Bioengineered iPSC-derived human macrophages with increased angiotensin-converting enzyme (ACE) expression suppress solid tumor growth.

The potential of the immune system to decrease cancer progression is widely recognized and has led to the development of innovative anti-cancer immunotherapies. Here, we studied human macrophages derived from genetically engineered iPSCs (iMac) with angiotensin-converting enzyme (ACE) expression regulatable by a doxycycline (dox)-inducible promoter as a novel anti-cancer immunotherapy. Increased ACE expression in iMac (cells now termed ACE-iMac) augments polarization towards an M1 macrophage phenotype characterized by increased production of proinflammatory cytokines, reactive oxygen species, nitric oxide, and an RNA profile indicating an aggressive immune response. ACE-iMac kills tumor cells in vitro significantly better than iMac. In vivo, studies using tumor xenografts for melanoma, breast cancer, and head and neck squamous cell carcinoma (HNSCC) showed a highly significant 3.4- to 7.2-fold reduction in solid tumor size following ACE-expressing ACE-iMac immunotherapy as compared to results with iMac. To further investigate the impact of ACE on human anti-tumor responses, we developed a humanized BLT-NSG mouse model with a fully functional adaptive immune system. Here, ACE-iMac treatment significantly reduced the growth of human melanoma xenografts by enhancing the activation of human T cells and NK cells. In conclusion, enhancing ACE expression in human-derived macrophages (ACE-iMac) greatly amplifies their anti-cancer phenotype, offering a compelling new therapeutic strategy with the potential to improve clinical outcomes for cancer patients.