Gritstone’s GRANITE Vaccine Shows Encouraging but Limited Benefit in Metastatic Colorectal Cancer

Interim Phase 2 Data:
Gritstone bio announced interim Phase 2 data for GRANITE, an individualized neoantigen targeting immunotherapy, in frontline metastatic microsatellite-stable colorectal cancer (MSS-CRC). The data showed a 21% relative risk reduction of progression or death with GRANITE compared to the control group in the overall treated population.

Subgroup Analysis:
Patients with lower disease burden, as measured by circulating tumor DNA (ctDNA) at study entry, demonstrated a 38% relative risk reduction of progression or death with GRANITE compared to the control group.

Safety and Tolerability:
GRANITE exhibited a favorable safety and tolerability profile, with no patients discontinuing treatment due to adverse events. Common adverse events were mild systemic and local effects associated with potent vaccines.

Future Plans:
Gritstone plans to review the progression-free survival (PFS) data with the FDA and discuss next steps, including a potential Phase 2 or 3 trial using ctDNA levels as eligibility criteria.

Clinical Context:
Metastatic colorectal cancer is a challenging condition with limited treatment options, particularly for patients with MSS-CRC who often do not benefit from checkpoint inhibitors. GRANITE aims to address this unmet need by targeting neoantigens to stimulate an immune response.

Financial Update:
Gritstone completed an underwritten public offering in April 2024, raising $32.5 million in gross proceeds to support its ongoing clinical programs.