99.5% reduction in annualized rate of vaso-occlusive crises (VOC) and acute chest syndrome (ACS) in Group C patients with a history of VOCs and ACS (n=14) who had at least six months follow-up
At up to 24 months, no reports of serious VOC or ACS in Group C patients (n=18) with at least six months follow-up
Group C patients with at least six months follow-up continue to produce consistent levels of gene therapy-derived anti-sickling hemoglobin (HbAT87Q) at up to 24 months, reducing levels of abnormal sickle hemoglobin (HbS)
Key markers of hemolysis approach near-normal levels in Group C patients, supporting the potential of LentiGlobin for SCD to modify the underlying pathophysiology of the disease
“Vaso-occlusive crises (VOCs) are the painful, life-threatening episodes that are the primary clinical manifestation of sickle cell disease. The nearly complete elimination of VOCs that we saw in this study is impressive and demonstrates the potential of LentiGlobin for SCD as a treatment for this serious disease,” said
SCD is a serious, progressive and debilitating genetic disease caused by a mutation in the β-globin gene that leads to the production of abnormal sickle hemoglobin (HbS). HbS causes red blood cells to become sickled and fragile, resulting in chronic hemolytic anemia, vasculopathy and unpredictable, painful VOCs. For adults and children living with SCD, this means painful crises and other life altering or life-threatening acute complications—such as ACS, stroke and infections. If patients survive the acute complications, vasculopathy and end-organ damage, resulting complications can lead to pulmonary hypertension, renal failure and early death; in the
“As a physician treating sickle cell for over 10 years, the excruciating pain crises that my patients suffer from is one of the most challenging and frustrating aspects of this disease,” said presenting study author
LentiGlobin for SCD was designed to add functional copies of a modified form of the β-globin gene (βA-T87Q-globin gene) into a patient’s own hematopoietic (blood) stem cells (HSCs). Once patients have the βA-T87Q-globin gene, their red blood cells can produce anti-sickling hemoglobin, HbAT87Q, that decreases the proportion of HbS, with the goal of reducing sickled red blood cells, hemolysis and other complications.
HGB-206: Group C Updated Efficacy Results
In Group C of HGB-206, 25 patients were treated with LentiGlobin for SCD and have up to 24.8 months of follow-up (median of 12.1; min.-max.: 2.8—24.8 months). Results from Group C are as of
In 16 patients with six or more months of follow-up, median levels of gene therapy-derived anti-sickling hemoglobin, HbAT87Q, were maintained with HbAT87Q contributing at least 40% of total hemoglobin. At last visit reported, total hemoglobin ranged from 9.6 – 16.2 g/dL and HbAT87Q levels ranged from 2.7 – 9.4 g/dL. At Month 6 the production of HbAT87Q was associated with a reduction in the proportion of HbS in total hemoglobin. Patients had a median of ≤ 60% HbS. All patients in Group C were able to stop regular blood transfusions and remain off transfusions at three months post-treatment.
There was a 99.5% mean reduction in annualized rate of VOC and ACS among the 14 patients who had at least six months of follow-up and a history of VOCs or ACS, defined as four or more VOC or ACS events in the two years prior to treatment. These 14 patients had a median of eight events in the two years prior to treatment (min.-max.: 4 – 28 events).
There were no reports of serious VOCs or ACS at up to 24 months post-treatment in patients with at least six months of follow-up (n=18). As previously reported, one non-serious Grade 2 VOC was observed in a patient approximately 3.5 months post-treatment with LentiGlobin for SCD.
In sickle cell disease, red blood cells become sickled and fragile, rupturing more easily than healthy red blood cells. The breakdown of red blood cells is hemolysis and this process occurs normally in the body. However, in sickle cell disease hemolysis happens too quickly due to the fragility of the red blood cells, which results in hemolytic anemia.
Patients treated with LentiGlobin for SCD demonstrated improvement in key markers of hemolysis, which are indicators of the health of red blood cells. Lab results assessing these indicators were available for the majority of the 18 patients with 6 months of follow-up. The medians for reticulocyte counts (n=15), lactate dehydrogenase (LDH) levels (n=13) and total bilirubin (n=16) improved compared to screening and stabilized by Month 6. In patients with Month 24 data (n=5) these values approached the upper limit of normal by Month 24. These results suggest treatment with LentiGlobin for SCD is improving biological markers of sickle cell disease.
