Researchers have compared the phase II and phase III ( EMPOWER ) studies of Dexpramipexole in amyotrophic lateral sclerosis ( ALS ) and have evaluated potential EMPOWER responder subgroups and biomarkers based on significant inter-study population differences.
In a post hoc analysis, researchers compared the baseline population characteristics of both Dexpramipexole studies and analyzed EMPOWER efficacy outcomes and laboratory measures in subgroups defined by significant inter-study differences.
Results showed that, compared with phase II, the proportion of El Escorial criteria ( EEC ) definite participants decreased ( p = 0.005 ), Riluzole ( Rilutek ) use increased ( p = 0.002 ), and mean symptom duration increased ( p = 0.037 ) significantly in EMPOWER.
Baseline creatinine ( p less than 0.001 ) and on-study creatinine change ( p less than 0.001 ) correlated significantly with ALSFRS-R in EMPOWER.
In the EMPOWER subgroup defined by EEC-definite ALS, Riluzole use, and less than median symptom duration ( 15.3 months ), Dexpramipexole-treated participants had reduced ALSFRS-R slope decline ( p = 0.015 ), decreased mortality ( p = 0.011 ), and reduced creatinine loss ( p = 0.003 ).
In conclusion, significant differences existed between the phase II and EMPOWER study populations in ALS clinical trials of Dexpramipexole.
In a post hoc analysis of EMPOWER subgroups defined by these differences, potential clinical benefits of Dexpramipexole were identified in the subgroup of Riluzole-treated, short-symptom duration, EEC-definite ALS participants.
Creatinine loss correlated with disease progression and was reduced in Dexpramipexole-treated participants, suggesting it as a candidate biomarker. ( Xagena )
Bozik ME et al, Amyotroph Lateral Scler Frontotemporal Degener 2014;15:406-413