Therapeutic modalities of deferiprone in Parkinson's disease: SKY and EMBARK studies

Abstract

Background: Reducing nigrostriatal iron overload reduces neuronal loss in Parkinson's disease (PD) models. Objective: Examine the safety and efficacy of deferiprone in reducing motor disability progression in dopaminergic-treated and treatment-naïve patients with early-stage PD. Methods: Two phase II, multicenter studies, SKY and EMBARK, enrolled patients diagnosed with early PD (<3 years from screening). In SKY, patients on stable dopaminergic therapy were randomized 1:1 to one of four dosage (or placebo-matching) cohorts (300, 600, 900, 1200 mg twice daily [BID]) for 9 months. EMBARK enrolled patients on stable dopaminergic therapy or treatment-naïve patients and received 15 mg/kg BID. For both studies, the primary outcome was the change from baseline to month 9 in motor examination score (Movement Disorder Society-Unified Parkinson's Disease Rating Scale [MDS-UPDRS] Part III). ClinicalTrials.gov: NCT02728843; ANZCTR: ACTRN12617001578392. Results: Overall, 140 patients were randomized in SKY (28 per cohort). Thirty-six patients enrolled in EMBARK (27 dopaminergic-treated; 9 treatment-naïve). In the SKY study, all doses showed the same worsening as the placebo group, with the exception of the 600 mg dose, which was associated with non-significant reductions in MDS-UPDRS Part III least-squares mean (LSM) between baseline and 9 months (−2–8 points versus placebo). In EMBARK, LSM (SE) changes from baseline in MDS-UPDRS Part III were nonsignificant (–1.6 [1.7]) and significant (8.3 [3.9]) for dopaminergic-treated and treatment-naïve patients, respectively, the latter indicating disease worsening. Adverse events possibly related to deferiprone were reported in 35.7%–88.9% across all deferiprone groups vs. 42.9% for placebo. Conclusions: SKY and EMBARK studies indicate that deferiprone combined with L-dopa does not provide significant motor function benefit, while the absence of L-dopa treatment worsens symptoms.