Drug development for exceptionally rare metabolic diseases: challenging but not impossible.

BACKGROUND: We studied to what extent the level of scientific knowledge on exceptionally rare metabolic inherited diseases and their potential orphan medicinal products is associated with sponsors deciding to apply for an orphan designation at the US Food and Drug Administration (FDA) or the European Medicines Agency (EMA). METHODS: All metabolic diseases with a genetic cause and prevalence of less than 10 patients per 1 million of the population were selected from the 'Orphanet database of Rare diseases'. The outcome of interest was the application for an orphan designation at FDA or EMA. The level of publicly available knowledge of the disease and drug candidate before an orphan designation application was defined as whether the physiological function corresponding with the pathologic gene and initiation of the pathophysiological pathway was known, whether an appropriate animal study was identified for the disease, whether preclinical proof of concept was ascertained and the availability of data in humans. Other determinants included in the study were metabolic disease class, the prevalence of the disease, prognosis and time of first description of the disease in the literature. Univariate relative risks (RRs) and 95% confidence intervals (CIs) of an orphan designation application were calculated for each of these determinants. In addition, a multivariate Cox regression analysis was conducted (Forward LR). RESULTS: In total, 166 rare metabolic genetic diseases were identified and included in the analysis. For only 42 (25%) of the diseases an orphan designation application was submitted at either FDA or EMA before January 2012. The multivariate analysis identified preclinical proof of concept of a potential medicinal product as major knowledge related determinant associated with an orphan designation application (RRadj 3.9, 95% CI 1.9-8.3) and confirmed that prevalence of the disease is also associated with filing an application for an orphan designation (RRadj 2.8, 95% CI 1.4-5.4). CONCLUSION: For only one out of four known exceptionally rare metabolic inherited diseases sponsors applied for an orphan designation at FDA or EMA. These applications were found to be associated with the prevalence of the rare disease and the level of available scientific knowledge on the proof of concept linking possible drug candidates to the disease of interest.

Regulatory scientific advice on non-inferiority drug trials.

The active-controlled trial with a non-inferiority design has gained popularity in recent years. However, non-inferiority trials present some methodological challenges, especially in determining the non-inferiority margin. Regulatory guidelines provide some general statements on how a non-inferiority trial should be conducted. Moreover, in a scientific advice procedure, regulators give companies the opportunity to discuss critical trial issues prior to the start of the trial. The aim of this study was to identify potential issues that may benefit from more explicit guidance by regulators. To achieve this, we collected and analyzed questions about non-inferiority trials posed by applicants for scientific advice in Europe in 2008 and 2009, as well as the responses given by the European Medicines Agency (EMA). In our analysis we included 156 final letters of advice from 2008 and 2009, addressed to 94 different applicants (manufacturers). Our analysis yielded two major findings: (1) applicants frequently asked questions 'whether' and 'how' to conduct a non-inferiority trial, 26% and 74%, respectively, and (2) the EMA regulators seem mainly concerned about the choice of the non-inferiority margin in non-inferiority trials (36% of total regulatory answers). In 40% of the answers, the EMA recommended using a stricter margin, and in 10% of the answers regarding non-inferiority margins, the EMA questioned the justification of the proposed non-inferiority margin. We conclude that there are still difficulties in selecting the appropriate methodology for non-inferiority trials. Straightforward and harmonized guidance regarding non-inferiority trials is required, for example on whether it is necessary to conduct such a trial and how the non-inferiority margin is determined. It is unlikely that regulatory guidelines can cover all therapeutic areas; therefore, in some cases regulatory scientific advice may be used as an opportunity for tailored advice.

Determinants for successful marketing authorisation of orphan medicinal products in the EU.

In 2010, the European Regulation for Orphan Medicinal Products (OMPs) was in force for ten years. In this study we assessed possible determinants of applications for OMPs in the EU since 2000 that are associated with a successful marketing authorisation. Our analysis shows that clinical trial characteristics such as demonstrating convincing evidence of a beneficial effect on the primary endpoint, the selection of a clinically relevant endpoint, providing RCT data as pivotal study evidence and the submission of sound dose finding data are critical success factors. In addition, high medical need seems to counterweigh uncertainties about the scientific evidence in the benefit-risk assessment of OMPs.

Regulatory scientific advice in drug development: does company size make a difference?

PURPOSE: To assess whether the content of Scientific Advice (SA) questions addressed to a national drug regulatory agency is associated with company size. This may help to increase understanding about the knowledge, strategic, and regulatory gaps companies face during drug development. METHODOLOGY: A cross-sectional analysis was performed of SA provided by the Dutch Medicines Evaluation Board (MEB) in 2006-2008. Definition of company size was based on ranking by total revenues (Scrip's Pharmaceutical Company League Tables 2008). The content of each SA question was scored according to predefined domains (quality, nonclinical, clinical, regulatory, and product information), their subdomains (e.g., efficacy), and a selection of additional content variables (e.g., endpoints, choice of active comparator). RESULTS: In total, 201 SA documents including 1,087 questions could be identified. Small, medium-sized, and large companies asked for SA 110 (54.7%), 40 (19.9%), and 51 (25.4%) times, respectively. Clinical questions were asked most often (65.9%), mainly including efficacy (33.2%) and safety questions (24.0%). The most frequent topics were overall efficacy and safety strategy. Small companies asked quality and nonclinical questions more often (P < 0.001) and clinical questions less frequently than large companies (P = 0.004). Small companies asked significantly more clinical questions about pharmacokinetics, including bioequivalence, than medium-sized and large companies (P < 0.001). CONCLUSION: The array of topics addressed in SA provides an interesting outlook on what industry considers to be still unresolved in drug development and worthwhile to discuss with regulators. Company size is associated with the content of SA questions. MEB advice accommodates both innovative and noninnovative drug development.