Development of Novel Quaternary Ammonium Linkers for Antibody–Drug Conjugates

Abstract

A quaternary ammonium-based drug-linker has been developed to expand the scope of antibody-drug conjugate (ADC) payloads to include tertiary amines, a functional group commonly present in biologically active compounds. The linker strategy was exemplified with a b-glucuronidase-cleavable auristatin E construct. The drug-linker was found to efficiently release free auristatin E (AE) in the presence of b-glucuronidase and provide ADCs that were highly stable in plasma. Anti-CD30 conjugates comprised of the glucuronide-AE linker were potent and immunologically specific in vitro and in vivo, displaying pharmacologic properties comparable with a carbamate-linked glucuronide-monomethylauristatin E control. The quaternary ammonium linker was then applied to a tubulysin antimitotic drug that contained an N-terminal tertiary amine that was important for activity. A glucuronide-tubulysin quaternary ammonium linker was synthesized and evaluated as an ADC payload, in which the resulting conjugates were found to be potent and immunologically specific in vitro, and displayed a high level of activity in a Hodgkin lymphoma xenograft. Furthermore, the results were superior to those obtained with a related tubulysin derivative containing a secondary amine N-terminus for conjugation using previously known linker technology. The quaternary ammonium linker represents a significant advance in linker technology, enabling stable conjugation of payloads with tertiary amine residues.Mol Cancer Ther; 15(5); 938-45. Ó2016 AACR.

Optimization of a PEGylated Glucuronide-Monomethylauristatin E Linker for Antibody–Drug Conjugates

“…Finally, a modest upward trend in drug delivery over aCD30-3 was observed with the incorporation of the self-stabilizing maleimide, as shown in aCD30-4. As observed previously for drug-linkers containing mDPR (15,18), ADC bearing drug-linker 4 was highly stable over the course of 7 days at 37 C in rat plasma, whereas ADCs composed of MC-containing drug-linkers 2 and 3 underwent extensive de-conjugation under the same conditions (Supplementary Fig. S2).…”

PET-Guided Evaluation and Optimization of Internalized Antibody–Drug Conjugates Targeting Erythropoietin-Producing Hepatoma A2 Receptor

“…For a given drug, the chemical conjugation (method, site, and stoichiometry) is crucial to the effectiveness of ADC in vivo (32). Several approaches can be used for conjugation of the drug onto the mAb, such as conjugation on the e-amino terminus of lysine residues or the sulfhydryl portion of a reduced cysteine residue or tertiary amine functional group (33,34). Future work should compare different methods to link the drug to the mAb and evaluate which method has smaller variations in antibody pharmacokinetics behaviors.…”

Tubulin Inhibitor-Based Antibody-Drug Conjugates for Cancer Therapy

“…The acid-labile cleavable linkers, such as hydrazone functionalities, β-glucuronide containing linkers, or quaternary ammonium linkers have also been used for several auristatin ADCs for PK profile evaluation ( Scheme 4 C) [ 75 , 92 , 93 ]. To date, these compounds have not advanced to clinical trials.…”

“…Li et al developed a biparatopic HER2-targeting ADC using tubulysin as payload, which showed superior antitumor activity over T-DM1 in tumor models representing various patient subpopulations [ 120 ]. The recently developed tubulysin ADCs with a novel quaternary ammonium linker have great stability profiles and potent anticancer activity based on in vitro and in vivo evaluation ( Scheme 6 B) [ 93 ]. Other than this, tubulysin ADCs are quite different from MMAE/MMAF and DM1/DM4 ADCs.…”