Aminopyrimidine derivatives as new protein kinase inhibitors endowed with anticancer activity.

Pyrimidine-based scaffold is typical of some of the most promising anticancer agents recently discovered. Indeed, though biologics currently dominate clinical scenarios and seem ready to revolutionize cancer therapies, heterocyclic-based small molecules remain of great prominence continuing to play significant roles in the development of innovative treatments. Small molecules display some favorable pharmacological advantages and oncology drug discovery has significantly benefited from progress in understanding how to target enzymes intimately involved in cancer expression and proliferation with small molecules. Nitrogen-based heterocyclic nuclei have been the core parts of these new entities, representing today the 75% of the approved anticancer drug. In particular, pyrimidines are currently considered privileged scaffolds since they show intrinsically a wide range of biological activities. Many aminopyrimidine derivatives exerted their anticancer activity through inhibiting different types of Protein Kinases (PKs) as they are considered as bioisosteres to purine scaffold from which ATP is formed. Kinase deregulation has emerged as a relevant mechanism by which cancer cells evade normal physiological constraints and kinases inhibitors have become one of the most intensively pursued classes of recent antitumoral drugs. Owing to the significance of pyrimidine derivatives as anticancer agents through kinase inhibition and our longstanding expertise in pyrimidines drug discovery, we designed and synthesized various classes of anilino and bis-anilinopyrimidines. Most of them were found active in in vitro HTRF inhibition assays in low nanomolar range against one or more kinases, like EGFR, c-KIT, VEGFR, PDGFR, Akt and AURKA, wild type or mutated and double-mutated isoforms. Some compounds were also crystallized in the active site of some kinases, showing a preference for DFG-in or DFG-out conformation. Subsequently, the antitumor activity of selected compounds was evaluated on three different human cancer types chosen on the basis of their unsatisfactory therapeutic strategies and poor prognosis: glioblastoma multiforme (U-87 MG cells), triple-negative breast cancer (MDA-MB231 cells), colon adenocarcinoma (HT-29 cells), tongue squamous carcinoma (CAL-27 cells) and hypopharyngeal squamous carcinoma (FaDu cells). Various pyrimidines demonstrated to also hinder cell proliferation and cell cycle and to induce apoptosis in all cell lines, without exerting cytotoxic effects at the same concentrations. The data coming from the biological assays will be shown and discussed.