Company Overview	3 Months Ended
Mar. 31, 2019
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Company Overview	1. Company Overview Description of Business Sunesis Pharmaceuticals, Inc. (“Sunesis” or the “Company”) is a biopharmaceutical company focused on the development of new targeted inhibitors for the treatment of solid and hematologic cancers. The Company’s primary activities since incorporation have been conducting research and development internally and through corporate collaborators, in-licensing and out-licensing pharmaceutical compounds and technology, conducting clinical trials, and raising capital. The Company’s lead program is vecabrutinib, a selective non-covalent inhibitor of Bruton’s Tyrosine Kinase (“BTK”) with activity against both wild type and C481S-mutated BTK, the most common mutation associated with resistance to ibrutinib. Vecabrutinib is being studied in a Phase 1b/2 clinical trial to assess safety and activity in patients with advanced B-cell malignancies after two or more prior therapies, including ibrutinib or another covalent BTK inhibitor where approved for the disease. The Phase 1b portion of the study is a dose escalation component that will proceed to define a maximum tolerated dose and/or a recommended Phase 2 dose. Upon identifying the Phase 2 dose, the Phase 2 portion will further explore clinical activity and safety in disease- and mutation-specific cohorts, including patients with and without BTK C481 mutations. The Company is also developing SNS-510, a PDK1 inhibitor licensed from Millennium Pharmaceuticals, Inc., a wholly-owned subsidiary of Takeda Pharmaceutical Company Limited (“Takeda”). The Company acquired from Takeda global commercial rights to several potential first-in class, preclinical inhibitors of the novel target PDK1, including SNS-510. The Company is currently characterizing SNS-510 through preclinical pharmacology studies, manufacturing and formulation activities. The Company is in a collaboration with Takeda for the development of TAK-580 (formerly MLN2480), an oral pan-RAF inhibitor, which is under investigation for pediatric low-grade glioma. Liquidity and Going Concern The Company has incurred significant losses and negative cash flows from operations since its inception, and as of March 31, 2019, the Company had cash and cash equivalents totaling $24.8 million and an accumulated deficit of $665.3 million. The Company expects to continue to incur significant losses for the foreseeable future as it continues development of its kinase inhibitor pipeline, including its BTK inhibitor, vecabrutinib. The Company has prioritized development funding on its kinase inhibitor portfolio with a focus on vecabrutinib. The Company has a limited number of products that are still in the early stages of development and will require significant additional future investment. The Company’s cash and cash equivalents are not sufficient to support its operations for a period of twelve months from the date these condensed consolidated financial statements are available to be issued. These factors raise substantial doubt about its ability to continue as a going concern. The Company will require additional financing to fund working capital, repay debt and pay its obligations as they come due. Additional financing might include one or more offerings and one or more of a combination of equity securities, debt arrangements or partnership or licensing collaborations. However, there can be no assurance that the Company will be successful in acquiring additional funding at levels sufficient to fund its operations or on terms favorable to the Company. If the Company is unsuccessful in its efforts to raise additional financing in the near term, the Company will be required to significantly reduce or cease operations. The principal payments due under the Loan Agreement (as defined in Note 6) have been classified as a current liability as of March 31, 2019 and December 31, 2018 due to the considerations discussed above and the assessment that the material adverse change clause under the Loan Agreement is not within the Company's control. In April 2019, the Company used the proceeds of the SVB Loan Agreement (as defined in Note 10) plus cash on hand to repay its remaining obligations in the amount of $5.9 million under Loan Agreement and Amendments (as defined in Note 6). The SVB Loan Agreement also contains customary events of default, including among other things, the Company’s failure to make any principal or interest payments when due, the occurrence of certain bankruptcy or insolvency events or its breach of the covenants under the SVB Loan Agreement. Upon the occurrence of an event of default, SVB (as defined in Note 10) may, among other things, accelerate the Company’s obligations under the SVB Loan Agreement. The Company has not been notified of an event of default by SVB as of the date of the filing of this Form 10-Q. The accompanying condensed consolidated financial statements have been prepared assuming the Company will continue to operate as a going concern, which contemplates the realization of assets and the settlement of liabilities in the normal course of business. The condensed consolidated financial statements do not include any adjustments to reflect the possible future effects on the recoverability and classification of assets or the amounts of liabilities that may result from uncertainty related to the Company’s ability to continue as a going concern. Concentrations of Credit Risk Financial instruments that potentially subject the Company to concentrations of credit risk generally consist of cash and cash equivalents. The Company is exposed to credit risk in the event of default by the institutions holding its cash, cash equivalents and any marketable securities to the extent of the amounts recorded in the condensed consolidated balance sheets.

