ERBB2 and B-cell chronic lymphocytic leukemia: FHR4 multimeric immunoconjugates targeting CD20 – by replacing the anti‐HER2 targeting system – may therefore have a higher cytolytic potential in lymphoma cells than in solid tumour cells, whereas it has been shown that abrogation of the FH function in combination with ofatumumab or rituximab resulted in an increased susceptibility of primary CLL cells to CDC (Horl et al., 2013).