Chris Reading

16α-Bromoepiandrosterone Restores T Helper Cell Type 1 Activity and Accelerates Chemotherapy-Induced Bacterial Clearance in a Model of Progressive Pulmonary Tuberculosis

BALB/c mice with pulmonary tuberculosis develop a T helper cell type 1 response that peaks at 3 weeks, temporarily controlling bacterial growth. Then bacterial proliferation recommences, accompanied by increasing interleukin (IL)-4 levels and decreasing interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha, and inducible nitric oxide synthase (iNOS) levels. These changes mimic those in the human disease. In a previous study, administration of dehydroepiandrosterone (DHEA) beginning on day 60 after infection reversed these changes and protected the mice. However, DHEA is suboptimal for human use, partly because it is readily metabolized into sex steroids. 16alpha-Bromoepiandrosterone (EpiBr; 16alpha -bromo-5alpha -androstan-3beta-ol-17-one) is a synthetic adrenal steroid derivative that does not enter sex steroid pathways. In the present study, when tuberculous BALB/c mice were treated with EpiBr 3 times/week beginning on day 60, inhibition of bacterial proliferation and increased expression of TNF-alpha, IFN-gamma, and iNOS were observed, although decreased expression of IL-4 was also observed. Moreover, when given as an adjunct to conventional chemotherapy, EpiBr enhanced bacterial clearance. Trials for the use of EpiBr in the treatment of human tuberculosis are now justified.

Amelioration of Glucose Intolerance by the Synthetic Androstene HE3286: Link to Inflammatory Pathways

Insulin resistance, the major metabolic abnormality underlying type 2 diabetes, is associated with chronic inflammation and heavy macrophage infiltration in white adipose tissue (WAT). The therapeutic properties of the synthetic adrenal steroid Δ5-androstene-17α-ethynyl-3β,7β,17β-triol (HE3286) were characterized in metabolic disease models. Treatment of diabetic db/db mice with HE3286 suppressed progression to hyperglycemia and markedly improved glucose clearance. Similar effects were also observed in insulin-resistant, diet-induced obese C57BL/6J mice and genetically obese ob/ob mice. This effect appeared to be a consequence of reduced insulin resistance because HE3286 lowered blood insulin levels in db/db and ob/ob mice. Treatment with HE3286 was accompanied by suppressed expression of the prototype macrophage-attracting chemokine monocyte chemoattractant protein-1 in WAT, along with its cognate receptor C-C motif chemokine receptor-2. Exposure of mouse macrophages to HE3286 in vitro caused partial suppression of endotoxin (lipopolysaccharide)-induced nuclear factor κ-B (NF-κB)-sensitive reporter gene expression, NF-κB nuclear translocation, and NF-κB/p65 serine phosphorylation. Proinflammatory kinases, including IκB kinase, c-Jun NH2-terminal kinase, and p38, were also inhibited by HE3286. In ligand competition experiments HE3286 did not bind to classical sex steroid or corticosteroid receptors, including androgen receptor (AR), progesterone receptor, estrogen receptor (ER) α or ERβ, and glucocorticoid receptor (GR). Likewise, in cells expressing nuclear receptor-sensitive reporter genes HE3286 did not substantially stimulate transactivation of AR, ER, GR, or peroxisome proliferator-activated receptor (PPAR) α, PPARδ, and PPARγ. These findings indicate that HE3286 improves glucose homeostasis in diabetic and insulin-resistant mice and suggest that the observed therapeutic effects result from attenuation of proinflammatory pathways, independent of classic sex steroid receptors, corticosteroid receptors, or PPARs.

Parasiticidal effect of 16α-bromoepiandrosterone (EpiBr) in amoebiasis and cysticercosis

The effect of the dehydroepiandrosterone analog 16alpha-bromoepiandrosterone (EpiBr) was tested on the tapeworm Taenia crassiceps and the protist Entamoeba histolytica, both in vivo and in vitro. Administration of EpiBr prior to infection with cysticerci in mice reduced the parasite load by 50% compared with controls. EpiBr treatment induced 20% reduction on the development of amoebic liver abscesses in hamsters. In vitro treatment of T. crassiceps and E. histolytica cultures with EpiBr, reduced reproduction, motility and viability in a dose- and time-dependent fashion. These results leave open the possibility of assessing the potential of this hormonal analog as a possible anti-parasite drug, including cysticercosis and amoebiasis.

17α-Alkynyl 3α, 17β-androstanediol non-clinical and clinical pharmacology, pharmacokinetics and metabolism

Summary17α-ethynyl-5α-androstane-3α, 17β-diol (HE3235, Apoptone) is an orally bioavailable synthetic analogue of 3β-androstanediol, that is active in rodent models of prostate and breast cancer, and is in Phase IIa clinical trials for the treatment of early- and late-stage prostate cancer. In preparation for clinical studies, nuclear hormone receptor and P450 interactions for HE3235 and major metabolites were characterized in vitro, and pharmacokinetics and metabolite profiles were studied in rodents, dogs, and monkeys. Four-week safety studies conducted in rats and dogs indicated a substantial margin of safety for clinical use, and no evidence of electrocardiographic or neurological effects, although anorexia, thrombocytopenia, and hypokalemia were identified as potentially dose-limiting toxicities at superpharmacological exposures. Pharmacokinetics and drug metabolism have been studied in prostate cancer patients.

