Engineering and characterization of a divalent single-chain Fv angiotensin II fusion construct of the monoclonal antibody CC49

For the therapy of solid tumors, co-administration of angiotensin II (AngII) results in an increased uptake of drugs into the tumor interstitium. We have engineered a dimeric sc(Fv)2-AngII fusion construct that combines the superior kinetics of covalent dimeric scFvs [sc(Fv)2], recognizing the pancarcinoma tumor-associated antigen 72 (TAG-72), with the advantageous intrinsic activity of AngII. The binding characteristics of the fusion construct were unaltered by the addition of the AngII sequence [affinity constant KA 1.18 x 107 and 8.42 x 106 M-1 for sc(Fv)2 and sc(Fv)2-AngII, respectively]. The binding of the fusion construct to the angiotensin receptor (AT1) was similar to AngII, and the arterial contraction was 16 ± 1% of the response observed with norepinephrine. In animal studies, the radiolabeled sc(Fv)2-AngII construct exhibited similar uptake and a more homogeneous distribution within the tumor as compared to sc(Fv)2