Plasma protein binding of the investigational anticancer agent 2-methoxyestradiol

PEGylated Polymeric Nanoparticles Loaded with 2-Methoxyestradiol for the Treatment of Uterine Leiomyoma in a Patient-Derived Xenograft Mouse Model

Leiomyomas, the most common benign neoplasms of the female reproductive tract, currently have limited medical treatment options. Drugs targeting estrogen/progesterone signaling are used, but side effects and limited efficacy in many cases are major limitation of their clinical use. Previous studies from our laboratory and others demonstrated that 2-methoxyestradiol (2-ME) is promising treatment for uterine fibroids. However, its poor bioavailability and rapid degradation hinder its development for clinical use. The objective of this study is to evaluate the in vivo effect of biodegradable and biocompatible 2-ME-loaded polymeric nanoparticles in a patient-derived leiomyoma xenograft mouse model. PEGylated poly(lactide-co-glycolide) (PEG-PLGA) nanoparticles loaded with 2-ME were prepared by nanoprecipitation. Female 6-week age immunodeficient NOG (NOD/Shi-scid/IL-2Rγnull) mice were used. Estrogen-progesterone pellets were implanted subcutaneously. Five days later, patient-derived human fibroid tumors were xenografted bilaterally subcutaneously. Engrafted mice were treated with 2-ME-loaded or blank (control) PEGylated nanoparticles. Nanoparticles were injected intraperitoneally and after 28 days of treatment, tumor volume was measured by caliper following hair removal, and tumors were removed and weighed. Up to 99.1% encapsulation efficiency was achieved, and the in vitro release profile showed minimal burst release, thus confirming the high encapsulation efficiency. In vivo administration of the 2-ME-loaded nanoparticles led to 51% growth inhibition of xenografted tumors compared to controls (P < 0.01). Thus, 2-ME-loaded nanoparticles may represent a novel approach for the treatment of uterine fibroids.

Recent Advances in chemistry and pharmacology of 2-methoxyestradiol: An anticancer investigational drug

2-Methoxyestradiol (2ME2), an estrogen hormone metabolite is a potential cancer chemotherapeutic agent. Presently, it is an investigational drug under various phases of clinical trials alone or in combination therapy. Its anticancer activity has been attributed to its antitubulin, antiangiogenic, pro-apoptotic and ROS induction properties. This anticancer drug candidate has been explored extensively in last twenty years for its detailed chemistry and pharmacology. Present review is an update of its chemistry and biological activity. It also extends an assessment of potential of 2ME2 and its analogues as possible anticancer drug in future.

Preclinical disposition (in vitro) of novel μ-opioid receptor selective antagonists

Recently, two novel N-heterocyclic derivatives of naltrexone [designated 17-cyclopropylmethyl-3,14β-dihydroxy-4,5α-epoxy-6β-[(4'-pyridyl)acetamido]morphinan (NAP) and 17-cyclopropylmethyl-3,14β-dihydroxy-4,5α-epoxy-6α-[(3'-isoquinolyl) acetamido]morphinan (NAQ)] have been proposed as μ-opioid receptor (MOR) selective antagonists. The goal of this study was to examine their absorption and metabolism. The bidirectional transport of NAP and NAQ was determined in Caco-2 and MDCKII-MDR1 cells, and the permeability directional ratio (PDR) was estimated (PDR = P(app, B-A)/P(app, A-B), where P(app) is the apparent permeability, A is apical, and B is basolateral). Oxidative metabolism of NAQ (0.5-80 μM) and NAP (0.5-30 μM) was determined in pooled human liver microsomes. The reaction monitored the disappearance of NAQ/NAP. NAP and NAQ were quantitated by high-performance liquid chromatography-UV at 270 or 232 nm, respectively. The permeability of NAQ or NAP was similar to that of naltrexone or paracellular markers, respectively. NAP also exhibited a high PDR and was determined to be a P-glycoprotein (P-gp) substrate. Unbound fractions in human plasma for NAQ and NAP were 0.026 ± 0.019 and 0.85 ± 0.12, respectively. The metabolic oxidative reaction rates, fitted to a Michaelis-Menten model, yielded K(m) and V(max) values of 15.8 ± 5.5 μM and 192 ± 24 pmol/min for NAQ and 1.8 ± 1.5 μM and 8.1 ± 1.4 pmol/min for NAP. Intrinsic hepatic clearance was estimated to be 13 and 5 ml · min(-1) · kg(-1) for NAQ and NAP, respectively. Neither NAQ nor NAP underwent detectable glucuronidation. Thus, NAP was a P-gp substrate with low apparent permeability, whereas NAQ was not a P-gp substrate and showed better permeability. Therefore, in contrast to NAP, NAQ would be more suitable for oral absorption and penetration of the blood-brain barrier, yielding potential pharmacokinetic and pharmacodynamic advantages over naltrexone.

