Assessment of cognitive safety in clinical drug development.

Cognitive impairment is increasingly recognised as an important potential adverse effect of medication. However, many drug development programmes do not incorporate sensitive cognitive measurements. Here, we review the rationale for cognitive safety assessment, and explain several basic methodological principles for measuring cognition during clinical drug development, including study design and statistical analysis, from Phase I through to postmarketing. The crucial issue of how cognition should be assessed is emphasized, especially the sensitivity of measurement. We also consider how best to interpret the magnitude of any identified effects, including comparison with benchmarks. We conclude by discussing strategies for the effective communication of cognitive risks.

Effect of tarenflurbil on cognitive decline and activities of daily living in patients with mild Alzheimer disease: a randomized controlled trial.

CONTEXT: Amyloid-beta peptide (Abeta(42)) has been implicated in the pathogenesis of Alzheimer disease (AD). Tarenflurbil, a selective Abeta(42)-lowering agent, demonstrated encouraging results on cognitive and functional outcomes among mildly affected patients in an earlier phase 2 trial. OBJECTIVE: To determine the efficacy, safety, and tolerability of tarenflurbil. DESIGN, SETTING, AND PATIENTS: A multicenter, randomized, double-blind, placebo-controlled trial enrolling patients with mild AD was conducted at 133 trial sites in the United States between February 21, 2005, and April 30, 2008. Concomitant treatment with cholinesterase inhibitors or memantine was permitted. INTERVENTION: Tarenflurbil, 800 mg, or placebo, administered twice a day. MAIN OUTCOME MEASURES: Co-primary efficacy end points were the change from baseline to month 18 in total score on the subscale of the Alzheimer Disease Assessment Scale-Cognitive Subscale (ADAS-Cog, 80-point version) and Alzheimer Disease Cooperative Studies-activities of daily living (ADCS-ADL) scale. Additional prespecified slope analyses explored the possibility of disease modification. RESULTS: Of the 1684 participants randomized, 1649 were included in the analysis, and 1046 completed the trial. Tarenflurbil had no beneficial effect on the co-primary outcomes (difference in change from baseline to month 18 vs placebo, based on least squares means: 0.1 for ADAS-Cog; 95% CI, -0.9 to 1.1; P = .86 and -0.5 for ADCS-ADL; 95% CI, -1.9 to 0.9; P = .48) using an intent-to-treat analysis. No significant differences occurred in the secondary outcomes. The ADAS-Cog score decreased by 7.1 points over 18 months. The tarenflurbil group had a small increase in frequency of dizziness, anemia, and infections. CONCLUSION: Tarenflurbil did not slow cognitive decline or the loss of activities of daily living in patients with mild AD. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00105547.

Efficacy and safety of tarenflurbil in mild to moderate Alzheimer's disease: a randomised phase II trial.

BACKGROUND: The amyloid-beta peptide Abeta(42) has been implicated in the pathogenesis of Alzheimer's disease (AD). We aimed to test the effects of tarenflurbil, a selective Abeta(42)-lowering agent (SALA), on cognition and function in patients with mild to moderate AD. METHODS: 210 patients living in the community who had a mini-mental state examination (MMSE) score of 15-26 were randomly assigned to receive tarenflurbil twice per day (400 mg [n=69] or 800 mg [n=70]) or placebo (n=71) for 12 months in a phase II, multicentre, double-blind study. Primary efficacy outcomes were the AD assessment scale cognitive subscale (ADAS-cog), the Alzheimer's Disease Cooperative Study activities of daily living scale (ADCS-ADL), and the clinical dementia rating sum of boxes (CDR-sb). In a 12-month extended treatment phase, patients who had received tarenflurbil continued to receive the same dose, and patients who had received placebo were randomly assigned to tarenflurbil at 800 mg or 400 mg twice per day. Primary efficacy analyses were done by intention to treat. This trial is registered with Health Canada (084527) and the Medicines and Healthcare products Regulatory Agency in the UK (20365/0001/A 69316). FINDINGS: A prespecified interaction analysis revealed that patients with mild AD (baseline MMSE 20-26) and moderate AD (baseline MMSE 15-19) responded differently to tarenflurbil in the ADAS-cog and the ADCS-ADL (p>or=0.10); therefore, these groups were analysed separately. Patients with mild AD in the 800 mg tarenflurbil group had lower rates of decline than did those in the placebo group in activities of daily living (ADCS-ADL difference in slope 3.98 [95% CI 0.33 to 7.62] points per year, effect size [reduction from placebo decline rate] 46.4%, Cohen's d 0.45; p=0.033) and global function (CDR-sb difference -0.80 [-1.57 to -0.03] points per year, effect size 35.7%, Cohen's d 0.42; p=0.042); slowing of cognitive decline did not differ significantly (ADAS-cog difference -1.36 [-4.07 to 1.36] points per year, effect size 33.7%, Cohen's d 0.20; p=0.327). In patients with moderate AD, 800 mg tarenflurbil twice per day had no significant effects on ADCS-ADL and ADAS-cog and had a negative effect on CDR-sb (-52%, Cohen's d -1.08; p=0.003). The most common adverse events were diarrhoea (in seven, nine, and five patients in the 800 mg, 400 mg, and placebo groups, respectively), nausea (in seven, seven, and four patients), and dizziness (in five, nine, and four patients). Patients with mild AD who were in the 800 mg tarenflurbil group for 24 months had lower rates of decline for all three primary outcomes than did patients who were in the placebo group for months 0-12 and a tarenflurbil group for months 12-24 (all p<0.001), and had better outcomes than did patients who were in the placebo group for months 0-12 and the 800 mg tarenflurbil group for months 12-24 (all p<0.05). INTERPRETATION: 800 mg tarenflurbil twice per day was well tolerated for up to 24 months of treatment, with evidence of a dose-related effect on measures of daily activities and global function in patients with mild AD. FUNDING: Myriad Pharmaceuticals.

