(W1530-02-10) An “I” (Immunogenicity Risk Assessment) for an Eye (Ophthalmology Biologics)

Purpose: As new products are brought forward to the clinic for treatment of eye diseases, immunogenicity needs to be carefully considered, despite the reputation of the eye as an immune-privileged site. An Immunogenicity Risk Assessment is now considered to be an integral part of IND (Investigational new drug) applications to the FDA. Various strategies are employed to assess immunogenicity risk, each offering unique insights into the interplay between the biologic product and the immune system. In this context, three prominent approaches stand out: in silico prediction models, in vitro T cell assays, and MAPPs assays. We have developed and applied an in silico risk assessment platform called ISPRI, that can rapidly assess the immunogenic potential of a biologic, identifying key ‘clusters’ of immunogenic or tolerogenic potential that may be relevant to immune responses and for immunogenic clusters, that may also be modified to reduce immunogenicity. Here we apply ISPRI analysis to an ophthalmologic biologic that has been associated with intra-ocular inflammation (IOI) and anti-drug antibody responses (ADA). Brolucizumab is a humanized monoclonal single chain variable fragment (scFv) for the treatment of neovascular age-related macular degeneration.

Methods: We retrieved the amino acid sequence of brolucizumab, an scFv consisting of a variable heavy chain domain and a variable light chain domain. We then used ISPRI to assess its potential for immunogenicity. For each input sequence and domain of the scFv, ISPRI provides Tregitope-adjusted Immunogenicity Scores. The Tregitope-adjusted Immunogenicity Score can be used to predict the ADA response rate for novel antibody products using a regression model based on a set of clinical benchmark monoclonal antibodies whose observed ADA response rates are known.

Results: The ISPRI algorithm identified the areas of brolucizumab that could be contributing to the immunogenicity observed in the clinic. The variable light chain domain has a very high score as compared to many non-immunogenic antibodies. As a result, the ISPRI-generated combined score of the variable heavy and variable light chain domains of brolucizumab is in the upper range of the antibody immunogenicity scale. This score indicated that the biologic would likely be associated with ADA, as was observed in several clinical trials. According to the FDA label for this product, “After initiation of dosing, anti-brolucizumab antibodies were detected in at least one serum sample in 53% to 76% of patients treated with ...” the biologic, and “Intraocular inflammation was observed in 6% of patients with anti-brolucizumab antibodies detected during ... clinical trials.” Within the variable light domain, the ISPRI algorithm identified several hot spots, two of which scored very high on the scale. Deimmunization of these identified hot spots could have resulted in a less immunogenic therapeutic.

Conclusion: In this study, brolucizumab was evaluated and was shown to have an overall immunogenicity risk assessment performed by ISPRI that was consistent with clinical observations. This analysis of brolucizumab shows that it is necessary to not only consider the immunogenic potential of novel constructs as a whole, but also of individual components that might each have distinct T cell epitope characteristics. The use of in silico tools such as the ISPRI platform proves to be an essential step in the development of biological therapies as evidenced by this case study.

References: 1. Liu A. Novartis calls off 3 Beovu trials testing more frequent dosing on concerns of vision-threatening side effect. 2021 Jun.
2. Busch M, Pfeil JM, Dähmcke M, Brauckmann T, Großjohann R, Chisci V, et al. Anti-drug antibodies to brolucizumab and ranibizumab in serum and vitreous of patients with ocular disease. Acta Ophthalmol. 2022;100(8).
3. Forrester J V., Xu H. Good news-bad news: The Yin and Yang of immune privilege in the eye. Vol. 3, Frontiers in Immunology. 2012.
4. Monés J, Srivastava SK, Jaffe GJ, Tadayoni R, Albini TA, Kaiser PK, et al. Risk of Inflammation, Retinal Vasculitis, and Retinal Occlusion–Related Events with Brolucizumab: Post Hoc Review of HAWK and HARRIER. In: Ophthalmology. 2021.
5. Kearns JD, Wassmann P, Olgac U, Fichter M, Christen B, Rubic-Schneider T, et al. A root cause analysis to identify the mechanistic drivers of immunogenicity against the anti-VEGF biotherapeutic brolucizumab. Sci Transl Med. 2023.