Injection Treatment When the Body Makes Too Many Eosinophils

For people living with hypereosinophilic syndrome (HES), the practical question is rarely “is there a science paper?” It is “can my specialist prescribe this, and who pays?” In early August 2026, that second question changed in Canada — but only halfway.

Health Canada has authorized Fasenra (benralizumab), already used here for severe eosinophilic asthma and for eosinophilic granulomatosis with polyangiitis (EGPA), as an add-on to standard therapy for HES in people aged 12 years and older who do not have an identifiable non-hematologic secondary cause. The authorized Canadian Product Monograph is dated 5 August 2026 (control number 301480). Health Canada’s Drug Product Database lists that same monograph date on the marketed product (DIN 02473232, Fasenra prefilled syringe; DIN 02496135, Fasenra Pen). AstraZeneca Canada announced a Notice of Compliance on 10 August 2026; that company date is noted, but it is not the source used to confirm the label.

This is the second IL-5-pathway biologic with a Canadian HES indication. Nucala (mepolizumab) has been authorized here for adult HES since 2021. Fasenra’s label is broader on age (adolescents 12 and older, if they weigh at least 40 kg) and does not require a six-month disease-duration floor in the wording Health Canada authorized. None of that is the same as public funding.

Where this is taking place

NATRON (NCT04191304) ran at 40 sites in 15 countries: Argentina, Austria, Belgium, China, Denmark, France, Germany, India, Israel, Japan, the Netherlands, Poland, South Korea, the United Kingdom, and the United States. Canada is not on that published list. Status: active but no longer taking new patients (results posted; estimated completion 28 February 2027). Ages 12+. Not adult-only. Not “closed.”

A separate paediatric trial, CLIPS (NCT06512883), is recruiting. It is an AstraZeneca Phase 3 open-label basket (estimated n=14; last update 24 August 2026). Cohort 1 is paediatric EGPA; cohort 2 is paediatric HES. One Canadian site is listed as Research Site, Toronto, Ontario, M5G1X8 (status recruiting). ClinicalTrials.gov does not name a PI or a hospital. The postal code matches the Hospital for Sick Children campus; that is not a CT.gov PI listing. Other countries on the registry include the United States, Brazil, France, India, Israel, and Mexico (mix of recruiting and not-yet-recruiting). Ages 6 to <18, weight ≥15 kg. That is a trial population, not the Canadian commercial HES label.

Approval matrix (HES indication)

Weight floors: FDA 12+, no kg floor; Japan 12+, no kg floor (30 mg Q4W; 10 mg syringe not for HES; under-12 not studied); Health Canada 12+ and ≥40 kg if 12–17; EU/UK 12+ and ≥35 kg; Switzerland 12+, no kg floor. Japan (12+, no kg floor) differs from Canada (12+ and ≥40 kg if 12–17) and CLIPS (6–<18, ≥15 kg). Your doctor will follow the label of the country where it is prescribed.

Access by country (HES)

