Positive Preliminary PFS and Long-term ctDNA Data from Ph 2 Portion of Ongoing Ph 2/3 Study of Personalized Cancer Vaccine, GRANITE, in 1L Metastatic MSS-CRC announced

“Today’s preliminary Phase 2 results are highly encouraging and represent the first randomized trial evidence, albeit early, that a personalized neoantigen-directed vaccine can potentially drive efficacy in a metastatic ‘cold’ tumor. The overall trend of PFS improvement in GRANITE recipients is great to see, and the exploratory PFS hazard ratio of 0.52 in the high-risk group, a more mature dataset, is a striking signal,” said Andrew Allen, MD, PhD, Co-founder, President & CEO of Gritstone bio. “Pioneering new spaces carries inherent risks, and with regard to defining molecular response, we simply got it wrong. ctDNA levels in both arms decreased on chemotherapy for longer than we anticipated, generating similar short-term molecular response rates across arms and rendering our protocol measure of ctDNA change uninformative. Fortunately, long-term analysis demonstrates the expected correlation of ctDNA with clinical benefit and favors GRANITE patients. We believe these preliminary findings put us in a strong position to share mature PFS data in the third quarter and then enter regulatory discussions regarding Phase 3. The growing body of evidence favoring GRANITE in this trial, including positive PFS and long-term ctDNA trends in both high and low-risk populations, is exciting and suggests GRANITE is working in this notoriously underserved patient population.”