Combination Immunotherapy With Radiotherapy in Non-Small Cell Lung Cancer: A Review of Evidence

Background

Radiotherapy plays a fundamental role in the treatment of patients with all stages of non-small-cell lung cancer (NSCLC). The emergence of immune checkpoint inhibitors (ICIs) has transformed the standard of care in these patients. The use of ICIs is increasingly utilized in the definitive setting as an adjunct to chemoradiotherapy or surgery and remains a vital component in the treatment of metastatic disease. Despite improvements in patient survival, the use of immunotherapy as monotherapy has shown limited overall response rates with susceptibility to resistance. Radiotherapy has been identified as a viable option to enhance the response rate to ICI and improve outcomes in NSCLC.

Methods

We queried the English PubMed database utilizing variably combined search items including “radiation,” “chemoradiation,” “immune checkpoint,” “immunotherapy,” “stereotactic body radiotherapy,” and “non-small-cell lung”. We additionally searched various acceptable alternative terms for similar keywords such as “radiotherapy” in place of “radiation.” These results were subsequently curated for relevance and impact on current treatment paradigms.

Results

In this review, we discuss preclinical and clinical studies relating to combinatorial use of immunotherapy and radiation in NSCLC. These studies are presented in the context of early-stage, operable stage III, unresectable stage III, and metastatic disease. The majority of the data illustrate promising results regarding the additive or synergistic effects of radiation and immunotherapy with a suggestion that the timing of these treatment modalities is crucial to optimizing outcomes.

Conclusion

While there is now evidence regarding the favorable interplay between radiation and immunotherapy in NSCLC, there remain multiple unanswered questions which are expected to be addressed in ongoing clinical trials.