7 mins read

Overview: Genglycos is a gene therapy that is a one-time infusion into a blood vessel. It is used to treat certain people with a rare inherited disorder called glycogen storage disease type Ia. It works by delivering a healthy copy of a gene that is needed to make an enzyme that keeps blood sugar stable. The most common side effects from Genglycos are nausea and increased liver enzymes. You will likely receive medicine to reduce the risk of liver damage. Be sure to keep all appointments with your health care provider before and after receiving Genglycos.

Uses

What is Genglycos used for?

Genglycos (pariglasgene brecaparvovec-opnr) is used, along with dietary changes, for certain people with a rare inherited condition called glycogen storage disease type Ia (GSDIa). People who have GSDIa have a faulty G6PC gene, which makes them unable to make glucose-6-phosphatase (G6Pase). G6Pase is an enzyme that keeps blood sugar stable. 

Genglycos may also be used for other conditions as determined by your health care provider.

How does Genglycos work (mechanism of action)?

Glycogen storage disease type Ia (GSDIa) is an inherited disorder caused by a faulty G6PC gene. People who have GSDIa are not able to make enough glucose-6-phosphatase (G6Pase), an enzyme needed to release stored sugar to keep blood sugar stable. Because that sugar cannot be released, it builds up as glycogen and fat, mainly in the liver and kidneys. If the person goes too long without eating, they can have very low blood sugar.

Genglycos is a gene therapy. It treats the cause of GSDIa, instead of just the symptoms. It uses a modified virus (called adeno-associated virus, or AAV8) to reach liver cells. Inside these cells, it carries a healthy copy of the G6PC gene, along with the natural “switches” that tells the body when and how much G6Pase to make. Liver cells use this to make normal G6Pase, which helps keep blood sugar stable. 

How is Genglycos supplied (dosage forms)?

Genglycos is available in an injectable form that is given by a health care provider.

How should I store Genglycos?

Genglycos is usually given by a health care provider in a hospital or clinic. You will not store it at home.

Side Effects

What are the most common side effects of Genglycos?

The most common side effects of Genglycos are listed below. Tell your health care provider if you have any of these side effects that bother you.

There may be other side effects of Genglycos that are not listed here. Contact your health care provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088 (800-332-1088). In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of Genglycos?

While less common, the most serious side effects of Genglycos are described below, along with what to do if they happen.

Severe Allergic Reactions. Genglycos may cause allergic reactions, which can be serious. Get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching or skin rash
  • Bumps on the skin called hives that can be red, pink, white, or brown depending on your skin tone
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Infusion Reactions. Genglycos can cause reactions that can be serious when it is given to you. Your infusion may need to be slowed or paused if you have these reactions. Tell your health care provider right away if you have any of the following symptoms during or after your infusion.

  • Hives
  • Redness of your face and neck
  • Low blood pressure or high blood pressure
  • Trouble breathing or shortness of breath
  • Chest tightness
  • Nausea or vomiting
  • Headache
  • Stomach pain
  • Lightheadedness
  • Fever, chills, or shivering
  • Rash

Liver Damage. Liver damage, also called hepatotoxicity, can happen when using Genglycos. You will likely receive medicine to reduce your risk of liver damage after your dose. Keep all appointments, including those for lab work. Your health care provider will use these lab results to watch for liver problems. Call your health care provider right away if you have any of the following symptoms of liver damage.

  • Nausea or vomiting
  • Stomach or belly pain
  • Fever
  • Weakness or unusual tiredness
  • Itching
  • Loss of appetite
  • Light-colored poop
  • Dark-colored urine (pee)
  • Your skin or the whites of your eyes turning yellowish in color (also called jaundice)

Reduced Adrenal Function. After your Genglycos infusion, you will take a corticosteroid medicine for a period of time and then slowly lower the dose. Corticosteroids can cause your body’s adrenal glands to stop making as much cortisol (the stress hormone). This is known as adrenal insufficiency. This risk is present while you take the corticosteroid and as the dose is reduced, which is why you should not stop the corticosteroid suddenly. Adrenal insufficiency can get worse if your body is under stress because of fever, surgery, or trauma. Tell your health care provider right away if you miss a dose of corticosteroid, if you throw up the dose, or if you have any of the following symptoms of adrenal insufficiency.

