Zolgensma is a brand-name prescription drug. It’s FDA-approved to treat spinal muscular atrophy (SMA) caused by genetic changes in the SMN1 gene. For this purpose, Zolgensma is given to children less than 2 years old.

SMA is a rare condition that damages nerve cells in the brain and spinal cord. This leads to muscle weakness and trouble with activities such as breathing, speaking, swallowing, and walking. For more information about this condition, see the “Zolgensma for spinal muscular atrophy” section below.

Drug details

Zolgensma contains the active ingredient onasemnogene abeparvovec. This drug is a type of gene therapy. It works by replacing an abnormal SMN1 gene with a normal SMN1 gene. For more information, see the “How Zolgensma works” section below.

Zolgensma comes as a liquid suspension. It’s given as a one-time intravenous infusion (an injection into a vein over a period of time) by a healthcare provider. The drug comes in one strength: 2 x 1013 vector genomes per milliliter (mL).* This is the number of viral particles that are in each mL of the drug.

FDA approval

In 2019, the Food and Drug Administration (FDA) approved Zolgensma to treat SMA in children less than 2 years old. Zolgensma is the first gene therapy to receive FDA approval for the treatment of SMA.

Effectiveness

Zolgensma is given as a one-time dose. Clinical studies haven’t looked at how effective the drug may be if a child receives more than one dose.

Zolgensma also hasn’t been studied as a treatment for advanced SMA. “Advanced” means the disease has worsened. This may lead to conditions such as paralysis of the arms and legs or needing to use a ventilator to breathe.

For more information about the effectiveness of Zolgensma, see the “Zolgensma for spinal muscular atrophy” section below.

Zolgensma is only available as a brand-name medication. Zolgensma contains the active ingredient onasemnogene abeparvovec-xioi.* It’s a biologic drug that isn’t currently available in biosimilar form.

Biologic drugs are made from living cells, so they can’t be copied exactly. Non-biologic drugs are made from chemicals and can be copied exactly. A generic drug is an exact copy of the active drug in a brand-name medication.

Although not exact copies, biosimilars are considered as safe and effective as their parent biologic drugs. Like generics, biosimilars usually cost less than brand-name drugs.

* The reason “-xioi” appears at the end of the drug’s name is to show that the drug is distinct from similar medications that may be created in the future.

As with all medications, the cost of Zolgensma can vary. To learn about the price of Zolgensma in your area, talk with your doctor or pharmacist. What you’ll pay depends on your child’s insurance plan, your location, and the cost of the visit to the facility where your child gets their Zolgensma dose.

Before approving coverage for Zolgensma, the insurance company may require prior authorization. This means that your child’s doctor and insurance company need to communicate about the prescription before the company covers the drug. The company will review the prior authorization request and decide if the drug will be covered.

If you’re not sure whether you’ll need to get prior authorization for Zolgensma, contact your child’s insurance company.

Financial and insurance assistance

If you need financial support to pay for Zolgensma, or if you need help understanding your child’s insurance coverage, help is available.

AveXis Inc., the manufacturer of Zolgensma, offers the OneGene Program. It allows you to work with coordinators who can tell you about financial assistance available for Zolgensma. For more information and to find out if you’re eligible, call 855-441-GENE (855-441-4363) or visit the program’s website.

Generic or biosimilar version

Zolgensma isn’t available in a biosimilar form. Zolgensma is a biologic drug that’s made from living cells. Non-biologic drugs are made from chemicals and can be copied exactly. A generic drug is an exact copy of the active drug in a brand-name medication.

Biologic drugs can’t be copied exactly. Instead of generics, biologics have biosimilars. Biosimilars are considered as safe and effective as their parent biologic drugs. Like generics, biosimilars usually cost less than brand-name drugs.

Other drugs can treat spinal muscular atrophy (SMA), and some may be a better fit for your child than others. If you’re interested in finding an alternative to Zolgensma, talk with your child’s doctor. They can tell you about other medications that may work well to treat SMA.

Examples of other drugs that may be used to treat SMA include:

  • risdiplam (Evrysdi)
  • nusinersen (Spinraza)

The Food and Drug Administration (FDA) approves prescription drugs such as Zolgensma to treat certain conditions. Zolgensma may also be used off-label for other conditions. Off-label drug use means using a drug for a purpose other than what it’s been approved for by the FDA.

