Design and synthesis of novel 1-substituted 3-(6-phenoxypyridin-3-yl)-1H-pyrazolo[3,4-d]pyrimidin-4-amine analogs as selective BTK inhibitors for the treatment of mantle cell lymphoma

Ibrutinib (IBN), a first-in-class BTK-inhibitor, was approved by the FDA for the treatment of mantle cell lymphoma (MCL). Although IBN shows excellent performance as an anti-lymphoma agent, it has some undesirable side effects due to its off-target activities. Our studies yielded a novel series of 3-(6-phenoxypyridin-3-yl)-4-amine-1H-pyrazolo[3,4-d]pyrimidine derivatives capable of potent inhibition of Bruton's tyrosine kinase (BTK). Notably, compound 13e explained potent BTK inhibitory activity and could completely inhibit the phosphorylation of BTK and PLCγ2 in Z138 cells at low micromolar concentration. Compared with IBN, compound 13e improved anti-proliferative activities 3–40 folds in MCL cell lines with IC₅₀ values lower than 1 μM. Low micromolar doses of 13e could induce strong cell apoptosis in Jeko-1 and Z138 cells. In addition, compound 13e showed greater BTK selectivity and higher stability in human liver microsomes than IBN and potential safety improvement for the treatment of MCL.