Immunotherapy strengthens or manipulates the immune system to attack cancer cells or pathogens more effectively. Its primary mechanisms include:

1. Immune Checkpoint Inhibitors:
   Block proteins that prevent the immune system from attacking cancer cells.

2. Cancer Vaccines:
   Train the immune system to recognize and combat specific cancer-related antigens.

3. Monoclonal Antibodies:
   Synthetic proteins designed to bind to and destroy cancer cells.

4. Adoptive Cell Therapy:
   Uses genetically engineered immune cells, such as T-cells, to target tumors.

5. Cytokine Therapy:
   Enhances the activity of immune cells by using proteins like interleukins and interferons.