Safety and feasibility of esophagectomy following neoadjuvant immunotherapy combined with chemotherapy or chemoradiotherapy for locally advanced esophageal squamous cell carcinoma: Analysis of two phase 2 clinical trials.

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4070 Background: Despite the survival benefit of preoperative chemotherapy (CT) or chemoradiotherapy (CRT) in patients with locally advanced esophageal squamous cell carcinoma (ESCC), the prognosis remains dismal. With the potential benefit of combining immune checkpoint inhibitors (ICIs) neoadjuvantly, we initiated two phase II single-armed clinical trials to explore the efficacy, feasibility, and safety of esophagectomy following the combination of preoperative PD-1 inhibitor with CT or CRT in ESCC. Methods: A total of 55 patients with histologically confirmed ESCC (clinical stage II-IVA according to the American Joint Committee on Cancer 8th staging system) from two phase 2, single-arm trials underwent neoadjuvant ICIs combined with chemotherapy (nICT) (n=38) (NCT04506138) or chemoradiotherapy (nICRT) (n=17) (NCT03940001) between May 2019 and June 2022 were enrolled. Patients received 2 doses of intravenous PD-1 inhibitor every 3 weeks, combined with 2 cycles of CT or CRT. Data on the pathological complete response (pCR) rates, operative time, blood loss volume, 30-day complications, hospital stay, and 30-day mortality were collected and assessed between these two groups using a multivariable log-binomial regression model to obtain adjusted relative risk ratios. The primary endpoints of the studies were the safety and feasibility of esophagectomy after the combination of preoperative CT or CRT and PD-1 inhibitor. We also evaluated pCR, primary tumor pCR, operation time, postoperative stay, and 30-day mortality. Results: All the included patients successfully completed neoadjuvant therapy. Age, sex, performance status, clinical stage, histologic subtype, procedure type, operative time, and blood loss volume were similar between the two groups. The primary tumor pCR rates were 52.9% in the nICRT group and 21.6% in the nICT group, respectively (p=0.03), while the postoperative pCR rates were 41.2% in the nICRT group and 21.6% in the nICT group, respectively (p=0.19). Minimally invasive surgery was performed in 89.2% (33/37) of the nICT group and 94.1% (16/17) of the nICRT group. The risk of developing pulmonary, anastomotic, or other complications was similar in the two groups. Conclusions: Esophagectomy was safe after the addition of PD-1 inhibitor to preoperative CT or CRT in ESCC neoadjuvant therapies. Follow-up and exploratory endpoints, including biomarker analyses are ongoing. Clinical trial information: NCT03940001 ; NCT04506138 .