Pharmacologic activation of estrogen receptor ß increases mitochondrial function, energy expenditure, and brown adipose tissue.

Most satiety-inducing obesity therapeutics, despite modest efficacy, have safety concerns that underscore the need for effective peripherally acting drugs. An attractive therapeutic approach for obesity is to optimize/maximize energy expenditure by increasing energy-utilizing thermogenic brown adipose tissue. We used in vivo and in vitro models to determine the role of estrogen receptor ß (ER-ß) and its ligands on adipose biology. RNA sequencing and metabolomics were used to determine the mechanism of action of ER-ß and its ligands. Estrogen receptor ß (ER-ß) and its selective ligand reprogrammed preadipocytes and precursor stem cells into brown adipose tissue and increased mitochondrial respiration. An ER-ß-selective ligand increased markers of tricarboxylic acid-dependent and -independent energy biogenesis and oxygen consumption in mice without a concomitant increase in physical activity or food consumption, all culminating in significantly reduced weight gain and adiposity. The antiobesity effects of ER-ß ligand were not observed in ER-ß-knockout mice. Serum metabolite profiles of adult lean and juvenile mice were comparable, while that of adult obese mice was distinct, indicating a possible impact of obesity on age-dependent metabolism. This phenotype was partially reversed by ER-ß-selective ligand. These data highlight a new role for ER-ß in adipose biology and its potential to be a safer alternative peripheral therapeutic target for obesity.-Ponnusamy, S., Tran, Q. T., Harvey, I., Smallwood, H. S., Thiyagarajan, T., Banerjee, S., Johnson, D. L., Dalton, J. T., Sullivan, R. D., Miller, D. D., Bridges, D., Narayanan, R. Pharmacologic activation of estrogen receptor ß increases mitochondrial function, energy expenditure, and brown adipose tissue.

The long and winding road for selective androgen receptor modulators.

Numerous selective androgen receptor modulators (SARMs) with differing chemical structures and nearly ideal pharmacological and pharmacokinetic properties have been developed that are well tolerated and selectively increase lean body mass in humans. However, definitive demonstration of the linkage between lean body mass and physical function in a relevant, large patient population has remained elusive for a SARM. The clinical endpoints serving as their basis of approval have shifted with time and clinical indication and are likely to continue to do so as the field matures with additional safety and efficacy data pertaining to the relationship between lean body mass and physical function, regulatory decisions with SARMs and other agents, and yet unexplored clinical indications.

Pharmacokinetic drug interactions of the selective androgen receptor modulator GTx-024(Enobosarm) with itraconazole, rifampin, probenecid, celecoxib and rosuvastatin.

GTx-024 (also known as enobosarm) is a first in class selective androgen receptor modulator being developed for diverse indications in oncology. Preclinical studies of GTx-024 supported the evaluation of several potential drug-drug interactions in a clinical setting. A series of open-label Phase I GTx-024 drug-drug interaction studies were designed to interrogate potential interactions with CYP3A4 inhibitor (itraconazole), a CYP3A4 inducer (rifampin), a pan-UGT inhibitor (probenecid), a CYP2C9 substrate (celecoxib) and a BCRP substrate (rosuvastatin). The plasma pharmacokinetics of GTx-024, its major metabolite (GTx-024 glucuronide), and each substrate were characterized in detail. Itraconazole administration had no effect on GTx-024 pharmacokinetics. Likewise, GTx-024 administration did not significantly change the pharmacokinetics of celecoxib or rosuvastatin. Rifampin administration had the largest impact on GTx-024 pharmacokinetics of any co-administered agent and reduced the maximal plasma concentration (Cmax) by 23 % and the area under the curve (AUC∞) by 43 %. Probenecid had a complex interaction with GTx-024 whereby both GTx-024 plasma levels and GTx-024 glucuronide plasma levels (AUC∞) were increased by co-administration of the UGT inhibitor (50 and 112 %, respectively). Overall, GTx-024 was well tolerated and poses very little risk of generating clinically relevant drug-drug interactions.

