The ideal model in atherosclerosis and dyslipidaemia – does it exist?

Phospholipase A2 inhibitors in the treatment of atherosclerosis: a new approach moves forward in the clinic

Phase II results of the trials of two phospholipase A2 inhibitors which may be of value in the treatment of atherosclerosis and cardiovascular disease have been reported in the past year. Darapladib (GlaxoSmithKline) is an inhibitor of lipoprotein-associated phospholipase A2 and varespladib (Anthera) inhibits several forms of the secreted phospholipase A2s. Despite the apparent similarity of mechanism, which is also built into the compounds' names, the role of the two types of phospholipase in atherogenesis is very different. Evidence for this comes from a range of preclinical studies and from epidemiological data which are summarised here. These data provide a basis for the Phase II studies and support decisions to move into Phase III, a decision which in the case of darapladib has been made and studies commenced (STABILITY trial). For varespladib the FRANCIS-ACS trial in acute coronary syndrome patients is in progress.

Selective thyromimetics for atherosclerosis and dyslipidaemia: another old target making progress

BACKGROUND

Whereas many new targets for drug discovery have been identified from new biology, such as that from the Human Genome Project, some targets have been known for decades but have not been exploited.

OBJECTIVE

One such target, selective thyromimetics, is reviewed from a historical perspective and in the light of recent developments.

METHODS

The history of thyromimetics in atherosclerosis and dyslipidaemia is reviewed as the background to the recent publication of the first human data on a new selective thyromimetic, KB-2115 (eprotirome).

CONCLUSION

The published data provide proof of concept/mechanism, opening the way to larger studies in a wider range of subjects and in combination with statins.

The continuing complexities of high-density lipoprotein metabolism in drug discovery and development

The termination of the Phase III clinical trial of Pfizer's CETP inhibitor torcetrapib, Investigation of lipid level management to understand its impact in atherosclerotic events (ILLUMINATE), due to excess mortality in the treatment group raised many questions for those involved in the discovery and development of drugs targeting high-density lipoprotein and of atherosclerosis in general. Although the reasons for the failure of torcetrapib are still not known, some of the consequences for the wider field are already apparent. Several imaging studies with torcetrapib showed no change in the various measures of lesion size, which gave some confidence in the interpretation of such studies. Although the case for raising high-density lipoprotein is strong and widely accepted, there will be a much closer interrogation of drugs targeting new mechanisms that will result in longer development times. In the meantime, existing drugs which modify high-density lipoprotein are being revisited, particularly niacin. This editorial commentary briefly discusses these and related issues from the perspective of 6 months following the termination of ILLUMINATE.

Drug discovery in the metabolic syndrome: context and some recent developments

The metabolic syndrome, encompassing the clinically distinct but related areas of dyslipidaemia, insulin resistance, obesity and vascular disease, offers a wide arena for drug discovery. There is substantial and growing unmet medical need, particularly as the worldwide epidemic of obesity continues to develop. There are also many targets and biological mechanisms that can be exploited. However, the context for clinical development is challenging because of the many ways in which the syndrome can be approached. As with most therapeutic areas, preclinical data provide only limited confidence in the potential of a novel target in humans. In this review, the author outlines the context for drug discovery in the metabolic syndrome, the clinical and biological scope and recent developments in preclinical models. Finally, existing examples of drug targets for a range of biological mechanisms are considered, outlining their biology and points relevant to lead identification and optimisation and clinical development.