Pembrolizumab Is Promising for Future Merkel Cell Cancer Treatment
For Merkel-cell cancers—the deadliest and rarest type—there are no approved drugs once surgery and radiation fail.
Over 5 million Americans are diagnosed with non-melanoma skin cancers each year, making them, collectively, the most commonly diagnosed types of cancer. But none of these cancers are tracked by cancer registries; they lack a separate funding category within the National Cancer Institute budget, and in the case of Merkel-cell cancers—the deadliest and rarest type—there are no approved drugs once surgery and radiation fail, according to the U.S. Food and Drug Administration (FDA).1,2
“Melanoma gets more attention probably because it affects younger people, so the societal cost may be higher, in terms of death,” Paul Nghiem, MD, PhD, professor of medicine, Division of Dermatology in the University of Washington's School of Medicine in Seattle, told Cancer Therapy Advisor. Dr Nghiem is also an affiliate investigator of the Clinical Research Division at Fred Hutchinson Cancer Research Center in Seattle, Washington.
Probably 150,000 of the 1 million squamous-cell cancers seen in the United States each year “behave badly and can kill a similar number of people as melanoma”--8800 annually compared with 10,130--he said.1 Immunocompromised patients are considered at the highest risk for complications and death.
Basal cell cancer, the most common form of non-melanoma skin cancer, causes disfigurement far more often than death, if left untreated.1
“There are always exceptions,” Dr Nghiem said, “but surgery almost always does the trick” to cure. In rare circumstances, however, these slow-growing cancers penetrate the outer layers of the skin and spread, and the first known effective treatment for locally advanced and metastatic disease became available only several years ago.3
In January 2012, the FDA approved vismodegib (Erivedge) for basal cell carcinoma, based on clinical trial results involving 104 patients published in The New England Journal of Medicine.4 A randomized companion trial with just 41 patients found that the drug also shrank and prevented tumors in patients with an inherited condition, known as basal cell nevus syndrome, which causes hundreds of these lesions to crop up all over the body.
In July of last year, the federal regulatory agency approved a second drug, sonidegib (Odomzo), for treating these common skin cancers that are no longer amenable to surgery or radiation. Its approval was tied to an ongoing multicenter clinical trial, in which patients were randomly assigned to receive either a high or low dose of the drug. The FDA approved the lower dose.5
Both drugs target the Hedgehog signaling pathway, a molecular driver behind more aggressive forms of the disease. But side effects have been severe,4,5 including muscle spasms and cramps, changes in taste, and hair loss, according to Thomas Olencki, DO, vice chairman of the Division of Medical Oncology at Ohio State University's James Cancer Hospital in Columbus. Dr Olencki is also a member of the National Comprehensive Cancer Network's committee on non-melanoma skin cancer, which sets guidelines for patient treatment nationwide. “These [side effects] are so frequent, many patients can't tolerate these drugs after surgery,” Dr Olencki told Cancer Therapy Advisor. “Most stop taking them,” and their cancers return.