Balancing Tumor Immunotherapy and Immune-Related Adverse Events: Unveiling the Key Regulators

Tumor immunotherapy has emerged as a promising approach in cancer treatment in recent years, offering vast potential. This method primarily involves targeting and inhibiting the suppressive checkpoints present in different immune cells to enhance their activation, ultimately leading to tumor regression. However, tumor cells exploit the surrounding immune cells and tissues to establish a tumor microenvironment (TME) that supports their survival and growth. Within the TME, the efficacy of effector immune cells is compromised, as tumor cells exploit inhibitory immune cells to suppress their function. Furthermore, certain immune cells can be co-opted by tumor cells to facilitate tumor growth. While significantly enhancing the body's tumor immunity can lead to tumor regression, it can also result in severe toxic side effects and an inflammatory factor storm. As a consequence, patients often discontinue treatment due to immune-related adverse events (irAEs) or, in extreme cases, succumb to toxic side effects before experiencing tumor regression. In this analysis, we examined several remission regimens for irAEs, each with its own drawbacks, including toxic side effects or suppression of tumor immunotherapy, which is undesirable. A recent research study, specifically aimed at downregulating intestinal epithelial barrier permeability, has shown promising results in reducing the severity of inflammatory bowel disease (IBD) while preserving immune function. This approach effectively reduces the severity of IBD without compromising the levels of TNF-α and IFN-γ, which are crucial for maintaining the efficacy of tumor immunotherapy. Based on the substantial similarities between IBD and ICI colitis (combo immune checkpoint inhibitors-induced colitis), this review proposes that targeting epithelial cells represents a crucial research direction for mitigating irAEs in the future.