In a recently published study, it was shown that more than two-thirds of people with a rare type of melanoma, Desmoplastic Melanoma, responded to treatment with anti-PD-1 immunotherapies.
Desmoplastic melanoma, an uncommon subtype of melanoma, has proven itself to be highly resistant to more traditional treatment approaches, like chemotherapy, radiation, and surgery. It is thought that Desmoplastic Melanoma tumors have very dense tissue which limits the ability of the immune cells to infiltrate and attack the cancer. They are also characterized by a lack of “driver” mutations, which are required for drug development and personalized medicine strategies. These factors had previously led physicians to believe that people with Desmoplastic Melanoma as well as other dense cancers to be unlikely to benefit from immunotherapy.
In the study, researchers at UCLA hypothesized that despite the very dense tissue associated with Desmoplastic Melanoma tumors, patients may still respond well to anti-PD-1 or anti-PD-L1 therapies. They also sought to understand how DNA damage from ultraviolet light (which is a common result of sun exposure and highly associated with Desmoplastic Melanoma) and PD-L1 expression levels in tumor cells affect patient response to immunotherapy.
They evaluated 60 people with advanced Desmoplastic Melanoma who had received anti-PD-1 or anti-PD-L1 therapies over a five-year period. The researchers found that 70 percent of the evaluated patients, or 42 out of 60, had a reduction in tumor size that was sustained over many months or years. Also, cancer was no longer detectable in 19 of these 42 people, and none of those 19 individuals had a recurrence of the disease to date.
Even though Desmoplastic Melanomas only account for only 4 percent of all melanomas, the current survival rates are poor, so there is an urgent unmet need for new treatment strategies for this disease. The good news is that the findings of this study have led to a new clinical trial in more than 100 sites across the United States sponsored by the National Cancer Institute, offering the anti-PD-1 therapy pembrolizumab (commercialized as Keytruda) to people with Desmoplastic Melanoma even before they undergo surgery.
High response rate to PD-1 blockade in desmoplastic melanomas. Nature, 2018; DOI: 10.1038/nature25187
Joel T. Nowak, MA, MSW wrote this Post. Joel is the CEO/Executive Director of Cancer ABCs. He is a Cancer Thriver diagnosed with five primary cancers - Thyroid, Metastatic Prostate, Renal, Melanoma, and the rare cancer Appendiceal cancer.
