Organization and Basis of Presentation	3 Months Ended
Mar. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Basis of Presentation	1. Organization and Basis of Presentation Viracta Therapeutics, Inc. (“Viracta,” the “Company,” or the “combined company”), formerly known as Sunesis Pharmaceuticals, Inc., was incorporated in the state of Delaware in February 1998 and is based in San Diego, California. Viracta is a precision oncology company, focused on the development of new medicines targeting virus-associated malignancies. Viracta’s lead product candidate is an all-oral combination therapy of its proprietary investigational drug, nanatinostat and the antiviral agent valganciclovir (collectively referred to as “Nana-val”). Nana-val is currently being investigated in multiple ongoing clinical trials, including NAVAL-1, a pivotal, global, multicenter, open-label Phase 2 basket trial for the treatment of multiple subtypes of relapsed/refractory (“R/R”) Epstein-Barr virus-positive (“EBV+”) lymphoma, as well as a multinational, open-label Phase 1b/2 trial for the treatment of EBV+ recurrent or metastatic nasopharyngeal carcinoma (“R/M NPC”) and other EBV+ solid tumors. The Company is also pursuing the application of its inducible synthetic lethality approach in other virus-related cancers. Merger Transaction between Private Viracta Therapeutics, Inc. and Sunesis Pharmaceuticals, Inc. and Name Change On November 29, 2020, the Company, then operating as Sunesis Pharmaceuticals, Inc., entered into an agreement and plan of merger and reorganization (the “Merger Agreement”) with privately-held Viracta Therapeutics, Inc. (“Private Viracta”) and Sol Merger Sub, Inc., a wholly-owned subsidiary of the Company (“Merger Sub”). On February 24, 2021, the transactions contemplated by the Merger Agreement were completed, and Merger Sub merged into Private Viracta, with Private Viracta surviving the merger as a wholly owned subsidiary of the Company (the “Merger”). Sunesis changed its name to Viracta Therapeutics, Inc. On February 25, 2021, the combined company’s common stock began trading on The Nasdaq Global Select Market under the ticker symbol “VIRX”. Except as otherwise indicated, references herein to “Viracta,” the “Company,” or the “combined company”, refer to Viracta Therapeutics, Inc. on a post-Merger basis, and the term “Private Viracta” refers to the business of privately-held Viracta Therapeutics, Inc., prior to the completion of the Merger. References to “Sunesis” refer to Sunesis Pharmaceuticals, Inc. prior to completion of the Merger. Pursuant to the terms of the Merger Agreement, each outstanding share of Private Viracta common stock outstanding immediately prior to the closing of the Merger was converted into approximately 0.1119 shares of Company common stock (the “Exchange Ratio”), after taking into account the Reverse Stock Split, as defined below. Immediately prior to the closing of the Merger, all shares of Private Viracta preferred stock then outstanding were exchanged into shares of common stock of Private Viracta. In addition, all outstanding options exercisable for common stock of Private Viracta and warrants exercisable for capital stock of Private Viracta became options and warrants exercisable for the same number of shares of common stock of the Company multiplied by the Exchange Ratio at an exercise price equal to the pre-Merger price divided by the Exchange Ratio. Immediately following the Merger, stockholders of Private Viracta owned approximately 86% of the outstanding common stock of the combined company. This transaction was accounted for as a reverse asset acquisition in accordance with generally accepted accounting principles in the United States of America (“GAAP”), as Viracta was considered to be acquiring Sunesis and the Merger was accounted for as an asset acquisition, even though Sunesis was the legal acquirer and the issuer of the common stock in the Merger. This determination was primarily based on the facts that, immediately following the Merger: (i) Private Viracta’s stockholders owned a substantial majority of the voting rights in the combined company, (ii) Private Viracta designated a majority of the members of the initial board of directors of the combined company, and (iii) Private Viracta’s senior management holds all key positions in the senior management of the combined company. As a result, as of the closing date of the Merger, the net assets of Sunesis were recorded at their acquisition-date relative fair values in the accompanying condensed consolidated financial statements of the Company and the reported operating results prior to the Merger are those of Private Viracta. To determine the accounting for this transaction under GAAP, a company