• Canada (adults / labelled adolescents): Specialist can prescribe the labelled use now (12+, and ≥40 kg if 12–17). Public listing for HES not posted. Private insurance / exceptional access. SAP is the wrong route. Connect360 is not written here as HES bridging — the clinic asks Innomar at 1-833-360-2666. Japan and Switzerland are in-country commercial paths there, not a Canadian travel path.
• B. Canada paediatric trial (only Canadian enrolment path for under-12, or 12–17 under 40 kg): Commercial HES is not labelled under 12, or 12–17 under 40 kg. CLIPS NCT06512883 is recruiting at Research Site, Toronto ON M5G1X8. Ages 6 to <18, ≥15 kg; HES is cohort 2. CT.gov facility name is Research Site only. Ask the paediatric haematologist/immunologist to contact that Toronto site, or AZ Clinical Study Information Center 1-877-240-9479 / information.center@astrazeneca.com with NCT06512883. NATRON is active but no longer taking new patients (ages 12+) and is not this trial. Trial dose Q4W; ≥35 vs <35 kg are different trial dose levels — the trial’s 35 kg cut-off is not the Health Canada label’s 40 kg floor for ages 12–17.
• United States: FDA-labelled 13 May 2026. Hematology or allergy/immunology; US prior authorization still applies.
• United Kingdom: HES is on the GB SmPC (12+, ≥35 kg). Ask NHS/specialist commissioning — public funding for this indication not confirmed here.
• EU: The European Commission approved Fasenra for HES on 3 July 2026, as an “add-on treatment”. The EU label covers “adult and adolescent patients aged 12 years and older weighing at least 35 kg”. It applies to HES that is “inadequately controlled” and “without an identifiable non-haematologic secondary cause”. In plain words, you must be 12 or older and weigh at least 35 kg. The 35 kg minimum applies to adults too. It is for HES that is not well controlled on current treatment. It is used together with your other HES medicines. It is not for HES caused by another condition outside the blood. EU approval does not mean Fasenra is sold or publicly funded for HES in every EU country. Each country decides on launch and public funding. NATRON sites (active but no longer taking new patients; ages 12+) do not equal a prescription.
• Australia: Application under evaluation. Not a confirmed ARTG HES listing. Specialist + TGA/compassionate pathways.
• A. Japan in-country commercial: PMDA 18 May 2026. Adults and children 12+; 30 mg SC Q4W; no kg floor. F/P status and active/recurrent disease in the PI related-notes. 10 mg syringe not in this HES variation. Under-12 not studied. This is a Japan in-country path, not a Canadian travel path. This differs from Canada (12+ and ≥40 kg if 12–17) and CLIPS (6–<18, ≥15 kg). PI: https://pins.japic.or.jp/pdf/newPINS/00071595.pdf
• C. Switzerland in-country label: 12+ F/P-negative HES. Authorization 19 May 2026 (Swissmedic Journal 05/2026, Zul. 66582 / Pen 67581, Neue Indikation HES). 30 mg SC Q4W. No kg floor. 21 May 2026 is Compendium news. RMP is not the legal act. Swiss public listing (SL) for HES not confirmed. This is a Switzerland in-country path, not a Canadian travel path.
• If your regulator has not authorized HES: do not import on your own. Plan any travel to a country where it is approved, such as the US, Canada or the EU. Do it only with medical and legal advice from a local specialist. Approval there does not guarantee you can get it or that it is paid for.

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What HES is, in plain language

HES is not one disease. It is a group of rare conditions in which eosinophils — a type of white blood cell — stay too high and damage organs. Skin, lungs, gut, nerves, and heart are commonly involved. People can live with fatigue, rashes, breathing trouble, abdominal pain, or more dangerous organ injury. Diagnosis is often delayed because the symptoms look like allergy, asthma, infection, or vasculitis.

Clinicians group HES by cause, because treatment is not the same for every group:

• Myeloid / neoplastic HES with the FIP1L1::PDGFRA fusion (sometimes written FIP1L1-PDGFRα) is usually treated first with the tyrosine-kinase inhibitor imatinib, not with an IL-5 biologic.
• Lymphocytic HES and idiopathic HES are more often managed with corticosteroids, other immunosuppressants or cytotoxic drugs, and, more recently, biologics that target eosinophils.
• Secondary HES from a drug reaction, parasite, HIV, or a non-blood cancer is treated by removing or treating that cause. Those patients were not the NATRON population and are outside the new Canadian indication.

The Canadian Product Monograph is explicit: because treatment differs by subgroup, genetic testing for FIP1L1-PDGFRα should be completed to guide the choice. That is a conversation to have before anyone starts a biologic.

Canadian how-common-is-this numbers are unknown. Estimates extrapolated from US claims data are not a count of Canadian patients.

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What the new Canadian label actually says

From the Health Canada–authorized Product Monograph (5 August 2026):

Indication. Fasenra is indicated as an add-on to standard therapy for patients aged 12 years and older with hypereosinophilic syndrome without an identifiable non-hematologic secondary cause.

