Monoclonal Antibody Biosimilars: Examples and Clinical Uses

When you hear the word biosimilar, you might think it’s just a cheaper version of a brand-name drug-like a generic pill. But monoclonal antibody biosimilars aren’t like that at all. They’re not copies. They’re not duplicates. They’re incredibly complex biological products that match the original drug so closely, doctors can use them with the same confidence. And they’re 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. It’s made of a single, simple chemical structure. Any lab can recreate it exactly. That’s why generics cost so little-they’re chemically identical to the original.

Monoclonal antibodies? They’re not chemicals. They’re 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 don’t 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. That’s why even the original drug isn’t perfectly uniform from batch to batch.

A biosimilar doesn’t need to be identical. It just needs to be highly similar-with no clinically meaningful differences in safety, purity, or potency. That’s 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 isn’t to prove it’s better. It’s to prove it’s 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 you’ll 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-Hodgkin’s 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 Crohn’s 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 aren’t niche drugs. They’re frontline treatments. A patient with metastatic breast cancer might get trastuzumab. Someone with severe rheumatoid arthritis might get adalimumab. And now, thanks to biosimilars, they’re 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. That’s not a small win. It’s life-changing for patients who can’t 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. That’s 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 “biosimilar.” Others are “interchangeable.”

An interchangeable biosimilar has passed an extra hurdle: it must show that switching back and forth between the reference product and the biosimilar doesn’t 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 wasn’t 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 EMA’s 2021 safety report found just 12 unexpected immune reactions. That’s 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 don’t get worse outcomes. In fact, many do just as well-or better-because they’re finally able to stay on treatment without financial stress.

The Future: What’s 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 isn’t 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 “very confident” prescribing biosimilars. Many still think they’re inferior. That’s changing, but slowly.
• Formulary restrictions: Pharmacy benefit managers (PBMs) often block biosimilars unless they’re the cheapest option. Sometimes, they favor the original drug because of rebates. That’s not about safety-it’s 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 aren’t a future idea. They’re here. They’re used every day in hospitals across the U.S., Europe, and beyond. They’re saving lives by making life-saving treatments affordable. They’re not generics. They’re 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.