What eosinophil count is needed for Fasenra?

Fasenra may be an option for severe asthma if you have an eosinophil count of at least 150-300 cells per microliter (cells/μL), determined from a common blood test, plus you have required an oral corticosteroid treatment (like prednisone) at least twice per year, despite maximum inhalation therapy.

A blood eosinophil count of 150 cells/μL or more may help to identify eosinophilic asthma, although clinical guidelines do not provide an exact number.

Tell your doctor if you experience 2 or more asthma attacks each year that require oral corticosteroid treatment despite using maximum doses of inhaled corticosteroids and long-acting beta² agonists (ICS/LABA).

Examples of oral corticosteroids include medicines like prednisone or methylprednisolone. If you've been using a steroid medication, do not stop using it unless your doctor tells you to.

Characteristics of severe asthma include:

• Taking a high-dose ICS/LABA.
• Experienced 2 asthma attacks in the last year, each requiring oral steroid treatment (for at least 3 days).
• Asthma symptoms disrupt your sleep.
• Limiting activities because of asthma symptoms.
• FEV1: ≤75% of expected. FEV1 is a lung function test used to help diagnose asthma or other lung disorders.

What are eosinophils?

Eosinophils are a type of white blood cell found in the immune system that normally help fight disease and infections. Eosinophils may lead to swelling (inflammation) in the lungs that may cause severe asthma attacks known as eosinophilic asthma.

Eosinophils have been found to be elevated in some patients with severe asthma. It is considered a biomarker that may help your healthcare provider determine which treatment might work best for you. Your doctor can determine your eosinophil count using a standard laboratory blood test called a complete blood count (CBC).

Eosinophil counts can change naturally during the day and may be affected by corticosteroid use.

What is Fasenra approved to treat?

Fasenra (benralizumab) is a prescription biologic medicine used with other asthma treatments to treat severe eosinophilic asthma in people 6 years of age and older. Fasenra works by targeting and removing eosinophils, one cause of severe asthma.

Fasenra is classified as an interleukin-5 (IL-5) receptor inhibitor, a monoclonal antibody. It works by binding directly to the IL-5α receptor on eosinophils. Natural killer (NK) cells then induce cell death and reduce the number of eosinophils in the blood.

Fasenra is not approved for treatment of other eosinophilic conditions and is not a rescue medication for sudden breathing problems. Do not stop taking your other asthma medicines unless your healthcare provider tells you to.

Other biologics used in the treatment of eosinophilic asthma include:

• dupilumab (brand name: Dupixent)
• mepolizumab (brand name: Nucala)
• reslizumab (brand name: Cinqair)

Studies with Fasenra and eosinophil count

SIROCCO and CALIMA

The the 48-week long Phase 3 SIROCCO study and the 56-week long CALIMA study in 2,510 patients, investigators looked at the use of Fasenra in patients with severe asthma compared to a placebo (an inactive agent).

Researchers were looking to see the rate of asthma exacerbations in patients with baseline blood eosinophil counts of greater than or equal to 300 cells/μL, and who were taking high-dose inhaled steroids and long-acting beta² agonists.

Patients were split into groups based on their geography, age, and blood eosinophil count (≥300 cells/μL or <300 cells/μL). The mean baseline eosinophil count was 472 cells/μL in both studies.

Fasenra was administered once every 4 weeks for the first 3 doses, and then every 4 or 8 weeks thereafter as add-on to background treatment, and was evaluated compared to placebo.

In the treatment period, 35% of patients (in SIROCCO) and 40% of patients (in CALIMA) receiving Fasenra experienced an asthma exacerbation compared to 51% on placebo, a significant finding.

Patients with a baseline blood eosinophil count of at least 300 cells/μL and with a history of 3 or more exacerbations within the 12 months prior to the study showed a numerically greater response than those with counts less than 300 cells/μL. However, reductions in exacerbation rates were observed irrespective of baseline peripheral eosinophil counts.

In these studies, following the injection of Fasenra at the recommended dose, blood eosinophils were reduced to a median absolute blood eosinophil count of 0 cells/μL. This level of reduction was seen at the first time point (at 4 weeks of treatment), and was maintained throughout the treatment period.

