Tumor-Specific Reactive Oxygen Species Accelerators Improve Chimeric Antigen Receptor T Cell Therapy in B Cell Malignancies.

Hyeon Joo Yoo,Carsten Müller-Tidow,Andriy Mokhir,Angela Hückelhoven-Krauss,Brigitte Neuber,Ulrike Gern,Anita Schmitt,Maria-Luisa Schubert,Michael Schmitt,Lei Wang,Peter Dreger,Sanmei Wang,Yibin Liu,Jean-Marc Hoffmann,Leopold Sellner

doi:10.3390/ijms20102469

Abstract

Chimeric antigen receptor T cell (CART) therapy is currently one of the most promising treatment approaches in cancer immunotherapy. However, the immunosuppressive nature of the tumor microenvironment, in particular increased reactive oxygen species (ROS) levels, provides considerable limitations. In this study, we aimed to exploit increased ROS levels in the tumor microenvironment with prodrugs of ROS accelerators, which are specifically activated in cancer cells. Upon activation, ROS accelerators induce further generation of ROS. This leads to an accumulation of ROS in tumor cells. We hypothesized that the latter cells will be more susceptible to CARTs. CD19-specific CARTs were generated with a CD19.CAR.CD28.CD137zeta third-generation retroviral vector. Cytotoxicity was determined by chromium-51 release assay. Influence of the ROS accelerators on viability and phenotype of CARTs was determined by flow cytometry. The combination of CARTs with the ROS accelerator PipFcB significantly increased their cytotoxicity in the Burkitt lymphoma cell lines Raji and Daudi, as well as primary chronic lymphocytic leukemia cells. Exposure of CARTs to PipFcB for 48 h did not influence T cell exhaustion, viability, or T cell subpopulations. In summary, the combination of CARTs with ROS accelerators may improve adoptive immunotherapy and help to overcome tumor microenvironment-mediated treatment resistance.

Highlights

CD19-specific chimeric antigen receptor T cell (CART) therapy is currently one of the most outstanding cellular immunotherapy approaches, achieving substantial clinical benefit for patients with relapsed B-cell malignancies [1]
Highest levels of lysis of the tested time points was achieved after 12 h incubation, at an effector:target (E:T) ratio of 20:1 and 10 μM PipFcB (PipFcB 10 μM vs. dimethyl sulfoxide (DMSO): Daudi 75% ± 2% vs. 39% ± 1%, p < 0.001, Raji 92% ± 1% vs. 25% ± 1%, p < 0.001)
To therapeutically exploit immunosuppressive influences of the tumor-microenvironment, we evaluated synergistic influences and functional effects of reactive oxygen species (ROS) accelerators in combination with CD19-specific CARTs

Summary

Introduction

CD19-specific chimeric antigen receptor T cell (CART) therapy is currently one of the most outstanding cellular immunotherapy approaches, achieving substantial clinical benefit for patients with relapsed B-cell malignancies [1]. Enhancing efficacy of CART therapy using combination strategies may be necessary to overcome resistance and achieve long-lasting remissions. Cancer therapy against only a single target may facilitate the development of resistances. The combination with targeted drugs or immunomodulatory compounds may be a promising approach to improve clinical efficacy of CARTs. Previous studies reported that the addition of ibrutinib or lenalidomide to CART cells can improve effector functions in vitro, as well as tumor control in vivo [5,6,7]. CART combination therapy approaches are a major focus of research efforts and may overcome treatment resistance towards adoptive immunotherapy

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