Lifespan‐Regulated CAR‐Macrophages from Myeloid Progenitors for Enhanced Colorectal Cancer Therapy

Using a tamoxifen‐inducible Hoxb8 system, proliferative bone marrow progenitors can be generated, which are subsequently engineered with an anti‐CEA CAR construct containing a suicide gene (iCas9) and differentiated into CAR‐macrophages. This method facilitates scale up the production of CAR‐macrophages. Meanwhile, lifespan‐regulated CAR‐macrophages from myeloid progenitors enhance solid tumor immunotherapy, overcoming gene transduction efficiency and scalability for advanced cancer therapy. Abstract Adoptive cell therapies for solid tumors face persistent challenges from poor tumor infiltration and immunosuppressive microenvironment. To overcome these limitations, a clinically scalable platform is developed to generate chimeric antigen receptor macrophages (CAR‐HMs) from tamoxifen‐regulated immortalized Hoxb8‐transduced myeloid progenitors, achieving >95% CAR transduction efficiency and 60‐fold expansion within 10 days. Engineered with a colorectal cancer‐specific anti‐carcinoembryonic antigen (CEA) CAR, these FcγRI‐CAR‐HMs demonstrated potent tumoricidal activity (>80% CRC cell lysis in vitro), deep tissue penetration (>100 µm in 3D tumor spheroids), and significant therapeutic efficacy (≈89% tumor regression in vivo). Mechanistic studies demonstrated that FcγRI‐CAR‐HMs remodeled the tumor microenvironment through direct tumor phagocytosis, T cells recruitment and activation, and synergistic enhancement of anti‐PD‐1 therapy in colorectal cancer models, while an integrated inducible caspase‐9 (iCas9) suicide switch ensured safety without compromising long‐term persistence. This progenitors‐based platform not only addresses critical manufacturing challenges but also unlocks the full therapeutic potential of CAR‐macrophages, whose unique ability to synergize with checkpoint inhibitors provides a transformative approach for treatment‐refractory solid tumors. Using a tamoxifen-inducible Hoxb8 system, proliferative bone marrow progenitors can be generated, which are subsequently engineered with an anti-CEA CAR construct containing a suicide gene (iCas9) and differentiated into CAR-macrophages. This method facilitates scale up the production of CAR-macrophages. Meanwhile, lifespan-regulated CAR-macrophages from myeloid progenitors enhance solid tumor immunotherapy, overcoming gene transduction efficiency and scalability for advanced cancer therapy. Abstract Adoptive cell therapies for solid tumors face persistent challenges from poor tumor infiltration and immunosuppressive microenvironment. To overcome these limitations, a clinically scalable platform is developed to generate chimeric antigen receptor macrophages (CAR-HMs) from tamoxifen-regulated immortalized Hoxb8-transduced myeloid progenitors, achieving >95% CAR transduction efficiency and 60-fold expansion within 10 days. Engineered with a colorectal cancer-specific anti-carcinoembryonic antigen (CEA) CAR, these FcγRI-CAR-HMs demonstrated potent tumoricidal activity (>80% CRC cell lysis in vitro), deep tissue penetration (>100 µm in 3D tumor spheroids), and significant therapeutic efficacy (≈89% tumor regression in vivo). Mechanistic studies demonstrated that FcγRI-CAR-HMs remodeled the tumor microenvironment through direct tumor phagocytosis, T cells recruitment and activation, and synergistic enhancement of anti-PD-1 therapy in colorectal cancer models, while an integrated inducible caspase-9 (iCas9) suicide switch ensured safety without compromising long-term persistence. This progenitors-based platform not only addresses critical manufacturing challenges but also unlocks the full therapeutic potential of CAR-macrophages, whose unique ability to synergize with checkpoint inhibitors provides a transformative approach for treatment-refractory solid tumors. Advanced Science, Volume 12, Issue 43, November 20, 2025.