must assess whether an integrated set of assets and activities should be accounted for as an acquisition of a business or an asset acquisition. The guidance required an initial screen test to determine if substantially all of the fair value of the gross assets acquired was concentrated in a single asset or group of similar assets. The initial screen test was not met as there was no single asset or group of similar assets for Sunesis that represented a significant majority in this acquisition. However, at the time of the closing of the Merger, Sunesis did not have processes or an organized workforce that significantly contributed to its ability to create outputs, and substantially all of its fair value was concentrated in cash, working capital, and in-process research and development (“IPR&D”). As such, the acquisition was treated as an asset acquisition. Concurrent with the execution of the Merger Agreement, Private Viracta entered into an agreement for the sale of common stock in a private placement, which was completed immediately prior to the close of the Merger and resulted in gross proceeds of $65.0 million. In connection with the closing of the Merger and the concurrent private placement of common stock, the holders of the Company’s preferred stock waived their right to exchange their shares into any class of the Company’s stock other than common stock. On February 24, 2021, in connection with, and prior to the completion of, the Merger, the Company effected a 3.5-for-one reverse stock split of its then outstanding common stock (the “Reverse Stock Split”). The par value and the authorized shares of the common stock were not adjusted as a result of the Reverse Stock Split. Unless otherwise noted herein, references to share and per-share amounts give retroactive effect to the Reverse Stock Split and the Exchange Ratio which was effected upon the Merger. Liquidity and Risks As of March 31, 2022, the Company has devoted substantially all of its efforts to product development and has not realized product sales revenues from its planned principal operations. The Company has a limited operating history, and the sales and income potential of the Company’s business and market are unproven. The Company has experienced net losses since its inception and, as of March 31, 2022, had an accumulated deficit of $176.2 million. The Company expects to continue to incur net losses for at least the next several years. A successful transition to attaining profitable operations is dependent upon achieving a level of revenues adequate to support the Company’s cost structure. If the Company is unable to generate revenues adequate to support its cost structure, the Company will need to raise additional capital through the issuance of its common stock, through other equity or debt financings or through collaborations or partnerships with other companies. As of March 31, 2022, the Company had cash and cash equivalents of $92.2 million and working capital of $87.6 million. On November 4, 2021, the Company entered into a loan and security agreement with Silicon Valley Bank (“SVB”) and Oxford Finance LLC (“Oxford”), collectively referred to as “Lenders,” for up to $50.0 million, with $5.0 million refinanced at the time of entering into the agreement and $45.0 million available under certain circumstances. The second tranche of $20.0 million would be available upon request by the Company and Lenders approval until August 31, 2022, and the third tranche, $25.0 million, would be available at the Company's request subject to Lenders' discretion. As of March 31, 2022, neither tranche had been requested. Based on the Company’s current financial position and business plan, management believes that its existing cash and cash equivalents will be sufficient to fund the Company’s planned operations for at least twelve months from the issuance date of these condensed consolidated financial statements. The COVID-19 pandemic has caused significant business disruption around the globe. The effects of the COVID-19 pandemic continue to rapidly evolve, and the full impact of the COVID-19 pandemic remains highly uncertain and subject to change. The Company has taken certain measures and continues to evaluate other potential measures to mitigate the impact of the COVID-19 pandemic on our clinical trials. The Company does not yet know the full extent of potential delays or impacts on our business, our clinical trials, healthcare systems or the global economy as a whole. These effects could have a material impact on our operations, including the timing and ability of the Company to complete certain clinical trials and other efforts required to advance the development of its product candidates and raise additional capital.

