UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Form 10-Q (Mark One) Delaware 47-4859534 (State or Other Jurisdiction of Incorporation or Organization) (I.R.S. Employer Identification No.) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2021 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission file number: 001-38663 G ...

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K (Mark One) ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2020 OR Commission File Number 001-38663 Gritstone Oncology, Inc. (Exact name of Registrant as specified in its Charter) (State or other jurisdiction of incorporation or organization) 5959 Horton Street, Suite 300 Emeryville, CA 94608 (Address of principal executive offices) (Zip Code) Delawa ...

1 Corporate Presentation J a n u a r y 2 0 2 1 2 Safe Harbor and Forward-Looking Statements This presentation contains forward-looking statements including, but not limited to, statements related to our preclinical and clinical product candidates, GRANITE, SLATE, CORAL and bispecific antibody programs. All statements other than statements of historical facts contained in this presentation, including statements regarding the timing of immunogenicity and clinical data for GRANITE SLATE, and CORAL, identificat ...

Mills Minis gritstone Gritstone Corporate Presentation August 2020 2 Safe Harbor and Forward-Looking Statements This presentation contains forward-looking statements including, but not limited to, statements related to our preclinical and clinical product candidates, GRANITE, SLATE, and our bispecific antibody program. All statements other than statements of historical facts contained in this presentation, including statements regarding the timing of immunogenicity and clinical data for GRANITE and SLATE, i ...

1 Gritstone Corporate Presentation J U N E 2 0 2 0 Safe Harbor and Forward-Looking Statements This presentation contains forward-looking statements including, but not limited to, statements related to our preclinical and clinical product candidates, GRANITE, SLATE, and our bispecific antibody program. All statements other than statements of historical facts contained in this presentation, including statements regarding the timing of immunogenicity and clinical data for GRANITE and SLATE, identification of d ...

Financial Performance - The company reported a net loss of $26.2 million for the three months ended March 31, 2020, compared to a net loss of $18.0 million for the same period in 2019, representing an increase in losses of $8.2 million[144]. - The total operating expenses for the three months ended March 31, 2020, were $27.9 million, an increase of $7.7 million compared to $20.3 million for the same period in 2019[144]. - The company has an accumulated deficit of $247.2 million as of March 31, 2020, and does not expect positive cash flows from operations in the foreseeable future[130]. - The net loss for the three months ended March 31, 2020, was $26.2 million, compared to a net loss of $18.0 million for the same period in 2019[164]. - Cash used in operating activities was $23.0 million for the three months ended March 31, 2020, compared to $19.1 million for the same period in 2019[163]. - The company expects to continue incurring significant losses for the foreseeable future as it develops its cancer immunotherapy candidates and does not expect positive cash flows from operations[156]. - The company has an accumulated deficit of $247.2 million as of March 31, 2020, reflecting ongoing operational losses since inception[160]. Research and Development - Research and development expenses increased to $22.5 million for the three months ended March 31, 2020, up from $15.9 million in the same period of 2019, reflecting a rise of $6.6 million[144]. - The company initiated a Phase 1/2 clinical trial of its personalized immunotherapy product candidate, GRANITE, in the fourth quarter of 2018, with the first patient dosed in the first quarter of 2019[123]. - The company has also initiated a Phase 1/2 clinical trial of its second product candidate, SLATE, in combination with immune checkpoint inhibitors, with the first patient dosed in the third quarter of 2019[124]. - The company anticipates needing substantial additional funding to support its operations and product development efforts in the future[157]. Revenue and Funding - Collaboration revenue from the bluebird Collaboration Agreement was $1.3 million for both the three months ended March 31, 2020, and 2019, showing a slight decrease of $85,000 year-over-year[145]. - The company raised net cash proceeds of $177.9 million from the issuance of convertible preferred stock and $20.0 million from a collaboration agreement with bluebird[151]. - Cash provided by financing activities was $5.7 million for the three months ended March 31, 2020, primarily from the issuance of common stock through the ATM Offering Program[168]. - The company anticipates seeking to fund operations through equity or debt financings or collaboration agreements, with adequate funding potentially impacted by the COVID-19 pandemic[128]. Operating Expenses - For the three months ended March 31, 2020, the company reported an increase in expenses of $6.6 million compared to the same period in 2019, primarily due to personnel-related costs increasing by $2.5 million and outside services increasing by $1.7 million[147]. - General and administrative expenses rose to $5.5 million for the three months ended March 31, 2020, up from $4.4 million in the same period in 2019, with a $0.5 million increase in personnel-related costs[148]. - The company expects to incur significant additional costs associated with operating as a public company and developing a sales organization or commercial infrastructure[127]. Cash and Securities - The company had cash, cash equivalents, and marketable securities of $108.9 million as of March 31, 2020, down from $127.8 million as of December 31, 2019[155]. Contracts and Agreements - The company entered into a contract research and testing agreement with a third-party CRO for antibody discovery services, with milestone payments of up to $34.8 million contingent on specified events, none of which had occurred as of March 31, 2020[174]. - The company has ongoing contracts with CROs for clinical trials and CMOs for clinical supply manufacturing, which are generally cancelable within 30 days[175]. Accounting Policies - Financial statements are prepared in accordance with GAAP, requiring management to make estimates and judgments affecting reported amounts of assets and liabilities[176]. - Management evaluates estimates related to preclinical study trial accruals and fair value of assets and liabilities, with actual results potentially differing from estimates[177]. - There have been no changes to critical accounting policies since the Annual Report on Form 10-K for the year ended December 31, 2019, filed on March 11, 2020[178]. - Recent accounting pronouncements are discussed in the notes to the unaudited interim condensed financial statements in the Quarterly Report on Form 10-Q[179]. - There have been no material changes in market risk since the Annual Report on Form 10-K for the year ended December 31, 2019[180].

1 Gritstone Corporate Presentation A P R I L 2 0 2 0 Safe Harbor and Forward-Looking Statements This presentation contains forward-looking statements including, but not limited to, statements related to our preclinical and clinical product candidates, GRANITE, SLATE, and our bispecific antibody program. All statements other than statements of historical facts contained in this presentation, including statements regarding the timing of immunogenicity and clinical data for GRANITE and SLATE, identification of ...

1 Gritstone Corporate Presentation M A R C H 2 0 2 0 Safe Harbor and Forward-Looking Statements This presentation contains forward-looking statements including, but not limited to, statements related to our preclinical and clinical product candidates, GRANITE, SLATE, and our bispecific antibody program. All statements other than statements of historical facts contained in this presentation, including statements regarding the timing of immunogenicity and clinical data for GRANITE and SLATE, identification of ...

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-K (Mark One) ☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2019 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 FOR THE TRANSITION PERIOD FROM TO Commission File Number 001-38663 Gritstone Oncology, Inc. (Exact name of Registrant as specified in its Charter) (State or other jurisdiction of incorporation o ...

SWHILE 1 % gritsstone Gritstone 38th Annual J.P. Morgan Healthcare Conference J A N U A R Y 1 6 , 2 0 2 0 Safe Harbor and Forward-Looking Statements 2 This presentation contains forward-looking statements including, but not limited to, statements related to our preclinical and clinical product candidates, GRANITE, SLATE, and our bispecific antibody program. All statements other than statements of historical facts contained in this presentation, including statements regarding the timing of immunogenicity and ...