)	1,100	$ 900
Federal [Member]
Operating Loss Carryforwards [Line Items]
Pre-tax net operating loss carryforwards	87,300
Federal [Member] \| Expires Between 2029 And 2039 [Member]
Operating Loss Carryforwards [Line Items]
Pre-tax net operating loss carryforwards	74,100
Federal [Member] \| Indefinitely [Member]
Operating Loss Carryforwards [Line Items]
Pre-tax net operating loss carryforwards	13,200
Federal [Member] \| Expires Between 2023 And 2039 [Member]
Operating Loss Carryforwards [Line Items]
Federal research and development tax credits	$ 11,100
Federal [Member] \| Minimum [Member] \| Expires Between 2029 And 2039 [Member]
Operating Loss Carryforwards [Line Items]
Expiration date of pre-tax net operating loss carryforwards	Jan. 01, 2029
Federal [Member] \| Minimum [Member] \| Expires Between 2023 And 2039 [Member]
Operating Loss Carryforwards [Line Items]
Expiration date of federal research and development tax credits	Jan. 01, 2023
Federal [Member] \| Maximum [Member] \| Expires Between 2029 And 2039 [Member]
Operating Loss Carryforwards [Line Items]
Expiration date of pre-tax net operating loss carryforwards	Dec. 31, 2039
Federal [Member] \| Maximum [Member] \| Expires Between 2023 And 2039 [Member]
Operating Loss Carryforwards [Line Items]
Expiration date of federal research and development tax credits	Dec. 31, 2040

Income Taxes (Schedule Of Deferred Tax Assets And Valuation Allowance) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets:
Net operating loss carryforwards	$ 18,333	$ 17,110
Share-based compensation	3,230	5,817
Research and development credit carryforwards	6,687	6,587
Other	264	237
Total deferred tax assets	28,514	29,751
Valuation allowance	(28,447)	(29,725)
Net deferred tax assets:	67	26
Deferred tax liabilities:
Property and equipment	(5)	(7)
Operating lease right-of-use assets	(62)	(19)
Total deferred tax liabilities:	(67)	(26)
Net deferred tax asset / (liability):

General And Liquidity	12 Months Ended
General And Liquidity	Dec. 31, 2020
General And Liquidity [Abstract]
General And Liquidity	1. General and Liquidity Cassava Sciences, Inc. (the Company), formerly known as Pain Therapeutics, Inc., develops proprietary products that offer significant improvements to patients and healthcare professionals. The Company generally focuses its product development efforts on disorders of the nervous system. Coronavirus Disease 2019 (COVID-19) The recent, widespread outbreak of a novel infectious disease called Coronavirus Disease 2019, or COVID-19, has not significantly impacted the Company’s operations or financial condition as of March 23, 2021. However, this pandemic has created a dynamic and uncertain situation in the national economy. The Company continues to closely monitor the latest information to make timely, informed business decisions and public disclosures regarding the potential impact of pandemic on its operations and financial condition. The scope of pandemic is unprecedented and its long-term impact on the Company’s operations and financial condition cannot be reasonably estimated at this time. Liquidity The Company has incurred significant net losses and negative cash flows since inception, and as a result has an accumulated deficit of $174.9 million at December 31, 2020. The Company expects its cash requirements to be significant in the future. The amount and timing of its future cash requirements will depend on regulatory and market acceptance of the Company’s product candidates and the resources it devotes to researching and developing, formulating, manufacturing, commercializing and supporting its products. The Company may seek additional future funding through public or private financing in the future, if such funding is available and on terms acceptable to the Company. There are no assurances that additional financing will be available on favorable terms, or at all. However, management believes that the current working capital position will be sufficient to meet the Company’s working capital needs for at least the next 12 months.

Property And Equipment	12 Months Ended
Property And Equipment	Dec. 31, 2020
Property And Equipment [Abstract]
Property And Equipment	3. Property and Equipment The Company’s property and equipment include furniture and equipment. Depreciation is recognized using the straight-line method over the expected life of the property and equipment. During the year ended December 31, 2020, the Company sold surplus manufacturing equipment to an independent third party and received proceeds totaling $360,000. The original cost of the property and equipment was $892,000 and accumulated depreciation was $878,000, resulting a gain on sale of property and equipment of $346,000 during the year ended December 31, 2020. There were no sales of property and equipment during year ended December 31, 2019.