Organization and Basis of Presentation

3 Months Ended

Mar. 31, 2022

Organization, Consolidation and Presentation of Financial Statements [Abstract]

1. Organization and Basis of Presentation

Viracta Therapeutics, Inc. (“Viracta,” the “Company,” or the “combined company”), formerly known as Sunesis Pharmaceuticals, Inc., was incorporated in the state of Delaware in February 1998 and is based in San Diego, California. Viracta is a precision oncology company, focused on the development of new medicines targeting virus-associated malignancies. Viracta’s lead product candidate is an all-oral combination therapy of its proprietary investigational drug, nanatinostat and the antiviral agent valganciclovir (collectively referred to as “Nana-val”). Nana-val is currently being investigated in multiple ongoing clinical trials, including NAVAL-1, a pivotal, global, multicenter, open-label Phase 2 basket trial for the treatment of multiple subtypes of relapsed/refractory (“R/R”) Epstein-Barr virus-positive (“EBV+”) lymphoma, as well as a multinational, open-label Phase 1b/2 trial for the treatment of EBV+ recurrent or metastatic nasopharyngeal carcinoma (“R/M NPC”) and other EBV+ solid tumors. The Company is also pursuing the application of its inducible synthetic lethality approach in other virus-related cancers.

Merger Transaction between Private Viracta Therapeutics, Inc. and Sunesis Pharmaceuticals, Inc. and Name Change

On November 29, 2020, the Company, then operating as Sunesis Pharmaceuticals, Inc., entered into an agreement and plan of merger and reorganization (the “Merger Agreement”) with privately-held Viracta Therapeutics, Inc. (“Private Viracta”) and Sol Merger Sub, Inc., a wholly-owned subsidiary of the Company (“Merger Sub”). On February 24, 2021, the transactions contemplated by the Merger Agreement were completed, and Merger Sub merged into Private Viracta, with Private Viracta surviving the merger as a wholly owned subsidiary of the Company (the “Merger”). Sunesis changed its name to Viracta Therapeutics, Inc. On February 25, 2021, the combined company’s common stock began trading on The Nasdaq Global Select Market under the ticker symbol “VIRX”.

Except as otherwise indicated, references herein to “Viracta,” the “Company,” or the “combined company”, refer to Viracta Therapeutics, Inc. on a post-Merger basis, and the term “Private Viracta” refers to the business of privately-held Viracta Therapeutics, Inc., prior to the completion of the Merger. References to “Sunesis” refer to Sunesis Pharmaceuticals, Inc. prior to completion of the Merger.

Pursuant to the terms of the Merger Agreement, each outstanding share of Private Viracta common stock outstanding immediately prior to the closing of the Merger was converted into approximately 0.1119 shares of Company common stock (the “Exchange Ratio”), after taking into account the Reverse Stock Split, as defined below. Immediately prior to the closing of the Merger, all shares of Private Viracta preferred stock then outstanding were exchanged into shares of common stock of Private Viracta. In addition, all outstanding options exercisable for common stock of Private Viracta and warrants exercisable for capital stock of Private Viracta became options and warrants exercisable for the same number of shares of common stock of the Company multiplied by the Exchange Ratio at an exercise price equal to the pre-Merger price divided by the Exchange Ratio. Immediately following the Merger, stockholders of Private Viracta owned approximately 86% of the outstanding common stock of the combined company.

This transaction was accounted for as a reverse asset acquisition in accordance with generally accepted accounting principles in the United States of America (“GAAP”), as Viracta was considered to be acquiring Sunesis and the Merger was accounted for as an asset acquisition, even though Sunesis was the legal acquirer and the issuer of the common stock in the Merger. This determination was primarily based on the facts that, immediately following the Merger: (i) Private Viracta’s stockholders owned a substantial majority of the voting rights in the combined company, (ii) Private Viracta designated a majority of the members of the initial board of directors of the combined company, and (iii) Private Viracta’s senior management holds all key positions in the senior management of the combined company. As a result, as of the closing date of the Merger, the net assets of Sunesis were recorded at their acquisition-date relative fair values in the accompanying condensed consolidated financial statements of the Company and the reported operating results prior to the Merger are those of Private Viracta.

