Initial results for Pembrolizumab as first line treatment for a rare but threatening form of skin cancer known as Merkel cell carcinoma show improved responses and longer survival than expected with conventional chemotherapy. The study involved researchers at the Bloomberg~Kimmel Institute collaborating with investigators from the Fred Hutchinson Cancer Research Center in Seattle, along with 11 other U.S. medical centers.
“Immunotherapy provides an effective treatment for patients with Merkel cell carcinoma who before had few options. Immunotherapy is unique in cancer treatment, because it does not directly target cancer cells but rather removes constraints on the immune system’s natural ability to find and destroy cancer cells”, explained Suzanne Topalian, M.D, one of the co-authors.
These findings come to support the recent accelerated approval designation awarded by the FDA.
50 patients participated in the study for Pembrolizumab as initial treatment for patients with recurrent, locally advanced or metastatic Merkel cell carcinoma. More than half (28 patients) experienced long-lasting responses to the treatment, 12 of whom showing a complete disappearance of their tumors. Nearly 70 percent of patients in this study were alive two years after starting treatment.
“This is the earliest trial of immunotherapy as a front-line therapy for Merkel cell carcinoma, and it was shown to be more effective than what would be expected from traditional therapies, like chemotherapy”, noted Dr. Topalian.
Merkel cell carcinoma is classified as an “orphan disease”, having fewer than 2,000 diagnoses annually in the United States. Patients are typically over the age of 70 and often present suppressed immune systems. In most cases, the diseases are caused by a virus called Merkel cell polyomavirus.
Pembrolizumab therapy was effective against both virus-positive and virus-negative Merkel cell carcinomas, offering high response rates and durable progression-free survival in both subtypes. Furthermore, tumors expressing a PD-1-related protein tended to have a longer reaction to treatment.
“These findings could be a precursor to developing more effective treatments for other virus-related cancers, which account for about 20 percent of cancers worldwide”, added William Sharfman, M.D., Professor of Cancer Immunology and Melanoma Research.
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