Sickle Cell Patient with Severe Anemia Rapidly Improves with Voxelotor, Case Study Shows

Catarina Silva, MSc avatar

by Catarina Silva, MSc |

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Global Blood Therapeutics (GBT) reported a case study in which a sickle cell disease (SCD) patient was granted compassionate access to the company’s ongoing Phase 3 HOPE study of voxelotor (NCT03036813). The patient had severe, transfusion-refractory anemia and experienced rapid improvements with the therapy.

The company described the case study in an oral presentation at the Sickle Cell Disease Association of America’s (SCDAA) 45th Annual National Convention in Atlanta.

Red blood cells contain hemoglobin, which allows them to carry oxygen. In SCD, the hemoglobin is abnormal and makes the cells adopt an unusual shape called “sickle.” These sickle cells are sticky and inflexible. When traveling through the blood vessels they can stick to vessel walls and clog blood flow, which in turn stops oxygen delivery to nearby tissues.

“Individuals living with SCD need innovative therapies that can address the underlying cause of the disease and help their quality of life. This is particularly true for SCD patients with severe anemia, for whom treatment options are extremely limited,” Ted W. Love, MD, president and chief executive officer of GBT, said in a news release.

The U.S. Food and Drug Administration (FDA) developed the option of compassionate access, also called “compassionate use,” to enable patient enrollment in an “impossible scenario,” i.e. when a patient is ineligible for ongoing trials or no ongoing trials exist. With this measure, patients may be able to receive the investigational therapy when appropriate. 

In this case, the patient was a 67-year-old male with severe anemia resistant to transfusion due to red cell antibodies that developed following multiple blood transfusions. He also needed supplemental oxygen therapy due to moderate chronic obstructive pulmonary disease (COPD). Other clinical history details include recurrent and frequent pain exacerbations, extreme fatigue, and clinical depression.

After about two weeks of receiving 900 mg of voxelotor orally once daily, the patient showed an improvement in hemoglobin levels, pain, fatigue, and overall mental health as measured by the Patient Health Quality-9 score.

Nine weeks into treatment, the voxelotor dose was increased to 1,500 mg daily, which led to the only treatment-related side effect, grade 2 diarrhea. This was resolved by returning to 900 mg.

At 65 weeks, the patient’s blood oxygen levels improved to 96mmHg from 86mmHg at baseline in a standard walk test. As a result, continuous oxygen supplementation was discontinued.

After 17 months of sustained improvements, the patient is still on treatment thanks to the compassionate use access.

“This severely ill SCD patient’s clinical response, assessed by both objective and subjective measures, illustrates why we are encouraged by the voxelotor program. We plan to present additional data from other severely ill sickle cell patients who have received voxelotor via single-patient compassionate access treatment at FSCDR at an upcoming medical meeting. Of course, controlled clinical trials are needed to assess the efficacy and safety of voxelotor in SCD patients, including those with severe anemia,” Love noted.

“Coming from an organization committed to supporting innovative research in SCD to help maximize quality of life and improve survival for the generations of people affected with this disease, we are grateful to companies such as GBT for their commitment to advancing the development of new treatments for the SCD community,” said Lanetta Bronté, MD, MPH, MSPH, founder of the Foundation for Sickle Cell Disease Research (FSCDR), and an author of the case study.