Description of Business and Basis of Presentation (Policies)	6 Months Ended
Jun. 30, 2022
Accounting Policies [Abstract]
Liquidity and Financial Condition	Liquidity and Financial Condition The Company follows Accounting Standards Codification (ASC) Topic 205-40, Presentation of Financial Statements—Going Concern, which requires that management perform a two-step analysis over its ability to continue as a going concern. Management must first evaluate whether there are conditions and events that raise substantial doubt about the Company’s ability to continue as a going concern and to meet its obligations as they become due within one year after the date that the financial statements are issued (step 1). If management concludes that substantial doubt is raised, management is also required to consider whether its plans alleviate that doubt (step 2). The Company has incurred operating losses and negative cash flows from operating activities since inception. As of June 30, 2022, the Company had cash, cash equivalents and short-term investments of $53.1 million, outstanding debt of $16.1 million and an accumulated deficit of $582.4 million. Management concluded that the balance of cash and cash equivalents may not be sufficient to fund the Company’s planned expenditures and meet its obligations for the twelve months following the financial statement issuance date without raising additional funding or making changes to operating plans or programs to reduce expenses. As a result, there is substantial doubt about the Company’s ability to continue as a going concern for twelve months following the issuance date of the condensed financial statements as of and for the three and six months ended June 30, 2022. The Company’s ability to continue as a going concern is dependent upon its ability to obtain additional funding or adjust operating plans or programs and associated spending. Management believes that the Company’s liquidity position provides sufficient runway to achieve critical near term research and development milestones. Management intends to raise additional funding through future debt and/or equity financings or other sources, such as potential collaboration agreements. But, additional capital may not be available in sufficient amounts or on reasonable terms, if at all. If the Company is not able to secure adequate additional funding, the Company may be forced to make reductions in spending, extend payment terms with suppliers, liquidate assets where possible, and/or suspend or curtail planned programs. Any of these actions could materially harm the Company’s business, results of operations, and future prospects. The condensed financial statements have been prepared assuming the Company will continue as a going concern and do not include any adjustments that might result from the outcome of this uncertainty.
Basis of Presentation	Basis of Presentation The accompanying interim condensed financial statements are unaudited. These unaudited interim condensed financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (GAAP) and following the requirements of the United States Securities and Exchange Commission (SEC) for interim reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by GAAP can be condensed or omitted. In the Company’s opinion, the unaudited interim condensed financial statements have been prepared on the same basis as the audited financial statements and include all adjustments, which include only normal recurring adjustments necessary for the fair presentation of the Company’s financial position, results of operations and cash flows for the periods presented. These condensed financial statements do not include all disclosures required by GAAP and should be read in conjunction with the Company’s audited financial statements and accompanying notes for the year ended December 31, 2021 included in the Company’s Annual Report on Form 10-K, as filed with the SEC on February 28, 2022. The results presented in these unaudited condensed financial statements are not necessarily indicative of the results expected for the full fiscal year or any other interim period or any future year or period.
Use of Estimates	Use of Estimates The condensed financial statements have been prepared in accordance with GAAP. The preparation of financial statements in conformity with GAAP requires the Company to 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 amounts of product sales and expense during the reporting period. Although these estimates are based on the Company’s knowledge of current events and anticipated actions it may undertake in the future, actual results may ultimately materially differ from these estimates and assumptions.
Short-Term Investments	Short-term Investments From time to time, the Company carries short-term investments classified as available-for-sale debt securities at fair value as determined by prices for identical or similar securities at the balance sheet date. Short-term investments consist of both Level 1 financial instruments in the fair value hierarchy (see Note 6 – Fair Value). Realized gains or losses of available-for-sale securities are determined using the specific identification method and net realized gains and losses are included in interest income. The Company periodically reviews available-for-sale securities for other-than-temporary declines in fair value below the cost basis, and whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. The Company records unrealized gains and losses on available-for-sale debt securities as a component of other comprehensive loss within the condensed statements of comprehensive loss and as a separate component of stockholders’ equity on the condensed balance sheets. The Company does not hold equity securities in its investment portfolio.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The Company’s financial instruments include cash, cash equivalents, short-term investments, prepaid expenses and other assets, accounts payable, accrued expenses, accrued compensation and long-term debt. The carrying value of the Company’s cash and cash equivalents, short-term investments, prepaid expenses and other current assets, other long-term assets, accounts payable, accrued expenses, and accrued compensation approximate fair value due to the short-term nature of these items. Based on Level 3 inputs and the borrowing rates currently available for loans with similar terms, the Company believes the fair value of long-term debt approximates its carrying value.
Risks and Uncertainties Related to COVID-19	Risks and Uncertainties Related to COVID-19 In March 2020, the World Health Organization declared COVID-19 a global pandemic. The COVID-19 pandemic could pose significant risks to the Company’s business; however, the ultimate impact of the pandemic is highly uncertain. Given the unprecedented and evolving nature of the COVID-19 pandemic, including the rise of new variants, there continues to be significant uncertainty about the progression and ultimate impact of the pandemic on the Company’s operations. The Company has taken steps to mitigate the impact of the COVID-19 pandemic on its clinical trials, including developing processes to ensure the integrity of data collection from enrolled patients and supporting sites’ ability to enroll patients, among other activities. Nonetheless the Company does not know the full extent of potential future delays or impacts on its business operations, its preclinical programs and clinical trials, healthcare systems, its financial condition, or the global economy as a whole resulting from the COVID-19 pandemic. In addition, as a result of the COVID-19 pandemic, the Company has taken steps to protect the health and safety of its employees and community by following directives from the State of California and the applicable local governments, and guidance from the U.S. Centers for Disease Control and Prevention (CDC). Various safety protocols have been implemented and the Company is currently allowing employees who can remotely perform their essential functions to work from home.
Recent Accounting Pronouncements	Recent Accounting Pronouncements Not Yet Adopted In June 2016, Accounting Standards Update (ASU) No. 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (ASU 2016-13) was issued, as amended. ASU 2016-13 introduces the current expected credit loss model, which will require an entity to measure credit losses for certain financial instruments and financial assets. ASU 2016-13 will also apply to receivables arising from revenue transactions such as accounts receivable. ASU 2016-13 is effective for the Company beginning January 1, 2023. The Company does not expect the adoption of ASU 2016-13 to have a material effect on its financial position, results of operations or cash flows.

