Evaluation of alternative diluents for clinical use of collagenase clostridium histolyticum (CCH-aaes).

BACKGROUND: Collagenase clostridium histolyticum (CCH-aesthetic formulation [CCH-aaes]; QWO™ [Endo Aesthetics, Malvern PA, USA] is approved as a subcutaneous injection for treatment of cellulite. In the aesthetic practice, dilution of marketed products is commonly employed to tailor treatments to individual patients or off-label locations. Dilution beyond the 0.23 mg/ml achievable with the proprietary diluent supplied with the CCH-aaes lyophilized powder requires diluents readily available in clinic. AIM: To characterize the functionality and stability of CCH-aaes when reconstituted and/or diluted with alternative diluents, including normal saline, bacteriostatic saline, and/or proprietary diluent. PATIENTS/METHODS: Each dilution was assessed for purity using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS PAGE), activity using collagenase (AUX-I) and gelatinase (AUX-II) assays, and aggregation using size-exclusion chromatography. RESULTS: When reconstituted with either saline or proprietary diluent, and diluted with proprietary diluent or saline, purity, activity, and stability of CCH-aaes is maintained for up to 24 h at 5°C or 25°C. In contrast, use of bacteriostatic saline to reconstitute and/or dilute CCH-aaes results in up to a 40% decrease in activity and aggregation of 5.3% of CCH-aaes protein. Importantly, inclusion of 2% lidocaine and 1:200 000 epinephrine does not negatively impact CCH-aaes purity, concentration, or activity for up to 24 h at 5°C or 25°C. CONCLUSIONS: From an efficacy and safety perspective, CCH-aaes must not be/should not be reconstituted and/or diluted with bacteriostatic saline to avoid injection of protein aggregates. Ideally, CCH-aaes should be reconstituted in proprietary diluent: further dilution with normal saline and addition of lidocaine and epinephrine is acceptable.

An Approach to Adapting a Community-Based Cancer Control Intervention to Organizational Context.

There has been increasing attention in implementation science to optimizing the fit of evidence-based interventions to the organizational settings where they are delivered. However, less is known about how to maximize intervention-context fit, particularly in community-based settings. We describe a new strategy to customize evidence-based health promotion interventions to community sites. Specifically, leaders in African American churches completed a memorandum of understanding where they were asked to identify two or more health promotion implementation strategies from a menu of 20 and select a planned implementation time frame for each. In a pilot phase with three churches, the menu-based strategy and protocols were successfully implemented and finalized in preparation for a subsequent randomized trial. The three pilot churches identified between two and nine strategies (e.g., form a health ministry, allocate space or budget for health activities, include health in church communications/sermons). The selected strategies varied widely, reinforcing the need for interventions that can be customized to fit the organizational context. Despite the challenges of integrating health promotion activities into non-health focused organizations, this approach has promise for fostering sustainable health activities in community settings.

Mutation of the BRCA1 SQ-cluster results in aberrant mitosis, reduced homologous recombination, and a compensatory increase in non-homologous end joining.

Mutations in the breast cancer susceptibility 1 (BRCA1) gene are catalysts for breast and ovarian cancers. Most mutations are associated with the BRCA1 N- and C-terminal domains linked to DNA double-strand break (DSB) repair. However, little is known about the role of the intervening serine-glutamine (SQ) - cluster in the DNA damage response beyond its importance in regulating cell cycle checkpoints. We show that serine-to-alanine alterations at critical residues within the SQ-cluster known to be phosphorylated by ATM and ATR result in reduced homologous recombination repair (HRR) and aberrant mitosis. While a S1387A BRCA1 mutant - previously shown to abrogate S-phase arrest in response to radiation - resulted in only a modest decrease in HRR, S1387A together with an additional alteration, S1423A (BRCA12P), reduced HRR to vector control levels and similar to a quadruple mutant also including S1457A and S1524A (BRCA14P). These effects appeared to be independent of PALB2. Furthermore, we found that BRCA14P promoted a prolonged and struggling HRR late in the cell cycle and shifted DSB repair from HRR to non-homologous end joining which, in the face of irreparable chromosomal damage, resulted in mitotic catastrophe. Altogether, SQ-cluster phosphorylation is critical for allowing adequate time for completing normal HRR prior to mitosis and preventing cells from entering G1 prematurely resulting in gross chromosomal aberrations.

