Monoclonal Antibody Biosimilars: Examples and Clinical Uses
Dec, 11 2025
When you hear the word biosimilar, you might think itâs just a cheaper version of a brand-name drug-like a generic pill. But monoclonal antibody biosimilars arenât like that at all. Theyâre not copies. Theyâre not duplicates. Theyâre incredibly complex biological products that match the original drug so closely, doctors can use them with the same confidence. And theyâre changing how cancer and autoimmune diseases are treated-saving billions without sacrificing safety.
What Makes a Monoclonal Antibody Biosimilar Different From a Generic?
Think of a small-molecule generic drug like aspirin. Itâs made of a single, simple chemical structure. Any lab can recreate it exactly. Thatâs why generics cost so little-theyâre chemically identical to the original.
Monoclonal antibodies? Theyâre not chemicals. Theyâre proteins. Big ones. About 150,000 daltons in size. Made by living cells-usually in bioreactors filled with engineered Chinese hamster ovary cells. These cells donât just spit out one perfect protein. They make thousands of tiny variations: slight differences in sugar attachments (glycosylation), folding patterns, or even minor amino acid changes. Thatâs why even the original drug isnât perfectly uniform from batch to batch.
A biosimilar doesnât need to be identical. It just needs to be highly similar-with no clinically meaningful differences in safety, purity, or potency. Thatâs the standard set by the FDA and EMA. To prove it, manufacturers run over 100 analytical tests: mass spectrometry, chromatography, cell-based assays. They test in animals. Then they run clinical trials comparing the biosimilar directly to the reference product in hundreds of patients. The goal isnât to prove itâs better. Itâs to prove itâs just as safe and effective.
Approved Monoclonal Antibody Biosimilars and What They Treat
Since the first monoclonal antibody biosimilar was approved in Europe in 2013, the list has grown fast. In the U.S. alone, there are now more than 20 approved monoclonal antibody biosimilars. Here are the big ones youâll see in clinics:
- Bevacizumab biosimilars (for Avastin): Used to treat colorectal, lung, ovarian, and brain cancers. Six versions are approved in the U.S., including Mvasi, Zirabev, and Vegzelma.
- Rituximab biosimilars (for Rituxan): Used for non-Hodgkinâs lymphoma, chronic lymphocytic leukemia, and rheumatoid arthritis. Truxima, Ruxience, and Riabni are the three approved in the U.S.
- Trastuzumab biosimilars (for Herceptin): For HER2-positive breast and stomach cancers. Six options are available, including Ogivri, Herzuma, and Kanjinti.
- Infliximab biosimilars (for Remicade): For Crohnâs disease, ulcerative colitis, and rheumatoid arthritis. Remsima was the first to get FDA approval as interchangeable in July 2023.
- Adalimumab biosimilars (for Humira): The most prescribed biologic in the world. Since 2023, multiple biosimilars like Hyrimoz and Hadlima have entered the market.
These arenât niche drugs. Theyâre frontline treatments. A patient with metastatic breast cancer might get trastuzumab. Someone with severe rheumatoid arthritis might get adalimumab. And now, thanks to biosimilars, theyâre getting the same care at a fraction of the cost.
How Much Do Biosimilars Save?
Cost is the biggest driver behind their adoption. The original monoclonal antibodies can cost $10,000 to $20,000 per treatment cycle. Biosimilars launch at 15% to 35% lower prices-and often drop further over time.
A 2022 study in JAMA Oncology tracked 1,247 patients switching from reference rituximab to Truxima. The result? A 28% drop in cost per cycle-with no increase in side effects or drop in response rates. Thatâs not a small win. Itâs life-changing for patients who canât afford treatment, and for hospitals drowning in drug budgets.
Analysts at Evaluate Pharma predict biosimilar monoclonal antibodies will save the U.S. healthcare system $250 billion between 2023 and 2028. Bevacizumab, trastuzumab, and rituximab biosimilars will make up 78% of those savings. Thatâs because these three drugs are used in millions of cancer treatments every year.
Interchangeability: The Next Big Step
Not all biosimilars are created equal in the eyes of pharmacists. Some are just âbiosimilar.â Others are âinterchangeable.â
An interchangeable biosimilar has passed an extra hurdle: it must show that switching back and forth between the reference product and the biosimilar doesnât increase risk or reduce effectiveness. That means a pharmacist can substitute it without asking the doctor-just like they do with generic pills.