Zolgensma is FDA-approved to treat spinal muscular atrophy (SMA) caused by genetic changes in the SMN1 gene. For this purpose, Zolgensma is given to children less than 2 years old.

Zolgensma has certain limitations of use. Specifically:

  • Zolgensma is given as a one-time dose. Clinical studies haven’t looked at how effective the drug may be if a child receives more than one dose.
  • Zolgensma hasn’t been studied as a treatment for advanced SMA. “Advanced” means the disease has worsened. This may lead to conditions such as paralysis of the arms and legs or needing to use a ventilator to breathe.

About spinal muscular atrophy

SMA is a rare condition that damages nerve cells in the brain and spinal cord. It’s caused by SMN1 genes that are missing or aren’t working properly. Over time, the damaged nerve cells become weaker and eventually stop working. This leads to muscle weakness and trouble with basic activities such as breathing, speaking, swallowing, and walking.

There are five types of SMA:

  • SMA type 0 (the most severe form of SMA)
  • SMA type 1 (the most common form of SMA)
  • SMA type 2
  • SMA type 3
  • SMA type 4 (the least severe form of SMA, and it typically appears in adults)

Symptoms of several types of SMA appear very early in life, often before 18 months of age. These symptoms can include:

  • floppy muscles
  • inability to kick while lying on the back
  • inability to sit
  • problems eating, such as choking or trouble swallowing
  • trouble breathing
  • weak reflexes

Effectiveness for spinal muscular atrophy

Zolgensma has been found effective for treating SMA. Currently, Zolgensma is the only gene therapy available for the treatment of this condition.

For more information about how the drug performed in clinical studies, see Zolgensma’s prescribing information.

Zolgensma and children

Zolgensma is only FDA-approved to treat SMA in children less than 2 years old. It isn’t approved for use in people older than this.

Before your child receives their Zolgensma dose, their doctor will prescribe a corticosteroid (a drug that helps treat inflammation). Prednisolone is an example of a corticosteroid. Your child will start taking this drug a day before their Zolgensma dose. They’ll need to take the corticosteroid for at least 30 days.

Taking corticosteroids with Zolgensma treatment helps prevent high levels of liver enzymes, which can lead to serious liver damage.* The doctor will monitor your child’s liver function before their Zolgensma dose and for at least 3 months afterward. If your child shows any signs of liver problems, they’ll continue taking corticosteroids until their liver function improves.

* Zolgensma has a boxed warning for this side effect. A boxed warning is the most serious warning from the FDA. For more information, see “Side effect details” in the “Zolgensma side effects” section below.

Zolgensma is approved to treat spinal muscular atrophy (SMA)* in children less than 2 years old. The SMA must be caused by genetic changes in the SMN1 gene. This gene is in nerve cells and helps control muscle function.

Zolgensma contains the active ingredient onasemnogene abeparvovec. It’s a type of drug called a virus vector-based gene therapy. A virus vector contains altered genetic material that can be placed inside a person’s body.

The drug uses a virus† to carry an SMN1 gene that’s working properly. When the virus is injected into a person with SMA, the SMN1 gene that’s working properly replaces the SMN1 gene that isn’t.

The newly injected SMN1 gene only affects the genetic makeup of nerve cells. It doesn’t change the child’s DNA. Also, the virus that carries the gene isn’t active, so it doesn’t harm the child. Their body gets rid of the virus by shedding it in stool.

The way Zolgensma works in the body to treat SMA is called its mechanism of action. For a more detailed explanation of this drug’s mechanism of action, visit the drug manufacturer’s website.

* For more information about SMA, see the “Zolgensma for spinal muscular atrophy” section above.
† Specifically, Zolgensma is made with a virus called adeno-associated virus serotype 9.

How long does it take to work?

Zolgensma starts working to treat SMA as soon as it’s injected. In clinical studies of the drug, some children saw improvements in their SMA symptoms as early as 1 month after they received the drug.

If you have questions about what to expect with Zolgensma treatment, talk with your child’s doctor.

