The goal of our study is to establish mouse models for fast in vivo efficacy studies of biologics, such as CAR-T and therapeutic antibody candidates. B-NDG mice (NOD-Prkdcscid Il2rgtm1/Bcgen) were independently developed by Biocytogen to knockout the IL2rg gene in the NOD-SCID mouse background. Here we demonstrated that B-NDG, as one of the most severely immunodeficient mice, completely lack mature T, B, and NK cells, and were deficient in cytokine signaling.

We have established more than 24 CDX models using B-NDG mice, including human solid tumor and blood tumor cell lines, such as bladder carcinoma, breast cancer, colon carcinoma, colorectal adenocarcinoma, glioblastoma, liver cancer, lung carcinoma, and various leukemia and lymphoma cell lines. We have previously demonstrated that B-NDG mice inoculated with human tumor cells can be used for CAR-T therapy evaluation.

In addition, B-NDG mice are one of the best models for human immune system reconstitution using either PBMC or CD34+ hematopoietic stem cells. Human PBMCs reconstitute very well in B-NDG mice, with the percentage of hCD45+ cells reaching well over 50% within five weeks; moreover, the majority of these cells were CD3+ T lymphocytes. Human PBMC reconstituted B-NDG mice have also been successfully used for multiple therapeutic antibody efficacy studies. In order to reduce the GvHD, we have generated B-NDG B2M mice, on which the B2M gene was knocked-out. B-NDG B2M mice have a longer therapeutic window for PBMC reconstitution when compared with B-NDG mice, and have been successfully used for antibody efficacy studies.

Other than PBMCs, human CD34+ hematopoietic stem cells have been successfully grafted in B-NDG mice, in which all major human myeloid and lymphoid lineage cell types were fully developed, reconstituting a functional human immune system. At 10 weeks post CD34+ cell implantation, the percentage of hCD45+ cells reached over 25%, containing human T, B, and NK cells. These CD34+ reconstituted B-NDG mice are powerful tools for the fields of hematopoiesis, immunology, and autoimmunity, as well to evaluate clinically-relevant therapeutic antibody drugs in vivo.

Without any significant rejection of human-derived cells, the B-NDG mouse becomes an ideal model for transplantation of PDX, which retain the high heterogeneic properties typical of human tumor tissues. Using B-NDG mice, we have successfully established more than 300 PDX models, covering breast, colon, gastric, leukemia, lung, pancreatic cancers, and particularly blood tumor samples. Here we provide examples that use human immune reconstituted B-NDG PDX models to successfully evaluate the in vivo efficacy of human immune checkpoint antibodies in mono-or in combination therapy. In conclusion, we have developed more powerful and predictive mouse models for preclinical pharmacological evaluation of CAR-T and therapeutic antibodies.

Citation Format: Qingcong Lin, Madeline Lee, Yanan Guo, Tian Gan. The human immune system reconstituted B-NDG mouse models are ideal tools for CAR-T and therapeutic antibody preclinical efficacy evaluation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1052.