Gene Therapy in SCD & Thalassemia 🧬🩸
1️⃣ Goal:
Fix the genetic defect causing SCD (HbS) or β-thalassemia (β-globin mutation)
➤ Either correct the gene OR reactivate HbF
#GeneTherapy #SCD #TDT
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2️⃣ Key Platforms:
🔹 Lentiviral Vector Gene Addition
🔹 CRISPR-Cas9 Gene Editing
#CASGEVY #ZYNTEGLO
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3️⃣ CASGEVY™ (exa-cel)
➤ CRISPR-Cas9 edits BCL11A enhancer in autologous HSCs → ↑HbF
➤ Approved: US, EU, UK for SCD & TDT
➤ Curative in most patients
Ref: Frangoul H, N Engl J Med 2021
#CRISPR #HbF
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4️⃣ ZYNTEGLO® (beti-cel)
➤ LentiGlobin BB305: β-globin gene insertion into HSCs
➤ For TDT, especially non-β⁰/β⁰
➤ 90% transfusion independence
Ref: Thompson AA, N Engl J Med 2018
#Thalassemia #LentiGlobin
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5️⃣ Eligibility
➤ Age 12
➤ No active infections
➤ No advanced organ damage
➤ ECOG 0–2
➤ HSCT not feasible or no matched donor
#PatientSelection #HSCTAlternative
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6️⃣ Procedure Steps
1.HSC collection
2.Ex vivo gene editing or transduction
3.Myeloablative conditioning (Busulfan)
4.Reinfusion
5.Engraftment & monitoring
#GeneTherapySteps
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7️⃣ Efficacy
CASGEVY:
➤ ~94% SCD free of VOCs at 12 mo
➤ ~88% TDT transfusion independent
ZYNTEGLO:
➤ ~90% transfusion-free
[Ref: NEJM 2021; NCT03655678, NCT03745287]
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8️⃣ Safety Concerns
➤ Busulfan-related toxicity
➤ Insertional mutagenesis (lentiviral)
➤ Long-term cancer risk under surveillance
#SafetyFirst #Myeloablation
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9️⃣ Cost & Access
➤ CASGEVY: ~$2.2M USD
➤ ZYNTEGLO: ~$2.8M USD
➤ High upfront, but potentially curative
➤ Global access remains limited
#Pharma #Equity #ValueBased
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🔟 Future Directions
➤ Non-genotoxic conditioning
➤ In vivo editing
➤ Expanded eligibility (peds, comorbidities)
#FutureOfTherapy
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Conclusion
Gene therapy is transformational in SCD & TDT
➤ Curative for many
➤ Requires specialized centers
➤ Safety & equity still major priorities
#Hematology #SickleCell #Thalassemia #GeneTherapy #CRISPR