Response and outcome of patients with melanoma skin metastases and immune checkpoint inhibition.

It is known, that different metastatic organ systems respond differently to immune checkpoint inhibitors (ICIs). In this study, we aimed to investigate the extent to which skin/subcutaneous metastases respond to ICI or targeted therapies (TTs) and whether the response rate differs from that of distant metastases in the same patient. Patients with melanoma diagnosed between January 2021 and September 2023 with at least one skin/subcutaneous metastasis who had received therapy with ICI or TT in an advanced setting were included in the analysis. Best overall response (BOR) was classified according to the revised response evaluation criteria in solid tumors (RECIST). The BOR of skin metastases and visceral metastases to ICI and TT was compared using the chi-square test. Skin metastases treated with ICI a first-line setting showed an overall response rate (ORR) of 44.1%. In contrast, visceral metastases had a higher ORR of 51.1%. However, the difference was not statistically significant (p = .77). Regarding TT, the ORR for skin metastases was 57.1%, compared to 38.5% for visceral metastases (p = .59). Interestingly, the ORR for skin/subcutaneous metastases was notably lower with ICI compared to visceral metastases, in contrast to patients who underwent TT. Skin metastases showed a poorer response to ICI than visceral metastases. Therefore, careful monitoring is recommended to detect non-response early in patients with skin metastases as skin metastases may have a worse response than TT. A larger cohort is needed for a comprehensive analysis and confirmation of our results.