Asparaginase (pegaspargase and others)
Say it: peg-ASS-par-jays · Brand names: Oncaspar, Asparlas, Rylaze
Asparaginase is a medicine that starves leukemia cells by removing a building block they need to live.
What it is
Leukemia cells cannot make enough of a protein building block called asparagine, so they take it from the blood. Asparaginase is an enzyme that breaks down asparagine in the blood. Without it, the leukemia cells cannot make proteins and they die. Pegaspargase (Oncaspar) and calaspargase pegol (Asparlas) come from E. coli bacteria and last a long time. Rylaze comes from a different source and is used if someone has an allergic reaction to the other types.
Often used for
- acute lymphoblastic leukemia (ALL), as part of a combination of medicines
- lymphoblastic lymphoma
How you get it
Asparaginase is given as a shot into a muscle or through a vein (IV) at the clinic or hospital. Pegaspargase and calaspargase are often given every 2 to 3 weeks during certain parts of treatment. Rylaze is given more often, such as every 2 days or 3 times a week. Your schedule may be different.
Common side effects and what helps
- Allergic reactions, such as rash, itching, or hives. You will be watched for about an hour after each dose.
- Nausea, vomiting, or less appetite. Small, low-fat meals may help.
- High blood sugar. Your team will check your sugar.
- Changes in liver blood tests. Your team will check these often.
- Feeling tired. Rest when you need to.
- Belly pain. Tell your team right away if it is bad.
Call your care team right away if you have
- Trouble breathing, swelling of the face or throat, wheezing, or hives during or after a dose
- Bad belly pain that may spread to the back, with or without vomiting
- A bad headache, seizure, trouble speaking, weakness on one side, or vision changes
- Pain, swelling, or warmth in an arm or leg, or sudden shortness of breath or chest pain
- Unusual bleeding or bruising
- Yellow skin or eyes, or very dark urine
- A fever of 100.4 degrees Fahrenheit (38 degrees Celsius) or higher, or chills
Before you start, tell your team
- If you are pregnant, may become pregnant, or are breastfeeding
- If you have ever had pancreatitis, a serious blood clot, or serious bleeding
- If you have had a reaction to asparaginase before
- If you have diabetes or liver problems
- All the medicines, vitamins, and herbal products you take
Good to know
- Serious allergic reactions can happen. If you react to one type, your team may switch you to another, such as Rylaze.
- It can cause inflammation of the pancreas (pancreatitis), which can be serious.
- It can cause blood clots, including in the brain, and bleeding. Your team will check clotting blood tests.
- It can cause liver problems and high blood sugar. You will have blood tests often.
- It can make hormonal birth control pills work less well. Use another type of birth control, as your team tells you.
Questions to ask
- Which type of asparaginase will I get, and how often?
- How will you watch for allergic reactions?
- Are there foods I should limit, such as fatty foods?
- What signs of pancreatitis or blood clots should I watch for?
Part of these treatment plans
Side effect guides
- Fatigue (tiredness)
- Nausea and vomiting
- Appetite loss and weight loss
- Skin rash (including EGFR-inhibitor rash)
- Pain
Sources
Quick answers
- What is Asparaginase (pegaspargase and others)?
- Asparaginase is a medicine that starves leukemia cells by removing a building block they need to live. Brand names: Oncaspar, Asparlas, Rylaze.
- What is Asparaginase (pegaspargase and others) used for?
- acute lymphoblastic leukemia (ALL), as part of a combination of medicines; lymphoblastic lymphoma.
- How is Asparaginase (pegaspargase and others) given?
- Asparaginase is given as a shot into a muscle or through a vein (IV) at the clinic or hospital. Pegaspargase and calaspargase are often given every 2 to 3 weeks during certain parts of treatment. Rylaze is given more often, such as every 2 days or 3 times a week. Your schedule may be different.
- What are the common side effects of Asparaginase (pegaspargase and others)?
- Allergic reactions, such as rash, itching, or hives. Nausea, vomiting, or less appetite. High blood sugar. Changes in liver blood tests. Feeling tired. Belly pain.
- When should I call my care team while taking Asparaginase (pegaspargase and others)?
- Trouble breathing, swelling of the face or throat, wheezing, or hives during or after a dose; Bad belly pain that may spread to the back, with or without vomiting; A bad headache, seizure, trouble speaking, weakness on one side, or vision changes; Pain, swelling, or warmth in an arm or leg, or sudden shortness of breath or chest pain; Unusual bleeding or bruising; Yellow skin or eyes, or very dark urine; A fever of 100.4 degrees Fahrenheit (38 degrees Celsius) or higher, or chills.
- Which chemotherapy plans include Asparaginase (pegaspargase and others)?
- C10403 (CALGB 10403).
Last updated: 2026-10-27. Medically reviewed by Veli Bakalov, MD, medical oncologist (October 2026). General education from Step by Step, the patient portal of HemeOncBuddy.