Is There a Biosimilar to Rituximab? Yes, Here Are 3 Rituximab Biosimilars You Should Know

Picture this — you walk into the infusion clinic to start a medication called rituximab (Rituxan). You’re approved by insurance and educated on medication side effects and expectations; you’re good to go. As the nurse hangs the bag, you hear them say a different medication name. “Are you sure you haven’t made a mistake?” you ask. It’s not a mistake, the nurse explains. That’s because you are receiving a rituximab biosimilar.

But what is a biosimilar? Biosimilars are biologic medications that are “highly similar” to an original FDA-approved medication. Biologics themselves are complex medications that come from living sources. And while they aren’t exactly the same, biosimilars are meant to be just as effective and safe as the original biologic. 

Rituxan has three biosimilars: rituximab-abbs (Truxima), rituximab-pvvr (Ruxience), and rituximab-arrx (Riabni). We’ll discuss why rituximab biosimilars exist and whether there are any major differences between them.

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What is rituximab?

Rituximab (Rituxan) is a monoclonal antibody medication. It attaches to and marks certain white blood cells (B cells) for destruction. B cells are involved in development of certain blood cancers and autoimmune conditions.

Rituximab is administered into your vein. How often it’s given depends on what it’s being used for — this typically ranges from weekly to monthly. It’s approved to treat several health conditions in both kids and adults.

Rituximab vs. rituximab biosimilars

Why do biosimilars exist? The main reason is cost and medication accessibility. Adding biosimilars creates competition among manufacturers, which ultimately drives prices down. This helps make biologic medications like rituximab more affordable. 

Many people think that biosimilars are the same as generics. This is not technically true. Generics are exact copies of the original brand-name medication. Generics are also made chemically, so it’s easier to copy them and produce them in bulk. Biosimilars are made from natural and living sources, so it’s impossible to copy them exactly. This means that biosimilars may have slight differences from the original medication. But do these differences mean anything?

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Not really. Biosimilars still have to undergo rigorous quality testing, just like generics. Biosimilar manufacturers must also provide information to the FDA that proves their medication is just as effective and safe as the original product.

The main difference between Rituxan and its biosimilars is their FDA-approved indications. All approved uses are the same, except the biosimilars aren’t approved for pemphigus vulgaris. The biosimilars aren’t approved for use in children, either.

Now, let’s discuss each biosimilar more specifically.

1. Truxima

Rituximab-abbs (Truxima) became the first FDA-approved rituximab biosimilar in 2018. At first, it was only approved for NHL. But by mid-2020, its indications expanded to CLL, RA, and Wegener’s granulomatosis/microscopic polyangiitis. 

Various studies support these approved uses. For instance, Truxima’s approval for NHL and CLL was based on two studies comparing Truxima to Rituxan in people with a slow growing type of NHL.

The first study included people with advanced cancer being treated with both rituximab and chemotherapy. After 6 months, the cancer either shrank or disappeared in 97% of people receiving Truxima and 93% receiving Rituxan. Truxima was considered non-inferior to Rituxan, meaning it wasn’t any worse.

The second study was conducted in people with less advanced cancer being treated with rituximab alone. After 7 months, the cancer either shrank or disappeared in 83% of people receiving Truxima and 81% of people receiving Rituxan. Truxima was considered equivalent to Rituxan. 

2. Ruxience

Rituximab-pvvr (Ruxience) became the second FDA-approved rituximab biosimilar in 2019. Its first four uses were approved in 2019, but it became approved for RA in 2021.

Data also supports Ruxience’s approval for these health conditions. For NHL and CLL, one study compared Ruxience to MabThera (the European brand of rituximab) in people with less advanced NHL. After about 6 months, the cancer either shrank or disappeared in 76% of people receiving Ruxience compared to 71% with MabThera. Ruxience was considered equivalent to MabThera, which itself is similar to Rituxan.

3. Riabni

Rituximab-arrx (Riabni) became the third FDA-approved rituximab biosimilar in 2020. It has the same approved uses as Truxima and Ruxience; its approval for RA just came through in 2022. 

Riabni is also backed by supporting data. For example, one study compared Riabni to Rituxan in people living with NHL. After 7 months, the cancer either shrank or disappeared in 78% of people receiving Riabni and 70% of people receiving Rituxan. Riabni was considered equivalent to Rituxan.

For all three biosimilars, there were no major differences in side effects or safety concerns in the studies mentioned above.

How to choose the best rituximab biosimilar

Rituximab biosimilars are dosed and given the exact same way as Rituxan. And since there are no major differences in side effects or how well they work, the best choice generally comes down to affordability. The product you’ll receive often depends on your insurance status and what’s available to your healthcare provider.

The two exceptions are with pemphigus vulgaris and children. If you have pemphigus vulgaris or have a child being treated with rituximab, you’ll likely need to stick with Rituxan. Biosimilars are not approved for these scenarios.

Otherwise, if you do have the option to choose, check with your insurance company (if applicable) to see what their preferred product is. This can help limit what you pay out of pocket. If you have a high copay, all rituximab products have copay card options to help you access them at a lower cost.

Other options include finding funding from a charitable foundation, such as the Patient Access Network Foundation. You can also apply for the manufacturer’s patient assistance program to see if you qualify for free medication.

Switching between rituximab products

One area that’s less clear is whether it’s OK to switch from Rituxan to one of its biosimilars (or vice versa). 

Some people worry about how safe it is to switch between rituximab products. After all, rituximab biosimilars are not officially designated as being interchangeable with Rituxan. This means that manufacturers have not taken additional steps to prove that you can switch back and forth between products without issue.

However, in reality, your healthcare provider may still decide to switch between products. This will be based on their experience, what they have available at their institution, and available safety data.

For instance, studies in NHL and RA suggest that it’s safe to switch from Rituxan to Truxima. Researchers have also tested to see if it’s more likely for your body to react poorly to Truxima, Ruxience, or Riabni compared to Rituxan. These studies haven’t found any notable differences in the likelihood of experiencing a bad reaction.

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Written by:

Rachel Feaster, PharmD, BCOP, BCPS

Rachel Feaster has over 10 years of professional experience in ambulatory, inpatient, pharmacogenomics, and oncology care. She is board certified in oncology and pharmacotherapy.

Edited by:

Joshua Murdock, PharmD, BCBBS

Joshua Murdock, PharmD, BCBBS, is a licensed pharmacist in Arizona, Colorado, and Rhode Island. He has worked in the pharmacy industry for more than 10 years and currently serves as a pharmacy editor for GoodRx.

Reviewed by:

Alyssa Billingsley, PharmD

Alyssa Billingsley, PharmD, is the director of pharmacy content for GoodRx. She has over a decade of experience as a pharmacist and has worked in clinical, academic, and administrative roles.

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