Efficacy and safety of thalidomide with hydroxyurea in sickle cell anemia: a quasi-experimental clinical trial.

Background: The clinical course of sickle cell anemia (SCA) is variable, with chronic hemolysis and end-organ damage caused by microvascular occlusion. We evaluated the efficacy and safety of thalidomide plus hydroxyurea (HU) compared with HU alone to determine whether the combination provides a superior clinical benefit and safety profile.

Methods: This was an open-label quasi-experimental clinical trial (Clinical Trials Registry of India, CTRI Registration Number 2023/04/065682). Patients with SCA aged > 12 years and postmenopausal females aged > 45 years were allocated 1:1 to receive either HU (20 mg/kg/day) and thalidomide (50 mg/day) in Group A or HU (20 mg/kg/day) only in Group B.

Results: The frequency of vaso-occlusive crises (VOCs), transfusion requirements, variations in hematological parameters (hemoglobin [Hb], fetal hemoglobin [HbF], and sickle hemoglobin [HbS]), and side effects between the groups were assessed over 12 months. Repeated-measures analysis of variance was used to determine changes across the observation period. The mean age of the 66 patients diagnosed with SCA (homozygous HbS mutation) was 32.9 (standard deviation ± 11.5) years, and 57.6% were males. Over the 12-month observation period, Group A had significantly fewer VOCs (3.48 ± 2.81) and packed red blood cell transfusions (3.61 ± 2.19) than Group B (11.36 ± 4.20 VOCs; 13.27 ± 3.70 transfusions) (p = 0.0001). There was a significant increase in Hb (8.2 ± 1.8 to 11.8 ± 1.2 g/dL), a decrease in HbS% (72.5 ± 5.5 to 64.5 ± 5.4), and a rise in HbF% (18.9 ± 5.1 to 28.4 ± 5.6) (p < 0.0001) in Group A.

Conclusion: Combining thalidomide with HU significantly reduced VOCs and transfusion requirements, improved Hb and HbF%, and decreased HbS levels.