Remsima (infliximab) became the first monoclonal antibody biosimilar to earn this status in July 2023. More are expected. This is huge. It removes a major barrier: provider hesitation. When a pharmacist can swap automatically, access improves. Costs drop further. And patients get the same medicine, no matter which version is on the shelf.
Are Biosimilars Safe? What About Immune Reactions?
One of the biggest fears is immunogenicity-will the body reject the biosimilar? After all, even tiny changes in protein structure can trigger an immune response.
There have been rare cases. One infamous example involved cetuximab, where some patients had severe allergic reactions due to a sugar molecule called alpha-1,3-galactose. That wasnât a biosimilar issue-it happened with the original drug too. But it showed how sensitive these molecules are.
Since 2013, over 1.2 million patient-years of exposure to monoclonal antibody biosimilars have been tracked. The EMAâs 2021 safety report found just 12 unexpected immune reactions. Thatâs a rate of 0.001%-statistically the same as the reference products.
Real-world data from cancer centers in the U.S. and Europe show no increase in infusion reactions, antibody development, or loss of effectiveness over time. Patients who switch from the original to the biosimilar donât get worse outcomes. In fact, many do just as well-or better-because theyâre finally able to stay on treatment without financial stress.
The Future: Whatâs Coming Next?
The pipeline is packed. As of September 2023, the FDA had 37 monoclonal antibody biosimilars in review. The biggest targets? Pembrolizumab (Keytruda) and nivolumab (Opdivo)-the checkpoint inhibitors that revolutionized melanoma and lung cancer treatment. Six pembrolizumab biosimilars are in late-stage trials. If approved, they could cut the cost of these drugs by more than 50%.
Even more advanced products are on the horizon: bispecific antibodies (that target two cancer markers at once) and antibody-drug conjugates (that deliver chemo directly to tumor cells). The EMA plans to release new guidelines for these complex biosimilars by mid-2024.
By 2027, IQVIA predicts monoclonal antibody biosimilars will make up 35% of all biologic prescriptions in the U.S.-up from 18% in 2022. Cancer therapies will drive most of that growth, making up 62% of the volume.
Barriers Still Exist
Despite the progress, adoption isnât automatic. Three big hurdles remain:
- Patent litigation: Drugmakers fight biosimilar entry with lawsuits. On average, each monoclonal antibody biosimilar faces 14.7 patent challenges before approval, delaying market entry by years.
- Provider education: A 2022 ASCO survey found only 58% of oncologists felt âvery confidentâ prescribing biosimilars. Many still think theyâre inferior. Thatâs changing, but slowly.
- Formulary restrictions: Pharmacy benefit managers (PBMs) often block biosimilars unless theyâre the cheapest option. Sometimes, they favor the original drug because of rebates. Thatâs not about safety-itâs about profit.
But real-world results are convincing. When patients get access, they use it. When doctors see the data, they trust it. And when hospitals see the savings, they push for change.
Final Thoughts
Monoclonal antibody biosimilars arenât a future idea. Theyâre here. Theyâre used every day in hospitals across the U.S., Europe, and beyond. Theyâre saving lives by making life-saving treatments affordable. Theyâre not generics. Theyâre something better: scientifically rigorous, clinically proven, and economically essential.
If you or someone you know is on a biologic for cancer, rheumatoid arthritis, or another chronic condition, ask: Is there a biosimilar option? The answer might not just save money. It might make treatment possible.
Are monoclonal antibody biosimilars as safe as the original drugs?
Yes. Regulatory agencies like the FDA and EMA require biosimilars to show no clinically meaningful differences in safety, purity, or potency compared to the reference product. Real-world data from over 1.2 million patient-years of use shows immune reactions and side effects occur at the same low rates as with the original drugs. Clinical trials and post-market monitoring confirm equivalent safety profiles.
Can biosimilars be substituted for the original drug without a doctorâs approval?
Only if the biosimilar is designated as "interchangeable" by the FDA. As of 2025, Remsima (infliximab) is the first monoclonal antibody biosimilar with this status. Pharmacists can switch it for the original without consulting the prescriber-just like with generic pills. Other biosimilars require a new prescription for substitution.
Which cancers are treated with monoclonal antibody biosimilars?