Study Design and Rationale for the Phase 3 Clinical Development Program of Enobosarm, a Selective Androgen Receptor Modulator, for the Prevention and Treatment of Muscle Wasting in Cancer Patients (POWER Trials).

Muscle wasting in cancer is a common and often occult condition that can occur prior to overt signs of weight loss and before a clinical diagnosis of cachexia can be made. Muscle wasting in cancer is an important and independent predictor of progressive functional impairment, decreased quality of life, and increased mortality. Although several therapeutic agents are currently in development for the treatment of muscle wasting or cachexia in cancer, the majority of these agents do not directly inhibit muscle loss. Selective androgen receptor modulators (SARMs) have the potential to increase lean body mass (LBM) and hence muscle mass, without the untoward side effects seen with traditional anabolic agents. Enobosarm, a nonsteroidal SARM, is an agent in clinical development for prevention and treatment of muscle wasting in patients with cancer (POWER 1 and 2 trials). The POWER trials are two identically designed randomized, double-blind, placebo-controlled, multicenter, and multinational phase 3 trials to assess the efficacy of enobosarm for the prevention and treatment of muscle wasting in subjects initiating first-line chemotherapy for non-small-cell lung cancer (NSCLC). To assess enobosarm's effect on both prevention and treatment of muscle wasting, no minimum weight loss is required. These pivotal trials have pioneered the methodological and regulatory fields exploring a therapeutic agent for cancer-associated muscle wasting, a process hereby described. In each POWER trial, subjects will receive placebo (n = 150) or enobosarm 3 mg (n = 150) orally once daily for 147 days. Physical function, assessed as stair climb power (SCP), and LBM, assessed by dual-energy X-ray absorptiometry (DXA), are the co-primary efficacy endpoints in both trials assessed at day 84. Based on extensive feedback from the US Food and Drug Administration (FDA), the co-primary endpoints will be analyzed as a responder analysis. To be considered a physical function responder, a subject must have ≥10 % improvement in physical function compared to baseline. To meet the definition of response on LBM, a subject must have demonstrated no loss of LBM compared with baseline. Secondary endpoints include durability of response assessed at day 147 in those responding at day 84. A combined overall survival analysis for both studies is considered a key secondary safety endpoint. The POWER trials design was established with extensive clinical input and collaboration with regulatory agencies. The efficacy endpoints are a result of this feedback and discussion of the threshold for clinical benefit in patients at risk for muscle wasting. Full results from these studies will soon be published and will further guide the development of future anabolic trials. Clinical Trial ID: NCT01355484. https://clinicaltrials.gov/ct2/show/NCT01355484 , NCT01355497. https://clinicaltrials.gov/ct2/show/NCT01355497?term=g300505&rank=1 .

Effects of enobosarm on muscle wasting and physical function in patients with cancer: a double-blind, randomised controlled phase 2 trial.