The effects of the CXCR2 antagonist, MK-7123, on bone marrow functions in healthy subjects.

The CXCR2 antagonist MK-7123 causes dose-dependent reductions in absolute neutrophil counts (ANC) and decreases neutrophil tissue responses, but its effects on bone marrow functions are not yet known. We conducted a double-blind, randomized study in 18 healthy subjects comparing the effects of either MK-7123 (30mg, po, daily for 28days) or placebo on peripheral blood counts and bone marrow myeloid cell populations. MK-7123 caused a reversible decrease (approximately 50%) in the ANC as demonstrated on days 1 and 28, the first and last days of the treatment period. Bone marrow aspirate smears and biopsy imprints did not differ in the proportion of mature neutrophils in pretreatment, day 28, day 56 or placebo samples. There were no treatment effects on biopsy or aspirate clot cellularity, myeloid to erythroid or myeloid post-mitotic to mitotic ratios; flow-cytometric analyses of aspirate cells; or bone marrow fat to cell balance as assessed by MRI. MK-7123 was generally well tolerated with neutropenia being the most common adverse event; however, there were no clinical symptoms associated with decreased ANCs. These findings indicate that the CXCR2 antagonist MK-7123 causes rapidly reversible decrease in the ANC without measurable myelosuppressive effects. The results support the development of CXCR2 antagonists as potentially useful anti-inflammatory agents, primarily interrupting neutrophil trafficking.

CXCR2 Antagonist MK-7123. A Phase 2 Proof-of-Concept Trial for Chronic Obstructive Pulmonary Disease.

RATIONALE: An antagonist (MK-7123) of the cytokine receptor CXCR2 reduces neutrophil chemotaxis and thus may alleviate airway inflammation in chronic obstructive pulmonary disease (COPD). OBJECTIVES: To assess the efficacy, safety, and tolerability of three dose levels of MK-7123, compared with placebo, in patients with moderate to severe COPD. METHODS: This 6-month, double-blind study randomized patients with moderate to severe COPD (already on standard therapy) to daily MK-7123 at 10, 30, or 50 mg or placebo. The primary endpoint was change from baseline in post-bronchodilator FEV1. MEASUREMENTS AND MAIN RESULTS: A total of 616 patients (71% male; mean age, 63 yr; 45% current smokers; baseline FEV1 [SD], 1.43 L [0.45]; mean FEV1 percent predicted, 43.9%) were randomized. Only MK-7123 50 mg led to significant improvement in FEV1 over placebo (mean difference [SE], 67 ml [32]). Reduced sputum neutrophil count was observed among the 122 patients examined; P = 0.003 (3 mo) and P = 0.092 (6 mo) (MK-7123 50 mg vs. placebo). The stratum of current smokers, but not that of nonsmokers, showed significant improvement versus placebo in FEV1 (168 ml) and time-to-first exacerbation, and showed numerical improvement in St. George's Respiratory Questionnaire for COPD score. MK-7123 caused a dose-dependent decrease in absolute neutrophil count (ANC) and reduced inflammatory biomarkers matrix metallopeptidase-9 and myeloperoxidase in plasma and sputum; ANC lower than 1.5 × 10(9)/L led to discontinuations with higher doses of MK-7123 (18% in the MK-7123 50-mg group vs. 1% in placebo). Plasma C-reactive protein and fibrinogen increased with MK-7123 treatment. Rates of infections at 6 months were similar in all groups. CONCLUSIONS: Treatment with MK-7123 50 mg versus placebo led to significant improvement in FEV1 in patients with COPD, suggesting clinically important antiinflammatory effects with CXCR2 antagonism, although dose-related discontinuations were observed because of ANC decreases with MK-7123. Greater response was observed in smokers versus ex-smokers. Clinical trial registered with www.clinicaltrials.gov (NCT 01006616).

