Mismatch Repair Deficient or MSI-High Solid Tumors

Brief Summary Lymph node metastasis (LNM) is a key factor influencing treatment decisions and prognosis in patients with gastric cancer. Lymphatic invasion (LI) is an important pathological predictor of LNM and a core component of the eCURA risk scoring system after endoscopic submucosal dissection (ESD) for early gastric cancer. However, whether LI has the same predictive value for LNM across different mismatch repair (MMR) statuses remains unclear. Compared with proficient mismatch repair (pMMR) gastric cancer, deficient mismatch repair (dMMR) gastric cancer has distinct molecular pathological features and an immune-enriched tumor microenvironment. In early gastric cancer, if LI is associated with a lower LNM risk in dMMR tumors than in pMMR tumors, existing LI-based eCURA risk assessment may overestimate LNM risk in patients with dMMR early gastric cancer and consequently affect decisions regarding additional surgery after ESD. Therefore, this study aims to systematically evaluate the impact of MMR status on the association between LI and LNM using upfront-surgery and post-ESD additional-surgery cohorts from our center, and to explore the potential clinical value of MMR status in refining eCURA-based risk stratification for early gastric cancer.

The goal of this clinical trial is to determine the most effective dose of EIK1005 that a person can take safely. Additionally, this study will test how well EIK1005 is tolerated alone and in combination with pembrolizumab in treating patients with advanced cancer.

This is a randomized, non-comparative, open-label, two-arm phase II clinical trial designed to evaluate the efficacy and safety of neoadjuvant therapy with adebrelimab plus induction chemotherapy versus adebrelimab plus SHR-8086 in patients with dMMR/MSI-H gastric or gastroesophageal junction adenocarcinoma.

dMMR/MSI-H is a key molecular subtype of gastric cancer, found in 8-22% of cases. It is typically associated with older age, female sex, distal tumor location, and intestinal histology (Lauren classification). While this subtype predicts better survival in locally advanced disease, its prognostic role in metastatic settings is less clear. Notably, dMMR/MSI-H tumors are often resistant to conventional chemotherapy. Conversely, they demonstrate exceptional sensitivity to immunotherapy. This has led to effective strategies using immune checkpoint inhibitors, either alone or combined with chemotherapy, in both neoadjuvant and advanced disease settings. However, key challenges remain. Prospective data are largely from Western populations, leaving the efficacy in Asian patients-who bear a high disease burden-less defined. Furthermore, about half of dMMR/MSI-H patients exhibit primary or acquired resistance to immunotherapy. A deeper understanding of the tumor-immune dynamics during treatment is crucial to uncover resistance mechanisms and improve patient outcomes.