Assays were developed by bluebird bio to enable the detection of HbAT87Q and HbS protein in individual red blood cells as well as to assess if HbAT87Q was pancellular, present throughout all of a patient’s red blood cells. Samples from a subset of patients in Group C were assessed. In nine patients who had at least six months of follow-up, the average proportion of red blood cells positive for HbAT87Q was greater than 70%, and on average more than 85% of red blood cells contained HbAT87Q at 18 months post-treatment, suggesting near-complete pancellularity of HbAT87Q distribution.
HGB-206: Group C Safety Results
One patient with a history of frequent pre-treatment VOE, pulmonary and systemic hypertension, venous thrombosis, obesity, sleep apnea and asthma had complete resolution of VOEs following treatment, but suffered sudden death 20 months after treatment with LentiGlobin for SCD. The patient’s autopsy revealed cardiac enlargement and fibrosis, and concluded the cause of death was cardiovascular, with contributions from SCD and asthma. The treating physician and an independent monitoring committee agreed this death was unlikely related to LentiGlobin for SCD gene therapy.
The presentation is now available on demand on the EHA25 website:
- Abstract #S282: “Outcomes in patients treated with LentiGlobin for sickle cell disease (SCD) gene therapy: Updated results from the Phase 1/2 HGB-206 group C study”
HGB-206 is an ongoing, Phase 1/2 open-label study designed to evaluate the efficacy and safety of LentiGlobin gene therapy for SCD that includes three treatment cohorts: Groups A (n=7), B (n=2) and C (n=25). A refined manufacturing process that was designed to increase vector copy number (VCN) and improve engraftment potential of gene-modified stem cells was used for Group C. Group C patients also received LentiGlobin for SCD made from HSCs collected from peripheral blood after mobilization with plerixafor, rather than via bone marrow harvest, which was used in Groups A and B of HGB-206.
LentiGlobin for Sickle Cell Disease Regulatory Status
bluebird bio reached general agreement with the
bluebird bio anticipates additional guidance from the FDA regarding the commercial manufacturing process, including suspension lentiviral vector. bluebird bio announced in a
About LentiGlobin for Sickle Cell Disease
LentiGlobin for sickle cell disease is an investigational gene therapy being studied as a potential treatment for SCD. bluebird bio’s clinical development program for LentiGlobin for SCD includes the ongoing Phase 1/2 HGB-206 study and the ongoing Phase 3 HGB-210 study.
LentiGlobin for SCD received orphan medicinal product designation from the
LentiGlobin for SCD is investigational and has not been approved in any geography.
bluebird bio is conducting a long-term safety and efficacy follow-up study (LTF-303) for people who have participated in bluebird bio-sponsored clinical studies of betibeglogene autotemcel for β-thalassemia or LentiGlobin for SCD. For more information visit: https://www.bluebirdbio.com/our-science/clinical-trials or clinicaltrials.gov and use identifier NCT02633943 for LTF-303.
About bluebird bio, Inc.
bluebird bio is pioneering gene therapy with purpose. From our
bluebird bio is a human company powered by human stories. We’re putting our care and expertise to work across a spectrum of disorders, including cerebral adrenoleukodystrophy, sickle cell disease, β-thalassemia and multiple myeloma, using three gene therapy technologies: gene addition; cell therapy and (megaTAL-enabled) gene editing.
bluebird bio has additional nests in
LentiGlobin and bluebird bio are trademarks of bluebird bio, Inc.
bluebird bio Forward-Looking Statements
This release contains “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995, including statements regarding the company’s development and regulatory plans for the LentiGlobin for SCD product candidate, and the company’s intentions regarding the timing for providing further updates on the development of the product candidate. Any forward-looking statements are based on management’s current expectations of future events and are subject to a number of risks and uncertainties that could cause actual results to differ materially and adversely from those set forth in or implied by such forward-looking statements. These risks and uncertainties include, but are not limited to: the risk that the COVID-19 pandemic and resulting impact on our operations and healthcare systems will affect the execution of our development plans or the conduct of our clinical studies; the risk that even if LentiGlobin for SCD addresses ACS and VOC events, that it may not address progressive organ damage experienced by patients with SCD; the risk that the efficacy and safety results observed in the patients treated in our prior and ongoing clinical trials of LentiGlobin for SCD may not persist or be durable; the risk that the efficacy and safety results from our prior and ongoing clinical trials will not continue or be repeated in when treating additional patients in our ongoing or planned clinical trials; the risk that the HGB-206 and HGB-210 clinical studies as currently contemplated may be insufficient to support regulatory submissions or marketing approval in the
Source: bluebird bio, Inc.