PF-04449913

PF-04449913 is an orally bioavailable inhibitor of smoothened with IC50 value of 5nM [1].

In the Hedgehog (Hh) signaling pathway, the combination of Hh ligands and their receptor Patched leads to the activation of smoothened and subsequently activation of three transcription factors Gli1, Gli2 and Gli3. It then leads to the proliferation of cells. As an antagonist of smoothened, PF-04449913 is developed for treatment of cancer [1].

PF-04449913 is found not to inhibit cytochrome P450 and is negative in Ames and micronucleus assays suggesting it as a safe drug. In the preclinical studies, PF-04449913 shows a half-life of 30 h and an oral bioavailability of 55% in humans. It also has low plasma clearance of 1.03 mL/min/kg and moderate volume of distribution (2.7 L/kg) [1].

References:
[1] Munchhof MJ, Li Q, Shavnya A, Borzillo GV, Boyden TL, Jones CS, LaGreca SD, Martinez-Alsina L, Patel N, Pelletier K, Reiter LA, Robbins MD, Tkalcevic GT. Discovery of PF-04449913, a Potent and Orally Bioavailable Inhibitor of Smoothened. ACS Med Chem Lett. 2011 Dec 21;3(2):106-11.

The human Smoothened inhibitor PF-04449913 induces exit from quiescence and loss of multipotent Drosophila hematopoietic progenitor cells.[Pubmed:27486815]

Oncotarget. 2016 Aug 23;7(34):55313-55327.

The efficient treatment of hematological malignancies as Acute Myeloid Leukemia, myelofibrosis and Chronic Myeloid Leukemia, requires the elimination of cancer-initiating cells and the prevention of disease relapse through targeting pathways that stimulate generation and maintenance of these cells. In mammals, inhibition of Smoothened, the key mediator of the Hedgehog signaling pathway, reduces Chronic Myeloid Leukemia progression and propagation. These findings make Smo a candidate target to inhibit maintenance of leukemia-initiating cells. In Drosophila melanogaster the same pathway maintains the hematopoietic precursor cells of the lymph gland, the hematopoietic organ that develops in the larva. Using Drosophila as an in vivo model, we investigated the mode of action of PF-04449913, a small-molecule inhibitor of the human Smo protein. Drosophila larvae fed with PF-04449913 showed traits of altered hematopoietic homeostasis. These include the development of melanotic nodules, increase of circulating hemocytes, the size increase of the lymph gland and accelerated differentiation of blood cells likely due to the exit of multi-potent precursors from quiescence. Importantly, the Smo inhibition can lead to the complete loss of hematopoietic precursors. We conclude that PF-04449913 inhibits Drosophila Smo blocking the Hh signaling pathway and causing the loss of hematopoietic precursor cells. Interestingly, this is the effect expected in patients treated with PF-04449913: number decrease of cancer initiating cells in the bone marrow to reduce the risk of leukemia relapse. Altogether our results indicate that Drosophila comprises a model system for the in vivo study of molecules that target evolutionary conserved pathways implicated in human hematological malignancies.

Treatment with PF-04449913, an oral smoothened antagonist, in patients with myeloid malignancies: a phase 1 safety and pharmacokinetics study.[Pubmed:26688487]

Lancet Haematol. 2015 Aug;2(8):e339-46.

BACKGROUND: Activation of the Hedgehog signalling pathway contributes to cancer progression and the development of myeloid leukaemia stem cell therapeutic resistance. We aimed to identify the maximum tolerated dose (MTD) and the recommended phase 2 dose of the selective Hedgehog antagonist PF-04449913 in myeloid malignancies. METHODS: We undertook an open-label, dose-finding, standard 3+3 design phase 1 study of PF-04449913 in adult patients with acute myeloid leukaemia, chronic myeloid leukaemia, chronic myelomonocytic leukaemia, myelodysplastic syndrome, or myelofibrosis who were refractory, resistant, or intolerant to previous treatments, at three centres in the USA and one in Italy. Patients who had newly diagnosed, untreated disease were included if they were not eligible for standard treatment options or if standard treatments were not deemed appropriate. Patients received PF-04449913 once daily continuously until disease progression, unacceptable toxic effects, or patient withdrawal for up to 12 28-day cycles. Additional cycles were given if patients showed evidence of clinical benefit. The starting dose was 5 mg and was increased by 100% until the first dose-limiting toxic effect (DLT) and by 50% thereafter, in keeping with a 3+3 clinical trial statistical design. The primary endpoint was first-cycle DLTs. Secondary endpoints were safety, tolerability, pharmacokinetics, pharmacodynamics, and preliminary clinical activity. This trial is registered with ClinicalTrials.gov, number NCT00953758. FINDINGS: Between March 24, 2010, and Sept 7, 2012, 47 patients were enrolled and included in the study: 28 with acute myeloid leukaemia, six with myelodysplastic syndrome, five with chronic myeloid leukaemia (two with chronic-phase and three with blast-phase disease), one with chronic myelomonocytic leukaemia, and seven with myelofibrosis. Patients received PF-04449913 once daily at 5 mg (n=3), 10 mg (n=3), 20 mg (n=4), 40 mg (n=4), 80 mg (n=8), 120 mg (n=3), 180 mg (n=3), 270 mg (n=5), 400 mg (n=9), and 600 mg (n=5). Two patients experienced DLTs (one each in the 80 mg and 600 mg dose groups). The MTD for PF-04449913 was established to be 400 mg once daily. Of the 47 patients enrolled, 28 (60%) experienced treatment-related adverse events, three of which were grade 4 in severity. The most common treatment-related adverse events included dysgeusia (13 [28%] patients), decreased appetite (nine [19%]), and alopecia (seven [15%]). None of the 15 deaths reported were treatment related. Pharmacokinetics seemed to be dose proportional. The mean half-life was 23.9 h (SD 14.0) in the MTD group. Some suggestion of clinical activity was noted in 23 (49%) of 47 patients with haematological malignancies. Based on these results, the recommended phase 2 dose was 200 mg or lower once daily. INTERPRETATION: Based on these findings, PF-04449913 is being tested in phase 2 studies in patients with myelodysplastic syndrome, acute myeloid leukaemia, and myelofibrosis. FUNDING: Pfizer.

