PF-3084014

Biochem/physiol Actions

PF-03084014 inhibits the Notch signalling pathway. It contributes totumor suppression in breast, pancreatic carcinoma, hepatocellular carcinoma and progressive desmoid tumors. PF-03084014 in combination with dexamethasone elicits antileukemic effects in T-cell acute lymphoblastic leukemias (T-ALL).

Enzyme inhibitor

This novelγ-secretase inhibitor (FW = 489.66 g/mol; CAS 1290543-63-3; soluble in DMSO), also code-named HY-15185 and systematically named [(S)-2-((S)-5,7-difluoro-1,2,3,4-tetrahydronaphthalen-3-ylamino)-N-(1-(2- methyl-1-(neopentylamino)propan-2-yl)-1H-imidazol-4-yl)pentanamide], inhibitsγ-secretase reversibly, noncompetitively, and selectively, thereby reducing amyloid-b (Ab) production, with an in vitro IC50 of 1.2 nM in a whole-cell assay and 6.2 nM in cell-free assay. PF-03084014 inhibits Notch-related T- and B-cell maturation in an in vitro thymocyte assay with an EC50 of 2.1 μM. PF-3084014 had an IC50 on B- and T-cell reductions of 1.3 to 3 μM with a mean EC50 of 2.1 μM. This represents >300-fold separation from the broken-cell Aβ IC50 and >1500x separation from the whole-cell IC50. A single acute dose showed dose-dependent reduction in brain, cerebrospinal fluid (CSF), and plasma Ab . When dosed with PF- 3084014 for 5 days using an osmotic minipump (0.03 to 3 mg/kg/day), Guinea pigs exhibited dose-dependent Ab reduction in brain, CSF, and plasma. While otherγ-secretase inhibitors show high potency at elevating Ab in the conditioned media of whole cells and the plasma of multiple animal models and humans, such potentiation is not observed with PF- 3084014. By evoking antitumor and antimetastatic properties via pleiotropic mechanisms, experiments with PF-03084014 offer hope that Notch pathway downstream genes may be used to predict the antitumor activity of PF-03084014 in breast cancer patients.