How Hydroxyurea and Longitudinal Research Are Transforming Pediatric Sickle Cell Disease Care
Key Insights
The BABY HUG study demonstrated that hydroxyurea safely reduces hospitalizations, pain crises, and organ damage in infants and young children with sickle cell disease (search).
St. Jude's SCCRIP longitudinal study follows over 1,800 participants to understand why disease severity varies and to guide personalized treatment decisions.
Researchers are using AI and computational approaches to identify patterns that may predict severe disease and match patients to optimal therapies, including emerging gene-based treatments.
For Courtney, a 25-year-old investment banker living in New York City, sickle cell disease (search) has been a lifelong companion — but not a limitation. Diagnosed before birth with the genetic blood disorder, she enrolled at age 3 in a groundbreaking St. Jude Children's Research Hospital study that would reshape how young children with sickle cell disease are treated. That study, known as BABY HUG, tested whether hydroxyurea — a medication previously reserved mainly for adults — could safely benefit infants and young children.
The results were transformative. The study showed that hydroxyurea reduced hospitalizations, pain crises and organ damage in pediatric patients. The medication works by increasing production of fetal hemoglobin (search), a form of hemoglobin babies naturally make before birth that helps prevent red blood cells from sickling. Courtney took the medicine daily, helping her manage symptoms throughout early childhood.
A foundation built over decades
St. Jude's commitment to sickle cell disease (search) predates the hospital's opening. The institution received its first research grant for the condition in 1958, and today it operates one of the largest sickle cell programs in the country, treating approximately 850 patients. Hydroxyurea became a cornerstone of early intervention after the BABY HUG findings, giving families like D'Yana's a tangible tool when both of her daughters — Ari'Yanna and Ariyah — were diagnosed with the disease.
"When they were babies and toddlers, managing my daughters' sickle cell complications was challenging because they were too young to put words to pain," D'Yana recalled. Ari'Yanna started hydroxyurea at 10 months old; her younger sister Ariyah followed the same path. The disease manifested differently in each child — Ari'Yanna felt pain most in her arms and hands, while Ariyah experienced it in her legs. Ariyah, now 9, also visits St. Jude monthly for transfusions to help prevent sickled cells from blocking blood vessels and reduce her risk of stroke.
Following patients over a lifetime
More than two decades after BABY HUG, Courtney is now participating in a different kind of study — one designed to answer questions that shorter trials cannot address. The Sickle Cell Clinical Research and Intervention Program, or SCCRIP, is a long-term study launched in 2014 that follows people with sickle cell disease (search) over many years to better understand how the condition affects patients throughout their lives.
Although sickle cell disease (search) is caused by a single genetic mutation, its effects vary widely from person to person. Some patients experience frequent, severe complications, while others face milder symptoms. SCCRIP was created to help researchers understand why. The study now includes more than 1,800 participants from St. Jude and select affiliate locations, generating data that has supported dozens of research papers.
"When you follow patients over time, you begin to see patterns that simply aren't visible in shorter studies," said Deepa Manwani, MD, medical director of the St. Jude Comprehensive Sickle Cell Disease (search) Program and principal investigator of SCCRIP. "That kind of longitudinal data helps us understand not only how the disease progresses, but how different treatments affect patients over the long term and if there are clues early in life that might predict worse outcomes."
The study captures far more than traditional clinical information. Researchers analyze genetic data, gene activity, proteins and other biological signals to build a more complete picture of how sickle cell disease (search) affects each individual patient. Manwani and her colleagues are working to use advanced computational approaches, including artificial intelligence, to identify patterns that may help predict who is at higher risk for severe disease and which treatments are most likely to benefit specific patients.
Guiding decisions in the gene therapy era
Knowledge about how sickle cell disease (search) impacts patients differently is particularly important as new treatments, including gene-based therapies, emerge. Gene therapies aim to correct or counteract the faulty gene responsible for sickle cell disease, potentially offering long-term relief or even a cure. However, current gene therapy approaches carry significant risks.
Before treatment, patients often must undergo conditioning — a process using chemotherapy or radiotherapy to clear out existing blood-forming cells. Conditioning can cause serious side effects, including risks of infection, organ damage and infertility. This means gene therapy may be a poor fit for some patients, but data is lacking to show which patients would experience the most benefit from currently available gene therapy options and when.
"Predicting disease severity in childhood will allow for transformative therapies to be administered before the cumulative organ damage from the disease adds to the risk of intensive treatments," said Manwani.
St. Jude has seen the value of this tailored-treatment approach in other areas, including pediatric brain cancers such as medulloblastoma. Once treated as a single disease, medulloblastoma is now understood to include multiple subtypes that respond differently to therapy — an insight that has led to more precise treatments and better outcomes. Researchers hope a similar strategy can help transform sickle cell care.
There is also hope that SCCRIP data will uncover new strategies for treating or curing sickle cell disease (search) that carry fewer side effects. Researchers at St. Jude are already studying alternative gene-based approaches that could make treatment safer and more accessible. One promising strategy, known as in-vivo gene therapy, would deliver treatment through an intravenous medication that alters blood-forming cells inside the body — potentially eliminating the need for conditioning altogether.
Living beyond the diagnosis
For the families at the center of this research, progress brings hope for a different future. Ari'Yanna, now 11, and Ariyah, now 9, are both participants in SCCRIP, contributing to the knowledge that may one day transform care. They play basketball, run track, and perform as majorettes. When friends express surprise at their diagnosis, Ari'Yanna has a ready response: "I have sickle cell. Sickle cell doesn't have me."
Courtney dreams of traveling to Greece, South Africa and Southeast Asia. She wants to be a wife and a mother. "I really want to have a family," she said. "I want to talk to my kids about sickle cell — about the fact that it's hereditary. And I hope that by then, I won't know just one person who's been cured. I hope I'll know many."