By 2028, one of the most profitable drugs in history - Keytruda - will lose its patent protection. That’s not just a business event. It’s a turning point for millions of cancer patients, healthcare systems, and insurers around the world. Keytruda, made by Merck, brought in over $25 billion in sales in 2024 alone. But soon, cheaper versions - called biosimilars - will hit the market. And they’re not just copies. They’re scientifically validated alternatives that work just as well, but cost 15% to 35% less. This isn’t science fiction. It’s happening right now, and the next five years will reshape how we treat cancer, autoimmune diseases, and chronic conditions.
What Exactly Are Biosimilars?
Biosimilars are not the same as generic pills. Generics are exact copies of small-molecule drugs like aspirin or metformin. Biosimilars are copies of complex biologic drugs - proteins made from living cells. Think of it like cloning a handmade silk dress versus copying a T-shirt. The original (called the reference product) is grown in living cell cultures, and even tiny changes in temperature, pH, or nutrient mix can alter the final product. That’s why biosimilars can’t be identical. But they don’t need to be. The FDA requires them to show no clinically meaningful difference in safety, purity, or effectiveness. That means if a patient switches from Keytruda to its biosimilar, their immune system won’t react differently. Their tumor response won’t drop. Their side effects won’t spike.The Patent Cliff: $200 Billion at Stake
Between 2025 and 2030, over $200 billion in annual global sales for top biologics will become open for competition. This is the biggest patent cliff in pharmaceutical history. The biggest names? Keytruda (2028), Eylea (2025), Enbrel (2023, already entering), Humira (2023), and Cosentyx (2029). These aren’t obscure drugs. They treat everything from rheumatoid arthritis to macular degeneration to melanoma. And they’re expensive. A single year of Keytruda treatment can cost $150,000. With biosimilars, that could drop to $100,000 or less.Companies like Sandoz, Samsung Bioepis, Biocon Biologics, and Celltrion are racing to be first. Sandoz launched its Enbrel biosimilar in 2023 at a 35% discount. It now holds 40% of the U.S. market for that drug. Eylea, used to treat vision loss, saw three biosimilars approved in 2024 - Yesafili, Opuviz, and Enzeevu. By Q1 2025, they already made up 12% of prescriptions. That’s fast. And it’s just the start.
Why Is Keytruda the Big One?
Keytruda isn’t just another drug. It’s the backbone of modern cancer care. Used for lung, melanoma, head and neck, and several other cancers, it’s prescribed to over a million patients worldwide. Merck has built a fortress around it - 237 patents, some stretching to 2035. But the core patent expires in 2028. Fourteen companies are already in Phase 3 trials for their versions. Coherus BioSciences and Merck’s own authorized generic partner are the frontrunners. When they launch, expect prices to drop fast. The RAND Corporation estimates biosimilars could save the U.S. healthcare system $250 billion over the next decade. That’s not a guess. It’s based on what happened with Humira.Humira: The Blueprint for Success
Humira, the best-selling drug of all time, lost its patent in 2023. Twelve biosimilars were approved within a year. By 2024, 80% of new prescriptions were for biosimilars. Why? Because payers pushed hard. Medicare, Medicaid, and private insurers changed their rules to favor cheaper options. Hospitals updated their formularies. Pharmacists started substituting automatically. Patients didn’t notice a difference. And they saved thousands per year. The lesson? When you remove financial barriers, biosimilars win. And Keytruda will follow the same path.
The Catch: It’s Not Just About Price
There’s a big problem slowing things down. In the U.S., Medicare Part B pays providers based on the drug’s average sales price. That means if a doctor gives a patient a $150,000 drug, they get reimbursed more than if they give a $100,000 biosimilar. So some providers still prefer the original - even if the biosimilar is just as safe. It’s a financial incentive to keep prices high. That’s why it took 18 months after Humira biosimilars were approved for them to become the norm. The same delay is expected with Keytruda. But payers are catching on. Cigna now offers $0 copays for biosimilars. Centene mandates them for all new patients on TNF inhibitors. That’s changing the game.Manufacturing Is a Billion-Dollar Gamble
Making a biosimilar isn’t like making a pill. It’s like building a living factory. Samsung Bioepis spent $450 million on a single facility in South Korea just to produce biosimilars. Why? Because every batch must be identical. Even a 1% change in glycosylation - a sugar molecule attached to the protein - can affect how the drug works. For Keytruda, that means matching Merck’s exact molecular structure. Developers use advanced tools like mass spectrometry and cryo-electron microscopy to prove similarity. The FDA requires 12-18 months of review. And the cost? $150 million to $250 million per product. That’s why only big players can compete. Smaller companies can’t afford the risk.Europe Is Ahead. The U.S. Is Catching Up.
Europe approved its first biosimilar in 2006. Today, over 82 are on the market. In countries like Germany and Sweden, biosimilar use for drugs like Humira and Enbrel exceeds 70%. Why? Because governments set prices and demand savings. The U.S. lags at 30-40% adoption. But the gap is closing. The FDA approved 17 biosimilars in 2024 - up from just 5 in 2020. The agency also updated its Purple Book database to list patents in real time. That’s a big deal. It stops companies from using legal tricks to delay competition. In 2020, a patent settlement delayed Eliquis generics by four years. That won’t happen as easily anymore.
