Bluebird Bio said Tuesday that he suspended clinical trials involving his gene therapy for sickle cell disease after receiving reports that two patients treated with the single therapy were diagnosed with cancer.
The tests were put on “temporary suspension” so that Bluebird could investigate the cancer cases to determine whether they were caused by the redesigned HIV virus used to administer its gene therapy. That link has not yet been established, the company said.
In December 2018, Bluebird released the diagnosis of myelodysplastic syndrome (MDS), a disease similar to bone marrow cancer, in a patient with sickle cell disease who had undergone treatment with his Lentiglobin gene therapy three years earlier. At that time, Bluebird concluded that the chemotherapy administered to the patient to prepare for gene therapy was probably the cause of the cancer, based on tests he performed. The patient later died last July.
advertising
The new cancer cases, however, will redirect attention to a possible cancer risk inherent in Bluebird gene therapy – and also raise concerns for any gene therapy company that uses redesigned lentiviruses as part of its treatments.
Bluebird’s shares fell 32% to $ 31 in Tuesday’s trading – its lowest price in seven years.
advertising
Bluebird said it received a report last week that a patient with sickle cell disease treated for more than five years with Lentiglobin gene therapy was diagnosed with acute myeloid leukemia.
Also last week, Bluebird said it learned that a second patient with sickle cell disease, also treated with Lentiglobin, had been diagnosed with myelodysplastic syndrome.
“The safety of every patient who has participated in our studies or is treated with our gene therapies is a top priority for us,” said Bluebird CEO Nick Leschly in a statement. “We are committed to fully assessing these cases in partnership with healthcare providers who support our clinical studies and appropriate regulatory agencies. Our thoughts are with these patients and their families during this period. “
The Food and Drug Administration and the European Medicines Agency have been informed of cancer cases and the suspension of clinical trials, Bluebird said. The investigation of cancer cases will seek to determine whether Lentiglobin gene therapy could have caused cancer in patients, possibly by inserting the modified stem cells in the wrong place. This is a theoretical risk for any gene therapy that uses viruses as a delivery vehicle, but has not yet materialized in clinical trials until Bluebird reports.
Before patients can be treated with gene therapy for sickle cell disease or other blood-related diseases, they must first receive chemotherapy called busulfan, which cleans – or “conditions” – the bone marrow so that it can accept the conditions. healthy cells delivered by gene therapy.
Cases of MDS have been previously reported in patients undergoing conditioning of stem cell transplantation with busulfan. Clinical trials are underway looking to develop more effective and safer ways to prepare patients for gene therapy. The research is important because, even if genetic therapies for sickle cell disease or related genetic diseases are approved, patients may be reluctant to try them for fear that the cure may also put them at a greater risk of developing cancer later.
There have been no cases of AML or SMD reported in patients with beta thalassemia treated with Zynteglo, the Bluebird gene therapy approved in Europe that is done similarly to Lentiglobin. However, the company has temporarily suspended the marketing of Zynteglo while the investigation of cancer cases is ongoing.