Mucosal melanoma is rare, accounting for only approximately 1% of all melanoma. Whilst immune checkpoint inhibitors (ICI) have become the standard of care in advanced cutaneous melanoma, less is known about their efficacy in mucosal melanoma. We report our experience of ICI therapy in patients with advanced mucosal melanoma.
Medical records of all patients with mucosal melanoma who received ICI between January 2014 and December 2016 in our institution were retrospectively reviewed in this cross-sectional, observational study. Objective response, treatment-related toxicity, progression-free survival (PFS) and overall survival (OS) were analyzed.
Seventeen patients received ipilimumab (n=11), pembrolizumab (n=5) or nivolumab (n=1). The majority was female (n=14), ≤ 65 years of age (n=11) and, at the time of commencing ICI, had an elevated LDH (n=9), M1c disease (n=14), and no mutation detected in BRAF, KIT or NRAS (n=12). Two patients, both had ipilimumab, had an objective response, including one complete response, ongoing for 21+ months at the time of data cut-off. In addition, three patients, after treatment with pembrolizumab, had stable disease. Overall, the objective response rate was 11.8% and the disease control rate was 29.4%. Three patients ceased treatment due to immune-related adverse events. Five patients who progressed after ipilimumab proceeded to receive pembrolizumab; there was one partial response and one complete response, both durable, for 36.9 and 47.7+ months respectively. After ICI, another 5 patients received other forms of treatment, including chemotherapy (n=4) and investigational agent in a phase I clinical trial (n=1). After a median follow-up of 10.1 months, the median PFS and OS was 3.1 and 8.8 months respectively.
ICI therapy may be effective in mucosal melanoma, although the response rate and prognosis remain poor. Other treatment strategies such as sequential or combination ICI need to be explored for this rare melanoma subtype.