Oxaliplatin and capecitabine (XELOX) plus toripalimab as perioperative treatment for locally advanced gastric or gastro-esophageal junction adenocarcinoma (Neo-Capture): A single-arm, phase 2 study.

e16001 Background: PD-1 inhibitor combined with chemotherapy showed remarkable objective response rate in the first line treatment of metastatic gastric cancer. While, the benefit of perioperative PD-1 inhibitor plus chemotherapy in locally advanced gastric or gastro-esophageal junction (G/GEJ) cancer was not clear. Therefore, we aimed to assess the efficacy and safety of perioperative XELOX plus toripalimab in the patients with locally advanced G/GEJ cancer in this study. Methods: This was a prospective single arm phase 2 study. Eligible patients were with histologically confirmed locally advanced G/GEJ (Siewert II/II type) adenocarcinoma (cT3-4 Nany M0 or T1-2 N2-3 M0). Patients received 4 preoperative and 2 postoperative cycles of XELOX plus toripalimab (oxaliplatin 130mg/m2 D1, capecitabine 1000mg/m2 bid D1-14, toripalimab 240mg D1, Q3W) followed by subsequent 2 cycles of toripalimab monotherapy. Patients underwent D2 gastrectomy after preoperative treatment. The primary endpoint was major pathological response (MPR) according to Becker TRG criteria. Secondary endpoints included safety, R0 resection rate, pathological complete response (pCR), 3-year disease free survival (DFS) and 3-year overall survival (OS). Results: From Jul, 2019, to Dec, 2021, 35 pts were recruited. The median age was 61 (34-72) years old. 80% of the pts were men. Acutally, all the pts had cT4 (cT4a [48.6%] & cT4b [51.4%]) and 88.6% had cN+ by CT, MRI and ultrasound gastroscopy. 2 pts suffered disease progression during neoadjuvant treatment. 4 pts have not yet completed preoperative therapy. 29 pts had received gastrectomy and 2 pts were pathologically diagnosed with large cell neuroendocrine carcinoma. Therefore, 27 adenocarcinoma pts were included in this analysis. 3 (11.1%) pts achieved pCR (TRG1a) and 4 (14.8%) pts achieved MPR (TRG1a/b). R0 resection was achieved in 96.3% (26/27) of the pts. No patient had pT4b. The most common (≥10%) grade 1-2 treatment related adverse events (TRAEs) included leucopenia (45.7%), neutropenia (42.9%), thrombocytopenia (20%), nausea (34.1%), vomiting (14.3%), anorexia (14.3%), ALT increased (40%) and AST increased (34.3%). Only 4 (11.4%) pts experienced grade 3 neutropenia. No other ≥ grade 3 TRAEs occurred. Most of the potential immune-related adverse events were grade 1-2 including hypothyroidism (8.6%), adrenal insufficiency (2.9%) and hyperglycemia (11.4%). Only one (2.9%) patient had grade 3 hyperglycemia. No serious perioperative complication and death occurred. Conclusions: Perioperative XELOX plus toripalimab preliminarily showed a favorable R0 resection rate and acceptable MPR in cT4a/T4b locally advanced G/GEJ cancer patients with a manageable safety profile. Clinical trial information: NCT04119622.