Adolescents. Health Canada authorized pediatric use for HES in patients 12 to <18 years who weigh ≥40 kg, based on limited adolescent data plus extrapolation from adults. It is not indicated under age 12, or under 40 kg in the 12–17 group.

Dose (HES). 30 mg subcutaneously once every 4 weeks — the same every-four-week schedule used in EGPA, not the every-eight-week maintenance schedule used in asthma after the first three doses.

Who starts it. Treatment should be initiated by a qualified clinician experienced in diagnosing and treating severe asthma, EGPA, and HES. After training, a patient or caregiver may inject if the physician agrees, with follow-up.

Do not stop steroids on your own. The label warns against abrupt corticosteroid withdrawal. If a taper is appropriate, it must be gradual and supervised. Steroid reduction can unmask problems the steroids were hiding.

Devices. 30 mg/mL in a 1 mL single-use prefilled syringe or Fasenra Pen autoinjector. Store refrigerated (2–8 °C); may be kept at room temperature up to 25 °C for a maximum of 14 days, then used or discarded. Do not freeze or shake.

Fasenra was already marketed in Canada for other indications (original NOC 22 February 2018; first sale 28 March 2018). The HES text is a new authorized use of an already-sold product, not a brand-new drug arriving from abroad.

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How this differs from Nucala — and from the US label

Versus Nucala (mepolizumab) in Canada. Health Canada authorized Nucala in 2021 as add-on standard therapy for adults with HES for ≥6 months without an identifiable non-hematologic secondary cause (SNDS, NOC 14 September 2021; see Health Canada Regulatory Decision Summary for that submission). Nucala binds IL-5 itself. Fasenra binds the IL-5 receptor alpha on eosinophils and, in laboratory studies, depletes those cells through antibody-dependent cell-mediated cytotoxicity. There is no head-to-head HES trial. Nature Medicine authors note that failing one anti-IL-5/receptor biologic does not always mean a second will fail — that observation comes from retrospective off-label series, not from NATRON.

Versus the FDA label. FDA approved the HES indication effective 13 May 2026 (sBLA 761070/S-023). DailyMed wording: adults and pediatric patients aged 12 years and older with HES without an identifiable non-hematologic secondary cause; 30 mg SC every 4 weeks. The US label does not add the Canadian ≥40 kg adolescent weight floor. The European Commission approved an EU HES indication on 3 July 2026. It is add-on treatment for inadequately controlled HES in people aged 12 and older weighing at least 35 kg — a third wording. Families should use the Canadian monograph with a Canadian prescriber.

Dosing trap. If someone already uses Fasenra for asthma (30 mg every 8 weeks after the loading phase), HES dosing is every 4 weeks. That is a specialist decision, not a patient self-adjustment.

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The evidence: NATRON (NCT04191304)

The Canadian and US labels rest on NATRON, a phase 3, multicentre, randomized, double-blind, placebo-controlled, 24-week trial with an ongoing open-label extension.

Sponsor / ID. AstraZeneca. Protocol D3254C00001. ClinicalTrials.gov: NCT04191304. Published: Ogbogu PU, Roufosse F, Akuthota P, et al. Nat Med. Published 31 March 2026. doi:10.1038/s41591-026-04315-8. A correction was posted 5 May 2026 (doi:10.1038/s41591-026-04425-3).

Research team (as listed on the paper).

• First author / investigator: Princess U. Ogbogu, Division of Pediatric Allergy, Immunology, and Rheumatology, University Hospitals Rainbow Babies and Children’s Hospital, Case Western Reserve University School of Medicine, Cleveland, Ohio.
• Corresponding author: Amy D. Klion, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health, Bethesda, Maryland. NIH intramural support is disclosed.
• Other academic investigators include Florence Roufosse (Université Libre de Bruxelles), Praveen Akuthota (UC San Diego), Paneez Khoury (NIAID), and investigators in Poland, France, Germany, Japan, the UK, the Netherlands, and China.
• Industry authors are AstraZeneca employees (Gaithersburg, Warsaw, Cambridge, Gothenburg).
• Funding: AstraZeneca (Södertälje, Sweden). Medical writing support was industry-funded (disclosed).

