|Strain Name||C57BL/6-Cd274tm1(CD274)Ctla4tm1(CTLA4)/Bcgen||Common Name||B-hPD-L1/hCTLA4 mice|
CTLA4 (Cytotoxic T-lymphocyte-associated protein 4,CD152)
PD-L1 (Programmed cell death ligand-1), also known as B7-H1 and CD274, is mainly expressed in antigen-presenting cells (APCs) and activated T cells, and is one of the two ligands of PD-1. The interaction between PD1 and PD-L1 plays an important role in the negative regulation of the immune response. PD-L1 is highly expressed in a variety of solid tumors. PD-1 and PD-L1 interactions can reduce T cell activation and promote tumor immune escape. The PD-1/PD-L1 signaling pathway can be blocked and antitumor immune response can be restored by using by anti-PD-1 or anti-PD-L1 antibodies to block the binding of PD1 to PD-L1. CTLA4 (cytotoxic T-lymphocyte-associated protein 4), also known as CD152, competitively binds to B7-1 (CD80) and B7-2 (CD86) on Antigen-Presenting Cells (APCs) to block the T cell activating signal by B7 and CD28 (on T cells) interaction. The inhibition of CTLA4 by its inhibitory antibodies enhances T cell activity. The CTLA4 antibody is the first FDA-approved antibody to treat advanced melanoma.
Protein expression analysis
Strain specific PD-L1 and CTLA4 expression analysis in homozygous B-hPD-L1/hCTLA4 mice by flow cytometry.
Splenocytes were collected from WT and homozygous B-hPD-L1/hCTLA4 (H/H) mice stimulated with anti-CD3ε in vivo, and analyzed by flow cytometry with species-specific anti-PD-L1 and anti-CTLA4 antibody. Mouse PD-L1 and CTLA4 were detectable in WT mice. Human PD-L1 and CTLA4 were exclusively detectable in homozygous B-hPD-L1/hCTLA4 but not WT mice.
Combination therapy of anti-human PD-L1 antibody and anti-human CTLA4 antibody
Antitumor activity of anti-human PD-L1 antibody combined with anti-human CTLA4 antibody in B-hPD-L1/hCTLA4 mice.
(A) Anti-human PD-L1 antibody combined with anti-human CTLA4 antibody inhibited MC38-hPD-L1 tumor growth in B-hPD-L1/hCTLA4 mice. Murine colon cancer MC38-hPD-L1 cells were subcutaneously implanted into homozygous B-hPD-L1/hCTLA4 mice (female, 6-7 week-old, n=6). Mice were grouped when tumor volume reached approximately 100 mm3, at which time they were treated with atezolizumab and ipilimumab with doses and schedules indicated in panel A. (B) Body weight changes during treatment. As shown in panel A, combination of atezolizumab and ipilimumab shows more inhibitory effects than individual groups, demonstrating that the B-hPD-L1/hCTLA4 mice provide a powerful preclinical model for in vivo evaluating combination therapy efficacy of hPD-L1 antibodies and hCTLA4 antibodies. Values are expressed as mean ± SEM.