Sanofi’s MS Pill Aubagio Wins FDA Approval
Another pill for multiple sclerosis has gotten FDA’s stamp of approval. Sanofi’s Aubagio is expected to hit the market in a few weeks, making it only the second oral drug available to people with MS. Novartis’ MS pill Gilenya, which works by a different mechanism of action than Aubagio, has been on the market for two years.
Aubagio will cost roughly $45,000 a year, strategically priced below the leading MS drugs on the market. As Leerink Swann analyst Seamus Fernandez pointed out today in a note, that puts it at about 6.5% lower than Teva’s Copaxone, 8% less than Biogen Idec’s Avonex, and 28% below the price of Gilenya. “We continue to be surprised by the magnitude of price increases within the MS market overall and view Sanofi’s slight discount as reasonable,” he added.
As we described back in 2009, MS is a problem of an immune system gone awry, with lymphocytes first attacking myelin, the protective sheath on nerve fibers, and eventually breaking down the fibers themselves. The first wave of MS drugs—beta-interferons like Avonex and Copaxone–intercept T-cells to slow down the body’s immune response. But that approach is promiscuous—the beta-interferons also prompt widespread gene expression, and cause flu-like side effects.
The latest wave of MS treatments take a more refined approach to reining in the immune system. Biogen’s Tysabri, for example, blocks alpha-4-beta-1 integrin, which signals immune cells to leave the bloodstream and enter the brain and spinal cord. Gilenya keeps some T-cells out of the bloodstream by binding to sphingosine-1-phosphate receptor, thereby preventing some white blood cells from leaving the lymph nodes. Aubagio, meanwhile, inhibits dihydroorotate dehydrogenase, a critical enzyme in the synthesis of pyrimidine, which activated white blood cells need to survive. Whereas the beta-interferons have a sweeping effect on the immune system, some pathways are maintained with Aubagio’s activity.
Aubagio has a few advantages over Gilenya and Tysabri: namely, it does not carry the same safety risks associated with those drugs (see here and herefor more on that), and is taken orally just once a day.
But Aubagio also has its downsides. On the efficacy front, its milder interaction with the immune system renders it less effective than the more hard-hitting treatments. And it can cause hair loss and birth defects, a serious limitation for women of childbearing age—as Fernandez points out in his note, a large population in the MS community.