To examine further the factors that could contribute to treatment response or resistance among melanoma patients receiving anti-PD-1 and/or anti-CTLA-4 immunotherapy, we evaluated transcriptomic data from 7 independent datasets and found that indeed, the number of CTLs in the TME associates with patient response to ICI therapy, irrespective of the patient TMB status. The gene discussed is PDCD1; the disease is melanoma.