BACKGROUND: Cancer-induced muscle wasting begins early in the course of a patient's malignant disease, resulting in declining physical function and other detrimental clinical consequences. This randomised, double-blind, placebo-controlled phase 2 trial assessed the efficacy and safety of enobosarm, a selective androgen receptor modulator, in patients with cancer. METHODS: We enrolled male (>45 years) and female (postmenopausal) patients with cancer who were not obese and who had at least 2% weight loss in the previous 6 months. Participants were randomly assigned (1:1:1 ratio, by computer generated list, block size three, stratified by cancer type) to receive once-daily oral enobosarm 1 mg, 3 mg, or placebo for up to 113 days at US and Argentinian oncology clinics. The sponsor, study personnel, and participants were masked to assignment. The primary endpoint was change in total lean body mass from baseline, assessed by dual-energy x-ray absorptiometry. Efficacy analyses were done only in patients who had a baseline and an on-treatment assessment in the protocol-specified window of within 10 days before baseline or first study drug, and within 10 days of day 113 or end of study (evaluable efficacy population). Adverse events and other safety measurements were assessed in the intention-to-treat (safety) population. This trial is registered with ClinicalTrials.gov, number NCT00467844. FINDINGS: Enrolment started on July 3, 2007, and the last patient completed the trial on Aug 1, 2008. 159 patients were analysed for safety (placebo, n=52; enobosarm 1 mg, n=53; enobosarm 3 mg, n=54). The evaluable efficacy population included 100 participants (placebo, n=34; enobosarm 1 mg, n=32; enobosarm 3 mg, n=34). Compared with baseline, significant increases in total lean body mass by day 113 or end of study were noted in both enobosarm groups (enobosarm 1 mg median 1·5 kg, range -2·1 to 12·6, p=0·0012; enodosarm 3 mg 1·0 kg, -4·8 to 11·5, p=0·046). Change in total lean body mass within the placebo group (median 0·02 kg, range -5·8 to 6·7) was not significant (p=0·88). The most common serious adverse events were malignant neoplasm progression (eight of 52 [15%] with placebo vs five of 53 [9%] with enobosarm 1 mg vs seven of 54 [13%] with enobosarm 3 mg), pneumonia (two [4%] vs two [4%] vs three [6%]), and febrile neutropenia (three [6%vs one [2%] vs none). None of these events were deemed related to study drug. INTERPRETATION: Cancer cachexia is an unmet medical need and our data suggest that use of enobosarm might lead to improvements in lean body mass, without the toxic effects associated with androgens and progestational agents. FUNDING: GTx.

Role and pharmacologic significance of cytochrome P-450 2D6 in oxidative metabolism of toremifene and tamoxifen.

We investigated the in vitro metabolism and estrogenic and antiestrogenic activity of toremifene (TOR), tamoxifen (TAM) and their metabolites to better understand the potential effects of cytochrome P-450 2D6 (CYP2D6) status on the activity of these drugs in women with breast cancer. The plasma concentrations of TOR and its N-desmethyl (NDM) and 4-hydroxy (4-OH) metabolites during steady-state dosing with TOR were also determined. Unlike TOR, TAM and its NDM metabolite were extensively oxidized to 4-OH TAM and 4-OH-NDM TAM by CYP2D6, and the rate of metabolism was affected by CYP2D6 status. 4-OH-NDM TOR concentrations were not measurable at steady state in plasma of subjects taking 80 mg of TOR. Molecular modeling provided insight into the lack of 4-hydroxylation of TOR by CYP2D6. The 4-OH and 4-OH-NDM metabolites of TOR and TAM bound to estrogen receptor (ER) subtypes with fourfold to 30-fold greater affinity were 35- to 187-fold more efficient at antagonizing ER transactivation and had antiestrogenic potency that was up to 360-fold greater than their parent drugs. Our findings suggest that variations in CYP2D6 metabolic capacity may cause significant differences in plasma concentrations of active TAM metabolites (i.e., 4-OH TAM and 4-OH-NDM TAM) and contribute to variable pharmacologic activity. Unlike TAM, the clinical benefits in subjects taking TOR to treat metastatic breast cancer would not likely be subject to allelic variation in CYP2D6 status or affected by coadministration of CYP2D6-inhibiting medications.

Muscle wasting in cancer cachexia: clinical implications, diagnosis, and emerging treatment strategies.

Cancer cachexia is a complex metabolic condition characterized by loss of skeletal muscle. Common clinical manifestations include muscle wasting, anemia, reduced caloric intake, and altered immune function, which contribute to increased disability, fatigue, diminished quality of life, and reduced survival. The prevalence of cachexia and the impact of this disorder on the patient and family underscore the need for effective management strategies. Dietary supplementation and appetite stimulation alone are inadequate to reverse the underlying metabolic abnormalities of cancer cachexia and have limited long-term impact on patient quality of life and survival. Therapies that can increase muscle mass and physical performance may be a promising option; however, there are currently no drugs approved for the prevention or treatment of cancer cachexia. Several agents are in clinical development, including anabolic agents, such as selective androgen receptor modulators and drugs targeting inflammatory cytokines that promote skeletal muscle catabolism.

