Phase II clinical study evaluating the efficacy and safety of disitamab vedotin combined with sintilimab and S-1 in the conversion treatment of HER2-overexpression unresectable gastric cancer.

Abstract

TPS428 Background: Gastric cancer (GC) or gastroesophageal junction adenocarcinoma (GEJA) is the fifth commonest cancer and the fourth leading cause of cancer deaths worldwide. In about 30% to 40% of patients with advanced gastric cancer have lost the opportunity for radical surgery at the first diagnosis, and the overall 5-year survival rate is less than 50%. In recent years, conversion therapy has shown great promise. Disitamab vedotin is an antibody-drug conjugate comprising a novel HER2-directed monoclonal antibody, In previous study C008, RC48 showed a good safety profile and promising activity towards GC, and showed equivalent efficacy for HER2 IHC 2+ or HER2 IHC 3+ tumors. Methods: This study is a single-arm, phase II trial carry out at 16 academic hospitals in China, and will evaluate DV combined with Sintilimab and S-1 in patients with HER2-expressing unresectable gastric cancer. Eligible patients are at ≥ 18 to ≤ 75 years old; histologically confirmed, unresectable stage IV GC or GEJA; Single initial unresectable factor. For example, peritoneal metastasis (P1), Intraperitoneal free cancer cells positive (CY1), Paraaortic lymph node metastasis, liver metastasis (≤ 3 lesions, and ≤ 5 cm for a single lesion), ovarian metastasis; and documented histologically confirmed HER2 IHC 3+ or 2+; ECOG 0-1; at least one unresectable, measurable tumor lesion according to the RECIST version 1.1; adaptable function of the heart, liver, and kidney. 30 patients will be enrolled in this trial and receive Disitamab Vedotin(2.5mg/kg, IV, Q3W), Sintilimab (200 mg, IV, Q3W) and S-1 (twice daily on D1-14 are given at a dose calculate according to the body surface area and repeated every 3 weeks), until patients assessed by MDT to meet the criteria for surgical resection undergo gastrectomy. And the patients with peritoneal dissemination will combine with intraperitoneal administration of paclitaxel (60mg / m2, Q3W). The primary endpoint is R0 resection rate, Secondary endpoints include cORR, OS, RFS and safety. Seven patients have been enrolled in this study. Clinical trial information: NCT05627414 .