A phase 2, randomized, placebo-controlled, dose-ranging study of the calcium-sensing receptor antagonist MK-5442 in the treatment of postmenopausal women with osteoporosis.

CONTEXT: MK-5442 is an orally bioavailable calcium-sensing receptor antagonist that is hypothesized to stimulate bone formation by stimulating endogenous secretion of a pulse of PTH. Earlier clinical and preclinical studies demonstrated increased bone mineral density (BMD) after treatment. OBJECTIVE: Our objective was to identify a dose of MK-5442 that produces osteoanabolic effects without excessive hypercalcemia. DESIGN AND SETTING: This was a randomized, double-blind, placebo-controlled, parallel-group trial of private or institutional practice. PARTICIPANTS AND INTERVENTION: In total, 383 postmenopausal women with osteoporosis were administered daily oral MK-5442 (2.5, 5, 7.5, 10, or 15 mg) or placebo. MAIN OUTCOME MEASURES: Serum PTH and calcium, bone turnover markers, areal BMD, and safety were evaluated. RESULTS: A dose-dependent transient increase in PTH occurred after an MK-5442 dose and lasted more than 3.5 hours. Compared with placebo, significant increases in bone formation markers (serum procollagen 1 N-terminal peptide and bone-specific alkaline phosphatase) were observed by 6 months, whereas bone resorption markers (serum C-telopeptide of type 1 collagen, urine N-telopeptides of type 1 collagen) initially decreased but were also significantly increased by 6 months. Despite the biochemical marker changes suggestive of an anabolic response, there were no statistically significant differences between any dose of MK-5442 and placebo in percent change from baseline at month 6 in any of the BMD endpoints. The frequency of hypercalcemia (trough serum calcium ≥ 10.8 mg/dL) was greater with higher MK-5442 doses. CONCLUSION: In postmenopausal women with low bone mass, treatment with MK-5442 resulted in transient pulses of PTH. Bone formation markers increased quickly and bone resorption markers decreased temporarily, suggestive of an anabolic window. However, there were no increases in BMD versus placebo.

Effects of odanacatib on the radius and tibia of postmenopausal women: improvements in bone geometry, microarchitecture, and estimated bone strength.

The cathepsin K inhibitor odanacatib (ODN), currently in phase 3 development for postmenopausal osteoporosis, has a novel mechanism of action that reduces bone resorption while maintaining bone formation. In phase 2 studies, odanacatib increased areal bone mineral density (aBMD) at the lumbar spine and total hip progressively over 5 years. To determine the effects of ODN on cortical and trabecular bone and estimate changes in bone strength, we conducted a randomized, double-blind, placebo-controlled trial, using both quantitative computed tomography (QCT) and high-resolution peripheral (HR-p)QCT. In previously published results, odanacatib was superior to placebo with respect to increases in trabecular volumetric BMD (vBMD) and estimated compressive strength at the spine, and integral and trabecular vBMD and estimated strength at the hip. Here, we report the results of HR-pQCT assessment. A total of 214 postmenopausal women (mean age 64.0 ± 6.8 years and baseline lumbar spine T-score -1.81 ± 0.83) were randomized to oral ODN 50 mg or placebo, weekly for 2 years. With ODN, significant increases from baseline in total vBMD occurred at the distal radius and tibia. Treatment differences from placebo were also significant (3.84% and 2.63% for radius and tibia, respectively). At both sites, significant differences from placebo were also found in trabecular vBMD, cortical vBMD, cortical thickness, cortical area, and strength (failure load) estimated using finite element analysis of HR-pQCT scans (treatment differences at radius and tibia = 2.64% and 2.66%). At the distal radius, odanacatib significantly improved trabecular thickness and bone volume/total volume (BV/TV) versus placebo. At a more proximal radial site, odanacatib attenuated the increase in cortical porosity found with placebo (treatment difference = -7.7%, p = 0.066). At the distal tibia, odanacatib significantly improved trabecular number, separation, and BV/TV versus placebo. Safety and tolerability were similar between treatment groups. In conclusion, odanacatib increased cortical and trabecular density, cortical thickness, aspects of trabecular microarchitecture, and estimated strength at the distal radius and distal tibia compared with placebo.

