Cardiff Oncology (CRDF) 10-Q 2 Nov 23 2023 Q3 Quarterly report Financial data

Cover Page

Cover Page - shares	9 Months Ended
	Sep. 30, 2023	Oct. 26, 2023
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Transition Report	false
Document Period End Date	Sep. 30, 2023
Entity File Number	001-35558
Entity Registrant Name	CARDIFF ONCOLOGY, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	27-2004382
Entity Address, Address Line One	11055 Flintkote Avenue
Entity Address, City or Town	San Diego
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	92121
City Area Code	858
Local Phone Number	952-7570
Title of 12(b) Security	Common Stock
Trading Symbol	CRDF
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
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		44,677,169
Entity Central Index Key	0001213037
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q3
Security Exchange Name	NASDAQ

CONDENSED BALANCE SHEETS

CONDENSED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 15,233	$ 16,347
Short-term investments	66,130	88,920
Accounts receivable and unbilled receivable	198	771
Prepaid expenses and other current assets	2,344	5,246
Total current assets	83,905	111,284
Property and equipment, net	1,317	1,269
Operating lease right-of-use assets	1,843	2,251
Other assets	1,387	1,387
Total Assets	88,452	116,191
Current liabilities:
Accounts payable	2,179	1,956
Accrued liabilities	6,151	5,177
Operating lease liabilities	688	675
Total current liabilities	9,018	7,808
Operating lease liabilities, net of current portion	1,607	2,040
Total Liabilities	10,625	9,848
Commitments and contingencies (Note 6)
Stockholders’ equity
Preferred stock, 20,000 shares authorized; 277,100 designated as Series A Convertible Preferred Stock; 60,600 shares outstanding at September 30, 2023 and December 31, 2022 with liquidation preference of $1,062 and $1,044 at September 30, 2023 and December 31, 2022, respectively (Note 5)	0	0
Common stock, $0.0001 par value, 150,000 shares authorized; 44,677 shares issued and outstanding at September 30, 2023 and December 31, 2022	4	4
Additional paid-in capital	408,434	404,834
Accumulated other comprehensive loss	(407)	(395)
Accumulated deficit	(330,204)	(298,100)
Total stockholders’ equity	77,827	106,343
Total liabilities and stockholders’ equity	$ 88,452	$ 116,191

CONDENSED BALANCE SHEETS (Paren

CONDENSED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Preferred stock, shares authorized (in shares)	20,000,000	20,000,000
Temporary equity, shares outstanding (in shares)	60,600	60,600
Preferred stock, liquidation preference, value	$ 1,062	$ 1,044
Common stock, par value (in USD per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	150,000,000	150,000,000
Common stock, shares issued (in shares)	44,677,000	44,677,000
Common stock, shares outstanding (in shares)	44,677,000	44,677,000
Temporary Equity, Shares Authorized	277,100	277,100

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Income Statement [Abstract]
Royalties	$ 141	$ 93	$ 332	$ 258
Costs and expenses:
Research and development	8,022	6,009	25,094	20,665
Selling, general and administrative	2,939	3,077	10,318	10,103
Total operating expenses	10,961	9,086	35,412	30,768
Loss from operations	(10,820)	(8,993)	(35,080)	(30,510)
Interest income, net	1,068	458	3,061	841
Other income (expense), net	21	(36)	(85)	(338)
Total other income (expense), net	1,089	422	2,976	503
Net loss	(9,731)	(8,571)	(32,104)	(30,007)
Preferred stock dividend payable on Series A Convertible Preferred Stock	(6)	(6)	(18)	(18)
Net loss attributable to common stockholders	$ (9,737)	$ (8,577)	$ (32,122)	$ (30,025)
Net loss per common share - basic (in dollars per share)	$ (0.22)	$ (0.20)	$ (0.72)	$ (0.69)
Net loss per common share - diluted (in dollars per share)	$ (0.22)	$ (0.20)	$ (0.72)	$ (0.69)
Weighted-average shares outstanding - basic (in shares)	44,677	43,333	44,677	43,291
Weighted-average shares outstanding - diluted (in shares)	44,677	43,333	44,677	43,291

CONDENSED STATEMENTS OF COMPREH

CONDENSED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Statement of Comprehensive Income [Abstract]
Net loss	$ (9,731)	$ (8,571)	$ (32,104)	$ (30,007)
Other comprehensive loss:
Unrealized gain (loss) on securities available-for-sale	24	203	(12)	(637)
Total comprehensive loss	(9,707)	(8,368)	(32,116)	(30,644)
Preferred stock dividend payable on Series A Convertible Preferred Stock	(6)	(6)	(18)	(18)
Comprehensive loss attributable to common stockholders	$ (9,713)	$ (8,374)	$ (32,134)	$ (30,662)

