How does yervoy enhance the body's anti tumor defenses?

Yervoy is ipilimumab, a monoclonal antibody that blocks CTLA-4, a checkpoint on T cells that normally acts as a brake on immune activation.

What CTLA-4 does
- When T cells are activated (for example, in the lymph nodes), CTLA-4 dampens their activation by outcompeting the stimulatory receptor CD28 for B7 ligands on antigen-presenting cells.
- This helps prevent overactivation of the immune system, but it can also limit the body’s ability to attack tumors.

How Yervoy enhances anti-tumor defenses
- By blocking CTLA-4, ipilimumab releases the brake, allowing T cells to become more strongly activated and expand more in response to tumor antigens.
- This increases the number and activity of tumor-directed T cells (especially CD8+ cytotoxic T cells) that can recognize and kill cancer cells.
- It may also reduce suppression by regulatory T cells (Tregs) within the tumor microenvironment, and in some cases can deplete intratumoral Tregs via antibody-related mechanisms.
- In some settings, it’s used in combination with other checkpoint inhibitors (e.g., PD-1/PD-L1 inhibitors) to boost responses, though this can raise the risk of immune-related side effects.

In short: Yervoy enhances the body's anti-tumor defenses by lifting the CTLA-4–mediated brake on T cells, promoting a stronger, more durable T-cell–mediated attack on cancer cells.