Neupogen vs. Neulasta: What to Know About These White Blood Cell-Boosting Medications

Chemotherapy (“chemo”) is the original cancer-fighting treatment. To this day, it’s a mainstay of cancer treatment because it works quickly to kill cells that divide and grow quickly. By killing rapidly-growing cancer cells, we can slow and shrink the growth of malignant tumors.

The problem with chemotherapy is that it isn’t very specific. In addition to killing cancer cells, chemotherapy can also kill other rapidly dividing healthy cells. This includes hair cells, cells that line your mouth and intestines, and blood cells. Chemotherapy that kills different blood cells is called myelosuppressive chemotherapy. 

Medications such as Neupogen and Neulasta help reduce the risk of complications from low levels of one type of blood cell — white blood cells.

What is neutropenia?

One important category of blood cells are white blood cells (WBCs). They’re important for a healthy immune system. There are different types of WBCs that your healthcare provider can monitor. The most common WBC is the neutrophil. These cells are important for fighting infection.

So, if chemotherapy kills WBCs — specifically neutrophils — then you’re at risk for neutropenia. This is when your neutrophil counts are too low. This can lead to complications like infection or sepsis.

Neutropenia is measured based on something called an absolute neutrophil count (ANC). A normal ANC is around 2,500 to 6,000 neutrophil cells per microliter (mcL). There are three different levels of neutropenia:

• Neutropenia: ANC is less than 1,500 cells/mcL

• Severe neutropenia: ANC is less than 500 cells/mcL

• Febrile neutropenia: ANC less than 1,500 cells/mcL and you have a fever 

Neutropenia typically happens around 7 to 12 days after chemotherapy, but this may vary depending on your type of chemotherapy. This is where Neupogen and Neulasta come in.

What is Neupogen?

Neupogen (filgrastim) is a colony-stimulating factor medication. This means that it helps make blood cells — in this case, neutrophils. It’s approved to help prevent infection from febrile neutropenia, reduce the amount of time for neutrophils to recover, and prevent severe complications from neutropenia in different types of cancer. Neupogen can also help prepare cells to be collected for a stem cell transplant.

Neupogen can be given as an intravenous (IV) infusion or an under-the-skin (subcutaneous) injection. It’s administered once daily for several days after chemotherapy.

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What is Neulasta?

Neulasta (pegfilgrastim) is another colony-stimulating factor medication. It’s also approved to decrease the risk of infection from febrile neutropenia. Neulasta can also be received by people who have been treated with high doses of radiation.

While Neulasta is also injected under the skin, it’s a longer-acting form that only needs to be injected once. This is because Neulasta is pegylated, so it lasts longer than Neupogen (think: Neu-last-a).

How do colony-stimulating factors work?

Blood cells, like WBCs and other types of immune cells, all grow from a common precursor: a stem cell. Stem cells can evolve into different types of cells depending on the kinds of prompts they get from your body. 

Neupogen and Neulasta are types of colony-stimulating factors (CSFs), or growth factors. They bind to surface proteins on stem cells to help them mature into infection-fighting neutrophils.

How are Neupogen and Neulasta dosed and given?

Neupogen is dosed in a few different ways. 

When receiving chemotherapy that lowers your blood counts, Neupogen can be started at a dose of 5 mcg per kg body weight. This is started at least 24 hours after chemotherapy ends and is injected daily. Neupogen is given for up to 2 weeks or until your ANC is around 10,000 cells/mcL.

Neupogen dosing can slightly vary for other situations. For instance, if you’re preparing for a bone marrow transplant with chemotherapy, you may receive 10 mcg of medication per kg body weight for a day as an infusion after chemotherapy. This is followed by under-the-skin injections.

Neulasta dosing for adults is more simple. It’s given as a one-time dose of 6 mg under the skin. After chemotherapy, it’s injected 24 hours after treatment. It shouldn’t be given 14 days before the next round of chemotherapy.

When Neulasta is given to children, the dose is based on body weight. Their healthcare provider will determine the correct dose.

How effective are Neupogen and Neulasta?

Many studies have looked at how effective Neupogen and Neulasta are for preventing febrile neutropenia.

