Enhanced Photodynamic Therapy Synergizing with Inhibition of Tumor Neutrophil Ferroptosis Boosts Anti-PD-1 Therapy of Gastric Cancer

For tumor treatment, the ultimate goal in tumor therapy is to eliminate the primary tumor, manage potential metastases, and trigger an antitumor immune response, resulting in the complete clearance of all malignant cells. Tumor microenvironment (TME) refers to the local biological environment of solid tumors and has increasingly become an attractive target for cancer therapy. Neutrophils within TME of gastric cancer (GC) spontaneously undergo ferroptosis, and this process releases oxidized lipids that limit T cell activity. Enhanced photodynamic therapy (PDT) mediated by di-iodinated IR780 (Icy7) significantly increases the production of reactive oxygen species (ROS). Meanwhile, neutrophil ferroptosis can be triggered by increased ROS generation in the TME. In this study, a liposome encapsulating both ferroptosis inhibitor Liproxstatin-1 and modified photosensitizer Icy7, denoted LLI, significantly inhibits tumor growth of GC. LLI internalizes into MFC cells to generate ROS causing immunogenic cell death (ICD). Simultaneously, liposome-deliver Liproxstatin-1 effectively inhibits the ferroptosis of tumor neutrophils. LLI-based immunogenic PDT and neutrophil-targeting immunotherapy synergistically boost the anti-PD-1 treatment to elicit potent TME and systemic antitumor immune response with abscopal effects. In conclusion, LLI holds great potential for GC immunotherapy.

[Skip metastasis at the esophageal resection margin in radical gastrectomy: clinical characteristics of 30 cases]

Objective: To summarize the clinical characteristics of patients with skip metastasis at esophageal resection margin during radical gastrectomy. Methods: This is a descriptive study of case series. Relevant data from 2006 to 2022 were collected from two major gastric cancer consultation and treatment centers: Nanjing Drum Tower Hospital and Jinling Hospital.Characteristics, surgical approach, number of dissected lymph nodes, immunohistochemical staining, and pathological staging were summarized and analyzed. The distribution of residual tumor cells at the esophageal margins was further analyzed at the cellular and tissue levels. Skip metastasis at the esophageal resection margin was defined as a negative esophageal margin with a positive margin in the cephalad donut. Results: Thirty (0.33%, 30/8972) eligible patients, 24 (80.0%) of whom were male, were identified in the two centers. The mean age was 63.9±11.0 years. Seventeen (56.7%) of these patients had papillary or tubular adenocarcinomas, including 13 (43.3%) poorly- and four (13.3%) moderately-differentiated tumors; four (13.3%) had signet-ring cell carcinomas; four (13.3%) mucinous adenocarcinomas; three (10.0%) mixed adenocarcinomas, including two with poorly-differentiated tubular adenocarcinomas mixed with signet-ring cell carcinoma and mucinous adenocarcinoma; and one had a poorly differentiated tubular adenocarcinoma mixed with signet-ring cell carcinoma. Two patients (6.7%) had other types of cancer, namely adenosquamous carcinoma in one patient and undifferentiated carcinoma in the other one. The predominant tumor sites were the lesser curvature (n=26, 86.7%) and the cardia (n=24, 80.0%). The mean tumor diameter was 6.6 cm, mean distance between tumor and esophageal resection margin was 1.5 cm, and proportions of tumor invasion into the dentate line, nerves, and vessels were 80.0% (24/30), 86.7%(26/30), and 93.3% (28/30), respectively. The mean number of lymph nodes resected was 20.4±8.9. The pathological stage was mainly T4 (n=18, 60.0%) and N3 (n=21, 70.0%), the median Ki67 was 52.7%, and the rates of positivity for HER2, EGFR, VEGFR, E-cadherin and PD-L1 were 40.0% (12/30), 46.7% (14/30), 80.0% (24/30), 86.7% (26/30) and 16.7% (5/30), respectively. At the cellular level, cancer cells were mainly distributed in small focal areas, as cell masses, or as tumor thrombi; large numbers of widely distributed atypic cells were seldom observed. At the tissue level, cancer cells were located in the mucosal layer in seven patients (23.3%), in the submucosal layer in 18 (60.0%), and in the muscular layer in five (16.7%); no cancer cells were identified in the outer membrane. Five of the seven tumors were located in the lamina propria, two in the muscularis mucosae, and none in the mucosal epithelium. Conclusion: Patients with skip metastasis at the esophageal resection margin at radical gastrectomy have unfavorable tumor biology and a high proliferation index, are at a late pathological stage, and the residual cancer is mostly located in the submucosa.