OR05
A universal platform to generate chimeric antigen receptor macrophages from human stem cell sources
D Paasch¹ ² S M Abdin³ ⁴ J Meyer¹ C Kloth¹ ² M Ackermann¹ ³ ⁴ C S von Kaisenberg⁵ J Kuehle⁶ A Holzinger⁷ H Abken⁷ A Schambach¹ ³ ⁸ N Lachmann¹ ³ ⁴ M Morgan¹ ³ T Moritz¹ ²
1:Institute of Experimental Hematology, Hannover Medical School, 30625 Hannover, Germany; 2:Research Group Reprogramming and Gene Therapy, Hannover Medical School, 30625 Hannover, Germany; 3:REBIRTH Research Center for Translational and Regenerative Medicine, 30625 Hannover, Germany; 4:Clinic for Pediatric Pneumology, Allergology and Neonatology, Hannover Medical School, 30625 Hannover, Germany; 5:Department of Obstetrics and Gynecology, Hannover Medical School, 30625 Hannover, Germany; 6:Center for Molecular Medicine Cologne, University of Cologne, 50931 Cologne, Germany; 7:Leibniz Institute for Immunotherapy, Div. Genetic Immunotherapy, and University Regensburg, 93053 Regensburg, Germany; 8:Division of Hematology/Oncology, Children's Hospital Boston, Harvard Medical School, Boston, MA, USA
Whereas immunotherapy using chimeric antigen receptor (CAR) technology has shown great efficacy to enhance T cell cytotoxicity in hematologic malignancies, the treatment of solid tumors remains challenging. In this context, CAR-macrophages (CAR-Macs) recently have been introduced as an additional tool. We here demonstrate the feasibility to use human hematopoietic stem and progenitor cells (HSPCs) as a source to generate functional CAR-Macs that target carcinoembryonic antigen (CEA, CD66e) expressed on pancreatic, colorectal and other tumors (αCEA-CAR-Macs). Additionally, we employ induced pluripotent stem cells (iPSCs) to generate CAR-Macs targeting the CD19 antigen (αCD19-CAR-iMacs) that allows for the sustained production of CAR-Mac effector cells in up-scalable quantities. αCEA-CAR-Macs and αCD19-CAR-iMacs both showed stable CAR expression and demonstrated morphology, phenotype (CD45⁺, CD11b⁺, CD14⁺, CD163⁺) and basic functionality similar to unmodified macrophages. Two αCEA-CAR-Mac constructs that differ in their CAR signal transduction domain (DAP12 or CD3ζ) were investigated. Both CAR macrophage configurations showed antigen specificity and displayed high pro-inflammatory cytokine secretion upon contact to CEA-positive target cells. Furthermore, CD3ζ-expressing αCEA-CAR-Macs showed increased phagocytosis of CEA-positive target cells compared to CEA-negative control cells. We furthermore generated αCD19-CAR-iMacs from iPSC-based continuous differentiation platform, previously developed by our group, without the loss of CAR expression or activity. Furthermore, co-culture systems revealed that αCD19-CAR-iMacs were capable of targeting CD19-positive target cells, shown by increased phagocytosis and pro-inflammatory cytokine secretion. In summary, we provide a universal tool for generating highly-functional HSPC- or iPSC-derived CAR-Macs, thus, paving the way for future CAR-Mac-based immunotherapy strategies.