Growth drugs outpace a steep patent cliff
- Amgen reported total second quarter revenues exceeding $10 billion, up 10% year over year.
- The 6 key growth drivers grew 26% in the second quarter of 2026.
- Prolia and XGEVA sales fell 33% year over year to $1.1 billion as copycat biologic drugs took market share.
- Management raised 2026 revenue guidance to a range of $38.2 billion to $39.4 billion following a strong second quarter.
- The MariTide obesity program expanded to 12 Phase 3 trials, testing monthly or quarterly dosing.
New drugs absorb the biosimilar shock
Amgen is successfully navigating a major handoff year. Older bone drugs Prolia and XGEVA are losing patent protection, and biosimilars are now taking share. In the second quarter of 2026, that franchise dropped 33% year over year to $1.1 billion.
The good news is that the rest of the portfolio is growing fast enough to cover the loss. Amgen reported total second quarter revenues exceeding $10 billion, up 10% year over year. Its 6 key growth drivers grew 26% in aggregate. That strong execution prompted management to raise full-year 2026 revenue guidance to between $38.2 billion and $39.4 billion.
The stock relies on a balanced setup. Repatha, EVENITY, TEZSPIRE, rare disease drugs, oncology drugs, and biosimilars must keep the company growing while Prolia and XGEVA continue their decline. Innovative oncology is also helping, with IMDELLTRA sales surging 115% year over year and reaching over 2,000 U.S. accounts.
MariTide could change the entire story if it works. Amgen is betting heavily on this obesity drug, expanding to 12 Phase 3 trials. The goal is to prove patients can take it once a month or once a quarter instead of weekly. That convenience could matter, but the drug still has to compete on weight loss, safety, and staying power against entrenched weekly competitors.
Patents, factories, and drug sales
Amgen makes money by selling prescription medicines to wholesalers, distributors, and health systems. Most products are biologics, which are drugs made from living cells. They are hard to copy, but once patents expire, biosimilars can pressure both volume and price.
The moat comes from research skill, patents, clinical data, and large-scale biologic manufacturing. A drug company also needs payer access, which means insurance plans and government programs must agree to cover the medicine at a usable price.
The model can break in three main ways. A major drug can lose exclusivity faster than expected. A pipeline drug can fail in trials. Or payers and governments can force lower net prices, which is already a risk for Otezla under Medicare price setting beginning in 2027.
Amgen is also trying a more direct model in the U.S. The AmgenNow platform started with Repatha, aiming to make access simpler and more affordable for patients.
What sells, what could grow
Repatha
Repatha is a cholesterol-lowering drug and one of Amgen's strongest growth drivers. Sales grew 37% year over year in the second quarter of 2026.
EVENITY
EVENITY treats osteoporosis and helps offset the Prolia decline. It grew 38% year over year in the second quarter.
TEZSPIRE
TEZSPIRE treats severe asthma and showed exceptional momentum, growing 42% year over year in the second quarter of 2026.
IMDELLTRA
A key piece of the innovative oncology portfolio, IMDELLTRA sales surged 115% year over year in the second quarter.
Prolia and XGEVA
These bone drugs are still large, but they are now the main headwind. Combined sales dropped 33% year over year in the second quarter of 2026.
Biosimilars
Amgen also sells biosimilars, which are lower-cost versions of complex biologic drugs. This business grew 29% year over year in the second quarter.
MariTide
MariTide is Amgen's late-stage obesity drug candidate. New Phase 3 studies will test less frequent dosing schedules like once a month or once a quarter.
One reported segment, many drug lines
Amgen reports as one human therapeutics segment. In the second quarter of 2026, 6 key growth drivers represented about 70% of total product sales.
What could break the thesis
Prolia and XGEVA erosion
High impact · High oddsThe denosumab franchise is shrinking fast after losing exclusivity. Prolia and XGEVA sales fell 33% year over year in the second quarter of 2026. Management expects continued erosion as multiple biosimilars launch globally.
Bigger IRS tax dispute
High impact · Medium oddsAmgen is waiting for a U.S. Tax Court decision on its 2010 to 2015 IRS dispute, expected no earlier than the second half of 2026. The risk expanded when the IRS also started auditing the 2016 to 2018 tax years with similar profit allocation claims.
MariTide disappoints
High impact · Medium oddsMariTide is the largest pipeline swing because obesity is a huge market and current leaders dose weekly. A less frequent schedule could help, but only if the drug shows strong weight loss, clean safety, and good patient persistence.
Oral competition for Repatha
Medium impact · Medium oddsMerck recently secured approval for an oral PCSK9 drug, creating new cardiovascular competition. Amgen believes Repatha remains more convenient because the oral option requires strict fasting restrictions, but primary care adoption remains a risk.
Drug pricing pressure
Medium impact · High oddsGovernment and commercial payers keep pushing for lower net prices. Otezla was selected for Medicare price setting beginning in 2027, which Amgen expects to cause further net selling price declines.
In one breath
What is Amgen known for?
Amgen is known for biologic medicines used in bone disease, cancer, heart disease, rare disease, inflammation, and other serious illnesses. Its major current growth products include Repatha, EVENITY, UPLIZNA, TEPEZZA, TEZSPIRE, oncology drugs, and biosimilars.
Why are Prolia and XGEVA a problem for Amgen?
Prolia and XGEVA lost key protection and now face biosimilar competition. Their combined second quarter 2026 sales fell 33% year over year to $1.1 billion, and management expects continued erosion.
What is MariTide?
MariTide is Amgen's late-stage obesity drug candidate. Amgen is running 12 Phase 3 studies to see if patients can take it monthly or quarterly instead of weekly.
What is the biggest legal risk for Amgen?
The biggest legal risk is the IRS tax dispute over profit allocation between the United States and Puerto Rico. The 2010 to 2015 case is waiting for a U.S. Tax Court decision, and the IRS is now also auditing the 2016 to 2018 tax years.