Employee 401(k) Benefit Plan	12 Months Ended
Employee 401(k) Benefit Plan	Dec. 31, 2020
Employee 401(k) Benefit Plan [Abstract]
Employee 401(k) Benefit Plan	5. Employee 401(k) Benefit Plan The Company has a defined-contribution savings plan under Section 401(k) of the Internal Revenue Code. The plan covers substantially all employees. Employees are eligible to participate in the plan the first day of the month after hire and may contribute up to the current statutory limits under Internal Revenue Service regulations. The 401(k) plan permits the Company to make additional matching contributions on behalf of all employees. Through December 31, 2020, the Company has not made any matching contributions to the 401(k) plan.

2020 Cash Incentive Bonus Plan	12 Months Ended
2020 Cash Incentive Bonus Plan	Dec. 31, 2020
Cash Incentive Bonus Plan [Abstract]
2020 Cash Incentive Bonus Plan	Note 8. 2020 Cash Incentive Bonus Plan On August 26, 2020, the Board approved the Plan. The Plan was established to promote the long-term success of the Company by creating an “at-risk” cash bonus program that rewards Plan participants with additional cash compensation in lockstep with significant increases in the Company’s market capitalization. The Plan is considered “at-risk” because Plan participants will not receive a cash bonus unless the Company’s market capitalization increases significantly and certain other conditions specified in the Plan are met. Specifically, Plan participants will not be paid any cash bonuses unless (1) the Company completes a merger or acquisition transaction that constitutes a sale of ownership of the Company or its assets (a Merger Transaction) or (2) the Compensation Committee of the Board (the Compensation Committee) determines the Company has sufficient cash on hand, as defined in the Plan. Because of the inherent discretion and uncertainty regarding these requirements, the Company has concluded that a Plan grant date has not occurred as of December 31, 2020. Plan participants will be paid all earned cash bonuses in the event of a Merger Transaction. The Company’s market capitalization for purposes of the Plan is determined based on either (1) the Company’s closing price of one share on the Nasdaq Capital Market multiplied by the total issued and outstanding shares and options to purchase shares of the Company or (2) the aggregate consideration payable to security holders of the Company in a Merger Transaction. This constitutes a market condition under applicable accounting guidance. The Plan triggers a potential cash bonus each time the Company’s market capitalization increases significantly, up to a maximum $5 billion in market capitalization. The Plan specifies 14 incremental amounts between $200 million and $5 billion (each increment, a “Valuation Milestone”). Each Valuation Milestone triggers a potential cash bonus award in a pre-set amount defined in the Plan. Each Valuation Milestone must be achieved and maintained for no less than 20 consecutive trading days for Plan participants to be eligible for a potential cash bonus award. Approximately 59% of each cash bonus award associated with a Valuation Milestone is subject to adjustment and approval by the Compensation Committee. Any amounts not awarded by the Compensation Committee are no longer available for distribution. If the Company were to exceed a $5 billion market capitalization for no less than 20 consecutive trading days, all Valuation Milestones would be deemed achieved, in which case cash bonus awards would range from a minimum of $137.4 million up to a hypothetical maximum of $322.3 million. Payment of cash bonuses is deferred until such time as (1) the Company completes a Merger Transaction, or (2) the Compensation Committee determines the Company has sufficient cash on hand to render payment (each, a “Performance Condition”), neither of which may ever occur. Accordingly, there can be no assurance that Plan participants will ever be paid a cash bonus that is awarded under the Plan, even if the Company’s market capitalization increases significantly. The Plan is accounted for as a liability award. The fair value of each Valuation Milestone award will be determined once a grant date occurs and will be remeasured each reporting period. Compensation expense associated with the Plan will be recognized over the expected achievement period for each of the 14 Valuation Milestones, when a Performance Condition is considered probable of being met. On October 13, 2020, the Company achieved the first Valuation Milestone. Subsequently, the Compensation Committee approved a potential cash bonus award of $7.3 million in total for all Plan participants, subject to future satisfaction of a Performance Condition. However, no compensation expense has been recorded since no grant date has occurred and no Performance Conditions are considered probable of being met. There is no continuing service requirement for Plan participants once the Compensation Committee approves a cash bonus award. Subsequent to December 31, 2020, the Company achieved eight additional Valuation Milestones triggering potential Company obligations to all Plan participants from a minimum of $59.9 million up to a hypothetical maximum of $145.0 million, to be determined by the Compensation Committee and contingent upon future satisfaction of a Performance Condition. No actual cash payments were authorized or made to participants under the Plan during the year ended December 31, 2020.

