The purpose of this study is to find out what effects an immunotherapy drug, called pembrolizumab, combined with a radioactive drug, called lutetium Lu 177 dotatate (Lutathera®) have on Merkel cell carcinoma.

Pembrolizumab works by helping the immune system to fight cancer and Lutathera works by killing cancer cells. The goal of this research study is to estimate the number of people whose tumor resolves or almost resolves after receiving lutetium dotatate and pembrolizumab. This will help study doctors learn whether pembrolizumab in combination with Lutathera cause Merkel cell cancers to resolve or almost resolve, after they stopped responding to standard immunotherapy.

Pembrolizumab is approved by the U.S. Food and Drug Administration (FDA) to treat Merkel cell cancer and has caused some Merkel cell cancers to shrink and/or resolve. Lutathera is FDA-approved to treat some neuroendocrine tumors and has caused some patient’s neuroendocrine tumors to shrink and allowed them to live longer, but it is not approved by the FDA to treat Merkel cell cancer. The combination of Lutathera and pembrolizumab to treat Merkel cell cancer is considered investigational, which means this combination is not approved by the FDA for this use.

There are two parts to this study. Part one aims to determine the safe dose of Lutathera and pembrolizumab. Part two will study how well tumors respond to Lutathera and pembrolizumab. All study participants will receive both Lutathera and pembrolizumab at doses and frequency determined by the study team.  

Total study participation will last approximately 2 years.