Nectin4-targeted VHH-CAR-T cells show potency against bladder cancer

Announcing a new article publication for BIO Integration journal. Bladder cancer (BLCA) is one of the most common malignancies and the second most frequent urogenital tract tumor. Cell and gene therapy, which offer many advantages in treating BLCA, are urgently needed. However, there is an important limitation of the currently reported single chain antibody used as a chimeric antigen receptor (CAR) targeting domain. Specifically, CAR aggregation leads to CAR-T depletion, which may originate from the linker peptide and folding stability between the variable domains (VH and VL) of the single chain antibody of the CAR. Humanized, small size, strong affinity single domain antibodies (variable domain of heavy chain of heavy-chain antibody [VHH]) derived from camelids are promising alternatives.

Second-generation Nectin4-targeted VHH-CAR-T cells were constructed and the specific killing efficacy was determined against BLCA cells in vitro. VHH Nectin4-CAR lentivirus was transduced into human T cells and CAR-T cell phenotypes were analyzed by flow cytometry. Cell killing efficacy was assessed using Nectin4-positive BLCA cells (SW780 and RT4) and Nectin4-negative U87-MG cells as controls using the xCELLigence Real Time Cell Analysis system. Cytokine secretion expression (IFN-γ and IL-2) were measured by an enzyme-linked immunosorbent assay.

VHH^Nectin4-CAR lentivirus treatment increased the proportion of CD4+ T and memory T cells. VHH^Nectin4-CAR-T cells had increased specific killing ability compared to the control using VH-VL-based CAR-T cells, specifically recognized Nectin4⁺ BLCA cells, secreted cytokines, and mediated cell apoptosis. Furthermore, VHH^Nectin4-CAR-T had no effect on Nectin4^- U87-MG cell growth.
VHH^Nectin4-CAR-T cells were established with potent killing ability that specifically recognized Nectin4⁺ BLCA cells in vitro.