Preclinical B cell depletion and safety profile of a brain‐shuttled crystallizable fragment‐silenced CD20 antibody

Abstract

Background: The blood–brain barrier (BBB) presents a major challenge for the development of monoclonal antibody (mAb)-based therapies for brain disorders. To improve the likelihood of success of such therapies, Roche Brainshuttle technology utilizes a single anti-transferrin receptor 1 (TfR1)-antigen-binding antibody fragment linked to a therapeutic antibody, allowing engagement with TfR1 to transport the therapeutic antibody into the brain via receptor-mediated transcytosis. Methods: We compared Fc-silenced and Fc-competent variants of the Brainshuttle and the parental (non-shuttled) type II CD20 mAb, obinutuzumab in in vitro and in vivo (mouse and cynomolgus macaque) models. Endpoints assessed included B cell binding, B cell killing, tolerability, and ability to cross the BBB. Results: The Fc-silenced Brainshuttle construct showed a superior safety profile compared with the Fc-competent construct while maintaining the ability to cross the BBB and to deplete B cells in head-to-head comparisons in human and mouse in vitro and in mouse and cynomolgus macaque in vivo models. Conclusion: Together, our data provide a path forward for the future development of safe and efficacious brain-targeted B-cell-depleting therapies. Key points: The BBB hinders mAb-based brain disorder therapies A brain-targeted B-cell-depleting mAb for MS that efficiently crosses the BBB via hTfR1 was developed using Brainshuttle™ technology (1a and 1b) The Brainshuttle™-CD20 mAb was well tolerated (2a and 2b) and displayed B-cell-killing properties (1c), paving the way for future development and clinical translation of TfR1-targetingtherapies for increased brain penetration.