CATALYST is a resource center and information hub for clinicians and patients with cancer, providing accurate and up-to-date information on current and emerging immunotherapies. Immunotherapy is revolutionizing the way cancer is treated, yielding unprecedented responses and survival benefits for patients with difficult-to-treat solid tumors and hematologic cancers. The goal of the CATALYST initiative is to provide a better understanding of how immunotherapies can be used to unleash the immune system’s natural ability to fight cancer. In the Clinical Care Toolkit, you will find information on how the immune system is regulated, the mechanisms of action of current and emerging immune checkpoint inhibitors, and links to additional resources. The Patient Toolkit provides advice on living with cancer and answers to frequently asked questions.