Beside monoclonal antibodies a recombinant FH derived protein composed of CCPs 18-20 (hSCR18-20) was successfully used to inhibit the binding of FH to chronic lymphocytic leukemia cells and an FHR-4—anti-HER2 immunoconjugate was able to induce complement dependent cytotoxicity on HER2 expressing tumor cells that are known to be resistant to complement mediated lysis (159–161). Here, FH is linked to B-cell chronic lymphocytic leukemia.