Fyarro (sirolimus protein-bound particles)
An approved treatment for PEComa.
Drug facts
The same compound appears under different names depending on the context. Here is how to identify Sirolimus protein-bound particles wherever you encounter it, plus the key facts at a glance.
- Generic name
- Sirolimus protein-bound particles
- Brand name
- Fyarro
- Development codes
- ABI-009, nab-sirolimus
- Drug class
- mTOR inhibitor
- Manufacturer
- Aadi Bioscience (owned by KAKEN Pharmaceutical since March 2025)
- How it's taken
- Intravenous infusion
An IV infusion for adults with malignant PEComa that has spread or cannot be removed by surgery, given on days 1 and 8 of each 21-day cycle. Approved November 22, 2021, it is the only FDA-approved drug for malignant PEComa.
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Where Sirolimus protein-bound particles fits
The standard first medicine for malignant PEComa that cannot be removed by surgery. Oral mTOR blockers such as sirolimus or everolimus are sometimes used off label.
How Sirolimus protein-bound particles works
Sirolimus blocks mTOR, a switch inside cells that drives growth. In many PEComas this switch is stuck on, often because of a change in the TSC1 or TSC2 gene. Fyarro binds sirolimus to albumin, a natural blood protein, so it can be given by vein. In animal studies this form put more sirolimus into tumors than the same weekly dose taken by mouth.
Side effects and safety
- Mouth sores. Occurred in 79% of people, 18% severe, most often within the first 8 weeks. The dose is held or lowered if they get bad.
- Low blood counts. Low red cells occurred in 68%, and low platelets and low infection-fighting white cells in 35% each.
- Infections. Occurred in 59%, mostly urinary, sinus and upper airway infections; 12% were severe. Tell the care team about fever or chills.
- Low potassium and high blood sugar. Low potassium occurred in 44% and high blood sugar in 12%. Both are checked with blood tests.
- Lung inflammation. Occurred in 18%, all mild or moderate. Report a new cough, chest pain or shortness of breath.
- Bleeding. Occurred in 24%, with severe bleeding in 2.9% and fatal bleeding in 2.9%, which was 1 person.
- Allergic reactions. People are watched for at least 2 hours after the first infusion.
- Pregnancy, fertility and vaccines. Can harm an unborn baby, so birth control is used during treatment and for 12 weeks after. It may affect fertility, and live vaccines are avoided.
- Blood counts before starting, every 2 months for the first year and every 3 months after
- Potassium and fasting blood sugar before starting, then blood sugar every 3 months, more often with diabetes
- Watching for allergic reactions for at least 2 hours after the first infusion
- A pregnancy test before starting for people who can become pregnant
Fyarro has no boxed warning. It should not be used by people who have had a severe allergic reaction to sirolimus, similar drugs or albumin. In the AMPECT trial, mouth sores occurred in 79% of people and were severe in 18%. They usually started within the first 8 weeks. Low red blood cell counts occurred in 68% and infections in 59%.
Low potassium occurred in 44%, lung inflammation in 18% and bleeding in 24%. One person died from bleeding in the stomach. Serious side effects happened in 41% of the 34 people treated, and 9% stopped Fyarro because of side effects.
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 Sirolimus protein-bound particles
100mg/m² by IV infusion over 30 minutes on days 1 and 8 of each 21-day cycle, so 2 weeks on and 1 week off. It continues until the tumor grows or side effects become too hard to manage. The dose is lowered to 75mg/m² for mild liver impairment and 56mg/m² for moderate liver impairment, and Fyarro is avoided with severe liver impairment.
It is also lowered to 56mg/m² with some other medicines that raise sirolimus levels. Avoid grapefruit and grapefruit juice, and tell the care team about every medicine, because many drugs change sirolimus levels.
Availability and cost
Only available as the brand-name product.
Help paying for Fyarro
Pick your insurance to see which help fits. Drugmaker copay cards can't be used with Medicare, Medicaid or TRICARE; charity funds are the usual route there.
- Copay help
People with commercial or private insurance may get help with out-of-pocket costs for FYARRO up to $25,000 a year through the AadiAssist Co-Pay Support Program. Ask your doctor to enroll you.
For: private insurance · source - Free medicine program
The AadiAssist Patient Assistance Program provides FYARRO at no cost to eligible uninsured or underinsured patients. Your doctor gives you the application and submits it.
For: no insurance, underinsured · source - Bridge or quick-start supply
If insurance approval is delayed or there is a coverage problem, the Temporary Supply Program may provide a limited supply for up to 60 days to start or stay on treatment. Ask AadiAssist whether your insurance qualifies.
For: private insurance, Medicare, Medicaid, TRICARE, no insurance, underinsured · source - Insurance and case manager help
AadiAssist answers insurance questions at 1-855-AADIHUB (1-855-223-4482), Monday to Friday 8 AM to 8 PM ET.
For: private insurance, Medicare, Medicaid, TRICARE, no insurance, underinsured · source
Good to know: AadiAssist is run by Aadi Bioscience, a KAKEN Pharmaceutical company since March 2025. Terms and conditions apply.
No charity fund for this condition is open right now. Funds reopen when they receive new donations; the foundations let you sign up to be told when one opens.
