The European Medicines Agency has launched a safety review of bluebird bio’s thalassaemia drug Zynteglo, a conditionally licensed gene therapy in Europe.
Saftey review of Zynteglo is live.
The European Medicines Agency (EMA) has launched a safety review of bluebird bio’s thalassaemia drug Zynteglo, a conditionally licensed gene therapy in Europe.
This review comes after researchers identified an acute myeloid leukaemia (AML) case in a patient who received bb1111 (LentiGlobin), an investigational gene therapy for sickle cell disease (SCD), in a Phase I/II study. This therapy relies on the same viral vector found in Zynteglo which delivers a gene into cells.
Just last month, the U.S. Food and Drug Administration (FDA) also placed a clinical hold on bluebird bio’s LentiGlobin gene therapy trials after two patients with SCD developed AML and myelodysplastic syndrome (MDS). The clinical hold swiftly followed the company’s previously placed voluntary pause on its Phase I/II and III trials.
Currently, Zynteglo is only available from two European centers, and only one patient has so far received the drug outside of a clinical trial setting. Patients who have received either Zynteglo or LentiGlobin are encouraged to contact their physician if they have concerns regarding their treatment.
bluebird bio has said in a recent statement that the suspected unexpected serious adverse reaction “is very unlikely” related to the BB305 lentiviral vector shared between the two therapies.
“In addition to our earlier findings of several well-known genetic mutations and gross chromosomal abnormalities commonly observed in AML in this patient, our latest analyses identified the integration site for the vector within a gene called VAMP4,” bluebird bio’s chief scientific officer Philip Gregory said in a statement. “VAMP4 has no known association with the development of AML nor with processes such as cellular proliferation or genome stability. Moreover, we see no significant gene misregulation attributable to the insertion event.”
Gregory added that the overall data from the studies of Zynteglo offer “important evidence demonstrating that it is very unlikely our BB305 lentiviral vector played a role in this case and we have shared with the FDA that we believe these results support lifting the clinical holds on our β-thalassemia and sickle cell disease programs.”
The statement made by bluebird bio indicates that the patient who developed AML “had significant chromosomal abnormalities and mutations in genes typically associated with the development of AML,” according to laboratory analyses. While the BB305 lentiviral vector was detected in the AML blast cells, researchers suggest the information available was not sufficient to identify causality.
In addition to the single AML case, the company said two other patients who received LentiGlobin also developed MDS, another blood disorder, with one patient experiencing progression to leukemia.
According to the EMA, no leukemia cases have been identified in patients who have received only Zynteglo. The agency indicates that this type of treatment may possibly increase the risk or “cause” a blood cancer, which was recognized when the drug was originally authorized. Patients who take this drug, however, undergo long-term follow-up monitoring in a registry to identify cancer cases.
Given the concerns, bluebird bio has paused the supply of Zynteglo while the EMA examines the evidence to see if the cancer could be associated with their treatment. The agency’s safety committee will examine the evidence in tandem with experts from EMA’s Committee for Advanced Therapies (CAT) to determine next regulatory action steps it needs to take for Zynteglo.
