High Grade Astrocytic Tumor

This phase II trial tests the safety and side effects of efineptakin alfa and pembrolizumab in treating patients with glioblastoma that has come back (recurrent). Efineptakin alfa is an immunotherapy drug that works by helping the immune system fight tumor cells. 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 efineptakin alfa and pembrolizumab may kill more tumor cells in patients with recurrent glioblastoma.