The Zolgensma dosage that your child’s doctor prescribes will depend on their body weight in kilograms (kg).

The following information describes dosages that are commonly used or recommended. Your child’s doctor will determine the best dosage to fit the needs of your child.

Drug forms and strengths

Zolgensma comes as a liquid suspension that a healthcare provider gives as an intravenous infusion (an injection into a vein over a period of time). The drug comes in one strength: 2 x 1013 vector genomes (vg)* per milliliter (mL).

* Zolgensma is a type of drug called a virus vector-based gene therapy. A virus vector contains altered genetic material that can be placed inside a person’s body. The unit of measure shown, vg per mL, indicates the number of viral particles in each mL of the drug. For more information, see the “How Zolgensma works” section above.

Dosage for spinal muscular atrophy

When the drug is used to treat spinal muscular atrophy (SMA), the usual dosage of Zolgensma is 1.1 x 1014 vg per kg* of body weight. Your child will receive only one dose of the drug. A full dosage chart can be found in the drug’s prescribing information.

* One kg is about 2.2 pounds.

What if my child misses their dose?

If your child misses their appointment to receive an infusion of Zolgensma, reschedule their appointment for as soon as possible.

To help make sure that your child doesn’t miss their appointment, try setting an alarm on your phone, marking a calendar, or downloading a reminder app.

Will my child need to use this drug long term?

No, Zolgensma isn’t meant to be used as a long-term treatment. The drug is given just one time in a single dose.

Zolgensma is given by a healthcare provider as an intravenous infusion (an injection into a vein over a period of time). The typical administration site for the drug is a vein in an arm or leg. The infusion takes an hour.

When it’s given

Zolgensma is administered as a one-time dose by a healthcare provider in a doctor’s office or clinic. The doctor will set up an appointment for your child to receive their Zolgensma infusion.

To help make sure that your child doesn’t miss their appointment, try using a medication reminder. This might include setting an alarm on your phone or downloading a reminder app.

Zolgensma can cause mild or serious side effects. The following lists contain some of the key side effects that may occur during Zolgensma treatment. These lists do not include all possible side effects.

For more information about the possible side effects of Zolgensma, talk with your child’s doctor or pharmacist. They can give you tips on how to deal with any side effects that may be concerning or bothersome.

Note: The Food and Drug Administration (FDA) tracks side effects of drugs that it has approved. If you would like to notify the FDA about a side effect of Zolgensma, you can do so through MedWatch.

Mild side effects

Mild side effects* of Zolgensma may include vomiting (see “Side effect details” below).

Most mild side effects may go away within a few days or a couple of weeks. But if they become more severe or don’t go away, talk with your child’s doctor or pharmacist.

* Zolgensma may cause other mild side effects. To learn about these, talk with your child’s doctor or pharmacist, or read Zolgensma’s important safety information.

Serious side effects

Serious side effects from Zolgensma aren’t common, but they can occur. Call your child’s doctor right away if your child has serious side effects. Call 911 or your local emergency number if their symptoms seem life threatening or if you think they’re having a medical emergency.

Serious side effects and their symptoms can include:

* High levels of troponin I are usually a sign of a recent heart attack. However, in human studies of Zolgensma, there weren’t any signs that a heart attack occurred in any children.
† For more information about this side effect, see “Side effect details” below.
‡ Zolgensma has a boxed warning for this side effect. A boxed warning is the most serious warning from the FDA.

Side effect details

Here’s some detail about certain side effects that this drug may cause.

Liver damage

Zolgensma may cause high levels of liver enzymes, which can lead to serious liver damage. Zolgensma has a boxed warning for this side effect. A boxed warning is the most serious warning from the FDA.

High levels of liver enzymes was one of the most common side effects in clinical studies of Zolgensma. Your child may have a higher risk of this side effect if they already have liver problems before receiving the drug.

Symptoms of liver damage may include:

The doctor will check your child’s liver function before the treatment and periodically for at least 3 months afterward. If your child shows any signs of liver problems, tell the doctor right away.

Low platelet levels

Zolgensma may cause low platelet levels. This wasn’t a common side effect reported in clinical studies of the drug.

