Clinical Trials Integrating Immunotherapy and Radiation for Non-Small-Cell Lung Cancer

Methods of harnessing the immune system to treat cancer have been investigated for decades, but yielded little clinical progress. However, in recent years, novel drugs that allow immune recognition and destruction of tumor cells are emerging as potent cancer therapies. Building upon previous immunotherapy strategies that included therapeutic vaccines, recombinant cytokines, and other immunostimulatory agents, newer immunotherapy agents targeting immune checkpoints including programmed cell death 1, programmed cell death ligand-1, and cytotoxic T-lymphocyte-associated protein 4, among others, have garnered substantial enthusiasm after demonstrating clinical activity in a broad spectrum of tumor types. Trials evaluating immune checkpoint inhibitors in metastatic non-small-cell lung cancer (NSCLC) demonstrate robust and durable responses in a subset of patients. However, with overall response rates less than 20%, combinatorial strategies that extend the benefit of these agents to more patients are desirable. The integration of radiotherapy with immunotherapy is a conceptually promising strategy, as radiotherapy has potent immunomodulatory effects and may contribute not only to local control but may also augment systemic antitumor immune response. Preclinical data and case reports suggest the potential for robust clinical responses in metastatic NSCLC patients using this strategy, but prospective clinical trials evaluating the integration of radiation and immunotherapy are limited. The use of immunotherapy in nonmetastatic settings is also intriguing but understudied. We review the potential clinical settings of interest for the partnering of immunotherapy and radiation in NSCLC, including early stage, locally advanced, and metastatic disease, and review completed, accruing, and developing clinical trials.