Melphalan ILP (regional alkylator): CD8+ phenotype predicts CR in in-transit melanoma

Melphalan-based isolated limb perfusion (ILP) delivers high-dose regional alkylating chemotherapy; this single-center retrospective study (Sweden) tested whether baseline peripheral-blood immunophenotype predicts response after first-time ILP for melanoma in-transit metastases. Among 132 treated patients, 119 were evaluable and 53% achieved complete response by RECIST 1.1 modified for cutaneous lesions—consistent with historical ILP results (CR ~40–60%, ORR ~90%). On multivariable models adjusting for age, sex, lesion count and size, higher %CD3+CD8+ T cells (OR 1.07 per 1% increase, 95%CI 1.02–1.13, p=0.012) and %CD3+CD8+CD45RA+ naïve T cells (OR 1.11 per 1% increase, 95%CI 1.01–1.22, p=0.029) independently predicted CR; safety outcomes were not reported. An ILP+PD-1 strategy is under prospective evaluation (NCT03685890).