Diary of hot flashes reported upon occurrence: results of a randomized double-blind study of raloxifene, placebo, and paroxetine.

OBJECTIVE: This trial examined diaries of hot flash events reported upon occurrence to assess the test/retest reliability of the diaries and their ability to measure treatment effects on hot flash frequency and severity. METHODS: Forty-two postmenopausal women (aged ≥40 y; 5-50 hot flashes/wk) were randomized (3:3:1) to placebo, raloxifene 60 mg, or paroxetine 20 mg daily for 12 weeks. Diaries of hot flash frequency and severity were evaluated at 1-week intervals (twice before study treatment and thrice during study treatment). RESULTS: Forty-one women were evaluated. Baseline characteristics were similar between groups (eg, mean, 29.8 hot flashes/wk). Concordance correlation coefficients between screening (week -2) and baseline (week -1) measures of hot flash frequency and severity were 0.73 and 0.71, respectively. After 12 weeks, the mean (95% CI) percent changes from baseline in weekly hot flash frequency were as follows: placebo, -37.4% (-60.9 to -14.0); raloxifene, -14.2% (-37.7 to 9.3); paroxetine, -49.8% (-88.6 to -11.0); the mean (95% CI) percent changes in hot flash severity were as follows: placebo, -39.9% (-69.1 to -10.8); raloxifene, -9.6% (-38.8 to 19.6); paroxetine, -36.6% (-84.7 to 11.5). There were no significant differences in hot flash diary results between treatment groups. CONCLUSIONS: Measures of hot flash frequency and severity show acceptable test/retest reliability between screening and baseline. Reductions in vasomotor symptoms by raloxifene are numerically less than those seen with placebo, but no statistically significant treatment differences have been documented in this small study. The large effect of placebo and the significant reduction in vasomotor symptoms by paroxetine are consistent with other studies. The diary seems to be suitable for use in hot flash clinical trials.

Vitamin D status and bone mineral density changes during alendronate treatment in postmenopausal osteoporosis.

Vitamin D supplementation is recommended for women with osteoporosis. In the FOCUS-D trial comparing the combination tablet alendronate plus vitamin D3 5,600 IU (ALN/D) with standard care (SC) prescribed by patients' personal physicians, ALN/D was more effective in improving serum 25(OH)D and bone turnover markers by 6 months and increasing spine and hip bone mineral density (BMD) after 1 year than SC. This post hoc analysis examined the relationship between BMD gain and 25(OH)D in women in SC receiving alendronate (SC/ALN, n = 134, 52% of the SC group) and in the ALN/D group (n = 257). At baseline, participants were of mean age 73 years and 72% were Caucasian, with a mean 25(OH)D of 14.9 ng/mL. In the SC/ALN group, most received vitamin D, although intake of vitamin D varied extensively (51% received <400 µg/day). In this group, end-of-study 25(OH)D correlated positively with mean percent increases from baseline in lumbar spine and femoral neck BMD [Pearson correlation coefficients (95% CI) = 0.23 (0.02-0.41) and 0.24 (0.03-0.41), respectively]. Baseline 25(OH)D correlated with increases in only lumbar spine BMD [Pearson correlation coefficient (95% CI) = 0.22 (0.01-0.40)]. No correlations between mean BMD change and 25(OH)D were seen with ALN/D. In conclusion, in postmenopausal women with osteoporosis and low 25(OH)D receiving alendronate and a wide range of vitamin D doses, the increase in lumbar spine and femoral neck BMD was positively correlated with serum 25(OH)D achieved by the end of the study and, to some extent, with 25(OH)D concentrations at baseline. The degree of success of alendronate therapy for osteoporosis may depend on the vitamin D status of patients.