Therapeutic promises of 2-methoxyestradiol and its drug disposition challenges

2-Methoxyestradiol (2MeO-E2) is an endogenous metabolite of estrogen which was initially considered to be inactive. During the last few decades it has been shown that 2MeO-E2 is a promising anticancer drug. In vitro experiments have demonstrated that it has several anticancer activities, and potential to alleviate hypertension, glomerulosclerosis, hypercholesterolemia, and other disorders. However, due to its low solubility and extensive glucuronidation, to achieve effective concentrations large doses of 2MeO-E2 would be required. Clinical studies reflected very high inter- and intrapatient variability and oral bioavailability of 1 to 2%. Thus, this review paper highlights the origin of this compound, its therapeutic promises, and possible mechanisms of action. It also discusses the pharmacokinetic properties of 2MeO-E2 as well as current developments to overcome low drug solubility and its extensive first pass metabolism.

Correlation of 2-methoxyestradiol levels in cord blood and complications of prematurity

2-methoxyestradiol (2ME2) is a potent antiangiogenic molecule that inhibits the expression of hypoxia-inducible factor (HIF)-1alpha and, consequently, of VEGF and other HIF-1alpha target genes. Although 2ME2 is elevated during pregnancy in maternal serum, its presence in fetal fluids and its impact in neonatal health are unknown. In this study, we 1) described normal levels of 2ME2 in maternal blood, cord blood, breast milk, and amniotic fluid, and 2) compared a composite measure of perinatal outcome between infants born with high and low levels of 2ME2. We found that 2ME2 was significantly decreased in all fluids compared with prepartum maternal serum. After stratifying babies by 2ME2 exposure levels, we observed no differences in the vulnerability to impaired lung development or to complications involving aberrant angiogenesis or vascular leak, such as necrotizing enterocolitis (NEC), intraventricular hemorrhage (IVH), posthemorrhagic hydrocephalus (PHH), and retinopathy of prematurity (ROP). In summary, fetal 2ME2 concentrations do not appear to affect neonatal outcome.

Characterization of in vitro and in vivo metabolic pathways of the investigational anticancer agent, 2-methoxyestradiol

The aim of this study was to characterize the metabolic pathways of 2-methoxyestradiol (2ME2), an investigational anticancer drug. In vitro metabolism studies were performed by incubation of 2ME2 with human liver microsomes under various conditions and metabolite identification was performed using liquid chromatography-tandem mass spectrometry. In microsomal mixtures, four major oxidative metabolites and two glucuronic acid conjugates were observed originating from 2ME2. Human liver S9 protein fraction was used to screen for in vitro sulfation but no prominent conjugates were observed. The total hepatic clearance as estimated using the well-stirred model was approximately 712 mL/min. In vivo metabolism, assessed using 24-h collections of urine from cancer patients treated with 2ME2 revealed that <0.01% of the total administered dose of 2ME2 is excreted unchanged in urine and about 1% excreted as glucuronides. Collectively, this suggests that glucuronidation and subsequent urinary excretion are elimination pathways for 2ME2.

Multiple effects of 2ME2 and D609 on the cortical expression of HIF-1alpha and apoptotic genes in a middle cerebral artery occlusion-induced focal ischemia rat model

Despite 2-methoxyestradiol (2ME2) and tricyclodecan-9-yl-xanthogenate (D609) having multiple effects on cancer cells, mechanistically, both of them down-regulate hypoxia-inducible factor-1alpha (HIF-1alpha) and vascular endothelial growth factor (VEGF). We hypothesize HIF-1alpha plays an essential role in cerebral ischemia as a pro-apoptosis regulator; 2ME2 and D609 decrease the levels of HIF-1alpha and VEGF, that might contribute to protecting brain from ischemia injury. A total of 102 male Sprague-Dawley rats were split into five groups: sham, middle cerebral artery occlusion (MCAO), MCAO + dimethyl sulfoxide, MCAO + 2ME2, and MCAO + D609. 2ME2 and D609 were injected intraperitoneally 1 h after reperfusion. Rats were killed at 24 h and 7 days. At 24 h, 2ME2 and D609 reduce the levels of HIF-1alpha and VEGF (enzyme-linked immunosorbent assay), depress the expression of HIF-1alpha, VEGF, BCL2/adenovirus E1B 19 kDa interacting protein 3 (BNIP3) and cleaved caspase 3 (western blot and immunohistochemistry) in the brain infarct area. Double fluorescence labeling shows HIF-1alpha positive immunoreactive materials are co-localized with BNIP3 and terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling inside the nuclei of neurons. At 7 days, 2ME2 and D609 reduce the infarct volume (2,3,7-triphenyltetrazolium chloride) and blood-brain barrier extravasation, decrease the mortality and improve the neurological deficits. In conclusion, 2ME2 and D609 are powerful agents to protect brain from cerebral ischemic injury by inhibiting HIF-1alpha expression, attenuating the superfluous expression of VEGF to avoid blood-brain barrier disruption and suppressing neuronal apoptosis via BNIP3 pathway.