The huPD-1/huCD19 mouse is a dual-gene humanized model obtained by crossing the huPD-1 mouse (Catalog No.: C001524) with the huCD19 mouse (Catalog No.: C001731). This model is suitable for studying drug screening, pharmacodynamic evaluation, safety assessment, tumor immunotherapy, and the underlying mechanisms of the immune system related to PD-1/CD19.

The huPD-1/huFcRn mice are a dual-gene humanized model obtained by mating huPD-1 mice (Catalog Number: C001524) with huFcRn(FCGRT) mice (Catalog Number: C001701). This model is applicable to the screening of human IgG antibody drug candidates, as well as the evaluation of pharmacology, pharmacodynamics, and pharmacokinetics. It serves as a valuable tool for advancing research in tumor immunotherapy and the mechanisms of the immune system.

Programmed cell death protein 1 (PDCD1/PD-1) is a member of the B7-CD28 costimulatory receptor family. It is an inhibitory receptor expressed on activated T cells and plays a role in regulating the function of effector T cells, including CD8+ T cells, and promoting the differentiation of CD4+ T cells into regulatory T cells. PD-1 is expressed in a variety of tumors and plays an important role in antitumor immunity. In addition, PD-1 is involved in the defense against autoimmune diseases and has inhibitory effects on antitumor and antimicrobial immunity ^[1]. PD-1 binds to programmed death ligands 1 and 2 (PD-L1 and PD-L2) to inhibit T cell activation, reduce the production of corresponding cytokines, and regulate T cell survival ^[2]. Drugs targeting this pathway can reactivate T cells to activate antitumor immune responses ^[3]. The Vascular Endothelial Growth Factor (VEGF) family is a group of particular endothelial growth factors intimately associated with angiogenesis. These factors promote increased vascular permeability, extracellular matrix degeneration, vascular endothelial cell migration and proliferation, and are capable of stimulating angiogenesis and increasing the permeability of existing vessels. As such, they play a pivotal role in normal vascular development and wound healing. The VEGF family comprises VEGFA, VEGFB, VEGFC, VEGFD, VEGFE, and PLGF ^[4]. Of these, VEGFA is the most commonly targeted in research related to neovascular ophthalmic diseases due to its crucial role in the proliferation, migration, and formation of endothelial cell microvessels ^[5]. Overexpression of VEGFA in the eye can result in abnormal vascular growth and leakage, leading to various ophthalmic diseases such as Age-Related Macular Degeneration (AMD), Diabetic Retinopathy (DR), and corneal neovascularization ^[5-6]. The progression of solid tumors depends on vascularization and angiogenesis within malignant tissues, with VEGFA playing a crucial role among various pro-angiogenic factors. The VEGFA gene is upregulated in many known tumors, correlating with tumor staging and progression. Blocking VEGFA may lead to vascular network regression, inhibiting tumor growth ^[7]. Thus, VEGFA is an important target for anti-angiogenic cancer therapies. The B6-hPD-1/hVEGFA mouse is a humanized model obtained by crossbreeding hPD-1 mice (Catalog No. C001524) with B6-hVEGFA mice (Catalog No. C001555). This model can be used for research in drug development, efficacy and safety evaluation, tumor immunotherapy evaluation, and immune system mechanisms related to human PD-1/VEGFA.

PD-1 and CTLA-4 are checkpoint receptors that critically modulate T cell immunity. The genes PDCD1 and CTLA4 encode PD-1 and CTLA-4 respectively, with CTLA4 expression largely restricted to T cells, while PDCD1 is evident in activated T cells, B cells, and myeloid populations ^[1]. These transmembrane proteins function as key negative regulators of T cell activation ^[2]. CTLA-4 primarily operates in lymphoid tissues during early immune responses to restrain T cell proliferation, whereas PD-1 predominantly acts in peripheral tissues during the effector phase to dampen T cell activity and limit immunopathology, particularly in chronically stimulated or ‘exhausted’ T cells ^[2-3]. Aberrant regulation of PD-1 and CTLA-4 is implicated in the pathogenesis of cancers, including melanoma, non-small cell lung cancer, and renal cell carcinoma, as well as chronic viral infections such as hepatitis B and C ^[1][4]. Clinically, monoclonal antibodies targeting CTLA-4 (e.g., ipilimumab) and PD-1 (e.g., nivolumab, pembrolizumab) are established immunotherapeutic agents that enhance anti-tumor responses. By blocking these negative signaling pathways, these monoclonal antibodies restore the anti-tumor activity of T cells, significantly enhancing anti-tumor responses ^[1-2]. These drug applications have not only improved the treatment outcomes for various cancers but also offer new strategies for the treatment of chronic viral infections. B6-hPD-1/hCTLA4 mouse is a dual humanized model of PD1 and CTLA4 constructed by humanizing the mouse Pdcd1 gene based on the CTLA4 humanized mouse model (Catalog No. C001413), due to the fact that the mouse Pdcd1 gene and Ctla4 gene are on the same chromosome. These mice express human CTLA4 and PDCD1 genomic sequences under the control of mouse promoters. This model is capable of reproducing the human PD-1/CTLA4 signaling pathway and is a valuable tool for studying cancers and chronic viral infections. Furthermore, this model provides a powerful preclinical research platform for evaluating the efficacy and mechanism of therapeutic drugs targeting the PD-1/CTLA4 signaling pathway.

