HDAC9 and colorectal carcinoma: Interestingly, a randomised phase 2 trial was performed on a combination of PD-1 antibody, HDAC inhibitor, and VEGF antibody in MSS chemotherapy refractory MMR-proficient tumours, showing promising results and providing a basis for the importance of combinatorial treatment involving PD-1/PD-L1 blockers in MSS CRC tumours55.