Physicochemical developability insights into human Fab fragments with extended hypervariable loops.

Human antibodies with extended complementarity-determining regions (CDRs) can offer distinctive therapeutic opportunities by enabling binding to difficult targets. However, potential developability issues could pose problems for pharmaceutical development. Here, we used integrated experimental and computational workflows to analyze five human Fabs with a long third CDR in their heavy chains (CDR-H3). We assessed their secretion, homogeneity, conformational stability, colloidal stability, and non-specific binding, and complemented these analyses with molecular dynamics simulations to probe conformational dynamics and interpret experimental observations. We show that human antibodies with extended CDR-H3s display general sequence-dependent features and liabilities that are not necessarily determined by CDR-H3 length, underscoring the need for a mechanistically informed development strategy.