12. Prolia/Xgeva

Amgen has weathered some costly patent expirations in recent years, but for now, it should be clear. Other expirations approach in the middle of the decade. (Amgen)

2020 sales: $4.6 billion 
Key patent expirations: 2025 to 2026 

Amgen is no stranger to costly patent cliffs. In 2019, after losing exclusivity on white blood cell booster Neulasta and anemia med Epogen the prior year, the company posted a 2% revenue decline to $23.4 billion. Amgen turned things around last year, growing sales a healthy 9% from 2019 despite pandemic challenges.

Now, with a few years free from large patent exclusivity losses, the company is expected to enter a stretch of growth driven by newer meds, including migraine drug Aimovig and newly approved cancer med Lumakras.  

That’ll likely change later this decade as the company faces expected patent losses on bone drugs Prolia and Xgeva, which together generated $4.66 billion last year. The meds, which share the same active ingredient, denosumab, are used to improve or protect bone health in patients with osteoporosis or those undergoing various cancer treatments. 

RELATED: The top 15 drug patent expirations of 2018 — Neulasta — Epogen 

Amgen lists the patent expirations on denosumab between 2021 and 2025, according to the drugmaker’s annual filing

A host of companies including Novartis’ Sandoz are working on copycats. That drugmaker's biosimilar is in a phase 3 trial, which is expected to wrap up in July 2022. Among the other companies working on denosumab copycats are Samsung Bioepis and Taiwan’s JHL Biotech.  

RELATED: Surprise! Amgen's hot KRAS drug seals early FDA approval, winning a shot against 'undruggable' cancer 

For Amgen, a multibillion-dollar loss of exclusivity is a big deal. The company generated $25.4 billion last year, meaning the Prolia and Xgeva revenues represented about 18% of the total. As the patent expirations near, the company will surely be looking to grow sales for newer meds to ease the patent cliff pain.

One such new med, the 2019 osteoporosis launch Evenity, posted 85% growth last year to $350 million. Biosimilars are also on the upswing at the company, and Repatha is gaining steam after a 2019 price cut on the drug.

Meanwhile, Lumakras just scored an FDA approval in certain patients with non-small cell lung cancer in May. Analysts believe the drug will pull in around $100 million this year and that sales could reach into the billions of dollars at peak.

12. Prolia/Xgeva