Company Overview

3 Months Ended

Mar. 31, 2019

Organization Consolidation And Presentation Of Financial Statements [Abstract]

1. Company Overview

Description of Business

Sunesis Pharmaceuticals, Inc. (“Sunesis” or the “Company”) is a biopharmaceutical company focused on the development of new targeted inhibitors for the treatment of solid and hematologic cancers. The Company’s primary activities since incorporation have been conducting research and development internally and through corporate collaborators, in-licensing and out-licensing pharmaceutical compounds and technology, conducting clinical trials, and raising capital.

The Company’s lead program is vecabrutinib, a selective non-covalent inhibitor of Bruton’s Tyrosine Kinase (“BTK”) with activity against both wild type and C481S-mutated BTK, the most common mutation associated with resistance to ibrutinib. Vecabrutinib is being studied in a Phase 1b/2 clinical trial to assess safety and activity in patients with advanced B-cell malignancies after two or more prior therapies, including ibrutinib or another covalent BTK inhibitor where approved for the disease. The Phase 1b portion of the study is a dose escalation component that will proceed to define a maximum tolerated dose and/or a recommended Phase 2 dose. Upon identifying the Phase 2 dose, the Phase 2 portion will further explore clinical activity and safety in disease- and mutation-specific cohorts, including patients with and without BTK C481 mutations.

The Company is also developing SNS-510, a PDK1 inhibitor licensed from Millennium Pharmaceuticals, Inc., a wholly-owned subsidiary of Takeda Pharmaceutical Company Limited (“Takeda”). The Company acquired from Takeda global commercial rights to several potential first-in class, preclinical inhibitors of the novel target PDK1, including SNS-510. The Company is currently characterizing SNS-510 through preclinical pharmacology studies, manufacturing and formulation activities.

The Company is in a collaboration with Takeda for the development of TAK-580 (formerly MLN2480), an oral pan-RAF inhibitor, which is under investigation for pediatric low-grade glioma.

Liquidity and Going Concern

The Company has incurred significant losses and negative cash flows from operations since its inception, and as of March 31, 2019, the Company had cash and cash equivalents totaling $24.8 million and an accumulated deficit of $665.3 million.

The Company expects to continue to incur significant losses for the foreseeable future as it continues development of its kinase inhibitor pipeline, including its BTK inhibitor, vecabrutinib. The Company has prioritized development funding on its kinase inhibitor portfolio with a focus on vecabrutinib. The Company has a limited number of products that are still in the early stages of development and will require significant additional future investment.

The Company’s cash and cash equivalents are not sufficient to support its operations for a period of twelve months from the date these condensed consolidated financial statements are available to be issued. These factors raise substantial doubt about its ability to continue as a going concern. The Company will require additional financing to fund working capital, repay debt and pay its obligations as they come due. Additional financing might include one or more offerings and one or more of a combination of equity securities, debt arrangements or partnership or licensing collaborations. However, there can be no assurance that the Company will be successful in acquiring additional funding at levels sufficient to fund its operations or on terms favorable to the Company. If the Company is unsuccessful in its efforts to raise additional financing in the near term, the Company will be required to significantly reduce or cease operations. The principal payments due under the Loan Agreement (as defined in Note 6) have been classified as a current liability as of March 31, 2019 and December 31, 2018 due to the considerations discussed above and the assessment that the material adverse change clause under the Loan Agreement is not within the Company's control. In April 2019, the Company used the proceeds of the SVB Loan Agreement (as defined in Note 10) plus cash on hand to repay its remaining obligations in the amount of $5.9 million under Loan Agreement and Amendments (as defined in Note 6). The SVB Loan Agreement also contains customary events of default, including among other things, the Company’s failure to make any principal or interest payments when due, the occurrence of certain bankruptcy or insolvency events or its breach of the covenants under the SVB Loan Agreement. Upon the occurrence of an event of default, SVB (as defined in Note 10) may, among other things, accelerate the Company’s obligations under the SVB Loan Agreement. The Company has not been notified of an event of default by SVB as of the date of the filing of this Form 10-Q. The accompanying condensed consolidated financial statements have been prepared assuming the Company will continue to operate as a going concern, which contemplates the realization of assets and the settlement of liabilities in the normal course of business. The condensed consolidated financial statements do not include any adjustments to reflect the possible future effects on the recoverability and classification of assets or the amounts of liabilities that may result from uncertainty related to the Company’s ability to continue as a going concern.

Concentrations of Credit Risk

Financial instruments that potentially subject the Company to concentrations of credit risk generally consist of cash and cash equivalents. The Company is exposed to credit risk in the event of default by the institutions holding its cash, cash equivalents and any marketable securities to the extent of the amounts recorded in the condensed consolidated balance sheets.