Safety and Activity of PolyPEPI1018 Plus Atezolizumab in Colorectal Cancer.

This is a multicenter, open label, phase II trial to determine the safety, tolerability, and immunogenicity and initial clinical activity of the combination treatment of PolyPEPI1018 vaccine and atezolizumab in participants with MSS CRC who have progressed on 2 or 3 prior regimens. Both agents will be administered on an every-3-week schedule until documented progression. A Simon's 2-stage design will be used for the initial assessment of efficacy.