Targeting the Tumor Microenvironment with Gene-Engineered Immune Cells: Focus on CAR-Macrophages and CAR-NK Cells – A Review Article

Farzand Farhad  Hamid

doi:10.64048/hir.v1n3.007

Authors

Farzand Farhad Hamid General Directorate of Research Center, University of Salahaddin – Erbil, Kerkuk Street, Erbil, 44001, Iraq Author https://orcid.org/0009-0008-3884-4109

DOI:

https://doi.org/10.64048/hir.v1n3.007

Keywords:

Tumor microenvironment, CAR macrophages, CAR-NK cells, Cancer immunotherapy, Gene-engineered immune cells, Solid tumors, Innate immune therapy

Abstract

The TME is a culprit of immunosuppression and a significant hurdle to long-term immunotherapeutic success in solid tumors, which are often associated with a dense stroma, hypoxia, and immunosuppressive myeloid and lymphoid cells. Conventional CAR-T cells tend to fail in this scenario as they are subjected to restricted trafficking, functional exhaustion, and inhibitory cues. Innate immune effectors including macrophages and natural killer (NK) cells are natural resident solid tumor infiltrates with strong cytotoxic and phagocytic potential, and thus represent promising chassis for CAR engineering. CARmacrophages (CAR-M) CAR-Ms can phagocytose tumor cells directly and modulate the TME towards inflammation and superior T cell priming, whereas CAR-NK cells have the advantage of combining antigen-specific targeting with innate recognition, ADCC, and outstanding safety profile. Here, we review recent preclinical and clinical progress in CAR-M and CAR-NK therapy, focusing on their potential to modulate the TME, discuss engineering approaches to resist TME-imposed challenges, and present new clinical trials. We conclude that CAR-M and CAR-NK platforms represent complementary strategies to turning “cold” tumors “hot”, but that enhanced persistence, trafficking, and on-target, off-tumor safety are needed.

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References

ABDOU, Y., MORTIMER, J., POHLMANN, P., JOHNSON, M., MAZIARZ, R., SPECHT, J. M., DEES, C., UENO, N., YUAN, Y. & ANGELOS, M. Translational insights from a phase 1, first-in-human (FIH) clinical trial of the anti-HER2 CAR macrophage CT-0508 in participants with HER2 positive metastatic breast cancer and other HER2 overexpressing solid tumors. Cancer Research, 2024. AMER ASSOC CANCER RESEARCH 615 CHESTNUT ST, 17TH FLOOR, PHILADELPHIA, PA. https://doi.org/10.1158/1538-7445.SABCS23-PO2-04-08.

AMOOZGAR, B., BANGOLO, A., MANSOUR, C., ELIAS, D., MOHAMED, A., THOR, D. C., EHSANULLAH, S. U., TRAN, H. H.-V., AGUILAR, I. K. & WEISSMAN, S. 2025. Engineering Innate Immunity: Recent Advances and Future Directions for CAR-NK and CAR–Macrophage Therapies in Solid Tumors. Cancers, 17, 2397. https://doi.org/10.3390/cancers17142397.

BALKHI, S., ZUCCOLOTTO, G., DI SPIRITO, A., ROSATO, A. & MORTARA, L. 2025. CAR-NK cell therapy: promise and challenges in solid tumors. Front Immunol, 16, 1574742. https://doi.org/10.3389/fimmu.2025.1574742.

BALTA, E., WABNITZ, G. H. & SAMSTAG, Y. 2021. Hijacked Immune Cells in the Tumor Microenvironment: Molecular Mechanisms of Immunosuppression and Cues to Improve T Cell-Based Immunotherapy of Solid Tumors. International Journal of Molecular Sciences, 22, 5736. https://doi.org/10.3390/ijms22115736.

BURGER, M. C., FORSTER, M. T., ROMANSKI, A., STRAßHEIMER, F., MACAS, J., ZEINER, P. S., STEIDL, E., HERKT, S., WEBER, K. J., SCHUPP, J., LUN, J. H., STRECKER, M. I., WLOTZKA, K., CAKMAK, P., OPITZ, C., GEORGE, R., MILDENBERGER, I. C., NOWAKOWSKA, P., ZHANG, C., RÖDER, J., MÜLLER, E., IHRIG, K., LANGEN, K. J., RIEGER, M. A., HERRMANN, E., BONIG, H., HARTER, P. N., REISS, Y., HATTINGEN, E., RÖDEL, F., PLATE, K. H., TONN, T., SENFT, C., STEINBACH, J. P. & WELS, W. S. 2023. Intracranial injection of natural killer cells engineered with a HER2-targeted chimeric antigen receptor in patients with recurrent glioblastoma. Neuro Oncol, 25, 2058-2071. https://doi.org/10.1093/neuonc/noad087.

