1142 Generation of tumor-killing iPSC-macrophages through the genetic interrogation of CD47-SIRPa don’t eat me receptor pathway
Year: 2024
Type: conference-abstract
Abstract: Background Albeit the remarkable success of treating blood cancers with chimeric antigen receptor (CAR) T cell therapy, solid tumor cancers largely remain resistant to current immunotherapies. Macrophages within the tumor microenvironment (TME) are often polarized into pathogenic tumor-associated macrophages (TAMs), implicated in the inhibition of cytotoxic lymphocytes and blockade of macrophage-driven antitumor functions. Although TAMs are often highly involved in growth and survival of the tumor, macrophages have unique access to the TME and are highly communicative to surrounding immune cells, making them an attractive candidate for solid tumor immunotherapy. Many tumors over-express the ‘don’t eat me’ receptor CD47, recognized by macrophage receptor SIRPa. When SIRPa binds to CD47, it blocks macrophage-driven phagocytosis, thus protecting CD47+ cells from destruction. Methods To overcome this, we hypothesized knocking-out the ‘don’t eat me’ receptor SIRPa in human induced pluripotent stem cells (iPSCs) to generate macrophages with superior antitumor functions against solid tumor cancers. We have found through CRISPR/Cas9 genetic engineering that SIRPa-knockout (KO) iPSC-Macrophages (iMacs) have significantly increased antibody-dependent phagocytosis and cytotoxicity against SKOV-3 ovarian cancer, MCF7 breast cancer, and WM266-4 melanoma cancer cell lines than WT iMacs in vitro. Results Furthermore, during an in vitro exhaustion study, SIRPa-KO iMacs that were re-challenged with fresh SKOV-3 + anti-HER2 five times every 24 hours remained active and reduced the overall tumor burden significantly more than WT iMacs. Together, these results support that SIRPa-KO iMacs have superior anti-tumor capacity and significantly enhance the anti-tumor effects of monoclonal antibody (mAb) therapy. Additionally, SIRPa was knocked-out of GD2-CAR-expressing iPSCs to generate SIRPa-KO GD2-CAR iMacs to use against GD2+ solid tumors. Our preliminary in vitro results show increased tumor-killing of WM266-4 GD2+ melanoma by SIRPa-KO GD2-CAR iMacs compared to GD2-CAR iMacs. Using NSG and NCG-X mouse models, luciferase-expressing human solid tumor cell lines are engrafted in the peritoneal cavity or intravenously to recapitulate metastatic growth in the lungs. These xenograft models are currently being assessed for the antitumorigenic properties of SIRPa-KO iMacs and SIRPa-KO GD2-CAR iMacs. Our preliminary results suggest that SIRPa-KO iMacs + anti-HER2 treatment provide the longest survival compared to all other treatment groups, regardless of if they were administered via IV or IP injection. Conclusions In conclusion, we have found that multiplex genetic editing involving knocking-out SIRPa and knocking-in GD2-CAR in human iPSCs produce functional macrophages with superior capacity for antitumorigenic activities against solid tumor cancers and have potential for clinical application.
Authors: Portia R Smith, Jue Zhang, Mark Berres, Ashley Weichmann, Divine M Sedzro, Medha Malik, Igor Slukvin
Language: English
Subfield: Immunology
Field: Immunology and Microbiology
Domain: Life Sciences
Open Access status: hybrid
OpenAlex ID: W4404065345