The phase 1b study provided long-term results form the KEYNOTE-041 trial. 

A recent analysis of the phase 1b KEYNOTE-041 trial indicated effectiveness and tolerability of pembrolizumab in Japanese patients with advanced melanoma.

Researchers conducted the study over a 12-month period. The study evaluated pembrolizumab's long-term efficacy and safety in individuals with locally advanced (unresectable stage III) or metastatic (stage IV) melanoma who were ineligible for local therapy. Patients had all received limited prior systemic treatments. The study drug was administered at a dosage of 2 mg/kg every 3 weeks for up to 2 years or until confirmed disease progression or intolerable side effects.

According to the results, pembrolizumab exhibited a promising overall response rate (ORR) of 24.3% among evaluable patients, with two patients achieving complete response following initial partial response. Median overall survival (OS) reached 25.1 months, with a 30-month OS rate of 46.3%, indicating durable antitumor activity. Furthermore, the median duration of response was not reached, suggesting sustained efficacy over the observation period.

Treatment-related adverse events (TRAEs) were reported in 78.6% of patients, with grade 3 to 5 TRAEs observed in 23.8% of cases. Notably, no additional treatment-related deaths were recorded since the initial analysis, underscoring pembrolizumab's acceptable safety profile in this patient cohort.

"Pembrolizumab continued to provide durable antitumor activity in Japanese patients, the authors wrote in the study, publishing in the Journal of Dermatology. These findings provide further support for the use of pembrolizumab monotherapy in Japanese patients with advanced melanoma."

Source: Yokota K, Tatsuya Takenouchi, Fujisawa Y, et al. Long‐term follow‐up results from KEYNOTE‐041: Phase 1b study of pembrolizumab in Japanese patients with advanced melanoma. J Dermatol (Print). Published online March 26, 2024.