Motesanib Diphosphate (AMG-706)

Motesanib Diphosphate is a diphosphate form of motesanib. It is a potent ATP-competitive inhibitor of VEGFR1/2/3 with IC50 of 2 nM/3 nM/6 nM, respectively [1].

Vascular endothelial growth factor (VEGF) is an important signaling protein involved in both vasculogenesis (the formation of the circulatory system) and angiogenesis (the growth of blood vessels from pre-existing vasculature). Motesanib (AMG 706) is an orally administered small molecule belonging to angiokinase inhibitor class which acts as an antagonist of VEGF receptors, platelet-derived growth factor receptors, and stem cell factor receptors.

In vitro: Motesanib diphosphate has broad activity against the human VEGFR family, and displays >1000 selectivity against EGFR, Src, and p38 kinase. Motesanib Diphosphate significantly inhibits VEGF-induced cellular proliferation of HUVECs with an IC50 of 10 nM, while displaying little effect at bFGF-induced proliferation with an IC50 of >3,000 nM. Motesanib Diphosphate also potently inhibits PDGF-induced proliferation and SCF-induced c-kit phosphorylation with IC50 of 207 nM and 37 nM, respectively, but not effective against the EGF-induced EGFR phosphorylation and cell viability of A431 cells [1]. Althouth displaying little antiproliferative activity on cell growth of HUVECs alone, Motesanib diphosphate treatment significantly sensitizes the cells to fractionated radiation [2]. 

In vivo: Oral administration of AMG 706 potently inhibited VEGF-induced angiogenesis in the rat corneal model and induced regression of established A431 xenografts. AMG 706 was well tolerated and had no significant effects o AMG 706n body weight or on the general health of the animals. Histologic analysis of tumor xenografts from AMG 706–treated animals revealed an increase in endothelial apoptosis and a reduction in blood vessel area that preceded an increase in tumor cell apoptosis. In summary, AMG 706 is an orally bioavailable, well-tolerated multikinase inhibitor that is presently under clinical investigation for the treatment of human malignancies [1]. 

Clinical trial: Motesanib was originally investigated for effectiveness against advanced nonsquamous non-small-cell lung cancer (NSCLC), with Phase II trials indicating an effectiveness comparable to bevacizumab when they were both used in combination with paclitaxel/carboplatin. However a later and more detailed Phase III trial failed to show any benefit for the treatment of NSCLC. A second Phase III trial was started in 2012, which focused on patients from Asian backgrounds (performed on the bases of subgroup analysis) however this also failed to meet its primary endpoint. The drug has undergone a Phase II evaluation as first-line therapy for breast cancer however this study found no evidence to support further investigation. Phase II testing against persistent or recurrent ovarian, fallopian tube and primary peritoneal carcinomas was also unsuccessful. There have also been 2 separate Phase II clinical trials for thyroid cancer which have both shown promising results (http://en.wikipedia.org/wiki/Motesanib). 

References:

[1] Polverino A, Coxon A, Starnes C, et al. AMG 706, an oral, multikinase inhibitor that selectively targets vascular endothelial growth factor, platelet-derived growth factor, and kit receptors, potently inhibits angiogenesis and induces regression in tumor xenografts. Cancer Res. 2006;66(17):8715-21.

[2] Kruser TJ1 Wheeler DL, Armstrong EA, Iida M, Kozak KR, van der Kogel AJ, Bussink J, Coxon A, Polverino A, Harari PM. Augmentation of radiation response by motesanib, a multikinase inhibitor that targets vascular endothelial growth factor receptors. Clin Cancer Res. 2010;16(14):3639-47.

Effect of coadministration of ketoconazole, a strong CYP3A4 inhibitor, on pharmacokinetics and tolerability of motesanib diphosphate (AMG 706) in patients with advanced solid tumors.[Pubmed:18574557]

Invest New Drugs. 2008 Oct;26(5):455-62.

Motesanib diphosphate is a novel angiogenesis inhibitor selectively targeting vascular endothelial growth factor receptors 1, 2, and 3; platelet-derived growth factor receptor and stem cell factor receptor. The purpose of this phase 1b, drug-drug interaction study was to investigate the effect of ketoconazole, a strong inhibitor of the cytochrome P450 3A4 isoenzyme, on the pharmacokinetics and tolerability of motesanib diphosphate. Fourteen patients with advanced solid tumors refractory to standard treatment were enrolled and received motesanib diphosphate 50 mg once daily from day 1 through 15. Patients were randomized to receive a single oral dose of ketoconazole 400 mg either on day 8 (Sequence 1; n = 7) or day 15 (Sequence 2; n = 7), while pharmacokinetic samples were collected. After completion of this part (day 16), 13 patients received an escalated once-daily dose of motesanib diphosphate 125 mg. Evaluable pharmacokinetic data (n = 12) suggest that ketoconazole modestly increased motesanib exposure. The motesanib area under the concentration-time curve (AUC) from 0 to 24 h increased by 86% (90% CI, 1.50-2.29; P < 0.001) and the maximum plasma concentration (C (max)) by 35% (90% CI, 1.12-1.64; P = 0.02), compared with motesanib diphosphate administration alone. The tolerability profile (with or without ketoconazole coadministration) was consistent with that from other motesanib diphosphate monotherapy studies. Treatment-related adverse events were mild to moderate and commonly included fatigue (50% of patients), hypertension (43%), diarrhea (21%), dizziness (14%), paresthesia (14%), and vomiting (14%). Hypertension was the most common related grade 3 event (21%). No grade 4 or 5 treatment-related adverse events occurred.

Motesanib Diphosphate (AMG 706 Diphosphate) is a potent ATP-competitive inhibitor of VEGFR1/2/3 with IC50s of 2 nM/3 nM/6 nM, respectively, and has similar activity against Kit, and is approximately 10-fold more selective for VEGFR than PDGFR and Ret.

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