SIRPA and cancer: SIRPα-expressing myeloid cells bind to CD47-expressing tumour cells and mediate negative regulation of cytotoxicity of macrophage, neutrophil and microglia cells towards cancer.88 Blockade of the SIRPα-CD47 axis will increase phagocytosis of macrophages.89 Hu5F9-G4 (magrolimab), a humanized antibody against CD47, has been used in preclinical research among HER2-positive breast cancer patients combined with trastuzumab.90