The Influence of Hypoxia and pH on Bioluminescence Imaging of Luciferase-Transfected Tumor Cells and Xenografts.

Bioluminescence imaging (BLI) is a relatively new noninvasive technology used for quantitative assessment of tumor growth and therapeutic effect in living animal models. BLI involves the generation of light by luciferase-expressing cells following administration of the substrate luciferin in the presence of oxygen and ATP. In the present study, the effects of hypoxia, hypoperfusion, and pH on BLI signal (BLS) intensity were evaluated in vitro using cultured cells and in vivo using a xenograft model in nude mice. The intensity of the BLS was significantly reduced in the presence of acute and chronic hypoxia. Changes in cell density, viability, and pH also affected BLS. Although BLI is a convenient non-invasive tool for tumor assessment, these factors should be considered when interpreting BLS intensity, especially in solid tumors that could be hypoxic due to rapid growth, inadequate blood supply, and/or treatment.

ATM kinase inhibition preferentially sensitizes p53-mutant glioma to ionizing radiation.

PURPOSE: Glioblastoma multiforme (GBM) is the most lethal form of brain cancer with a median survival of only 12 to 15 months. Current standard treatment consists of surgery followed by chemoradiation. The poor survival of patients with GBM is due to aggressive tumor invasiveness, an inability to remove all tumor tissue, and an innate tumor chemo- and radioresistance. Ataxia-telangiectasia mutated (ATM) is an excellent target for radiosensitizing GBM because of its critical role in regulating the DNA damage response and p53, among other cellular processes. As a first step toward this goal, we recently showed that the novel ATM kinase inhibitor KU-60019 reduced migration, invasion, and growth, and potently radiosensitized human glioma cells in vitro. EXPERIMENTAL DESIGN: Using orthotopic xenograft models of GBM, we now show that KU-60019 is also an effective radiosensitizer in vivo. Human glioma cells expressing reporter genes for monitoring tumor growth and dispersal were grown intracranially, and KU-60019 was administered intratumorally by convection-enhanced delivery or osmotic pump. RESULTS: Our results show that the combined effect of KU-60019 and radiation significantly increased survival of mice 2- to 3-fold over controls. Importantly, we show that glioma with mutant p53 is much more sensitive to KU-60019 radiosensitization than genetically matched wild-type glioma. CONCLUSIONS: Taken together, our results suggest that an ATM kinase inhibitor may be an effective radiosensitizer and adjuvant therapy for patients with mutant p53 brain cancers.

BMD changes and predictors of increased bone loss in postmenopausal women after a 5-year course of alendronate.

Management of women discontinuing bisphosphonates after 3 to 5 years of treatment is controversial. Little is known about how much bone mineral density (BMD) is lost after discontinuation or whether there are risk factors for greater rates of bone loss post-discontinuation. We report patterns of change in BMD and prediction models for the changes in BMD in postmenopausal women during a 5-year treatment-free period after alendronate (ALN) therapy. We studied 406 women enrolled in the Fracture Intervention Trial (FIT) who had taken ALN for a mean of 5 years and were then enrolled in the placebo arm of the FIT Long-Term Extension (FLEX) trial for an additional 5 years, describing 5-year percent changes in total hip, femoral neck, and lumbar spine BMD over the treatment-free period. Prediction models of 5-year percent changes in BMD considered all linear combinations of candidate risk factors for bone loss such as BMD at the start of the treatment-free period, the change in BMD on ALN, age, and fracture history. Serum for three markers of bone turnover was available in 76 women, and these bone turnover markers were included as candidate predictors for these 76 women. Mean 5-year BMD changes were -3.6% at the total hip, -1.7% at the femoral neck, and 1.3% at the lumbar spine. Five-year BMD losses of >5% were experienced by 29% of subjects at the total hip, 11% of subjects at the femoral neck, and 1% of subjects at the lumbar spine. Several risk factors such as age and BMI were associated with greater bone loss, but no models based on these risk factors predicted bone loss rates. Although about one-third of women who discontinued ALN after 5 years experienced >5% bone loss at the total hip, predicting which women will lose at a higher rate was not possible.

