dVHH22-RIT

dVHH22-RIT is a divalent nanobody-based recombinant immunotoxin (RIT) designed as a negative control for evaluating CD7-targeted therapies in T-cell acute lymphoblastic leukemia (T-ALL). It consists of a divalent nanobody (VHH22) that does not recognize the CD7 antigen, fused to PE38, a 38 kDa truncated version of Pseudomonas exotoxin A. The toxin component, PE38, is intended to inhibit protein synthesis by catalyzing the ADP-ribosylation of elongation factor 2 (EF-2) within the cell cytoplasm. In preclinical research, dVHH22-RIT is used to demonstrate that the cytotoxic effects of therapeutic candidates like dhuVHH6-PE38 are specifically mediated by CD7 binding, as dVHH22-RIT shows no binding or growth inhibition in CD7-positive cell lines or patient-derived samples.