Evaluating the effectiveness and safety of pembrolizumab given after surgery in patients with stage II melanoma.

This study evaluated the effectiveness and safety of pembrolizumab (Keytruda) given after surgery in patients with stage II melanoma. The data showed that pembrolizumab given after surgery for up to 1 year significantly reduced the risk of cancer recurrence or death in these patients.

Melanoma is one of the most aggressive forms of skin cancer. Treatment for melanoma includes surgery to remove the tumor. In some patients, the tumor can come back after surgery (recurrence). In more advanced melanoma, the tumor can spread to other parts of the body (metastasis). In patients with more advanced stage melanoma, the risk of recurrence or metastasis is higher.

To avoid this, patients can be given additional therapy after surgery (adjuvant treatment). Immunotherapy uses the body’s own immune system to fight cancer. PD-L1 is a protein that can be found in high numbers on cancer cells. These proteins can stop the immune system from killing cancerous cells. Pembrolizumab is an example of PD-1 inhibitor that works by inhibiting (blocking) PD-L1. This inhibition triggers the immune system to attack tumor cells and kill them. Previous study showed that pembrolizumab given after surgery improves survival outcomes in patients with stage III melanoma. However, the effectiveness and safety of pembrolizumab given after surgery in patients with stage II melanoma is not known yet.

This study involved 976 patients with stage II melanoma. Patients were randomly assigned into 2 groups. 487 patients received pembrolizumab. 489 patients received a placebo. Patients were followed-up twice- first after 14.4 months and second after 20.9 months.

After 12 months, 90% of the patients in the pembrolizumab group were alive without cancer recurring compared to 83% of the patients in the placebo group. Patients in the pembrolizumab group were 36% more likely to survive without cancer recurring compared to patients in the placebo group.

After 18 months, 86% of the patients in the pembrolizumab group were alive without cancer recurring compared to 77% of the patients in the placebo group. Patients in the pembrolizumab group were 40% more likely to survive without cancer recurring compared to patients in the placebo group.

16% of the patients in the pembrolizumab group experienced serious side effects compared to 4% of the patients in the placebo group. Most side effects involved thyroid gland dysfunction.

This study concluded that pembrolizumab given after surgery for up to 1 year significantly reduced the risk of cancer recurrence or death, with manageable side effects, in patients with stage II melanoma.

This study was funded by Merck, the manufacturer of pembrolizumab.