Platelets are small blood cells that help form blood clots. A low platelet level can cause your child to bleed or bruise more easily than usual.

Before the treatment and periodically afterward, the doctor will check your child’s platelet level. If your child has any unexpected bruising or bleeding, tell their doctor right away.

Vomiting

Your child may experience vomiting as a side effect of their Zolgensma infusion. This was one of the most common side effects reported in clinical studies of the drug.

If your child vomits after receiving Zolgensma, they may become dehydrated. This could cause an electrolyte imbalance. (Electrolytes are substances that the body needs to function.) To avoid this, give them drinks that contain electrolytes, such as Pedialyte.

If vomiting is severe or doesn’t get better with time, talk with the child’s doctor. They can suggest ways to help relieve this side effect and make sure that your child stays healthy.

Allergic reaction

As with most drugs, some people can have an allergic reaction after receiving Zolgensma. Symptoms of a mild allergic reaction can include:

  • skin rash
  • itchiness
  • flushing (warmth or redness/deepening of skin color for a brief period of time)

A more severe allergic reaction is rare but possible. Symptoms of a severe allergic reaction can include:

  • swelling under the skin, typically in the eyelids, lips, hands, or feet
  • swelling of the tongue, mouth, or throat
  • trouble breathing

Call your child’s doctor right away if your child has an allergic reaction to Zolgensma, as the reaction could become severe. Call 911 or your local emergency number if their symptoms seem life threatening or if you think they’re having a medical emergency.

There aren’t any known interactions between Zolgensma and alcohol.

If your child uses any medications or products that contain alcohol, talk with their doctor. They can advise you on the amount of alcohol that’s safe for your child during Zolgensma treatment.

There aren’t any known interactions between Zolgensma and other medications, supplements, or foods.

The drug’s manufacturer didn’t report any interactions found in clinical studies of Zolgensma. However, this doesn’t mean that interactions can’t happen.

Before your child receives Zolgensma, talk with their doctor and pharmacist. Tell them about all the prescription, over-the-counter, and other drugs your child takes. Also tell them about any vitamins, herbs, and supplements your child uses. Sharing this information may help prevent interactions.

If you have questions about drug interactions that may affect your child, ask their doctor or pharmacist.

Zolgensma and vaccines

There aren’t any known interactions between Zolgensma and vaccines.

However, the day before your child receives Zolgensma, they’ll start treatment with a corticosteroid, such as prednisolone. (Corticosteroids are drugs used to treat inflammation.) They’ll take the corticosteroid for at least 30 days.

During their corticosteroid treatment, your child shouldn’t get any live vaccines. These contain a weakened version of the virus or bacteria responsible for the infection that the vaccine is designed to prevent.

Live vaccines don’t usually cause infections in people who have healthy immune systems. But taking corticosteroids for more than 2 weeks can weaken your child’s immune system. If they get a live vaccine while taking corticosteroids, they could have a higher risk of getting an infection from the vaccine.

Examples of live vaccines include:

Talk with your child’s doctor about whether your child’s vaccine schedule should be adjusted before they receive Zolgensma.

There haven’t been any clinical studies of Zolgensma use during pregnancy.

Zolgensma shouldn’t be given during pregnancy. The drug is only approved for use in children less than 2 years old.

The use of Zolgensma hasn’t been studied in anyone who is breastfeeding. Because the drug is only approved for use in children less than 2 years old, it isn’t likely that anyone receiving Zolgensma would be breastfeeding.

Here are answers to some frequently asked questions about Zolgensma.

Does Zolgensma cure spinal muscular atrophy?

No, Zolgensma doesn’t cure spinal muscular atrophy (SMA). There isn’t a known cure for SMA at this time.

SMA is a rare condition that damages nerve cells in the brain and spinal cord. This leads to muscle weakness and trouble with activities such as breathing, speaking, swallowing, and walking.

Clinical studies have shown Zolgensma to be effective for treating SMA caused by genetic mutations* in the SMN1 gene. The drug works by replacing an abnormal SMN1 gene with a normal SMN1 gene.