In a Phase 2 study, a reduction in blood eosinophil counts was observed 24 hours after receiving a dose of Fasenra.

Related questions

• What are monoclonal antibodies?
• Does Fasenra weaken your immune system?
• How long does Fasenra take to work?

ZONDA

Another study showed patients receiving Fasenra compared to a placebo achieved greater reductions in daily maintenance oral corticosteroid dose, while maintaining asthma control.

The Phase 3 study (ZONDA) evaluated Fasenra compared to placebo in adults with asthma using medium or high doses of ICS/LABA inhalers and on continuous oral corticosteroid treatment for at least 6 months. Patients also had an eosinophil count of at least 150 cells/μL, at least one asthma attack in the last year and FEV1 <80% predicted.

The baseline median oral corticosteroid dose was 10 mg (range: 8 to 40 mg) for all groups.

Results showed that Fasenra led to a 75% reduction in the dose of the oral corticosteroid vs. a 25% reduction in the placebo group, a clinically significant effect. A reduction in exacerbation rates of 55% to 70% (compared to placebo) was also demonstrated.

How do I know if I have eosinophilic asthma?

Your healthcare provider can measure your eosinophil count with a simple blood test to help determine if your asthma is of the eosinophilic type. Other criteria, such as the severity of your asthma, the medicines you currently use, and your need for oral corticosteroids are also taken into consideration to determine your eligibility for Fasenra treatment.

Studies have shown that about 30% to 50% of people with severe uncontrolled asthma have eosinophilic asthma. In primary care settings, eosinophilic asthma is diagnosed by having a number of eosinophils of at least 150 to 300 cells/μL.

To have your asthma evaluated, make an appointment with your healthcare provider. Your doctor may want to know how your asthma affects you now, if you had asthma as a child, or if you have specific asthma triggers like pollen or dander. They may review your medications and breathing tests, how often you use rescue inhalers and order any laboratory tests that you might need.

Your healthcare provider may have you fill out a questionnaire, such as the Asthma Control Questionnaire ACQ) or the Asthma Control Test (ACT) to further help determine the severity of your symptoms.

Tell your doctor if you have any of these symptoms, which may mean that your asthma is not fully controlled:

• Asthma symptoms like shortness of breath, chest tightness, cough during the day more than twice per week.
• Nighttime symptoms that wake you up more than twice per month.
• Using a fast-acting (“rescue”) inhaler for symptoms more than twice per week.
• You avoid or skip activities due to your asthma or possible symptoms.
• You use oral corticosteroids for treatment of symptoms. Excessive use of oral corticosteroids can lead to serious side effects, like osteoporosis or type 2 diabetes.

One study suggests that 4 out of 5 adults with severe asthma may have eosinophilic asthma.

How do I use Fasenra for asthma?

Fasenra is given as a subcutaneous (under the skin) injection once every 4 weeks for the first 3 doses, and then once every 8 weeks thereafter. Your doctor will tell you what dose to take.

• It comes as an autoinjector pen (for self injection) or as a syringe (for use by a healthcare provider.) Injections are usually in the thigh or stomach area (abdomen).
• Initially, your doctor will administer it. You or a caregiver may be able to give this medicine at home after training using the pen.
• In people aged 6 to 11 years, Fasenra injection should only be given by a caregiver or healthcare provider.

Side effects

Common side effects that occurred in clinical studies with Fasenra included headache, sore throat, fever and allergic (hypersensitivity) reactions.

Serious side effects can include allergic (hypersensitivity) reactions, including anaphylaxis, which can be fatal. Angioedema (swelling) and urticaria (itching) also occurred. Allergic reactions can sometimes happen hours or even days after your dose.

Tell your healthcare provider or get emergency help right away (call 911 in the U.S) if you have any of the following symptoms of an allergic reaction:

• swelling of your face, mouth and tongue
• breathing problems
• fainting
• dizziness
• feeling lightheaded (low blood pressure)
• rash
• hives / itching

Learn more: Fasenra warnings, precaution and side effects (in more detail)

This is not all the information you need to know about Fasenra (benralizumab) for safe and effective use and does not take the place of your doctor’s directions. Review the full product information and discuss this information and any questions you have with your doctor or other health care provider.