Xenpozyme (olipudase alfa-rpcp)
An approved treatment for Niemann-Pick Disease.
Drug facts
The same compound appears under different names depending on the context. Here is how to identify Olipudase alfa-rpcp wherever you encounter it, plus the key facts at a glance.
- Generic name
- Olipudase alfa-rpcp
- Brand name
- Xenpozyme
- Development code
- GZ402665
- Drug class
- Enzyme replacement therapy
- Manufacturer
- Sanofi
- How it's taken
- Given as an IV infusion every 2 weeks, usually at an infusion center, with the dose based on body weight.
The first and only FDA-approved treatment for acid sphingomyelinase deficiency (ASMD), once called Niemann-Pick disease type A and B, given as an IV infusion every 2 weeks. It treats the effects outside the brain, such as an enlarged spleen and liver and breathing problems, in adults and children.
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Where Olipudase alfa-rpcp fits
The only FDA-approved treatment for ASMD, once called Niemann-Pick type A and B. Niemann-Pick type C is a separate disease, treated with Miplyffa (arimoclomol) or Aqneursa (levacetylleucine).
How Olipudase alfa-rpcp works
People with ASMD have changes in the SMPD1 gene, so they make too little acid sphingomyelinase. Without it, a fatty substance called sphingomyelin builds up inside cells, swelling the spleen and liver and scarring the lungs. Olipudase alfa replaces the missing enzyme so cells can break that fat down. It is not expected to reach the brain, so it is not expected to help the nerve damage of the infant form, once called type A.
Side effects and safety
- Infusion reactions. These affected about 75% of children and 50% of adults in the trials. The doctor may give an antihistamine, fever reducer or steroid beforehand.
- Raised liver enzymes. Liver tests are done within a month before starting and within 3 days before every infusion while the dose is being raised, and the dose is held or lowered if they climb.
- Harm to an unborn baby. Pregnancy is checked before starting, and birth control is used during treatment and for 14 days after the last dose if it is stopped.
- Liver enzymes before starting and before every infusion while the dose is being raised
- Pregnancy test before starting
- Watch for allergic and infusion reactions during and after each infusion
Xenpozyme has a boxed warning for serious allergic reactions, including anaphylaxis, which happened in 2 of the 8 children in the trials. Infusion reactions affected about half of adults and three-quarters of children in the trials, and 1 child had a severe reaction. Liver enzymes rose in about 13% of people while the dose was being raised, usually 1-2 days after an infusion.
It may harm an unborn baby, so pregnancy is checked first and birth control is used during treatment. In the adult trial, the most common side effects were headache, cough, diarrhea, low blood pressure and red eyes.
This is not a complete list of side effects. Talk to your doctor or pharmacist about what to expect and when to seek medical attention.
Taking Olipudase alfa-rpcp
Given as an IV infusion every 2 weeks, usually at an infusion center, with the dose based on body weight. The dose starts very low and is raised in steps over about 14 weeks for adults and 16 weeks for children, to a maintenance dose of 3mg/kg. Missing doses can mean repeating or restarting the step-up schedule. Home infusion with a nurse may be possible later for people who handle the maintenance dose well.
Availability and cost
Only available as the brand-name product.
Help paying for Xenpozyme
With private insurance, the drugmaker's copay card can lower what you pay for Xenpozyme. Drugmaker copay cards can't be used with Medicare, Medicaid or TRICARE, but charity funds often can. Of the 5 charity funds for Niemann-Pick Disease, 4 were open on October 19, 2026. Without insurance, you can apply to the drugmaker's free medicine program, which sets its own eligibility rules. Pick your insurance below to see which offers fit you.
- Copay help
Covers out-of-pocket drug costs and certain infusion-related charges for commercially insured patients, up to the program maximum. Not valid with Medicaid, Medicare, VA, DOD, TRICARE or other federal or state programs, including state pharmaceutical assistance programs.
For: private insurance · source - Free medicine program
Patient Assistance Program provides Xenpozyme at no cost, as a temporary solution, to eligible patients without health insurance or who cannot get it under their plan.
For: no insurance, underinsured · source
Good to know: Call CareConnectPSS at 1-800-745-4447, weekdays 8am-6pm ET. The program maximum is not stated on the page.
Charity funds for Niemann-Pick Disease
- From a charity · NORD RareCareASMD Medical Assistance fundOpen
Pays for: Medical and medication costs.
The foundation says: “Accepting Applications” - From a charity · NORD RareCareASMD Premium Copay fundOpen
Pays for: Insurance premiums and copays.
The foundation says: “Accepting Applications” - From a charity · The Assistance FundAcid Sphingomyelinase Deficiency (ASMD) fundOpen
Pays for: Copays, coinsurance, deductibles and other health-related expenses.
- From a charity · The Assistance FundNiemann-Pick Disease Type C (NPC) fundOpen
Pays for: Copays, coinsurance, deductibles and other health-related expenses.
- From a charity · National Niemann-Pick Disease FoundationFamily Assistance and Support Program (FASP) fundApply directly
Pays for: Equipment, durable medical goods, utilities, home and car adaptations, rent or mortgage (per 12 months; not copays, premiums or travel), up to $1,000 per year.
