Mutated Flt3Lg Provides Reduced Flt3 Recycling Compared to Wild-Type Flt3Lg and Retains the Specificity of Flt3Lg-Based CAR T-Cell Targeting in AML Models

Abstract

The cells of acute myeloid leukemia are defined by clonal growth and heterogenous immunophenotypes. Chimeric antigen receptors (CARs) commonly recognize molecular targets by single-chain antibody fragments (scFvs) specific to a tumor-associated antigen. However, ScFvs may form aggregates, thus stimulating tonic CAR T-cell activation and reducing CAR T-cell functioning in vivo. Harnessing natural ligands as recognition parts of CARs, specific targeting of membrane receptors can be achieved. Previously, we presented ligand-based Flt3-CAR T-cells targeting the Flt3 receptor. The extracellular part of Flt3-CAR consisted of full-size Flt3Lg. Meanwhile, upon recognition, Flt3-CAR may potentially activate Flt3, triggering proliferative signaling in blast cells. Moreover, the long-lasting presence of Flt3Lg may lead to Flt3 downregulation. In this paper, we present mutated Flt3Lg-based Flt3m-CAR (‘m’—for ‘mutant’) T-cells targeting Flt3. The extracellular part of Flt3m-CAR consists of full-length Flt3Lg-L27P. We have determined that ED50 for recombinant Flt3Lg-L27P produced in CHO cells is at least 10-fold higher than for the wild-type Flt3Lg. We show that the mutation in the recognizing domain of Flt3m-CAR did not affect the specificity of Flt3m-CAR T-cells when compared to Flt3-CAR T-cells. Flt3m-CAR T-cells combine the specificity of ligand–receptor recognition with reduced Flt3Lg-L27P bioactivity, leading to potentially safer immunotherapy.

Identification of potential biomarkers and therapeutic targets related to post-traumatic stress disorder due to traumatic brain injury

“…However, recent studies have also found that ETFDH plays an important role in the development of several diseases [ 55 , 56 ], suggesting the need for future research in order to explore its association with biological pathways that drive PTSD.Fms-related receptor tyrosine kinase 3 ligand (FLT3LG) is a growth factor that binds to and forms non-covalent dimers with FLT3 (CD135), acting as an agonist [ 57 ]. FLT3LG stimulates the differentiation and proliferation of dendritic cells [ 58 ] and has a potential therapeutic value in treating autoimmune diseases and tumors [ 57 , 59 ]. However, there is relatively limited research on FLT3LG, and further exploration is needed regarding its expression levels, functions, and clinical value in various diseases [ 60 ].…”