Uveal melanoma is the most common intraocular
malignancy and has a poor prognosis compared to other
melanoma subtypes with a median overall survival of 6-10 months. With
immune checkpoint inhibitor therapy, either
PD-1 inhibitor alone or combination
ipilimumab/
nivolumab (anti-CTLA-4/anti-PD-1), responses are rare and often not durable. We present a case report of a now 66-year-old woman with diffuse metastatic
uveal melanoma previously treated with a combination of
ipilimumab/
nivolumab, followed by maintenance
nivolumab. Almost complete resolution of all sites of metastatic disease was observed except for one liver
metastasis which regressed partially on
immunotherapy. Notably, the patient had a significantly elevated BMI and developed widespread
vitiligo on treatment. Whole-genome and transcriptome analysis was performed on the residual liver biopsy and molecular markers that may have contributed to the exceptional response were investigated. Several alterations were observed in genes involved in T-cell responses. Estimates of tumour infiltrating immune cells indicated a high level of plasma cells compared to other
uveal melanoma cases, a finding previously associated with indolent disease. The patient also carried several germline SNPs that may have contributed to her treatment response as well as widespread
vitiligo. Whole-genome and transcriptome sequencing have provided insight into potential molecular underpinnings of an exceptional treatment response in a tumour type typically associated with poor prognosis. Immunological findings suggest a role for plasma cells in the tumour microenvironment. Elevated BMI and the development of
vitiligo may be clinically relevant factors for predicting response to
immune checkpoint inhibitor therapy, warranting further studies in patients with
uveal melanoma.