A prospective phase II clinical trial of total neoadjuvant therapy for locally advanced gastric cancer and gastroesophageal junction adenocarcinoma.

To investigate the safety and efficacy of the neoadjuvant chemoradiotherapy (NCRT) followed by neoadjuvant consolidation chemotherapy (NCCT) and surgery for locally advanced gastric cancer (GC) or gastroesophageal junction (GEJ) adenocarcinoma. Patients diagnosed as locally advanced GC or Siewert II/III GEJ adenocarcinoma with clinical stage T3-4 and/or N positive were prospectively enrolled. Patients underwent NCRT (45 Gy/25 fractions) with concurrent S-1, followed by NCCT (4 to 6 cycles of the SOX regimen) 2 to 4 weeks after NCRT. Gastric cancer radical resection with D2 lymph node dissection was performed 4 to 6 weeks after the total neoadjuvant therapy. The study was conducted from November 2019 to January 2023, enrolling a total of 46 patients. During the NCRT, all patients completed the treatment without dose reduction or delay. During the NCCT, 32 patients (69.6%) completed at least 4 cycles of chemotherapy. Grade 3 or higher adverse events in NCRT (5 cases) were non-hematological. During the course of NCCT, a notable occurrence of hematological toxicities was observed, with grade 3 or higher leukopenia (9.7%) and thrombocytopenia (12.2%) being experienced. A total of 28 patients (60.9%) underwent surgery, achieving R0 resection in all cases. A significant proportion of cases (71.4%) exhibited pathological downstaging to ypT0-2, while 10 patients (35.7%) demonstrated a pathologic complete response (pCR). The total neoadjuvant therapy comprising NCRT followed by NCCT and surgery demonstrates a low severe adverse reactions and promising efficacy, which could be considered as a viable treatment for locally advanced GC or GEJ adenocarcinoma.Trial registration: Clinicaltrials.gov (registration number: NCT04062058); the full date of first trial registration was 20/08/2019.