CONDENSED STATEMENT OF STOCKHOL

CONDENSED STATEMENT OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Preferred Stock	Common Stock	Additional Paid-In Capital	Service Receivable	Accumulated Other Comprehensive Loss	Accumulated Deficit
Balance, beginning (in shares) at Dec. 31, 2021		716	41,964
Balance, beginning at Dec. 31, 2021	$ 140,417	$ 1	$ 4	$ 400,503	$ (139)	$ (142)	$ (259,810)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	1,152			1,152
Other comprehensive gain (loss)	(606)					(606)
Issuance of common stock upon conversion of Series E Convertible Preferred Stock (in shares)		(328)	1,342
Issuance of common stock upon conversion of Series E Convertible Preferred Stock	(1)	$ (1)
Preferred stock dividend	(6)						(6)
Release of clinical trial funding commitment	139				139
Net loss	(10,993)						(10,993)
Balance, ending (in shares) at Mar. 31, 2022		388	43,306
Balance, ending at Mar. 31, 2022	130,102	$ 0	$ 4	401,655	0	(748)	(270,809)
Balance, beginning (in shares) at Dec. 31, 2021		716	41,964
Balance, beginning at Dec. 31, 2021	140,417	$ 1	$ 4	400,503	(139)	(142)	(259,810)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(30,007)
Balance, ending (in shares) at Sep. 30, 2022		388	43,335
Balance, ending at Sep. 30, 2022	113,212	$ 0	$ 4	403,822	0	(779)	(289,835)
Balance, beginning (in shares) at Mar. 31, 2022		388	43,306
Balance, beginning at Mar. 31, 2022	130,102	$ 0	$ 4	401,655	0	(748)	(270,809)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	1,055			1,055
Other comprehensive gain (loss)	(234)					(234)
Preferred stock dividend	(6)						(6)
Net loss	(10,443)						(10,443)
Balance, ending (in shares) at Jun. 30, 2022		388	43,306
Balance, ending at Jun. 30, 2022	120,474	$ 0	$ 4	402,710	0	(982)	(281,258)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	1,037			1,037
Issuance of common stock upon exercise of stock options	75			75
Issuance of common stock upon exercise of stock options (in shares)			29
Other comprehensive gain (loss)	203					203
Preferred stock dividend	(6)						(6)
Net loss	(8,571)						(8,571)
Balance, ending (in shares) at Sep. 30, 2022		388	43,335
Balance, ending at Sep. 30, 2022	113,212	$ 0	$ 4	403,822	$ 0	(779)	(289,835)
Balance, beginning (in shares) at Dec. 31, 2022		61	44,677
Balance, beginning at Dec. 31, 2022	106,343	$ 0	$ 4	404,834		(395)	(298,100)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	1,064			1,064
Other comprehensive gain (loss)	319					319
Net loss	(11,223)						(11,223)
Balance, ending (in shares) at Mar. 31, 2023		61	44,677
Balance, ending at Mar. 31, 2023	96,503	$ 0	$ 4	405,898		(76)	(309,323)
Balance, beginning (in shares) at Dec. 31, 2022		61	44,677
Balance, beginning at Dec. 31, 2022	106,343	$ 0	$ 4	404,834		(395)	(298,100)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(32,104)
Balance, ending (in shares) at Sep. 30, 2023		61	44,677
Balance, ending at Sep. 30, 2023	77,827	$ 0	$ 4	408,434		(407)	(330,204)
Balance, beginning (in shares) at Mar. 31, 2023		61	44,677
Balance, beginning at Mar. 31, 2023	96,503	$ 0	$ 4	405,898		(76)	(309,323)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	1,581			1,581
Other comprehensive gain (loss)	(355)					(355)
Net loss	(11,150)						(11,150)
Balance, ending (in shares) at Jun. 30, 2023		61	44,677
Balance, ending at Jun. 30, 2023	86,579	$ 0	$ 4	407,479		(431)	(320,473)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	955			955
Other comprehensive gain (loss)	24					24
Net loss	(9,731)						(9,731)
Balance, ending (in shares) at Sep. 30, 2023		61	44,677
Balance, ending at Sep. 30, 2023	$ 77,827	$ 0	$ 4	$ 408,434		$ (407)	$ (330,204)

CONDENSED STATEMENTS OF CASH FL

CONDENSED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Operating activities
Net loss	$ (32,104)	$ (30,007)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	295	150
Stock-based compensation expense	3,600	3,244
Amortization of premiums (discounts) on short-term investments	(716)	672
Release of clinical trial funding commitment	0	139
Changes in operating assets and liabilities:
Other assets	0	55
Accounts receivable and unbilled receivable	573	(115)
Prepaid expenses and other current assets	3,188	4
Operating lease right-of-use assets	408	408
Accounts payable and accrued expenses	1,428	1,325
Operating lease liabilities	(420)	(271)
Other liabilities	0	(34)
Net cash used in operating activities	(23,748)	(24,430)
Investing activities:
Capital expenditures	(574)	(931)
Insurance proceeds from casualty loss	0	114
Maturities of short-term investments	80,534	61,229
Purchases of short-term investments	(67,491)	(80,428)
Sales of short-term investments	10,165	51,145
Net cash provided by investing activities	22,634	31,129
Financing activities:
Proceeds from exercise of options	0	75
Net cash provided by financing activities	0	75
Net change in cash and cash equivalents	(1,114)	6,774
Cash and cash equivalents—Beginning of period	16,347	11,943
Cash and cash equivalents—End of period	15,233	18,717
Supplemental disclosure of non-cash investing and financing activities:
Acquisition of property and equipment included in accounts payable and accrued expenses	$ 0	$ 255

