Immunotherapy, particularly immune-checkpoint inhibition, is producing encouraging clinical responses and affecting the way numerous cancers are treated. Yet immune-checkpoint therapy is not effective for many patients, and even those who initially respond can experience relapse, fueling interest in finding new processes or tools to improve the effectiveness of these novel therapeutics. One such tool is radiation. Both preclinical and clinical studies have demonstrated that the systemic effects of immunotherapy can be amplified when it is used in combination with radiation and, conversely, that the immunogenic effects of local irradiation can be amplified and extended to distant sites when used with immunotherapy. We review how stereotactic ablative radiation therapy, a technique specifically indicated for tumors treated with immune-checkpoint inhibitors, can potentiate the effects of immune-checkpoint therapy. We further explore how these novel therapeutics may transform radiation, previously considered a local treatment option, into powerful systemic therapy.
From the *Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY; Departments of †Experimental Radiation Oncology and ‡Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX; and Departments of §Dermatology and ∥Pathology, Yale University School of Medicine, New Haven, CT.
Supported in part by Cancer Center Support (Core) grant CA016672 from the National Cancer Institute; National Institutes of Health grant to The University of Texas MD Anderson Cancer Center; The family of M. Adnan Hamed; The Mabuchi Research Fund; The Susan and Peter Goodwin Foundation; and the Orr Family Foundation to MD Anderson Cancer Center’s Thoracic Radiation Oncology Program, an MD Anderson Knowledge Gap Award.
The authors have disclosed that they have no significant relationships with, or financial interest in, any commercial companies pertaining to this article.
Reprints: James W. Welsh, MD, Department of Radiation Oncology, Unit 97, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd, Houston, TX 77030. E-mail: firstname.lastname@example.org.