Conversion Therapy Plus Surgery and Radiotherapy for Retroperitoneal Nodal Metastases in Gastric Cancer

Description

This is a randomized, controlled, multicenter phase II clinical trial evaluating the efficacy and safety of conversion therapy combined with radical gastrectomy and adjuvant radiotherapy targeting para-aortic (station 16) lymph nodes in patients with gastric adenocarcinoma and isolated station 16 nodal metastases. Eligible participants must have no evidence of peritoneal dissemination, visceral metastases, or non-regional lymphatic spread. Based on PD-L1 combined positive score (CPS), patients in the experimental arm will receive systemic therapy with SOX (S-1 plus oxaliplatin) with or without a PD-1 inhibitor, followed by D2 gastrectomy and postoperative adjuvant SOX chemotherapy, then intensity-modulated radiotherapy (IMRT) to the para-aortic region. The control arm will receive standard chemotherapy with CAPEOX or SOX, with or without immunotherapy, according to CPS status. The primary endpoint is progression-free survival (PFS), with secondary endpoints including overall survival (OS), objective response rate (ORR), disease control rate (DCR), and safety. This study aims to explore whether the addition of locoregional treatment to systemic therapy improves long-term outcomes in this select patient population.

Interventions

• SOX regimen (Drug)
  The SOX regimen consists of oxaliplatin 130 mg/m² IV on day 1 plus oral S-1 (tegafur/gimeracil/oteracil) 40-60 mg twice daily, taken on days 1-14 followed by 7 days off, in a 21-day cycle. Experimental arm: 3 cycles before surgery, 5 cycles after surgery. Control arm: up to 8 cycles as standard systemic therapy.
• CAPEOX regimen (Drug)
  The CAPEOX regimen consists of oxaliplatin 130 mg/m² IV on day 1 plus oral capecitabine 1000 mg/m² twice daily on days 1-14, repeated every 3 weeks (q3w), up to 8 cycles. Used as a standard chemotherapy option in the control arm, with or without PD-1 inhibitor according to PD-L1 CPS score.
• PD-1 inhibitor (Drug)
  A PD-1 inhibitor is administered intravenously at a fixed dose of 200 mg every 3 weeks. It is combined with SOX in the experimental arm (CPS ≥1 patients) during conversion and adjuvant phases, and with CAPEOX or SOX in the control arm (CPS ≥1 patients). Maintenance PD-1 inhibitor continues for up to 1 year or until disease progression or unacceptable toxicity.
• Para-aortic lymph node radiotherapy (IMRT to station 16) (Radiation)
  Intensity-modulated radiotherapy (IMRT) is delivered postoperatively to the para-aortic (station 16) nodal basin. Elective nodal basin: 45-50 Gy in 25 fractions Positive nodes: 56-60 Gy in 25 fractions Radiotherapy is given concurrently with oral capecitabine or S-1 as radiosensitizers.
• Capecitabine / S-1 (radiosensitizer during IMRT) (Drug)
  During para-aortic IMRT, patients receive concurrent oral capecitabine 825 mg/m² twice daily on radiation days, or oral S-1 dosed according to body surface area. These agents are used as radiosensitizers during postoperative radiotherapy.

Eligibility criteria

Conditions

Locations

• Shandong Cancer Hospital and Institute — Jinan, Shandong, China