The use of 2-Sulfonylpyrimidines as warheads for targeted covalent inhibition

Abstract

Targeted Covalent Inhibitors (TCIs) focused on cysteine arylation have historically used a limited number of electrophilic “warheads”. Whilst the acrylamide “warhead” has been the top choice in medicinal chemistry for the synthesis of modern TCIs, it has faced challenges in the selectivity and stability profiles. The small structure of the acrylamide functional group has little to offer when it comes to functionalization to improve these profiles which is one of the main challenges in the reactivity of these TCIs. This project investigates the design, synthesis, and use of 2- Sulfonylpyrimidines (2-SPs) as “warheads” for TCIs as an effective replacement. Ibrutinib, an FDA approved drug containing an acrylamide warhead which targets B-cell malignancies by covalently binding to Cys481 at the surface of BTK active site is used as the model system. It was quickly discovered that functionalised 2-SPs showed good activity in BTK in vitro studies, comparable to the one of Ibrutinib. Several lead compounds were taken for further in vitro and in vivo tests, showing better results than the parent compound, including plasma stability. A few TCIs also showed reduced off-target binding on a panel of 135 tested kinases in comparison to Ibrutinib. This study provides valuable design criteria, and the results show proof that 2-SPs are highly effective as warheads for TCIs. Following analysis of assays results, a trend observed was that EWG functionalised TCIs show the best activity. However, most of these TCIs contain an ester or an amide which are hydrolysed in plasma stability assays, a known metabolic pathway. This is what inspired the second chapter in this thesis which looks at a reactivity switch on the pyrimidine ring by implementing EDG which are not susceptible to hydrolysis whilst maintaining the electrophilicity at the 2- position. A small number of pyrimidines were carefully designed and synthesised containing EDG on the 2-SP ring. These were tested against model thiols such as NACME an GSH in NMR reactivity studies at various pH levels to calculate the rate of reaction. The aim of this project was to remove the stability limitation that some initial TCIs presented in plasma stability assay.

More information

Identifiers

ORCID for Ruxandra Moraru: orcid.org/0000-0001-5169-4792

ORCID for Matthias Baud: orcid.org/0000-0003-3714-4350

Catalogue record

Export record