Global Blood Therapeutics has secured US approval for Oxbryta, the second new treatment for sickle cell disease (SCD) to get a nod from the FDA this year.
The regulator had cleared Oxbryta (voxelotor) for the treatment of sickle cell disease in patients aged 12 and over, and according to the SCD Association of America is a therapy that promises to ‘change the course’ of the disease.
Oxbryta is designed to prevent the polymerisation of the haemoglobin molecule that causes red blood cells to deform into the characteristic sickle shape in SCD, striking at the root cause of the disease.
Acting FDA Commissioner Brett Giroir said the new drug “provides additional hope to the 100,000 people in the US, and the more than 20 million globally, who live with this debilitating blood disorder”.
Treatment with the once-daily, oral drug will be priced at $125,000 per year, discounted to around $96,000 for most health plans, said GBT’s chief executive Ted Love.
He estimated that around half of SCD patients will be covered by the federal Medicaid reimbursement system and another 15% by Medicare for low-income individuals.
Oxbryta’s approval comes a few weeks after the FDA cleared Novartis’ anti-P-selectin antibody Adakveo (crizanlizumab), to reduce one of the most serious complications of SCD, namely the excruciatingly painful vaso-occlusive crises (VOCs) that result when the misshapen red cells block blood vessels.
Adakveo’s wholesale acquisition cost (WAC) has been set at $2,357 per vial, which equates to around between $7,071 and $9,428 per month – or around $85,000 to $113,00 per year – depending on patient weight. Novartis has said it thinks its new drug has $1bn-plus sales potential.
The approval is based on the results of the HOPE trial, which found that Oxbryta was able to achieve an increase in the haemoglobin response rate – defined as an increase of at least one gram per decilitre after 24 weeks – compared to placebo. GBT’s drug also reduced red cell destruction (haemolysis) compared to the control group.
Oxbryta has been given a green light based on that surrogate endpoint under the FDA’s subpart H pathway, which aims to speed up the review of drugs for rare diseases that have few treatment options.
GBT will have to carry out additional trials to make sure that haemoglobin response translates into clinical benefits such as a reduction in VOCs.
Following behind the new drug treatments for CD are gene therapies that promise to deliver a one-shot treatment for the disease.
One potential gene therapy – Bluebird Bio’s Zynteglo – was given conditional approval in Europe for another blood disease called beta thalassaemia in June and is in late-stage development for SCD.