BIBU 1361 dihydrochloride

BIBU 1361 dihydrochloride is a selective inhibitor of epidermal growth factor receptor (EGFR) kinase with an IC50 value of 0.038 ± 0.007 μM [1, 2].

The EGFR signaling pathway is associated with multiple intracellular signaling events that promote proliferation and survival. It plays a key role in the progression of glioblastoma multiforme (GBM) [2].

In glioma cells, EGFR signaling can induce the phosphorylation of Akt, Erk1/2 and STAT3. BIBU 1361 decreased levels of EGFR and subsequently decreased levels of p-EGFR. This effect was accompanied by the decrease in pAkt and the downstream target p-mTOR. P-S6 kinase and p-P70S6 kinase are two key targets of p-mTOR. Both of them are associated with cell proliferation. In glioma cells treated with BIBU 1361, P-S6 kinase and p-P70S6 kinase were also downregulated. E2F1 is a G1/S regulator. E2F1 is known to be interacted with by EGFR. The inhibition of Akt/mTOR signaling can affect cell cycle progression. In glioma cells, BIBU 1361 inhibited the expression of Akt/mTOR and decreased EGFR. In glioma cells, BIBU 1361 decreased the expression of cyclin E and E2F1, increased the level of p21, and increased cell number at the S and G2/M phase of the cell cycle [2].

The effect of BIBU 1361 in the animal body has not been found.

References:
[1].  Antczak C, Mahida JP, Bhinder B, et al. A High-Content Biosensor-Based Screen Identifies Cell-Permeable Activators and Inhibitors of EGFR Function Implications in Drug Discovery. Journal of biomolecular screening, 2012, 17(7): 885-899.
[2].  Ghildiyal R, Dixit D, Sen E. EGFR inhibitor BIBU induces apoptosis and defective autophagy in glioma cells. Molecular carcinogenesis, 2013, 52(12): 970-982.

Inhibition of epidermal growth factor receptor activity by two pyrimidopyrimidine derivatives.[Pubmed:15199094]

J Pharmacol Exp Ther. 2004 Nov;311(2):502-9.

Overexpression of the epidermal growth factor receptors (EGFRs) and human epidermal growth factor receptor 2 occurs frequently in human cancers and is associated with aggressive tumor behavior and poor patient prognosis. We have investigated the effects in vitro and in vivo of a new class of inhibitor molecules on the growth of several human cancer cell lines. BIBX1382 [N8-(3-chloro-4-fluoro-phenyl)-N2-(1-methyl-piperidin-4-yl)-pyrimido[5,4-d]pyrimi dine-2,8-diamine] and BIBU1361 [(3-chloro-4-fluoro-phenyl)-[6-(4-diethylaminomethyl-piperidin-1yl)-pyrimido[5,4- d]pyrimidin-4-yl]-amine] are two new selective EGFR kinase inhibitors that do not block the activity of other tyrosine kinases. BIBU1361 blocked epidermal growth factor-induced phosphorylation of EGFR and also prevented downstream responses such as mitogen-activated protein kinase kinase (MAPK/extracellular signal-regulated kinase kinase) and MAPK activation in cells. In accordance with these observations thymidine incorporation into EGFR-expressing KB cells was selectively and potently inhibited by BIBX1382 and BIBU1361 with half-maximally effective doses in the nanomolar range. Oral administration of these compounds inhibited the growth of established human xenografts in athymic mice, including vulval and head and neck squamous cell carcinomas. Tumor growth inhibition by BIBX1382 coincided with reduced pEGFR and Ki-67 levels in vivo, which is in accordance with the expected effect of EGFR inhibitors. Collectively, these results show that the structural class of pyrimidopyrimidines, exemplified here by BIBX1382 and BIBU1361, represents an interesting scaffold for the design of EGFR inhibitors.