Organization and Basis of Prese

Organization and Basis of Presentation	9 Months Ended
	Sep. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Basis of Presentation	Organization and Basis of Presentation Business Organization and Overview Cardiff Oncology, Inc. (“Cardiff Oncology” or the “Company”) headquartered in San Diego, California, is a clinical-stage biotechnology company leveraging Polo-like Kinase 1 (“PLK1”) inhibition to develop novel therapies across a range of cancers. The Company’s lead asset is onvansertib, a PLK1 inhibitor that is being evaluated in combination with standard-of-care therapies in clinical programs targeting indications such as RAS-mutated metastatic colorectal cancer, metastatic pancreatic cancer, as well as investigator-initiated trials in small cell lung cancer and triple negative breast cancer. These programs and the Company’s broader development strategy are designed to target tumor vulnerabilities in order to overcome treatment resistance and deliver superior clinical benefit compared to the standard-of-care alone. The Company's common stock is listed on the Nasdaq Capital Market under the ticker symbol "CRDF". Basis of Presentation The accompanying unaudited interim condensed financial statements of Cardiff Oncology have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) and the rules and regulations of the Securities and Exchange Commission (“SEC”) related to a quarterly report on Form 10-Q. Certain information and note disclosures normally included in annual financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to those rules and regulations. The unaudited interim condensed financial statements reflect all adjustments consisting of normal recurring adjustments which, in the opinion of management, are necessary for a fair statement of the Company’s financial position and the results of its operations and cash flows for the periods presented. The unaudited condensed balance sheet at December 31, 2022, has been derived from the audited financial statements at that date but does not include all of the information and disclosures required by GAAP for annual financial statements. The operating results presented in these unaudited interim condensed financial statements are not necessarily indicative of the results that may be expected for any future periods. These unaudited interim condensed financial statements should be read in conjunction with the audited financial statements and the notes thereto for the year ended December 31, 2022, included in the Company’s annual report on Form 10-K filed with the SEC on March 2, 2023. Liquidity The Company has incurred net losses since its inception and has negative operating cash flows. As of September 30, 2023, the Company had $81.4 million in cash, cash equivalents and short-term investments and believes it has sufficient cash to meet its funding requirements for at least the next 12 months following the issuance date of these financial statements.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2023
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies During the nine months ended September 30, 2023, there have been no changes to the Company’s significant accounting policies as described in its Annual Report on Form 10-K for the fiscal year ended December 31, 2022. Net Loss Per Share Basic and diluted net loss per common share is determined by dividing net loss applicable to common stockholders by the weighted-average common shares outstanding during the period. Preferred dividends are included in net loss attributable to common stockholders in the computation of basic and diluted earnings per share. The following table sets forth the outstanding potentially dilutive securities that have been excluded in the calculation of diluted net loss per share because their effect was anti-dilutive: September 30, 2023 2022 Options to purchase Common Stock 6,652,427 5,101,572 Warrants to purchase Common Stock 2,807,948 4,490,159 Series A Convertible Preferred Stock 877 877 Series E Convertible Preferred Stock — 1,342,250 9,461,252 10,934,858 Recent Accounting Pronouncement Not Yet Adopted In August 2020, the FASB issued ASU No. 2020-06 ("ASU 2020-06"), Debt - Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging - Contracts in Entity’s Own Equity (Subtopic 815-40) (“ASU 2020-06”). ASU 2020-06 eliminates the beneficial conversion and cash conversion accounting models for convertible instruments. It also amends the accounting for certain contracts in an entity’s own equity that are currently accounted for as derivatives because of specific settlement provisions. In addition, ASU 2020-06 modifies how particular convertible instruments and certain contracts that may be settled in cash or shares impact the diluted EPS computation. The amendments in this update are effective for public business entities for fiscal years beginning after December 15, 2021 (or December 15, 2023, for companies who meet the SEC definition of Smaller Reporting Companies), and interim periods within those fiscal years. The amendment is to be adopted through either a fully retrospective or modified retrospective method of transition. Early adoption is permitted. The Company is currently evaluating the impact of this standard on its financial statements and related disclosures, and will adopt this standard on January 1, 2024.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2023
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements The following table presents the Company’s assets and liabilities that are measured and recognized at fair value on a recurring basis classified under the appropriate level of the fair value hierarchy as of September 30, 2023, and December 31, 2022: Fair Value Measurements at (in thousands) Quoted Prices in Active Markets for Identical Assets and Liabilities Significant Other Observable Inputs Significant Unobservable Inputs Total Assets: Money market fund $ 14,928 $ — $ — $ 14,928 Total included in cash and cash equivalents 14,928 — — 14,928 Available for sale investments: Certificate of deposit — 9,181 — 9,181 Corporate debt securities — 22,368 — 22,368 Commercial paper — 7,613 — 7,613 U.S. government agencies — 6,821 — 6,821 U.S. treasury securities 20,147 — — 20,147 Total available for sale investments 20,147 45,983 — 66,130 Total assets measured at fair value on a recurring basis $ 35,075 $ 45,983 $ — $ 81,058 Fair Value Measurements at (in thousands) Quoted Prices in Active Markets for Identical Assets and Liabilities Significant Other Observable Inputs Significant Unobservable Inputs Total Assets: Money market fund $ 15,722 $ — $ — $ 15,722 Total included in cash and cash equivalents 15,722 — — 15,722 Available for sale investments: Certificate of deposit — 16,023 — 16,023 Corporate debt securities — 49,535 — 49,535 Commercial paper — 13,187 — 13,187 U.S. government agencies — 2,288 — 2,288 U.S. treasury securities 7,887 — — 7,887 Total available for sale investments 7,887 81,033 — 88,920 Total assets measured at fair value on a recurring basis $ 23,609 $ 81,033 $ — $ 104,642

