A novel GARP humanized mouse model for efficacy assessment of GARP-targeting therapies.

Although breakthroughs have been achieved with immune checkpoint inhibitors (ICI) therapy, some tumors do not respond to those therapies due to primary or acquired resistance. GARP, a type I transmembrane cell surface docking receptor mediating latent transforming growth factor-ß (TGF-ß) and abundantly expressed on regulatory T lymphocytes and platelets, is a potential target to render these tumors responsive to ICI therapy, and enhancing anti-tumor response especially combined with ICI. To facilitate these research efforts, we developed humanized mouse models expressing humanized GARP (hGARP) instead of their mouse counterparts, enabling in vivo assessment of GARP-targeting agents. We created GARP-humanized mice by replacing the mouse Garp gene with its human homolog. Then, comprehensive experiments, including expression analysis, immunophenotyping, functional assessments, and pharmacologic assays, were performed to characterize the mouse model accurately. The Tregs and platelets in the B-hGARP mice (The letter B is the first letter of the company's English name, Biocytogen.) expressed human GARP, without expression of mouse GARP. Similar T, B, NK, DCs, monocytes and macrophages frequencies were identified in the spleen and blood of B-hGARP and WT mice, indicating that the humanization of GARP did not change the distribution of immune cell in these compartments. When combined with anti-PD-1, monoclonal antibodies (mAbs) against GARP/TGF-ß1 complexes demonstrated enhanced in vivo anti-tumor activity compared to monotherapy with either agent. The novel hGARP model serves as a valuable tool for evaluating human GARP-targeting antibodies in immuno-oncology, which may enable preclinical studies to assess and validate new therapeutics targeting GARP. Furthermore, intercrosses of this model with ICI humanized models could facilitate the evaluation of combination therapies.

Humanized CD36 (hCD36) mouse model supports the preclinical evaluation of therapeutic candidates targeting CD36.

CD36 (also known as scavenger receptor B2) is a multifunctional receptor that mediates lipid uptake, advanced oxidation protein products, and immunological recognition, and has roles in lipid accumulation, apoptosis, as well as in metastatic colonization in cancer. CD36 is involved in tumor immunity, metastatic invasion, and therapy resistance through various molecular mechanisms. Targeting CD36 has emerged as an effective strategy for tumor immunotherapy. In this study, we have successfully generated a novel hCD36 mouse (Unless otherwise stated, hCD36 mouse below refer to homozygous hCD36 mouse) strain where the sequences encoding the extracellular domains of the mouse Cd36 gene were replaced with the corresponding human sequences. The results showed that the hCD36 mice only expressed human CD36, and the proportion of each lymphocyte was not significantly changed compared with wild-type mice. Furthermore, CD36 monoclonal antibody could significantly inhibit tumor growth after treatment. Therefore, the hCD36 mouse represent a validated preclinical mouse model for the evaluation of tumor immunotherapy targeting CD36.

Generation of influenza A viruses as live but replication-incompetent virus vaccines.

The conversion of life-threatening viruses into live but avirulent vaccines represents a revolution in vaccinology. In a proof-of-principle study, we expanded the genetic code of the genome of influenza A virus via a transgenic cell line containing orthogonal translation machinery. This generated premature termination codon (PTC)-harboring viruses that exerted full infectivity but were replication-incompetent in conventional cells. Genome-wide optimization of the sites for incorporation of multiple PTCs resulted in highly reproductive and genetically stable progeny viruses in transgenic cells. In mouse, ferret, and guinea pig models, vaccination with PTC viruses elicited robust humoral, mucosal, and T cell-mediated immunity against antigenically distinct influenza viruses and even neutralized existing infecting strains. The methods presented here may become a general approach for generating live virus vaccines that can be adapted to almost any virus.