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Update on phase III clinical trial evaluating troriluzole for spinocerebellar ataxia.

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Published:25th May 2022

Biohaven Pharmaceutical Holding Company Ltd. announced top-line results from a Phase III clinical trial evaluating the efficacy and safety of its investigational therapy, troriluzole, in patients with spinocerebellar ataxia (SCA)

The primary endpoint, change from baseline to Week 48 on the modified functional Scale for the Assessment and Rating of Ataxia (f-SARA), did not reach statistical significance in the overall SCA population as there was less than expected disease progression over the course of the study. In the overall study population (N=213), the troriluzole and placebo groups each had mean baseline scores of 4.9 on the f-SARA and the two groups showed minimal change at the 48-week endpoint with f-SARA scores of 5.1 and 5.2, respectively (p=0.76).

Post hoc analysis of efficacy measures by genotype suggests a treatment effect in patients with the SCA Type 3 (SCA3) genotype, which represents the most common form of SCA and accounted for 41 percent of the study population. In the SCA3 subgroup, troriluzole showed a numerical treatment benefit on the change in f-SARA score from baseline to Week 48 compared to placebo (least squares [LS] mean change difference -0.55, nominal p-value = 0.053, 95% CI: -1.12, 0.01). SCA patients treated with troriluzole showed minimal disease progression over the study period.

Further, in patients in the SCA3 subgroup who were able to walk without assistance at baseline (i.e., f-SARA Gait Item score = 1), troriluzole demonstrated a greater numerical treatment benefit on the change in f-SARA score from baseline to Week 48 compared to placebo (LS mean change difference -0.71, nominal p-value = 0.031, 95% CI: -1.36, -0.07). Notably, the f-SARA is a novel, 16-point scale developed in collaboration with FDA as the primary outcome measure for this trial; the scale was designed to limit subjectivity of the scale and focus on functional aspects of the disease so that significant changes would be considered clinically meaningful.

Across all genotypes, patients who were able to ambulate at baseline (i.e., f-SARA Gait Item score = 1) showed a reduction in the relative risk of falls in troriluzole-treated patients versus placebo. Patient reported falls, as measured by adverse events reveal an approximately 58% reduction of fall risk in the troriluzole group (10% versus 23% AE incidence of falls in the troriluzole and placebo groups, respectively; nominal p=0.043). Overall, troriluzole demonstrated a favorable safety and tolerability profile, consistent with past clinical trial experience.

Jeremy Schmahmann, M.D., Professor of Neurology at Harvard Medical School and Founding Director of the Ataxia Center at Massachusetts General Hospital (MGH) commented with regard to the findings, "The importance of morbidity related to falls in this patient population cannot be overstated. The reduction of falls in the troriluzole group, combined with the progression of f-SARA scores in the untreated SCA3 group compared to SCA3 patients on troriluzole, demonstrates that SCA3 patients are experiencing a clinically meaningful improvement in ataxia symptoms on troriluzole treatment."

Condition: Spinocerebellar Ataxia
Type: drug

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