Supplementary Balance Sheet Inf

Supplementary Balance Sheet Information	9 Months Ended
	Sep. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Supplementary Balance Sheet Information	Supplementary Balance Sheet Information Investments available for sale Investments available for sale consist of the following: As of September 30, 2023 (in thousands) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Market Value Maturity less than 1 year: Certificate of deposit $ 9,181 $ 3 $ (3) $ 9,181 Corporate debt securities 12,194 3 (28) 12,169 Commercial paper 7,616 — (3) 7,613 U.S. government agencies 6,852 — (31) 6,821 U.S. treasury securities 1,935 — (13) 1,922 Total maturity less than 1 year 37,778 6 (78) 37,706 Maturity 1 to 2 years: Corporate debt securities 10,281 3 (85) 10,199 U.S. treasury securities 18,478 — (253) 18,225 Total maturity 1 to 2 years 28,759 3 (338) 28,424 Total short-term investments $ 66,537 $ 9 $ (416) $ 66,130 As of December 31, 2022 (in thousands) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Market Value Maturity less than 1 year: Certificate of deposit $ 16,101 $ 3 $ (81) $ 16,023 Corporate debt securities 44,806 8 (275) 44,539 Commercial paper 13,203 4 (20) 13,187 Non U.S. government 2,284 4 — 2,288 U.S. treasury securities 7,905 — (18) 7,887 Total maturity less than 1 year 84,299 19 (394) 83,924 Maturity 1 to 2 years: Corporate debt securities 5,016 1 (21) 4,996 Total maturity 1 to 2 years 5,016 1 (21) 4,996 Total short-term investments $ 89,315 $ 20 $ (415) $ 88,920 We periodically review our portfolio of debt securities to determine if any investment is impaired due to credit loss or other potential valuation concerns. For debt securities where the fair value of the investment is less than the amortized cost basis, we have assessed at the individual security level for various quantitative factors including, but not limited to, the nature of the investments, changes in credit ratings, interest rate fluctuations, industry analyst reports, and the severity of impairment. Unrealized losses in investments available for sale debt securities at September 30, 2023, were substantially due to increases in interest rates, not due to increased credit risks associated with specific securities. Accordingly, we have not recorded an allowance for credit losses. It is not more likely than not that we will be required to sell the investments before recovery of their amortized cost bases, which may be at maturity. Investments available for sale that have been in a continuous unrealized loss position for greater than one-year consist of the following: As of September 30, 2023 (in thousands) Fair Market Value Gross Unrealized Loss Corporate debt securities $ 1,794 $ (10) Property and equipment Property and equipment consist of the following: (in thousands) As of September 30, As of December 31, Furniture and office equipment $ 1,081 $ 1,066 Leasehold improvements 2,568 2,560 Laboratory equipment 1,332 1,056 4,981 4,682 Less—accumulated depreciation and amortization (3,664) (3,413) Property and equipment, net $ 1,317 $ 1,269 Accrued Liabilities Accrued liabilities consisted of the following: (in thousands) As of September 30, As of December 31, Accrued compensation $ 2,455 $ 1,849 Clinical trials 2,878 2,333 Research agreements and services 591 509 Director fees 125 125 Patent, license and other fees 33 24 Other accrued liabilities 69 337 Total accrued liabilities $ 6,151 $ 5,177

Stockholders' Equity

Stockholders' Equity	9 Months Ended
	Sep. 30, 2023
Stockholders' Equity Note [Abstract]
Stockholders' Equity	Stockholders’ Equity Stock Options Stock-based compensation expense related to Cardiff Oncology equity awards have been recognized in operating results as follows: Three Months Ended September 30, Nine Months Ended September 30, (in thousands) 2023 2022 2023 2022 Included in research and development expense $ 294 $ 286 $ 985 $ 746 Included in selling, general and administrative expense 661 751 2,615 2,498 Total stock-based compensation expense $ 955 $ 1,037 $ 3,600 $ 3,244 The unrecognized compensation cost related to non-vested stock options outstanding at September 30, 2023, net of estimated forfeitures, was $7.5 million, which is expected to be recognized over a weighted-average remaining vesting period of 2.3 years. The weighted-average remaining contractual term of outstanding options as of September 30, 2023, was approximately 8.1 years. The total fair value of stock options vested during the nine months ended September 30, 2023 and 2022, were $4.0 million and $4.0 million, respectively. The estimated fair value of stock option awards was determined on the date of grant using the Black-Scholes option valuation model with the following weighted-average assumptions during the following periods indicated: Nine Months Ended September 30, 2023 2022 Risk-free interest rate 3.62 % 1.87 % Dividend yield 0 % 0 % Expected volatility of Cardiff Oncology common stock 109 % 106 % Expected term (1) 5.3 years 6.0 years (1) The expected term for options granted after January 1, 2023 is estimated based on the Company's historical employee data. Prior to January 1, 2023, the Company used the "simplified method" to estimate expected term. A summary of stock option activity and changes in stock options outstanding is presented below: Total Options Weighted-Average Intrinsic Balance outstanding, December 31, 2022 5,069,458 $ 5.92 $ 19,322 Granted 2,138,624 $ 1.70 Forfeited and expired (555,655) $ 8.40 Balance outstanding, September 30, 2023 6,652,427 $ 4.36 $ 18,747 Exercisable at September 30, 2023 2,944,474 $ 5.88 $ 18,169 Vested and expected to vest at September 30, 2023 6,459,779 $ 4.42 $ 18,718 2021 Equity Incentive Plan In June 2021 the Company's stockholders approved the 2021 Omnibus Equity Incentive Plan ("2021 Plan"). The number of authorized shares in the 2021 Plan is equal to the sum of (i) 3,150,000 shares, plus (ii) the number of shares of Common Stock reserved, but unissued under the 2014 Plan; and (iii) the number of shares of Common Stock underlying forfeited awards under the 2014 Plan. On June 9, 2022, the shareholders approved an increase of shares authorized in the 2021 Plan to 5,150,000 from 3,150,000. As of September 30, 2023, there were 2,013,871 shares available for issuance under the 2021 Plan. 2014 Equity Incentive Plan Subsequent to the adoption of the 2021 Plan, no additional equity awards can be made under the terms of the 2014 Plan. Inducement Grants The Company issues equity awards to certain new employees as inducement grants outside of its 2021 Plan. As of September 30, 2023, an aggregate of 1,435,256 shares were issuable upon the exercise of inducement grant stock options approved by the Company. Modification of Stock Options In June 2023 the Company modified stock options for a departing employee. The modification resulted in an incremental stock-based compensation expense of $0.6 million during the nine month period ended September 30, 2023. Warrants A summary of warrant activity and changes in warrants outstanding, including both liability and equity classifications is presented below: Total Warrants Weighted-Average Weighted-Average Balance outstanding, December 31, 2022 4,360,968 $ 5.33 2.1 years Expired (1,553,020) $ 10.54 Balance outstanding, September 30, 2023 2,807,948 $ 2.45 2.2 years Preferred Stock On August 8, 2023, the Company filed, with the Secretary of State of the State of Delaware, a Certificate of Elimination (the “Certificate of Elimination”) of Series B, Series C, Series D and Series E Convertible Preferred Stock removing the designation and other references to its Series B, Series C, Series D and Series E Convertible Preferred Stock from the Company’s Amended and Restated Certificate of Incorporation, as amended. The Certificate of Elimination eliminates and returns the 8,860 Series B, 200,000 Series C, 154,670 Series D and 865,824 Series E shares of preferred stock previously designated, and no longer issued and outstanding, to the status of authorized but unissued shares of preferred stock, without designation.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2023
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Executive Agreements Certain executive agreements provide for severance payments in case of terminations without cause or certain change of control scenarios. Research and Development Agreements In March 2017, the Company entered into a license agreement with Nerviano which granted the Company development and commercialization rights to NMS-1286937, which Cardiff Oncology refers to as onvansertib. Terms of the agreement also provide for the Company to pay development and commercial milestones, and royalties based on sales volume. These potential development milestones include: (a) dosing of the first subject in the first Phase III Clinical Trial for the first Product, a registration enabling Phase II Clinical Trial, or after completion of a Phase II Clinical Trial that is used as the basis for an NDA submission; and (b) upon filing of the first NDA or equivalent for the first product candidate. During the nine months ended September 30, 2023 and 2022 no milestone or royalty payments were made. The Company is a party to various agreements under which it licenses technology on an exclusive basis in the field of oncology therapeutics. These agreements include License fees, Royalties and Milestone payments. The Company also has a legacy license agreement in the field of oncology diagnostics under which royalty payments are due. These royalty payments are calculated as a percent of revenue. For the nine months ended September 30, 2023 and 2022, payments have not been material. Litigation Cardiff Oncology does not believe that it has legal liabilities that are probable or reasonably possible that require either accrual or disclosure. From time to time, the Company may become involved in various lawsuits and legal proceedings that arise in the ordinary course of business. Litigation is subject to inherent uncertainties, and an adverse result in matters may arise from time to time that may harm the Company’s business. As of the date of this report, management believes that there are no claims against the Company, which it believes will result in a material adverse effect on the Company’s business or financial condition.

