[Analysis of the efficacy and safety of preoperative programmed death protein-1 inhibitor combined with chemotherapy in immunotherapy-sensitive patients with locally advanced gastric cancer or adenocarcinoma of the esophagogastric junction].

Objective: To evaluate the short-term efficacy and safety of a preoperative combination of programmed cell death protein-1 (PD-1) inhibitor with either oxaliplatin + capecitabine (CapeOx) or oxaliplatin + tegafur gimeracil oteracil potassium (SOX) in the treatment of locally advanced immunotherapy-sensitive gastric cancer (LAGC) or adenocarcinoma of the esophagogastric junction (AEG). Methods: The cohort of this retrospective descriptive case series comprised patients with LAGC or AEG whose cancers had been determined to be immunotherapy- sensitive by endoscopic biopsy before treatment in the Gastrointestinal Cancer Center, Unit III, Peking University Cancer Hospital and Institute from 1 August 1 2021 to 31 January 2024. Patients with any one of the following three characteristics were immunotherapy-sensitive: (i) PD-L1 combined positive score (CPS) ≥5; (ii) microsatellite instability-high (MSI-H) / mismatch repair deficiency (dMMR); or (iii) Epstein-Barr virus-encoded RNA (EBER) positivity. All study patients received PD-1 inhibitors combined with CapeOx or SOX as a neoadjuvant or conversion treatment strategy before surgery. Patients with immune system diseases, distant metastases, or human epidermal growth factor receptor 2 positivity were excluded. Factors analyzed included pathological complete response, clinical complete response, major pathological response, R0 resection rate, surgical conversion rate, and safety of the treatment, including immune-related adverse events (irAEs) and surgical complications. Results: The study cohort comprised 39 patients (28 men and 11 women) of median age 62 (range 44-79) years. After the above-described preoperative treatment, radical resection of the 14 tumors that were initially considered unresectable was achieved (surgical conversion rate: 14/14). Twenty-three of the remaining 25 patients underwent radical resection. The last two patients achieved clinical complete responses and opted for a "non-surgical strategy" (watch and wait). Overall, 37 patients (94.9%) underwent radical resection, with an R0 resection rate of 100% (37/37), pathological complete response rate of 48.6% (18/37), and major pathological response rate of 62.2% (23/37). Of the 24 patients with CPS ≥ 5 (non-MSI-H/dMMR and non-EBER positive), 11 achieved pathological complete responses and one with CPS=95 achieved a clinical complete response. Of the eight patients with MSI-H/dMMR, six achieved pathological complete responses and one a clinical complete response. Of the seven patients with EBER positivity, one achieved a pathological complete response. After excluding patients with major pathological complete responses, there was a statistically significant difference in CPS scores between preoperative biopsy specimens and postoperative surgical specimens in 13 patients (7.769±5.570 vs. 15.538±16.870, t=2.287, P=0.041). All patients tolerated preoperative immunotherapy well; nine patients (9/39, 23.1%) had Grade I-II irAEs. There were no Grade III-IV irAEs. The five patients with pyloric obstruction before treatment tolerated normal diets after treatment. The incidence of postoperative complications among all patients who underwent surgery was 18.9% (7/37), including one case of Grade IIIA anastomotic leakage, one of Grade IIIA intestinal obstruction, one of Grade II abdominal hemorrhage, two of Grade II abdominal infection, one of Grade I intestinal obstruction. Additionally, one patient developed COVID-19 postoperatively. All patients recovered with symptomatic treatment. Conclusion: We found that preoperative treatment of patients with LAGC or AEG of one of three types (CPS≥5, dMMR+MSI-H, and EBER positivity) with a PD-1 inhibitor combined with CapeOx or SOX chemotherapy achieved promising effectiveness and safety, with high surgical conversion, R0 resection, and complete response rates.

[Regarding the selection of individualized therapy after neoadjuvant therapy for gastrointestinal tumors].

Gastrointestinal tumors have been widely concerned because of increasing morbidity and mortality. In the process of exploring the therapeutic patterns of gastrointestinal tumors, patients treated with neoadjuvant therapies have good effect of tumor regression and favorable prognosis. Thus, neoadjuvant therapy strategies are recommended by major guidelines of gastrointestinal tumors in the world. Meanwhile, they have a great impact on the traditional methods of surgery, the influence mainly involves the reduction of the surgical margin and the scope of lymph node dissection in gastric cancer, while involves performing organ preservation and watch & wait in selective patients with colorectal cancer. These effects and changes were based on effective control of local recurrence by neoadjuvant therapies, and the advantages of neoadjuvant therapy in terms of tumor regression and survival supported by many studies. It is also based on the patient's desire for organ preservation and non-surgical treatment. Meanwhile, application of neoadjuvant therapy strategies increase surgical difficulty and postoperative complications, but the overall impact on patient prognosis is weak. Therefore, the selection of an appropriate treatment model after neoadjuvant therapy requires an effective overall post-treatment evaluation. In particular, it is necessary to pay attention to the evaluation of imaging, endoscopy, etc., while effectively performing monitoring and follow-up, and finally establishing an appropriate salvage treatment. This article will review the status and problems of individualized treatment after neoadjuvant therapy of gastrointestinal tumor.