1. Anti-CD22-MCC-DM1 and MC-MMAF conjugates: impact of assay format on pharmacokinetic parameters determination
Wai Lee T Wong, Christopher Nelson, Ola Saad, James Michael Elliott, Chien Lee, Jon Akutagawa, Helga Raab, Jakub Baudys, Charity Bechtel, Saileta Prabhu, David Xie, Fred Jacobson, Pamela Chan, Allen Ebens, Jean-Philippe Stephan, Richard Vandlen Bioconjug Chem . 2008 Aug;19(8):1673-83. doi: 10.1021/bc800059t.
CD22 represents a promising target for antibody-drug conjugate therapy in the context of B cell malignancies since it rapidly internalizes, importing specifically bound antibodies with it. To determine the pharmacokinetic parameters of anti-CD22-MCC-DM1 and MC-MMAF conjugates, various approaches to quantifying total and conjugated antibody were investigated. Although the total antibody assay formats gave similar results for both conjugates, the mouse pharmacokinetic profile for the anti-CD22-MCC-DM1 and MC-MMAF appeared significantly different depending on the conjugated antibody assay format. Since these differences significantly impacted the PK parameters determination, we investigated the effect of the drug/antibody ratio on the total and conjugated antibody quantification using multiple assay formats. Our investigations revealed the limitations of some assay formats to quantify anti-CD22-MCC-DM1 and MC-MMAF with different drug load and in the context of a heterogeneous ADC population highlight the need to carefully plan the assay strategy for the total and conjugated antibody quantification in order to accurately determine the ADC PK parameters.
2. Antibody-Drug Conjugates (ADCs) Derived from Interchain Cysteine Cross-Linking Demonstrate Improved Homogeneity and Other Pharmacological Properties over Conventional Heterogeneous ADCs
Jorge Monteon, Abel Bermudez, Maureen Fitch-Bruhns, Edward H Ha, Christopher R Behrens, Kristy Venstrom, Sindy Liao-Chan, Jonathan Melnick, Edward H van der Horst, Simeon Bowers, Tiffany Wong, Amanda Valdiosera, Paul Sauer, Mark R Flory, Lawrence L Chinn, Derrick Houser, Gary Probst, Thi-Sau Migone, Jan-Willem Theunissen, Zoia Levashova, David Y Jackson, Randall L Halcomb Mol Pharm . 2015 Nov 2;12(11):3986-98. doi: 10.1021/acs.molpharmaceut.5b00432.
Conventional antibody-drug conjugates (ADCs) are heterogeneous mixtures of chemically distinct molecules that vary in both drugs/antibody (DAR) and conjugation sites. Suboptimal properties of heterogeneous ADCs have led to new site-specific conjugation methods for improving ADC homogeneity. Most site-specific methods require extensive antibody engineering to identify optimal conjugation sites and introduce unique functional groups for conjugation with appropriately modified linkers. Alternative nonrecombinant methods have emerged in which bifunctional linkers are utilized to cross-link antibody interchain cysteines and afford ADCs containing four drugs/antibody. Although these methods have been shown to improve ADC homogeneity and stability in vitro, their effect on the pharmacological properties of ADCs in vivo is unknown. In order to determine the relative impact of interchain cysteine cross-linking on the therapeutic window and other properties of ADCs in vivo, we synthesized a derivative of the known ADC payload, MC-MMAF, that contains a bifunctional dibromomaleimide (DBM) linker instead of a conventional maleimide (MC) linker. The DBM-MMAF derivative was conjugated to trastuzumab and a novel anti-CD98 antibody to afford ADCs containing predominantly four drugs/antibody. The pharmacological properties of the resulting cross-linked ADCs were compared with analogous heterogeneous ADCs derived from conventional linkers. The results demonstrate that DBM linkers can be applied directly to native antibodies, without antibody engineering, to yield highly homogeneous ADCs via cysteine cross-linking. The resulting ADCs demonstrate improved pharmacokinetics, superior efficacy, and reduced toxicity in vivo compared to analogous conventional heterogeneous ADCs.