**Understanding Medicines in Rare Forms of Aspergillosis:

A Complete Guide for Patients with CPA, ABPA, SAFS and Aspergillus Bronchitis**

People living with chronic or allergic forms of aspergillosis often face treatments that fall outside the standard medicine licensing system. You may hear terms like off-label, unlicensed, specials medicines, or rare disease. This guide explains these concepts clearly and safely in a way that helps you feel informed and confident in your care.

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⭐ 1. What is a rare disease?

In the UK and EU, a rare disease is defined as:

A condition affecting fewer than 1 in 2,000 people
(≈ fewer than ~33,500 people in the UK)

Although each rare disease affects relatively few people, over 7,000 rare diseases exist, so collectively they affect 1 in 17 people.

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⭐ 2. Are CPA, ABPA, SAFS and Aspergillus Bronchitis rare diseases?

Here is how the main Aspergillus-related conditions compare to the rare-disease definition.

Chronic Pulmonary Aspergillosis (CPA)

• ~3,600 diagnosed UK patients (under-diagnosis likely, but still rare).
  ✔ CPA is officially recognised as a rare disease.

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Allergic Bronchopulmonary Aspergillosis (ABPA)

• Occurs in 2.5–5% of all people with asthma.

• UK estimate: 125,000–250,000 patients.
  ✘ ABPA is NOT a rare disease (but it is under-recognised).

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Severe Asthma with Fungal Sensitisation (SAFS)

• ~8,000 estimated UK cases.
  ✔ SAFS meets the definition of a rare disease.

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Aspergillus Bronchitis

• Likely <10,000 UK patients.
  ✔ Aspergillus Bronchitis qualifies as a rare disease.

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⭐ Summary Table

Understanding whether a condition is rare helps explain why some treatments fall outside standard licensing.

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⭐ 3. What is “off-label” prescribing?

Every medicine has a licence describing:

• the condition it treats

• dose

• age group

• how long it can be used

• route (tablet, injection, inhaler)

Off-label means a doctor uses a licensed medicine in a way not included in the licence.

This can mean:

• different disease

• different dose

• different age group

• different route

• different duration

Off-label prescribing is safe, legal, common and essential, especially in rare diseases.

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⭐ 4. What is an “unlicensed” medicine?

An unlicensed medicine is one that has no UK licence at all.

Examples:

• a medicine made specially for one patient (“specials”)

• a liquid formulation when only tablets are sold

• imported medicines licensed in another country

• alternatives for patients with drug allergies

Unlicensed does not mean unsafe — it means the medicine isn’t commercially licensed in the UK.

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⭐ 5. Why are off-label and unlicensed medicines common in rare diseases?

Rare diseases like CPA, SAFS and Aspergillus bronchitis:

• affect small patient numbers

• often have no licensed treatment

• rely on specialist expertise and experience

• require individualised dosing

• cannot wait for slow or expensive licensing processes

Without off-label and unlicensed medicines, many rare-disease patients would have no treatment options.

This is why specialist centres exist.

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⭐ 6. Biologics for ABPA: NOT licensed, but safe and widely used

This is a key point for patients.

❗ No biologic is licensed for ABPA

(as of 2025)

Not licensed for ABPA:

• Omalizumab (Xolair)

• Mepolizumab (Nucala)

• Benralizumab (Fasenra)

• Dupilumab (Dupixent)

All biologics used in ABPA are therefore off-label.

⭐ Why do specialists use them anyway?

Because evidence is strong that biologics:

• reduce ABPA flare-ups

• reduce steroid need

• improve lung function

• improve symptoms

• control eosinophilic/IgE-driven inflammation

• reduce hospital admissions

ABPA lacks a commercially licensed biologic
→ but specialist evidence supports them strongly.

This is high-quality off-label prescribing.

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⭐ 7. How do doctors decide what evidence is “good enough”?

Doctors use several acceptable forms of evidence, including:

✔ Randomised controlled trials

✔ National/international guidelines

✔ NAC / BTS / ECCMID / IDSA specialist protocols

✔ Observational studies and real-world evidence

✔ Case series and case reports

✔ Pharmacological reasoning (mechanisms of disease)

✔ MDT (multidisciplinary team) agreement

✔ Expert clinical experience (important in rare diseases)

All of these count as legitimate evidence.

Rare-disease medicine relies on the best available evidence, not only the “highest-level” evidence.

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⭐ 8. Who holds responsibility if something goes wrong?

The prescriber carries responsibility, even for:

• off-label use

• unlicensed medicines

• imported medicines

• specials items

They must:

• justify the decision

• explain risks and benefits

• obtain consent

• document

• monitor

If they follow guidance, they are fully protected by:

• NHS indemnity

• GMC standards

• Trust governance

Patients are not responsible for adverse outcomes.

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⭐ 9. Is this risky for the doctor?

Only if done unsafely.

When the doctor:

✔ follows specialist guidelines
✔ explains the situation
✔ documents their reasoning
✔ uses MDT support
✔ monitors closely

…the risk is minimal and fully protected.

In rare diseases, NOT prescribing off-label can be riskier if it denies a patient effective treatment.

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⭐ 10. How are patients protected?

Patients with CPA, ABPA, SAFS or Aspergillus bronchitis are protected by:

• careful MDT assessment

• specialist supervision

• decades of centre experience

• guideline-supported decisions

• regular reviews and monitoring

• clear communication and consent

• NHS governance systems

Your care is safe, structured and evidence-based.

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⭐ Final reassurance for Aspergillosis patients

If you have CPA, ABPA, SAFS or Aspergillus bronchitis:

• You are not receiving “experimental” treatment.

• Off-label or unlicensed medicines are normal, safe, and essential.

• Your specialist team carries the responsibility for these decisions.

• Biologics for ABPA are off-label because licensing is slow — not because they are untested.

• You are protected by national standards, MDTs, and specialist expertise.

• Your treatment is based on the best available evidence, even when the condition is rare.

This is expert, modern care designed to give you the best possible outcome.

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by GAtherton