Real Patients, Real Stories
At the American Society of Clinical Oncology in 2024, Dr. Laura Chow shared data from 500 patients with inflammatory bowel disease who switched from Humira to its biosimilar. No increase in flare-ups. No new side effects. Just lower bills. But it’s not always smooth. Dr. Richard Pazdur from the FDA’s Oncology Center reported rare immune reactions when patients switched between different rituximab biosimilars. That’s why doctors don’t switch patients randomly. They monitor. They test. They communicate. And patients? A November 2024 survey by the Cancer Support Community found 78% were happy with the cost savings. But 34% didn’t understand how substitution worked. Education is still missing.What’s Next? The Next Wave
After Keytruda and Eylea, the next big targets are Cosentyx (2029), Stelara (2030), and Ozempic’s biologic cousin - semaglutide. But here’s the twist: drugmakers are fighting back. They’re making “next-generation” versions - slightly tweaked biologics that are harder to copy. These are called “biobetters.” They’re not biosimilars. They’re new drugs. And they’re designed to stay protected longer. But even then, biosimilars will still capture the bulk of the market. Goldman Sachs predicts they’ll take 75% of the revenue from expiring biologics by 2035. BMO Capital Markets thinks it’ll be closer to 55%. Either way, the savings are real.What This Means for You
If you’re a patient: Ask your doctor if a biosimilar is right for you. You’ll get the same treatment for less. If you’re a provider: Update your EHR system. Train your staff. Know which biosimilars are approved and interchangeable. If you’re a payer: Push for mandatory substitution. Negotiate value-based contracts. If you’re an investor: Look at companies building biosimilars - not just the big names, but the ones making the technology. Sandoz, Samsung Bioepis, and Alvotech are leading the charge.The future of biosimilars isn’t about whether they work. It’s about whether we let them in. The science is there. The savings are clear. The patients are ready. The only thing left is the system - and it’s starting to change.
Are biosimilars as safe as the original biologic drugs?
Yes. The FDA requires biosimilars to undergo extensive testing - including analytical studies, animal tests, and clinical trials - to prove they have no clinically meaningful differences in safety, purity, or effectiveness compared to the original. Thousands of patients have switched from drugs like Humira and Enbrel to their biosimilars with no increase in side effects or loss of effectiveness. For oncology drugs like Keytruda, the bar is even higher due to the critical nature of treatment.
Why are biosimilars cheaper than the original biologics?
Biosimilars cost less because their manufacturers don’t have to repeat the expensive, decade-long clinical trials the original drug required. Instead, they rely on data from the reference product and focus on proving similarity through advanced lab testing and targeted clinical studies. This cuts development costs from $2-3 billion to $150-250 million. They also face more competition, which drives prices down further.
Can I switch from my current biologic to a biosimilar?
Yes - but only if your doctor agrees and your insurance allows it. For some drugs, like Humira, the FDA has approved “interchangeable” biosimilars, meaning pharmacists can substitute them without asking your doctor. For others, like Keytruda, substitution may require a new prescription. Always talk to your healthcare provider before switching. Most patients who switch report no difference in how they feel.
Will biosimilars be available in my country?
Biosimilars are approved and used in over 70 countries. The U.S. and EU lead in approvals, but many low- and middle-income countries now have access through generic manufacturers. In South Africa, biosimilars for HIV and hepatitis are already in use. For cancer drugs like Keytruda, availability depends on local regulatory approval and pricing agreements. Most major biosimilar developers are expanding into emerging markets as patents expire globally.
What’s the difference between a biosimilar and a generic drug?
Generics are exact chemical copies of small-molecule drugs (like ibuprofen or metformin). Biosimilars are highly similar - but not identical - to complex biologic drugs made from living cells. Biologics are much larger and more sensitive to production changes. That’s why biosimilars require more testing than generics. You can’t just mix chemicals to make one. You need living cells, controlled environments, and advanced analytics.
How long does it take for a biosimilar to reach the market after patent expiry?
It can take 6-24 months after patent expiry for a biosimilar to become widely available. Even after FDA approval, manufacturers need time to scale production, negotiate with insurers, and update hospital systems. For Humira, it took 18 months after patent expiry for biosimilars to capture 80% of new prescriptions. For Keytruda, expect a similar lag - even though multiple biosimilars will be ready on day one.
Are there any risks in switching to a biosimilar?
The risk is very low, but not zero. Some patients, especially those on cancer or autoimmune treatments, may experience rare immune responses when switching between different biosimilar versions. That’s why doctors monitor patients closely after a switch. But large studies show no significant increase in adverse events. The FDA and EMA require post-market surveillance for all biosimilars. If any safety issue arises, it’s tracked and addressed quickly.
Biosimilars are a game-changer for patients who can't afford $150K a year just to stay alive. I've seen families choose between rent and treatment - this isn't just about profit margins, it's about dignity. The science is solid, the outcomes are proven, and the cost savings are real. We need to stop treating healthcare like a stock market and start treating it like a human right.
Doctors, insurers, and regulators all have a role to play. Let's not let bureaucracy delay what's already been proven safe. Patients aren't test subjects - they're people.