June 2026: Cohen: When cleanup goes wrong: Immune cells turned against the body

A new study, led by Dr. Merav Cohen, Edmond J. Safra affiliate, and her MD-PhD students Roi Balaban and Ori Moskowitz (Medical & Health Sciences), has revealed an unexpected twist in the behavior of the immune system within tumors: the very process meant to clear cellular debris may actually fuel cancer progression.

The researchers have developed an innovative technique called Effero-seq, allowing scientists to closely monitor how macrophages, key immune cells, change after consuming dead cells. Their findings uncover a previously hidden mechanism by which tumors may exploit the body's own defenses.

Using this method, the team discovered that when macrophages engulf dead cancer cells, they undergo a profound transformation. Instead of supporting anti-tumor activity, these cells adopt features that actively encourage tumor survival and expansion.

The altered macrophages were shown to stimulate the growth of new blood vessels that feed tumors, while simultaneously becoming less responsive to signals that would normally trigger anti-cancer immune reactions. This shift in behavior was also linked to worse outcomes among melanoma patients.

Notably, the researchers found that these changes are not short-lived. Once reprogrammed, macrophages appear to retain their tumor-supporting state over time, suggesting that the process has lasting consequences on the immune landscape within cancer tissues.

This study, published in Science Immunology,  sheds light on how tumors can reshape immune responses to their advantage and points to new possibilities for therapy. By targeting macrophage reprogramming or the process of clearing dead cells, known as efferocytosis, future treatments may be able to disrupt this harmful cycle.