Filgrastim Biosimilars: What to Know About Zarxio and Other Neupogen Alternatives

We’ve come a long way with cancer medications. Chemotherapy was first discovered during World War II, and many more chemotherapies have been approved since then. But these medications can harm cancer cells and healthy cells, making them hard to tolerate. 

Researchers are constantly discovering, tweaking, and refining cancer medications. In addition to chemotherapy, healthcare providers now have access to treatments that can target specific cancer cells and decrease side effects. We can even modify our own immune system to fight off cancer.

Biosimilars are one of these newer developments. They’re biologic medications that are “highly similar” to an original FDA-approved biologic. Biologics are complex medications that come from living sources, such as bacteria, tissues, and proteins. Like generic versions of brand name medications, biosimilars are developed to make biologic treatments more affordable and widely available.

Promotional Disclosureinfo_outlined

SPECIAL OFFER

An interchangeable biosimilar to Humira® for 92% less

Introducing Adalimumab-adbm, an autoimmune medication that is the first-ever FDA-approved interchangeable biosimilar to Humira®. Get it for 92% less than the Humira® list price.

Save now

Filgrastim (Neupogen) is a biologic medication that currently has three biosimilars: Zarxio (filgrastim-sndz), Nivestym (filgrastim-aafi), and Releuko (filgrastim-ayow). They all can be given to people who are receiving cancer treatment. Below, we’ll discuss important facts about filgrastim biosimilars and whether there are any major differences between them. 

What is filgrastim?

Filgrastim (Neupogen) is a medication that’s used to increase neutrophils, a type of white blood cell that fights infection. It’s used for the following purposes:

• To prevent infection in people with low neutrophils caused by chemotherapy, radiation, or cancer

• To prevent infection in people with chronically low neutrophils caused by a non-cancer related or unknown cause

• To collect stem cells in people with blood cancers who are preparing for a stem cell transplant

Promotion disclosure

Neupogen (Nivestym)

Avg retail price

$354.76(Save 40.43%)

GoodRx discount

$211.32

See all discounts

How it works

Use GoodRx to find medications, pharmacies, and discounts.

GoodRx discounts can help you pay less for your prescription.

Bring your free coupon or savings card to the pharmacy.

Filgrastim is typically given as an under the skin (subcutaneous) injection once daily until your neutrophils increase to an acceptable level. But it can also be given as an infusion in your vein. The subcutaneous injection can either be given to you at your healthcare provider’s office or you can give it to yourself.

Filgrastim itself isn’t a cancer treatment. It’s considered a supportive care medication that helps relieve certain complications of your condition. It’s part of a group of medications called granulocyte colony-stimulating factors.

Neupogen vs. filgrastim biosimilars

As mentioned before, biosimilars are developed to make biologic medications more affordable and accessible. More biologics in the market creates competition among manufacturers. This makes biologic medications like filgrastim more affordable by driving prices down. 

However, biosimilars are not the same as generics. Generics are exact copies of a brand-name medication. And because they’re made chemically, these medications are easier to copy. Biosimilars are made from living sources, so it’s impossible to replicate them exactly. As a result, biosimilars may differ slightly from the original medication. But do these small differences matter?

No. Biosimilars still have to undergo comprehensive testing, similar to generics. Biosimilar manufacturers must also submit data to the FDA that proves they’re just as safe and effective as their original medications.

The main differences between Neupogen and its biosimilars are their FDA-approved uses and formulations.

1. Zarxio

Zarxio became the first FDA-approved filgrastim biosimilar in 2015. In fact, it was the first-ever biosimilar product approved in the U.S. 

Zarxio has all the same approved indications as Neupogen — with the exception of one. It’s not approved for people who have low neutrophils due to large doses of radiation. Radiation aside, its expected benefits and risks are highly similar to Neupogen.

In addition, Zarxio only comes as a prefilled syringe in doses of 300 mcg/0.5 mL and 480 mcg/0.8 mL. By comparison, Neupogen comes as both a prefilled syringe and a vial at doses of 300 mcg and 480 mcg. Prefilled syringes make it easier for people to give the injections to themselves. 

One downside to Zarxio’s prefilled syringe is that you can’t give doses of less than 0.3 mL (180 mcg) at a time. This is because there’s a special needle guard that interferes with the ability to see the lines that measure out lower doses.

Storage is also a consideration. Both Zarxio and Neupogen should be stored in the refrigerator until ready to use. It’s recommended to let them come to room temperature for 30 minutes before injecting so it stings less. After that, Zarxio prefilled syringes can be left at room temperature for up to 4 days. Neupogen prefilled syringes and vials can only be left out for up to 24 hours.

2. Nivestym

Nivestym became the second FDA-approved filgrastim biosimilar in 2018. Like Zarxio, Nivestym has all the same approved uses as Neupogen — with the exception of use in people with low neutrophils due to large doses of radiation. It has comparable risks and benefits, too.

Unlike Zarxio, Nivestym and Neupogen share the same formulations. They both come as vials and prefilled syringes in 300 mcg and 480 mcg dosages. Nivestym’s prefilled syringes also don’t allow for doses lower than 0.3 mL (180 mcg). But since the vials are available, these can be used for low doses when needed. 

Like Neupogen, Nivestym can only be left out at room temperature for up to 24 hours.

3. Releuko

Releuko became the third FDA-approved filgrastim biosimilar in 2022. It’s the most recent filgrastim biosimilar to be approved.

However, compared to the other biosimilars, Releuko has the fewest number of matching uses with Neupogen. It has two fewer approved uses. It’s not approved for people with low neutrophils due to high radiation doses or to help people prepare for a stem cell transplant.

Releuko has the same available dosage forms as Neupogen — vials and prefilled syringes in the 300 mcg and 480 mcg strengths. Vials should be used for any doses below 0.3 mL (180 mcg). Like Nivestym and Neupogen, Releuko can only be left out at room temperature for up to 24 hours.

What about Granix?

Granix (tbo-filgrastim) is another medication that’s comparable to Neupogen.

However, Granix is not technically a filgrastim biosimilar. It was approved before the FDA’s official biosimilar approval pathway was created. And it’s only approved for one of the six filgrastim indications — increasing low white blood cells in people receiving chemotherapy.

That being said, Granix is still similar to Neupogen in practice. Your healthcare provider may choose to give you one or the other depending on your situation.

How to choose the best filgrastim biosimilar

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

One exception is for people who have low neutrophils due to large doses of radiation. You’ll likely need to stick with Neupogen in this case. Biosimilars are not approved for this use. Another exception is if you’re taking it to prepare for a stem cell transplant. Releuko is not FDA approved for this indication, so you’ll want to stick with Neupogen, Zarxio, or Nivestym.

What’s more, if you or your child are prescribed a dose of 180 mcg or less, you probably won’t receive a prescription for Zarxio. The manufacturer doesn’t make vials, and prefilled syringes limit you from being able to measure doses this small. 

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, Neupogen, Zarxio, and Nivestym 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.

Why trust our experts?

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:

Sonja Jacobsen, PharmD, BCPS, BCOP

Sonja Jacobsen, PharmD, BCPS, BCOP,  is a clinical oncology pharmacy specialist currently practicing in Seattle. She has been practicing as a pharmacist since 2015 and is licensed to practice in Washington state and North Carolina.

Our editorial standards

Meet our experts