PMID: 23722425 , Related PDB id: 4KJY

Authors:

Weiskopf K, Ring AM, Ho CC, Volkmer JP, Levin AM, Volkmer AK, Ozkan E, Fernhoff NB, van de Rijn M, Weissman IL, Garcia KC

Title:

Engineered SIRPalpha variants as immunotherapeutic adjuvants to anticancer antibodies.

Journal:

Science. 2013 Jul 5;341(6141):88-91. doi: 10.1126/science.1238856. Epub 2013 May , 30.

Abstract:

CD47 is an antiphagocytic signal that cancer cells employ to inhibit macrophage-mediated destruction. Here, we modified the binding domain of human SIRPalpha, the receptor for CD47, for use as a CD47 antagonist. We engineered high-affinity SIRPalpha variants with about a 50,000-fold increased affinity for human CD47 relative to wild-type SIRPalpha. As high-affinity SIRPalpha monomers, they potently antagonized CD47 on cancer cells but did not induce macrophage phagocytosis on their own. Instead, they exhibited remarkable synergy with all tumor-specific monoclonal antibodies tested by increasing phagocytosis in vitro and enhancing antitumor responses in vivo. This "one-two punch" directs immune responses against tumor cells while lowering the threshold for macrophage activation, thereby providing a universal method for augmenting the efficacy of therapeutic anticancer antibodies.