Gene therapy company bluebird bio (NASDAQ:BLUE) gave an update on the clinical trial of its treatment for sickle cell disease (SCD) showing that patients in the study have remained free of the most serious symptoms of the disease. The results suggest that Bluebird is on track to submit the treatment to the Food and Drug Administration for accelerated approval by next year.

The report provided updated results from the 25 patients in group C of the study designated HGB-206 given LentiGlobin, a which treats the genetic disease by adding functional copies of a gene into the patient's stem cells, thus enabling them to generate red blood cells capable of producing normal anti-sickling hemoglobin, resulting in a lower proportion of sickled cells.

Sickle-shaped red bloods cells in a blood vessel.

Image source: Getty Images.

The results from the ongoing study continue to show that the treatment almost completely eliminates the most serious manifestation of the disease, vaso-occlusive crises (VOCs), which are painful and life-threatening episodes. Patients in the trial experienced a 99.5% reduction in the annualized rate of VOCs and acute chest syndrome (ACS), which is characterized by cough, chest pain, and low oxygen levels.

An earlier report on this trial in December showcased a marked improvement in VOCs and ACS in patients after they had undergone the company's gene therapy. After those results, Bluebird worked with the FDA to change the primary endpoint of the trial to be the elimination of VOCs as opposed to improvement in hemoglobin measurements, clearing the way for accelerated approval if the patients remained free of the events. The results reported Friday seem to support that outcome, with the company anticipating submitting the drug for FDA approval in the blood disorder in the second half of 2021.