Most MRI contrast agents leak out of blood vessels into the surrounding tissue within minutes, which limits how long a scanner has to image the vessels themselves. In the 1990s a small Cambridge, Massachusetts company, EPIX Medical (later EPIX Pharmaceuticals), developed a gadolinium agent that binds reversibly to albumin in the blood and therefore stays inside the vessels for about an hour. Its development code was MS-325; the generic name became gadofosveset trisodium.
What it was for
The long intravascular phase allowed high-resolution magnetic resonance angiography (MRA) of the aorta, the leg arteries and the carotids without the timing race of conventional agents, and the same injection could image several vascular territories. Clinical trials focused on peripheral arterial disease, where MRA competes with CT angiography and catheter angiography.
Approval and market
The European Medicines Agency approved the agent as Vasovist in 2005, marketed by Schering (later Bayer). The US Food and Drug Administration, after two rejections, approved it as Ablavar in December 2008 for MRA of aortoiliac disease; by then EPIX had licensed the US rights to Lantheus Medical Imaging. EPIX itself, which had merged with Predix Pharmaceuticals in 2006 and shifted toward drug discovery, ran out of money and was liquidated in 2009.
Withdrawal
Sales never justified the product. Faster scanners and improved conventional agents narrowed the advantage, CT angiography became cheaper and quicker, and from 2006 the discovery that gadolinium agents could cause nephrogenic systemic fibrosis in patients with kidney failure made radiologists cautious about all of them. Vasovist was withdrawn in Europe in 2011 and Ablavar was discontinued in the United States in 2017.
What is used now
Vascular MRI today uses standard extracellular gadolinium agents with fast multi-station techniques, non-contrast MRA sequences that need no injection at all, and, for some questions, ferumoxytol, an iron-oxide agent that behaves as a blood-pool agent and is used off-label. The idea behind MS-325 was sound; the timing and the economics were not.
This site is an independent medical reference and is not connected to the former EPIX companies or to any manufacturer.