A new report over the use of Pembrolizumab for patients with advanced Merkel cell carcinoma (MCC) revealed the drug having longer lasting tumor control, durable tumor regression, moderate and manageable side effects and improved overall survival. The project was a collaborative effort among some of the most important centers and universities in the United States.
“The study drug, pembrolizumab, which is a new form of immunotherapy, blocks a specific receptor in our bodies, resulting in supercharging of our immune system to both recognize and destroy cancer cells. The overall impressive results show that this form of immunotherapy is quite effective, giving us an important treatment option for patients with Merkel Cell Carcinoma that has spread within the body”, noted Adam Riker, MD, Professor, and Chief of Surgical Oncology at LSU Health New Orleans.
The clinical trials involved fifty patients with ages between 46 and 91 receiving Pembrolizumab intravenously every three weeks for up to two years. More than half of the participants experienced a response, 12 having a complete response while 16 other showing a partial reaction. On average, the length of progression-free survival was 26.8 months, with a 24-month rate of 48.3%. At 24 months, almost 70% of patients were still alive.
The trial concluded that “Pembrolizumab demonstrated durable tumor control, a generally manageable safety profile, and favorable OS [overall survival] compared with historical data from patients treated with first-line chemotherapy.”
Even though the disease is quite rare, the incidence of Merkel cell carcinoma increased by 95% between 2000 and 2013. The five-year overall survival rate ranges between 14% and 27% for advanced disease. UV exposure and a weak immune system are among the most important factors leading to the development of MCC.
As the disease often targets immunosuppressed hosts, researchers condidered it might be a suitable candidate for monoclonal antibody therapy. Pembrolizumab inhibits a protective mechanism of cancer cells and allows the immune system to destroy them. It targets the PD-1 pathway which is critical to the immune system’s ability to control cancer growth. The drug received FDA approval in 2017 for treating metastatic melanoma, but has extended its range of use since then to help fight several other cancer types.
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