First in-human study of in vivo imaging of ex vivo labeled CAR T cells with dual PET-MR.

Abstract

3557 Background: This is a first in human in-vivo biodistribution of ex-vivo labelled CAR T cells assessed in a cohort of patients. Cells were labelled with novel Cu-64 labelled superparamagnetic iron oxide nanoparticles (SPION) and infused IV into patients with solid tumors & tracked using clinical dual PET-MR. The study validates the clinical translation of CAR T cell in-vivo tracking in real time. Methods: Cu-64 radioisotope was bound to silica coated SPION using electrolysis plating with tin & palladium seeding. Cellular uptake of Cu-64 SPION was facilitated with a transfecting agent. Functional assays including 51Chromium release, cytometric bead array demonstrated that labelling process did not affect cytotoxicity & cytokine secretion (TNFα & IFN-g). T cells were transduced with retroviral vector constructs encoding for second-generation chimeric T-cell receptor specific for carbohydrate Lewis Y antigen. Modified T-cells were expanded ex-vivo & were labelled with Cu-64 (~300 MBq) prior to re-infusion (3 x108 labelled cells). Scanning is performed with Siemens 3T dual PET-MR scanner. Results: In this first in human in-vivo study (HREC/16/PMCC/30) a cohort of patients received ex-vivo labelled CAR T cells to determine how many labelled cells distribute to solid tumor sites within 3-5 days. Our results demonstrate that cells can be efficiently labelled (≤60%) with high cell viability (≥85%) at a sensitivity sufficient to detect labelled cells at tumor site for up to 5 days. An observed trend in SUVmean & SUVmax provided insight into efficacy & individual response to therapy. Early time points showed moderate uptake of labelled cells in lungs posterior basal segments without increased activity over next few days, suggesting a transient process. Mild, diffuse bone marrow & relatively intense uptake of labelled cells in liver & spleen suggests margination of cells to reticulo-endothelial system. Distinct PET signal at some of the tumor sites at 24 h suggests antigen specific localization & time taken to reach these sites. Excretion via hepatobiliary indicated reabsorption from GI tract & re-circulation of labelled cells. Minimal uptake in brain & heart supported safety profile of labeling agent. Conclusions: This is first in human in-vivo study to provide highly valuable visual and dynamic data in real time and provides insight into individual responses to therapy. CAR T cell functionality largely remain unchanged due to labeling process. The findings indicate that labelled cells traffic to tumor sites at later time points & remain persistent for extended period of time.

Whole-Body Imaging to Assess Cell-Based Immunotherapy: Preclinical Studies with an Update on Clinical Translation

“…64 Cu-SPIONlabeled CD19-specific CAR-T cells showed cytotoxic action against target lymphoma cells in vitro, although at a lower level than the unlabeled CAR-T cells [89]. A first-in-human clinical trial has been performed in CAR-T cells [90]. 19 F-PFC containing radiometal chelate fluorous hydroxamic acid that captures 89 Zr has visualized inflammatory lesions in mice, including an experimental inflammatory bowel disease and a periphery of tumors, presumably through phagocytosis by macrophages, both in PET and 19 F-MRI [91].…”

PET Imaging for Monitoring Cellular and Immunotherapy of Cancer

“…This study investigated the distribution of labeled cells to organs of interest and tumor sites within 3-5 days, using PET/MRI. 55 Another example involves the use of [ 64 Cu]Cu-pyruvaldehyde-bis(N4-methylthiosemicarbazone) ([ 64 Cu]Cu-PTSM), a PET perfusion tracer, which relied on passive diffusion of the lipophilic molecule to track immune cells in healthy mice. 56 However, despite the promise of longer-lived isotopes, rapid efflux of 64 Cu poses a challenge for long-term cellular retention, limiting imaging possibilities to a few days.…”

“…In a pioneering human study, Lewis Y antigen-specific CAR T cells specific were labeled ex vivo with 64 Cu-labeled SPIONs and reinfused into patients with solid tumors. This study investigated the distribution of labeled cells to organs of interest and tumor sites within 3–5 days, using PET/MRI 55 . Another example involves the use of [ 64 Cu]Cu-pyruvaldehyde-bis(N4-methylthiosemicarbazone) ([ 64 Cu]Cu-PTSM), a PET perfusion tracer, which relied on passive diffusion of the lipophilic molecule to track immune cells in healthy mice 56 .…”

In Vivo Cell Tracking Using PET: Opportunities and Challenges for Clinical Translation in Oncology

“…Longer-lived PET isotopes offer the potential for tracking cells over several days: Copper-64 ([ 64 Cu], t 1/2 = 12.7 h) conjugated to nanoparticles has been investigated for the labelling of CD19-specific CAR T-cells using both superparamagnetic iron oxide nanoparticles (SPION) [26] and gold nanoparticles [27]. In a first-in-human study, CAR T-cells specific for the carbohydrate Lewis Y antigen were labelled ex vivo with 64 Cu-labelled SPIONs, facilitated by a transfecting agent, and reinfused into patients with solid tumours to investigate the distribution of labelled cells to body organs and tumour sites within 3-5 days, using a hybrid PET/MRI approach [28]. [ 64 Cu]Cu-pyruvaldehyde-bis(N4methylthiosemicarbazone) ([ 64 Cu]Cu-PTSM), a commonly used PET perfusion tracer, has also been used to study the biodistribution of labelled cells in healthy mice [29][30][31].…”