**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.

⭐ 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.

⭐ 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.

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).

Severe Asthma with Fungal Sensitisation (SAFS)

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

Aspergillus Bronchitis

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

⭐ Summary Table

Condition Approx UK Patients Rare Disease?
CPA ~3,600 ✔ YES
ABPA 125,000–250,000 ✘ NO
SAFS ~8,000 ✔ YES
Aspergillus Bronchitis <10,000 ✔ YES

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

⭐ 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.

⭐ 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.

⭐ 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.

⭐ 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.

⭐ 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.

⭐ 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.

⭐ 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.

⭐ 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.

⭐ 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.

by GAtherton