- Biosimilars match costly arthritis drugs in real-world use
- Helps people with ankylosing spondylitis save money
- Already in use across Europe, coming to U.S. clinics soon
This could cut treatment costs in half without losing results.
It started with a bill. John, 42, opened his insurance statement after his monthly infusion. The charge: $4,800. He’d been stable for years — no flare-ups, no hospital visits. But the cost never stopped rising. Then his doctor switched him to a new version of the same drug. Same effect. Half the price.
He wasn’t alone. Thousands like him are quietly switching to more affordable versions of powerful arthritis drugs — and staying just as healthy.
Why prices hurt
Ankylosing spondylitis (AS) is a type of arthritis that mainly attacks the spine. It causes pain, stiffness, and in some cases, bones in the spine can grow together. Movement becomes hard. Breathing deeply can hurt.
It affects about 1 in 200 adults. Most start having symptoms in their 20s. There’s no cure, but strong drugs can keep it under control.
For years, one class of drug has helped: TNF inhibitors. They calm the immune system’s overreaction. But they’re expensive — often over $5,000 a month.
And that cost hits patients directly. Even with insurance, co-pays add up. Some skip doses. Others go into debt.
Same medicine, lower price
We used to think only the original biologic drugs could do the job well. These are complex medicines made in labs using living cells. Because they’re so intricate, copying them exactly seemed impossible.
But here’s the twist: scientists can now make very close copies. These are called biosimilars.
They aren’t generics like those for blood pressure pills. But they’re similar enough — in structure, function, and effect — to be used the same way.
What’s different this time? Real proof they work after a switch.
Like a twin, not a clone
Think of the original drug as a custom-built car. Every part is handcrafted. Now imagine a team studies that car — every wire, every gear — and builds a near-identical version.
It’s not exactly the same factory. But it drives the same. Gets the same mileage. Handles the same roads.
That’s a biosimilar. It matches the original in purity, strength, and performance — down to the molecular level.
Regulators require strict testing before approval. Labs compare them side by side. Then small studies check if the body handles them the same.
Only after all that do they go to patients.
What the data says
Researchers looked at every major study from 2013 to 2025 — including clinical trials and real-world reports from nine countries.
They focused on patients with stable AS who switched from the original infliximab (a common TNF inhibitor) to a biosimilar version.
Over 3,500 patients were tracked. Some followed for more than two years.
No step back
The big finding? Patients stayed stable after the switch.
In one trial, 95% of people kept the same level of disease control six months later. Pain, stiffness, fatigue — all stayed low.
Another study followed patients for two years. Disease activity scores didn’t rise. Fewer than 1 in 10 stopped treatment — and most did so for reasons unrelated to effectiveness.
Side effects were nearly identical. Some reported new symptoms after switching. But many of those also occurred in the group that stayed on the original drug.
This doesn’t mean this treatment is available yet.
But there’s a catch.
Some patients felt worse — not because the drug failed, but because they expected it to.
This is called the nocebo effect. If someone believes a new drug won’t work, their body may react as if it’s true — even when it’s not.
In one registry, patients who weren’t told about the switch did better than those who were anxious about it.
Experts say trust and clear communication are key. Doctors who explain how biosimilars are tested see fewer dropouts.
“It’s not just about the molecule,” said one rheumatology advisor. “It’s about the message.”
If you’re on a TNF inhibitor and doing well, a switch to a biosimilar may be coming — and it’s likely safe.
Many insurers and hospitals are already making the change to cut costs. In Norway, over 80% of AS patients use biosimilars. The U.K. and Canada are following.
In the U.S., adoption is growing. Some clinics now start patients on biosimilars first. Others switch stable ones after discussion.
You don’t need to ask for it — but you should understand it. Talk to your doctor if you’re unsure.
Not perfect, but strong
Most studies were not double-blind. That means patients and doctors knew who switched — which can bias results.
Also, long-term data beyond three years is still limited. And most research focused on infliximab. Less is known about switching other TNF inhibitors.
Still, the overall picture is consistent: no major differences in outcomes.
What’s next
More biosimilars are coming. Some target other immune pathways. Others aim to be even easier to use — like weekly pens instead of infusions.
Regulators are streamlining approval. Doctors are building better tools to monitor patients after a switch.
Health systems are watching savings add up — without harming care.
For patients like John, that means more stability in more ways than one.
The road ahead is about trust, access, and smarter spending — not new miracles, but wider reach.