One Dose of Pembrolizumab Before Melanoma Surgery Can Put Patients in Remission

Peak Immune Responses Occur as Early as Seven Days After Treatment

A single dose of a PD-1 inhibitor prior to surgery for melanoma can put patients in remission. Researchers from the Abramson Cancer Center at the University of Pennsylvania recorded the finding in the largest group of patients to be treated with anti-PD-1 drugs pre-surgery.  

The study also showed that immune responses brought about by the therapy can peak as soon as seven days after treatment, which is much earlier than previous studies demonstrated. Participants completed up to a year of anti-PD-1 therapy after surgery, and those with complete responses after the initial dose have remained cancer free for more than two years.

In patients whose melanoma returns after surgery, tumor mutations such as B2M or TP53 and an increased activity of cells that naturally suppress the immune system enable the returning cells to adapt and develop resistance to PD-1 inhibitors. The finding could enable researchers to predict the cancer’s next step.

Melanoma is the deadliest form of skin cancer. The American Cancer Society estimates more than 96,000 new melanomas will be diagnosed in the U.S. in 2019, and around 7,200 people are expected to die from the disease this year.

Researchers gave 27 patients one dose of pembrolizumab three weeks before surgery. Eight (30 percent) had a complete response or major response (< 10% of cancer cells remained at time of surgery.) All eight patients continue to be disease-free at a median follow-up of 25 months.

Researcher say the focus of future studies will be on altering post-surgical therapies based on pre-surgical responses.

MedicalXpress, February 25, 2019