18. Tecfidera

A recent patent loss could jeopardize growth for Biogen's Tecfidera. (Biogen)

: Biogen
2019 sales: $4.43 billion 
Projected 2026 sales: $3.38 billion 
Projected CAGR: -4%
Used for: multiple sclerosis

Few markets are hotter right than now than multiple sclerosis, where a stable of blockbuster drugs is engaged in all-out war for a sales advantage. One of those blockbusters, Biogen's Tecfidera had a claim to make for the MS lead, but an unfortunate ruling on the drug's patent could wipe that potential away. 

Tecfidera hit $4.43 billion in sales in 2019, its sixth year on the market. Evaluate Pharma forecast the drug could hit $3.38 billion in sales in 2026, but it's not clear whether analysts considered the drug's bad beat in federal court in June. 

In June, U.S. District Judge Irene Keeley said generics maker Mylan “demonstrated by clear and convincing evidence” that certain claims of Biogen’s '514 patent for Tecfidera are invalid for “lack of written description.” That patent was set  to expire in 2028, meaning the decision, if upheld, could wipe out years of blockbuster sales.

RELATED: Judge wipes out Biogen's Tecfidera patent protections in suit against Mylan

After the ruling, RBC Capital Markets analyst Brian Abrahams said an appeal could take about 12 months. In a note to clients before the decision, his team predicted a "clear advantage" in appeals court for the district court winner—meaning Mylan.

18. Tecfidera