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