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Robust clinical and laboratory response to hydroxyurea using pharmacokinetically guided dosing for young children with sickle cell anemia
Author(s) -
McGann Patrick T.,
Niss Omar,
Dong Min,
Marahatta Anu,
Howard Thad A.,
Mizuno Tomoyuki,
Lane Adam,
Kalfa Theodosia A.,
Malik Punam,
Quinn Charles T.,
Ware Russell E.,
Vinks Alexander A.
Publication year - 2019
Publication title -
american journal of hematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.456
H-Index - 105
eISSN - 1096-8652
pISSN - 0361-8609
DOI - 10.1002/ajh.25510
Subject(s) - dosing , medicine , clinical endpoint , anemia , pharmacokinetics , population , clinical trial , hemoglobin , sickle cell anemia , pharmacology , disease , environmental health
Hydroxyurea is FDA‐approved and now increasingly used for children with sickle cell anemia (SCA), but dosing strategies, pharmacokinetic (PK) profiles, and treatment responses for individual patients are highly variable. Typical weight‐based dosing with step‐wise escalation to maximum tolerated dose (MTD) leads to predictable laboratory and clinical benefits, but often takes 6 to 12 months to achieve. The Therapeutic Response Evaluation and Adherence Trial (TREAT, NCT02286154) was a single‐center study designed to prospectively validate a novel personalized PK‐guided hydroxyurea dosing strategy with a primary endpoint of time to MTD. Enrolled participants received a single oral 20 mg/kg dose of hydroxyurea, followed by a sparse PK sampling approach with three samples collected over three hours. Analysis of individual PK data into a population PK model generated a starting dose that targets the MTD. The TREAT cohort (n = 50) was young, starting hydroxyurea at a median age of 11 months (IQR 9‐26 months), and PK‐guided starting doses were high (27.7 ± 4.9 mg/kg/d). Time to MTD was 4.8 months (IQR 3.3‐9.3), significantly shorter than comparison studies (p < 0.0001), thus meeting the primary endpoint. More remarkably, the laboratory response for participants starting with a PK‐guided dose was quite robust, achieving higher hemoglobin (10.1 ± 1.3 g/dL) and HbF (33.3 ± 9.1%) levels than traditional dosing. Though higher than traditional dosing, PK‐guided doses were safe without excess hematologic toxicities. Our data suggest early initiation of hydroxyurea, using a personalized dosing strategy for children with SCA, provides laboratory and clinical response beyond what has been seen historically, with traditional weight‐based dosing.