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Manufacturing Chimeric Antigen Receptor CAR T Cells for Adoptive Immunotherapy
Published on: December 17, 2019
Coexpression of IL15 Promotes Effector Differentiation and Sustained Proliferative Capacity in ALPPL2-Specific Human
David Cunningham1,2, Junquan Liu3, Inci Cevher Zeytin4
1Center for Advanced Innate Cell Therapy, Texas Children's Hospital, Houston, Texas.
Abstract:
Chimeric antigen receptor (CAR) T cells have robust antitumor activity against hematologic malignancies and have the potential to benefit patients with solid tumors. Immune recognition of murine proteins expressed in adoptively transferred T cells and the lack of homeostatic cytokines in the tumor microenvironment can limit the expansion and persistence of CAR T cells. CARs generated only from human sequences could reduce the risk of immune-mediated rejection, and interleukin 15 (IL15), which promotes T-cell survival and fitness, may improve the expansion and persistence of CAR T cells. In this study, we report a CAR construct (ABBz) assembled from human sequences including a single-chain variable fragment (scFv) specific to alkaline phosphatase, placental-like 2 (ALPPL2). This binder was selected through an unbiased, high-throughput screen of a human antibody-derived, phage-displayed scFv library based on binding specificity, stringency, and low dissociation constant. We demonstrated specificity to the antigen, effective cytolytic function, and cytokine production in ABBz T cells. We showed NK-like effector differentiation with sustained proliferative capacity specific to secreted IL15 coexpression in ABBz T cells. Lastly, we demonstrated that ABBz CAR T cells had robust antitumor activity, which was further enhanced through IL15 coexpression, resulting in NK-like effector differentiation with increased cytotoxicity and superior expansion capacity due to reduced apoptosis of CAR T cells. These results demonstrate that IL15 coexpression can promote effector differentiation while maintaining the proliferative capacity of huALPPL2-CAR T cells and provide a foundation for further clinical development of IL15-coexpressing huALPPL2-CAR T cells in patients.
Insights
Human-derived chimeric antigen receptor (CAR) T cells targeting ALPPL2 show enhanced antitumor activity. Co-expression of interleukin-15 (IL15) improves CAR T-cell expansion and persistence, offering potential for solid tumor treatment.
Area of Science:
- Immunology
- Oncology
- Biotechnology
Background:
- Chimeric antigen receptor (CAR) T cells demonstrate efficacy in hematologic cancers but face challenges in solid tumors, including immune rejection and limited persistence.
- Murine protein recognition and the tumor microenvironment's lack of homeostatic cytokines hinder CAR T-cell expansion and survival.
- Utilizing fully human CAR sequences and incorporating cytokines like interleukin-15 (IL15) can potentially overcome these limitations.
Purpose of the Study:
- To develop and evaluate a fully human CAR T-cell construct targeting the antigen ALPPL2 for solid tumor therapy.
- To investigate the impact of co-expressing IL15 on the expansion, persistence, and effector function of human ALPPL2-specific CAR T cells.
Main Methods:
- A human antibody-derived phage-displayed scFv library was screened to identify a binder specific to ALPPL2, forming the basis of the ABBz CAR construct.
- ABBz CAR T cells were engineered with or without co-expressed IL15.
- Antigen specificity, cytolytic function, cytokine production, NK-like effector differentiation, proliferative capacity, and antitumor activity in vitro and in vivo were assessed.
Main Results:
- The ABBz CAR construct, derived from human sequences, demonstrated antigen specificity and effective cytotoxic function.
- Co-expression of IL15 induced NK-like effector differentiation in ABBz CAR T cells, enhancing proliferative capacity and reducing apoptosis.
- ABBz CAR T cells exhibited robust antitumor activity, which was significantly augmented by IL15 co-expression, leading to improved cytotoxicity and expansion.
Conclusions:
- Co-expression of IL15 promotes effector differentiation and enhances the proliferative capacity of human ALPPL2-CAR T cells.
- The developed huALPPL2-CAR T cells, particularly with IL15 co-expression, show promising antitumor activity and potential for clinical development in solid tumors.
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