Pay vs Performance Disclosure

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2023	Sep. 30, 2022
Pay vs Performance Disclosure
Net loss	$ (9,731)	$ (11,150)	$ (11,223)	$ (8,571)	$ (10,443)	$ (10,993)	$ (32,104)	$ (30,007)

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2023
Accounting Policies [Abstract]
Net Loss Per Share	Net Loss Per Share
Recently Adopted Accounting Pronouncement and Recent Accounting Pronouncement Not Yet Adopted	Recent Accounting Pronouncement Not Yet Adopted In August 2020, the FASB issued ASU No. 2020-06 ("ASU 2020-06"), Debt - Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging - Contracts in Entity’s Own Equity (Subtopic 815-40) (“ASU 2020-06”). ASU 2020-06 eliminates the beneficial conversion and cash conversion accounting models for convertible instruments. It also amends the accounting for certain contracts in an entity’s own equity that are currently accounted for as derivatives because of specific settlement provisions. In addition, ASU 2020-06 modifies how particular convertible instruments and certain contracts that may be settled in cash or shares impact the diluted EPS computation. The amendments in this update are effective for public business entities for fiscal years beginning after December 15, 2021 (or December 15, 2023, for companies who meet the SEC definition of Smaller Reporting Companies), and interim periods within those fiscal years. The amendment is to be adopted through either a fully retrospective or modified retrospective method of transition. Early adoption is permitted. The Company is currently evaluating the impact of this standard on its financial statements and related disclosures, and will adopt this standard on January 1, 2024.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2023
Accounting Policies [Abstract]
Schedule of Antidilutive Securities Excluded from the Calculation of Diluted Net Loss per Share	The following table sets forth the outstanding potentially dilutive securities that have been excluded in the calculation of diluted net loss per share because their effect was anti-dilutive: September 30, 2023 2022 Options to purchase Common Stock 6,652,427 5,101,572 Warrants to purchase Common Stock 2,807,948 4,490,159 Series A Convertible Preferred Stock 877 877 Series E Convertible Preferred Stock — 1,342,250 9,461,252 10,934,858

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2023
Fair Value Disclosures [Abstract]
Schedule of the Company’s Assets and Liabilities that are Measured and Recognized at Fair Value on a Recurring Basis Classified Under the Appropriate Level of the Fair Value Hierarchy	The following table presents the Company’s assets and liabilities that are measured and recognized at fair value on a recurring basis classified under the appropriate level of the fair value hierarchy as of September 30, 2023, and December 31, 2022: Fair Value Measurements at (in thousands) Quoted Prices in Active Markets for Identical Assets and Liabilities Significant Other Observable Inputs Significant Unobservable Inputs Total Assets: Money market fund $ 14,928 $ — $ — $ 14,928 Total included in cash and cash equivalents 14,928 — — 14,928 Available for sale investments: Certificate of deposit — 9,181 — 9,181 Corporate debt securities — 22,368 — 22,368 Commercial paper — 7,613 — 7,613 U.S. government agencies — 6,821 — 6,821 U.S. treasury securities 20,147 — — 20,147 Total available for sale investments 20,147 45,983 — 66,130 Total assets measured at fair value on a recurring basis $ 35,075 $ 45,983 $ — $ 81,058 Fair Value Measurements at (in thousands) Quoted Prices in Active Markets for Identical Assets and Liabilities Significant Other Observable Inputs Significant Unobservable Inputs Total Assets: Money market fund $ 15,722 $ — $ — $ 15,722 Total included in cash and cash equivalents 15,722 — — 15,722 Available for sale investments: Certificate of deposit — 16,023 — 16,023 Corporate debt securities — 49,535 — 49,535 Commercial paper — 13,187 — 13,187 U.S. government agencies — 2,288 — 2,288 U.S. treasury securities 7,887 — — 7,887 Total available for sale investments 7,887 81,033 — 88,920 Total assets measured at fair value on a recurring basis $ 23,609 $ 81,033 $ — $ 104,642