Safety, tolerability, pharmacokinetics, and Abeta levels after short-term administration of R-flurbiprofen in healthy elderly individuals.

To evaluate the safety and tolerability and pharmacokinetic properties of R-flurbiprofen (Tarenflurbil) in normal elderly individuals and to determine the effect of the drug on amyloid beta 42 (Abeta42) levels, we conducted a double-blind, placebo-controlled study of 48 healthy subjects aged 55 to 80. Three successive cohorts were randomized to doses of 400, 800, or 1600 mg/d, or placebo, given as 2 divided doses for 21 days. Blood and cerebrospinal fluid were collected for pharmacokinetic studies and measurement of Abeta levels at baseline and on day 21. R-flurbiprofen was well-tolerated at all 3 doses. The compound penetrated the blood-brain barrier in a dose-dependent manner. From baseline to 21 days, comparisons between study groups revealed no significant differences in changes of cerebrospinal fluid Abeta42 levels and no significant differences in changes of plasma Abeta42 levels at the time of trough drug level at 21 days of treatment. Further analysis of drug concentration-response for plasma samples showed that at the time of peak plasma concentration, higher plasma drug concentration was related to lower Abeta42 plasma levels (P=0.016). R-flurbiprofen had an excellent safety profile and showed dose-dependent central nervous system penetration. Exploratory analyses of plasma Abeta and peak drug levels suggested a short-term effect in plasma that warrants independent verification. The safety, tolerability, and pharmacokinetic profile of R-flurbiprofen in these older individuals support the ongoing studies of this compound in patients with Alzheimer disease.

The aryl propionic acid R-flurbiprofen selectively induces p75NTR-dependent decreased survival of prostate tumor cells.

Epidemiologic studies show that patients chronically consuming nonsteroidal anti-inflammatory drugs (NSAID) for arthritis exhibit a reduced incidence of prostate cancer. In addition, some NSAIDs show anticancer activity in vitro. NSAIDs exert their anti-inflammatory effects by inhibiting cyclooxygenase (COX) activity; however, evidence suggests that COX-independent mechanisms mediate decreased prostate cancer cell survival. Hence, we examined the effect of selected aryl propionic acid NSAIDs and structurally related compounds on the decreased survival of prostate cancer cell lines PC-3, DU-145, and LNCaP by induction of the p75(NTR) protein. p75(NTR) has been shown to function as a tumor suppressor in the prostate by virtue of its intracellular death domain that can initiate apoptosis and inhibit growth. The most efficacious compounds for induction of p75(NTR) and decreased survival, in rank-order, were R-flurbiprofen, ibuprofen, oxaprozin, fenoprofen, naproxen, and ketoprofen. Because R-flurbiprofen and ibuprofen exhibited the greatest efficacy, we examined their dose-dependent specificity of induction for p75(NTR) relative to other members of the death receptor family. Whereas treatment with R-flurbiprofen or ibuprofen resulted in a massive induction of p75(NTR) protein levels, the expression of Fas, p55(TNFR), DR3, DR4, DR5, and DR6 remained largely unchanged. Moreover, transfection of either cell line before R-flurbiprofen or ibuprofen treatment with a dominant negative form of p75(NTR) to antagonize p75(NTR) activity or p75(NTR) small interfering RNA to prevent p75(NTR) protein expression rescued both cell lines from decreased survival. Hence, R-flurbiprofen and ibuprofen selectively induce p75(NTR)-dependent decreased survival of prostate cancer cells independently of COX inhibition.

NSAIDs and enantiomers of flurbiprofen target gamma-secretase and lower Abeta 42 in vivo.

Epidemiologic studies demonstrate that long-term use of NSAIDs is associated with a reduced risk for the development of Alzheimer disease (AD). In this study, 20 commonly used NSAIDs, dapsone, and enantiomers of flurbiprofen were analyzed for their ability to lower the level of the 42-amino-acid form of amyloid beta protein (Abeta42) in a human H4 cell line. Thirteen of the NSAIDs and the enantiomers of flurbiprofen were then tested in acute dosing studies in amyloid beta protein precursor (APP) transgenic mice, and plasma and brain levels of Abeta and the drug were evaluated. These studies show that (a). eight FDA-approved NSAIDs lower Abeta42 in vivo, (b). the ability of an NSAID to lower Abeta42 levels in cell culture is highly predicative of its in vivo activity, (c). in vivo Abeta42 lowering in mice occurs at drug levels achievable in humans, and (d). there is a significant correlation between Abeta42 lowering and levels of ibuprofen. Importantly, flurbiprofen and its enantiomers selectively lower Abeta42 levels in broken cell gamma-secretase assays, indicating that these compounds directly target the gamma-secretase complex that generates Abeta from APP. Of the compounds tested, meclofenamic acid, racemic flurbiprofen, and the purified R and S enantiomers of flurbiprofen lowered Abeta42 levels to the greatest extent. Because R-flurbiprofen reduces Abeta42 levels by targeting gamma-secretase and has reduced side effects related to inhibition of cyclooxygenase (COX), it is an excellent candidate for clinical testing as an Abeta42 lowering agent.