9. Tecfidera

Multiple sclerosis
2015 sales: $3.64 billion
2020 sales projection: $5.56 billion

When Biogen ($BIIB) rolled out Tecfidera in April 2013, it was the third multiple sclerosis pill to hit the market after Novartis' ($NVS) Gilenya and Sanofi's ($SNY) Aubagio. No first-to-market advantage, but the much-anticipated drug quickly zoomed to first place among oral MS treatments--and notched blockbuster-pace earnings in 2013, with $873 million for its first eight-plus months on the market.

By 2014, Biogen was hiking its earnings projections as Tecfidera sales grew and the drug's route forward seemed clear. But in October 2014, Biogen reported the death of a Tecfidera patient suffering from progressive multifocal leukoencephalopathy (PML), a rare brain infection. The FDA added that information to the drug's official label the next month.

Still, Tecfidera ended the year with $2.9 billion in sales. But in July 2015, the company confirmed another PML case, this one non-fatal, in a patient using a compounded version of Tecfidera's active ingredient, dimethyl fumarate. Scientists followed up by urging doctors to closely monitor patients for PML risks and called for more research into the condition.

PML has cropped up in MS patients before, including those using Biogen's own Tysabri. Novartis' Gilenya, for instance, was tagged with its third PML case last August. Tecfidera sales didn't take off the way Biogen had anticipated last year, and flat script trends led the company to cut its forecast for the year

Growth slowed to the point where Biogen felt the need to cut 800 jobs and other costs to help fund a new marketing-and-education push for Tecfidera. The company replaced its commercial chief, Tony Kingsley, in mid-October. Meanwhile, it stepped up sales calls and rolled out a brand-new TV campaign. By the end of 2015's fourth quarter, the drug had racked up $993 million in sales for the period, a 16% increase year-over-year. Full-year sales amounted to $3.6 billion, 19% growth over 2014.

"We are seeing positive leading indicators for the recently launched marketing campaign for Tecfidera, including increased visits to our website and higher call volume into our patient services organization," CFO Paul Clancy said during the company's Q4 earnings call. No doubt Biogen hopes the buzz continues. Analysts seem to think that the drug can weather any safety worries, with an average prediction of $6.8 billion by 2020. -- Tracy Staton (email | Twitter)

For more:
Biogen sees new Tecfidera buzz as DTC, marketing push kicks in
FDA adds PML death scenario to Tecfidera label
Bad news for Biogen: Tecfidera sales trend flat in Q3, analyst says
Biogen's Tecfidera faces new challenge as scientists call for brain infection monitoring
Biogen gets beaten up as slowing Tecfidera sales lead it to trim forecast
Biogen confirms second PML case among Tecfidera patients

9. Tecfidera