Increasing fetal hemoglobin in sickle cell disease fact sheet

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Increasing fetal hemoglobin in sickle cell disease

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April 23, 2025

What is sickle cell disease?

Sickle cell disease is a group of blood disorders affecting hemoglobin, a protein responsible for transporting oxygen in red blood cells. In individuals with the condition, dysfunctional hemoglobin causes red blood cells to become deformed (sickle-shaped). This creates blood flow blockages throughout the body and related serious symptoms, including pain, anemia and infections. The condition also causes damage to organs, including the bones, spleen, liver, brain, lungs, kidneys and joints.^1-3

Sickle cell disease is an inherited condition caused by a mutation in the adult hemoglobin gene (HbS), which causes the production of hemoglobin that does not function properly.⁴

Understanding the impact

People with sickle cell disease experience sudden and severe episodes of pain as a result of blocked blood flow, which can require medical attention.^1,4-6

Nearly all patients will visit
the emergency department
at least 2-3 times per year
and be hospitalized at least
once a year

About 30% of patients report
experiencing pain every day,
while more than 50%
report experiencing
pain half of the time

The frequency of pain
crises varies widely;
some individuals can have
6 or more each year

Sickle cell disease affects about 100,000 individuals in the US and nearly 8 million globally; it is most common in people of African, Middle Eastern, Mediterranean, Central and South American and South Asian descent.^2,7

In the US, life expectancy of those with sickle cell disease is more than 20 years lower than average.²

The condition significantly affects quality of life and patients often have trouble receiving medical care due to stigma and bias.^1,4

Widely available treatment strategies focus only on managing pain and preventing complications.^1,4

As a result, a significant need exists for new,
effective disease-modifying therapies.

What is fetal hemoglobin (HbF)?

The body produces a different form of hemoglobin during fetal development and in the first 6 months of life outside the womb, called fetal hemoglobin (HbF). After birth, HbF declines significantly, with the switch being made to adult hemoglobin (HbS) through activation of certain genes. HbS then makes up almost all of the body’s hemoglobin going forward.⁸

Graphic of eukaryotic translation initiation factor 2B (eIF2B).

In patients with sickle cell disease, only the HbS form of hemoglobin is dysfunctional. While the HbF form of hemoglobin is unaffected, it is no longer produced in most cases.⁹

Increasing HbF

Researchers are investigating ways to revert the body’s production of hemoglobin back to HbF, ultimately increasing the percentage of functional hemoglobin in the body.

This research approach is based on causal human biology^8,10:

Some individuals with sickle cell disease naturally continue to produce HbF into adulthood
These individuals with a higher proportion of HbF generally have milder disease, experiencing less severe symptoms

Genetic and clinical data from certain populations of people with sickle cell disease have shown that achieving at least 30% of hemoglobin production from HbF could eliminate symptoms for patients.¹¹

Researchers at Bristol Myers Squibb are investigating the ability of targeted protein degraders, specifically molecular glue degraders, to eliminate key genetic regulators that traditionally turn down production of hemoglobin from HbF. This could increase HbF levels into a range that may alleviate symptoms, associated organ damage and early mortality in people with sickle cell disease.

Protein degraders harness the cell’s own degradation machinery to break down therapeutically relevant proteins that were previously considered “undruggable”.

Bristol Myers Squibb is building on decades of unique research and clinical experience in protein degradation to discover and develop innovative medicines that could transform patient outcomes in some of the most complex diseases of our time, such as sickle cell disease.

