Additional mediators of tumor immune cell activity in CRC cells include heat shock protein 90 (HSP90), for which the inhibitor XL888 is being combined with pembrolizumab, as well as Bruton’s tyrosine kinase (BTK) on MDSCs, for which the BTK-inhibitor ibrutinib is being combined with pembrolizumab in MSS CRC [46,47]. The gene discussed is BTK; the disease is colorectal carcinoma.