Phase II study of perioperative toripalimab in combination with FLOT in patients with locally advanced resectable gastric/gastroesophageal junction (GEJ) adenocarcinoma.
Authors: Hongli Li, Jingyu Deng, Shaohua Ge, Fenglin Zang, Le Zhang, Peng Ren, Baogui Wang, Fuliang Cao, Ting Deng, Rui Liu, Tao Ning, Yuchong Yang, Ming Bai, Xia Wang, Zhi Ji, Jingjing Duan, Yong Liu, Dejun Zhou, Han Liang, Yi Ba
Journal: Journal of Clinical Oncology (2021)

4050 Background: FLOT is the standard perioperative treatment for resectable gastric /gastroesophageal junction (GEJ) adenocarcinoma. However, patient’s outcome is still poor. Toripalimab, a humanized IgG4 monoclonal antibody against programmed cell death receptor-1 (PD-1), has shown remarkable clinical efficacy in various cancers. This trial evaluates the addition of Toripalimab to FLOT for resectable patients. Methods: This is a prospective, single-arm, investigator-initiated phase II trial. Patients with histologically confirmed, resectable, gastric and GEJ adenocarcinoma (≥cT2 or cN+) were enrolled to receive 4 pre-and post-operative cycles of toripalimab (240mg, q2w) plus FLOT (docetaxel 50 mg/m2; oxaliplatin 85 mg/m2; leucovorin 200 mg/m2; 5-FU 2600 mg/m2, q2w). The primary endpoint was pathological complete response rate (pCR). The secondary endpoints included major pathological (complete and nearly complete) response (MPR), and R0-resection rate, 3-year disease-free survival rate, overall survival, and adverse events. Results: In total, of 36 patients were enrolled from June 2019 through Dec 2020. Male, 66.7%; median age, 60y; cT3 8.3%, T4, 83.3%; cN+ 88.9%; GEJ 47%; MSI-H, 5.6%, Her-2neu-positive, 5.6%, EBER-positive, 5.6%). Two patients refused surgery, six patients have not yet completely neoadjuvant treatment. 100% of patients completed the 4 pre-cycle. Patients who had received gastrectomy after neoadjuvant treatment (n=28) were included in this analysis. 6 (21%) patients had operations involving a thoracic approach (oesophagogastrectomy with two field lymphadenectomy), 21 (75%) gastrectomy with D2 lymphadenectomy. 8 (29%) evaluable patients had Clavien-Dindo grade II post-operative complications and 2 (7%) grade IIIA complications; one patient had an anastomotic leakage that was treated endoscopically. There were no emergency re-operations. All 28 patients achieved R0-resection and were discharged home after a median of 12 days (range:7-63) in hospital. 7 （25%）patients achieved pCR (TRG1a) and 12 (42.9%) patients achieved major pathologic response (MPR, TRG1a/b). Treatment-related adverse events (TRAEs) to any drug were reported in 30 (94%) patients. Mostly TRAEs were grade 1-2, the grade 3 or 4 TRAEs included neutropenia (34%), neutropenia (25%), lymphopenia (3%), Alanine aminotransferase increased (3%), hypokalemia (3%) and anaemia (3%). Conclusions: Perioperative toripalimab in combination with FLOT showed promising efficacy with high pCR and MPR rate and well tolerated safety profile in patients with resectable gastric/GEJ adenocarcinoma. This combination regimen might present a new option for patients with locally advanced, resectable gastric/GEJ adenocarcinoma. Clinical trial information: NCT04354662.