Covariate effects have a limited impact on tPDE4i. There was a general association between tPDE4i and the occurrence of common AEs in patients with COPD.

BackgroundThe oral selective phosphodiesterase-4 inhibitor roflumilast (ROF) reduces exacerbations in patients with severe COPD. Adverse events (AEs) can cause early ROF discontinuation. Alternative dosing strategies may help patients continue their therapy.MethodsIn this multicenter, double-blind trial, 1,321 patients with severe COPD were randomized 1:1:1 to 4 weeks’ treatment with ROF 250 µg once daily (OD), 500 µg every other day (EOD), or 500 µg OD, each followed by ROF 500 µg OD for 8 weeks, plus standard therapy. The primary end point was the percentage of patients prematurely discontinuing study treatment.ResultsPatients in the 250 µg OD/500 µg OD group had significantly fewer treatment discontinuations (odds ratio [OR] 0.66 [95% CI 0.47–0.93], p=0.017) and lower rates of AEs of interest such as diarrhea, nausea, headache, decreased appetite, insomnia and abdominal pain (OR 0.63 [95% CI 0.47–0.83], p=0.001) compared with those in the 500 µg OD group. Although rates of discontinuation and AEs of interest were numerically lower with ROF 500 µg EOD/500 µg OD, the difference was not significant (OR 0.76, p=0.114, and OR 0.78, p=0.091, respectively) compared with ROF 500 µg OD.ConclusionA dose of ROF 250 µg OD for 4 weeks before escalation to the approved maintenance dose of 500 µg OD resulted in reduced treatment discontinuation and improved tolerability.

Prion diseases are neurodegenerative diseases associated with the accumulation of a pathogenic isoform of the host-encoded prion protein. The cellular responses to prion infection are not well defined. By performing microarray analysis on cultured neuronal cells infected with prion strain 22L, in the group of up-regulated genes we observed predominantly genes of the cholesterol pathway. Increased transcript levels of at least nine enzymes involved in cholesterol synthesis, including the gene for the rate-limiting hydroxymethylglutaryl-CoA reductase, were detected. Up-regulation of cholesterogenic genes was attributable to a prion-dependent increase in the amount and activity of the sterol regulatory element-binding protein Srebp2, resulting in elevated levels of total and free cellular cholesterol. The up-regulation of cholesterol biosynthesis appeared to be a characteristic response of neurons to prion challenge, as cholesterogenic transcripts were also elevated in persistently infected GT-1 cells and prion-exposed primary hippocampal neurons but not in microglial cells and primary astrocytes. These results convincingly demonstrate that prion propagation not only depends on the availability of cholesterol but that neuronal cells themselves respond to prions with specific up-regulation of cholesterol biosynthesis.

PurposeClinical Trial Simulations (CTS) are a valuable tool for decision-making during drug development. However, to obtain realistic simulation scenarios, the patients included in the CTS must be representative of the target population. This is particularly important when covariate effects exist that may affect the outcome of a trial. The objective of our investigation was to evaluate and compare CTS results using re-sampling from a population pool and multivariate distributions to simulate patient covariates.MethodsCOPD was selected as paradigm disease for the purposes of our analysis, FEV1 was used as response measure and the effects of a hypothetical intervention were evaluated in different populations in order to assess the predictive performance of the two methods.ResultsOur results show that the multivariate distribution method produces realistic covariate correlations, comparable to the real population. Moreover, it allows simulation of patient characteristics beyond the limits of inclusion and exclusion criteria in historical protocols.ConclusionBoth methods, discrete resampling and multivariate distribution generate realistic pools of virtual patients. However the use of a multivariate distribution enable more flexible simulation scenarios since it is not necessarily bound to the existing covariate combinations in the available clinical data sets.Electronic supplementary materialThe online version of this article (doi:10.1007/s11095-015-1699-x) contains supplementary material, which is available to authorized users.

Reduction of roflumilast dose in the first few weeks of therapy may be able to reduce the incidence of treatment-related AEs. Clearly, modeling provides only the basis for hypothesis generation, and must be supported with clinical evidence from carefully designed trials.