GBT heads to FDA with sickle cell drug voxelotor

Global Blood Therapeutics (GBT) has persuaded the FDA to accept biomarker data from a phase III trial of sickle cell disease drug voxelotor as part of a filing for accelerated approval. The South San Francisco biotech says it will be able to file on the strength of data from a phase III trial showing that voxelotor can improve hemoglobin levels and reduce red blood cell destruction (haemolysis), rather than clinical endpoints such as a reduction in the painful vaso-occlusive crises (VOCs) that afflict sickle cell patients.
GBT will file under the FDA’s truncated subpart H approval pathway, used to hasten the approval of drugs for serious and rare diseases with inadequate treatment options, and won’t have to provide data on clinical endpoints until after the drug has been launched. The news came as GBT presented preliminary results from 154 adolescents and adults with sickle cell disease, treated with two doses of voxelotor or placebo, at the American Society of Haematology (ASH) congress in San Diego. All told, 65% of patients on the higher 1500 mg dose of voxelotor achieved a haemoglobin response, defined as an increase of at least one gram per decilitre after 24 weeks, which compared to 33% of the lower dose (900 mg) group and 10% of patients on placebo. In some cases, the improvements were seen in patients who were also being treated with hydroxyurea, the standard therapy.