Clinical trial results
AMPECT (NCT02494570) was a single-arm Phase 2 trial, meaning everyone received Fyarro and there was no comparison group. Among 31 people with malignant PEComa, tumors shrank by at least 30% in 12 people, or 39%. Another 52% had stable disease. Responses came quickly: of the 12 people who responded, 8 had responded by week 6. In the final 2024 update, the median response lasted 39.7 months, median progression-free survival was 10.6 months and median overall survival was 53.1 months.
Among people whose tumors had a TSC2 gene change, 8 of 9 responded, against 2 of 16 without one.
Development history
Aadi Bioscience developed Fyarro under the code name ABI-009. The FDA approved it on November 22, 2021 based on the AMPECT trial. It was the first approved treatment for malignant PEComa and had priority review, fast track, breakthrough therapy and orphan drug status. In March 2025 Aadi sold the Fyarro business and the Aadi Bioscience name to Japan's KAKEN Pharmaceutical. The former parent company became Whitehawk Therapeutics.
Explore PEComa trials
Common questions about Sirolimus protein-bound particles
▸What is Sirolimus protein-bound particles (Fyarro)?
An IV infusion for adults with malignant PEComa that has spread or cannot be removed by surgery, given on days 1 and 8 of each 21-day cycle. Approved November 22, 2021, it is the only FDA-approved drug for malignant PEComa.
▸How does Sirolimus protein-bound particles work?
Sirolimus blocks mTOR, a switch inside cells that drives growth. In many PEComas this switch is stuck on, often because of a change in the TSC1 or TSC2 gene. Fyarro binds sirolimus to albumin, a natural blood protein, so it can be given by vein. In animal studies this form put more sirolimus into tumors than the same weekly dose taken by mouth.
▸What are the side effects of Sirolimus protein-bound particles?
Fyarro has no boxed warning. It should not be used by people who have had a severe allergic reaction to sirolimus, similar drugs or albumin. In the AMPECT trial, mouth sores occurred in 79% of people and were severe in 18%. They usually started within the first 8 weeks. Low red blood cell counts occurred in 68% and infections in 59%. Low potassium occurred in 44%, lung inflammation in 18% and bleeding in 24%. One person died from bleeding in the stomach. Serious side effects happened in 41% of the 34 people treated, and 9% stopped Fyarro because of side effects.
▸How is Sirolimus protein-bound particles taken?
100mg/m² by IV infusion over 30 minutes on days 1 and 8 of each 21-day cycle, so 2 weeks on and 1 week off. It continues until the tumor grows or side effects become too hard to manage. The dose is lowered to 75mg/m² for mild liver impairment and 56mg/m² for moderate liver impairment, and Fyarro is avoided with severe liver impairment. It is also lowered to 56mg/m² with some other medicines that raise sirolimus levels. Avoid grapefruit and grapefruit juice, and tell the care team about every medicine, because many drugs change sirolimus levels.
▸Is Sirolimus protein-bound particles FDA approved?
Yes, Sirolimus protein-bound particles (Fyarro) is FDA approved (2021) for the treatment of PEComa.
▸How is Fyarro given?
As a 30-minute IV infusion on days 1 and 8 of each 21-day cycle, so 2 weeks on and 1 week off. It continues as long as it keeps the tumor in check and side effects stay manageable.
▸How well does Fyarro work for PEComa?
In the AMPECT trial of 31 people, tumors shrank in 39% and held steady in another 52%. The median response lasted 39.7 months, and people whose tumors had a TSC2 gene change responded most often, 8 of 9.
▸Is Fyarro the same as sirolimus pills?
It has the same active ingredient, but Fyarro binds sirolimus to albumin and is given by vein. Sirolimus pills (Rapamune) are approved for organ transplant and for LAM, a related lung condition, but not for malignant PEComa.
▸Who makes Fyarro now?
Aadi Bioscience, which has been owned by Japan's KAKEN Pharmaceutical since March 2025. Its AadiAssist program helps with insurance, co-pays and free drug for eligible patients.
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 · 2026-09. FYARRO (sirolimus protein-bound particles for injectable suspension) (albumin-bound): prescribing information. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=0f9bb784-53e2-46f9-a65d-1c6c2a230eaf
- U.S. Food and Drug Administration · 2021-11-22. FDA approves sirolimus protein-bound particles for malignant perivascular epithelioid cell tumor. https://www.fda.gov/drugs/resources-information-approved-drugs/fda-approves-sirolimus-protein-bound-particles-malignant-perivascular-epithelioid-cell-tumor
- Journal of Clinical Oncology · 2021-11-20. nab-Sirolimus for Patients With Malignant Perivascular Epithelioid Cell Tumors. https://pubmed.ncbi.nlm.nih.gov/34637337/
- Journal of Clinical Oncology · 2024-05-01. Phase II Trial of nab-Sirolimus in Patients With Advanced Malignant PEComa (AMPECT): Long-Term Efficacy and Safety Update. https://pubmed.ncbi.nlm.nih.gov/38427923/
- PR Newswire · 2025-03-26. Whitehawk Therapeutics completes sale of Aadi subsidiary to Kaken Pharmaceuticals. https://www.prnewswire.com/news-releases/whitehawk-therapeutics-completes-strategic-transformation-with-successful-closing-of-sale-of-aadi-subsidiary-to-kaken-pharmaceuticals-302411424.html
- Aadi Bioscience. AadiAssist patient support services. https://www.aadiassist.com/patient/services