A phase I study of PF-04449913, an oral hedgehog inhibitor, in patients with advanced solid tumors.[Pubmed:25388167]

Clin Cancer Res. 2015 Mar 1;21(5):1044-51.

PURPOSE: To estimate the maximum tolerated dose (MTD) of single-agent PF-04449913, and to evaluate safety, tolerability, pharmacokinetics, pharmacodynamics, and preliminary antitumor activity in patients with advanced tumors. EXPERIMENTAL DESIGN: A 3+3 design was used in this open-label, multicenter, phase I study and dose escalation/de-escalation applied until identification of the MTD. PF-04449913 was orally administered once daily in continuous 28-day treatment cycles. The starting dose was 80 mg. RESULTS: A total of 23 patients were enrolled; 19 were evaluable for first-cycle dose-limiting toxicity (DLT). The first-cycle DLT rate at the 640 mg dose level was 33.3%, and the MTD was estimated to be 320 mg once daily. The recommended phase II dose was not determined. PF-04449913 was generally well tolerated at doses of 80 to 320 mg once daily. The most common treatment-related adverse events (AE) were grade 1-2 dysgeusia, fatigue, decreased appetite, nausea, dizziness, dehydration, and diarrhea. Treatment-related grade 3 AEs only occurred in patients receiving PF-04449913 640 mg once daily. No treatment-related grade 4-5 AEs were reported. Pharmacokinetic analysis indicated a generally dose-proportional kinetics with biphasic elimination, supporting once-daily dosing. PF-04449913 modulated hedgehog signaling at the dose levels tested, as demonstrated by >80% downregulation of GLI1 expression in the skin of treated patients. Eight patients (34.8%) achieved stable disease; none had complete or partial response. Three patients with disease progression at enrollment had prolonged disease stabilization (>/=6 months). CONCLUSIONS: The results obtained in this study support further evaluation of PF-04449913 in patients with advanced solid tumors.

Metabolism, excretion and pharmacokinetics of [(14)C]glasdegib (PF-04449913) in healthy volunteers following oral administration.[Pubmed:27866461]

Xenobiotica. 2017 Dec;47(12):1064-1076.

1. The metabolism, excretion and pharmacokinetics of glasdegib (PF-04449913) were investigated following administration of a single oral dose of 100 mg/100 muCi [(14)C]glasdegib to six healthy male volunteers (NCT02110342). 2. The peak concentrations of glasdegib (890.3 ng/mL) and total radioactivity (1043 ngEq/mL) occurred in plasma at 0.75 hours post-dose. The AUCinf were 8469 ng.h/mL and 12,230 ngEq.h/mL respectively, for glasdegib and total radioactivity. 3. Mean recovery of [(14)C]glasdegib-related radioactivity in excreta was 91% of the administered dose (49% in urine and 42% in feces). Glasdegib was the major circulating component accounting for 69% of the total radioactivity in plasma. An N-desmethyl metabolite and an N-glucuronide metabolite of glasdegib represented 8% and 7% of the circulating radioactivity, respectively. Glasdegib was the major excreted component in urine and feces, accounting for 17% and 20% of administered dose in the 0-120 hour pooled samples, respectively. Other metabolites with abundance <3% of the total circulating radioactivity or dose in plasma or excreta were hydroxyl metabolites, a desaturation metabolite, N-oxidation and O-glucuronide metabolites. 4. Elimination of [(14)C]glasdegib-derived radioactivity was essentially complete, with similar contribution from urinary and fecal routes. Oxidative metabolism appears to play a significant role in the biotransformation of glasdegib.

Glasdegib (PF-04449913) is a potent and orally bioavailable smoothened inhibitor. Glasdegib (PF-04449913) binds to human SMO (amino acids 181-787) with an IC50 of 4 nM.

PF-04449913,1095173-27-5,Glasdegib,Natural Products,Smoothened, buy PF-04449913 , PF-04449913 supplier , purchase PF-04449913 , PF-04449913 cost , PF-04449913 manufacturer , order PF-04449913 , high purity PF-04449913