Supplementary Balance Sheet I_2

Supplementary Balance Sheet Information (Tables)	9 Months Ended
	Sep. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Investments Available-for-sale	Investments available for sale consist of the following: As of September 30, 2023 (in thousands) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Market Value Maturity less than 1 year: Certificate of deposit $ 9,181 $ 3 $ (3) $ 9,181 Corporate debt securities 12,194 3 (28) 12,169 Commercial paper 7,616 — (3) 7,613 U.S. government agencies 6,852 — (31) 6,821 U.S. treasury securities 1,935 — (13) 1,922 Total maturity less than 1 year 37,778 6 (78) 37,706 Maturity 1 to 2 years: Corporate debt securities 10,281 3 (85) 10,199 U.S. treasury securities 18,478 — (253) 18,225 Total maturity 1 to 2 years 28,759 3 (338) 28,424 Total short-term investments $ 66,537 $ 9 $ (416) $ 66,130 As of December 31, 2022 (in thousands) Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Fair Market Value Maturity less than 1 year: Certificate of deposit $ 16,101 $ 3 $ (81) $ 16,023 Corporate debt securities 44,806 8 (275) 44,539 Commercial paper 13,203 4 (20) 13,187 Non U.S. government 2,284 4 — 2,288 U.S. treasury securities 7,905 — (18) 7,887 Total maturity less than 1 year 84,299 19 (394) 83,924 Maturity 1 to 2 years: Corporate debt securities 5,016 1 (21) 4,996 Total maturity 1 to 2 years 5,016 1 (21) 4,996 Total short-term investments $ 89,315 $ 20 $ (415) $ 88,920
Investments Available-for-sale in a Continuous Unrealized Loss Position	Investments available for sale that have been in a continuous unrealized loss position for greater than one-year consist of the following: As of September 30, 2023 (in thousands) Fair Market Value Gross Unrealized Loss Corporate debt securities $ 1,794 $ (10)
Schedule of Components of Property and Equipment	Property and equipment consist of the following: (in thousands) As of September 30, As of December 31, Furniture and office equipment $ 1,081 $ 1,066 Leasehold improvements 2,568 2,560 Laboratory equipment 1,332 1,056 4,981 4,682 Less—accumulated depreciation and amortization (3,664) (3,413) Property and equipment, net $ 1,317 $ 1,269
Schedule of Accrued Liabilities	Accrued liabilities consisted of the following: (in thousands) As of September 30, As of December 31, Accrued compensation $ 2,455 $ 1,849 Clinical trials 2,878 2,333 Research agreements and services 591 509 Director fees 125 125 Patent, license and other fees 33 24 Other accrued liabilities 69 337 Total accrued liabilities $ 6,151 $ 5,177

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	9 Months Ended
	Sep. 30, 2023
Stockholders' Equity Note [Abstract]
Schedule of Stock-Based Compensation Expense	Stock-based compensation expense related to Cardiff Oncology equity awards have been recognized in operating results as follows: Three Months Ended September 30, Nine Months Ended September 30, (in thousands) 2023 2022 2023 2022 Included in research and development expense $ 294 $ 286 $ 985 $ 746 Included in selling, general and administrative expense 661 751 2,615 2,498 Total stock-based compensation expense $ 955 $ 1,037 $ 3,600 $ 3,244
Schedule of Assumptions to Estimate Fair Value of Stock Option Awards	The estimated fair value of stock option awards was determined on the date of grant using the Black-Scholes option valuation model with the following weighted-average assumptions during the following periods indicated: Nine Months Ended September 30, 2023 2022 Risk-free interest rate 3.62 % 1.87 % Dividend yield 0 % 0 % Expected volatility of Cardiff Oncology common stock 109 % 106 % Expected term (1) 5.3 years 6.0 years
Summary of Stock Option Activity and of Changes in Stock Options Outstanding	A summary of stock option activity and changes in stock options outstanding is presented below: Total Options Weighted-Average Intrinsic Balance outstanding, December 31, 2022 5,069,458 $ 5.92 $ 19,322 Granted 2,138,624 $ 1.70 Forfeited and expired (555,655) $ 8.40 Balance outstanding, September 30, 2023 6,652,427 $ 4.36 $ 18,747 Exercisable at September 30, 2023 2,944,474 $ 5.88 $ 18,169 Vested and expected to vest at September 30, 2023 6,459,779 $ 4.42 $ 18,718
Summary of Warrant Activity and Changes in Warrants Outstanding	A summary of warrant activity and changes in warrants outstanding, including both liability and equity classifications is presented below: Total Warrants Weighted-Average Weighted-Average Balance outstanding, December 31, 2022 4,360,968 $ 5.33 2.1 years Expired (1,553,020) $ 10.54 Balance outstanding, September 30, 2023 2,807,948 $ 2.45 2.2 years

Organization and Basis of Pre_2

Organization and Basis of Presentation (Details) $ in Millions	Sep. 30, 2023 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Cash, cash equivalents and short-term investments	$ 81.4

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Antidilutive Securities (Details) - shares	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Net Loss Per Share
Antidilutive securities excluded from the calculation of basic and diluted loss per share (in shares)	9,461,252	10,934,858
Options to purchase Common Stock
Net Loss Per Share
Antidilutive securities excluded from the calculation of basic and diluted loss per share (in shares)	6,652,427	5,101,572
Warrants to purchase Common Stock
Net Loss Per Share
Antidilutive securities excluded from the calculation of basic and diluted loss per share (in shares)	2,807,948	4,490,159
Series A Convertible Preferred Stock
Net Loss Per Share
Antidilutive securities excluded from the calculation of basic and diluted loss per share (in shares)	877	877
Series E Convertible Preferred Stock
Net Loss Per Share
Antidilutive securities excluded from the calculation of basic and diluted loss per share (in shares)	0	1,342,250

