Long-Term Data for bluebird bio’s betibeglogene autotemcel (beti-cel) Gene Therapy Show Patients Across Ages and β-thalassemia Genotypes Achieve Transfusion Independence and Remain Free from Transfusions Up to Six Years Presented at 62nd ASH Meeting - Seite 3

Long-term follow-up study LTF-303: Safety

In LTF-303, there were no deaths, no graft-versus-host disease (GVHD), and no cases of replication-competent lentivirus, insertional oncogenesis or clonal dominance were observed. No drug-related adverse events (AEs) were reported >2 years post-infusion. Serious AEs during LTF-303 unrelated to beti-cel included gonadotropic insufficiency, ectopic pregnancy, gall bladder wall thickening/polyp, bacteremia, neutropenia and major depression (n=1 for each).

Phase 3 Pediatric Patients: Efficacy

As of March 3, 2020, 24 pediatric patients (<12 years: n=13; ≥12 to <18 years: n=11) were treated and had a median follow-up of 15.5 months (min-max: 1.1 – 29.5 months) in Phase 3 HGB-207 (Northstar-2) and HGB-212 (Northstar-3) studies.

In these Phase 3 studies, the median age at which the children under 12 received their first transfusion was 11 months of age; for the adolescents between the ages of 12 and 18, the median was eight months of age.

Following treatment with beti-cel, 87% (13/15) of evaluable patients under the age of 18 years, including four patients under age 12, achieved TI. As of March 3, 2020, these patients continue to be free of transfusions for a median duration of 14.9 months (min-max: 12.2 – 21.6 months), with median weighted average total Hb levels of 11.3 g/dL (min-max: 9.4 – 12.8 g/dL).

Phase 3 Pediatric Patients: Safety

Drug-related AEs in pediatric patients during the HGB-207 and HGB-212 trials were non-serious and included tachycardia (Grade 1, n=1) and abdominal pain (Grade 1, n=2) on the day of infusion, and Grade 3 thrombocytopenia in one patient post-infusion. There were no deaths, no GVHD, no graft failures, and no cases of replication-competent lentivirus, insertional oncogenesis or clonal dominance were observed.

Post-infusion non-hematologic Grade ≥3 AEs in ≥3 patients < 18 years of age (N=24) included stomatitis (n=14), febrile neutropenia (n=12), decreased appetite (n=5), epistaxis (n=4), alanine aminotransferase increase (n=3), hypoxia (n=3) and pyrexia (n=3).

The presentations are now available on demand on the ASH conference website:

• Oral #153: Long-Term Efficacy and Safety of Betibeglogene Autotemcel Gene Therapy for the Treatment of Transfusion-Dependent β-Thalassemia: Results in Patients with up to 6 Years of Follow-up
• Oral #154: Favorable Outcomes in Pediatric Patients in the Phase 3 HGB-207 (Northstar-2) and HGB-212 (Northstar-3) Studies of betibeglogene autotemcel Gene Therapy for the Treatment of Transfusion-dependent β-thalassemia
• Poster #776: Improvement in Erythropoiesis Following Treatment with Betibeglogene Autotemcel Gene Therapy in Patients with Transfusion-Dependent β-Thalassemia in the Phase 3 HGB-207 Study
• Poster #1699: Response of Patients with Transfusion-dependent β-thalassemia (TDT) to betibeglogene autotemcel (beti-cel; LentiGlobin for β-thalassemia) Gene Therapy Based on HBB Genotype and Disease Genetic Modifiers

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