The complex interactions between the innate and adaptive immune systems function to recognize and clear pathogens or transformed cells, but inefficient interactions between these two systems can result in harmful immunologic responses including chronic infections and the development of cancer. Several hallmarks of dysfunctional adaptive immune responses often detected in tumors share specific features with ineffective immunity in chronic infections. The members of the micromilieu actively participate in the process of tumorigenesis or chronification of infection by modulating innate and adaptive immune system interactions leading e.g. to insufficient T cell responses. The best example is given by the acquisition of an “exhausted” state of cytotoxic CD8+ T cells (CTLs) responding to chronic infections or tumors that are associated with elevated expression of inhibitory receptors and impaired cytokine response. Targeting these major inhibitory pathways by immune checkpoint blockers represents a prime example of successful clinical translation of tumor-specific immunotherapies. Understanding the mechanisms behind (mal)adaptations of the immune system is crucial for achieving therapeutic benefits.

The establishment and co-evolution of a dynamic microenvironment niche constituted by the recruitment of numerous cell types dampen immune responses and thus contribute to the development of neoplastic transformation as well as infection. Although there are examples of successful immunotherapeutic approaches (CAR-T cells, immune checkpoint inhibitors, or mRNA vaccination), a large percentage of patients with cancer or chronic infections still do not benefit from these therapies or develop severe immune-related adverse events. The reasons for these failures are not well understood. A possible explanation might be that current immunotherapies target predominantly the effector arm of the immune system by trying to reactivate dysfunctional T cells, but do not sufficiently address the influence of the innate immune system and the contributions of the tumor microenvironment (TME) niche. The main problem we would like to address in this special issue is how inappropriate function of the innate immune system affects adaptive immunity and contributes to inefficient anti-cancer immunity and chronification of infections.

The central goal is to provide a more precise understanding of the various (common and novel) immune evasion mechanisms in cancers and in chronic infections to obtain a detailed map of common and disease-specific immune escape checkpoints. To that aim, we want to compile a wide array of interdisciplinary studies exploring a comparative and multi-layered analysis of mechanisms responsible for inefficient immune responses, including novel approaches i.e. multi-omics or epigenetic signaling. We would also like to combine studies from different fields, including basic and clinical immunology, oncology, and virology/microbiology. We welcome the submission of Original Research, Review, Mini-Review, Methods, Case report, and Perspective articles that cover, but are not limited to the following topics:

• Convergent mechanisms supporting immune escape in preclinical models (tumors and chronic infections)

• Convergent evasion mechanisms mediated by tumor-infiltrating suppressive cells (Treg, MDSC, macro-phages, soluble mediators, signaling, metabolism, ...)

• Convergent immune evasion mechanisms mediated by chronic infection (viral or parasite)

• Novel strategies to modulate the TME by direct or indirect targeting of immune suppressor cells.

• Approaches to enhance persistence and resilience of anticancer T cells

• Combinatorial therapeutic strategies (mRNA, antibodies, immune checkpoint blockers …) that target convergent immune evasion mechanisms

Manuscripts consisting solely of bioinformatics or computational analysis of public genomic or transcriptomic databases which are not accompanied by robust and relevant validation (clinical cohort or biological validation in vitro or in vivo) are out of scope for this topic.