bluebird bio has presented new data for its gene therapy betibeglogene autotemcel (beti-cel) at the European Hematology Association 2021 virtual congress (EHA) in transfusion dependent beta thalassemia (TDT).
The new data includes a total of 63 paediatric, adolescent and adult TDT patients treated with beti-cel (marketed as Zynteglo in the UK and EU) – 19 of these patients have at least five years of follow-up, eight with at least six years and two with up to seven years of follow-up.
The patients are enrolled across the phase 1/2 HGB-204 (Northstar) and HGB-205 studies, as well as the phase 3 HGB-207 (Northstar-2) and HGB-212 (Northstar-3) studies.
As of 9 March 2021, 51 of 63 beti-cel-treat patients across a range of age groups, genotypes and TDT severity had completed two years of follow-up in their parent study and were enrolled into a 13-year long-term follow-up study – LTF-303.
Of the 51 patients enrolled in the long-term study, 40 patients achieved transfusion independence (TI), representing 68% of patients treated in phase 1/2 and 86% of patients treated in phase 3.
In addition, all patients who achieved TI also remained free from transfusions through their last follow-up, with phase 1/2 patients having a median duration TI of 57.1 months and phase 3 patients having a median ongoing TI duration of 26.3 months.
Data from the phase 3 Northstar-2 and Northstar-3 studies also showed that, following treatment with beti-cel, 89% of evaluable patients across ages and genotypes achieved TI as of the data cut-off of 9 March 2021.
These patients have also continued to be free from transfusions for a median duration of 25 months, with median weighted average total haemoglobin levels during TI of 11.6 g/dL.
According to exploratory analyses, biomarkers of ineffective erythropoiesis also trended toward normal over time in beti-cel-treated patients who achieved TI.
In a statement, bluebird said this supports the disease-modifying potential of beti-cel in patients living with TDT.
The biotech company added that grade ≥3 veno-occlusive liver disease observed in three study patients was attributed to busulfan conditioning and resolved with defibrotide treatment.
Of the 27 paediatric patients treated in the phase 3 studies, 91% of evaluable patients under the age 18 years also achieved TI.
“TDT is usually diagnosed in the first two years of life, and patients with this disease will require regular blood transfusions for the rest of their lives – most as often as every few weeks,” said Richard Colvin, VP, interim chief medical officer of bluebird bio.
“It is truly transformative for these patients and their families that they no longer need ongoing blood transfusions,” he added.