Pembrolizumab (Keytruda, Merck) can effectively shrink or eliminate tumors in patients with unresectable advanced desmoplastic melanoma, according to a new study in Nature Medicine.
Nearly 90% of participants experienced significant tumor reduction or complete disappearance after receiving pembrolizumab.
“Patients with advanced desmoplastic melanoma demonstrate a high response rate to single-agent PD-1 blockade therapy, reinforcing the use of anti-PD-1 as the preferred treatment option for this disease,” says study author Antoni Ribas, MD, a Professor of Medicine at the David Geffen School of Medicine at UCLA and Director of the UCLA Health Jonsson Comprehensive Cancer Center’s Tumor Immunology Program in Los Angeles, CA, in a news release. “It offers a less invasive, more targeted approach compared to surgery, radiation, or combination immunotherapies, which can have more severe side effects.”
SWOG S1512 Trial
Researchers launched the SWOG S1512 trial, conducted by the SWOG Cancer Research Network and funded by the National Cancer Institute (NCI). It was designed with two separate cohorts. Cohort A included patients with resectable desmoplastic melanoma treated with pembrolizumab before surgery.
This study focuses on the results from Cohort B.
Cohort B enrolled 27 patients whose desmoplastic melanoma had spread, or metastasized, and was considered to be inoperable. They received pembrolizumab infusions every three weeks for up to two years.
The team found that 37% of patients had a complete response, meaning their tumors completely disappeared. Overall, 89% of patients experienced tumor shrinkage or disappearance.
Importantly, the responses were often rapid, with some patients seeing tumor reduction within two months. Many maintained their remission long after stopping treatment. After three years, 84% of patients were still alive, and 72% showed no signs of cancer progression.
While the treatment was generally well-tolerated, many patients were older and had other health conditions, which caused some to experience side effects that led them to stop therapy early. Despite these early discontinuations, the treatment’s effectiveness did not appear to be reduced.
Promising Results
“The promising results from this trial show that pembrolizumab can offer durable benefit for patients with a melanoma subtype that previously had no successful treatment options, and now we know that desmoplastic melanoma is among the cancers with the highest response rates to the anti-PD-1 class of cancer immunotherapies,” adds Dr. Ribas, who is also Director of the Parker Institute for Cancer Immunotherapy Center at UCLA and member of the Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research at UCLA. “This advances our understanding of exceptional responders to cancer immunotherapy, and it changes the treatment paradigm with a highly active and low toxicity treatment approach.”
PHOTO CAPTION: Dr. Antoni Ribas, senior author of the study and director of the UCLA Health Jonsson Comprehensive Cancer Center’s Tumor Immunology Program, in his laboratory.
