Abstract 427P
Background
Conversion therapy is an option for unresectable locally advanced gastric cancer. The aim of this study is to evaluate the safety and efficacy ofconversion therapy for patients with initially unresectable gastric cancer treated with chemoradiotherapy combined with tislelizumab.
Methods
For initially unresectable locally advanced gastric cancer gastroesophageal junction cancer, all patients received three cycles of conversion therapy included one cycle (3 weeks) of induction chemotherapy of S-1 and nab-PTXin combination with tislelizumab, followed by one cycle of chemoradiotherapy (45Gy/1.8Gy with concurrent nab-PTX) and two cycles of tislelizumab, and one cycle of consolidation chemotherapy of S-1 and nab-PTX combined with tislelizumab. After 3 cycles of treatment, the patients were evaluated by MDT team for surgery feasibility. If the surgery performed, the patients would receive postoperative chemotherapy (S-1 and nab-PTX，the dose of nab-PTX adjusted to: 100mg/m2, ivgtt, d1,8, q3w) combined with tislelizumab. Otherwise, it was considered the conversion treatment failed, the patients would receive chemotherapy combined with immunotherapy until the disease progression. Primary endpoint was R0 resectionrate. Secondary endpoints included PFS, OS, ORR, DCR, and safety.
Results
From Sep 2022 to Dec 2023, 17 patients were enrolled in the trial, including 10 males, 7 females, 5 in stage III, and 12 in stage IV. Among them, 4patients have not been evaluated yet, 5 patients were resectable, but 1 patient achieved a complete clinical response and refused surgery. The R0 resection rate was 30.8% (4/13), the ORR was 84.6% (11/13). For the safety, 2 patients developed G2-G3 immune pneumonia,1 patient developed G4 immune pneumonia, 1 patient developed G2 immune dermatitis, and 1 case developed 3rd degree leukopenia andneutropenia. 2 patients died due to brain metastasis and immune pneumonia respectively.
Conclusions
Interim results showed that for initially unresectable locally advanced gastric cancer, the combination of concurrent chemoradiotherapy and tislelizumab showed promising outcomes and well tolerated.
Clinical trial identification
NCT05528367.
Legal entity responsible for the study
The authors.
Funding
BeiGene.
Disclosure
All authors have declared no conflicts of interest.