About Sickle Cell Disease

Sickle cell disease (SCD) is a lifelong, inherited blood disorder that impacts hemoglobin, a protein found in red blood cells (RBCs) that carries oxygen throughout the body. The disease is caused when a person inherits two abnormal sickle cell genes, one from each parent.

In people with SCD, red blood cells lose their normal shape and become sickle-shaped and rigid. Sickle-shaped red blood cells get stuck in small blood vessels and block the flow of blood and oxygen to the body, which can cause severe pain and inflammation, leading to organ damage and stroke. Sickle-shaped red blood cells live about 20 days compared to 100 for normal red blood cells. When the body can’t replace the red blood cells fast enough, the ongoing shortage leads to anemia, a condition where a person has less energy and therefore tires more easily. SCD is a life-long illness that worsens over time, causing tremendous damage to the body.

People with SCD need safe and effective treatments that can attack the cause of the disease, reduce the complications, and improve the quality of their lives.


GBT is developing GBT440 as an oral, once-daily therapy for patients with sickle cell disease. GBT440 is designed to work by helping hemoglobin, the molecules inside red blood cells, hold onto more oxygen as the red blood cells travel through the body.  This keeps red blood cells in their normal shape and helps stop sickling. For more information on how GBT440 works view the mechanism of action fact sheet.

In recognition of the critical need for new treatments, the U.S. Food and Drug Administration (FDA) has granted GBT440 both Fast Track and Orphan Drug designation and the European Commission (EC) has designated GBT440 as an orphan medicinal product for the treatment of SCD.

Clinical Trials

The GBT HOPE Sickle Cell Disease program is evaluating whether GBT440 will be effective in reducing the damage the SCD causes to red blood cells and therefore, decrease the day-to-day symptoms of SCD in adolescents and adults who have the disease. The studies will also examine the effects of different doses of the investigational medication to determine the best dose.

We are currently enrolling patients in our Phase 3 HOPE (Hemoglobin Oxygen Affinity Modulation to Inhibit HbS PolymErization) Study. The HOPE Study is enrolling patients age 12 and older with SCD who have had at least one episode of vaso-occlusive crisis (VOC) in the previous year. We are also studying GBT440 in patients 12-17 years of age in the Phase 2a HOPE-KIDS 1 Study. 

For more information about our trials in SCD visit

Additional Resources

In an effort to provide patients and their families with access to the latest and most valuable resources related to SCD, we have compiled the following list of links. These links will take you away from the company’s website, but connect you to other trusted providers of information that we think may be useful to patients and their families.

Patient Advocacy Groups:

Government and International Agencies:

Scientific Societies/Organizations:

Additional Resources for SCD Information:

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