2024 AIChE Annual Meeting
(88f) Generation of Species Cross-Reactive CD98hc Antibodies Using Directed Evolution
Authors
Wu, W., University of Michigan
Akin, E., University of Michigan
Tessier, P., University of Michigan
CD98hc, the heavy chain of the large neutral amino acid transporter, has been identified as an attractive target for the transport of therapeutics across the blood-brain barrier (BBB). However, chemical and structural differences between mouse and human CD98hc prevent species cross-reactive binding of anti-CD98hc antibodies, requiring CD98hc transgenic rodents for preclinical studies, which is not possible in some cases and generally impedes clinical translation. In this work, we identify CD98hc epitopes compatible with species cross-reactive binding and use directed evolution to introduce mouse cross-reactive binding in an existing anti-human CD98hc antibody. Random mutations were introduced into one of the complementarity-determining regions (CDRs) of an existing human CD98hc antibody, specifically heavy chain CDR3 (HCDR3). This panel of mutants was sorted for simultaneous binding to both mouse and human CD98hc. A lead clone with micromolar affinity to mouse and human CD98hc was identified through this process, which was subsequently affinity matured by mutagenizing additional CDRs (HCDR1 and HCDR2) and screening for variants with increased affinity using yeast-surface display. This resulted in the isolation of antibodies with nanomolar affinities to both mouse and human CD98hc. These species cross-reactive antibodies are currently being evaluated as bispecific CD98hc antibodies for brain shuttling applications.