Synthesis and evaluation of pyrrolobenzodiazepine dimer antibody-drug conjugates with dual β-glucuronide and dipeptide triggers

• Published in: European journal of medicinal chemistry Vol. 179; pp. 591 - 607
• Main Authors: Gregson, Stephen J., Barrett, Allison M., Patel, Neki V., Kang, Gyoung-Dong, Schiavone, Davide, Sult, Erin, Barry, Conor S., Vijayakrishnan, Balakumar, Adams, Lauren R., Masterson, Luke A., D'Hooge, Francois, Snaith, Mike, Harper, Jay, Hartley, John A., Howard, Philip W.
• Format: Journal Article
• Language: English
• Published: ISSY-LES-MOULINEAUX Elsevier Masson SAS 01.10.2019; Elsevier
• Subjects: Antibody-drug conjugate; Chemistry, Medicinal; Life Sciences & Biomedicine; Pharmacology & Pharmacy; Prodrug; Pyrrolobenzodiazepine; Science & Technology; Serum stability; β-Glucuronidase; β-Glucuronidase; Serum stability; Prodrug; Pyrrolobenzodiazepine; Antibody-drug conjugate; DESIGN; EFFICACY; CANCER; POTENT; CROSS-LINKING AGENT; IN-VITRO EVALUATION; beta-Glucuronidase; SELECTIVE THERAPY; SPECTRUM ANTITUMOR-ACTIVITY; SJG-136 NSC-694501
• ISSN: 0223-5234; 1768-3254; 1768-3254
• DOI: 10.1016/j.ejmech.2019.06.044

Antibody-drug conjugates (ADCs) containing pyrrolobenzodiazepine (PBD) dimers are currently being evaluated in human oncology clinical trials with encouraging results. To further improve the therapeutic window, next-generation PBD drug-linker design has focused on the inclusion of additional tumor-selective triggers and use of lower-potency PBDs. β-Glucuronidase is a well-known target for discovery prodrugs due to increased presence in tumor cells and microenvironment. In this study, a β-glucuronidase cleavable cap was investigated at the PBD N10-position and compared with corresponding free imine ADCs. SG3600 (glucuronide) ADCs showed in vitro and in vivo efficacy/tolerability comparable to SG3400 (imine) ADCs, and good 50% inhibitory concentration differentials were observed in vitro between control non–antigen-targeted ADCs and targeted ADCs. Dependence on β-glucuronidase for SG3600 activity was demonstrated through CRISPRCas9 knockdown studies and addition of exogenous β-glucuronidase. SG3600 showed better serum stability, improved conjugation efficiency and was able to reach high drug-to-antibody ratio without aggregation. [Display omitted] •β-glucuronidase cleavable cap maintained efficacy for targeted antibody-drug conjugates.•Antibody-drug conjugate format essential for activity of the β-glucuronide derivative.•β-glucuronidase CRISPR knockdown renders β-glucuronide antibody-drug conjugates inactive.•Conjugation of β-glucuronide to high drug-to-antibody ratio was possible without aggregation.•Serum stability improved for trastuzumab-C239i-β-glucuronide compared to imine conjugate.