CHETTRI, D., SATAPATHY, B. P., YADAV, R., UTTAM, V., JAIN, A. & PRAKASH, H. 2025. CAR-macrophages: tailoring cancer immunotherapy. Frontiers in Immunology, Volume 15 – 2024. https://doi.org/10.3389/fimmu.2024.1532833.

DE VISSER, K. E. & JOYCE, J. A. 2023. The evolving tumor microenvironment: From cancer initiation to metastatic outgrowth. Cancer Cell, 41, 374-403. https://doi.org/10.1016/j.ccell.2023.02.016.

DOEPPNER, C. A., BINDER, A. K., BREMM, F., FEUCHTER, N., DÖRRIE, J. & SCHAFT, N. 2025. Rendering NK Cells Antigen-Specific for the Therapy of Solid Tumours. International Journal of Molecular Sciences, 26, 6290. https://doi.org/10.3390/ijms26136290.

GALVEZ-CANCINO, F., ARMERO, M., WITHERS, D. R., MOLERO-GLEZ, P., MELERO, A., PALENCIA, B. & MELERO, I. 2025. The Dark Side of NK Cells in Cancer Immunotherapy. Cancer Discovery, 15, 1777-1779. https://doi.org/10.1158/2159-8290.CD-25-1042.

GAO, C., HONG, F., DONG, Y., FU, Y., MA, Y., SUN, X., ZHANG, J., CHEN, J. & HUANG, Z. 2025. Lifespan‐Regulated CAR‐Macrophages from Myeloid Progenitors for Enhanced Colorectal Cancer Therapy. Advanced Science, 12, e17677. https://doi.org/10.1002/advs.202417677.

HE, S., ZHENG, L. & QI, C. 2025. Myeloid-derived suppressor cells (MDSCs) in the tumor microenvironment and their targeting in cancer therapy. Molecular Cancer, 24, 5. https://doi.org/10.1186/s12943-024-02208-3.

HUANG, T., BEI, C., HU, Z. & LI, Y. 2024. CAR-macrophage: Breaking new ground in cellular immunotherapy. Frontiers in Cell and Developmental Biology, Volume 12 – 2024. https://doi.org/10.3389/fcell.2024.1464218.

JING, J., CHEN, Y., CHI, E., LI, S., HE, Y., WANG, B., SHEN, H., FAN, L., WANG, J., SHANGGUAN, T., GE, X., JIANG, Y., CHEN, Y. & XU, C. 2025. New power in cancer immunotherapy: the rise of chimeric antigen receptor macrophage (CAR-M). Journal of Translational Medicine, 23, 1182. https://doi.org/10.1186/s12967-025-07115-9.

KAISER, Y., GARRIS, C. S., MARINARI, E., KIM, H. S., OH, J., PEDARD, M., HALABI, E. A., CHOI, M., PARVANIAN, S., KOHLER, R., MIGLIORINI, D. & WEISSLEDER, R. 2025. Targeting immunosuppressive myeloid cells via implant-mediated slow release of small molecules to prevent glioblastoma recurrence. Nature Biomedical Engineering. https://doi.org/10.1038/s41551-025-01533-2.

KOPPERS, M. J. A., MONNIKHOF, M., MEELDIJK, J., KOORMAN, T. & BOVENSCHEN, N. 2025. Chimeric antigen receptor-macrophages: Emerging next-generation cell therapy for brain cancer. Neuro-Oncology Advances, 7. https://doi.org/10.1093/noajnl/vdaf059.

KUMAR SINGH, V., AWASTHI, S. & SHARMA, S. 2025. Natural killer cell-based Immunotherapy for Solid tumors: A Comprehensive Review Iran J Blood Cancer. 2025 June 30; 17 (2): 83-98. Iran J Blood Cancer, 17, 83-98. http://dx.doi.org/doi:0000-0002-7556-2505.

