I am glad you asked clarification for this. I should have made it clearer. In simple terms, the immune system has a way to control its responses called immune checkpoints. But cancer cells can hijack these checkpoints to evade the immune system in a tricky way and avoid being destroyed.

If we use a metaphor, cancer cells can take advantage of these checkpoints as tricky agents showing as a good guy with a mask. For example, they can use some unique molecules to send signals to immune cells, telling them to calm down and become less active.

These tricky cancer cells want to avoid being attacked and destroyed by the immune system.

My understanding is that it is a smart way for cancer cells to trick the immune system to survive and proliferate.

I hope this oversimplification makes sense to you.