This prospective study investigated the efficacy and safety of pembrolizumab as a first-line therapy for metastatic uveal melanoma.

Study design

This observational single-arm study included 17 patients who received a median of 8 cycles (range 2–28). Efficacy was evaluated in terms of progression-free survival, response rate, and overall survival. Toxicity was also assessed.

Outcomes

Two patients (11.7%) achieved a partial treatment response, while 6 (35.3%) demonstrated disease stabilization and 9 (53%) experienced disease progression. None of the patients achieved a complete treatment response. The progression-free survival time was 3.8 months; this increased to 9.7 months for individuals who developed metastatic disease at least 5 years after diagnosis and decreased to 2.6 months for those with an interval less than 5 years (HR 0.2; P=0.039).

The average survival time was 12.8 months for patients who experienced a clinical benefit, while overall survival for progressive patients was 3.1 months. PD-L1 expression and genomic abnormalities predictive of relapse after diagnosis of the primary tumor were not associated with progression-free survival. Toxicity was mild, without grade 3 to 4 side effects.

Limitations

The study was limited by the small sample size.

Clinical significance

Similar to other immunotherapies, pembrolizumab does not seem particularly effective for treating metastatic uveal melanoma. Newer therapies are needed, including adjuvant treatments and therapies for metastatic uveal melanoma.