Characterization of a switchable chimeric antigen receptor platform in a pre-clinical solid tumor model

Abstract

The universal modular chimeric antigen receptor (UniCAR) platform redirects CAR-T cells using a separated, soluble targeting module with a short half-life. This segregation allows precise controllability and flexibility. Herein we show that the UniCAR platform can be used to efficiently target solid cancers and using a pre-clinical prostate cancer model which overexpresses prostate stem cell antigen (PSCA). Short-term administration of the targeting module to tumor bearing immunocompromised mice engrafted with human UniCAR-T cells significantly delayed tumor growth and prolonged survival of recipient mice both in a low and high tumor burden model. In addition, we analyzed phenotypic and functional changes of cancer cells and UniCAR-T cells in association with the administration of the targeting module to reveal potential immunoevasive mechanisms. Most notably, UniCAR-T cell activation induced upregulation of immune-inhibitory molecules such as programmed death ligands. In conclusion, this work illustrates that the UniCAR platform mediates potent anti-tumor activity in a relevant and solid tumor model.

From mono- to bivalent: improving theranostic properties of target modules for redirection of UniCAR T cells against EGFR-expressing tumor cells in vitro and in vivo

“…Keeping the long-term persistence of CAR-engrafted T cells in mind [ 41 , 42 ], EGFR-targeted therapy requires the shutdown of adoptively transferred immune effector cells to avoid permanent destruction of healthy tissues. Thus, we came up with the idea to manage the safety issue by separating the functional domains of CAR constructs and developed a novel platform technology termed UniCAR [ 22 – 27 ]. This modular tumor targeting strategy is based on T cells which are genetically modified to express the UniCAR and are per se inactive.…”

“…So far, we have established a series of TMs for the UniCAR system including against CD33, CD123, CD19, PSCA, PSMA, and GD2 [ 22 – 27 ]. All these and other constructs (Bachmann, unpublished) were functional without any further optimization, although affinity of these TMs to the respective target cell varied in a wide range.…”

“…Recently, we described the modular UniCAR platform technology for retargeting of T cells to various tumor-associated surface antigens (TAAs) including EGFR that meets this criterion [ 21 – 27 ]. It represents a unique chimeric antigen receptor (CAR) T cell therapy combining T cells engrafted with a universal CAR (UniCAR) and an antibody (Ab)-based component referred to as target module (TM) (Figure 1 ).…”

Recent Advances in Allogeneic CAR-T Cells

“…Indeed, the binding affinity of the CAR for FITC was measured as Kd = 30 pM (3 × 10 −11 M) and the affinity of the folate for FRα receptor on MDA-MB-231 cells was determined to be Kd = 1.0 nM [82]. Anti-La 5B9 mAb that recognizes a continuous sequence of 10 amino acids (5B9 tag) of the nuclear protein La/SS-B was used as a switch molecule that was linked to CAR and the 5B9 tag was linked to scFv recognizing TAA [83]. In addition, FITC-HM-3 bifunctional molecule (FHBM) was created as a switch molecule for novel switchable dual-receptor CAR-engineered T cells.…”

MAGE-A1 in lung adenocarcinoma as a promising target of chimeric antigen receptor T cells

“…One of the most substantial impediments for the development of CAR-T therapy for solid tumors is the identification of tumor antigens. Currently, most tumor-associated antigens (TAAs) that are utilized as targets for CAR-T therapy are not tumor-specific, which means that they are expressed in both malignant and normal tissues [13]. A number of strategies have been developed to increase the controllability of CAR-T cells to minimize the on-target/off-tumor toxicities and typical side effects, such as cytokine release syndrome [14, 15].…”