Abstract 6258: Development of humanized patient-derived xenograft models for triple negative breast cancer
Authors: Her Yujeong , Son Hye Yeon , Kim Ju Hee , Heo Woo Hang , Quan Mingji , Li Songbin , Moon Hyeong Gon 
Published: June 2022

Abstract
As a new promising in vivo platform for personalized treatment in the field of cancer research, the most improved way has been adopted by far is grafting patient-derived xenograft (PDX) to humanized mouse models which represent the unique features of interaction with human immune system and tumor microenvironment (TME). Here, we engineered triple negative breast cancer (TNBC) humanized PDX mouse (Hu-PDX) model to observe human immune system and tumor growth in TME. In addition, we analyzed gene ontology of PDX isolated from hu or non-humanized mouse model.
Method: Human CD34+hematopoietic stem cells (HSCs) derived from cord blood is reconstructed into mature human leukocytes (hCD45+) in NOD.Cg-PrkdcscidIL2γgtm1 Sug (NOG) mice. TNBC PDX tumors are established it with unmatched human leukocyte antigen (HLA) genotypes, confirmed by that hCD45+ engraftment levels did not exceed 20-30% in the peripheral blood of mice. To be repopulated functional human T cells in xenograft models with severely depleted thymus, hCD34-PBMC cells are directly intravenously injected into tail vein of humanized mice followed by hCD34+cells injected without the onset of graft-versus-host disease (GVHD). The growth and gene expression of TNBC PDX tumors, as well as engrafted human immune population including T, B, natural killer (NK) cells and myeloid cells in TME, are monitored and investigated in both hu and non-hu-mice model.
Results: Human immune reconstruction of cells, of the lymphoid as well as myeloid lineages, has been successfully accomplished in peripheral blood, spleen, and bone marrow over time in TME. Although the number of human mature leukocytes was gradually decreased in mice by 17 weeks, humanized mice have enabled studies of human immunity and TME in limitation period. Also, one of remaining limitations is unable to positive and negative selection of human T cells in the humanized mouse thymus and required to human major histocompatibility complex (MHC) molecules in humanized mice. To overcome this barrier, additional stimulation factor for generating functional T cells have successfully engrafted by transferring hCD34-PBMC cells. Moreover, tumor infiltrating human lymphocytes (TILs) have obviously detected in Hu-PDX model, although the differences tumor growth rate was not significantly monitored, compared with non-humanized mice. Interestingly, the analysis of gene ontology; biological process, cellular component and molecular function, ribosomal relevant proteins, not immune related genes, were highly up-regulated in TNBC PDX humanized in comparison to non-humanized mouse model.
Conclusion: Humanized PDX model will contribute to studies more efficiently for the machinery underlying immunological response in breast tumor microenvironment. Furthermore, it might be an important unknown mechanism that the effect of elevated cancer-related ribosomal proteins expression within hu immune-TME.
Citation Format: Yujeong Her, Hye Yeon Son, Ju Hee Kim, Woo Hang Heo, Mingji Quan, Songbin Li, Hyeong Gon Moon. Development of humanized patient-derived xenograft models for triple negative breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6258.