NCT06059495

Watch-and-Wait Approach With Dostarlimab in Localized dMMR/MSI-H Gastric Cancer: GERCOR Phase II Study

Watch-and-wait Strategy to Initiate Dostarlimab-based Immunotherapy in Localized Deficient Mismatch Repair (dMMR) and/or Microsatellite Instability High (MSI-H) oEso-gastric Junction and Gastric Adenocarcinoma: An Open-label GERCOR Phase II Study

• Status: Recruiting
• Phase: Phase 2
• Study type: Interventional
• Enrollment: 59 (estimated)
• Sponsor: GERCOR - Multidisciplinary Oncology Cooperative Group · Academic / Other
• Sex: All
• Age: 18 Years – 75 Years
• Healthy volunteers: Not accepted

Summary

This phase II study will evaluate dostarlimab with a watch-and-wait approach for patients with localized mismatch repair deficiency (dMMR)/microsatellite instability (MSI) gastric or oeso-gastric junction adenocarcinoma. The goal of the study is to determine whether the surgery could be avoided in patients with localized dMMR/MSI-H gastric/OGJ adenocarcinoma with complete response at endoscopy and biopsies free of tumoral cells after treatment with dostarlimab, with a watch-and-wait approaches.

Detailed description

In patients with localized, resectable gastric or oeso-gastric junction (OGJ) adenocarcinoma radical surgery is the only curative option. Despite the evolution in treatment with multimodality strategies, gastric or OGJ adenocarcinoma remains one of the most lethal malignancies. When the disease is localized, perioperative chemotherapy with cytotoxic agents is the preferred strategy. The morbidity rate associated with oesophagogastrectomy/gastrectomy and their negative impact on patients' quality of life and considering the high efficacy of ICIs in patients with localized tumor, one might wonder whether the surgery could be avoided in patients with localized dMMR/MSI-H gastric/OGJ adenocarcinoma The purpose of this national, multicenter, open-label phase II study is to look at the effects of the immunotherapy drug dostarlimab with a watch-and-wait approach in patients with localized dMMR/MSI gastric or oeso-gastric junction adenocarcinoma and to determine whether patients with complete response at endoscopy and biopsies free of tumoral cells after treatment with dostarlimab, with a watch-and-wait approach can circumvent surgical resection. The primary objective of the study is the rate of complete clinical response at 1 year. A total of 59 patients are expected to be enrolled in the study. Patients will be included in participating centers, which will perform treatments.

Conditions

• Adenocarcinoma - GEJ
• Gastric Adenocarcinoma

Interventions

Type	Name	Description
DRUG	Dostarlimab	After inclusion: dostarlimab 500mg IV 30min q3w (± 2-3 days) for 4 cycles (C1-C4) Then: At wk12 • If cCR: dostarlimab 1000mg q6w for 2 cycles (C5-C6) • If downstaging at UGI endoscopy, and no disease progression (PD)/or mets on TAP-CT, \<3 biopsies with tumor cells: dostarlimab 500mg q3w for 4 cycles (C5-C8) • If loco/loco-regional PD on TAP-CT, macroscopic tumor on UGI endoscopy, no distant mets, and \>2 positive biopsies at wk12 followed by surgery and if Becker-TRG 1a, 1b, or 2 after surgery: dostarlimab 1000mg q6w for 6 cycles (C5-C10) At 24wk • If cCR at 12 and 24 wks: dostarlimab 1000mg q6w for 4 cycles (C7-C10) • If downstaging at UGI endoscopy without PD on CT at wk 12 with \<3 biopsies with tumor cells at wk12 and cCR: dostarlimab 1000mg q6w for 4 cycles (C9-C12) • If downstaging at UGI endoscopy without PD on CT at wk 12 with and no cCR, surgery will be proposed and if Becker-TRG 1a, 1b, or 2 after surgery: dostarlimab 1000mg q6w for 4 cycles (C9-C12)

Timeline

• Start date: 2023-12-18
• Primary completion: 2028-09-01
• Completion: 2028-09-01
• First posted: 2023-09-28
• Last updated: 2024-02-05

Locations

2 sites across 1 country: France