The huPD-1/huTNF(B6;D1) mice are a dual-gene humanized model obtained by mating huPD-1 mice (Catalog number: C001524) with huTNF(DBA/1) mice (Catalog number: C001587). This model is suitable for research on drug screening, efficacy and safety evaluation, immunotherapy, and immune system mechanisms related to PD-1 and TNF.

Programmed cell death protein 1 (PDCD1/PD-1) is a member of the B7-CD28 costimulatory receptor family. It is an inhibitory receptor expressed on activated T cells and plays a role in regulating the function of effector T cells, including CD8+ T cells, and promoting the differentiation of CD4+ T cells into regulatory T cells. PD-1 is expressed in a variety of tumors and plays an important role in antitumor immunity. In addition, PD-1 is involved in the defense against autoimmune diseases and has inhibitory effects on antitumor and antimicrobial immunity ^[1]. Programmed cell death 1 ligand 1 (PD-L1), also known as cluster of differentiation 274 (CD274) or B7 homolog 1 (B7H1), is an immune inhibitory receptor ligand. PD-L1 is a type I transmembrane protein with immunoglobulin V-like (IgV) and C-like (IgC) structural domains and is expressed by hematopoietic and non-hematopoietic cells, including T cells, B cells, and various types of tumor cells ^[2]. PD-L1 can bind to the PD-1 on the surface of CD8+ T cells, inhibiting the activity of CD8+ T cells. This interaction can prevent the immune system from damaging normal tissues, but it can also be used by tumor cells to escape immune surveillance. Monoclonal antibodies that competitively bind to PD-L1 can relieve the immune function inhibition mediated by the binding of PD-1 and PD-L1. This can reactivate CD8+ T cells, triggering the human body's anti-tumor immune response ^[3]. Therefore, development of antibody drugs targeting PD-1 and PD-L1 is a hot area in tumor immunotherapy ^[3-5]. The Vascular Endothelial Growth Factor (VEGF) family is a group of particular endothelial growth factors intimately associated with angiogenesis. These factors promote increased vascular permeability, extracellular matrix degeneration, vascular endothelial cell migration and proliferation, and are capable of stimulating angiogenesis and increasing the permeability of existing vessels. As such, they play a pivotal role in normal vascular development and wound healing. The VEGF family comprises VEGFA, VEGFB, VEGFC, VEGFD, VEGFE, and PLGF ^[6]. Of these, VEGFA is the most commonly targeted in research related to neovascular ophthalmic diseases due to its crucial role in the proliferation, migration, and formation of endothelial cell microvessels ^[7]. Overexpression of VEGFA in the eye can result in abnormal vascular growth and leakage, leading to various ophthalmic diseases such as Age-Related Macular Degeneration (AMD), Diabetic Retinopathy (DR), and corneal neovascularization ^[7-8]. The progression of solid tumors depends on vascularization and angiogenesis within malignant tissues, with VEGFA playing a crucial role among various pro-angiogenic factors. The VEGFA gene is upregulated in many known tumors, correlating with tumor staging and progression. Blocking VEGFA may lead to vascular network regression, thereby inhibiting tumor growth ^[9]. Thus, VEGFA is an important target for anti-angiogenic cancer therapies. B6-hPD-1/hPD-L1/hVEGFA mouse is a triple-gene humanized model generated by crossing B6-hPD-1/hPD-L1 mice (Catalog No.: I001202) with B6-hVEGFA mice (Catalog No.: C001555). This model serves as a valuable tool for research on cancer immunotherapy and can also be used for the screening, development, and preclinical evaluation of PD-1/PD-L1/VEGFA-targeted drugs.