Role of nuclear receptors in lipid dysfunction and obesity-related diseases.

This article is a report on a symposium sponsored by the American Society for Pharmacology and Experimental Therapeutics and held at the Experimental Biology 12 meeting in San Diego, CA. The presentations discussed the roles of a number of nuclear receptors in regulating glucose and lipid homeostasis, the pathophysiology of obesity-related disease states, and the promise associated with targeting their activities to treat these diseases. While many of these receptors (in particular, constitutive androstane receptor and pregnane X receptor) and their target enzymes have been thought of as regulators of drug and xenobiotic metabolism, this symposium highlighted the advances made in our understanding of the endogenous functions of these receptors. Similarly, as we gain a better understanding of the mechanisms underlying bile acid signaling pathways in the regulation of body weight and glucose homeostasis, we see the importance of using complementary approaches to elucidate this fascinating network of pathways. The observation that some receptors, like the farnesoid X receptor, can function in a tissue-specific manner via well defined mechanisms has important clinical implications, particularly in the treatment of liver diseases. Finally, the novel findings that agents that selectively activate estrogen receptor ß can effectively inhibit weight gain in a high-fat diet model of obesity identifies a new role for this member of the steroid superfamily. Taken together, the significant findings reported during this symposium illustrate the promise associated with targeting a number of nuclear receptors for the development of new therapies to treat obesity and other metabolic disorders.

Absorption, distribution, metabolism and excretion of the novel SARM GTx-024 [(S)-N-(4-cyano-3-(trifluoromethyl)phenyl)-3-(4-cyanophenoxy)-2-hydroxy-2-methylpropanamide] in rats.

1. GTx-024, a novel selective androgen receptor modulator, is currently being investigated as an oral treatment for muscle wasting disorders associated with cancer and other chronic conditions. 2. Absorption of GTx-024 was rapid and complete, with high oral bioavailability. A wide tissue distribution of [(14)C]GTx-024 derived radioactivity was observed. [(14)C]GTx-024-derived radioactivity had a moderate plasma clearance (117.7 and 74.5 mL/h/kg) and mean elimination half-life of 0.6 h and 16.4 h in male and female rats, respectively. 3. Fecal excretion was the predominant route of elimination, with ∼70% of total radioactivity recovered in feces and 21-25% in urine within 48 h. Feces of intact rats contained primarily unchanged [(14)C]GTx-024 (49.3-64.6%). Metabolites were identified in urine and feces resulting from oxidation of the cyanophenol ring (M8, 17.6%), hydrolysis and/or further conjugation of the amide moiety (M3, 8-12%) and the cyanophenol ring (M4, 1.3-1.5%), and glucuronidation of [(14)C]GTx-024 at the tertiary alcohol (M6, 3.5-3.7%). There was no quantifiable metabolite in plasma. 4. In summary, in the rat GTx-024 is completely absorbed, widely distributed, biotransformed through several metabolic pathways, and eliminated in feces primarily as an unchanged drug.

Alanine aminotransferase regulation by androgens in non-hepatic tissues.

PURPOSE: Alanine amino-transferases (ALTs) play a crucial role in drug development as a surrogate marker of liver injury where elevations in serum ALT activity are used to diagnose drug-induced liver damage. Two ALT isoforms have been characterized with disparate but overlapping tissue expression. ALT1 is primarily expressed in live; ALT2 is found in muscle and prostate tissues. We investigate ALT gene expression in diverse rodent tissues following administration of the steroidal androgen receptor (AR) agonist dihydrotestosterone and a novel tissue selective nonsteroidal agonist S-23. METHODS: Putative AR regulation of ALT expression was determined in silico by an orthologous promoter androgen response element (ARE) search. Regulation was evaluated by transient transfection of ALT promoter region constructs and qRT-PCR experiments in cultured cells and in tissues following androgen administration. RESULTS: Several putative AREs were found in the proximal promoter regions of ALT1 and ALT2. AREs in ALT2 but not ALT1 were capable of AR-mediated transcription. ALT2 expression was affected by castration and androgen administration in muscle and prostate but not liver tissues. CONCLUSIONS: Androgen action in non-hepatic tissues, as opposed to xenobiotic toxicity alone, may contribute to increases in serum ALT activity following androgen administration.

