Harnessing human immune system models to validate NADPH oxidase 1 inhibition as treatment for hepatocellular...

NADPH oxidase 1 inhibition (NOX1i) has shown to alter the tumor microenvironment in conventional mouse models for hepatocellular carcinoma (HCC). However, clinical translation is hampered by low translatability of these models.

We developed two novel human immune system (HIS) mouse models, co-transplanted with orthotopic human HCC cells, to investigate NOX1i in the context of human HCC and human adaptive (T cell-HIS-HCC) or innate (Myeloid-HIS-HCC) immune responses. Mice received NOX1i or vehicle twice per week for 3 weeks. Results were validated in ex vivo patient-derived precision-cut tumor slices (PCTS).

T cell-HIS-HCC mice were mainly reconstituted with human T cells. Interestingly, the expression of cytokines and markers involved in both cancer progression and anti-tumor immunity was significantly lower in tumors of NOX1i-treated mice. In the Myeloid-HIS-HCC model, humanization in livers and tumors was dominated by macrophages. Significantly lower human immune cells were observed in tumors of NOX1i-treated Myeloid-HIS-HCC mice, in line with reduced VCAM1 and ICAM1 expression. NOX1i-treated Myeloid-HIS-HCC mice showed a similar shift in tumor-promoting cytokines and immune checkpoints as NOX1i-treated T cell-HIS-HCC mice. Moreover, gene expression of tumor-associated macrophage, HCC and proliferation markers tended to be lower in tumors of NOX1i-treated Myeloid-HIS-HCC mice. Ex vivo patient-derived PCTS treated with NOX1i also demonstrated lower gene expression of pro-tumorigenic cytokines and tumor-promoting markers.

Our data show that NOX1i modulates the tumor-immune microenvironment in human immune system HCC models, and might hold potential in combination therapy to rebalance the dysregulated immune profile in HCC.