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Gene Therapy Provides Hope for Patients with Hemophilia

A majority of patients with hemophilia B avoided joint bleeds after receiving gene therapy.
Published Online: Dec 13,2017
Laurie Toich, Assistant Editor
Researchers recently reported positive findings from a phase 1/2 clinical trial investigating gene therapy in patients with hemophilia B, according to a study published by the New England Journal of Medicine.

The study showed that patients were able to produce stable levels of a clotting factor following a single infusion of the gene therapy.

“A one-time therapy sufficient to prevent bleeding without further medical intervention is the ideal treatment goal for patients with hemophilia,” said lead investigator Lindsey A. George, MD. “This cohort of 10 patients all safely experienced sustained clinical benefit after 1 infusion.”

The authors also reported that patients were able to stop prophylactic therapy with infusions of manufactured clotting factors.

Patients with hemophilia B have low levels of clotting factor IX due to a genetic mutation. Since these patients are unable to clot, bleeding events can be life-threatening.

“People who live with hemophilia face a lifelong need for vigilant monitoring and recurrent factor concentrate infusions to prevent spontaneous, potentially life-threatening bleeds and to protect their joints,” said senior author Katherine High, MD. “The discipline required to execute the usual prophylactic regimen can exact a heavy toll on quality of life that most people take for granted, and those regimens result in significant costs to patients, families and the health care system.”

Included in the study were 10 male patients with hemophilia B. The researchers used Factor IX-Padua (FIX-Padua), which is 8 to 10 times stronger than a normal factor, according to the study. For hemophilia gene therapy, the researchers delivered a corrective gene to the patient in order to increase therapeutic levels of the clotting factor.

The authors said that preclinical animal studies showed that the gene therapy cured the disease; however, previous human trials resulted in an immune response due to high doses of the clotting factor. In the new trial, the authors used FIX-Padua to take advantage of its potency.

The authors discovered that patients achieved factor levels of 33%, which lessened their disease severity and mitigated bleeding events, according to the study.

Patients were able to avoid experiencing painful joint bleeds, which previously occurred when clotting levels dropped due to fluctuations after traditional treatment, according to the study.

These positive results were sustained for up to 78 weeks, according to the authors.

Notably, none of the patients experienced serious adverse events. The authors found that 8 patients did not require additional factor treatments and 9 did not experience bleeds after receiving the gene therapy, according to the study. One patient who had to be treated with the factor had significant joint damage, but they required 91% less factor after the gene therapy compared with baseline.

These results suggest that the gene therapy could be effective for patients with hemophilia, but additional studies are needed.

“We look forward to continuing the development of this therapy in a Phase 3 trial,” Dr George said. “I am optimistic this study is just the beginning of a true paradigm shift in the treatment of hemophilia.”