Using CRISPR/Cas9 genome editing we generated JAK1, JAK2 and B2M knockout (KO) sublines of the murine MC38 carcinoma, a model of high mutational load cancer that responds well to anti-PD-1, as well as of human MART-1-positive melanoma cell lines, tested using in-vitro T cell co-culture systems. The gene discussed is PDCD1; the disease is melanoma.