Induction Anti-PD-1 Immunotherapy plus Chemotherapy Followed by Definitive Chemoradiation Therapy in Locally Advanced Esophageal Squamous Cell Carcinoma: A Real-World Retrospective Study

Abstract

<h3>Purpose/Objective(s)</h3> The addition of immunotherapy to chemotherapy significantly improved survival in patients with advanced or metastatic esophageal squamous cell carcinoma (ESCC). Neoadjuvant immunotherapy plus chemotherapy was safe and effective in locally advanced resectable ESCC. However, little is known about its role in the induction setting before chemoradiation therapy in unresectable locally advanced ESCC. This study evaluated the efficacy of induction anti-PD-1 immunotherapy plus chemotherapy followed by definitive chemoradiation therapy (dCRT) in locally advanced ESCC. <h3>Materials/Methods</h3> Patient and treatment characteristics were collected on all consecutive locally advanced ESCC patients from November 2017 to December 2021 at our institution who were treated with dCRT, with or without induction anti-PD-1 immunotherapy plus chemotherapy. We compared progression free survival (PFS) and overall survival (OS) between the treatment groups by using the Kaplan-Meier method and Cox proportional hazards regression. <h3>Results</h3> In a total of 137 unresectable locally advanced ESCC patients who completed the treatment of dCRT, 62 (45.3%) of whom underwent induction anti-PD-1 immunotherapy plus chemotherapy before dCRT, and 75 (54.7%) of whom underwent dCRT only. Overall, with a median follow-up of 19.0 months (range, 4.2-59.3 months) for survivors, the median PFS and OS were 20.0 and 30.4 months, respectively. Patients with locally advanced ESCC who received induction anti-PD-1 immunotherapy plus chemotherapy before dCRT had a marginally longer PFS than those who received dCRT alone (28.8 vs. 15.9 months; hazard ratio 0.68, 95% CI 0.42-1.11; P = 0.128), with the 1-year PFS rate of 72.6% and 60.0%, respectively. The median OS of the patients who received induction anti-PD-1 immunotherapy plus chemotherapy before dCRT and those who received dCRT alone were not reached and 25.2 months, with the 1-year OS rate of 85% and 81.3%, respectively (hazard ratio 0.57, 95% CI 0.32-1.01; P = 0.058). <h3>Conclusion</h3> Compared with dCRT alone, induction anti-PD-1 immunotherapy plus chemotherapy followed by dCRT yields more favorable survival outcomes in patients with unresectable locally advanced ESCC. More prospective clinical studies should be warranted.