Fair Value Measurements - Fair

Fair Value Measurements - Fair Value of Assets and Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Assets:
Total available for sale investments	$ 66,130	$ 88,920
Recurring basis
Assets:
Total included in cash and cash equivalents	14,928	15,722
Total available for sale investments	66,130	88,920
Total assets measured at fair value on a recurring basis	81,058	104,642
Recurring basis | Certificate of deposit
Assets:
Total available for sale investments	9,181	16,023
Recurring basis | Corporate debt securities
Assets:
Total available for sale investments	22,368	49,535
Recurring basis | Commercial paper
Assets:
Total available for sale investments	7,613	13,187
Recurring basis | Non U.S. government
Assets:
Total available for sale investments	6,821	2,288
Recurring basis | U.S. treasury securities
Assets:
Total available for sale investments	20,147	7,887
Recurring basis | Money market fund
Assets:
Total included in cash and cash equivalents	14,928	15,722
Recurring basis | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1)
Assets:
Total included in cash and cash equivalents	14,928	15,722
Total available for sale investments	20,147	7,887
Total assets measured at fair value on a recurring basis	35,075	23,609
Recurring basis | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1) | Certificate of deposit
Assets:
Total available for sale investments	0	0
Recurring basis | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1) | Corporate debt securities
Assets:
Total available for sale investments	0	0
Recurring basis | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1) | Commercial paper
Assets:
Total available for sale investments	0	0
Recurring basis | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1) | Non U.S. government
Assets:
Total available for sale investments	0	0
Recurring basis | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1) | U.S. treasury securities
Assets:
Total available for sale investments	20,147	7,887
Recurring basis | Quoted Prices in Active Markets for Identical Assets and Liabilities (Level 1) | Money market fund
Assets:
Total included in cash and cash equivalents	14,928	15,722
Recurring basis | Significant Other Observable Inputs (Level 2)
Assets:
Total included in cash and cash equivalents	0	0
Total available for sale investments	45,983	81,033
Total assets measured at fair value on a recurring basis	45,983	81,033
Recurring basis | Significant Other Observable Inputs (Level 2) | Certificate of deposit
Assets:
Total available for sale investments	9,181	16,023
Recurring basis | Significant Other Observable Inputs (Level 2) | Corporate debt securities
Assets:
Total available for sale investments	22,368	49,535
Recurring basis | Significant Other Observable Inputs (Level 2) | Commercial paper
Assets:
Total available for sale investments	7,613	13,187
Recurring basis | Significant Other Observable Inputs (Level 2) | Non U.S. government
Assets:
Total available for sale investments	6,821	2,288
Recurring basis | Significant Other Observable Inputs (Level 2) | U.S. treasury securities
Assets:
Total available for sale investments	0	0
Recurring basis | Significant Other Observable Inputs (Level 2) | Money market fund
Assets:
Total included in cash and cash equivalents	0	0
Recurring basis | Significant Unobservable Inputs (Level 3)
Assets:
Total included in cash and cash equivalents	0	0
Total available for sale investments	0	0
Total assets measured at fair value on a recurring basis	0	0
Recurring basis | Significant Unobservable Inputs (Level 3) | Certificate of deposit
Assets:
Total available for sale investments	0	0
Recurring basis | Significant Unobservable Inputs (Level 3) | Corporate debt securities
Assets:
Total available for sale investments	0	0
Recurring basis | Significant Unobservable Inputs (Level 3) | Commercial paper
Assets:
Total available for sale investments	0	0
Recurring basis | Significant Unobservable Inputs (Level 3) | Non U.S. government
Assets:
Total available for sale investments	0	0
Recurring basis | Significant Unobservable Inputs (Level 3) | U.S. treasury securities
Assets:
Total available for sale investments	0	0
Recurring basis | Significant Unobservable Inputs (Level 3) | Money market fund
Assets:
Total included in cash and cash equivalents	$ 0	$ 0

Supplementary Balance Sheet I_3

Supplementary Balance Sheet Information - Investments Available-for-sale (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Maturity less than 1 year:
Amortized Cost	$ 37,778	$ 84,299
Gross Unrealized Gains	6	19
Gross Unrealized Losses	(78)	(394)
Fair Market Value	37,706	83,924
Maturity 1 to 2 years:
Amortized Cost	28,759	5,016
Gross Unrealized Gains	3	1
Gross Unrealized Losses	(338)	(21)
Fair Market Value	28,424	4,996
Amortized Cost	66,537	89,315
Gross Unrealized Gains	9	20
Gross Unrealized Losses	(416)	(415)
Fair Market Value	66,130	88,920
Certificate of deposit
Maturity less than 1 year:
Amortized Cost	9,181	16,101
Gross Unrealized Gains	3	3
Gross Unrealized Losses	(3)	(81)
Fair Market Value	9,181	16,023
Corporate debt securities
Maturity less than 1 year:
Amortized Cost	12,194	44,806
Gross Unrealized Gains	3	8
Gross Unrealized Losses	(28)	(275)
Fair Market Value	12,169	44,539
Maturity 1 to 2 years:
Amortized Cost	10,281	5,016
Gross Unrealized Gains	3	1
Gross Unrealized Losses	(85)	(21)
Fair Market Value	10,199	4,996
Commercial paper
Maturity less than 1 year:
Amortized Cost	7,616	13,203
Gross Unrealized Gains	0	4
Gross Unrealized Losses	(3)	(20)
Fair Market Value	7,613	13,187
U.S. government agencies
Maturity less than 1 year:
Amortized Cost	6,852
Gross Unrealized Gains	0
Gross Unrealized Losses	(31)
Fair Market Value	6,821
Non U.S. government
Maturity less than 1 year:
Amortized Cost		2,284
Gross Unrealized Gains		4
Gross Unrealized Losses		0
Fair Market Value		2,288
U.S. treasury securities
Maturity less than 1 year:
Amortized Cost	1,935	7,905
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(13)	(18)
Fair Market Value	1,922	$ 7,887
Maturity 1 to 2 years:
Amortized Cost	18,478
Gross Unrealized Gains	0
Gross Unrealized Losses	(253)
Fair Market Value	$ 18,225

