JORDA, Radek, HAVLÍČEK, Libor, ŠTURC, Antonín, TUŠKOVÁ, D., DAUMOVÁ, L., ALAM, M., ŠKERLOVÁ, Jana, NEKARDOVÁ, Michaela, PEŘINA, Miroslav, POSPÍŠIL, Tomáš, ŠIROKÁ, Jitka, URBÁNEK, Lubor, PACHL, Petr, ŘEZÁČOVÁ, Pavlína, STRNAD, Miroslav, KLENER, P., KRYŠTOF, Vladimír. 3,5,7-Substituted Pyrazolo[4,3- d]pyrimidine Inhibitors of Cyclin-Dependent Kinases and Their Evaluation in Lymphoma Models. Journal of Medicinal Chemistry. 2019, 62(9), 4606-4623. ISSN 0022-2623. E-ISSN 1520-4804

Cyclin-dependent kinases are therapeutic targets frequently deregulated in various cancers. By convenient alkylation of the 5-sulfanyl group, we synthesized 3-isopropyl-7-[4-(2-pyridyl)benzyl]amino-1(2)H-pyrazolo[4,3-d]pyrimidines with various substitutions at position 5 with potent antiproliferative activity in non-Hodgkin lymphoma cell lines. The most potent derivative 4.35 also displayed activities across more than 60 cancer cell lines. The kinase profiling confirmed high selectivity of 4.35 toward cyclin-dependent kinases (CDKs) 2, 5, and 9, and the cocrystal with CDK2/cyclin A2 revealed its binding in the active site. Cultured lymphoma cell lines treated with 4.35 showed dephosphorylation of CDK substrates, cleavage of PARP-1, downregulation of XIAP and MCL-1, and activation of caspases, which collectively confirmed ongoing apoptosis. Moreover, 4.35 demonstrated significant activity in various cell line xenograft and patient-derived xenograft mouse models in vivo both as a monotherapy and as a combination therapy with the BCL2-targeting venetoclax. These findings support further studies of combinatorial treatment based on CDK inhibitors.