Praxis Precision Medicines announces data from Essential1 study

Praxis Precision Medicines announced further data from two additional analyses of the Essential1 study for ulixacaltamide. Open-Label Extension: Following completion of the initial 8-week double-blind treatment phase in Essential1, eligible patients had the option to continue their access to ulixacaltamide in an open-label extension phase. Participants who continued to the OLE phase remained blinded for a 6-week lead-in period. There was no change to the overall safety results through 14 weeks of treatment. 65 patients who completed the double-blinded portion of Essential1 were eligible to participate in the OLE2 and completed the week 14 assessment. Patients who were eligible and continued on ulixacaltamide experienced an additional mean improvement in mADL111 of 1.7 points from 3.09 at Week 8 to 4.81 after 14 weeks of treatment. Patients who switched from placebo during the double-blind phase of Essential1 to ulixacaltamide treatment during the OLE 6-week lead-in experienced mean improvement in mADL11 of 3.15 points, from 1.21 at Week 8 to 4.36. Randomized Withdrawal Sub-Study: Following the announcement of the Essential1 study topline results, Praxis amended the open-label protocol to further assess the criteria to be used in the upcoming randomized withdrawal Phase 3 study. In this sub-study, patients were re-randomized in a blinded fashion to either receive placebo or continue to receive ulixacaltamide. Twenty-one patients who completed assessments at week 14 of the OLE were eligible to participate in the blinded sub-study. Patients were evaluated weekly over a total of 6 weeks, with 11 patients assigned to ulixacaltamide and 10 to placebo for the initial 3-week period, crossing over to either placebo or ulixacaltamide for an additional 3-week period. Blinded rescue was triggered for patients on placebo if loss in the mADL11 exceeded 2 points at any timepoint. Patients who switched from ulixacaltamide to placebo experienced an average loss of effect in their mADL11 per week of 47%, compared to 6% improvement in global mean change per week for the periods receiving ulixacaltamide. In addition, 10 patients assigned to placebo met the rescue criteria to restart ulixacaltamide. 85% of the patients who received ulixacaltamide and 52% who received placebo maintained their mADL11 within 3 points compared to baseline, confirming the definition of patient stability to be used in the Phase 3 program. No new safety signals emerged and there was no change to the overall safety results observed in the 8-week double-blind treatment phase.