Gritstone Bio Inc. (GRTS) made headlines on Monday with the release of interim Phase 2 data for its individualized neoantigen-targeting immunotherapy, GRANITE, in frontline microsatellite-stable colorectal cancer (MSS-CRC). The study is designed to evaluate the efficacy of maintenance therapy with GRANITE (GRT-C901/GRT-R902) in combination with immune checkpoint inhibitors, compared to standard treatment alone.
The data revealed a significant benefit in the 50% of patients with lower disease burden at study entry, as measured by circulating tumor DNA (ctDNA) levels. Across all treated groups, GRANITE demonstrated a 21% relative risk reduction in disease progression or death compared to standard of care. Furthermore, a notable 33% (13/39) of patients receiving GRANITE and 23% (7/30) of control patients remained on the study without experiencing disease progression.
These results highlight the potential of GRANITE in patients with lower disease burden. Specifically, the low ctDNA subgroup experienced a 38% relative risk reduction in progression or death when treated with GRANITE.
While the data is encouraging, it’s important to note that the stock price took a significant hit on Tuesday, falling by 57.5% to $0.25. The decline can be attributed to concerns surrounding the overall impact of the results and the future path of development. Analysts at JMP Securities downgraded Gritstone Bio from Market Outperform to Market Perform, citing the positive results observed in the low-risk subgroup, but questioning whether they are sufficient to attract a significant investor base.
Despite the market reaction, Gritstone remains optimistic about the potential of GRANITE. The company plans to review the progression-free survival (PFS) data with the FDA in the coming months to determine the next steps, including a potential Phase 2 or 3 trial utilizing ctDNA levels as eligibility criteria.
In addition to the clinical update, Gritstone announced that it has engaged Raymond James as its financial advisor. The company will likely be working with Raymond James to explore different avenues for financing and strategic partnerships as they move forward with the development of GRANITE.
The future of GRANITE in the treatment of MSS-CRC remains uncertain, but the interim Phase 2 data provides a glimmer of hope for patients seeking new treatment options. The FDA’s input and the decision regarding future trials will be key to determining the long-term success of this promising immunotherapy.