The foundation says: “Status not shown on page”
Access and eligibility
Approved for the effects of ASMD outside the brain in adults and children, with no lower age limit. It is not expected to treat the brain and nerve problems of the infant form, once called Niemann-Pick type A. It does not treat Niemann-Pick type C, which is a different disease with different medicines.
Source: Sanofi CareConnect Personalized Support Services
Access program details are provided for informational purposes and may vary based on insurance coverage, geographic location, and individual circumstances. Confirm current eligibility directly with the manufacturer or your specialty pharmacy.
Clinical trial results
In ASCEND (NCT02004691), adults with ASMD were randomly assigned to Xenpozyme or placebo for 52 weeks, with 31 analyzed. How well the lungs pass oxygen into the blood improved 23.9% on Xenpozyme against 3.0% on placebo. Spleen volume shrank 39% on Xenpozyme and stayed about the same on placebo. Both results had less than a 1 in 1,000 chance of being a fluke. In ASCEND-Peds (NCT02292654), the 8 children whose results are in the FDA label saw their spleen shrink 47% and liver shrink 38% after 52 weeks.
Development history
Sanofi developed olipudase alfa, and the FDA approved it on August 31, 2022 for adults and children with ASMD, the first treatment for the disease. The label also reports that a 2-year-old died after a starting dose higher than recommended, which is why the slow step-up schedule matters.
Explore Niemann-Pick Disease trials
Other Niemann-Pick Disease treatments
ASMD has 1 FDA-approved treatment, Xenpozyme (olipudase alfa), approved August 31, 2022 for adults and children. Before it, care focused on managing the spleen, liver, lungs, cholesterol and growth. Niemann-Pick type C, a different disease that shares the old name, has its own approved drugs, Miplyffa and Aqneursa.
Common questions about Olipudase alfa-rpcp
▸What is Olipudase alfa-rpcp (Xenpozyme)?
The first and only FDA-approved treatment for acid sphingomyelinase deficiency (ASMD), once called Niemann-Pick disease type A and B, given as an IV infusion every 2 weeks. It treats the effects outside the brain, such as an enlarged spleen and liver and breathing problems, in adults and children.
▸How does Olipudase alfa-rpcp work?
People with ASMD have changes in the SMPD1 gene, so they make too little acid sphingomyelinase. Without it, a fatty substance called sphingomyelin builds up inside cells, swelling the spleen and liver and scarring the lungs. Olipudase alfa replaces the missing enzyme so cells can break that fat down. It is not expected to reach the brain, so it is not expected to help the nerve damage of the infant form, once called type A.
▸What are the side effects of Olipudase alfa-rpcp?
Xenpozyme has a boxed warning for serious allergic reactions, including anaphylaxis, which happened in 2 of the 8 children in the trials. Infusion reactions affected about half of adults and three-quarters of children in the trials, and 1 child had a severe reaction. Liver enzymes rose in about 13% of people while the dose was being raised, usually 1-2 days after an infusion. It may harm an unborn baby, so pregnancy is checked first and birth control is used during treatment. In the adult trial, the most common side effects were headache, cough, diarrhea, low blood pressure and red eyes.
▸How is Olipudase alfa-rpcp taken?
Given as an IV infusion every 2 weeks, usually at an infusion center, with the dose based on body weight. The dose starts very low and is raised in steps over about 14 weeks for adults and 16 weeks for children, to a maintenance dose of 3mg/kg. Missing doses can mean repeating or restarting the step-up schedule. Home infusion with a nurse may be possible later for people who handle the maintenance dose well.
▸Is Olipudase alfa-rpcp FDA approved?
Yes, Olipudase alfa-rpcp (Xenpozyme) is FDA approved (2022) for the treatment of Niemann-Pick Disease.
▸Is Xenpozyme for Niemann-Pick type C?
No, it treats ASMD, which was once called Niemann-Pick type A and B. Niemann-Pick type C is a different disease caused by different genes, and it is treated with Miplyffa or Aqneursa.
▸Why does Xenpozyme start at such a low dose?
Raising the dose slowly over about 14-16 weeks lowers the risk of infusion reactions and liver enzyme rises. A 2-year-old died after a starting dose higher than recommended, so the step-up schedule is followed closely.
▸Can Xenpozyme be given at home?
The first infusions happen in a clinic or infusion center. Once someone is on the maintenance dose and has no reactions, the label says home infusion with a healthcare provider may be considered.
Sources and references
Every factual claim on this page is drawn from the public sources listed below. Click any reference to open the original document.
- U.S. National Library of Medicine, DailyMed · 2025-12-11. XENPOZYME (olipudase alfa-rpcp) for injection: prescribing information. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=01a910ee-a33e-4be3-ac41-322d64c34311
- U.S. Food and Drug Administration · 2022-08-31. BLA 761261 approval letter. https://www.accessdata.fda.gov/drugsatfda_docs/appletter/2022/761261Orig1s000ltr.pdf
- ClinicalTrials.gov. ASCEND: olipudase alfa in adults with acid sphingomyelinase deficiency. https://clinicaltrials.gov/study/NCT02004691
- ClinicalTrials.gov. ASCEND-Peds: olipudase alfa in children with acid sphingomyelinase deficiency. https://clinicaltrials.gov/study/NCT02292654
- Sanofi. Financial assistance programs. https://www.careconnectpss.com/financial-assistance/financial-assistance-programs