Rare Disease Report

bluebird bio Showcase Their Preliminary Gene Therapy Data For Beta-Thalassemia Major

JUNE 15, 2014
James Radke

This morning, the executive team at bluebird bio held a conference call announcing the preliminary results from their phase I/II study involving gene therapy to treat patients with beta-thalassemia major.  The data was presented at 19th Annual Congress of the European Hematology Association (EHA) in Milan, Italy by Marina Cavazzana, M.D on June 14th, in her oral presentation entitled “Improving gene therapy for beta-thalassemia major: initial results from Study HGB-205”.
Beta-thalassemia major is a rare hereditary blood disorder caused by a genetic abnormality of the beta globin gene resulting in defective red blood cells. It affects approximately 15,000 people in the United States and Europe. Treatment for patients with beta-thalassemia major include chronic transfusion therapy, iron chelation, splenectomy,  allogeneic hematopoietic transplantation, and/or supportive measures.
The gene therapy being tested is the lentiviral vector BB305 in the HGB-205 clinical study being conducted in France (there is another clinical study also being conducted in the United States but data is not available yet). 
At  the EHA meeting, preliminary data from two patients who received the gene therapy were announced, and after 4.5 months and 2 months post gene therapy, both subjects remain blood transfusion independent and their hemoglobin levels were approaching normal levels (At 4.5 months following autologous transplant subject 1 had a total hemoglobin of 10.1 g/dL of which 6.6 g/dL was therapeutic betaAT87Q-globin, and at 2 months post-transplant subject 2 had a total hemoglobin of 11.6 g/dL of which 4.2 g/dL was betaAT87Q-globin). 
Equally important, no drug related adverse events have been reported in either patient.
The HGB-205 study in Europe plans to enroll a total of 7 patients and will follow them for 24 months.
A second study based in the United States (“Northstar study”) plans to enroll 15 patients and will also follow them for 24 months.
It should also be noted that an earlier phase 1/2 study with another lentiviral vector (HPV569) was also presented at the EHA meeting and in that study, one patient was shown to be infusion free for upto 72 months. However, another patient did not respond as well to the gene therapy and the company is currently focused on the newer BB305 lentiviral vector.
Based on the preliminary data now available, bluebird bio concluded:          
  • BB305 lentiviral vector and improved manufacturing process produce superior transduction efficiency as compared with HPV569
  • With BB305 lentiviral vector in Study 2, neither subject has received a transfusion since the second week post transplantation
    • Production of βA-T87Q-globin has been rapid and clinically significant resulting in near-normal hemoglobin levels
  • Initial safety profile is consistent with autologous transplantation, without gene-therapy related adverse events, and with polyclonal reconstitution in the first subject
  • These data demonstrate that early transfusion independence (within weeks of transplantation) with near-normal levels of hemoglobin can be achieved with ex-vivo gene therapy using BB305 lentiviral vector in subjects with β0/βE -thalassemia major
Image of preliminary results from HGB-205 produced by bluebird bio and available at the company's investor page

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