Immune Checkpoint Molecules and Host Directed Therapy for Cancer Treatment

Cancer growth is influenced not only by intrinsic genetic abnormalities within the tumour but also by dynamic interactions with the host immune system and the tumour microenvironment (TME). Immune checkpoint molecules, such as CTLA-4, PD-1, LAG-3, TIM-3, and TIGIT, are very important for controlling immune activity and keeping the body from attacking itself. However, cancer cells use these pathways to avoid being attacked by the immune system. Immune checkpoint blockade (ICB) has transformed cancer treatment by reinstating anti-tumour immunity; nevertheless, sustained therapeutic benefit is realized in only a fraction of patients due to inherent and acquired resistance, immune cell malfunction, and a markedly immunosuppressive TME. Host-directed therapies (HDTs) have arisen as an adjunctive approach focused on re-establishing immunological competency rather than directly attacking tumour cells. HDTs fix some of the biggest problems with ICB, such as poor immunological priming, metabolic insufficiency, suppressive myeloid and regulatory cell populations, and limited immune infiltration. They do this by changing host immune pathways, cellular metabolism, cytokine networks, and stromal components. Combining ICB with HDTs is a smart, mechanism-based way to improve treatment that combines checkpoint release with immune support and changes in the microenvironment. This method improves immune fitness, increases the body’s ability to fight cancer, limits adaptive resistance, and encourages long-lasting tumour control. It may also make it less necessary to boost immune activation. These ideas put combination treatments that include immune checkpoint blockade and host-directed therapy in a good place to move forward with next-generation cancer immunotherapy.