Bluebird Starting New Trial in Harder-to-Treat Blood Patients

  • Therapy helped cut transfusion needs for tougher patient group
  • People with disorder can't produce oxygen-carrying molecule

Bluebird Bio Inc. will start an additional trial of its therapy to treat an inherited blood disorder, splitting testing between a genetic subset of patients who have responded best to the treatment and another group for whom it hasn’t been as effective.

The biotechnology company also said Saturday that while the therapy hadn’t ended the need for blood transfusions in the hard-to-treat subset, it had lessened the volume of transfusion needed -- showing the therapy may help them.

Bluebird is testing the therapy, called LentiGlobin BB305, in a trial of 13 patients with beta-thalassemia major. The disorder hampers production of an oxygen-carrying blood molecule called beta-globin, leaving untreated patients anemic and weak, and in need of blood transfusions to get new working red blood cells.

In results presented Saturday, Bluebird released more data on a subgroup of four of the patients, who have a genetic variation called beta-zero beta-zero that leaves them unable to make any of the oxygen-carrying molecule. On Nov. 5, the company said three of the patients hadn’t responded as well to the drug as patients without the variation, which sent Bluebird’s shares down 22 percent on investor concerns about how effective the treatment was.

Reduced Transfusions

Bluebird said Saturday that the beta-zero beta-zero group was able to reduce the volume of transfusions they needed after getting the therapy, ranging from 33 percent less to not needing any transfusions so far, meaning that the drug may help them.

Because beta-zero beta-zeroes cannot make any beta-globin at all, treating them “is perhaps the highest clinical hurdle,” Chief Executive Officer Nick Leschly said last month.

Data from the company-funded study was released at the American Society of Hematology’s annual meeting in Orlando, Florida.

The company will start a separate trial for similar hard-to-treat patients, and keep testing the therapy in patients without the variation. Five patients without the genetic variation and who can make a limited amount of the oxygen transporting molecule haven’t needed transfusions for as long as 7.1 to 16.4 months after therapy.

Leschly said on Dec. 1 that the company is considering adding different compounds to improve its therapy, which involves removing a patient’s stem cells that make red blood cells, modifying them with a normal gene to manufacture a protein that fights beta-thalassemia, and then infusing them back into the body. It’s a one-time treatment.

Two of the 13 patients have had serious side effects unrelated to treatment, according to a separate release from the American Society of Hematology.

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