024. CONVERSION ESOPHAGECTOMY FOLLOWING IMMUNOCHEMOTHERAPY IN UNRESECTABLE ESOPHAGEAL SQUAMOUS CELL CARCINOMA: A SINGLE-CENTER, PROSPECTIVE STUDY

Abstract Background Esophageal squamous cell carcinoma (ESCC) presents a considerable clinical challenge, particularly in cases deemed unresectable due to cT4b tumors or bulky lymphadenopathy. Traditional treatment modalities predominantly consist of radical chemoradiotherapy. The USE-1 study aims to evaluate the clinical efficacy and safety of conversion therapy that combines chemotherapy and immunotherapy to potentially convert unresectable ESCC to a resectable state. Methods Preoperative therapy comprised sintilimab, nab-paclitaxel, and cisplatin administered every three weeks for 2–4 cycles. Following two cycles of immunochemotherapy, the initial efficacy evaluation was conducted; Patients receiving four cycles of immunochemotherapy who did not meet the criteria for esophagectomy were excluded from the study. Surgery was conducted 3–6 weeks after the completion of the preoperative therapy. The primary endpoint was the conversion rate, while secondary endpoints included R0 resection rate, pathologic complete response (pCR) rate, major pathological response (MPR) rate, perioperative complications and recurrence-free survival (RFS), overall survival (OS). Results 25 qualifying patients had been enrolled (17 with cT4b tumors and 8 with bulky lymphadenopathy). Esophagoaortic fistula occurred in 1 case, and esophagotracheal/esophagobronchial fistula occurred in 2 cases. Ultimately, 14 patients underwent thoraco-laparoscopic esophagectomy without intraoperative conversion to open surgery (9 with cT4b tumors and 5 with bulky lymphadenopathy). R0 resection was achieved in 64.3% of these patients (9/14), with pCR and mPR rates of 28.6% (4/14) and 14.3% (2/14), respectively. No postoperative deaths were reported. The median follow-up time was 13.2 months (0.9–22.4 months), with a median PFS of 9.2 months and a median OS of 11.3 months. Conclusion Esophagectomy following conversion immunochemotherapy appears to be a promising radical treatment for unresectable esophageal squamous cell carcinoma. The conversion rate was 56% (14/25), with R0 resection achieved in 64.3% (9/14) of patients. Long-term follow-up results are necessary for further elucidation of the treatment’s efficacy.