Evaluating the safety and effectiveness of pembrolizumab in combination with rituximab in patients with relapsed or refractory follicular lymphoma.

This study evaluated the safety and effectiveness of pembrolizumab (Keytruda) in combination with rituximab (Rituxan) in patients with relapsed or refractory (r/r) follicular lymphoma (FL). The data showed that pembrolizumab in combination with rituximab was safe and effective in these patients.

Follicular lymphoma (FL) is a type of non-Hodgkin lymphoma (NHL). It affects white blood cells called B-lymphocytes. These cells normally fight infection in the body. It is commonly a slow-growing cancer. FL that has relapsed (worsening of the disease) or refractory (not responded to the treatment) is more difficult to treat.

Rituximab is commonly used in the treatment of FL. Rituximab is an immune protein that works by helping the body’s immune system attack cancer cells. Pembrolizumab is an immunotherapy that helps the immune system detect and kill cancer cells. Some cancer cells have on their surface proteins, such as PD-L1 that bind to PD-1 protein which helps them avoid detection from the immune system. Pembrolizumab blocks the PD-1 protein, and this inhibition triggers the immune system to attack tumor cells and kills them. The safety and effectiveness of pembrolizumab in combination with rituximab in patients with r/r FL are still unknown.

This study involved 30 patients with r/r FL. All patients received pembrolizumab (200 mg) every 3 weeks for up to 16 cycles in combination with rituximab (375 mg/m²) for 4 weeks. The average follow-up time was 34.9 months.

17% of the patients experienced serious treatment-related side effects. The most common serious side effects were liver enzyme abnormalities (3%), diarrhea (3%), nausea (3%), inflammation of the linings of the brain (3%), and inflammation of the pancreas (3%). Treatment-related side effects led to the stopping of treatment in 20% of the patients.

13% of the patients experienced serious immune-related side effects. The most common immune-related side effects were diarrhea (43%), liver enzyme abnormalities (33%), thyroid dysfunction (27%), and rash (23%).

Overall, 67% of the patients responded to the treatment. The complete response (complete disappearance of cancer) rate was 50%. The partial response (partial disappearance of the cancer) rate was 17%.

For patients who responded to treatment, the response lasted on average 17.5 months. The average survival without cancer worsening was 12.6 months. After 3 years, 97% of the patients were alive and 23% of patients were in remission.

This study concluded that pembrolizumab in combination with rituximab was safe and effective in patients with r/r FL.

This study had a small number of participants. There was no comparison group. Future randomized studies evaluating the safety and effectiveness of pembrolizumab in combination with rituximab versus rituximab alone are necessary.