Summary
This phase I/II trial studies the side effects and best dose of pralatrexate when given together with pembrolizumab and how well they work in treating patients with peripheral T-cell lymphomas that has come back after a period of improvement (relapsed) or has not responded to treatment (refractory). Pralatrexate may stop the growth of cancer cells by blocking some of the enzymes needed for cell growth. Immunotherapy with monoclonal antibodies, such as pembrolizumab, may help the body’s immune system attack the cancer, and may interfere with the ability of tumor cells to grow and spread. Giving pembrolizumab and pralatrexate may work better in treating patients with peripheral T-cell lymphomas.