Induction Immunotherapy Followed by Thoracic Radiation without Chemotherapy in Unresectable Stage III Non-Small Cell Lung Cancer: A Case Series

OBJECTIVE: Although concurrent chemoradiation has been the standard of care for unresectable stage III non-small cell lung cancer (NSCLC) due to increased survival and decreased disease progression, patients with poor performance status cannot tolerate chemotherapy toxicity well. Durvalumab, an immune checkpoint inhibitor targeting the programmed death receptor-1 (PD-1) / programmed death-ligand 1 (PD-L1) axis, demonstrated efficacy as maintenance therapy after definitive chemoradiation. However, the role of immunotherapy in those who cannot tolerate chemoradiation is unclear. METHODS: This retrospective case series reports adult patients with PD-L1-expressing stage III NSCLC diagnosed at Parkview Cancer Institute from 2019-2021 and treated initially with pembrolizumab followed by sequential consolidation chest radiation (CXRT) without cytotoxic chemotherapy. RESULTS: Four cases of stage IIIA squamous cell carcinoma were disease-controlled by this approach, with two partial and one complete response. One case of stage IIIC adenocarcinoma had progressive disease with brain metastasis prior to CXRT. CONCLUSION: This case series suggests that pembrolizumab with sequential CXRT may be beneficial for stage III NSCLC patients with high PD-L1 expression, but additional studies are needed to confirm this hypothesis.