Novel tubulin polymerization inhibitors overcome multidrug resistance and reduce melanoma lung metastasis.

PURPOSE: To evaluate abilities of 2-aryl-4-benzoyl-imidazoles (ABI) to overcome multidrug resistance (MDR), define their cellular target, and assess in vivo antimelanoma efficacy. METHODS: MDR cell lines that overexpressed P-glycoprotein, MDR-associated proteins, and breast cancer resistance protein were used to evaluate ABI ability to overcome MDR. Cell cycle analysis, molecular modeling, and microtubule imaging were used to define ABI cellular target. SHO mice bearing A375 human melanoma xenograft were used to evaluate ABI in vivo antitumor activity. B16-F10/C57BL mouse melanoma lung metastasis model was used to test ABI efficacy to inhibit tumor lung metastasis. RESULTS: ABIs showed similar potency to MDR cells compared to matching parent cells. ABIs were identified to target tubulin on the colchicine binding site. After 31 days of treatment, ABI-288 dosed at 25 mg/kg inhibited melanoma tumor growth by 69%; dacarbazine at 60 mg/kg inhibited growth by 52%. ABI-274 dosed at 25 mg/kg showed better lung metastasis inhibition than dacarbazine at 60 mg/kg. CONCLUSIONS: This new class of antimitotic compounds can overcome several clinically important drug resistant mechanisms in vitro and are effective in inhibiting melanoma lung metastasis in vivo, supporting their further development.

Orally bioavailable tubulin antagonists for paclitaxel-refractory cancer.

PURPOSE: To evaluate the efficacy and oral activity of two promising indoles, (2-(1H-indol-3-yl)-1H-imidazol-4-yl)(3,4,5-trimethoxyphenyl)methanone [compound II] and (2-(1H-indol-5-ylamino)-thiazol-4-yl)(3,4,5-trimethoxyphenyl)methanone [compound IAT], in paclitaxel- and docetaxel-resistant tumor models in vitro and in vivo. METHODS: The in vitro drug-like properties, including potency, solubility, metabolic stability, and drug-drug interactions were examined for our two active compounds. An in vivo pharmacokinetic study and antitumor efficacy study were also completed to compare their efficacy with docetaxel. RESULTS: Both compounds bound to the colchicine-binding site on tubulin, and inhibited tubulin polymerization, resulting in highly potent cytotoxic activity in vitro. While the potency of paclitaxel and docetaxel was compromised in a multidrug-resistant cell line that overexpresses P-glycoprotein, the potency of compounds II and IAT was maintained. Both compounds had favorable drug-like properties, and acceptable oral bioavailability (21-50 %) in mice, rats, and dogs. Tumor growth inhibition of greater than 100 % was achieved when immunodeficient mice with rapidly growing paclitaxel-resistant prostate cancer cells were treated orally at doses of 3-30 mg/kg of II or IAT. CONCLUSIONS: These studies highlight the potent and broad anticancer activity of two orally bioavailable compounds, offering significant pharmacologic advantage over existing drugs of this class for multidrug resistant or taxane-refractory cancers.

Estrogen receptor-{beta}-selective ligands alleviate high-fat diet- and ovariectomy-induced obesity in mice.