Where it ran. 40 sites in 15 countries: Argentina, Austria, Belgium, China, Denmark, France, Germany, India, Israel, Japan, the Netherlands, Poland, South Korea, the UK, and the USA. Canada is not on that list. Enrollment 20 July 2020 to 13 November 2024; last double-blind visit 7 May 2025. The open-label extension is ongoing. ClinicalTrials.gov status: active but no longer taking new patients; estimated study completion 28 February 2027. Ages 12+. Not adult-only. Not “closed.”

Who got in (plain language).

• Age 12 or older with documented HES (persistent eosinophilia >1,500 cells/µL without a secondary cause on two tests at least a month apart, plus organ problems attributed to eosinophils).
• Negative for the FIP1L1::PDGFRA fusion (and other known imatinib-sensitive mutations).
• Stable HES medicines for at least 4 weeks.
• Either flaring at screening or at least two flares in the prior year that needed more treatment.
• Blood eosinophils ≥1,000 cells/µL at screening, and a short steroid “responsiveness” test (counts falling below 1,000 after two days of oral steroid) before randomization.

Who was kept out (high-level). Life-threatening HES as judged by the investigator; confirmed EGPA; systemic mastocytosis; untreated helminth infection; recent serious infection; certain cancers; HIV; prior benralizumab failure. People with FIP1L1::PDGFRA-positive disease were excluded because imatinib is the standard path for that genotype.

What happened. 134 people were randomized; 133 received at least one dose (67 benralizumab 30 mg SC every 4 weeks, 66 placebo), on top of stable background therapy. Median age 51 (range 14–87); 62% female; 75% idiopathic HES; 12% lymphocytic HES; four adolescents (three on drug, one on placebo). About three-quarters were already on oral steroids (median 5 mg prednisone-equivalent).

Primary result. Time to first HES flare. A flare meant clinical or lab worsening that led to an oral-steroid increase of ≥10 mg/day for at least two days, or more/new cytotoxic or immunosuppressive therapy, or hospitalization. Flares occurred in 13/67 (19.4%) on benralizumab versus 28/66 (42.4%) on placebo — a 65% reduction in the risk of first flare (hazard ratio 0.35; 95% CI 0.18–0.69; P=0.0024).

Key secondary results (multiplicity-controlled, all statistically significant):

• Flare or withdrawal: 22.4% vs 45.5% (odds ratio 0.31; P=0.0033) — a 52% relative reduction in the proportion with flare.
• Annualized flare rate: 0.41 vs 1.23 per year (rate ratio 0.34; P=0.0008).
• Time to hematologic relapse (eosinophils ≥1,000 cells/µL): 92% lower hazard (HR 0.08; P<0.0001).
• Fatigue (PROMIS Fatigue 7a) at week 24: least-squares mean difference −4.72 points (P=0.0017), with separation from week 4.

Limitations the paper itself flags. Small sample (rare disease). Only four adolescents. Life-threatening HES was excluded, so this trial does not answer emergency use. Background steroids were not allowed to taper during the 24-week double-blind period, so NATRON does not prove a steroid-sparing effect even though fewer people on drug needed steroid increases. Median time since diagnosis (1.9 years) was shorter than in the registrational mepolizumab HES trial. Long-term durability sits in an unpublished OLE.

Safety in NATRON (double-blind). Any adverse event: 64.2% benralizumab vs 66.7% placebo. Most common on drug: headache (16.4% vs 7.6%). Serious adverse events: 7.5% vs 7.6%; none judged treatment-related. One death on benralizumab (sepsis), not considered related by the investigator. The Canadian monograph’s HES adverse-event table (≥4% and more common than placebo) lists headache (16% vs 8%), influenza-like illness (6% vs 0), abdominal pain (6% vs 3%), nausea, injection-site reactions, back pain, allergic rhinitis, and rash. US DailyMed highlights headache, hypersensitivity reactions, and influenza-like illness as the HES reactions ≥5% and more common than placebo.

