Safety and efficacy of immunotherapy plus chemotherapy as neoadjuvant treatment for patients with locally advanced gastric cancer: a retrospective cohort study

Background: The combined use of programmed death receptor-1 (PD-1) inhibitors and chemotherapy has reshaped the treatment landscape of advanced or metastatic gastric cancer (GC). This study aimed to assess the efficacy and safety of PD-1 inhibitors combined with chemotherapy in a neoadjuvant setting for locally advanced GC (LAGC). Methods: Patients diagnosed with clinical stage II-III GC undergoing neoadjuvant PD-1 inhibitors plus chemotherapy were enrolled from December 2019 to July 2022. Clinicopathological characteristics, pathological information, and survival data were recorded and analyzed. Results: A total of 42 eligible patients were enrolled, of whom 37 (88.1%) had clinical stage III disease. All the patients underwent surgery, and the R0 resection rate was 90.5%. Major pathological response (MPR) and pathological complete response (pCR) rates were 42.9% and 26.2%, respectively. The overall TNM downstaging rate was 76.2%. A total of 36 (85.7%) patients received adjuvant chemotherapy. With a median follow-up of 23.1 months, four patients died after tumor recurrence, and three were alive with recurrence. The 1-year overall survival (OS) and disease-free survival (DFS) rates were 94.4% and 89.5%, respectively, and the median OS and DFS were not reached. Neoadjuvant treatment was well tolerated with no grade 4-5 treatment-related adverse events (TRAEs) observed. The most common grade 3 TRAEs were anemia and alanine aminotransferase increase (n = 2 each, 9.6%). Conclusions: PD-1 inhibitors plus chemotherapy demonstrated promising efficacy, with encouraging pCR and survival outcomes in a neoadjuvant setting for patients with LAGC. The combined therapy also showed a good safety profile.