(Reuters Health) – Experimental gene therapy designed to restore production of factor IX has left all 10 hemophiliac volunteers without the need for baseline prophylaxis and halted nearly all excess bleeding, according to a December 6 online report of a small phase 1-2a study in The New England Journal of Medicine.
The one-time infusion uses a bioengineered adeno-associated virus known as SPK-9001 to deliver genetic instructions into liver cells, restoring the body’s ability produce sufficient factor IX.
The treatment is being developed by Spark Therapeutics and Pfizer. Eleven of the 28 authors are Spark employees.
The 10 volunteers, all adult men with hemophilia B, originally had factor IX coagulant activity of 2% or less. With the therapy, levels rose to an average of 33.7% (range, 14% to 81%) with “the near elimination of bleeding and factor use,” said a team led by Dr. Lindsey George of the division of hematology at the Children’s Hospital of Philadelphia.
The average annualized bleeding rate declined significantly from 11.1 events per person per year before treatment to 0.4 events per person year. Nine of the 10 volunteers had no bleeding incidents. Eight of the 10 did not use any factor at all.
Follow-up ranged from 28 to 78 weeks.
The researchers estimated that as a result of the treatments, US$3.6 million worth of factor IX concentrate did not have to be bought.
The treatment did produce elevated liver-enzyme levels in two men, but the levels dropped with short-term glucocorticoid therapy.
In one patient, factor IX activity started to drop over time, from 48% to 30% on day 56, where it stalled with prednisone therapy. When the prednisone was stopped, activity declined to 18% on day 62, where it stayed as prednisone treatment continued.
SOURCES: http://bit.ly/2BBIAky and http://bit.ly/2j06IK4
N Engl J Med 2017.
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