Gritstone bio
Corporate brand
UnclaimedGritstone bio was a U.S. clinical-stage biotechnology company focused on cancer immunotherapies and vaccines for infectious diseases.
Last updated August 24, 2026
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Overview
Gritstone bio was a clinical-stage biotechnology company based in Emeryville, California. Founded in August 2015 as Gritstone Oncology, the company sought to use computational biology, tumor genomics, and immune-engineering technologies to develop therapeutic vaccines and other immunotherapies for cancer. It later broadened its work to include vaccines for infectious diseases, including a self-amplifying messenger RNA candidate designed to generate responses against SARS-CoV-2. The company’s oncology work centered on personalized and shared-antigen approaches intended to stimulate T-cell and other immune responses against malignant cells. Gritstone entered a Phase 1/2 study conducted in collaboration with Bristol Myers Squibb involving patients with metastatic solid tumors. The program reflected the company’s effort to combine its immunotherapy platform with established oncology development and commercialization capabilities. During the COVID-19 pandemic, Gritstone applied its vaccine-development technology to SARS-CoV-2. Its GRT-R910 candidate used a self-amplifying mRNA design delivered in lipid nanoparticles. The vaccine was intended to present the stabilized viral spike protein together with more conserved viral regions containing T-cell epitopes, potentially broadening immune responses beyond the rapidly changing spike protein. In September 2021, Gritstone began a Phase 1 study at the NIHR Manchester Clinical Research Facility at Manchester Royal Infirmary. The study evaluated whether GRT-R910 could boost and broaden immunity in healthy adults over 60 who had previously received AstraZeneca’s first-generation COVID-19 vaccine, AZD1222, also known as Vaxzevria. In November 2021, the company reported positive preclinical results from non-human-primate studies of the vaccine. Gritstone remained a clinical-stage developer rather than a commercial pharmaceutical company. Its programs had not established an approved marketed product in the reference material. Financial and corporate pressures ultimately led the company to pursue strategic alternatives. Gritstone filed for Chapter 11 bankruptcy protection in October 2024 while seeking a path forward for its assets and business. Following an asset sale, co-founder, President, and Chief Executive Officer Andrew Allen stepped down on December 31, 2024, along with other key executives. The company’s bankruptcy process and asset disposition marked the end of Gritstone bio as an independent operating biotechnology brand.
History
Gritstone bio was established in August 2015 under the name Gritstone Oncology, Inc. The company entered biotechnology at a time when advances in tumor sequencing, computational antigen selection, and immune-cell biology were reshaping the development of cancer vaccines and immunotherapies. Its original focus was oncology, with programs intended to identify tumor-associated or patient-specific targets and use them to generate immune responses against cancer. The company’s development strategy included both personalized and broader immunotherapy concepts. Personalized approaches seek to design treatment around an individual patient’s tumor profile, while shared-antigen programs target biological features found across groups of patients. Gritstone’s oncology activities included a Phase 1/2 study carried out with Bristol Myers Squibb in 26 patients with metastatic solid tumors. The collaboration placed Gritstone’s platform in a clinical setting involving advanced cancer while allowing it to work alongside a major established pharmaceutical company. Gritstone later expanded beyond cancer into infectious-disease vaccines. During the COVID-19 pandemic, it developed GRT-R910, a second-generation self-amplifying mRNA vaccine candidate against SARS-CoV-2. The approach used lipid nanoparticles to deliver genetic instructions for a broad antigen set. In addition to a stabilized form of the coronavirus spike protein, the candidate included conserved viral regions containing T-cell epitopes. This design was intended to stimulate broader cellular immunity and potentially retain relevance as the virus changed. In September 2021, Gritstone initiated a Phase 1 clinical trial at the NIHR Manchester Clinical Research Facility at Manchester Royal Infirmary. The study focused on healthy adults older than 60 and examined whether GRT-R910 could boost and expand immune responses in people who had received AstraZeneca’s first-generation COVID-19 vaccine, AZD1222, marketed as Vaxzevria. On November 10, 2021, Gritstone announced positive preclinical results from non-human-primate testing of its self-amplifying mRNA vaccine. These developments made the vaccine program one of the company’s most visible activities outside oncology. Gritstone did not reach commercial product status in the material available for this dossier. It remained a clinical-stage biotechnology company whose value depended on the progress of experimental assets, clinical data, partnerships, and access to capital. In October 2024, the company filed for Chapter 11 bankruptcy protection as part of a strategic-alternatives process. The bankruptcy process was accompanied by an effort to move forward with an asset sale. After that transaction, Andrew Allen stepped down on December 31, 2024, from his positions as co-founder, President, and Chief Executive Officer, and other key executives also left. The asset sale, bankruptcy proceeding, and executive departures marked the conclusion of Gritstone bio’s independent corporate operations.
