A human, compact, fully functional anti-ErbB2 antibody as a novel antitumour agent

Abstract

A new human, compact antibody was engineered by fusion of a human, antitumour ErbB2-directed scFv with a human IgG1 Fc domain. Overexpression of the ErbB2 receptor is related to tumour aggressiveness and poor prognosis. This new immunoagent meets all criteria for a potential anticancer drug: it is human, hence poorly or not immunogenic; it binds selectively and with high affinity to target cells, on which it exerts an effective and selective antiproliferative action, including both antibody-dependent and complement-dependent cytotoxicity; it effectively inhibits tumour growth in vivo. Its compact molecular size should provide for an efficient tissue penetration, yet suitable to a prolonged serum half-life.

Structural features for the mechanism of antitumor action of a dimeric human pancreatic ribonuclease variant

“…17 They differ for the swapping of the N-termini (residues 1-15) within a substantially identical quaternary framework. [18][19][20] In both isoforms, the dimeric interface is formed by the hinge peptides (residues [16][17][18][19][20][21][22] and the helices (residues [23][24][25][26][27][28][29][30][31][32][33][34] that comprise the four cysteines forming the two interchain disulfide bridges (Cys31-Cys32 0 and Cys32-Cys31 0 ) and the side chains of Leu28 and 28 0 that form stabilizing hydrophobic interactions across the molecular twofold axis. 18,20 In the most abundant swapped form, MxM-BSRNase, the dimeric interface also includes the closed interface arising from the swapped elements.…”

“…16 Moreover, this dimer is highly unstable in aqueous solution, where it is present mostly as a monomer, and its occurrence in the solid state has been probably favored by the low dielectric constant of the precipitant solution. 30 Different approaches have been proposed to confer cytotoxicity to HP-RNase; they include (a) sitedirected mutagenesis to weaken its interaction with RI, 23 (b) conjugation of HP-RNase to protein, peptide, and antibodies, which could enhance the uptake by target cells, 31,32 (c) transformation of the protein into a stable dimer capable to evade RI. 33 Following the latter strategy, Piccoli et al 34 have mutated four residues at the helix-II region according to BSRNase sequence (Gln28!Leu, Arg31!Cys, Arg32!Cys, and Asn34!Lys) and have produced a covalent dimeric variant (HHP-RNase), enzymatically active and selectively cytotoxic for several malignant mouse and human cell lines.…”

Effects of a human compact anti-ErbB2 antibody on prostate cancer

“…The PER.C6 ® cell line (Crucell N.V., Leiden, The Netherlands), transfected with the recombinant plasmid pIgPlus (19), was cultured according to the manufacturer's recommendations.…”

“…Recently, we produced a novel fully human anti-ErbB2 immunoagent (19), engineered by fusing Erbicin, a human anti-ErbB2 single-chain antibody fragment (scFv) (20), with the Fc region of human IgG1.…”

“…It has been reported that Erb-hcAb is capable of selectively binding to malignant cells that express ErbB2, and of inhibiting their growth in vitro and in vivo, with no effects on ErbB2-negative cells. Moreover, Erb-hcAb is endowed with both antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC) effects (19,21).…”