Characterization of human cancer xenografts in humanized mice

Abstract

BackgroundPreclinical evaluation of drugs targeting the human immune system has posed challenges for oncology researchers. Since the commercial introduction of humanized mice, antitumor efficacy and pharmacodynamic studies can now be performed with human cancer cells within mice bearing components of a human immune system. However, development and characterization of these models is necessary to understand which model may be best suited for different agents.MethodsWe characterized A375, A549, Caki-1, H1299, H1975, HCC827, HCT116, KU-19–19, MDA-MB-231, and RKO human cancer cell xenografts in CD34+humanized non-obese diabetic-scid gamma mice for tumor growth rate, immune cell profiling, programmed death ligand 1 (PD-L1) expression and response to anti-PD-L1 therapy. Immune cell profiling was performed using flow cytometry and immunohistochemistry. Antitumor response of humanized xenograft models to PD-L1 therapy was performed using atezolizumab.ResultsWe found that CD4+and CD8+T-cell composition in both the spleen and tumor varied among models, with A375, Caki-1, MDA-MB-231, and HCC827 containing higher intratumoral frequencies of CD4+and CD8+T cells of CD45+cells compared with other models. We demonstrate that levels of immune cell infiltrate within each model are strongly influenced by the tumor and not the stem cell donor. Many of the tumor models showed an abundance of myeloid cells, B cells and dendritic cells. RKO and MDA-MB-231 tumors contained the highest expression of PD-L1+tumor cells. The antitumor response of the models to atezolizumab was positively associated with the level of CD4+and CD8+tumor-infiltrating lymphocytes (TILs).ConclusionsThese data demonstrate that there are tumor-intrinsic factors that influence the immune cell repertoire within tumors and spleen, and that TIL frequencies are a key factor in determining response to anti-PD-L1 in tumor xenografts in humanized mice. These data may also aid in the selection of tumor models to test antitumor activity of novel immuno-oncology or tumor-directed agents.

Testing Cancer Immunotherapy in a Human Immune System Mouse Model: Correlating Treatment Responses to Human Chimerism, Therapeutic Variables and Immune Cell Phenotypes

“…The majority of the non-T cells in tumors of our HIS-BRGS mice was of the myeloid lineage ( 23 ). Altogether, and consistent with other studies in HIS-mice ( 44 , 84 ), these data suggest the tumors in our HIS-BRGS model generally recapitulate their unique TME in regard to immune infiltration.…”

“…In summary, we provide ample evidence that human xenografts grow in the multi-lineage HIS models generated from human HSCs. As similarly observed by other groups ( 50 , 84 ), we achieved high and reproducible tumor take rates in our HIS-BRGS mice.…”

“…Indeed, SCLC tumors “A-D” had almost no hCD45 + infiltration as expected for this well-known “cold” tumor ( 86 , 87 ). We also compared right versus left flank tumors and observed quite consistent hCD45 + infiltration within an individual HIS-mouse, although the tumors were often quite different in size ( Supplementary Figure 4 ) ( 44 , 84 ).…”

Antibody-Based Targeting of Interferon-Beta-1a Mutein in HER2-Positive Cancer Enhances Antitumor Effects Through Immune Responses and Direct Cell Killing

“…FOXP3 stained cells, presumed to be regulatory T cells were significantly decreased by a third compared to vehicle control. Rios-Doria et al characterized several xenograft models using humanized mice and revealed that the antitumor response of the models to immunotherapy was positively associated with the induced levels of CD4 and CD8 tumor-infiltrating lymphocytes ( Rios-Doria et al, 2020 ). Moreover, CD8 T cells were essential for the antitumor immune response of the murine IFN-β-immunocytokine ( Yang et al, 2014 ).…”

Glioblastoma Organoids: Pre-Clinical Applications and Challenges in the Context of Immunotherapy

“…The HU-CD34 model has been successfully combined with several cell line-derived xenografts and PDXs of different cancer types (137)(138)(139). Although a perfect HLA match between CD34+ HSC donor and tumor patient is impossible, a partial HLA match did not negatively affect tumor growth in recent reports on PDXs (139,140).…”