With companies lining up to block CD47 for cancer, the cell surface protein is emerging as one of the top new targets in oncology. But the list of suitors could be about to get a lot longer as the target could have uses in a much broader range of indications, according to two studies from Stanford University that extend its prospects to cardiovascular disease and transplant biology, and hint at roles in several more diseases.
The discoveries have been licensed by Forty Seven Inc. as part of the 100-plus patent portfolio licensed from the university when the company was spun out by Stanford professor Irving Weissman to develop inhibitors of CD47 for cancer. The company raised $75 million in series A financing in February, and has its lead compound, the CD47-blocking mAb Hu5F9-G4, in Phase I for acute myelogenous leukemia (AML) and solid tumors.
Weissman, a professor of pathology and developmental biology, is also director of the Institute of Stem Cell Biology and Regenerative Medicine at Stanford.
Last week's announcement by Tioma Therapeutics Inc. of an $86 million series A round brings to six the number of companies with disclosed programs targeting CD47 (see Table: Chasing CD47). Since April of last year, companies targeting CD47 have raised more than $247 million.
Commonly known as a "don't eat me" signal, CD47 is expressed on the surface of red blood cells (RBCs), and many other cell types, where it interacts with the receptor protein SIRPA on macrophages to prevent phagocytosis.
Cancers can co-opt this biology, up-regulating CD47 to avoid getting eaten by macrophages. Blocking CD47 via mAbs or SIRPA-derived antagonists allows macrophages to both clean up