Letters Section Editor: Stephen J. Lurie,
MD, PhD, Senior Editor.
To the Editor: Dr Nissen and colleagues1 reported that 5 weeks of treatment with intravenous
recombinant ApoA-I Milano–phospholipid complexes (ETC-216) resulted
in an average of 4.2% reduction in the volume of coronary atheroma. We disagree,
however, with their speculation that this benefit is related to dimerization
of high-density lipoprotein (HDL) and improved reverse cholesterol transport.
In fact, the HDL pattern of individuals with the ApoA-I Milano variant has
been shown to consist primarily of the smaller HDL-3 particles with a nearly
total absence of the larger HDL-2 particles.2 Consequently,
the infusion of ApoA-I Milano is likely to generate HDL-3 rather than HDL-2
particles. The misconception regarding the term dimerization may originate from the finding that ApoA-I Milano is indeed capable
of giving rise to ApoA-I dimers while the size of the resultant HDL particles
on lipidation remains small.1
Kim H, Jacobson EL, Jacobson MK, Lacko AG. ApoA-1 Milano and Regression of Atherosclerosis. JAMA. 2004;291(11):1319-1320. doi:10.1001/jama.291.11.1319-a