KUZNETSOVA, A. V., GLUKHOVA, X. A., BELETSKY, I. P. & IVANOV, A. A. 2025. NK cell activity in the tumor microenvironment. Frontiers in Cell and Developmental Biology, Volume 13 – 2025. https://doi.org/10.3389/fcell.2025.1609479.

LI, X., WANG, X., WANG, H., ZUO, D., XU, J., FENG, Y., XUE, D., ZHANG, L., LIN, L. & ZHANG, J. 2024. A clinical study of autologous chimeric antigen receptor macrophage targeting mesothelin shows safety in ovarian cancer therapy. Journal of Hematology & Oncology, 17, 116. https://doi.org/10.1186/s13045-024-01635-5.

LI, Y., GAO, Y., WANG, L. & SI, J. 2025. NK cell adaptation in the tumor microenvironment: Insights for NK cell-based immunotherapy. Cytokine & Growth Factor Reviews, 86, 181-198. https://doi.org/10.1016/j.cytogfr.2025.10.003.

LOOK, T., SANKOWSKI, R., BOUZEREAU, M., FAZIO, S., SUN, M., BUCK, A., BINDER, N., MASTALL, M., PRISCO, F., SEEHUSEN, F., FREI, J., WYSS, C., SNIJDER, B., NOMBELA ARRIETA, C., WELLER, M., PASCOLO, S. & WEISS, T. 2025. CAR T cells, CAR NK cells, and CAR macrophages exhibit distinct traits in glioma models but are similarly enhanced when combined with cytokines. Cell Reports Medicine, 6. https://doi.org/10.1016/j.xcrm.2025.101931.

LU, J., MA, Y., LI, Q., XU, Y., XUE, Y. & XU, S. 2024. CAR Macrophages: a promising novel immunotherapy for solid tumors and beyond. Biomarker Research, 12, 86. https://doi.org/10.1186/s40364-024-00637-2.

LV, R., GUO, Y., LIU, W., DONG, G., LIU, X., LI, C., REN, Y., ZHANG, Z., NEO, S.-Y. & MAO, W. 2024. Revolutionizing cancer treatment: the emerging potential and potential challenges of in vivo self-processed CAR cell therapy. Theranostics, 14, 7424. https://doi.org/10.7150/thno.101941.

MA, R., LI, Z., CHIOCCA, E. A., CALIGIURI, M. A. & YU, J. 2023. The emerging field of oncolytic virus-based cancer immunotherapy. Trends Cancer, 9, 122-139. https://doi.org/10.1016/j.trecan.2022.10.003.

MAALEJ, K. M., MERHI, M., INCHAKALODY, V. P., MESTIRI, S., ALAM, M., MACCALLI, C., CHERIF, H., UDDIN, S., STEINHOFF, M., MARINCOLA, F. M. & DERMIME, S. 2023. CAR-cell therapy in the era of solid tumor treatment: current challenges and emerging therapeutic advances. Molecular Cancer, 22, 20. https://doi.org/10.1186/s12943-023-01723-z.

MORVA, A., ARROYO, A. B., ANDREEVA, L., TAPIA-ABELLÁN, A. & LUENGO-GIL, G. 2025. Unleashing the power of CAR-M therapy in solid tumors: a comprehensive review. Frontiers in Immunology, Volume 16 – 2025. https://doi.org/10.3389/fimmu.2025.1615760.

NING, P., DU, F., WANG, H., GONG, X., XIA, Y., ZHANG, X., DENG, H., ZHANG, R. & WANG, Z. 2024. Genetically engineered macrophages as living cell drug carriers for targeted cancer therapy. Journal of Controlled Release, 367, 697-707. https://doi.org/10.1016/j.jconrel.2024.02.003.

PENG, L., SFERRUZZA, G., YANG, L., ZHOU, L. & CHEN, S. 2024. CAR-T and CAR-NK as cellular cancer immunotherapy for solid tumors. Cellular & Molecular Immunology, 21, 1089-1108. https://doi.org/10.1038/s41423-024-01207-0.

PENG, M., ZHU, Y., HU, Y., WEN, J. & HUANG, W. 2025. Advances in the regulation of macrophage polarization by the tumor microenvironment. Discover Oncology, 16, 1487. https://doi.org/10.1007/s12672-025-03258-9.