Obesity is an epidemic problem affecting millions of people in the Western hemisphere and costs the United States economy more than $200 billion annually. Currently, there are no effective treatments to combat obesity. Recent studies have implicated the constitutive activity of estrogen receptor (ER) ß as an important regulator of metabolic diseases. However, the potential of ER-ß-selective ligands to offset obesity is not clear. We evaluated the pharmacological effect of ER-ß-selective ligands (ß-LGNDs) in animal models of high-fat diet- and ovariectomy-induced obesity. Ligand binding, transactivation, and uterotrophic studies with ß-LGNDs demonstrated selectivity for ER-ß over ER-α. Animals fed a high-fat diet showed a significant increase in body weight, and this weight gain was attenuated by ß-LGNDs. High-fat diet-mediated increases in serum cholesterol, leptin, glucose, and fat accumulation in organs were also reduced by ß-LGNDs. In addition, MRI scanning indicated that ß-LGNDs altered body composition by reducing fat mass and increasing lean body mass. Organ weights and gene expression analyses demonstrated that adipose tissue is the center of action for ß-LGNDs, and the reduction in body weight is likely due to increased energy expenditure. In vitro and in vivo mechanistic studies indicated that the anti-obesity effects of ß-LGNDs were due to indirect peroxisome proliferator-activated receptor γ antagonistic actions requiring the ligand binding domain of ER-ß and through abrogation of the ability of PGC-1 to coactivate peroxisome proliferator-activated receptor γ. In conclusion, these studies indicate that ligand-activated ER-ß is a potential therapeutic target to combat obesity and obesity-related metabolic diseases.

Clinical response and pharmacokinetics from a phase 1 study of an active dosing schedule of flavopiridol in relapsed chronic lymphocytic leukemia.

We previously reported interim results of a phase 1 trial in patients with chronic lymphocytic leukemia (CLL) whereby flavopiridol was administered intravenously as a 30-minute bolus followed by 4-hour infusion. We now report full pharmacokinetic (PK) data, correlations of PK with clinical outcomes, and final response and progression-free survival (PFS). Twenty-one (40%) of 52 patients with relapsed CLL achieved a partial response (PR) with a median PFS of 12 months. Responders included 17 (40%) of 43 fludarabine refractory patients, 7 (39%) of 18 patients with del(17p13), and 14 (74%) of 19 patients with del(11q22). Six responders received repeat therapy at relapse, and 5 responded again with a second median PFS of 10 months. Noncompartmental analysis and nonlinear mixed effects modeling was used to estimate PK parameters and evaluate covariates. Two-compartment population parameter estimates were 31.4 L/h, 65.8 L, 8.49 L/h, and 157 L for CL, V1, Q, and V2, respectively. Flavopiridol area under the plasma concentration-time curve (AUC) correlated with clinical response and cytokine release syndrome, and glucuronide metabolite AUC correlated with tumor lysis syndrome. These composite results confirm high activity of this pharmacokinetically derived schedule in relapsed, genetically high-risk CLL. Furthermore, PK describes some, but not all, variability in response and toxicity.

Pharmacokinetic optimization of 4-substituted methoxybenzoyl-aryl-thiazole and 2-aryl-4-benzoyl-imidazole for improving oral bioavailability.

Microtubules are critical components of the cytoskeleton. Perturbing their function arrests the growth of a broad spectrum of cancer cell lines, making microtubules an excellent and established target for chemotherapy. All of the U.S. Food and Drug Administration-approved antitubulin agents bind to paclitaxel or vinblastine binding sites in tubulin. Because of the complexity of their structures, it is difficult to structurally modify the vinca alkaloids and taxanes and develop orally bioavailable agents. Antitubulin agents that target the colchicine-binding site in tubulin may provide a better opportunity to be developed for oral use because of their relatively simple structures and physicochemical properties. A potent antitubulin agent, 4-(3,4,5-trimethoxybenzoyl)-2-phenyl-thiazole (SMART-H), binding to the colchicine-binding site, was discovered in our laboratory. However, the bioavailability of SMART-H was low because of its poor solubility. Structural modification of SMART-H led to the development of 2-aryl-4-benzoyl-imidazole analog (ABI-274), with improved bioavailability and potency but still considerable first-pass metabolism. A chlorine derivative (ABI-286), replacing the methyl site of ABI-274, resulted in 1.5-fold higher metabolic stability in vitro and 1.8-fold lower clearance in rats in vivo, indicating that metabolic stability of ABI-274 can be extended by blocking benzylic hydroxylation. Overall, ABI-274 and ABI-286 provided 2.4- and 5.5-fold increases in exposure (area under the curve) after oral dosing in rats compared with SMART-H. Most importantly, the structural modifications did not compromise potency. ABI-286 exhibited moderate clearance, moderate volume of distribution, and acceptable oral bioavailability. This study provided the first evidence that ABI-286 may be the first member of a new class of orally bioavailable antitubulin agents.

