Grapiprant and Pembrolizumab in Patients With Advanced or Progressive MSS Colorectal Cancer

This study will be conducted in adult participants diagnosed with any form of an advanced or progressive MSS CRC for which 1st and 2nd line standard therapy (at least one of which contained fluorouracil) is no longer effective or is intolerable. This is a phase 1b, multi-center, open label study designed to assess safety and tolerability of grapiprant in combination with pembrolizumab, to determine the recommended phase 2 dose (RP2D) with pembrolizumab, and to evaluate and characterize the PK of grapiprant alone and in combination with pembrolizumab. Disease response, pharmacodynamics, and response biomarkers will also be assessed.