Engineering CD19-specific T lymphocytes with interleukin-15 and a suicide gene to enhance their anti-lymphoma/leukemia effects and safety

Abstract

T lymphocytes expressing a chimeric antigen receptor (CAR) targeting the CD19 antigen (CAR.19) may be of value for the therapy of B-cell malignancies. Because the in vivo survival, expansion and anti-lymphoma activity of CAR.19+ T cells remain suboptimal even when the CAR contains a CD28 costimulatory endodomain, we generated a novel construct that also incorporates the interleukin-15 (IL15) gene and an inducible caspase-9-based suicide gene (iC9/CAR.19/IL15). We found that compared to CAR.19+ T cells, iC9/CAR.19/IL15+ T cells had: (i) greater numeric expansion upon antigen stimulation (10-fold greater expansion in vitro, and 3 to 15 fold greater expansion in vivo) and reduced cell death rate (Annexin-V+/7-AAD+ cells 10% ± 6% for iC9/CAR.19/IL15+ T cells and 32% ± 19% CAR.19+ T cells); (ii) reduced expression of the programmed death 1 (PD-1) receptor upon antigen stimulation (PD-1+ cells <15% for iC9/CAR.19/IL15+ T cells versus >40% for CAR.19+ T cells); (iii) improved anti-tumor effects in vivo (from 4.7 to 5.4-fold reduced tumor growth). In addition, iC9/CAR.19/IL15+ T cells were efficiently eliminated upon pharmacologic activation of the suicide gene. In summary, this strategy safely increases the anti-lymphoma/leukemia effects of CAR.19-redirected T lymphocytes and may be a useful approach for treatment of patients with B-cell malignancies.

Improving Chimeric Antigen Receptor-Modified T Cell Function by Reversing the Immunosuppressive Tumor Microenvironment of Pancreatic Cancer

“…36 Additionally, CAR T cells themselves have been modified by the incorporation of co-stimulatory endodomains such as CD28, 4-1BB, and OX40, 37,38 though our results suggest that this is likely insufficient to provide long term in vivo benefit at the tumor site ( Figure S1). Other modifications include the transgenic expression of Th1 cytokines to promote autocrine growth 36,[39][40][41] or the incorporation of a dominant-negative TGF-b receptor, which sequesters this tumor-produced immunosuppressive cytokine. 42,43 Our approach extends upon the dominant-negative receptor concept by inverting a soluble immunosuppressive signal present in the tumor microenvironment into one that is immunostimulatory (4/7 ICR).…”

Augmentation of Hepatitis B Virus-Specific Cellular Immunity with Programmed Death Receptor-1/Programmed Death Receptor-L1 Blockade in Hepatitis B Virus and HIV/Hepatitis B Virus Coinfected Patients Treated with Adefovir

“…PD-1 blockade is a therapeutic strategy currently being developed for the treatment for malignancies and other chronic immune disorders. 37,39 Our data provide compelling evidence that PD-1 blockade should be investigated in vivo as a viable, adjunct treatment for CHB infection in HIVpositive and potentially HIV-negative patients, especially if the combined effect can eradicate HBV.…”

T-cell and natural killer cell therapies for hematologic malignancies after hematopoietic stem cell transplantation: enhancing the graft-versus-leukemia effect

“…62 Additionally, to further improve the efficacy of CAR-modified T cells some groups are exploring the incorporation of two or more co-stimulatory domains (socalled third-generation CAR) 62,63 or combining them with other antibody recognition domains (so-called tandem CAR). 64 Addition of cytokine signals such as IL-21 65 and IL-15 66 has also been explored. Other attempts to improve in vivo persistence involve utilizing the endogenous signaling provided by latent viruses 67,68 which have been explored clinically in neuroblastoma and B-cell leukemias/lymphomas.…”