Parametric estimation of 3D tubular structures for diffuse optical tomography.

We explore the use of diffuse optical tomography (DOT) for the recovery of 3D tubular shapes representing vascular structures in breast tissue. Using a parametric level set method (PaLS) our method incorporates the connectedness of vascular structures in breast tissue to reconstruct shape and absorption values from severely limited data sets. The approach is based on a decomposition of the unknown structure into a series of two dimensional slices. Using a simplified physical model that ignores 3D effects of the complete structure, we develop a novel inter-slice regularization strategy to obtain global regularity. We report on simulated and experimental reconstructions using realistic optical contrasts where our method provides a more accurate estimate compared to an unregularized approach and a pixel based reconstruction.

In vitro and in vivo responses to high and low doses of nitrogen-containing bisphosphonates suggest engagement of different mechanisms for inhibition of osteoclastic bone resorption.

The effects of nitrogen-containing bisphosphonates (N-BPs) on osteoclasts (Ocs) may differ with dose and regimen. N-BPs reduce Oc bone resorption by inhibiting the enzyme farnesyl diphosphate synthase (FPPS), an effect counteracted by geranylgeraniol (GGOH), which restores geranylgeranylation downstream of FPPS. We assessed GGOH effects on inhibition of bone resorption by the N-BPs alendronate (ALN), ibandronate (IBN), and zoledronate (ZOL) in an assay of rabbit Oc resorption of bovine cortical bone. GGOH blocked inhibition of resorption at low, but not high, N-BP concentrations, with a 14- to 20-fold increase in IC50 values for each N-BP. In vivo, growing male rats were administered doses calculated to mimic bioavailable exposures in daily (ALN, IBN), weekly (ALN), monthly (IBN), and yearly (ZOL) clinical regimens. Tibiae were harvested at 48 h, and metaphyses were analyzed. With lower ALN and IBN doses, Oc numbers rose by 26-48 %, morphology was normal, and there was no increase in apoptotic Ocs. In contrast, with higher IBN and ZOL doses, bone-associated Ocs were generally rounded in appearance and numbers of nuclei/Oc versus vehicle increased 42 and 31 %, respectively (P < 0.05). With ZOL, there was no rise in Oc number, but there was a 6.5-fold increase in apoptotic Ocs versus vehicle and a ≥13.5-fold increase versus lower-dose ALN or IBN (P < 0.05). With higher-dose IBN there was no rise in Oc number but 7- and 14-fold increases in Oc apoptosis versus low-dose ALN and IBN (P < 0.02). These results suggest that different mechanisms may come into play across the dosing spectrum of N-BPs.

Bone density, turnover, and estimated strength in postmenopausal women treated with odanacatib: a randomized trial.