To determine the accounting for this transaction under GAAP, a company must assess whether an integrated set of assets and activities should be accounted for as an acquisition of a business or an asset acquisition. The guidance required an initial screen test to determine if substantially all of the fair value of the gross assets acquired was concentrated in a single asset or group of similar assets. The initial screen test was not met as there was no single asset or group of similar assets for Sunesis that represented a significant majority in this acquisition. However, at the time of the closing of the Merger, Sunesis did not have processes or an organized workforce that significantly contributed to its ability to create outputs, and substantially all of its fair value was concentrated in cash, working capital, and in-process research and development (“IPR&D”). As such, the acquisition was treated as an asset acquisition.

Concurrent with the execution of the Merger Agreement, Private Viracta entered into an agreement for the sale of common stock in a private placement, which was completed immediately prior to the close of the Merger and resulted in gross proceeds of $65.0 million.

In connection with the closing of the Merger and the concurrent private placement of common stock, the holders of the Company’s preferred stock waived their right to exchange their shares into any class of the Company’s stock other than common stock.

On February 24, 2021, in connection with, and prior to the completion of, the Merger, the Company effected a 3.5-for-one reverse stock split of its then outstanding common stock (the “Reverse Stock Split”). The par value and the authorized shares of the common stock were not adjusted as a result of the Reverse Stock Split. Unless otherwise noted herein, references to share and per-share amounts give retroactive effect to the Reverse Stock Split and the Exchange Ratio which was effected upon the Merger.

Liquidity and Risks

As of March 31, 2022, the Company has devoted substantially all of its efforts to product development and has not realized product sales revenues from its planned principal operations. The Company has a limited operating history, and the sales and income potential of the Company’s business and market are unproven. The Company has experienced net losses since its inception and, as of March 31, 2022, had an accumulated deficit of $176.2 million. The Company expects to continue to incur net losses for at least the next several years. A successful transition to attaining profitable operations is dependent upon achieving a level of revenues adequate to support the Company’s cost structure. If the Company is unable to generate revenues adequate to support its cost structure, the Company will need to raise additional capital through the issuance of its common stock, through other equity or debt financings or through collaborations or partnerships with other companies. As of March 31, 2022, the Company had cash and cash equivalents of $92.2 million and working capital of $87.6 million.

On November 4, 2021, the Company entered into a loan and security agreement with Silicon Valley Bank (“SVB”) and Oxford Finance LLC (“Oxford”), collectively referred to as “Lenders,” for up to $50.0 million, with $5.0 million refinanced at the time of entering into the agreement and $45.0 million available under certain circumstances. The second tranche of $20.0 million would be available upon request by the Company and Lenders approval until August 31, 2022, and the third tranche, $25.0 million, would be available at the Company's request subject to Lenders' discretion. As of March 31, 2022, neither tranche had been requested.

Based on the Company’s current financial position and business plan, management believes that its existing cash and cash equivalents will be sufficient to fund the Company’s planned operations for at least twelve months from the issuance date of these condensed consolidated financial statements.

The COVID-19 pandemic has caused significant business disruption around the globe. The effects of the COVID-19 pandemic continue to rapidly evolve, and the full impact of the COVID-19 pandemic remains highly uncertain and subject to change. The Company has taken certain measures and continues to evaluate other potential measures to mitigate the impact of the COVID-19 pandemic on our clinical trials. The Company does not yet know the full extent of potential delays or impacts on our business, our clinical trials, healthcare systems or the global economy as a whole. These effects could have a material impact on our operations, including the timing and ability of the Company to complete certain clinical trials and other efforts required to advance the development of its product candidates and raise additional capital.