One study looked at two groups of people being treated with a combination of myelosuppressive chemotherapies. One group was treated with Neupogen after chemotherapy, while the other wasn’t treated with anything (placebo). The authors found that 40% of people treated with Neupogen developed febrile neutropenia compared to 77% of people receiving placebo. The study also found that Neupogen lowered the occurrence and duration of infection and the occurrence of severe neutropenia.

In another study, people receiving myelosuppressive chemotherapy were treated with either one dose of Neulasta or multiple doses of Neupogen. The study found that the duration of severe neutropenia wasn’t any different between Neulasta and Neupogen. This established Neulasta as another option for preventing febrile neutropenia.

What are the known side effects of Neupogen and Neulasta?

When looking at data from clinical trials of Neupogen and Neulasta, it can be difficult to tease out which side effects were from the chemotherapy given and which were from the growth factor. Keeping this in mind, possible Neupogen side effects and Neulasta side effects include:

• Injection site reactions, like redness, swelling, or bruising where it was injected

• Bone pain

• Pain in the muscles, joints, back, or legs

• Headache

• Rash

• Diarrhea

• Weakness

• Nausea and vomiting

• Changes in appetite

Rare but serious side effects include:

• Fever

• Enlarged spleen

• Breathing problems

• Serious allergic reactions

• Sickle cell crisis in people with sickle cell anemia

• Kidney damage

• Capillary leak syndrome (leaky small blood vessels)

• Cancer risk

• Blood vessel damage

Always talk to your provider if you notice any side effects, especially if they develop after you go home from the hospital or clinic.

Are there biosimilars to Neupogen and Neulasta?

Yes. 

A biosimilar medication is “highly similar” to another FDA-approved biologic product (called a “reference” product). Like generic versions of brand-name medications, biosimilars usually cost less than their reference biologic. And they don’t have any meaningful differences in safety or effectiveness.

Biosimilars to Neupogen include:

• Nivestym (filgrastim-aafi)

• Releuko (filgrastim-ayow)

• Zarxio (filgrastim-sndz)

Biosimilars to Neulasta include:

• Fulphila (pegfilgrastim-jmdb)

• Fylnetra (pegfilgrastim-pbbk)

• Nyvepria (pegfilgrastim-apgf)

• Stimufend (pegfilgrastim-fpgk)

• Udenyca (pegfilgrastim-cbvq)

• Ziextenzo (pegfilgrastim-bmez)

Though not a biosimilar, Neulasta also has another product called Neulasta On-body Injector (OBI). This is a patch that contains an automatic injector. It’s filled with Neulasta and automatically injects into the skin about 27 hours after the patch is placed on your skin.

How to save on Neupogen and Neulasta

Neupogen and Neulasta are both available as reference medications. But you can also find them as lower-cost biosimilars. GoodRx can help you navigate ways to save on your prescription.

• Save with patient assistance programs. If you’re uninsured or underinsured, you may be eligible for the Neupogen or Neulasta patient assistance programs, which offer the medications at no charge.

• Save with a copay savings card. If you have commercial insurance and meet eligibility requirements, Neupogen’s price or Neulasta’s price is as little as $0 for your first fill if you use a manufacturer’s savings card.

• Save with a biosimilar. Depending on your location and situation, you may be eligible for a biosimilar version of Neupogen or Neulasta. Your healthcare provider can tell you more about this, if applicable.

How do healthcare providers decide which medication to prescribe?

Neupogen and Neulasta (and their biosimilars) are specialty medications. Their price tags can make them harder to access compared to non-speciality medications. 

When prescribed to be given at home, both Neupogen and Neulasta are often covered by your prescription drug insurance (or pharmacy benefit). This benefit will determine which product — either the reference product or a biosimilar — is covered. These will often require a prior authorization before the prescription can be processed. Your healthcare provider will typically choose the product that is covered or cheapest since they’re equally effective.

When a growth factor is required during an admission in the hospital, the short-acting form (filgrastim) is typically used. The type of filgrastim used — Neupogen or a biosimilar — will depend on what’s available at the hospital.

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Written by:

Emmeline C. Academia, PharmD, BCOP

Emmeline C. Academia, PharmD, BCOP, has been a practicing clinical pharmacist in adult oncology since 2020. She is a clinical pharmacy specialist in oncology at Beth Israel Deaconess Medical Center, in Boston.

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.

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