Protein deimmunization via structure‐based design enables efficient epitope deletion at high mutational loads

Anti‐drug immune responses are a unique risk factor for biotherapeutics, and undesired immunogenicity can alter pharmacokinetics, compromise drug efficacy, and in some cases even threaten patient safety. To fully capitalize on the promise of biotherapeutics, more efficient and generally applicable protein deimmunization tools are needed. Mutagenic deletion of a protein's T cell epitopes is one powerful strategy to engineer immunotolerance, but deimmunizing mutations must maintain protein structure and function. Here, EpiSweep, a structure‐based protein design and deimmunization algorithm, has been used to produce a panel of seven beta‐lactamase drug candidates having 27–47% reductions in predicted epitope content. Despite bearing eight mutations each, all seven engineered enzymes maintained good stability and activity. At the same time, the variants exhibited dramatically reduced interaction with human class II major histocompatibility complex proteins, key regulators of anti‐drug immune responses. When compared to 8‐mutation designs generated with a sequence‐based deimmunization algorithm, the structure‐based designs retained greater thermostability and possessed fewer high affinity epitopes, the dominant drivers of anti‐biotherapeutic immune responses. These experimental results validate the first structure‐based deimmunization algorithm capable of mapping optimal biotherapeutic design space. By designing optimal mutations that reduce immunogenic potential while imparting favorable intramolecular interactions, broadly distributed epitopes may be simultaneously targeted using high mutational loads. Biotechnol. Bioeng. 2015;112: 1306–1318. © 2015 Wiley Periodicals, Inc.