Antibody optimization enabled by artificial intelligence predictions of binding affinity and naturalness
Sharrol T. BachasiD, Goran RakoceviciD, David SpenceriD, Anand V. SastryiD, Robel Gemechu HaileiD, John M. SuttoniD, George W. Kasun, Andrew L. StachyraiD, Jahir M. GutierreziD, Edriss YassineiD, Borka Medjo, Vincent BlayiD, Christa Kohnert, Jennifer T. Stanton, Alexander Brown, Nebojša Tijanić, Cailen M. McCloskey, Rebecca Viazzo, Rebecca Consbruck, Hayley Carter, S. G. LEVINEiD, Shaheed A. AbdulhaqqiD, Jacob D. ShauliD, Abigail B. VenturaiD, Randal S. OlsoniD, , Roberto SpreaficoiD
Abstract
Traditional antibody optimization approaches involve screening a small subset of the available sequence space, often resulting in drug candidates with suboptimal binding affinity, developability or immunogenicity. Based on two distinct antibodies, we demonstrate that deep contextual language models trained on high-throughput affinity data can quantitatively predict binding of unseen antibody sequence variants. These variants span a KD range of three orders of magnitude over a large mutational space. Our models reveal strong epistatic effects, which highlight the need for intelligent screening approaches. In addition, we introduce the modeling of "naturalness", a metric that scores antibody variants for similarity to natural immunoglobulins. We show that naturalness is associated with measures of drug developability and immunogenicity, and that it can be optimized alongside binding affinity using a genetic algorithm. This approach promises to accelerate and improve antibody engineering, and may increase the success rate in developing novel antibody and related drug candidates.
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Abstract summary
Claude Opus 5.5 · xhigh effort · 18 Oct 2026 · from the abstract
Language models trained on high-throughput affinity data predict KD of unseen antibody variants across three orders of magnitude, and a "naturalness" score can be optimised alongside affinity.
Antibody optimisation normally screens a small slice of sequence space, so candidates can carry weak affinity or poor developability and immunogenicity. Learning affinity directly from large mutational libraries, and adding a score for resemblance to natural immunoglobulins, lets both properties be searched at once.
Key results
SuggestedContextual protein language models trained on high-throughput affinity measurements predict binding of antibody variants they were not trained on, quantitatively rather than as a ranking.
Demonstrated for two distinct antibodies, over variants covering a KD range of three orders of magnitude across a large mutational space; no correlation, error or held-out split is reported in the abstract. · Abstract
SuggestedBinding across the mutational libraries shows strong epistasis, so mutations cannot be assessed independently.
Reported as a model finding used to argue for guided rather than random screening; no magnitude, fraction of epistatic pairs or statistics are given. · Abstract
SuggestedA "naturalness" score for similarity to natural immunoglobulins tracks developability and immunogenicity measures and can be co-optimised with affinity by a genetic algorithm.
Stated as an association with developability and immunogenicity metrics; neither the metrics, the correlation strength, nor experimental results for the co-optimised variants appear in the abstract. · Abstract
Methods, data and reproducibility
Deep contextual language models were trained on high-throughput binding data from mutational libraries of two antibodies to predict KD of unseen variants. A separate naturalness model scores how closely a variant resembles natural immunoglobulins, and a genetic algorithm searches sequence space for variants scoring well on affinity and naturalness together.
- high-throughput binding affinity measurements over a large mutational space for two antibodies · n = 2 antibodies; variants spanning a KD range of three orders of magnitude
- Methods & tools
- deep contextual language model, genetic algorithm
- Reproducibility gaps
- No repository, dataset release, model architecture or library deposition is named in the abstract.
Limitations (2)
- Only two antibodies underlie the affinity results, with no library size, accuracy metric or held-out evaluation described in the abstract. · noted in this summary
- Naturalness is linked to developability and immunogenicity by assertion; no effect sizes, and no experimental characterisation of genetic-algorithm outputs, are reported here. · noted in this summary
Who should read:Read this if you engineer antibodies and want sequence models that score affinity and resemblance to natural immunoglobulins jointly instead of screening a narrow library slice.
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