Hypersensitivity, including anaphylaxis, is a labelled risk for Fasenra in all indications. Reactions can occur hours or days after injection. Helminth infections should be treated first; if a parasitic infection appears on treatment and does not respond, the drug is stopped until it resolves. The Canadian PM also notes post-marketing Strongyloides reports with insufficient evidence of causation, and suggests screening people at risk.

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Access in Canada: what a patient or caregiver can actually do

1. This is now a labelled, marketed medicine — SAP is not the usual route

Health Canada’s Special Access Program is for drugs not marketed in Canada. Fasenra has been sold here since 2018. For HES, the usual path is: specialist prescription of a now-labelled product, then a fight over payment. SAP is generally the wrong form.

If a clinician still talks about SAP, ask them to confirm they mean a different, unmarketed product — not Fasenra.

2. Who should you see

Ask your family doctor or existing specialist for referral to a clinician who manages HES or complex eosinophilic disease. That is typically:

• a hematologist (especially if a myeloid variant or FIP1L1::PDGFRA testing is in play),
• an allergist-immunologist, or
• a respirologist or internal medicine specialist with eosinophilic-disease experience.

Academic centres in large cities (for example Toronto teaching hospitals) are the usual starting point; there is no verified national HES centre directory The Canadian Organization for Rare Disorders (CORD; raredisorders.ca) is an advocacy network, not a clinic.

Bring: eosinophil counts over time, biopsy or imaging of affected organs, current steroid and immunosuppressant doses, flare history, and any genetic results (FIP1L1::PDGFRA / PDGFRA, and other kinase testing if done). If that genetic test has not been done, ask why.

3. Script for the visit

You can say:

Health Canada has authorized Fasenra as add-on therapy for HES in people 12 and older without a non-hematologic secondary cause. I would like you to confirm my HES subtype, including FIP1L1-PDGFRα testing, and tell me whether I fit the labelled population. If I do, can you prescribe it, and what is the realistic funding path — private insurance, a provincial exceptional-access request, NIHB, or a manufacturer program? I understand an NOC is not public coverage. I also do not want to stop prednisone without a written taper plan.

Ask, specifically:

• Do I have a non-hematologic secondary cause that would put me outside the indication?
• Am I FIP1L1::PDGFRA-positive (imatinib first) or negative (biologic discussion)?
• If I am already on Nucala, is a switch evidence-based for me, or would you add or stay?
• HES dose is every 4 weeks — who injects, where, and how is anaphylaxis monitoring handled for the first doses?
• Adolescents: do they weigh ≥40 kg? (Canadian commercial label.)
• If under 12, or 12–17 and under 40 kg: commercial HES is not labelled. Ask about CLIPS NCT06512883 (Toronto Research Site, M5G1X8) — ages 6 to <18, ≥15 kg, HES cohort 2. NATRON is active but no longer taking new patients (ages 12+) and is not that trial.

