David M. L. Morgan

Inhibition of ornithine decarboxylase potentiates nitric oxide production in LPS-activated J774 cells

We have examined whether modulation of the polyamine biosynthetic pathway, through inhibition by α‐difluoromethylornithine (DFMO) of the rate limiting enzyme, ornithine decarboxylase (ODC), modulates NO synthesis in J774 macrophages. DFMO potentiated LPS‐stimulated nitrite production in both a concentration‐ and time‐dependent manner, increasing nitrite levels by 48±5% at 10 mm. This effect was observed in cells pre‐treated with DFMO for 24 h prior to stimulation with LPS. Addition of DFMO 12 h after LPS failed to potentiate LPS‐induced nitrite production. Supplementation of the culture medium with horse serum (10%) in place of foetal calf serum (10%) caused no significant change in either LPS‐induced nitrite production or in the ability of DFMO (10 mm) to potentiate LPS‐induced NO synthesis. Metabolism of L‐[3H]arginine to L‐[3H]citrulline by partially purified inducible nitric oxide synthase (iNOS) was not significantly altered by either DFMO (1–10 mm) or by putrescine (0.001–1 mm), spermidine (0.001–1 mm) or spermine (0.001–1 mm). iNOS activity was also unaffected by 1 mM EGTA but was markedly attenuated (70±0.07%) by L‐NMMA (100 μm). Pre‐incubation of cells with DFMO (10 mm; 24 h) prior to activation with LPS resulted in enhanced (∼2 fold) iNOS protein expression. These results show that DFMO potentiates LPS‐induced nitrite production in the murine macrophage cell line J774. Since the only known mechanism of action of DFMO is inhibition of ODC, and thus polyamine biosynthesis, we conclude that expression of iNOS can be critically regulated by endogenous polyamines.

The International Conference on Harmonization Guideline “Statistical Principles for Clinical Trials”: Issues in Applying the Guideline in Practice

The International Conference on Harmonization (ICH) guideline “Statistical Principles for Clinical Trials” was adopted by the Committee for Proprietary Medicinal Products in March 1998, and consequently is operational in Europe. In October 1998 a one-day discussion forum was held in London by Statisticians in the Pharmaceutical Industry (PSI). The aim of the meeting was to discuss how statisticians were responding to some of the issues in the guideline, and to document consensus views where they existed. The forum was attended by industrial, academic, and regulatory statisticians. This paper outlines the questions raised, resulting discussions, and consensus views reached.

EFSPI/PSI working group on data sharing: accessing and working with pharmaceutical clinical trial patient level datasets - a primer for academic researchers.

BackgroundAccess to patient level datasets from clinical trial sponsors continues to be an important topic for the Pharmaceutical Industry as well as academic institutions and researchers. How to make access to patient level data actually happen raises many questions from the perspective of the researcher.MethodsPatient level data access models of all major pharmaceutical companies were surveyed and recommendations made to guide academic researchers in the most efficient way through the process of requesting and accessing patient level data.ResultsThe key considerations for researchers covered here are finding information; writing a research proposal to request data access; the review process; how data are shared; and the expectations of the data holder. A lot of clinical trial information is available on public registries and so these are great sources of information. Depending on the research proposal the required information may be available in Clinical Study Reports and therefore patient level data may not need to be requested. Many data sharing systems have an electronic form or template but in cases where these are not available the proposal needs to be created as a stand-alone document outlining the purpose, statistical analysis plan, identifying the studies for which data are required, the research team members involved, any conflicts of interest and the funding for the research.There are three main review processes - namely having an internal review board, external review board selected by the data holder or an external review board selected by a third party. Data can be shared through Open access i.e. on a public website, direct sharing between the data holder and the researcher, controlled access or the data holder identifies a contract organization to access the data and perform the analyses on behalf of the researcher. The data that are shared will have accompanying documentation to assist the researcher in understanding the original clinical trial and data collection methods. The data holder will require a legally binding data sharing agreement to be set up with the researcher. Additionally the data holder may be available to provide some support to the researcher if questions arise.ConclusionWhilst the benefits and value of patient level data sharing have yet to be fully realised, we hope that the information outlined in this article will encourage researchers to consider accessing and re-using clinical trial data to support their research questions.

Estimands: discussion points from the PSI estimands and sensitivity expert group

ICH E9 Statistical Principles for Clinical Trials was issued in 1998. In October 2014, an addendum to ICH E9 was proposed relating to estimands and sensitivity analyses. In preparation for the release of the addendum, Statisticians in the Pharmaceutical Industry held a 1-day expert group meeting in February 2015. Topics debated included definition, development, implementation, education and communication challenges associated with estimands and sensitivity analyses. The topic of estimands is an important and relatively new one in clinical development. A clear message from the meeting was that estimands bridge the gap between study objectives and statistical methods. When defining estimands, an iterative process linking trial objectives, estimands, trial design, statistical and sensitivity analysis needs to be established. Each objective should have at least one distinct estimand, supported by sensitivity analyses. Because clinical trials are multi-faceted and expensive, it is unrealistic to restrict a study to a single objective and associated estimand. The actual set of estimands and sensitivity analyses for a study will depend on the study objectives, the disease setting and the needs of the various stakeholders. Copyright