Tumors. Because of how gene therapies like Genglycos work, there is a theoretical risk that a tumor could develop. This risk has not been proven. As a precaution, your health care provider may monitor you over the long term for possible tumors. Tell your health care provider about any new symptoms that you may get. If you get a tumor while using Genglycos, you should also contact the drugmaker at 888-756-8657.

Warnings & Precautions

Who should not use Genglycos?

Allergies to Ingredients. People who are allergic to any of the following should not use Genglycos.

  • Genglycos
  • Pariglasgene brecaparvovec-opnr
  • Any of the ingredients in the specific product dispensed

Your pharmacist can tell you all of the ingredients in Genglycos.

Liver Problems. Genglycos should not be used if your liver is not working as well as it should be, including if you have severe liver fibrosis (scarring) or cirrhosis. Your health care provider will likely do tests to see if your liver is working well enough to use this medicine.

What should I know about Genglycos before using it?

Genglycos is usually given by a health care provider in a hospital or clinic. It is given as a one-time infusion into a vein (IV). 

You will likely receive medicines before and after your dose of Genglycos to reduce your risk of side effects. You should take these medicines as recommended by your health care provider. Talk to your health care provider if you have concerns. 

It is very important to keep all appointments with your health care provider before and after receiving Genglycos. These appointments help your health care provider make sure the treatment is safe and working well for you.

If you are able to get someone pregnant, you and your partner should use effective birth control for at least 6 months after you receive Genglycos. You should also not donate semen for 6 months after receiving Genglycos. Talk to your health care provider if you have concerns. If you are able to get pregnant, see the Pregnancy section for more details.

After receiving Genglycos, small amounts of the vector (an inactive virus used to carry the G6PC gene) can be found in blood, pee, poop, and saliva for a short time. This is normal and does not mean you have or are spreading an infection. As a precaution, practice good hand hygiene and place any soiled materials in a sealed bag before throwing them away. You can throw the sealed bag in the regular trash. These precautions are usually needed for 3 months after receiving Genglycos.

What should I tell my health care provider before using Genglycos?

Tell your health care provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them know if Genglycos is right for you.

In particular, make sure that you discuss any of the following.

Vaccines. Talk with your health care provider about any vaccines that you may need. You should not receive certain vaccines for some time before or after receiving Genglycos. Tell your health care provider about any vaccines you have recently received or have scheduled.

Liver Problems. Tell your health care provider if you have liver problems, including liver infections, such as viral hepatitis. Genglycos may cause liver damage. Your risk may be higher if you have liver problems. 

Pregnancy. You should not use Genglycos if you are pregnant. It is not known if or how Genglycos could affect pregnancy or harm a fetus. If you are able to get pregnant, you should use effective birth control for at least 12 months after receiving Genglycos. Tell your health care provider if you are pregnant or plan to become pregnant.

Breastfeeding. It is not known if Genglycos passes into breast milk. Tell your health care provider if you are breastfeeding or plan to breastfeed. Your health care provider will let you know if you should receive Genglycos while breastfeeding.

How can I get more information about Genglycos?

For more information about Genglycos, you can visit the drugmaker’s website at www.genglycos.com or call them at 888-756-8657.

Interactions

Does Genglycos interact with foods or drinks?

There are no known interactions between Genglycos and foods or drinks.

Both Genglycos and alcohol can cause liver problems. It is best to limit the amount of alcohol you drink.

Does Genglycos interact with other medicines (drug interactions)?

You may not be able to receive certain vaccines or take certain medicines or supplements before or after receiving Genglycos. Always tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

Does interact with other drugs you are taking?

Enter your medication into the WebMD interaction checker

Overdose/Missed Dose

What should I do if I accidentally use too much Genglycos?

If you or someone else has used too much Genglycos, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

What should I do if I miss a dose of Genglycos?

Genglycos is a single-use medicine, meaning you only get one dose. It is usually given by a health care provider in a hospital or clinic. Your health care provider will make sure you receive Genglycos as scheduled.

If you miss your appointment to get your Genglycos dose, call to make another appointment as soon as possible.