Primary and secondary immune checkpoint inhibitors resistance in colorectal cancer: Key mechanisms and ways to overcome resistance

Engineered T cells for Colorectal Cancer

Colorectal cancer (CRC) is a major contributor to global cancer incidence and mortality. Conventional treatments have limitations; hence, innovative approaches are imperative. Recent advancements in cancer research have led to the development of personalized targeted therapies and immunotherapies. Immunotherapy, in particular, T cell-based therapies, exhibited to be promising in enhancing cancer treatment outcomes. This review focuses on the landscape of engineered T cells as a potential option for the treatment of CRC. It highlights the approaches, challenges and current advancements in this field. As the understanding of molecular mechanisms increases, engineered T cells hold great potential in revolutionizing cancer treatment. To fully explore their safety efficacy in improving patient outcomes, further research and clinical trials are necessary.

Targeting myeloid-derived suppressor cells promotes antiparasitic T-cell immunity and enhances the efficacy of PD-1 blockade (15 words)

Immune exhaustion corresponds to a loss of effector function of T cells that associates with cancer or chronic infection. Here, our objective was to decipher the mechanisms involved in the immune suppression of myeloid-derived suppressor cells (MDSCs) and to explore the potential to target these cells for immunotherapy to enhance checkpoint blockade efficacy in a chronic parasite infection. We demonstrated that programmed cell-death-1 (PD-1) expression was significantly upregulated and associated with T-cell dysfunction in advanced alveolar echinococcosis (AE) patients and in Echinococcus multilocularis-infected mice. PD-1 blockade ex vivo failed to reverse AE patients' peripheral blood T-cell dysfunction. PD-1/PD-L1 blockade or PD-1 deficiency had no significant effects on metacestode in mouse model. This was due to the inhibitory capacities of immunosuppressive granulocytic MDSCs (G-MDSCs), especially in the liver surrounding the parasite pseudotumor. MDSCs suppressed T-cell function in vitro in an indoleamine 2, 3 dioxygenase 1 (IDO1)-dependent manner. Although depleting MDSCs alone restored T-cell effector functions and led to some limitation of disease progression in E. multilocularis-infected mice, combination with PD-1 blockade was better to induce antiparasitic efficacy. Our findings provide preclinical evidence in support of targeting MDSC or combining such an approach with checkpoint blockade in patients with advanced AE. (200 words).

Microsatellite Instability: A Review of Molecular Epidemiology and Implications for Immune Checkpoint Inhibitor Therapy

Microsatellite instability (MSI) is one of the most important molecular characteristics of a tumor, which occurs among various tumor types. In this review article, we examine the molecular characteristics of MSI tumors, both sporadic and Lynch-associated. We also overview the risks of developing hereditary forms of cancer and potential mechanisms of tumor development in patients with Lynch syndrome. Additionally, we summarize the results of major clinical studies on the efficacy of immune checkpoint inhibitors for MSI tumors and discuss the predictive role of MSI in the context of chemotherapy and checkpoint inhibitors. Finally, we briefly discuss some of the underlying mechanisms causing therapy resistance in patients treated with immune checkpoint inhibitors.

Dostarlimab an Inhibitor of PD-1/PD-L1: A New Paradigm for the Treatment of Cancer

Immunomodulation checkpoints usually adopted by healthy cells by tumors might cause an imbalance between host surveillance and tumor progression. Several tumors are incredibly resistant to standard treatment. The dynamic and long-lasting tumor regressions caused by antibodies targeting the PD-1/PD-L1 checkpoint have suggested a rebalancing of the host-tumor relationship. Checkpoint antibody inhibitors, like anti-PD-1/PD-L1, are unique inhibitors that reduce tumor growth by modulating the interaction between immune cells and tumor cells. These checkpoint inhibitors are swiftly emerging as a highly promising strategy for treating cancer because they produce impressive antitumor responses while having a limited number of adverse effects. Over the past several years, numerous checkpoint antibody inhibitors pointing to PD-1, PDL-1, and CTLA-4 have been available on the market. Despite its enormous success and usefulness, the anti-PD treatment response is restricted to certain kinds of cancer. This restriction can be attributed to the inadequate and diverse PD-1 expression in the tumor (MET) micro-environment. Dostarlimab (TSR-042), a drug that interferes with the PD-1/PD-L1 pathway, eliminates a crucial inhibitory response of an immune system and, as a result, has the potential to cause severe or deadly immune-mediated adverse effects. As cancer immunotherapy, dostarlimab enhances the antitumor immune response of the body.