4. Public coverage: assume “not yet” unless your plan says otherwise

• CDA-AMC: Completed Fasenra reviews are SR0561 (severe eosinophilic asthma, 21 August 2018) and a request-for-advice on the same indication. SR0962-000 (EGPA) is status Received, submitted 20 August 2026. No HES reimbursement review was listed as of 2 September 2026. Provincial plans have not been handed a HES recommendation they can copy.
• Ontario EAP: Fasenra is an Exceptional Access Program product, not an ODB Formulary limited-use benefit. Posted EAP criteria (updated 12 April 2021) are severe eosinophilic asthma in adults only. No HES criteria are posted. A specialist can still submit a standard EAP request for an unlisted indication; that is case-by-case, not a right, and asthma criteria will not automatically cover HES. HES dosing is 30 mg every 4 weeks (13 doses/year), not the asthma maintenance schedule of every 8 weeks after loading.
• Ontario published price (same DINs, asthma EAP listing): Drug Benefit Price under the table heading Effective date: April 28, 2023 on the ministry EAP product-prices page (page updated 31 August 2026; the adjacent March 31, 2023 block does not list Fasenra): Fasenra PFS (DIN 02473232) $4,115.54 and Fasenra Pen (DIN 02496135) $4,036.80 per 30 mg dose. Manufacturer list price for the HES indication was not posted. These unit prices are the asthma-listed EAP DBP for the same DINs. Multiplying them out to a yearly figure does not give an HES public cost (HES is Q4W; asthma maintenance is Q8W after loading). HES is not a posted EAP indication.
• Quebec / INESSS: Public listing identified is severe eosinophilic asthma in adults. An HES listing was not found.
• Atlantic provinces / NIHB / remaining plans: HES listing was not read for this article. Treat as unknown, not as “not listed.” The asthma Limited Use / EAP criteria do not apply to this indication.

NOC ≠ public funding. Repeat it to anyone who says “it’s approved, so it’s covered.”

5. Private insurance and the manufacturer program

If you have private drug benefits, ask the specialist’s office to submit a prior authorization using the HES indication and NATRON/label language, not the asthma indication. Insurers often default to the old criteria.

AstraZeneca Canada’s Fasenra patient support program is Connect360° (Innomar):

• Phone: 1-833-360-2666, Monday–Friday 8 a.m.–8 p.m. ET
• Email: connect360@innomar-strategies.com
• Enrolment is through a healthcare provider. The consumer site is for people already prescribed Fasenra.

Connect360 is not written here as bridging for HES. The clinic asks Innomar at 1-833-360-2666 (Monday–Friday, 8 a.m.–8 p.m. ET) or connect360@innomar-strategies.com. Enrolment is through a prescriber. Manufacturer programs are not a public right and can change.

6. Clinical trials

NATRON (NCT04191304) status: active but no longer taking new patients (results posted; estimated completion 28 February 2027). Ages 12+. Not adult-only. Not “closed.” There is no Canadian NATRON site. NATRON is not CLIPS. CLIPS NCT06512883 is the separate 6–<18 recruiting path (Research Site, Toronto M5G1X8; n=14 worldwide).

CLIPS (NCT06512883) is recruiting for children. AstraZeneca sponsor; estimated n=14; last update 24 August 2026. Open-label Phase 3 basket: cohort 1 paediatric EGPA; cohort 2 paediatric HES. Canadian listing: Research Site, Toronto, Ontario, M5G1X8 (recruiting). CT.gov names the facility “Research Site” only.

Who it is for (plain language, HES cohort): age 6 to <18; weight ≥15 kg; documented HES (persistent eosinophilia >1,500/µL without secondary cause on two tests ≥1 month apart, plus eosinophil-mediated organ involvement); symptomatic, prior flare, or investigator-judged severity; AEC ≥1,000/µL at screening; FIP1L1-PDGFR negative. Not for life-threatening HES, HE-US (hypereosinophilia of unknown significance), or systemic mastocytosis. Prior benralizumab in an interventional study is an exclusion.

Dose in the trial: benralizumab SC Q4W. Participants ≥35 kg and <35 kg get different trial dose levels. This is not the same as the Canadian commercial HES label (12+ and ≥40 kg if 12–17).

How to ask: Commercial HES is not labelled under 12, or 12–17 under 40 kg. Ask the paediatric haematologist or immunologist to contact the Toronto CLIPS site, or the AZ Clinical Study Information Center 1-877-240-9479 / information.center@astrazeneca.com with NCT06512883.

