August 25th
Characterizing and understanding the formation of cysteine conjugates and other by-products in a random, lysine-linked antibody drug conjugate
https://www.tandfonline.com/doi/full/10.1080/19420862.2021.1974150#abstract
Abstract
This study describes the characterization of conjugation sites for a random, lysine conjugated 2-iminothiolane (2-IT) based antibody-drug-conjugate synthesized from an IgG1 antibody and a duocarmycin analog-based payload-linker. Of the 80 putative lysine sites, 78 were found to be conjugated via tryptic peptide mapping and LC-HRMS. Surprisingly, seven cysteine-linked conjugated peptides were also detected resulting from the conjugation of cysteine residues derived from the four inter-chain disulfide bonds during the reaction. This unexpected finding could be attributed to the free thiols of the 2-IT thiolated antibody intermediates and/or the 4-mercaptobutanamide by-product resulting from the hydrolysis of 2-IT. These free thiols could cause the four inter-chain disulfide bonds of the antibody to scramble via intra- or inter-molecular attack. The presence of only pair of non-reactive (unconjugated) lysine residues, along with the four intact intra-chain disulfide bonds, is attributed to their poor accessibility, which is consistent with solvent accessibility modeling analysis. We also discovered a major by-product derived from the hydrolysis of the amidine moiety of the N-terminus conjugate. In contrast, the amidine moiety in lysine-linked conjugates appeared stable. Based on our results, we propose plausible formation mechanisms of cysteine-linked conjugates and the hydrolysis of the N-terminus conjugate, which provide scientific insights that are beneficial to process development and drug quality control.
August 18th
Identification of JNJ-61803534, a RORγt Inverse Agonist for the Treatment of Psoriasis
https://pubs.acs.org/doi/abs/10.1021/acs.jmedchem.5c00390
Abstract
The retinoic acid receptor-related orphan receptor gamma t (RORγt) is a nuclear transcription factor expressed in both innate and adaptive immune cells, driving Th17 cell differentiation and IL-17 production. The IL-23/IL-17 pathway is implicated in autoimmune and inflammatory diseases, and biologics that target IL-23/IL-17 signaling are efficacious in the treatment of psoriasis and psoriatic arthritis. RORγt, at the core of this pathway, represents an attractive opportunity for small-molecule intervention; however, combining high potency, nuclear receptor selectivity, and good physicochemical properties remains a challenge for RORγt inverse agonists. Recently, thiazole amides have been identified as potent RORγt inverse agonists; however, they often suffer from CYP450 autoinduction in the rat, precluding further development. Herein, we describe the discovery and development of potent and selective thiazole bisamide RORγt inverse agonists that avoid autoinduction in the rat. This effort culminated in the discovery of JNJ-61803534, which advanced into phase 1 clinical trials.
August 11th
Accelerating the Hit-To-Lead Optimization of a SARS-CoV-2 Mpro Inhibitor Series by Combining High-Throughput Medicinal Chemistry and Computational Simulations
https://pubs.acs.org/doi/abs/10.1021/acs.jmedchem.4c02941
Abstract
In this study, we performed the hit-to-lead optimization of a SARS-CoV-2 Mpro diazepane hit (identified by computational methods in a previous work) by combining computational simulations with high-throughput medicinal chemistry (HTMC). Leveraging the 3D structural information of Mpro, we refined the original hit by targeting the S1 and S2 binding pockets of the protein. Additionally, we identified a novel exit vector pointing toward the S1′ pocket, which significantly enhanced the binding affinity. This strategy enabled us to transform, rapidly with a limited number of compounds synthesized, a 14 μM hit into a potent 16 nM lead compound, for which key pharmacological properties were subsequently evaluated. This result demonstrated that combining computational technologies such as machine learning, molecular docking, and molecular dynamics simulation with HTMC can efficiently accelerate hit identification and subsequent lead generation.
August 4th
Discovery of AMG 193, an MTA-Cooperative PRMT5 Inhibitor for the Treatment of MTAP-Deleted Cancers
https://pubs.acs.org/doi/abs/10.1021/acs.jmedchem.4c03121
Abstract
MTAP deletion occurs in 10–15% of all human cancers due to its proximity to the tumor suppressor gene CDKN2A. The loss of MTAP leads to accumulation of methylthioadenosine (MTA), which shares structural similarity to S-adenosyl methionine (SAM), the methyl donor for the cell-essential protein arginine methyltransferase 5 (PRMT5). By competing with SAM, MTA partially inhibits PRMT5, making MTAP-deleted tumors susceptible to further PRMT5 inhibition. Herein, we report the discovery of MTA-cooperative PRMT5 inhibitor AMG 193, a molecule that inhibited the proliferation of HCT116 MTAP-deleted cells with ∼40x selectivity over HCT116 MTAP-WT cells. AMG 193 was orally efficacious in mouse xenografts of endogenous MTAP-null tumors such as BxPC-3 (96% TGI @ 100 mg/kg QD) and U87MG (88% TGI @ 100 mg/kg QD). Preclinical data indicate that AMG 193 is brain-penetrant. AMG 193 is currently in Phase I/II clinical trials for the treatment of advanced MTAP-deleted solid tumors.
