Neoadjuvant SHR-1701 (a bifunctional anti-PD-L1/TGF-βRII agent) combined with chemoradiotherapy for resectable locally advanced esophageal squamous cell carcinoma (ESCC): A phase II trial.

410 Background: Neoadjuvant chemotherapy or chemoradiotherapy followed by surgery is the standard of care for resectable locally advanced ESCC. SHR-1701, a new bifunctional fusion protein composed of a monoclonal antibody against PD-L1 fused with the extracellular domain of TGF-β receptor II, may enhance antitumor activity in combination with neoadjuvant standard therapies in ESCC patients (pts). The aim of this phase II trial is to determine the safety and efficacy of neoadjuvant chemoradiotherapy plus SHR-1701 followed by esophagectomy in pts with locally advanced resectable ESCC. Methods: Pts with resectable thoracic ESCC, diagnosed as clinical stage of cT1b-cT2N+M0 or cT3-cT4aNxM0 per AJCC 8th were eligible. Preoperative therapy included SHR-1701 (30 mg/kg every 3 weeks for 2 cycles), albumin paclitaxel (50 mg/m 2 , once a week for 5 weeks), carboplatin (AUC=2, once a week for 5 weeks) and radiotherapy (41.4Gy in 23 fractions). Following esophagectomy, pts received SHR-1701 up to 1 year. The primary endpoint was pathological complete response (pCR) rate in the per-protocol population. Secondary endpoints included R0 resection rate, major pathological response (MPR) rate, disease free survival (DFS) and safety. Results: Between Dec. 2021 and Feb. 2023, 43 pts were screened and 41 met the inclusion criteria, among whom the clinical stage I, II, III, and IVa at baseline were 1 (2.4%), 8 (19.5%), 31 (75.6%), and 1 (2.4%), respectively. All 41 pts received neoadjuvant SHR-1701 combined with chemoradiotherapy. As of Mar. 2024, 30 pts underwent surgery, and all achieved R0 resection. There was no in-hospital and postoperative 30-day mortality. 9 (30.0%) pts achieved pCR in both primary tumor and lymph nodes (ypT0N0), and 12 (40.0%) pts had complete pathological response of the primary tumor with residual disease in lymph nodes alone (ypT0N+). Treatment-related adverse events (TRAEs) occurred in all pts, and most of TRAEs were grade 1-2. Notable toxicity included pneumonitis (31.7%) and anastomotic leak (12.2%). Conclusions: The addition of SHR-1701 to neoadjuvant chemoradiotherapy in ESCC demonstrated promising efficacy with acceptable toxicity, and might be a promising approach for neoadjuvant treatment. Clinical trial information: ChiCTR2000041562.