Biotransformation of a novel antimitotic agent, I-387, by mouse, rat, dog, monkey, and human liver microsomes and in vivo pharmacokinetics in mice.

3-(1H-Indol-2-yl)phenyl)(3,4,5-trimethoxyphenyl)methanone (I-387) is a novel indole compound with antitubulin action and potent antitumor activity in various preclinical models. I-387 avoids drug resistance mediated by P-glycoprotein and showed less neurotoxicity than vinca alkaloids during in vivo studies. We examined the pharmacokinetics and metabolism of I-387 in mice as a component of our preclinical development of this compound and continued interest in structure-activity relationships for antitubulin agents. After a 1 mg/kg intravenous dose, noncompartmental pharmacokinetic analysis in plasma showed that clearance (CL), volume of distribution at steady state (Vd(ss)), and terminal half-life (t(1/2)) of I-387 were 27 ml per min/kg, 5.3 l/kg, and 7 h, respectively. In the in vitro metabolic stability study, half-lives of I-387 were between 10 and 54 min by mouse, rat, dog, monkey, and human liver microsomes in the presence of NADPH, demonstrating interspecies variability. I-387 was most stable in rat liver microsomes and degraded quickly in monkey liver microsomes. Liquid chromatography-tandem mass spectrometry was used to identify phase I metabolites. Hydroxylation, reduction of a ketone group, and O-demethylation were the major metabolites formed by the liver microsomes of the five species. The carbonyl group of I-387 was reduced and identified as the most labile site in human liver microsomes. The results of these drug metabolism and pharmacokinetic studies provide the foundation for future structural modification of this pharmacophore to improve stability of drugs with potent anticancer effects in cancer patients.

Cancer cachexia therapy: a key weapon in the fight against cancer.

PURPOSE OF REVIEW: Cachexia affects millions of cancer patients around the world. Though its causes are poorly understood, its devastating impact on the patient and their loved ones underscore the urgency of this unmet medical need. Recent research efforts suggest multiple body systems are dysregulated in cachexia, not only increasing the challenge in effectively treating the disease but also expanding the opportunities for intervention. RECENT FINDINGS: Agents as diverse as anti-inflammatory monoclonal antibodies and novel anabolic small molecules are under clinical evaluation for their ability to prevent and treat wasting. The therapies evaluated to date range in their ability to improve appetite, mitigate weight loss and reverse undesirable changes in body composition and physical function. SUMMARY: An increased understanding of cancer cachexia, both mechanistically and its impact on cancer patients' struggle with their disease, has resulted in diverse therapeutic concepts. Recent clinical efforts demonstrate progress with novel therapies but fall short of effectively treating most cachectic patients and highlight a clear need for further research. Given the inherent heterogeneity of cancer patients and the significant impact of muscle wasting on morbidity and mortality, continued research efforts are critical in developing effective therapies to prevent and treat cancer cachexia.

Mass spectrometric characterization of urinary metabolites of the selective androgen receptor modulator S-22 to identify potential targets for routine doping controls.