Supplementary Balance Sheet I_4

Supplementary Balance Sheet Information - Investments Available-for-sale in a Continuous Loss Position (Details) - Corporate debt securities $ in Thousands	Sep. 30, 2023 USD ($)
Debt Securities, Available-for-sale [Line Items]
Fair Market Value	$ 1,794
Gross Unrealized Loss	$ (10)

Supplementary Balance Sheet I_5

Supplementary Balance Sheet Information - Property and Equipment (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Property, equipment and depreciation and amortization
Property and equipment, gross	$ 4,981	$ 4,682
Less—accumulated depreciation and amortization	(3,664)	(3,413)
Property and equipment, net	1,317	1,269
Furniture and office equipment
Property, equipment and depreciation and amortization
Property and equipment, gross	1,081	1,066
Leasehold improvements
Property, equipment and depreciation and amortization
Property and equipment, gross	2,568	2,560
Laboratory equipment
Property, equipment and depreciation and amortization
Property and equipment, gross	$ 1,332	$ 1,056

Supplementary Balance Sheet I_6

Supplementary Balance Sheet Information - Accrued Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accrued compensation	$ 2,455	$ 1,849
Clinical trials	2,878	2,333
Research agreements and services	591	509
Director fees	125	125
Patent, license and other fees	33	24
Other accrued liabilities	69	337
Total accrued liabilities	$ 6,151	$ 5,177

Stockholders' Equity - Stock-ba

Stockholders' Equity - Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Stock-based compensation expense
Total stock based compensation expense	$ 955	$ 1,037	$ 3,600	$ 3,244
Options vested, fair value			4,000	4,000
Research and Development Expense
Stock-based compensation expense
Total stock based compensation expense	294	286	985	746
Selling, general and administrative expense
Stock-based compensation expense
Total stock based compensation expense	661	$ 751	2,615	$ 2,498
Options to purchase Common Stock
Stock-based compensation expense
Unrecognized compensation cost	$ 7,500		$ 7,500
Weighted-average remaining vesting period for recognition			2 years 3 months 18 days
Options outstanding, weighted average contractual life			8 years 1 month 6 days

Stockholders' Equity - Stock Op

Stockholders' Equity - Stock Option Activity (Details) - USD ($)	3 Months Ended	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022	Jun. 09, 2022
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures
Authorized shares under the plan (in shares)			3,150,000		5,150,000
Share-based payment arrangement, plan modification, incremental cost	$ 600,000
Options to purchase Common Stock
Weighted-average assumptions
Risk-free interest rate		3.62%	1.87%
Dividend yield (as a percent)		0%	0%
Expected volatility (as a percent)		109%	106%
Expected term(1)		5 years 3 months 18 days	6 years
Number of Options
Balance outstanding at the beginning of the period (in shares)		5,069,458
Granted (in shares)		2,138,624
Forfeited and expired (in shares)		(555,655)
Balance outstanding at the end of the period (in shares)	6,652,427	6,652,427
Exercisable at the end of the period (in shares)	2,944,474	2,944,474
Vested and expected to vest (in shares)	6,459,779	6,459,779
Weighted Average Exercise Price Per Share
Balance outstanding at the beginning of the period (in USD per share)		$ 5.92
Granted (in USD per share)		1.70
Forfeited and expired (in USD per share)		8.40
Balance outstanding at the end of the period (in USD per share)	$ 4.36	4.36
Exercisable at the end of the period (in USD per share)	5.88	5.88
Vested and expected to vest (in USD per share)	$ 4.42	$ 4.42
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures
Options outstanding, intrinsic value	$ 18,747	$ 18,747		$ 19,322
Exercisable at the end of the period, intrinsic value	18,169	18,169
Vested and expected to vest, intrinsic value	$ 18,718	$ 18,718
Inducement Grant Stock Options
Number of Options
Granted (in shares)	1,435,256
Equity Incentive Plan 2021
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures
Number of remaining shares available for issuance (in shares)	2,013,871	2,013,871

Stockholders' Equity - Warrants

Stockholders' Equity - Warrants (Details) - $ / shares	3 Months Ended	6 Months Ended	9 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Sep. 30, 2023
Number of Warrants
Balance of warrants outstanding at the end of the period (in shares)	2,807,948		2,807,948
Expired (in shares)	(1,553,020)
Balance of warrants outstanding at the beginning of the period (in shares)		4,360,968	4,360,968
Weighted Average Exercise Price Per Share
Weighted average exercise price of warrants at the beginning of the period (in USD per share)		$ 5.33	$ 5.33
Expired (in USD per share)	$ 10.54
Weighted average exercise price of warrants at the end of the period (in USD per share)	$ 2.45		$ 2.45
Term
Weighted-Average Remaining Contractual Term		2 years 1 month 6 days	2 years 2 months 12 days

Stockholders' Equity - Preferre

Stockholders' Equity - Preferred Stock (Details) - shares	Sep. 30, 2023	Aug. 08, 2023	Dec. 31, 2022
Class of Stock [Line Items]
Shares designated (in shares)	20,000,000		20,000,000
Series B Convertible Preferred Stock
Class of Stock [Line Items]
Shares designated (in shares)		8,860
Series C Convertible Preferred Stock
Class of Stock [Line Items]
Shares designated (in shares)		200,000
Series D Convertible Preferred Stock
Class of Stock [Line Items]
Shares designated (in shares)		154,670
Series E Convertible Preferred Stock
Class of Stock [Line Items]
Shares designated (in shares)		865,824

Commitments and Contingencies (

Commitments and Contingencies (Details) - USD ($) $ in Thousands	3 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Commitments and Contingencies Disclosure [Abstract]
Milestone and royalty payments made	$ 0	$ 0