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ThalassemiaMarch 2017Summary reviewed June 2026

What the HGB-205 Trial Found — Gene Therapy for Sickle Cell Disease

Researchers tested a gene therapy that adds a modified gene to a patient's own blood stem cells. Fifteen months after treatment, the patient had no sickle cell crises and the therapy gene made up about half of their hemoglobin.

What the trial was testing

The HGB-205 enrolled 7 patients with thalassemia. The study was sponsored by Genetix Biotherapeutics Inc. and tracked outcomes across the full group of patients who matched the trial's eligibility profile.

It was an early-stage trial — researchers are still confirming safety and getting an early look at how well the treatment works. Trials at this stage are designed to produce evidence regulators and physicians can act on — not just observations to follow up later.

What the results showed

The patient had no sickle cell crises for 15 months after gene therapy treatment.

The New England journal of medicine · 2017 · NCT02151526

These findings — that the new gene made up half the patient's hemoglobin and stopped sickle cell crises — were published in the The New England journal of medicine and represent the headline result of the study.

Researchers tracked outcomes across 7 patients enrolled in the trial. The result was consistent enough across the group that the team felt confident reporting it.

What this means for patients

For patients with thalassemia, this result changes the calculus on what to ask their care team about. Whether it changes day-to-day care depends on factors like disease subtype, prior treatments, and where the patient is in their care journey.

What you can do now

This was an early-stage study testing gene therapy in one patient with sickle cell disease. The treatment showed promise but was not yet FDA-approved at the time. A related gene therapy called Lyfgenia is now FDA-approved for sickle cell disease. Ask your doctor about approved gene therapies and whether you might be eligible.

Eligibility for the treatments mentioned above depends on specific test results and clinical history. Bring this summary, the trial name, and your most recent labs or pathology report to your next visit.