New treatment for sickle cell disease

News 17/12/2021

EMA has recommended granting a marketing authorisation in the EU for Oxbryta (voxelotor) for the treatment of haemolytic anaemia (excessive breakdown of red blood cells) due to sickle cell disease in patients 12 years of age and older. Oxbryta is to be used on its own or in combination with hydroxycarbamide (also known as hydroxyurea).

Sickle cell disease is a genetic condition in which the red blood cells become rigid and sticky and change from being disc-shaped to being crescent-shaped (like a sickle). The change in shape is caused by the presence of an abnormal form of haemoglobin (the protein in red blood cells that carries oxygen around the body).

In patients with sickle cell anaemia, the abnormal sickle-shaped red blood cells block the blood vessels, restricting the flow of blood to organs, such as the heart, lungs and spleen. This situation causes episodes of acute pain called vaso-occlusive crisis (VOC). Furthermore, these abnormal red blood cells are destroyed at a faster rate than normal, leading to a condition called haemolytic anaemia. Vaso-occlusive crisis (VOC) and haemolytic anaemia are the most common complications of sickle cell disease and are frequent causes of visits to emergency departments and hospitalisation.

Currently, most patients with sickle cell disease are treated with hydroxyurea and crizanlizumab, medicines for preventing VOC. However, there is a high unmet need for medicines to treat haemolytic anaemia, which is experienced to various degrees by all patients. Available treatment options are limited to blood transfusions and allogenic hematopoietic stem cell transplantation (a procedure where the patient receives stem cells to help the bone marrow produce healthy blood cells). Therefore, new medicines for this manifestation of the disease are needed.

The active substance of Oxbryta is voxelotor, a small molecule which attaches to and stabilises haemoglobin, preventing haemoglobin polymerization (i.e. formation of abnormal haemoglobin) that causes the red blood cells to become sickle shaped.

Oxbryta was supported through EMA’s Priority Medicines (PRIME) scheme, which provides early and enhanced scientific and regulatory support for promising medicines with a potential to address unmet medical needs. Representatives of patient organisations were also consulted during the assessment of benefits and risks of Oxbryta to share their unique real-life perspectives and ensure that patients’ needs are taken into account in the regulatory decision-making process.

The main study that EMA’s recommendation is based on was a Phase 3, randomised, double blind, placebo-controlled, multicentre study. The study investigated the safety and efficacy of voxelotor in 274 patients with sickle cell disease aged 12 to 65 years. Patients enrolled in the clinical trial had a baseline haemoglobin level between 5.5 and 10.5 g/dL. 90 patients received 1500 mg of voxelotor, 92 patients received 900 mg of voxelotor and 92 patients received a placebo. After 24 weeks of treatment, 51.1% of patients treated with 1,500 mg of voxelotor had a greater than 1 g/dl increase in their haemoglobin levels compared to 6.5% of those receiving placebo. These results were observed when Oxbryta was used on its own or in combination with hydroxyurea, which is the standard treatment for patients with sickle cell disease.

The most common side effects reported in clinical trials for Oxbryta included headache, diarrhoea and abdominal pain.

The opinion adopted by the CHMP is an intermediary step on Oxbryta’s path to patient access. The CHMP opinion will now be sent to the EC for the adoption of a decision on the EU-wide marketing authorisation. Once a marketing authorisation has been granted, decisions about price and reimbursement will take place at the level of each Member State, taking into account the potential role/use of this medicine in the context of the national health system of that country.


  1. The applicant for Oxbryta is Global Blood Therapeutics Netherlands B.V.
  2. Oxbryta was accepted into the PRIME scheme on 23 June 2017.
  3. Oxbryta was designated as an orphan medicinal product on 18 November 2016.

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