Biologic therapy is a way to jump-start our immune system to fight cancer. Our body may not detect cancer cells and fight them. Biologic/immunotherapy can boost, direct, or restore our natural defenses against cancer. The main biologic drugs used in kidney cancer are cytokines. The cytokines used most often are interleukin-2 (IL-2) and interferon-alpha. Both of these treatments can shrink kidney tumors in a small percent of patients.