Atezolizumab plus bevacizumab in advanced Merkel cell carcinoma: A prospective study

Merkelcell.org Summary

PD-1/PD-L1 axis inhibitors are immunotherapies like Keytruda and Bavencio that help the immune system fight cancer and have become the standard treatment for Merkel cell carcinoma that has spread (metastatic MCC) or can’t be treated with surgery or radiation. Another type of drug, VEGF inhibitors, slows the abnormal growth of blood vessels and is used to treat other types of cancer. This clinical trial studied the combination of immunotherapy and VEGF inhibitors in 11 patients with metastatic MCC to see how effective the combination is. Seven out of the 11 patients (64%) had all or some of their MCC treated successfully, compared to 62% previously reported for immunotherapy alone. Patients remained MCC-free for an average of 16 months, however, four out of the 11 patients experienced severe side effects. These results suggest that combining immunotherapy and VEGF inhibitors may generally be effective and worth further investigation, though there is no evidence yet that the combination is more effective than immunotherapy alone. This study finished earlier than scheduled and had a small number of participants because many patients chose to be treated with immunotherapy alone rather than participating in the trial. Still, it’s the first study of its kind in MCC and provides important information about this treatment combination.

Abstract

Merkel cell carcinoma (MCC) is a rare and aggressive skin neuroendocrine carcinoma. Since 2017, the standard treatment for advanced MCC is PD-1/PD-L1 axis inhibitors (PD1i), three of which, avelumab, pembrolizumab, and retifanlimab, are approved by the US Food and Drug Administration. Overexpression of vascular endothelial growth factor (VEGF) has been linked to aggressive MCC. Preclinical studies indicate that VEGF inhibitors and PD1i may be synergistic. We conducted a phase II study to assess the efficacy and safety of atezolizumab plus bevacizumab (VEGFi) in rare tumors. Here we report the outcomes for MCC.