The NEOSUMMIT-03 phase 2 clinical trial has demonstrated promising results for patients with locally advanced gastroesophageal junction adenocarcinoma (GEJA), showing significant therapeutic benefits from perioperative tislelizumab combined with chemotherapy.
Significant Clinical Outcomes
The study, conducted in China, enrolled 32 patients with locally advanced GEJA between October 2022 and June 2023. The treatment regimen achieved its primary endpoint with a 50% major pathological response (MPR) rate, substantially exceeding the planned target of 33%. Additionally, 28.1% of patients achieved pathological complete response in primary tumors, while 25% reached ypT0N0 status.
The median follow-up period of 21.9 months revealed encouraging survival metrics, with 18-month overall survival (OS) rate of 84.4% and event-free survival (EFS) rate of 74.4%. Among the study participants, 68.8% remained alive and free of recurrence at the data cutoff date.
Treatment Protocol and Safety Profile
Patients received tislelizumab (200mg) intravenously every three weeks, combined with oxaliplatin and S-1 chemotherapy. The treatment demonstrated manageable toxicity, with 31.2% of patients experiencing grade 3 or 4 treatment-related adverse events. Thrombocytopenia was the most common serious side effect, occurring in 9.4% of patients.
Biomarker Analysis and Patient Responses
A notable finding emerged regarding tumor characteristics and treatment response. Patients with intestinal-type GEJA showed significantly higher response rates, with 75% achieving MPR compared to 33.3% in diffuse-type and 36.4% in mixed-type tumors. This suggests that Lauren histological classification might be a valuable predictor of treatment outcomes.
Surgical Outcomes
The surgical phase of the treatment showed positive results, with 96.9% of patients achieving R0 resection. Total gastrectomy was performed in 84.4% of cases, with a manageable perioperative morbidity rate of 15.6% and no 30-day mortality reported.
Future Implications
While these results are promising, the researchers acknowledge the study's limitations as a single-arm phase 2 trial with a relatively small sample size. A larger randomized controlled trial has been initiated to validate these findings (ChiCTR2400081098).
The study represents a significant step forward in the treatment of locally advanced GEJA, particularly given the rising incidence of this cancer type and the current lack of standardized treatment protocols. These findings could potentially influence future treatment strategies for GEJA patients, especially in determining optimal patient selection based on tumor characteristics.
