# GRT-C901

Source: https://onco.cc/drugs/grt-c901/  
OnCo record `grt-c901` (Treatment). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

GRT-C901 is an experimental cancer vaccine from Seattle Project in phase 3 trials for colorectal cancer, with its target not yet stated publicly.

## Summary

GRT-C901 is a cancer vaccine developed by Seattle Project. The sponsor describes its target as patient-specific neoantigens, which OnCo does not yet have a target page for. The sponsor states: A patient-specific neoantigen cancer vaccine given as the prime dose (1x10^12 viral particles, intramuscular) in a heterologous prime/boost regimen with GRT-R902, combined with checkpoint inhibition, intended to generate T-cell responses specific to each patient's tumour mutations. ClinicalTrials.gov describes the intervention as: A patient-specific neoantigen cancer vaccine administered via intramuscular (IM) injection as prime and single boost at a dose of 1x10\^12 viral particles 2 times over the course of the first year. It is the investigational product in 1 recruiting or active industry-led phase 2 and phase 3 interventional cancer trial, including the phase 3 study NCT05141721 (A Study of a Patient-Specific Neoantigen Vaccine in Combination With Immune Checkpoint Blockade for Patients With Metastatic Colorectal Cancer), in colorectal cancer. The largest, NCT05141721, plans to enrol 700 participants with primary completion expected 2027-03. Status reflects the highest phase registered on ClinicalTrials.gov; no efficacy results are recorded here.

## Fields

- Kind: Treatment
- Status: phase-3
- Last checked: 2026-09-11
- Tags: pipeline; ctgov-ingest
- Modality: vaccine
- Mechanism: A patient-specific neoantigen cancer vaccine given as the prime dose (1x10^12 viral particles, intramuscular) in a heterologous prime/boost regimen with GRT-R902, combined with checkpoint inhibition, intended to generate T-cell responses specific to each patient's tumour mutations.

## Sources

- ClinicalTrials.gov: trials of GRT-C901: https://clinicaltrials.gov/search?intr=GRT-C901

## Connected records

- cancers: [Colorectal cancer](https://onco.cc/cancers/colorectal/)
- companies: [Gritstone bio](https://onco.cc/companies/gritstone/)
- trials: [A Study of a Patient-Specific Neoantigen Vaccine in Combination With Immune Checkpoint Blockade for Patients With Metastatic Colorectal Cancer](https://onco.cc/trials/nct05141721/)

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JSON: https://onco.cc/api/v1/entities/grt-c901.json