Despite documented laboratory and clinical benefits of hydroxyurea for children with sickle cell anemia (SCA), the drug's long-term safety and efficacy remains poorly defined. The HUSOFT trial and extension study examined feasibility, toxicity, and hematological efficacy of hydroxyurea in infants with SCA. This report describes HUSOFT participants who have continued hydroxyurea therapy for 15 years. With IRB approval, medical records were reviewed for clinical, laboratory, and growth parameters. Twenty-eight infants enrolled in the original 2-year HUSOFT study received open-label liquid hydroxyurea at 20 mg/kg/day; 17 completed the extension study with dose escalation to 30 mg/kg/day. Eight of these 17 (6 girls and 2 boys, all HbSS) have continued on daily hydroxyurea for at least 15 years (median age at last follow-up 17.6 years) without interruption. All hematologic indices (Hb concentration, mean corpuscular volume (MCV), fetal hemoglobin) showed sustained effect after 15 years. The median maximum tolerated dose of hydroxyurea has decreased from 30 to 26 mg/kg/day (range 19.5-31.2); neutropenia [absolute neutrophil count (ANC)<1.0×10⁹/L] prompting temporary drug discontinuation occurred a total of 10 times in 4 subjects and there was no severe neutropenia (ANC<0.5×10⁹/L). Growth rates over 15 years continued at the 50th percentile for both height and weight, and puberty occurred without delay (age range 10-14 years). There were 5.1 vaso-occlusive events (pain and acute chest syndrome)/100 patient years, 7.3 packed red blood cell transfusions/100 patient years. No malignancies, strokes, or deaths occurred. At last follow up, all subjects were at appropriate grade level (10-12 grade) with no history of repeated grades. A cohort of young teenagers with SCA who initiated treatment in infancy have had sustained and continued hematological benefits for a decade and a half. Growth and sexual development are normal and comparable to the general pediatric population. Continuous hydroxyurea therapy since infancy appears safe and efficacious in SCA.

Ischaemic stroke is a common complication of sickle cell disease (SCD) and without intervention can affect 11% of children with SCD before the age of 20. Within the Trans-Omics for Precision Medicine (TOPMed), a genome-wide association study (GWAS) of ischaemic stroke was performed on 1333 individuals with SCD from Brazil (178 cases, 1155 controls). Via a novel Cox proportional-hazards analysis, we searched for variants associated with ischaemic stroke occurring at younger ages. Variants at genome-wide significance (p < 5 × 10-8 ) include two near genes previously linked to non-SCD early-onset stroke (<65 years): ADAMTS2 (rs147625068, p = 3.70 × 10-9 ) and CDK18 (rs12144136, p = 2.38 × 10-9 ). Meta-analysis, which included the independent SCD cohorts Walk-PHaSST and PUSH, exhibited consistent association for variants rs1209987 near gene TBC1D32 (p = 3.36 × 10-10 ), rs188599171 near CUX1 (p = 5.89 × 10-11 ), rs77900855 near BTG1 (p = 4.66 × 10-8 ), and rs141674494 near VPS13C (1.68 × 10-9 ). Findings from this study support a multivariant model of early ischaemic stroke risk and possibly a shared genetic architecture between SCD individuals and non-SCD individuals younger than 65 years.

National evidence-based guidelines recommend offering hydroxyurea to patients with sickle cell anemia 9 months of age and older using shared decision making, but offer no strategies to aid implementation. We developed a hydroxyurea multicomponent decision aid via a needs assessment, clinic observations, and iterative feedback to address parent decision needs and promote a discussion between clinicians and parents. A total of 75 parents and 28 clinicians participated across all phases. The decision aid was rated as useful. Hydroxyurea knowledge improved and decisional conflict decreased supporting the potential for use to facilitate shared decision making in pediatric sickle cell anemia.