A Phase 2/3, Randomized, Open-Label Study of Maintenance GRT-C901/GRT-R902, A Neoantigen Vaccine, in Combination With Immune Checkpoint Blockade for Patients With Metastatic Colorectal Cancer

  • End date
    Mar 24, 2027
  • participants needed
  • sponsor
    Gritstone bio, Inc.
Updated on 24 October 2022


The primary objective of the Phase 2 portion of the study is to characterize the clinical activity of maintenance therapy with GRT-C901/GRT-R902 in combination with checkpoint inhibitors in addition to fluoropyrimidine/bevacizumab versus fluoropyrimidine/bevacizumab alone as assessed by changes in circulating tumor (ct)DNA. The primary objective of the Phase 3 portion is to demonstrate clinical efficacy of the regime as assessed by progression-free survival.


Tumors harboring non-synonymous deoxyribonucleic acid (DNA) mutations can present peptides containing these mutations as non-self antigens in the context of human leukocyte antigens (HLAs) on the tumor cell surface. A fraction of mutated peptides result in neoantigens capable of generating T-cell responses that exclusively target tumor cells. Sensitive detection of these mutations allows for the identification of neoantigens unique to each patient's tumor to be included in a personalized cancer vaccine that targets these neoantigens. This vaccine regimen uses two vaccine vectors as a heterologous prime/boost approach (GRT-C901 first followed by GRT-R902) to stimulate an immune response. This study will explore the anti-tumor activity of this patient-specific immunotherapy in combination with checkpoint inhibitors in addition to fluoropyrimidine/bevacizumab.

Condition Colorectal Neoplasms
Treatment Ipilimumab, bevacizumab, Oxaliplatin, Atezolizumab, Fluoropyrimidine, GRT-C901, GRT-R902
Clinical Study IdentifierNCT05141721
SponsorGritstone bio, Inc.
Last Modified on24 October 2022


Yes No Not Sure

Inclusion Criteria

Patients with histologically confirmed metastatic colorectal cancer (CRC) who are planned for, or have received no more than 1 cycle of first-line treatment in the metastatic setting with a fluoropyrimidine and oxaliplatin in combination with bevacizumab
Measurable and unresectable disease according to RECIST v1.1
Availability of formalin-fixed paraffin-embedded (FFPE) tumor specimens
Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1
Patient has adequate organ function in opinion of investigator
If women of childbearing potential (WCBP), must be willing to undergo pregnancy testing and agrees to the use at least 1 highly effective contraceptive method during the study treatment period and for 150 days after last investigational study treatment

Exclusion Criteria

Patients with deficient mismatch repair (dMMR) or high levels of microsatellite instability (MSI-H) phenotype
Patient has a known tumor mutation burden <1 non-synonymous mutations/megabase
Known DNA Polymerase Epsilon mutations
Patients with known BRAFV600E mutations
Bleeding disorder or history of significant bruising or bleeding following IM injections or blood draws
Immunosuppression anticipated at time of study treatment
History of allogeneic tissue/solid organ transplant
Active or history of autoimmune disease or immune deficiency
Patient with symptomatic or actively progressing central nervous system (CNS) metastases, carcinomatous meningitis, or has been treated with whole brain radiation
History of other cancer within 2 years with the exception of neoplasm that has undergone potentially curative therapy
Any severe concurrent non-cancer disease that, in the judgment of the Investigator, would make the patient inappropriate for the current study
Active tuberculosis or recent (<2 weeks) clinically significant infection, evidence of active hepatitis B or hepatitis C, or known history of positive test for HIV
History of pneumonitis requiring systemic steroids for treatment (with the exception of prior resolved in-field radiation pneumonitis)
Myocardial infarction within previous 3 months, unstable angina, serious uncontrolled cardiac arrhythmia, history of myocarditis, or congestive heart failure
Pregnant, planning to become pregnant, or nursing
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