Evaluation of the ability of immune humanized mice to demonstrate CD20-specific cytotoxicity induced by ofatumumab.

CD20 monoclonal antibodies are well-established therapeutics for the treatment of B-cell malignancies. Several mechanisms of target cell killing occur from anti-CD20 therapy including complement-dependent cell lysis (CDC) and antibody-dependent cell-mediated cytotoxicity (ADCC). Human Fc Receptors (FcR) are required to mediate these functions and are either not present or not cross-reactive in mice and most animal species. In contrast, some non-human primates have cross-reactive FcR however, their cellular expression and function may differ from humans. Therefore, we tested bone marrow-liver-thymus (BLT) humanized mice to determine if they could recapitulate the pharmacokinetics, pharmacodynamics and potential toxicities of Ofatumumab, for which CDC is the predominant mechanism of action. Ofatumumab-treated BLT mice depleted B cells in a dose-dependent manner in all tissues sampled and recapitulated the pharmacokinetics observed in humans, suggesting that BLT mice can mediate the CDC effector mechanism associated with biological drug products. This article is protected by copyright. All rights reserved.