5-Androstene-3β,17β-diol Promotes Recovery of Immature Hematopoietic Cells Following Myelosuppressive Radiation and Synergizes With Thrombopoietin

PURPOSE 5-Androstene-3β,17β-diol (5-AED) stimulates recovery of hematopoiesis after exposure to radiation. To elucidate its cellular targets, the effects of 5-AED alone and in combination with (pegylated) granulocyte colony-stimulating factor and thrombopoietin (TPO) on immature hematopoietic progenitor cells were evaluated following total body irradiation. METHODS AND MATERIALS BALB/c mice were exposed to radiation delivered as a single or as a fractionated dose, and recovery of bone marrow progenitors and peripheral blood parameters was assessed. RESULTS BALB/c mice treated with 5-AED displayed accelerated multilineage blood cell recovery and elevated bone marrow (BM) cellularity and numbers of progenitor cells. The spleen colony-forming unit (CFU-S) assay, representing the life-saving short-term repopulating cells in BM of irradiated donor mice revealed that combined treatment with 5-AED plus TPO resulted in a 20.1-fold increase in CFU-S relative to that of placebo controls, and a 3.7 and 3.1-fold increase in comparison to 5-AED and TPO, whereas no effect was seen of Peg-G-CSF with or without 5-AED. Contrary to TPO, 5-AED also stimulated reconstitution of the more immature marrow repopulating (MRA) cells. CONCLUSIONS 5-AED potently counteracts the hematopoietic effects of radiation-induced myelosuppression and promotes multilineage reconstitution by stimulating immature bone marrow cells in a pattern distinct from, but synergistic with TPO.

An Anti-Inflammatory Sterol Decreases Obesity-Related Inflammation-Induced Insulin Resistance and Metabolic Dysregulation

Obesity-related inflammation-induced insulin resistance and metabolic dysregulation were investigated in retrospective analysis of placebo hematologic and metabolic laboratory data from trials associated with increasing chronic low-grade inflammation and body mass index. Studies included healthy subjects and those with progressive stages of metabolic dysregulation, including type 2 diabetes mellitus with uncontrolled hemoglobin A1c. Intrasubject variances in erythroid and metabolic values increased with metabolic dysregulation. Random effects were demonstrated in treatment-naïve diabetes for erythroid, glucose, and HbA1c fluctuations. The anti-inflammatory insulin sensitizer, HE3286, was tested for its ability to decrease obesity-related inflammation-induced insulin resistance and metabolic dysregulation in diabetes. HE3286 significantly decreased erythroid and metabolic variances and improved 1,5-anhydroglucitol (a surrogate of postprandial glucose) compared to the placebo group. HE3286 HbA1c decrease correlated with weight loss and inversely with baseline monocyte chemoattractant protein-1 (MCP-1) in metformin-treated diabetics. Normalization of HbA1c to the 84-day average hemoglobin revealed that HE3286 HbA1c decrease correlated with high baseline MCP-1 and MCP-1 decrease in treatment-naïve diabetics. HE3286 decreased insulin resistance, increased the frequency of decreased day 84 HbA1c in metformin-treated subjects, and decreased day 112 HbA1c in treatment-naïve diabetics. HE3286 may be useful to restore metabolic homeostasis in type 2 diabetes.

A New Parasiticidal Compound in T. solium Cysticercosis

The effect of 16α-bromoepiandrosterone (EpiBr), a dehydroepiandrosterone (DHEA) analogue, was tested on the cysticerci of Taenia solium, both in vitro and in vivo. In vitro treatment of T. solium cultures with EpiBr reduced scolex evagination, growth, motility, and viability in dose- and time-dependent fashions. Administration of EpiBr prior to infection with T. solium cysticerci in hamsters reduced the number and size of developed taenias in the intestine, compared with controls. These effects were associated to an increase in splenocyte proliferation in infected hamsters. These results leave open the possibility of assessing the potential of this hormonal analogue as a possible antiparasite drug, particularly in cysticercosis and taeniosis.

Abstract A221: Results of preclinical and clinical phase I/II open‐label dose‐ranging trial with HE3235, a synthetic adrenal hormone, in castrate‐resistant prostate cancer

Background: HE3235 (17α‐ethynyl‐5α‐androstane‐3α, 17β‐diol) is an androstenediol analog, which shows activity in preclinical CRPC and breast cancer models. HE3235 decreased AR expression in LNCaP cells in vitro, in the CRPC LuCaP 35V xenograft, and suppressed ER‐a expression in MNU‐induced breast tumors in rats. HE3235 also decreased intra‐tumoral androgen synthesis (both T and DHT) in the LuCaP 35V tumors. In toxicology studies, it decreased steroidogenesis (DHEA and T in male dogs and sex steroids in female rats). HE3235 did not inhibit CYP17 in H295R adrenal tumor cells, but inhibited the conversion of d‐cholesterol to d‐pregnenolone. We are therefore conducting a Phase I/II clinical study in CRPC patients to determine safety, tolerance, pharmacokinetics, maximum tolerated dose and activity of this compound. Methods: Men with CRPC and an ECOG PS of Results: 22 subjects have been treated to date at doses of 10 mg/day (n=7), 20 mg/day (n=9) and 30 mg/day (n=6). Dose escalation continues to determine the MTD. Pharmacokinetics was dose proportional with a drug half‐life of 11–14 hours. HE3235 was well tolerated. Nine of 22 subjects experienced a drop in PSA during treatment with 6 of 22 equal to or greater than 20%. No patient had a 50% decline in PSA. Eight of 17 (47%) subjects who were evaluable for response had stable disease. Median time to progression was 56 days (IQR 55, 224) for 10 mg/day, 112 days (IQR 56, 168) for 20 mg/days, 112 days (IQR 56, >122) for 30 mg/day and 112 days (IQR 56, 168) for all 22 subjects. Conclusion: HE3235 is a novel, small orally delivered compound with preclinical activity for CRPC. It is well tolerated through a dose of 30 mg, and has a T1/2 linear to dose in cohorts tested to date. The trial continues to accrue, and a cohort of patients with chemotherapy‐naive CRPC will be enrolled into the ongoing Phase I/II Study. Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A221.