Pretreatment CD8+PD-1+ to CD4+PD-1+ ratio is associated with the prognosis of advanced melanoma patients treated with PD-1 inhibitors.

The aim of this study is to determine whether the pretreatment CD8+PD-1+ to CD4+PD-1+ (PERLS) ratio is an independent risk prognostic factor of advanced melanoma patients. We retrospectively analyzed the efficacy and flow cytometry data from advanced melanoma patients who received PD-1 inhibitor as monotherapy between January 1, 2018 and January 26, 2022. Fifty-nine patients were enrolled, the PERLS cutoff was 1.125. PERLS did not correlate with clinical characteristics but were significantly associated with baseline CD8+, CD4+, and CD8+PD-1+ T cells. The mean overall survival and the progression-free survival were 45.8 and 17.1 months for the low PERLS group (n = 39), compared with 29.9 (P = 0.001) and 9.7 (P = 0.003) months for the high PERLS group (n = 20), respectively. Pretreatment PERLS might contribute to selecting patients before receiving anti-PD-1 therapy.