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Rheumatoid ArthritisSeptember 2023Summary reviewed June 2026

What Researchers Found Testing Switching Between Biosimilar and Original Humira

This study tested whether people with rheumatoid arthritis could safely switch back and forth multiple times between the original Humira and a biosimilar version called adalimumab-afzb. After three switches over 22 weeks, blood levels of the drug and side effects were the same in people who switched compared to those who stayed on original Humira the whole time.

What the trial was testing

The trial enrolled 455 patients with rheumatoid arthritis. The study was sponsored by Pfizer and tracked outcomes across the full group of patients who matched the trial's eligibility profile.

It was a large trial designed to confirm whether the treatment works well enough for wider use. Trials at this stage are designed to produce evidence regulators and physicians can act on — not just observations to follow up later.

What the results showed

Switching between biosimilar and original Humira three times showed no difference in drug levels or safety.

The Lancet. Rheumatology · 2023 · NCT04230213

These findings — that patients switched three times between versions with identical safety and drug levels — were published in the The Lancet. Rheumatology and represent the headline result of the study.

Researchers tracked outcomes across 455 patients enrolled in the trial. The result was consistent enough across the group that the team felt confident reporting it.

What this means for patients

For patients with rheumatoid arthritis, this result changes the calculus on what to ask their care team about. Whether it changes day-to-day care depends on factors like disease subtype, prior treatments, and where the patient is in their care journey.

What you can do now

This biosimilar is FDA-approved and available now. The study shows that switching between the biosimilar and original Humira multiple times is safe and works just as well. If your insurance or doctor suggests switching to save costs, this research supports that it's a reasonable option. Talk to your rheumatologist about whether a biosimilar makes sense for you.

Eligibility for the treatments mentioned above depends on specific test results and clinical history. Bring this summary, the trial name, and your most recent labs or pathology report to your next visit.