Dual Inhibition of Bruton's Tyrosine Kinase and Phosphoinositide-3-Kinase p110δ as a Therapeutic Approach to Treat Non-Hodgkin's B Cell Malignancies.

Although new targeted therapies, such as ibrutinib and idelalisib, have made a large impact on non-Hodgkin's lymphoma (NHL) patients, the disease is often fatal because patients are initially resistant to these targeted therapies, or because they eventually develop resistance. New drugs and treatments are necessary for these patients. One attractive approach is to inhibit multiple parallel pathways that drive the growth of these hematologic tumors, possibly prolonging the duration of the response and reducing resistance. Early clinical trials have tested this approach by dosing two drugs in combination in NHL patients. We discovered a single molecule, MDVN1003 (1-(5-amino-2,3-dihydro-1H-inden-2-yl)-3-(8-fluoro-3,4-dihydro-2H-benzo[b][1,4]oxazin-6-yl)-1H-pyrazolo[3,4-d]pyrimidin-4-amine), that inhibits Bruton's tyrosine kinase and phosphatidylinositol-3-kinase δ, two proteins regulated by the B cell receptor that drive the growth of many NHLs. In this report, we show that this dual inhibitor prevents the activation of B cells and inhibits the phosphorylation of protein kinase B and extracellular signal-regulated kinase 1/2, two downstream mediators that are important for this process. Additionally, MDVN1003 induces cell death in a B cell lymphoma cell line but not in an irrelevant erythroblast cell line. Importantly, we found that this orally bioavailable dual inhibitor reduced tumor growth in a B cell lymphoma xenograft model more effectively than either ibrutinib or idelalisib. Taken together, these results suggest that dual inhibition of these two key pathways by a single molecule could be a viable approach for treatment of NHL patients.

Discovery of Pyrazolopyrimidine Derivatives as Novel Dual Inhibitors of BTK and PI3Kδ.

The aberrant activation of B-cells has been implicated in several types of cancers and hematological disorders. BTK and PI3Kδ are kinases responsible for B-cell signal transduction, and inhibitors of these enzymes have demonstrated clinical benefit in certain types of lymphoma. Simultaneous inhibition of these pathways could result in more robust responses or overcome resistance as observed in single agent use. We report a series of novel compounds that have low nanomolar potency against both BTK and PI3Kδ as well as acceptable PK properties that could be useful in the development of treatments against B-cell related diseases.