exagamglogene autotemcel for transfusion-dependent beta-thalassaemia

• exagamglogene autotemcel (exa-cel; Casgevy) is a novel, single-dose, ex vivo CRISPR/Cas9 gene-edited autologous stem cell therapy
• recommended by NICE under a Managed Access Agreement (MAA) via the Innovative Medicines Fund (IMF) as an option for treating transfusion-dependent beta-thalassaemia (TDT) in individuals aged 5 years and older
• indicated for patients for whom haematopoietic stem cell transplantation (HSCT) is clinically appropriate, but a human leukocyte antigen (HLA)-matched related stem cell donor is not available

Mechanism of Action and Technology

• autologous CD34+ haematopoietic stem and progenitor cells (HSPCs) are harvested from the patient and edited ex vivo using non-viral CRISPR/Cas9 technology
• targeted gene editing disrupts the erythroid-specific enhancer region of the BCL11A gene, which normally represses gamma-globin production after birth
• disruption of BCL11A reactivates gamma-globin expression, leading to the production of functional fetal haemoglobin (HbF)
• increased intracellular HbF combines with alpha-globin to replace deficient adult beta-globin, correcting ineffective erythropoiesis and eliminating the clinical requirement for red blood cell (RBC) transfusions

Clinical Pathway and Administration

• stem cell harvest: CD34+ HSPCs are collected via apheresis using standard mobilization protocols
• ex vivo manufacturing: harvested cells undergo CRISPR/Cas9 editing at a centralized facility and are cryopreserved
• myeloablative conditioning: patients receive high-dose busulfan conditioning to clear bone marrow niches prior to cell infusion
• infusion and engraftment: exa-cel is administered as a single intravenous infusion, requiring inpatient isolation until successful neutrophil and platelet engraftment

Primary Care Role and Post-Treatment Monitoring

• referral and identification: consider referral or discussion with a regional Specialist Haemoglobinopathy Centre for TDT patients aged 5 years or older who lack an HLA-matched sibling donor
• transfusion independence: clinical trials demonstrate sustained transfusion independence (>90% of evaluable patients), removing the requirement for ongoing RBC transfusions and iron chelation
• organ iron-overload surveillance: exa-cel halts further iron accumulation, but pre-existing iron-induced organ damage (e.g., cardiac failure, liver disease, diabetes, hypogonadism, osteoporosis) requires ongoing primary care monitoring and specialist oversight
• conditioning-related risks: high-dose myeloablative busulfan carries a significant risk of infertility and primary ovarian failure; fertility preservation must be arranged prior to conditioning
• post-transplant infection risk: monitor for late post-transplant infectious complications and ensure revaccination in alignment with specialist tertiary care protocols

Clinical Evidence Summary

• primary trial data (CLIMB-THAL-111): over 90% of evaluable patients maintained weighted average haemoglobin >= 9.0 g/dL without RBC transfusions for at least 12 consecutive months
• haemoglobin recovery: total haemoglobin levels increased to >= 11.0 g/dL by month 3 and >= 12.0 g/dL by month 6, driven by durable, pancellular HbF expression
• quality of life: statistically significant improvements were reported across validated patient-reported outcomes (EQ-5D, FACT-G, BMTS)

Reference:

1. National Institute for Health and Care Excellence (NICE). Exagamglogene autotemcel for treating transfusion-dependent beta-thalassaemia in people 5 years and over. NICE Technology Appraisal Guidance [TA1003]. Published September 2024; updated October 2026.
2. Locatelli F, Lang P, Corbacioglu S, et al. Transfusion independence after exagamglogene autotemcel in patients with transfusion-dependent beta-thalassemia. HemaSphere. 2023;7(S3):S270.