Drugs that promote anabolic processes with limited undesirable effects are of considerable therapeutic interest; some notable examples include those for the treatment of cancer cachexia and muscle-wasting diseases. Anabolic properties are not only therapeutically beneficial to critically ill and debilitated patients, but are also desirable to athletes seeking artificial enhancements in endurance, strength and accelerated recovery. The use of anabolic agents in the clinical setting is being reconsidered with the emergence of a new class of drugs referred to as SARMs (selective androgen receptor modulators). SARMs have the potential to complement or even replace anabolic androgenic steroidal use with the benefit of a reduction of the undesirable side effects associated with steroid administration alone. Arylpropionamide-based SARMs such as andarine (S-4) and S-22 have shown promising therapeutic properties and have attracted the interest of elite and amateur athletes despite the absence of clinical approval, and evidence for trafficking and misuse in sport has been obtained by doping control authorities. In this communication, the elucidation of urinary metabolites of the SARM drug candidate S-22 is compared with earlier in vitro metabolism studies. Following oral administration of illicit S-22, urine samples were collected after 62 and 135 h and analyzed for the active drug and its major metabolic products. Liquid chromatography interfaced with high-resolution/high-accuracy (tandem) mass spectrometry was used to identify and/or confirm the predicted target analytes for sports drug testing purposes. S-22 was detected in both specimens accompanied by its glucuronic acid conjugate. This was the B-ring hydroxylated derivative of S-22 plus the corresponding glucuronide (with the phase-II metabolites being the more abundant analytes). In addition, the samples collected 62 h post-administration also contained the phase-I metabolite hydroxylated at the methyl residue (C-20) and the B-ring depleted degradation product ('dephenylated' S-22) together with the corresponding carboxy analog that was previously reported for canine metabolism. The obtained data supports future efforts to effectively screen for and confirm the misuse of the non-approved S-22 drug candidate in doping controls.

Synthesis and antiproliferative activity of novel 2-aryl-4-benzoyl-imidazole derivatives targeting tubulin polymerization.

We previously reported the discovery of 2-aryl-4-benzoyl-imidazoles (ABI-I) as potent antiproliferative agents for melanoma. To further understand the structural requirements for the potency of ABI analogs, gain insight in the structure-activity relationships (SAR), and investigate metabolic stability for these compounds, we report extensive SAR studies on the ABI-I scaffold. Compared with the previous set of ABI-I analogs, the newly synthesized ABI-II analogs have lower potency in general, but some of the new analogs have comparable potency to the most active compounds in the previous set when tested in two melanoma and four prostate cancer cell lines. These SAR studies indicated that the antiproliferative activity was very sensitive to subtle changes in the ligand. Tested compounds 3ab and 8a are equally active against highly paclitaxel resistant cancer cell lines and their parental cell lines, indicating that drugs developed based on ABI-I analogs may have therapeutic advantages over paclitaxel in treating resistant tumors. Metabolic stability studies of compound 3ab revealed that N-methyl imidazole failed to extend stability as literature reported because de-methylation was found as the major metabolic pathway in rat and mouse liver microsomes. However, this sheds light on the possibility for many modifications on imidazole ring for further lead optimization since the modification on imidazole, such as compound 3ab, did not impact the potency.

Drug interaction potential of toremifene and N-desmethyltoremifene with multiple cytochrome P450 isoforms.

Toremifene is an effective agent for the treatment of breast cancer in postmenopausal women and is being evaluated for its ability to prevent bone fractures in men with prostate cancer taking androgen deprivation therapy. Due to the potential for drug-drug interactions, the ability of toremifene and its primary circulating metabolite N-desmethyltoremifene (NDMT) to inhibit nine human cytochrome P450 (CYP) enzymes was determined using human liver microsomes. Induction of CYP1A2 and 3A4 by toremifene was also investigated in human hepatocytes. Toremifene did not significantly inhibit CYP1A2 or 2D6. However, toremifene is a competitive inhibitor of CYP3A4, non-competitive inhibitor of CYP2A6, 2C8, 2C9, 2C19 and 2E1 and mixed-type inhibitor of CYP2B6. CYP inhibition by NDMT was similar in magnitude to toremifene. Toremifene did not induce CYP1A2 but increased CYP3A4 monooxygenase activity and gene expression in drug-exposed human primary hepatocytes. Although clinical doses of toremifene produce steady state exposures to toremifene and NDMT that may be sufficient to cause pharmacokinetic drug-drug interactions with other drugs metabolised by CYP2B6, CYP2C8, CYP3A4, CYP2C9 and CYP2C19, these data indicate that toremifene is unlikely to play a role in clinical drug-drug interactions with substrate drugs of CYP1A2 and CYP2D6.