6. Avastin

2015 sales: $6.95 billion
2020 projection: $6.36 billion

Roche ($RHHBY) has been milking everything it can from Avastin since winning approval for the drug to treat colon cancer a decade ago, pushing for label indications to rake in stellar sales. In August 2014, the company nabbed an FDA OK to use its med to treat cervical cancer. A few months later, the agency signed off on Avastin in combination with chemotherapy as a treatment for platinum-resistant ovarian cancer, delivering another win to the Swiss drugmaker. The drug already had indications in breast, lung and kidney cancers.

Roche's hard work appears to be paying off. In 2014, the Basel-based drugmaker saw Avastin sales shoot up 6% on the heels of regulatory blessings, adding some extra padding to its top-line haul. And last year, the drug delivered a 9% increase to 6.68 billion Swiss francs, or about $6.95 billion.

Still, things haven't been all smooth sailing for Roche with Avastin--especially in tight-fisted European countries. The U.K.'s National Institute for Health and Care Excellence (NICE), has taken some shots at Avastin, restricting its use in the country on cost-effectiveness grounds. Patients can still access the drug through England's Cancer Drugs Fund, which covers treatments that NICE rejects. But the fund recently announced that it would "de-list" some of its covered meds in an effort to cut costs, and some say Avastin could be the next to go. -- Emily Wasserman (email | Twitter)

For more:
European pharma lobby says 'non' to French funding for off-label Avastin
Roche nabs EU approval for Avastin for cervical cancer
Roche's Avastin wins FDA green light in ovarian cancer
Study: Roche's cheaper Avastin just as safe as Lucentis in eye disease
Roche's Avastin nabs quick FDA nod for cervical cancer use

6. Avastin