However, Zolgensma won’t reverse any effects of SMA that happened before your child received the drug. Also, your child may continue having symptoms of SMA even after they receive their Zolgensma dose. For this reason, the drug isn’t considered a cure.

If you have questions about the effectiveness of Zolgensma for treating SMA, talk with your child’s doctor.

* “Genetic mutation” refers to changes or damage to DNA that may affect how it works.

Why do I need to handle my child’s dirty diapers in a certain way during Zolgensma treatment?

This has to do with the type of drug that Zolgensma is. Zolgensma is a virus vector-based gene therapy. It works by using a virus to replace an abnormal SMN1 gene with a normal SMN1 gene. (For more information, see the “How Zolgensma works” section above.)

The virus that carries the SMN1 gene isn’t active, and it doesn’t infect or harm your child. The body gets rid of the virus by shedding it in stool. However, it isn’t known what effects the virus may have on anyone who comes into contact with it through stool. So take a few precautions during diaper changes to protect yourself and others.

If you use disposable diapers, seal each dirty diaper in a trash bag and throw it away. If you use cloth diapers, ask your doctor what they recommend during Zolgensma treatment. Also, be sure to wash your hands well after changing your child’s diaper.

Continue following these precautions for a month after your child has had their Zolgensma infusion. After that, their body should be rid of the virus, and you can go back to diapering as usual.

If you have questions about handling diapers after your child has had Zolgensma, talk with their doctor.

Will my child need to have lab tests done with Zolgensma treatment?

Yes, your child will need several lab tests before and after their Zolgensma dose.

Zolgensma is a gene therapy that contains a virus called adeno-associated virus serotype 9 (AAV9).* Before prescribing Zolgensma, your child’s doctor will check the level of anti-AAV9 antibodies (proteins that work against the activity of AAV9) in your child’s blood. If the level indicates that Zolgensma may not work as well for your child, the doctor may recommend another treatment.

Zolgensma may cause or worsen several other health conditions. The doctor will likely perform a few other tests before your child receives the drug and periodically afterward.

Below are other tests that your child’s doctor may perform:

If you have questions about tests that your child will need before or after Zolgensma treatment, talk with their doctor.

* For more information, see the “How Zolgensma works” section above.

This drug comes with several precautions.

FDA warning: Liver damage

This drug has a boxed warning. This is the most serious warning from the Food and Drug Administration (FDA). A boxed warning alerts doctors and patients about drug effects that may be dangerous.

Liver problems. Zolgensma may cause high levels of liver enzymes, which can lead to serious liver damage. Your child may have a higher risk for this if they already have liver problems before using the drug.

To help prevent liver damage, your child’s doctor will prescribe a corticosteroid (a drug that helps treat inflammation). Your child will start taking this drug the day before their Zolgensma dose. They’ll need to take the corticosteroid for at least 30 days.

The doctor will monitor your child’s liver function before their dose and for at least 3 months after. If your child shows any signs of liver problems, they’ll continue taking corticosteroids until their liver function improves.

Other precautions

Before your child receives Zolgensma, talk with their doctor about their health history. Zolgensma may not be right for your child if they have certain medical conditions or other factors affecting their health. These include:

  • Respiratory infection. It may not be safe for your child to use Zolgensma while they have a respiratory infection. (Examples include the common cold or the flu.) Some respiratory infections may be serious, such as an infection with the respiratory syncytial virus (RSV). Be sure to tell your child’s doctor if your child shows any symptoms of a respiratory infection before they receive Zolgensma. Symptoms can include a fever, a runny nose, sneezing, and a sore throat. The doctor may reschedule your child’s Zolgensma dose until after their infection has healed.
  • Allergic reaction. If your child has had an allergic reaction to any of Zolgensma’s ingredients, they shouldn’t receive the drug. Ask your child’s doctor what other medications are better options.
  • Pregnancy. Zolgensma shouldn’t be used during pregnancy. For more information, see the “Zolgensma and pregnancy” section above.
  • Breastfeeding. Zolgensma shouldn’t be used while breastfeeding. For more information, see the “Zolgensma and breastfeeding” section above.

Note: For more information about the potential negative effects of Zolgensma, see the “Zolgensma side effects” section above.

Disclaimer: Medical News Today has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or other healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.