CONTEXT: Odanacatib, a cathepsin K inhibitor, increases spine and hip areal bone mineral density (BMD) in postmenopausal women with low BMD and cortical thickness in ovariectomized monkeys. OBJECTIVE: The objective of the study was to examine the impact of odanacatib on the trabecular and cortical bone compartments and estimated strength at the hip and spine. DESIGN: This was a randomized, double-blind, 2-year trial. SETTING: The study was conducted at a private or institutional practice. PARTICIPANTS: PARTICIPANTS included 214 postmenopausal women with low areal BMD. INTERVENTION: The intervention included odanacatib 50 mg or placebo weekly. MAIN OUTCOME MEASURES: Changes in areal BMD by dual-energy x-ray absorptiometry (primary end point, 1 year areal BMD change at lumbar spine), bone turnover markers, volumetric BMD by quantitative computed tomography (QCT), and bone strength estimated by finite element analysis were measured. RESULTS: Year 1 lumbar spine areal BMD percent change from baseline was 3.5% greater with odanacatib than placebo (P < .001). Bone-resorption marker C-telopeptide of type 1 collagen was significantly lower with odanacatib vs placebo at 6 months and 2 years (P < .001). Bone-formation marker procollagen I N-terminal peptide initially decreased with odanacatib but by 2 years did not differ from placebo. After 6 months, odanacatib-treated women had greater increases in trabecular volumetric BMD and estimated compressive strength at the spine and integral and trabecular volumetric BMD and estimated strength at the hip (P < .001). At the cortical envelope of the femoral neck, bone mineral content, thickness, volume, and cross-sectional area also increased from baseline with odanacatib vs placebo (P < .001 at 24 months). Adverse experiences were similar between groups. CONCLUSIONS: Over 2 years, odanacatib decreased bone resorption, maintained bone formation, increased areal and volumetric BMD, and increased estimated bone strength at both the hip and spine.

The osteoclast, bone remodelling and treatment of metabolic bone disease.

BACKGROUND: Bone remodelling maintains skeletal integrity by osteoclasts removing foci of damaged bone and osteoblasts replacing them with new bone. Diseases associated with increased bone resorption have increased remodelling often with inadequate bone formation and increased risk of fracture. New therapies are needed for these diseases to reduce resorption and increase formation. DESIGN: The molecular mechanisms regulating osteoclast and osteoblast functions have become better understood in the past 20 years and have led to questioning of the long-held notion that osteoblastic cells have the dominant regulatory role over osteoclastic cells in bone remodelling. Here, we review current knowledge of how osteoclast formation and functions are regulated and describe how enhanced understanding of these has led to development of new drugs for the management of common bone diseases characterized by increased bone resorption. RESULTS: Osteoclast formation and functions are regulated by cytokines, especially receptor activator of NF-κB ligand (RANKL) and macrophage-colony-stimulating factor (M-CSF). The differentiation, activity and lifecycle of osteoclasts are regulated in part by other cells that reside within the bone. These include osteoblasts, osteocytes and immune cells, which express these cytokines in response to most factors that promote bone resorption. RANKL and M-CSF activate numerous signalling pathways, which are potential targets for therapeutic intervention. Importantly, osteoclastic cells also function as positive and negative regulators of osteoblastic bone formation. CONCLUSIONS: There are multiple targets within osteoclasts for pharmacologic intervention to prevent bone loss in osteoporosis and other resorptive bone diseases. However, novel therapies could also affect osteoblastic cell functions.

Odanacatib in the treatment of postmenopausal women with low bone mineral density: five years of continued therapy in a phase 2 study.