7. If the answer is “not a candidate”

People with FIP1L1::PDGFRA-positive disease, secondary (non-hematologic) eosinophilia, EGPA rather than HES, age under 12, or life-threatening complications excluded from NATRON need a different plan. Nucala remains the other labelled Canadian HES biologic for adults (with its own ≥6-month wording). Public funding for Nucala in HES was also not confirmed in a dedicated CDA-AMC HES recommendation found for this article — another “authorized ≠ funded” file. That is the Canadian pattern, not a unique Fasenra problem.

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Safety the household should watch for

Seek urgent care for swelling of face, mouth or tongue, trouble breathing, fainting, hives, or a widespread rash after an injection — even days later.

Do not stop oral or inhaled steroids because a biologic was started.

Tell the clinic about travel to parasite-endemic regions, pregnancy, breastfeeding, live vaccines, or a history of reaction to monoclonal antibodies. Pregnancy data are insufficient; the Canadian PM says Fasenra should not be used in pregnancy unless the expected benefit justifies fetal risk, and to contact a physician if pregnancy occurs on treatment or within four months after stopping.

Adolescents: only four were in NATRON. The Canadian label still authorized 12+ / ≥40 kg on limited data plus adult extrapolation. That uncertainty belongs in the consent conversation.

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Bottom line

Fasenra is labelled for HES in the United States (FDA, 13 May 2026, age 12+, no kg floor), Canada (Health Canada, 5 August 2026, age 12+ and ≥40 kg if 12–17), Japan (PMDA, 18 May 2026, age 12+, 30 mg SC Q4W, no kg floor), the United Kingdom (GB SmPC, age 12+ and ≥35 kg), and Switzerland (Swissmedic Journal 05/2026, legal act 19 May 2026, age 12+, no kg floor). The European Union (EU) has approved it too (European Commission, 3 July 2026, age 12+ and ≥35 kg). EU approval does not mean it is sold or funded in every EU country. Australia remains under evaluation. Your doctor will follow the label of the country where it is prescribed. The weight floors differ by country.

Canada is covered separately; it is not the main focus. NATRON (NCT04191304) cut the risk of a first flare by 65% versus placebo in FIP1L1::PDGFRA-negative disease; it has no Canadian sites and is active but no longer taking new patients (ages 12+). For children, CLIPS NCT06512883 is recruiting at Research Site, Toronto ON M5G1X8 (ages 6 to <18, ≥15 kg; HES is cohort 2). That is the Canadian enrolment path for under-12, or 12–17 under 40 kg — not the commercial label.

Authorized is not funded. A specialist can prescribe where the drug is labelled. Public listing, NHS commissioning, Swiss SL/LIM, and provincial/territorial coverage are separate fights. Ask the clinician who treats HES to confirm the subtype, write the prescription if you fit that country’s label, and start the paperwork the same week — not after someone tells you “it’s approved, so you’re fine.”

