Neoadjuvant/Perioperative Treatment Affects Spatial Distribution and Densities of Tumor Associated Neutrophils and CD8+ Lymphocytes in Gastric Cancer

Mapping spatial heterogeneity in gastric cancer microenvironment

Gastric cancer (GC) is difficult to characterize due to its heterogeneity, and the complicated heterogeneity leads to the difficulty of precisely targeted therapy. The spatially heterogeneous composition plays a crucial role in GC onset, progression, treatment efficacy, and drug resistance. In recent years, the technological advancements in spatial omics has shifted our understanding of the tumor microenvironment (TME) from cancer-centered model to a dynamic and variant whole. In this review, we concentrated on the spatial heterogeneity within the primary lesions and between the primary and metastatic lesions of GC through the TME heterogeneity including the tertiary lymphoid structures (TLSs), the uniquely spatial organization. Meanwhile, the immune phenotype based on spatial distribution was also outlined. Furthermore, we recapitulated the clinical treatment in mediating spatial heterogeneity in GC, hoping to provide a systematic view of how spatial information could be integrated into anti-cancer immunity.

The effect of neoadjuvant chemotherapy on the tumor immune microenvironment in gastrointestinal tumors

In recent years, numerous studies have demonstrated that the tumor immune microenvironment (TIME) is capable of regulating the growth of tumors, and tumor-infiltrating immune cells in the TIME can affect the prognosis and treatment responses of patients. Consequently, therapies targeting these immune cells have emerged as important antitumor treatments. As a crucial componet of the perioperative treatment of malignant tumors, neoadjuvant chemotherapy (NACT) can improve the surgical resection rate and prognosis of patients and is a suitable clinical model to evaluate the effect of chemotherapy on the TIME. To provide a rationale for developing valid combinational therapies, this review summarizes the impact of NACT on the TIME, the relationship between tumor-infiltrating immune cells and treatment responses of patients, and the prognostic value of these infiltrating immune cells.

Evaluation of histopathological response to neoadjuvant therapy in rectal cancer using slide-free, stain-free multimodal multiphoton microscopy

Neoadjuvant therapy has become a standard treatment for patients with locally advanced rectal cancer to achieve better prognostic outcomes. The response to treatment has been shown to correlate closely with the prognosis. However, current evaluation systems only provide coarse assessment on limited information, due to the lack of accurate and reproducible approach for quantitation of different types of responses. In this study, a novel stain-free, slide-free multimodal multiphoton microscopy imaging technique was applied to image rectal cancer tissues after neoadjuvant therapies with high resolution and contrast. Qualitative and quantitative evaluation of tumor, stromal, and inflammatory responses were demonstrated which are consistent with current tumor regression grading system using American Joint Committee on Cancer criteria, showing the great potential of such approach to build a more informative grading system for accurate and standardizable assessment of neoadjuvant therapy in rectal cancer.

Therapeutic strategies for gastric cancer targeting immune cells: Future directions

Gastric cancer (GC) is a malignancy with a high incidence and mortality, and the emergence of immunotherapy has brought survival benefits to GC patients. Compared with traditional therapy, immunotherapy has the advantages of durable response, long-term survival benefits, and lower toxicity. Therefore, targeted immune cells are the most promising therapeutic strategy in the field of oncology. In this review, we introduce the role and significance of each immune cell in the tumor microenvironment of GC and summarize the current landscape of immunotherapy in GC, which includes immune checkpoint inhibitors, adoptive cell therapy (ACT), dendritic cell (DC) vaccines, reduction of M2 tumor-associated macrophages (M2 TAMs), N2 tumor-associated neutrophils (N2 TANs), myeloid-derived suppressor cells (MDSCs), effector regulatory T cells (eT_regs), and regulatory B cells (B_regs) in the tumor microenvironment and reprogram TAMs and TANs into tumor killer cells. The most widely used immunotherapy strategies are the immune checkpoint inhibitor programmed cell death 1/programmed death-ligand 1 (PD-1/PD-L1) antibody, cytotoxic T lymphocyte–associated protein 4 (CTLA-4) antibody, and chimeric antigen receptor T (CAR-T) in ACT, and these therapeutic strategies have significant anti-tumor efficacy in solid tumors and hematological tumors. Targeting other immune cells provides a new direction for the immunotherapy of GC despite the relatively weak clinical data, which have been confirmed to restore or enhance anti-tumor immune function in preclinical studies and some treatment strategies have entered the clinical trial stage, and it is expected that more and more effective immune cell–based therapeutic methods will be developed and applied.