NEW YORK (Reuters Health) – New results for Bluebird Bio Inc.’s LentiGlobin treatment for beta thalassemia continue to look promising.
A pair of phase 1-2 studies reported in the April 19 New England Journal of Medicine say treatments of 22 volunteers with transfusion-dependent disease reduced or eliminated the need for long-term red-cell transfusions in every case without any serious adverse events.
Transfusions were discontinued in 15 patients with the inherited condition. In the remaining patients, the need for transfusion was reduced by nearly 70%, chief author Dr. Alexis Thompson of the Ann and Robert H. Lurie Children’s Hospital of Chicago told Reuters Health in a telephone interview.
“These were individuals receiving large amounts of blood annually,” she said. “For individuals who want to consider a curative therapy, who do not have a sibling donor (who can give them healthy stem cells), gene therapy may hold promise for them in terms of achieving transfusion independence.”
“The data are of great significance and impact,” said Alessandra Biffi, director of the Gene Therapy Program at Dana Farber / Boston Children’s Cancer and Blood Disorders Center, who was not involved in the research.
“This kind of approach could provide a valuable treatment opportunity for patients, particularly those lacking a family donor,” Dr. Biffi said. “As always, long term follow up data will be instrumental for confirming the persistence and long term safety of this very promising approach.”
The treatment has moved into phase 3 testing, said Dr. Thompson.
Atlanta-based Bluebird financed the study. The treatment, which involves inserting a functional human beta-globin gene into the patient’s stem cells and returning those cells to the patient, was given a breakthrough-therapy designation in 2015 thanks to earlier results on fewer patients.
Mutations in the beta thalassemia gene – and more than 200 are known to occur – lower levels of hemoglobin in the blood, causing weakness, fatigue and other serious complications. Most require lifelong red-cell transfusions, which carry their own risks.
The patients in the studies, designated HGB-204 and HGB-205, were age 5 to 35. People with advanced organ damage were excluded. Only one dose of the therapy was given in the two open-label studies.
All initially received conditioning treatment with intravenous busulfan to destroy their defective cells and most of the serious side effects appear to be related to that aspect of the treatment. None were ascribed to LentiGlobin therapy.
After a follow-up period that ranged from 15 to 42 months, three of the nine patients with the beta zero form of the condition no longer needed transfusions and the rest required significantly fewer transfusions.
Among the 13 people with the non-beta zero form, 12 became transfusion independent.
Peak hemoglobin typically occurred within nine to 12 months after infusion.
There is no evidence so far that the treatment wears off, “but the evidence is limited,” cautioned Dr. Thompson, who is head of hematology and director of the Comprehensive Thalassemia Program at Lurie.
The patients will be followed for an additional 15 years.
If approved, cost of the therapy could be a major issue. “But a lifetime of transfusions and chelation is also very expensive,” said Dr. Thompson. “If you have an effective one-time therapy in a young person, the savings would be considerable.”
SOURCE: https://bit.ly/2qEhx4g and https://bit.ly/2HNIZEZ
N Engl J Med 2018.
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