The research focused on overcoming the immune response induced by murine-derived CAR T cells, which can reduce their persistence and therapeutic efficacy. To achieve this, the researchers isolated a human scFv named Hu1E7 from a phage display library. They then fused Hu1E7 to the hinge region of CD8α, the transmembrane domain of CD28, three intracellular costimulatory domains (CD28, 4-1BB, and CD27), and a CD3ζ signaling domain, creating the Hu1E7-CAR4 T cells.

The team compared the anti-tumor activity and functionality of Hu1E7-CAR4 T cells with murine-derived CAR T cells, including mFMC63-CAR2 T cells (BBζ) and mFMC63-CAR3 T cells (BB27ζ). In preclinical evaluations, Hu1E7-CAR4 T cells demonstrated superior anti-tumor activity against CD19-positive Raji target cells, similar to mFMC63-CAR4 T cells (28BB27ζ). Both Hu1E7-CAR4 and mFMC63-CAR4 T cells exhibited comparable cytotoxicity and proliferation.

Interestingly, the researchers observed that Hu1E7-CAR4 T cells secreted lower levels of cytokines, such as IFN-γ and TNF-α, compared to mFMC63-CAR4 T cells. This may be attributed to the lower binding affinity of Hu1E7-CAR4 T cells. Nevertheless, the findings showcased the successful creation of CAR T cells incorporating a fully human-derived scFv specific to CD19-positive cancer cells.

The next step for this research involves in vivo studies to further evaluate the anti-tumor efficacy and safety of Hu1E7-CAR4 T cells in comparison to mFMC63-CAR4 T cells.

Prof. Pa-Thai Yenchitsomanus, the senior author of the study, commented, “Our research marks a significant milestone in CAR T-cell therapy. By developing Hu1E7-CAR4 T cells with fully human-derived components, we aim to address the challenges associated with immune responses and improve the persistence and therapeutic effectiveness of CAR T-cell treatment for B-cell malignancies. We look forward to advancing our studies through in vivo investigations to potentially revolutionize the treatment landscape for these patients.”