Pembrolizumab shows improved long-term survival after removal of stage III melanoma

This study presents updated longer-term data on recurrence-free survival (RFS) for pembrolizumab (Keytruda) after surgery for stage 3 melanoma.

The study showed that pembrolizumab has a lasting and improving effect on RFS as a treatment after surgery.

For patients with stage 3 melanoma, where lymph nodes might be affected, removal surgery (resection) is often a first step of the treatment. This is where cancer and possibly lymph nodes are removed. After this initial treatment, additional therapy (adjuvant therapy) is applied in most cases. Pembrolizumab is an immunotherapy that blocks proteins such as PD-L1 or PD-L2 that can be found on cancer cells. By blocking these proteins, it activates the immune system to fight cancer.

RFS of pembrolizumab after surgery for stage 3 melanoma was previously investigated with an average follow-up time of 1.25 years. The results of this study led to the approval of pembrolizumab in Europe and in the US. The RFS for a longer follow-up time is still unclear.

This study included 1019 patients with stage 3 melanoma who all underwent tumor and lymph node resection. They were randomly placed into two groups. 505 patients received a placebo, 514 received 200mg pembrolizumab every 3 weeks for 1 year. The average follow-up time was 3.05 years.

In the placebo group, 2.2% withdrew because of side effects compared to 14.1% in the pembrolizumab group. Withdrawal because of a return of the cancer was reported in 21.4% of the pembrolizumab group compared to 35.7% in the placebo group.

The RFS rate at 3 years for the pembrolizumab group was significantly longer (63.7%) compared to the placebo group (44.1%). Patients being treated with pembrolizumab had a 44% lower risk of a return of cancer compared to placebo. 

In patients with PD-L1 positive tumors (the PD-L1 protein is present on cancer cells), pembrolizumab was also associated with a 43% lower risk of cancer recurrence compared to placebo.

The study concluded that pembrolizumab after surgery improves survival without recurrence in patients with stage 3 melanoma.

That this study was financially supported by Merck & Co, the manufacturer of pembrolizumab.