520. EFFICACY AND SAFETY OF NEOADJUVANT CHEMOTHERAPY AND IMMUNOTHERAPY IN LOCALLY RESECTABLE ADVANCED ESOPHAGEAL SQUAMOUS CELL CARCINOMA

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Abstract Compared with neoadjuvant chemotherapy, concurrent chemoradiotherapy can significantly increase pCR rate and improve overall survival of Locally Advanced ESCC. However, the major pattern of failure is distant metastasis, and the increased risk of adverse events and surgery. Adding PD-1 inhibitor to the chemotherapy have shown significant clinical benefits and become the standard of care for first-line treatment of ESCC. We investigate the efficacy and safety of neoadjuvant PD-1 blockade combined with chemotherapy in real world. We performed a retrospective, single institution review of all resectable locally advanced ESCC patients who received neoadjuvant sintilimab combined with chemotherapy and completed surgery in the sixth medical center of PLA general hospital from December 2019 to February 2022. The primary outcome was pCR rate in both the primary tumor and lymph nodes. Secondary outcomes were R0 resection rate, MPR rate, tumor downstaging rate, surgical complications, and treatment-related adverse events (TRAEs). 37 Patients aged between 47 to 76 years old (median age, 62) were collected. 3(8.1%) were diagnosed with stage II ESCC, 30(81.1%) with stage III, and 7(18.9%) with stage IVA (AJCC 8th). 30(81.1%) were male. 31 patients received 2 cycles and 6 patients received 3 cycles. 5(13.5%) patients obtained pCR. 7(18.9%) patients obtained pCR in primary tumor. 36(97.3%) patients obtained R0 resection. MPR (PCR included) was achieved in 18 (48.6%) patients. 28(75.7%) patients achieved clinical downstaging, and 64.9 (%) achieved pathological downstaging. Grade 3-4 TRAEs occurred in 7(18.9%) patients, and grade 3-4 surgical complications occurred in 1(2.7%) patient. These real-world data revealed that neoadjuvant sintilimab plus chemotherapy could provide benefits with good tolerability for resectable locally advanced ESCC, and warrants further exploration in prospective clinical studies.