Metabolic radiolabeling and in vivo PET imaging of cytotoxic T lymphocytes to guide combination adoptive cell transfer cancer therapy

Zhi Yang,Kui Li,Feng Wang,Yanpu Wang,Hua Zhu,Ting Zhang,Dehua Lu,Shixin Zhou,Zhaofei Liu

doi:10.1186/s12951-021-00924-2

Abstract

BackgroundAdoptive T cell transfer-based immunotherapy yields unsatisfactory results in the treatment of solid tumors, partially owing to limited tumor infiltration and the immunosuppressive microenvironment in solid tumors. Therefore, strategies for the noninvasive tracking of adoptive T cells are critical for monitoring tumor infiltration and for guiding the development of novel combination therapies.MethodsWe developed a radiolabeling method for cytotoxic T lymphocytes (CTLs) that comprises metabolically labeling the cell surface glycans with azidosugars and then covalently conjugating them with 64Cu-1,4,7-triazacyclononanetriacetic acid-dibenzo-cyclooctyne (64Cu-NOTA-DBCO) using bioorthogonal chemistry. 64Cu-labeled control-CTLs and ovalbumin-specific CTLs (OVA-CTLs) were tracked using positron emission tomography (PET) in B16-OVA tumor-bearing mice. We also investigated the effects of focal adhesion kinase (FAK) inhibition on the antitumor efficacy of OVA-CTLs using a poly(lactic-co-glycolic) acid (PLGA)-encapsulated nanodrug (PLGA-FAKi).ResultsCTLs can be stably radiolabeled with 64Cu with a minimal effect on cell viability. PET imaging of 64Cu-OVA-CTLs enables noninvasive mapping of their in vivo behavior. Moreover, 64Cu-OVA-CTLs PET imaging revealed that PLGA-FAKi induced a significant increase in OVA-CTL infiltration into tumors, suggesting the potential for a combined therapy comprising OVA-CTLs and PLGA-FAKi. Further combination therapy studies confirmed that the PLGA-FAKi nanodrug markedly improved the antitumor effects of adoptive OVA-CTLs transfer by multiple mechanisms.ConclusionThese findings demonstrated that metabolic radiolabeling followed by PET imaging can be used to sensitively profile the early-stage migration and tumor-targeting efficiency of adoptive T cells in vivo. This strategy presents opportunities for predicting the efficacy of cell-based adoptive therapies and for guiding combination regimens.Graphic

Highlights

Cell-based therapies, such as the adoptive cell transfer of engineered T cells and natural killer cells, represent promising strategies in cancer immunotherapy
Because Focal adhesion kinase (FAK) inhibition potentially promotes the infiltration of T cells into tumors and enhance immune surveillance [15], we investigated whether FAK inhibition using a poly(lactic-co-glycolic) acid (PLGA) nanodrug could improve the therapy efficacy of cytotoxic T lymphocytes (CTLs)-based immunotherapy, and assessed the feasibility of positron emission tomography (PET) imaging to predict their combinational therapy efficacy (Fig. 1)
CTLs were isolated from mice pretreated with either phosphate-buffered saline (PBS) or OVA, and the dynamic interaction between CTLs and B16-OVA cells was investigated using fluorescence staining

Summary

Introduction

Cell-based therapies, such as the adoptive cell transfer of engineered T cells and natural killer cells, represent promising strategies in cancer immunotherapy. An example of such a strategy is the successful use of CD19-specific chimeric antigen receptor T cells (CAR-T cells) in the treatment of patients with relapsed B-cell lymphoma and acute lymphoblastic leukemia [1, 2]. FAK inhibition was reported to overcome the immunosuppressive tumor microenvironment and increased cytotoxic T cell infiltration [15] These findings suggest that a combination therapy involving FAK inhibition may improve the efficacy of the adoptive cell transfer of effector T cells. Strategies for the noninvasive tracking of adoptive T cells are critical for monitoring tumor infiltration and for guiding the development of novel combination therapies

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Conclusion