5. Eylea

Regeneron's Eylea is hoping to beat out highly touted challenger Beovu from Novartis. (Regeneron)

Companies: Regeneron, Bayer
2019 sales: $7.99 billion
Projected 2026 sales: $6.68 billion
Projected CAGR: -3%
Used for: wet age-related macular degeneration, diabetic macular edema, diabetic retinopathy, macular edema

Regeneron and Bayer's bestselling eye drug Eylea has taken the wet age-related macular degeneration market by storm in recent years. But a serious challenger in Novartis' Beovu is hoping to chip away at Eylea's lead. 

Eylea posted $7.99 billion in sales in 2019 and could see a slight 3% decline in sales through 2026 as Beovu siphons off market share, Evaluate Pharma reported. That would leave Regeneron and Bayer's med with $6.68 billion in sales that year. 

It might have been worse. Beovu presented an existential challenge of sorts for Eylea when it was approved in October, but a safety warning for the drug may hinder Novartis' ability to give the older med a run for its money. 

RELATED: 'Lightning struck': How a safety alert shifted doctor sentiment on Novartis' Beovu

5. Eylea