Atezolizumab–bevacizumab combo shows therapeutic potential in advanced mucosal melanoma

The combination of atezolizumab plus bevacizumab demonstrates promising antitumour activity in patients with advanced mucosal melanoma while having a manageable safety profile, according to the results of a phase II study.

In the multicentre, open-label study, 43 patients were given atezolizumab at a fixed dose of 1,200 mg plus bevacizumab at 7.5 mg/kg. Treatment was administered intravenously every 3 weeks. Median follow-up was 13.4 months at data cutoff.

Of the patients, 20 (46.5 percent) had unresectable and 23 (53.5 percent) had metastatic mucosal melanoma. Their median age was 61 years, and about three-fourths had an Eastern Cooperative Oncology Group Performance Status Scale score of 0 (74.4 percent). The median sum of diameters of target lesion at baseline was 36.3 mm.

The most common metastatic sites were the lung (56.5 percent), lymph node (43.5 percent), and liver (21.7 percent). BRAF, NRAS, and KIT mutations were identified in one (2.3 percent), six (14 percent), and six (14 percent) patients, respectively.

Response was evaluated in 40 patients. The primary endpoint of objective response rate per RECIST v1.1 was 45.0 percent (95 percent confidence interval [CI], 29.3–61.5), with one patient showing complete response and 17 with partial responses.

Median progression-free survival (PFS) was 8.2 months (95 percent CI, 2.7–9.6), with PFS rates being 53.4 percent (95 percent CI, 36.6–67.6) at 6 months and 28.1 percent (95 percent CI, 14.2–43.9) at 12 months. Meanwhile, median overall survival (OS) was not reached, with 6- and 12-month OS rates being 92.5 percent (95 percent CI, 78.5–97.5) and 76.0 percent (95 percent CI, 57.1–87.5), respectively.

Duration of response was a median of 12.5 months (95 percent CI, 5.5–NR).

Treatment-related adverse events were recorded in 90.7 percent (39/43) of patients, with 25.6 percent (11/43) experiencing grade ≥3 events.