References

U.S. Department of Health and Human Services. Last updated September 30, 2024. What is sickle cell disease? National Heart Lung and Blood Institute. https://www.nhlbi.nih.gov/health/sickle-cell-disease.
Accessed February 18, 2025.
U.S. Centers for Disease Control and Prevention. Last updated May 15, 2024. Data and statistics on sickle cell disease. https://www.cdc.gov/sickle-cell/data/index.html. Accessed February 27, 2025.
Bender MA, Carlberg K. Sickle Cell Disease. 2003 Sep 15 [updated 2025 Feb 13]. In: Adam MP, Feldman J, Mirzaa GM, Pagon RA, Wallace SE, Amemiya A, editors. GeneReviews® [Internet].
Seattle (WA): University of Washington, Seattle; 1993–2025.
Kato GJ, et al. Sickle cell disease. Nat Rev Dis Primers. 2018;4(18010):1-22.
Chennapragada SS, et al. Characteristics and Trends of Hospitalizations for Sickle-Cell Related Complications. Blood 2023; 142 (Supplement 1): 2305.
Maakaron JE, et al. Sickle Cell Disease (SCD) Clinical Presentation. https://emedicine.medscape.com/article/205926- clinical. Accessed March 19, 2025. Last updated Jan 23, 2025.
Thomson AM, et al. Global, regional, and national prevalence and mortality burden of sickle cell disease, 2000–2021: A systematic analysis from the global burden of disease study 2021. The Lancet Haematology. 2023;10(8).
Kaufman DP, Khattar J, Lappin SL. Physiology, Fetal Hemoglobin. [Updated 2023 Mar 20]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-.
Available from: https://www.ncbi.nlm.nih.gov/books/NBK500011/.
Akinsheye I, et al. Fetal hemoglobin in sickle cell anemia. Blood. 2011;118(1):19-27.
Steinberg MH. Fetal hemoglobin in sickle cell anemia. Blood. 2020;136(21):2392-2400.
Steinberg MH, et al. Fetal hemoglobin in sickle cell anemia: a glass half full? Blood. 2014;123(4):481-5.

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What is sickle cell disease?

Sickle cell disease is an inherited condition caused by a mutation in the adult hemoglobin gene (HbS), which causes the production of hemoglobin that does not function properly.4

Understanding the impact

People with sickle cell disease experience sudden and severe episodes of pain as a result of blocked blood flow, which can require medical attention.1,4-6

Nearly all patients will visit the emergency department at least 2-3 times per year and be hospitalized at least once a year

About 30% of patients report experiencing pain every day, while more than 50% report experiencing pain half of the time

The frequency of pain crises varies widely; some individuals can have 6 or more each year

Sickle cell disease affects about 100,000 individuals in the US and nearly 8 million globally; it is most common in people of African, Middle Eastern, Mediterranean, Central and South American and South Asian descent.2,7

In the US, life expectancy of those with sickle cell disease is more than 20 years lower than average.2

The condition significantly affects quality of life and patients often have trouble receiving medical care due to stigma and bias.1,4

Widely available treatment strategies focus only on managing pain and preventing complications.1,4

As a result, a significant need exists for new, effective disease-modifying therapies.

What is fetal hemoglobin (HbF)?

In patients with sickle cell disease, only the HbS form of hemoglobin is dysfunctional. While the HbF form of hemoglobin is unaffected, it is no longer produced in most cases.9

Increasing HbF

Researchers are investigating ways to revert the body’s production of hemoglobin back to HbF, ultimately increasing the percentage of functional hemoglobin in the body.

This research approach is based on causal human biology8,10:

Genetic and clinical data from certain populations of people with sickle cell disease have shown that achieving at least 30% of hemoglobin production from HbF could eliminate symptoms for patients.11

Protein degraders harness the cell’s own degradation machinery to break down therapeutically relevant proteins that were previously considered “undruggable”.

Bristol Myers Squibb is building on decades of unique research and clinical experience in protein degradation to discover and develop innovative medicines that could transform patient outcomes in some of the most complex diseases of our time, such as sickle cell disease.

Sickle cell disease is an inherited condition caused by a mutation in the adult hemoglobin gene (HbS), which causes the production of hemoglobin that does not function properly.⁴

People with sickle cell disease experience sudden and severe episodes of pain as a result of blocked blood flow, which can require medical attention.^1,4-6

Nearly all patients will visit
the emergency department
at least 2-3 times per year
and be hospitalized at least
once a year

About 30% of patients report
experiencing pain every day,
while more than 50%
report experiencing
pain half of the time

The frequency of pain
crises varies widely;
some individuals can have
6 or more each year

Sickle cell disease affects about 100,000 individuals in the US and nearly 8 million globally; it is most common in people of African, Middle Eastern, Mediterranean, Central and South American and South Asian descent.^2,7

In the US, life expectancy of those with sickle cell disease is more than 20 years lower than average.²

The condition significantly affects quality of life and patients often have trouble receiving medical care due to stigma and bias.^1,4

Widely available treatment strategies focus only on managing pain and preventing complications.^1,4

As a result, a significant need exists for new,
effective disease-modifying therapies.

In patients with sickle cell disease, only the HbS form of hemoglobin is dysfunctional. While the HbF form of hemoglobin is unaffected, it is no longer produced in most cases.⁹

This research approach is based on causal human biology^8,10:

Genetic and clinical data from certain populations of people with sickle cell disease have shown that achieving at least 30% of hemoglobin production from HbF could eliminate symptoms for patients.¹¹