PIERINI, S., GABBASOV, R., OLIVEIRA-NUNES, M. C., QURESHI, R., WORTH, A., HUANG, S., NAGAR, K., GRIFFIN, C., LIAN, L., YASHIRO-OHTANI, Y., ROSS, K., SLOAS, C., BALL, M., SCHOTT, B., SONAWANE, P., CORNELL, L., BLUMENTHAL, D., CHHUM, S., MINUTOLO, N., CICCAGLIONE, K., SHAW, L., ZENTNER, I., LEVITSKY, H., SHESTOVA, O., GILL, S., VARGHESE, B., CUSHING, D., CEERAZ DELONG, S., ABRAMSON, S., CONDAMINE, T. & KLICHINSKY, M. 2025. Chimeric antigen receptor macrophages (CAR-M) sensitize HER2+ solid tumors to PD1 blockade in pre-clinical models. Nature Communications, 16, 706. https://doi.org/10.1038/s41467-025-57496-0.

REISS, K., YUAN, Y., UENO, N., JOHNSON, M., CLAIRE DEES, E., ANGELOS, M., CHAO, J., GILL, S., SHESTOVA, O., SERODY, J., PRICEMAN, S., RONCZKA, A., QURESHI, R., SONAWANE, P., CUSHING, D., BARTON, D., KLICHINSKY, M., CONDAMINE, T., SWABY, R. & ABDOU, Y. 2022. 634 A phase 1, first-in-human (FIH) clinical trial of the anti-HER2 CAR macrophage CT-0508 in participants with HER2 overexpressing solid tumors. Journal for Immunotherapy of Cancer, 10. https://doi.org/10.1136/jitc-2022-SITC2022.0634.

REISS, K. A., ANGELOS, M. G., DEES, E. C., YUAN, Y., UENO, N. T., POHLMANN, P. R., JOHNSON, M. L., CHAO, J., SHESTOVA, O. & SERODY, J. S. 2025a. CAR-macrophage therapy for HER2-overexpressing advanced solid tumors: a phase 1 trial. Nature medicine, 1-12. https://doi.org/10.1038/s41591-025-03495-z.

REISS, K. A., ANGELOS, M. G., DEES, E. C., YUAN, Y., UENO, N. T., POHLMANN, P. R., JOHNSON, M. L., CHAO, J., SHESTOVA, O., SERODY, J. S., SCHMIERER, M., KREMP, M., BALL, M., QURESHI, R., SCHOTT, B. H., SONAWANE, P., DELONG, S. C., CHRISTIANO, M., SWABY, R. F., ABRAMSON, S., LOCKE, K., BARTON, D., KENNEDY, E., GILL, S., CUSHING, D., KLICHINSKY, M., CONDAMINE, T. & ABDOU, Y. 2025b. CAR-macrophage therapy for HER2-overexpressing advanced solid tumors: a phase 1 trial. Nat Med, 31, 1171-1182. https://doi.org/10.1038/s41591-025-03495-z.

SARHAN, D., EISINGER, S., HE, F., BERGSLAND, M., PELICANO, C., DRIESCHER, C., WESTBERG, K., BENITEZ, I. I., HAMOUD, R., PALANO, G., LI, S., CARANNANTE, V., MUHR, J., ÖNFELT, B., SCHLISIO, S., RAVETCH, J. V., HEUCHEL, R., LÖHR, M. J. & KARLSSON, M. C. I. 2022. Targeting myeloid suppressive cells revives cytotoxic anti-tumor responses in pancreatic cancer. iScience, 25. https://doi.org/10.2139/ssrn.4047254.

WANG, S., YANG, Y., MA, P., ZHA, Y., ZHANG, J., LEI, A. & LI, N. 2022. CAR-macrophage: An extensive immune enhancer to fight cancer. EBioMedicine, 76, 103873 https://doi.org/10.1016/j.ebiom.2022.103873.

YU, J., KONG, X. & FENG, Y. 2025. Tumor microenvironment-driven resistance to immunotherapy in non-small cell lung cancer: strategies for Cold-to-Hot tumor transformation. Cancer Drug Resist, 8, 21. https://doi.org/10.20517/cdr.2025.14.

YU, Y. & HO, M. 2025. CAR NK cell therapy for solid tumors: potential and challenges. Antibody Therapeutics, 8, 275-289. https://doi.org/10.1093/abt/tbaf019.