Is First-Line Avelumab Effective for Metastatic Merkel Cell Carcinoma?

First-line avelumab monotherapy appears to have antitumor activity and a manageable safety profile in patients with metastatic Merkel cell carcinoma (mMCC), according to the results of an interim analysis of a phase II study. The investigators reported in JAMA Oncology that maturing progression-free survival (PFS) data suggest durable responses.

These findings provide clinical evidence for anti–programmed cell death ligand 1 (PD-L1) treatment, William H. Sharfman, MD, an associate professor of Oncology & Dermatology and the director of Cutaneous Oncology at The Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins, Baltimore, Maryland, told Cancer Network.

“I think it confirms what we reported in the New England Journal of Medicine, that the anti-PD1 pembrolizumab is active in metastatic Merkel cell [carcinoma]. Avelumab is anti-PDL1, but the same concept [applies],” Sharfman said.

D’Angelo et al found that treatment with avelumab resulted in a confirmed objective response rate of 62.1%. A total of 16 of 18 responses (88.9%) occurred by the first planned post-baseline assessment. Grade 3 treatment-related adverse events (AEs) occurred in 8 of 39 patients (20.5%). 

The JAVELIN Merkel 200 trial showed that avelumab, an anti–PD-L1 antibody, is effective as second-line or later treatment in patients with mMCC. D’Angelo and colleagues are evaluating the efficacy and safety of avelumab as first-line treatment for patients with distant mMCC (clinicaltrials.gov Identifier: NCT02155647).

So far, the JAVELIN Merkel 200 trial has enrolled 39 patients (30 men, 9 women). The median age is 75 years (range, 47–88 years), and the follow-up has been short (median follow-up, 5.1 months). In responding patients, the estimated proportion with a duration of response of at least 3 months was 93%. The researchers also found that avelumab was generally well-tolerated as a first-line treatment. No treatment-related deaths and no grade 4 adverse events occurred.

The researchers concluded that this agent is associated with early responses, high response rates, and a manageable safety profile. However, they cautioned that there has been only limited follow-up, and longer follow-up is warranted to evaluate overall survival (OS).

These results have not been compared with other immune checkpoint inhibitors for first-line therapy because data with extended follow-up have not been published for nivolumab and pembrolizumab. According to the study authors, it is not possible to make comparisons yet on long-term survival outcomes, TRAEs, and the economic impact of different immune checkpoint inhibitors as first-line therapy.

Anthony J. Olszanski, MD, RPh, vice chair of the Department of Hematology/Oncology at Fox Chase Cancer Center, Philadelphia, Pennsylvania, said that although the number of patients treated in the current study is small, the findings are consistent with other published data.

“The National Comprehensive Cancer Network (NCCN) guidelines support the use of checkpoint inhibitors as preferred agents for disseminated Merkel cell cancer and, based on what has been published, this recommendation is well-founded and a remarkable advance for patients with this disease,” Olszanski told Cancer Network.