Discovery of an antibody that stimulates the immune system to eliminate cancer cells

André Veillette

Credit: Institut de recherches cliniques de Montréal

Major work led by Dr. André Veillette’s team at the Institut de recherches cliniques de Montréal (IRCM), in collaboration with a group of researchers, and just published in Nature Immunology, managed to identify a previously unknown way which prevents phagocytosis, which is a process that promotes the immune system’s response to cancer.

Macrophages are cells of the immune system. One of the roles of macrophages is to engulf, or ‘eat’, cells that are defective or dangerous, including cancer cells. This process is named phagocytosis. Macrophages can be called into action to eliminate cancer cells. However, this capacity is often defective, because macrophages are put in a state of dormancy by the cancer cells. This is in part because a particular molecule called CD47 is often over-abundant on cancer cells. CD47 prevents phagocytosis by triggering a molecule or “receptor”on macrophages named SIRPα.  Agents that block the ability of CD47 to trigger SIRPα have shown promising results for treating cancer.

The research team collaborated in the identification of a previously unknown way by which CD47 prevents phagocytosis. They found that CD47 also blocks the molecule SLAMF7 on blood cancer cells, such as multiple myeloma and lymphoma. The researchers developed a new antibody, named Z10, that frees SLAMF7 from CD47, thereby augmenting elimination of tumor cells. When combined with other agents Z10 is highly effective against cancer cells expressing SLAMF7, at least in mice.