General And Liquidity (Narrative) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
General And Liquidity [Abstract]
Accumulated deficit	$ 174,921	$ 168,587

Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2020	Dec. 31, 2019
Balance Sheets [Abstract]
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	120,000,000	120,000,000
Common stock, shares issued	35,237,987	21,841,810
Common stock, shares outstanding	35,237,987	21,841,810

Summary Of Significant Accounting Policies (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($) segment	Dec. 31, 2019 USD ($)
Summary Of Significant Accounting Policies [Abstract]
Certificate of deposit	$ 13.0
Reimbursement from National Institutes of Health research grants	$ 4.2	$ 4.7
Number of business segments \| segment	1
Vesting period of stock options	4 years

Property And Equipment (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Gain on sale of property and equipment	$ 346
Manufacturing Equipment [Member]
Property, Plant and Equipment [Line Items]
Proceeds from sale of equipment	360
Property and equipment, original cost	892
Accumulated depreciation	878
Gain on sale of property and equipment	$ 346

Stockholders' Equity And Stock-Based Compensation (Summary Of Performance Award Activity) (Details) - Performance Award [Member]	12 Months Ended
	Dec. 31, 2020 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding as of, Beginning	138,055
Granted
Vested performance awards
Forfeited/Cancelled
Outstanding as of, Ending	138,055

Stockholders' Equity And Stock-Based Compensation (Non-Cash Stock-Based Compensation Expenses) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total non-cash stock-based compensation expense	$ 988	$ 1,296
Research and development [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total non-cash stock-based compensation expense	453	542
General and administrative [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total non-cash stock-based compensation expense	$ 535	$ 754

Leases And Commitments (Narrative) (Details) $ in Thousands	12 Months Ended
Leases And Commitments (Narrative) (Details) $ in Thousands	Dec. 31, 2020 USD ($) ft²	Dec. 31, 2019 USD ($)	Sep. 30, 2020 USD ($)
Leases And Commitments [Line Items]
Rent expense	$ 100	$ 100
Operating lease right-of-use assets	295	90	$ 316
Operating lease liability	293		$ 316
Leases, discount rate			3.25%
Right-of-use assets exchange for operating lease liabilities		0
Cash paid for operating lease liabilities	$ 99	$ 95
Austin [Member]
Leases And Commitments [Line Items]
Office space \| ft²	6,000
Lease expiration date	Apr. 30, 2024

Leases And Commitments (Future Minimum Lease Payments) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Sep. 30, 2020
For the year ending December 31,
2021	$ 66
2022	102
2023	107
2024	36
Total future minimum lease payments	311
Less: imputed interest	(18)
Total	$ 293	$ 316

2020 Cash Incentive Bonus Plan (Narrative) (Details) - Cash Incentive Bonus Plan [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Jan. 01, 2021	Oct. 13, 2020
Cash Incentive Bonus Plan [Line Items]
Percentage of each cash bonus award associated with Valuation Milestone subject to adjustment and approval	59.00%
Payments authorized or made to participants under the Plan	$ 0.0
First Valuation Milestone [Member]
Cash Incentive Bonus Plan [Line Items]
Cash bonus award			$ 7.3
Minimum [Member]
Cash Incentive Bonus Plan [Line Items]
Valuation milestone amount in market capitalization	200.0
Minimum [Member] \| Exceeds $5 Billion Market Capitalization For No Less Than 20 Consecutive Trading Days [Member]
Cash Incentive Bonus Plan [Line Items]
Cash bonus award	137.4
Minimum [Member] \| Second Through Eighth Valuation Milestones [Member] \| Subsequent Event [Member]
Cash Incentive Bonus Plan [Line Items]
Cash bonus award		$ 59.9
Maximum [Member]
Cash Incentive Bonus Plan [Line Items]
Valuation milestone amount in market capitalization	5,000.0
Maximum [Member] \| Exceeds $5 Billion Market Capitalization For No Less Than 20 Consecutive Trading Days [Member]
Cash Incentive Bonus Plan [Line Items]
Cash bonus award	$ 322.3
Maximum [Member] \| Second Through Eighth Valuation Milestones [Member] \| Subsequent Event [Member]
Cash Incentive Bonus Plan [Line Items]
Cash bonus award		$ 145.0