Zarxio

Common Uses

Zarxio is primarily used to treat or prevent a condition called neutropenia, which is an abnormally low level of white blood cells (neutrophils). Because white blood cells are essential for fighting infections, having low levels can make a person more likely to get sick. This medication is used in the following situations:

• Chemotherapy Support: It is used for patients with certain types of cancer who are receiving chemotherapy that suppresses the immune system. It helps lower the risk of infection and fever caused by low white blood cell counts.
• Bone Marrow Transplants: For patients undergoing bone marrow transplants, Zarxio helps speed up the recovery of white blood cells after high-dose chemotherapy.
• Severe Chronic Neutropenia: It is used for long-term treatment of people born with low white blood cell counts or those who develop chronic low counts for unknown reasons (idiopathic or cyclic neutropenia).
• Stem Cell Collection: It is used to move blood-forming stem cells from the bone marrow into the bloodstream so they can be collected for use in a transplant.
• Acute Myeloid Leukemia (AML): It helps reduce the time it takes for white blood cell levels to return to normal after chemotherapy for AML.

Mechanism of Action

Zarxio is a man-made version of a natural protein produced in the body called granulocyte colony-stimulating factor (G-CSF). It belongs to a class of medications known as colony-stimulating factors.

Increasing White Blood Cells

The primary function of Zarxio is to act on the bone marrow to increase the production and release of neutrophils, a specific type of white blood cell. These cells are essential for the immune system to identify and destroy harmful bacteria and fungi.

Protecting the Immune System

Certain medical conditions or treatments, such as chemotherapy, can lower the number of white blood cells in the body. This condition, called neutropenia, increases the risk of developing serious or life-threatening infections. Zarxio helps manage this risk by:

• Encouraging the bone marrow to create new neutrophils more quickly.
• Helping the body maintain a sufficient level of white blood cells during treatment.
• Shortening the duration of time a patient spends with a dangerously low white blood cell count.

Common Side Effects

The most frequent side effect of Zarxio is pain in the bones, joints, or muscles. Other common side effects include:

• Redness, swelling, or itching where the injection was given
• Headache
• Fever
• Nausea or vomiting
• Tiredness
• Hair loss
• Rash
• Constipation or diarrhea

Serious Side Effects

While less common, Zarxio can cause serious medical issues. Contact a doctor immediately if you experience:

• Spleen injury: Pain in the left upper stomach area or the left shoulder.
• Lung problems: Shortness of breath, trouble breathing, or a fast rate of breathing.
• Severe allergic reactions: Shortness of breath, swelling of the face or throat, hives, or a fast heartbeat.
• Kidney damage: Dark-colored urine or swelling in the face and ankles.
• Capillary leak syndrome: Sudden swelling, puffiness, or a feeling of fullness in the body.
• Vasculitis: Purple spots or redness on the skin.
• Low platelet count: Increased bruising or bleeding.

Serious Complications

Splenic Rupture: Spleen rupture, which can be fatal, has been reported in patients receiving filgrastim products. Medical attention is necessary if there is pain in the left upper abdomen or the left shoulder tip.

Acute Respiratory Distress Syndrome (ARDS): This serious lung condition can occur. Symptoms include fever, shortness of breath, or rapid breathing. If ARDS occurs, the medication may be discontinued.

Serious Allergic Reactions: Severe allergic reactions, including anaphylaxis, can happen. These reactions may occur with the first dose or subsequent doses. Symptoms can include rash, swelling around the mouth or eyes, wheezing, and dizziness.

Other Major Precautions

Sickle Cell Disorders: Severe and sometimes fatal sickle cell crises can occur in patients with sickle cell disorders who receive filgrastim products.

Kidney Injury: Glomerulonephritis (inflammation of the kidney filters) has been reported. Symptoms include puffiness in the face or ankles, blood in the urine, or decreased urination.

Capillary Leak Syndrome: This condition causes fluid to leak from blood vessels into body tissues. Symptoms include swelling, puffiness, decreased urination, and a feeling of fullness or bloating.

Aortitis: Inflammation of the aorta (the large blood vessel leaving the heart) may occur. Symptoms include fever, abdominal pain, and feeling tired.

Myelodysplastic Syndrome and Leukemia: In patients with certain conditions like chronic neutropenia, there is a risk of developing myelodysplastic syndrome (MDS) or acute myeloid leukemia (AML).

Monitoring and Contraindications

• Blood Cell Counts: Regular blood tests are performed to monitor white blood cell counts, as excessively high levels (leukocytosis) can occur.
• Contraindications: Zarxio should not be used by individuals with a history of serious allergic reactions to filgrastim or pegfilgrastim products.

Pregnancy

There are no adequate and well-controlled studies regarding the use of Zarxio in pregnant women. Research in animals has shown that filgrastim products may cause adverse effects on the fetus when administered at very high doses, but these results do not always predict how the drug will affect human pregnancies. Because of the lack of human data, healthcare providers typically only prescribe Zarxio during pregnancy if the medical necessity justifies the potential risks.

Breastfeeding

It is not known whether Zarxio is excreted in human breast milk. Because many medications are passed through breast milk and could potentially affect a nursing infant, caution is recommended. Individuals who are breastfeeding or planning to breastfeed should consult with their healthcare provider to weigh the benefits of the medication against the potential risks to the infant.

Dosage Forms

Zarxio is supplied as a sterile, preservative-free solution for injection. It is available in the following form:

• Prefilled Syringe: A delivery system that includes a needle guard to help prevent injury after administration.

The medication is administered either as an injection under the skin or as an infusion into a vein.

FDA Approval History

Zarxio was approved by the U.S. Food and Drug Administration (FDA) in March 2015. It was the first biosimilar product to receive FDA approval in the United States. A biosimilar is a biological product that is highly similar to a reference product already approved by the FDA, which in this case is Neupogen (filgrastim).

Approved Indications

The FDA has approved Zarxio for several indications related to low white blood cell counts (neutropenia):

• Reducing the incidence of infection in patients with non-myeloid malignancies receiving myelosuppressive anti-cancer drugs.
• Reducing the duration of neutropenia in patients with acute myeloid leukemia receiving induction or consolidation chemotherapy.
• Reducing the duration of neutropenia and related clinical issues in patients undergoing bone marrow transplantation.
• Mobilizing autologous hematopoietic stem cells into the peripheral blood for collection.
• Reducing the incidence and duration of symptoms in patients with symptomatic severe chronic neutropenia.

Regulatory Oversight

Zarxio is a prescription-only medication. While it does not carry a Boxed Warning or require a Risk Evaluation and Mitigation Strategy (REMS) program, it is regulated to ensure it meets the same high standards of quality and efficacy as the reference biological product.

Insurance and Out-of-Pocket Costs

The price of Zarxio can vary significantly based on your health insurance plan. Most insurance providers, including Medicare and Medicaid, provide coverage for this medication, though you may still be responsible for copayments or coinsurance. Because Zarxio is a biosimilar, it is typically less expensive than the reference product, Neupogen.

Financial Support Programs

Financial assistance may be available for patients who meet certain eligibility requirements. These options often include:

• Manufacturer Patient Assistance: Programs designed to help patients with limited insurance coverage or high out-of-pocket costs.
• Co-pay Cards: Savings cards that can reduce the cost for patients with commercial insurance.

Patients should consult with their healthcare provider or pharmacist to determine the most accurate cost based on their specific treatment plan and insurance status. Because Zarxio is often administered in a clinical setting, costs may also include fees for the healthcare professional's time and the supplies used for the injection.