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Abdul Mannan: Why AML inv(16) Isn’t Just “Favourable”

Dr Abdul Mannan/LinkedIn

Dec 1, 2025, 15:22

Abdul Mannan: Why AML inv(16) Isn’t Just “Favourable”

Dr Abdul Mannan, Consultant Haematologist at Betsi Cadwaladr University Health Board, posted on LinkedIn:

“The ‘Harlequin’ Leukemia: Why AML inv(16) Isn’t Just ‘Favourable’

AML with inv(16)(p13.1q22) is one of the most visually striking and biologically distinct subtypes we see. Textbooks call it ‘favourable.’ Clinicians know it’s more complicated.

1. Morphology: The Harlequin Clue

The FAB M4Eo marrow gives it away.
Those eosinophils with mixed orange and purple granules are almost diagnostic.
And if the blasts show CD2 positivity, you already know what the karyotype is likely to say.

2. The Engine: CBFB::MYH11

The fusion traps RUNX1 in the cytoplasm, freezing maturation and driving the disease. Classic CBF biology.

3. The ELN 2022 Twist: KIT Isn’t a Deal-Breaker

About one-third carry KIT mutations, especially D816V.
Yes, relapse risk climbs.
But ELN 2022 keeps CBF-AML in the favourable group regardless because overall survival remains excellent.

Practical point:

Not a transplant trigger in CR1, but absolutely a reason for closer molecular surveillance.

4. Treatment: Do It Properly or Don’t Call It Favourable

Induction:
- CD33-high disease → add Gemtuzumab Ozogamicin where possible.
Consolidation:
- No shortcuts.
- This subtype demands high-dose Cytarabine (HiDAC). Standard-dose consolidation is simply not enough.

5. MRD: Your Early Warning System

Monitor the CBFB::MYH11 transcript every 3 months for two years.
A rising log value means molecular relapse long before counts crash.

Bottom Line

inv(16) isn’t “easy AML.”
It’s highly curable only when treated with precision: recognise the morphology, respect the molecular modifiers, use GO in induction, and commit to HiDAC consolidation.

How are you using Gemtuzumab in your CBF-AML pathways? And what’s your approach to KIT-mutated cases in CR1? Happy to hear how others are tackling this.”

Abdul Mannan