Translatable PK/PD with HSA/hFcRn mouse model

The HSA/hFcRn mouse model has an extensive track record

This model's key features result in a more translatable half-life of compounds targeting HSA/FcRn in the humanized mouse than in wild type mouse, as demonstrated by:

• Viuff et al., who have shown that the HSA/hFcRn mouse model improves the translatability of PK assessment of therapeutics with extended half-life via FcRn recycling and/or HSA binding (https://pubmed.ncbi.nlm.nih.gov/26699424/)
• Mandrup et al., who demonstrated that the half-life of a bispecific T-cell engager, the Albu-LiTE-HB, was 60-fold longer when fused to HSA and due to higher affinity with the humanized FcRn (https://pubmed.ncbi.nlm.nih.gov/33686177/). Read our commentary here‍
• ‍Fuchs et al., who generated and tested genetic fusions of human albumin and the SARS-CoV-2 cellular receptor ACE2, and showed that it was possible to extend the half-life of SARS-CoV-2 decoys in our HSA/hFcRn mouse model (https://pubmed.ncbi.nlm.nih.gov/36162760/). Read our commentary here
• Vantourout et al., who demonstrated that AlbuBinder 1 could extend the half-life of different conjugates over 20-fold by binding to humanised serum albumin, representing a promising strategy to improve drug delivery and treatment compliance (https://pubmed.ncbi.nlm.nih.gov/33523652/)
• Duran-Güell et al., who investigated the protective role of albumin against TNFα-induced liver injury and revealed that albumin inhibits the lysosomal cathepsin B leakage and the subsequent cytochrome c release to the cytosol, leading to decreased caspase-3 activity (https://pubmed.ncbi.nlm.nih.gov/33496031/)
• Kim et al., who fused a human serum albumin-specific protein binder to human interleukin 15 and demonstrated that its half-life was extended by 40-fold in hSA/hFcRn mice compared to WT mice. This construct was also shown to display anti-tumour activity (https://pubmed.ncbi.nlm.nih.gov/35905933/)
• Ma et al., who showed that FcRn-antibodies can lead to a reduction in albumin levels either through FcRn degradation in lysosomes or by direct competition between antibodies and albumin for FcRn binding (https://pubmed.ncbi.nlm.nih.gov/38713534/)

Here are client posters using the HSA/hFcRn mouse model:

• Avacta Group poster, presented at AACR2021: Pharmacokinetic and Biodistribution of Formatted Affimer® Biotherapeutics Targeting PD-L1
• Crescendo Biologics poster, presented at AACR2024: CB307: A dual targeting costimulatory Humabody ® VH therapeutic for treating PSMA-positive tumors

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Intercrossed models that are available or under development

In order to expand the range of application of our HSA/hFcRn mouse model, we are working on the following intercrosses:

• hFcγR/HSA/hFcRn for PK assessment of Fc-mediated function of therapeutic antibodies
• hTFRC/HSA/hFcRn to enable translatable PK and biodistribution of compounds targeting TFRC
• HSA/hFcRn/Rag1-KO to assess compounds' half-life and perform anti-tumor efficacy studies in a human tumor model‍
• BRGSF-HIS/hFcRn model with reconstituted human immune system with humanized FcRn to perform efficacy, safety and PK studies for immunomodulating therapies