- 2024
Chapter 11 bankruptcy filing
[1]Gritstone filed for Chapter 11 protection in October while pursuing strategic alternatives and a path involving its assets.
- 2024
Executive transition after asset sale
[1]Andrew Allen left the company on December 31 following the asset sale, together with other key executives.
- 2021
GRT-R910 enters a Phase 1 COVID-19 vaccine study
[1]Gritstone began a Phase 1 study of its self-amplifying mRNA SARS-CoV-2 vaccine in older adults previously vaccinated with AstraZeneca’s AZD1222.
- 2021
Positive non-human-primate vaccine data announced
[1]On November 10, Gritstone announced positive preclinical findings for its second-generation self-amplifying mRNA SARS-CoV-2 vaccine in non-human-primate models.
- 2015
Founded as Gritstone Oncology
[1]The company was founded in August 2015 as Gritstone Oncology, Inc., with a focus on developing cancer immunotherapies and therapeutic vaccines.
Products and positioning
A clinical-stage biotechnology developer positioned around computationally informed cancer immunotherapy and next-generation vaccine technologies, particularly self-amplifying mRNA and T-cell-focused immune responses.
Self-amplifying mRNA SARS-CoV-2 vaccine · 2021
GRT-R910
GRT-R910 was an experimental second-generation self-amplifying mRNA vaccine candidate against SARS-CoV-2. Delivered using lipid nanoparticles, it was designed to encode the stabilized spike protein as well as conserved viral regions containing T-cell epitopes. Gritstone began a Phase 1 study in September 2021 in healthy adults over 60 who had previously received AstraZeneca’s AZD1222 vaccine. The candidate was intended to examine whether a broader antigen design could expand and strengthen immune responses.
Oncology immunotherapy and therapeutic vaccines
Cancer immunotherapy programs
Gritstone’s core oncology portfolio comprised experimental immunotherapies and therapeutic vaccine approaches aimed at directing immune responses toward tumor-associated, shared, or patient-specific antigens. The company was involved in a Phase 1/2 metastatic solid-tumor study conducted with Bristol Myers Squibb and involving 26 patients. The programs were clinical-stage research assets rather than approved commercial medicines.
Brand decisions
2024
Pursue strategic alternatives through Chapter 11StrategyBackground
Gritstone faced a corporate situation in which it sought a path forward for its business and development assets.
Action taken
In October 2024, the company filed for Chapter 11 bankruptcy protection while pursuing strategic alternatives and an asset sale process.
Aftermath
Following the asset sale, co-founder and chief executive Andrew Allen stepped down on December 31, 2024, and other key executives also departed.
2021
Advance GRT-R910 into human testingProduct launchBackground
Gritstone developed a self-amplifying mRNA vaccine candidate intended to broaden immune recognition of SARS-CoV-2 through spike and conserved viral antigens.
Action taken
The company began a Phase 1 study in September 2021 in older adults previously vaccinated with AstraZeneca’s AZD1222.
Aftermath
The program received additional visibility after Gritstone reported positive preclinical non-human-primate data in November 2021. No approved commercial product is identified in the available material.
Recent events
Sources2 sources
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