Description of Business and Basis of Presentation (Policies)

6 Months Ended

Jun. 30, 2022

The Company follows Accounting Standards Codification (ASC) Topic 205-40, Presentation of Financial Statements—Going Concern, which requires that management perform a two-step analysis over its ability to continue as a going concern. Management must first evaluate whether there are conditions and events that raise substantial doubt about the Company’s ability to continue as a going concern and to meet its obligations as they become due within one year after the date that the financial statements are issued (step 1). If management concludes that substantial doubt is raised, management is also required to consider whether its plans alleviate that doubt (step 2).

The Company has incurred operating losses and negative cash flows from operating activities since inception. As of June 30, 2022, the Company had cash, cash equivalents and short-term investments of $53.1 million, outstanding debt of $16.1 million and an accumulated deficit of $582.4 million. Management concluded that the balance of cash and cash equivalents may not be sufficient to fund the Company’s planned expenditures and meet its obligations for the twelve months following the financial statement issuance date without raising additional funding or making changes to operating plans or programs to reduce expenses. As a result, there is substantial doubt about the Company’s ability to continue as a going concern for twelve months following the issuance date of the condensed financial statements as of and for the three and six months ended June 30, 2022. The Company’s ability to continue as a going concern is dependent upon its ability to obtain additional funding or adjust operating plans or programs and associated spending. Management believes that the Company’s liquidity position provides sufficient runway to achieve critical near term research and development milestones. Management intends to raise additional funding through future debt and/or equity financings or other sources, such as potential collaboration agreements. But, additional capital may not be available in sufficient amounts or on reasonable terms, if at all. If the Company is not able to secure adequate additional funding, the Company may be forced to make reductions in spending, extend payment terms with suppliers, liquidate assets where possible, and/or suspend or curtail planned programs. Any of these actions could materially harm the Company’s business, results of operations, and future prospects. The condensed financial statements have been prepared assuming the Company will continue as a going concern and do not include any adjustments that might result from the outcome of this uncertainty.

