ASH Report: Long-Term Follow-Up Analysis of bluebird bio Gene Therapy

December 6, 2020 – Patients with transfusion-dependent beta thalassemia who were treated in bluebird bio’s clinical trials with beti-cel (LentiGlobin) gene therapy have shown sustained efficacy for up to six years in follow-up analysis. These findings were presented by Dr. Janet Kwiatkowski of the Children’s Hospital of Philadelphia at the 2020 American Society of Hematology (ASH) annual meeting.

32 patients who were treated with beti-cel are currently enrolled in a long-term follow-up study (called LTF-303) to assess the long-term efficacy and safety of the treatment. 22 patients enrolled in the long-term follow-up study had participated in Phase 1/2 studies of beti-cel, while 10 of the patients had participated in Phase 3 studies of beti-cel.

Transfusion independence is defined as maintaining a weighted average hemoglobin ≥9 g/dL in the absence of red blood cell transfusions for at least 1 year. 64% of patients who participated in the Phase 1/2 trials of beti-cel achieved transfusion independence, with a weighted average hemoglobin of 10.4 g/dL. The Phase 3 studies of beti-cel utilized a refined manufacturing process, which enabled 90% of patients to achieve transfusion independence, with a weighted average hemoglobin of 12.5 g/dL.

All patients were taking iron chelation prior to beti-cel infusion, but following treatment, only 26/32 (81%) patients restarted iron chelation therapy. Of these, 11 have since discontinued chelation. Phlebotomy was used for iron removal in 7/32 patients (22%). Liver Iron Concentration (LIC) in patients who achieved transfusion-independence decreased – especially in patients with elevated baseline LIC. Patients who achieved transfusion-independence experienced a median reduction in LIC of 38% at 2 years.

No adverse events related to beti-cel gene therapy were reported more than 2 years following treatment: no deaths or insertional oncogenesis have been observed, suggesting a favorable long-term safety profile for beti-cel gene therapy.

Further information about the long-term follow-up of beti-cel in transfusion-dependent beta thalassemia can be found in the ASH meeting abstract at:

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