9. Ibrance

Pfizer is suing several developers of generics to its breast cancer drug Ibrance. (Pfizer)

Company: Pfizer
2020 sales: $5.39 billion
Key patent expiration: 2027

Even as headlines center on Pfizer's COVID-19 vaccine efforts, breast cancer drug Ibrance has been a key blockbuster for the drug giant for years. Pfizer doesn't expect the drug to lose U.S. exclusivity until 2027, but that's not stopping generic drugmakers from making plans for their copycats.

Back in 2019, multiple generic drugmakers notified Pfizer that they had filed for copycat approvals, arguing that two key patents on the drug are invalid. One of the patents at issue recently scored a four-year extension to 2027, while the drug’s crystalline form patent, which expires in 2034, is also under challenge.

In response, Pfizer has sued generics companies in various federal courts, Pfizer said in a recent securities filing. These include two suits against Aurobindo Pharma and Dr. Reddy’s Laboratories.

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As the lead asset in Pfizer’s oncology portfolio and a growth driver for the entire company, Ibrance is an important brand that Pfizer aims to protect. The med brought in $5.39 billion in 2020 sales, up 9% year over year.

Lately, though, the drug has been under pressure from Novartis’ Kisqali and Eli Lilly’ Verzenio. And a spate of trial flops in previously treated HR-positive, HER2-negative metastatic breast cancer and postsurgery use haven't eased analysts' concerns. SVB Leerink analyst Geoffrey Porges, for example, suspected there would be some “spillover” effect from Ibrance's adjuvant failures that would hurt its uptake in the current metastatic setting.

Ibrance recorded a 7% sales decline in the first quarter of 2021, but Pfizer attributed the slip to increased enrollment in the drug’s patient assistance program as patients suffer from COVID-19-related economic hardships. The drug was still the clear leader in the CDK class with an 84% share of scripts in first-line use, Pfizer CEO Albert Bourla said on a call in May. 

RELATED: The top 20 drugs by worldwide sales in 2020 | 13. Ibrance

Elsewhere in the company’s oncology franchise, Astellas-partnered prostate cancer drug Xtandi has been posting revenue increases, and Merck KGaA-shared PD-L1 inhibitor Bavencio has been adding new indications. Beyond those marketed offerings, the group's late-stage pipeline looks thin.

To beef up its oncology portfolio, Pfizer bought cancer specialist Array BioPharma for $11.4 billion in 2019. On the deal-making front, Pfizer is aiming to ensure durable growth in the second part of the decade, Bourla told investors on the Q1 call in May.

“You should expect to see a lot of phase 2, phase 3 business development deals that will allow us to bring in-house a lot of potential medicines that could become medicines in this time frame,” he said.

9. Ibrance