Rate of response to immune checkpoint inhibitor therapy in patients with conjunctival melanoma

Our primary objective was to estimate the overall response rate to immune checkpoint inhibitors (ICIs) in patients with locally advanced, multiply recurrent, or metastatic conjunctival melanoma treated with ICIs. A retrospective review of all consecutive conjunctival melanoma patients who were treated with ICI between October 2017 and January 2024 was carried out. The study included 16 patients with a median age of 66 years. The indications for ICI were locally extensive conjunctival melanoma in the eye/orbital area without nodal or distant metastasis in 10 patients, local recurrence of conjunctival melanoma and simultaneous nodal or distant metastasis in four patients, and metastatic conjunctival melanoma without local recurrence in two patients. Five patients received PD-1 inhibitor monotherapy with nivolumab or pembrolizumab; the other 11 received ipilimumab (CTLA-4 inhibitor) and nivolumab for several cycles and were then continued on nivolumab monotherapy (n = 6) or not given additional ICI therapy (n = 3). The number of cycles of ICI ranged from 2 to 25 (median, 13). Eight patients achieved a complete response. Six patients had progressive disease. The overall rate of objective response to ICI therapy was 63% (10 of 16), and for the subset of patients with local disease only, the objective response rate was 70% (7 of 10). In 14 patients (88%), orbital exenteration or additional extensive surgery was avoided; two patients had progression despite ICI and eventually needed an orbital exenteration. Future studies should aim to correlate biomarker data with response to ICI therapy in patients with conjunctival melanoma.