Basis of Presentation

The accompanying interim condensed financial statements are unaudited. These unaudited interim condensed financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (GAAP) and following the requirements of the United States Securities and Exchange Commission (SEC) for interim reporting. As permitted under those rules, certain footnotes or other financial information that are normally required by GAAP can be condensed or omitted. In the Company’s opinion, the unaudited interim condensed financial statements have been prepared on the same basis as the audited financial statements and include all adjustments, which include only normal recurring adjustments necessary for the fair presentation of the Company’s financial position, results of operations and cash flows for the periods presented. These condensed financial statements do not include all disclosures required by GAAP and should be read in conjunction with the Company’s audited financial statements and accompanying notes for the year ended December 31, 2021 included in the Company’s Annual Report on Form 10-K, as filed with the SEC on February 28, 2022. The results presented in these unaudited condensed financial statements are not necessarily indicative of the results expected for the full fiscal year or any other interim period or any future year or period.

Use of Estimates

The condensed financial statements have been prepared in accordance with GAAP. The preparation of financial statements in conformity with GAAP requires the Company to 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 amounts of product

sales and expense during the reporting period. Although these estimates are based on the Company’s knowledge of current events and anticipated actions it may undertake in the future, actual results may ultimately materially differ from these estimates and assumptions.

Short-Term Investments

Short-term Investments

From time to time, the Company carries short-term investments classified as available-for-sale debt securities at fair value as determined by prices for identical or similar securities at the balance sheet date. Short-term investments consist of both Level 1 financial instruments in the fair value hierarchy (see Note 6 – Fair Value).

Realized gains or losses of available-for-sale securities are determined using the specific identification method and net realized gains and losses are included in interest income. The Company periodically reviews available-for-sale securities for other-than-temporary declines in fair value below the cost basis, and whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. The Company records unrealized gains and losses on available-for-sale debt securities as a component of other comprehensive loss within the condensed statements of comprehensive loss and as a separate component of stockholders’ equity on the condensed balance sheets. The Company does not hold equity securities in its investment portfolio.

Fair Value of Financial Instruments

The Company’s financial instruments include cash, cash equivalents, short-term investments, prepaid expenses and other assets, accounts payable, accrued expenses, accrued compensation and long-term debt. The carrying value of the Company’s cash and cash equivalents, short-term investments, prepaid expenses and other current assets, other long-term assets, accounts payable, accrued expenses, and accrued compensation approximate fair value due to the short-term nature of these items. Based on Level 3 inputs and the borrowing rates currently available for loans with similar terms, the Company believes the fair value of long-term debt approximates its carrying value.

Risks and Uncertainties Related to COVID-19

In March 2020, the World Health Organization declared COVID-19 a global pandemic. The COVID-19 pandemic could pose significant risks to the Company’s business; however, the ultimate impact of the pandemic is highly uncertain.

Given the unprecedented and evolving nature of the COVID-19 pandemic, including the rise of new variants, there continues to be significant uncertainty about the progression and ultimate impact of the pandemic on the Company’s operations. The Company has taken steps to mitigate the impact of the COVID-19 pandemic on its clinical trials, including developing processes to ensure the integrity of data collection from enrolled patients and supporting sites’ ability to enroll patients, among other activities. Nonetheless the Company does not know the full extent of potential future delays or impacts on its business operations, its preclinical programs and clinical trials, healthcare systems, its financial condition, or the global economy as a whole resulting from the COVID-19 pandemic.

In addition, as a result of the COVID-19 pandemic, the Company has taken steps to protect the health and safety of its employees and community by following directives from the State of California and the applicable local governments, and guidance from the U.S. Centers for Disease Control and Prevention (CDC). Various safety protocols have been implemented and the Company is currently allowing employees who can remotely perform their essential functions to work from home.

Recent Accounting Pronouncements

Not Yet Adopted

In June 2016, Accounting Standards Update (ASU) No. 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (ASU 2016-13) was issued, as amended. ASU 2016-13 introduces the current expected credit loss model, which will require an entity to measure credit losses for certain financial instruments and financial assets. ASU 2016-13 will also apply to receivables arising from revenue transactions such as accounts receivable. ASU 2016-13 is effective for the Company beginning January 1, 2023. The Company does not expect the adoption of ASU 2016-13 to have a material effect on its financial position, results of operations or cash flows.