I am not a scientist or a MD but I always thought there was a strange logic in using immunotherapy against cancer. Virtually all chemotherapies cause depressio

I am not a scientist or a MD but I always thought there was a strange logic in using immunotherapy against cancer. Virtually all chemotherapies cause depression of the immune system, and it makes sense for patients who have an advanced form of cancer, as metastasis has a lot in common with wound healing [0]. Even NSAIDs are known to slow metastasis. So in my lay person view I have problems to understand how increasing the activity of the immune system would help. After all we are not the sum of isolated unspecialized cells, on contrary the ECM is a biology active area with lot of signaling. Maybe someone can shed some light on this question? [0] The biology of cancer, Weinberg