In a Chinese phase Ib study reported in the Journal of Clinical Oncology, Sheng et al reported activity with the combination of the anti–programmed cell death protein 1 (PD-1) agent toripalimab plus axitinib in patients with metastatic mucosal melanoma.

As stated by the investigators, whereas mucosal melanoma is rare in white populations, it constitutes the second most common melanoma subtype in Asian patients and does not respond well to anti–PD-1 therapy alone.

Study Details

The dose-escalation and cohort expansion study included 33 patients treated between April 2017 and April 2018 at Peking University Cancer Hospital with toripalimab 1 or 3 mg/kg every 2 weeks plus axitinib 5 mg twice a day until disease progression, unacceptable toxicity, or voluntary withdrawal. A total of 31 patients were chemotherapy-naive.

Toxicity

No dose-limiting toxicities were observed. The most common treatment-related adverse events of any grade were diarrhea (61%), proteinuria (58%), hand-foot syndrome (58%), and elevated cholesterol (55%). Grade ≥ 3 treatment-related adverse events occurred in 39% of patients, with the most common being proteinuria (9%), hypertension (9%), and neutropenia (9%). The most common immune-related adverse events of any grade were diarrhea (61%), hypothyroidism (52%), and alanine transaminase elevation (42%).

Response Rates

Median duration of treatment was 9.4 months. Among 29 evaluable patients (all chemotherapy-naive), objective response on RECISTv1.1 was observed in 14 (48.3%). The disease control rate was 86.2%. Median duration of response was not reached, with ongoing responses reported in 11 responders at the time of analysis. Median progression-free survival was 7.5 months (95% confidence interval = 3.7 months–not reached). On immune-related RECIST criteria, the objective response rate was 51.7% and median progression-free survival was 8.9 months.

The investigators concluded, “The combination of toripalimab plus axitinib was tolerable and showed promising antitumor activity in patients with treatment-naive metastatic mucosal melanoma. Patients enrolled in this study were all Asian, and this combination therapy must be validated in a randomized phase III trial that includes a non-Asian population before it can become a standard of care.”

Jun Guo, MD, PhD, of Peking University Cancer Hospital, Beijing, is the corresponding author for the Journal of Clinical Oncology article.

Disclosure: The study was supported by Shanghai Junshi Biosciences, grants from the National Natural Science Foundation of China, and others. For full disclosures of the study authors, visit jco.ascopubs.org.