Biosimilars of bevacizumab treat colorectal, lung, ovarian, and brain cancers. Trastuzumab biosimilars are used for HER2-positive breast and gastric cancers. Rituximab biosimilars treat non-Hodgkinâs lymphoma and chronic lymphocytic leukemia. These are some of the most common cancer types treated with biologics-and biosimilars are now standard options in treatment guidelines.
How do biosimilars compare in cost to the original biologics?
Biosimilars typically launch at 15% to 35% lower prices than the reference product. In real-world use, switching to biosimilars like Truxima has cut treatment costs by 28% per cycle. Over time, prices often drop further due to competition. Analysts project biosimilar monoclonal antibodies will save the U.S. healthcare system $250 billion between 2023 and 2028.
Why are there so many biosimilars for some drugs but not others?
Drugs with high sales volume and expiring patents attract more biosimilar developers. Bevacizumab, trastuzumab, and rituximab are among the top-selling biologics globally, with annual sales in the billions. That makes them prime targets. Newer drugs like Keytruda are still under patent protection, but multiple biosimilars are in late-stage development and will likely enter the market soon.
Lawrence Armstrong
December 12, 2025 AT 21:10These biosimilars are a game-changer. I work in oncology pharmacy, and seeing patients finally get access to trastuzumab without going bankrupt? Priceless. The data is solid - no drop in efficacy, no spike in reactions. Just cheaper, same-quality care. đ
Donna Anderson
December 14, 2025 AT 05:07omg yes!! my aunt just switched to the biosimilar for her rheumatoid arthritis and her bills dropped by half đ sheâs been able to keep going to PT and even started gardening again. biosimilars = literal lifesavers. đżđ
Adam Everitt
December 16, 2025 AT 01:20One might argue that the entire regulatory framework surrounding biosimilars is a construct of pharmaceutical capital, designed to appease the public while preserving profit margins under a new label. The âno clinically meaningful differenceâ standard - is that not a euphemism for âclose enoughâ? We measure proteins with machines, but can we ever truly capture the soul of a biological molecule? đ¤
wendy b
December 16, 2025 AT 15:05Actually, the FDAâs definition of âhighly similarâ is misinterpreted by laypeople. Itâs not âclose enoughâ - itâs statistically equivalent within pre-specified margins, validated through over 100 analytical assays, including glycosylation profiling and tertiary structure confirmation. Youâre conflating âidenticalâ with âequivalent.â Big difference. And yes, Iâve read the guidance documents. All of them.
Rob Purvis
December 18, 2025 AT 14:19Hey, just wanted to add - Iâve seen firsthand how biosimilars reduce delays in treatment. At my hospital, we used to wait 3-4 weeks for prior auth on Humira. Now, with Hadlima, itâs same-day. And patients? Theyâre way more likely to stick with treatment when theyâre not terrified of the bill. Also - big shoutout to the pharmacists who educate docs. Youâre the real MVPs.
Laura Weemering
December 19, 2025 AT 08:03But⌠what if the âequivalentâ efficacy is just a statistical mirage? What if the immune response is delayed? What if the glycosylation differences manifest as chronic inflammation five years later? Weâre treating millions with these drugs - and weâre supposed to trust a 12-month trial? The long-term data is still thin. And the fact that PBMs still push originators? Thatâs not science. Thatâs corruption.
Audrey Crothers
December 20, 2025 AT 03:29Yâall are overthinking this. Biosimilars = cheaper, same medicine. My cousin got her cancer treatment with a biosimilar and is now hiking every weekend. No drama. No side effects. Just⌠better access. đ Letâs stop the fear-mongering and just let people get better.
Stacy Foster
December 20, 2025 AT 13:32Theyâre not biosimilars. Theyâre knockoffs. The FDA is in bed with Big Pharma. Look at the patent lawsuits - 14.7 per drug? Thatâs not innovation. Thatâs a money grab. And the âinterchangeableâ label? A trick to make you think itâs safe. I know someone who got a rash after switching - they buried it in the data. They always do.
Reshma Sinha
December 21, 2025 AT 08:05As someone working in biologics manufacturing in India, I can confirm: the production complexity is insane. One tiny shift in pH or dissolved oxygen in the bioreactor can alter glycosylation. Thatâs why biosimilars take 5â7 years to develop. Itâs not just copying - itâs reverse-engineering a living system. The science here is heroic. We should be celebrating this, not doubting it.