Odanacatib (ODN) is a selective inhibitor of the collagenase cathepsin K that is highly expressed by osteoclasts. In this 2-year, phase 2, dose-ranging trial, postmenopausal women with bone mineral density (BMD) T-scores -2.0 to -3.5 at spine or hip were randomized to weekly placebo or ODN 3, 10, 25, or 50 mg plus vitamin D(3) and calcium. Prespecified trial-extensions continued through 5 years. In year 3, all women were re-randomized to ODN 50 mg or placebo. For years 4 and 5, women who received placebo or ODN 3 mg in years 1 and 2 and placebo in year 3 received ODN 50 mg; others continued year 3 treatments. Endpoints included lumbar spine (primary), hip, 1/3 radius, and total body BMD; markers of bone metabolism; and safety. Women in the year 4 to 5 extension receiving placebo (n = 41) or ODN 50 mg (n = 100) had similar baseline characteristics. For women who received ODN (10-50 mg) for 5 years, spine and hip BMD increased over time. With ODN 50 mg continually for 5 years (n = 13), mean lumbar spine BMD percent change from baseline (95% confidence interval [CI]) was 11.9% (7.2% to 16.5%) versus -0.4% (-3.1% to 2.3%) for women who were switched from ODN 50 mg to placebo after 2 years (n = 14). In pooled results of women receiving continuous ODN (10-50 mg, n = 26-29), year 5 geometric mean percent changes from baseline in bone resorption markers cross-linked N-telopeptide of type I collagen (NTX)/creatinine and cross-linked C-telopeptide (CTX) were approximately -55%, but near baseline for bone formation markers bone-specific alkaline phosphatase (BSAP) and amino-terminal propeptide of type I procollagen (P1NP). In women switched from ODN 10 to 50 mg to placebo after 2 years (n = 25), bone turnover markers were near baseline. In summary, women receiving combinations of ODN (10-50 mg) for 5 years had gains in spine and hip BMD and showed larger reductions in bone resorption than bone formation markers. Discontinuation of ODN resulted in reversal of treatment effects. Treatment with ODN for up to 5 years was generally well-tolerated.

Dynamic inhibition of ATM kinase provides a strategy for glioblastoma multiforme radiosensitization and growth control.

Glioblastoma multiforme (GBM) is notoriously resistant to treatment. Therefore, new treatment strategies are urgently needed. ATM elicits the DNA damage response (DDR), which confers cellular radioresistance; thus, targeting the DDR with an ATM inhibitior (ATMi) is very attractive. Herein, we show that dynamic ATM kinase inhibition in the nanomolar range results in potent radiosensitization of human glioma cells, inhibits growth and does not conflict with temozolomide (TMZ) treatment. The second generation ATMi analog KU-60019 provided quick, reversible and complete inhibition of the DDR at sub-micromolar concentrations in human glioblastoma cells. KU-60019 inhibited the phosphorylation of the major DNA damage effectors p53, H2AX and KAP1 as well as AKT. Colony-forming radiosurvival showed that continuous exposure to nanomolar concentrations of KU-60019 effectively radiosensitized glioblastoma cell lines. When cells were co-treated with KU-60019 and TMZ, a slight increase in radiation-induced cell killing was noted, although TMZ alone was unable to radiosensitize these cells. In addition, without radiation, KU-60019 with or without TMZ reduced glioma cell growth but had no significant effect on the survival of human embryonic stem cell (hESC)-derived astrocytes. Altogether, transient inhibition of the ATM kinase provides a promising strategy for radiosensitizing GBM in combination with standard treatment. In addition, without radiation, KU-60019 limits growth of glioma cells in co-culture with human astrocytes that seem unaffected by the same treatment. Thus, inter-fraction growth inhibition could perhaps be achieved in vivo with minor adverse effects to the brain.

Inhibition of cathepsin K for treatment of osteoporosis.

Cathepsin K is the protease that is primarily responsible for the degradation of bone matrix by osteoclasts. Inhibitors of cathepsin K are in development for treatment of osteoporosis. Currently available antiresorptive drugs interfere with osteoclast function. They inhibit both bone resorption and formation, due to the coupling between these processes. Cathepsin K inhibitors, conversely, target the resorption process itself and may not interfere with osteoclast stimulation of bone formation. In fact, when cathepsin K is absent or inhibited in mice, rabbits, or monkeys, bone formation is maintained or increased. In humans, inhibition of cathepsin K is associated with sustained reductions in bone resorption markers but with smaller and transient reductions in bone formation markers. The usefulness of cathepsin K inhibitors in osteoporosis is now being examined in phase 2 and phase 3 clinical trials of postmenopausal osteoporotic women.