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Primary sources

1. AstraZeneca Canada Inc. FASENRA / FASENRA PEN (benralizumab) Product Monograph. Date of Authorization: 2026-08-05. Control number 301480. https://www.astrazeneca.ca/content/dam/az-ca/downloads/productinformation/fasenra-product-monograph-en.pdf
2. Health Canada Drug Product Database. Details for FASENRA, DIN 02473232, monograph date 2026-08-05. https://health-products.canada.ca/dpd-bdpp/info?code=96262&lang=eng
3. Health Canada Drug and Health Products Portal. Details for FASENRA. https://dhpp.hpfb-dgpsa.ca/dhpp/resource/96262
4. US FDA. BLA 761070/S-023 corrected supplement approval letter. Effective action date 2026-05-13. https://www.accessdata.fda.gov/drugsatfda_docs/appletter/2026/761070Orig1s023correctedltr.pdf
5. DailyMed. FASENRA (benralizumab) injection. Updated 13 May 2026. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=da6aca1a-19ed-44a4-abb7-696c7d58b784
6. ClinicalTrials.gov. NCT04191304. A Phase III Study to Evaluate the Efficacy and Safety of Benralizumab in Patients With Hypereosinophilic Syndrome (HES) (NATRON). https://clinicaltrials.gov/study/NCT04191304
7. Ogbogu PU, Roufosse F, Akuthota P, et al. Benralizumab versus placebo for hypereosinophilic syndrome: a randomized, placebo-controlled phase 3 trial. Nat Med. Published 31 March 2026. doi:10.1038/s41591-026-04315-8
8. Health Canada. Regulatory Decision Summary for Nucala (mepolizumab) HES SNDS. https://dhpp.hpfb-dgpsa.ca/review-documents/resource/RDS00861
9. Canada’s Drug Agency (CDA-AMC). benralizumab (Fasenra) reimbursement review SR0561 (severe eosinophilic asthma). https://www.cda-amc.ca/benralizumab
10. Health Canada. Request a drug through the Special Access Program. https://www.canada.ca/en/health-canada/services/drugs-health-products/special-access/drugs.html
11. European Commission. Implementing Decision C(2026) 4819 final, 3 July 2026, adding the HES indication to the EU marketing authorisation. Union Register: https://ec.europa.eu/health/documents/community-register/html/h1252.htm. European Medicines Agency. Fasenra EPAR and current product information: https://www.ema.europa.eu/en/medicines/human/EPAR/fasenra. Earlier opinion on variation, 21 May 2026: https://www.ema.europa.eu/en/medicines/human/variation/fasenra
12. Ontario Ministry of Health. Exceptional Access Program product prices (Fasenra DINs 02473232 / 02496135, DBP effective 2023-04-28; page updated 2026-08-31). https://www.ontario.ca/page/exceptional-access-program-product-prices
13. Ontario RxCoverage / EAP criteria for Fasenra (asthma only, updated 2021-04-12). https://www.on.rxcoverage.ca/products/details/11244
14. CDA-AMC find-reports: benralizumab (SR0561 asthma complete; SR0962-000 EGPA received 2026-08-20; no HES file). https://www.cda-amc.ca/find-reports?search_api_fulltext=benralizumab
15. AstraZeneca Canada. Connect360° support. Bridging asterisk: eligible patients, evaluated on enrollment form. https://www.fasenra.ca/en/resource-hub/patient/support.html
16. Swissmedic RMP summary, Fasenra (benralizumab), document date 19 May 2026 — same calendar day as the Journal legal act (Zul. 66582 / Pen 67581), not a denial of Zulassung. https://www.swissmedic.ch/dam/swissmedic/en/dokumente/marktueberwachung/rmp/benralizumab_fasenra_rmp-summary.pdf.download.pdf/Benralizumab_Fasenra_RMP%20Summary.pdf
17. Swissmedic Journal 05/2026, Zul. 66582 / Pen 67581, Neue Indikation HES. Legal act 19 May 2026. 21 May 2026 is Compendium news, not the authorization. RMP is not the legal act.
18. compendium.ch news 29067, Fasenra HES indication extension, 21 May 2026; Fachinformation Stand 03/2026.
19. PMDA. 承認品目一覧. 2026.5.18: ファセンラ皮下注30 mgシリンジ/ペン, 好酸球増多症候群, 希少疾病用医薬品. https://www.pmda.go.jp/files/000281577.pdf
20. ClinicalTrials.gov. NCT06512883 — CLIPS. https://clinicaltrials.gov/study/NCT06512883
21. Fasenra Japanese package insert (PI), 2026年5月改訂 第5版. §6 12+, 30 mg SC Q4W; §9.7.3 12歳未満は未実施. https://pins.japic.or.jp/pdf/newPINS/00071595.pdf
22. PMDA review report. https://www.pmda.go.jp/drugs/2026/P20260528001/670227000_23000AMX00016_A100_1.pdf
23. PMDA book search (same PI). https://www.pmda.go.jp/PmdaSearch/bookSearch/01/04987650680010

Company newswire (AstraZeneca Canada / CNW, 10 August 2026) was used only as a date clue and was not treated as proof of authorization.