Future Challenges for Microsomal Transport Protein Inhibitors

Atherosclerosis is a leading cause of morbidity and mortality worldwide. Statins are established as first choice drugs for the management of hyperlipidaemia and cardiovascular risk. However, a residual cardiovascular risk, partially attributable to lipids, remains even after statin treatment. This risk appears to be associated with both high-density lipoprotein cholesterol and triglyceride lipid fractions. Several novel therapeutic approaches have been proposed to reduce lipid levels. Microsomal transfer protein (MTP) is involved in the assembly of very-low-density lipoprotein and chylomicron lipoprotein particles in the liver and the gut, respectively. In the preclinical setting, various agents that affect activity of MTP have shown that inhibition can result in profound reductions in blood triglycerides and cholesterol. Similarly, evidence of efficacy using the target has been confirmed in man with small molecule inhibitors and antisense oligonucleotides. Unfortunately, despite their efficacy in reducing lipids, the clinical utility of small molecule inhibitors has been restricted by their potential to induce hepatic steatosis. Continuing attempts to utilise this clinical target (to decrease cholesterol, triglycerides and weight) have involved the use of lower doses or non-systemically absorbed MTP inhibitors.