Abstract A016: Use of luminescent xenograft and 3D In vitro tumor models in pharmacology studies of chimeric antigen receptor-T (CAR-T) cells
Authors: Li Ruyi , Gan Shanshan , Zhang Leixin , Cuff Patrice , Wang Zhuyao , Broudy Thomas 
Published: March 2020

Chimeric antigen receptor-T (CAR-T) cell immunotherapy uses a patient’s T cells to engineer T cells with chimeric antigen receptors to attack their cancer cells. Recently the first two CAR-T therapies were approved by the U.S. Food and Drug Administration: Yescarta to treat lymphoma in adults and Kymriah to treat pediatric and young adult patients with acute lymphoblastic leukemia. With their significant efficacy shown in patients, more CAR-T therapies have begun to develop at the preclinical phases with new targets or alternative chimeric antigen designs. Here we demonstrate the use of xenograft mouse models to show the efficacy of CAR-T cells utilizing an orthotopic lymphoma and ovarian cancer subcutaneous models. In the first model, luciferase-labeled Raji (Raji-luc) cells were injected into immune-deficient B-NDG mice from Biocytogen, and 9 days after tumor inoculation, CAR-T 1 or CAR-T 2 were given to animals through a single IV injection. Approximately one week later, significant tumor growth inhibition was observed in both CAR-T cell treated groups. Additionally, at Day 37 post-tumor inoculation, all animals in the control group had died, while the CAR T treated group had a 75% survival rate. With the same batch of CAR-T cells as above, we tested their efficacy in BioDuro’s proprietary 3D culture method which is aligned to the human tumor microenvironment (3D-hTME). Raji-luc cells were mixed with CAR-T cells at Effector:Target (E: T) ratios of 1:0.5, 1:2 and 1:8, and then seeded into a semi-solid medium for 3D culture in a 96-well plate. The luminescent signals were read by and IVIS spectrum imager after 4- or 24-hours incubation at 37oC. Consistent with the in vivo result, the 3D-hTME model shows that CAR-T cells had an increasing killing effect on Raji-luc cells, with higher E:T ratio and increased incubation time. To test CAR-Ts in a solid tumor xenograft model, a similar study was completed in a luciferase-labeled SK-OV-3 (SK-OV-3-luc) subcutaneous xenograft. SK-OV-3-luc cells were inoculated subcutaneously into B-NDG mice. This was followed 9 days later by CAR-T treatment through a single IV injection. Tumor sizes were measured with caliper or by luminescent signal in mice with an IVIS spectrum imager. The results demonstrate from Day 20 on that animals treated with CAR-T cells had significantly smaller tumors as compared to control animals. In summary, utilizing xenograft models with luciferase-labeled cancer cell lines, we can investigate the efficacy of experimental CAR-T therapies to treat liquid and solid tumors. Additionally, the use of in vitro 3D-hTME culture shows promising results as a potential earlier-stage preclinical screen for the assessment of CAR T activity.

Citation Format: Ruyi Li, Shanshan Gan, Leixin Zhang, Patrice Cuff, Zhuyao Wang, Thomas Broudy. Use of luminescent xenograft and 3D In vitro tumor models in pharmacology studies of chimeric antigen receptor-T (CAR-T) cells [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2019 Oct 26-30; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2019;18(12 Suppl):Abstract nr A016. doi:10.1158/1535-7163.TARG-19-A016