Reduction-alkylation strategies for the modification of specific monoclonal antibody disulfides.

Site-specific conjugation of small molecules and enzymes to monoclonal antibodies has broad utility in the formation of conjugates for therapeutic, diagnostic, or structural applications. Precise control over the location of conjugation would yield highly homogeneous materials that could have improved biological properties. We describe for the first time chemical reduction and oxidation methods that lead to preferential cleavage of particular monoclonal antibody interchain disulfides using the anti-CD30 IgG1 monoclonal antibody cAC10.

In vivo drug-linker stability of an anti-CD30 dipeptide-linked auristatin immunoconjugate.

Effective antibody-drug conjugates (ADC) combine high drug-linker stability in circulation and efficient intratumoral release of drug. Conjugation of monomethyl auristatin E (MMAE) to the anti-CD30 monoclonal antibody (mAb), cAC10, produced a selective and potent ADC against CD30(+) anaplastic large cell lymphoma and Hodgkin's disease models. This ADC, cAC10-valine-citrulline-MMAE, uses a protease-sensitive dipeptide linker designed to release MMAE by lysosomal cathepsin B in target cells but maintain a stable linkage and attenuate drug potency in circulation.

Effects of drug loading on the antitumor activity of a monoclonal antibody drug conjugate.

Purpose: An antibody-drug conjugate consisting of monomethyl auristatin E (MMAE) conjugated to the anti-CD30 monoclonal antibody (mAb) cAC10, with eight drug moieties per mAb, was previously shown to have potent cytotoxic activity against CD30(+) malignant cells. To determine the effect of drug loading on antibody-drug conjugate therapeutic potential, we assessed cAC10 antibody-drug conjugates containing different drug-mAb ratios in vitro and in vivo.

Experimental Design: Coupling MMAE to the cysteines that comprise the interchain disulfides of cAC10 created an antibody-drug conjugate population, which was purified using hydrophobic interaction chromatography to yield antibody-drug conjugates with two, four, and eight drugs per antibody (E2, E4, and E8, respectively).