BKM120(NVP-BKM120, Buparlisib) is a selective PI3K inhibitor of p110α/β/δ/γ with IC50 of 52 nM/166 nM/116 nM/262 nM, respectively.
The intracellular phosphatidylinositol-3-kinase(PI3K) pathway regulates cellular functions incuding cell proliferation, growth, survival, apoptosis, protein synthesis, and glucose metabolism. BKM120, a biologic characterization of the 2-morpholino pyrimidine derivative, is a pan-PI3K inhibitor.
In vitro: NVP-BKM120 inhibits all four class I PI3K isoforms in biochemical assays with at least 50-fold selectivity against other protein kinases. NVP-BKM120 is also active against the most common somatic PI3Ka mutations but does not significantly inhibit the related class III (Vps34) and class IV (mTOR, DNA-PK) PI3K kinases. Consistent with its mechanism of action, NVP-BKM120 decreases the cellular p-Akt levels in mechanistic models and relevant tumor cell lines. In a panel of 353 cell lines test, NVP-BKM120 showed preferential inhibition of tumor cells with PIK3CA mutations, rather than either KRAS or PTEN mutant models [1].
In vivo: NVP-BKM120 shows dose-dependent in vivo pharmacodynamic activity as measured by significant inhibition of p-Akt and tumor growth inhibition in mechanistic xenograft models. In addition, NVP-BKM120 behaves synergistically when combined with either targeted agents such as MEK or HER2 inhibitors or with cytotoxic agents such as docetaxel or temozolomide [1].
Clinical trial: A phase I dose-escalation study investigated the maximum-tolerated dose (MTD), safety, preliminary activity, PK, and PD of BKM120. This study demonstrates feasibility and proof-of-concept of class I PI3K inhibition in cancer patients. BKM120 at the MTD of 100 mg d-1 is safe and well tolerated, with a good PK profile, clear evidence of target inhibition, and preliminary antitumor activity [2].
References:
[1] Maira SM, Pecchi S, Huang A, Burger M, Knapp M, Sterker D, Schnell C, Guthy D, Nagel T, Wiesmann M, Brachmann S, Fritsch C, Dorsch M, Chène P, Shoemaker K, De Pover A, Menezes D, Martiny-Baron G, Fabbro D, Wilson CJ, Schlegel R, Hofmann F, García-Echeverría C, Sellers WR, Voliva CF. Identification and characterization of NVP-BKM120, an orally available pan-class I PI3-kinase inhibitor. Mol Cancer Ther. 2012;11(2):317-28.
[2] Bendell JC, Rodon J, Burris HA, de Jonge M, Verweij J, Birle D, Demanse D, De Buck SS, Ru QC, Peters M, Goldbrunner M, Baselga J. Phase I, dose-escalation study of BKM120, an oral pan-Class I PI3K inhibitor, in patients with advanced solid tumors. J Clin Oncol. 2012;30(3):282-90.