Thursday, May 1, 2008

Safety First: Two Gene Transfer Studies Against Blindness

...continued from previous post:  The preclinical studies supporting these human trials are about as good as it ever gets in translational research: numerous large animals (dogs) were treated effectively, and their vision in treated eyes seems to have been restored out to as much as eight years.

The NEJM papers report delivering nearly identical vectors to one eye of volunteers with Leber's Congenital Amaurosis type 2 (LCA2). The U.K. group did not observe any clinically "significant improvement in visual acuity," though one of the three volunteers showed some improved retinal function. The U.S. group (based at the University of Pennsylvania) shows significant improvement using an ostensibly objective measure– the pupillary light reflex. The authors also claim all three volunteers had improved visual acuity.

Importantly, neither group reported any adverse events attributable to the gene transfer product.  No immune response to the transgene was detected in sera.  Immune response to vector was detected in only one instance– and only transiently. Importantly, no vector was detected outside the eye. Thus, the vector does not appear to present any really big, extremely common, and almost immediate safety concerns.  All good. (to be continued... photo credit: lu lacerda 2007)

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