Th185 - Tackling the HIV Reservoir with Hiv-resistant anti-pd-1 CAR-T Cells

Riddhima Banga – Service of Immunology and Allergy, Department of Medicine, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland; Nicole Kadzioch – Department of Infectious Diseases and Hospital Epidemiology, University Hospital of Zurich, University of Zurich, Zurich, Switzerland; Ana Alcaraz-Serna – Service of Immunology and Allergy, Department of Medicine, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland; Oscar Alfageme-Abello – Service of Immunology and Allergy, Department of Medicine, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland; Raphael Porret – Service of Immunology and Allergy, Department of Medicine, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland; Erica Lana – Service of Immunology and Allergy, Department of Medicine, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland; Matthieu Perreau – Service of Immunology and Allergy, Department of Medicine, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland; Craig Fenwick – Service of Immunology and Allergy, Department of Medicine, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland; Simon Bredl – Department of Infectious Diseases and Hospital Epidemiology, University Hospital of Zurich, University of Zurich, Zurich, Switzerland; Roberto Speck – Department of Infectious Diseases and Hospital Epidemiology, University Hospital of Zurich, University of Zurich, Zurich, Switzerland; Giuseppe Pantaleo – Service of Immunology and Allergy, Department of Medicine, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland; Yannick Muller – Service of Immunology and Allergy, Department of Medicine, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland

Abstract Text:

Background: A successful strategy to cure HIV would require eradicating its reservoir, mainly represented by PD-1+ T follicular helper cells. Herein, we hypothesize that chimeric antigen receptor (CAR)-T cells redirected against PD-1 may represent an effective approach to target the HIV reservoir.

Methods: Second-generation CARs were cloned using the scFv of a blocking (bPD1-CAR) and a nonblocking (nbPD1-CAR) anti-PD-1 monoclonal antibody fused to an IgG4 hinge, CD28 transmembrane and 4-1BB signaling domains with a cherry reporter. Anti-CD19 CAR-T cells were used as controls. The killing activity was measured using luciferase-based assays and a real-time quantitative live-cell imaging platform. HIV resistance against R5 and X4 HIV strains was tested by selectively editing the CD4 receptor and/or CCR5 and CXCR4 co-receptors in different combinations using CRISPR-Cas9 technologies.

Results: The PD-1 binding affinity and KD values of the two anti-PD-1 mAbs were similar. Both anti-PD-1, but not CD19-control, CAR-T cells caused delayed depletion of PD-1+ CD4+ cherry negative T cells in ex-vivo cultures. Interestingly, the bPD1-CAR but not the nbPD1-CAR mediated tonic signaling, which was efficiently prevented by editing the endogenous PD-1. Both anti-PD-1 CAR-T cells equivalently killed PD-1high transgenic cells, yet the nbPD1-CAR was significantly less efficient in killing wild-type PD-1low target cells. CD4 editing was sufficient to confer HIV-resistance against R5 and X4 HIV strains without impairing the killing activity.

Conclusion: We successfully engineered two anti-PD-1 CARs with different functional activities. In-vivo experiments in humanized HIV-infected mice are undergoing.