Chelsea refines droxidopa pivotal plans
This article was originally published in Pharmaceutical Approvals Monthly
Executive Summary
After meeting with FDA, Chelsea Therapeutics is unrolling a series of changes to its registrational studies for their lead candidate, droxidopa, in the treatment of symptomatic neurogenic orthostatic hypotension - to "further de-risk and maximize the potential significance of the outcome" of the Phase III program. For their ongoing Study 301, Chelsea will modify the primary endpoint and enroll an additional 24 patients to increase the power of the study. The revised primary endpoint will be the relative mean change in the Orthostatic Hypotension Questionnaire composite score between droxidopa and placebo; the OHQ composite score is a single endpoint that incorporates the average of the composition orthostatic hypotension symptom assessment (OHSA) score and the composite orthostatic hypotension daily activities scale score. Chelsea's first Phase III study in NOH (Study 302) failed to achieve statistical significance using only one item from the OHSA as the primary endpoint. "FDA agreed that the revised primary endpoint reflects a more comprehensive global assessment of the clinical benefit of droxidopa for treatment of symptomatic NOH in primary autonomic failure, a heterogeneous population consisting of patients suffering from Parkinson's disease, multiple system atrophy and pure autonomic failure, and would therefore be suitable for supporting a symptomatic claim," the firm said. Though the failed Study 302 cannot serve as a pivotal trial, FDA will consider the safety and efficacy data as supportive. The agency did recommend that Chelsea conduct a confirmatory study to support an NDA filing, but indicated it could be contained to a small, highly enriched, homogenous patient population. Chelsea will re-open enrollment in Study 301 at a few North American centers and hopes to complete the recruitment by the end of the second quarter 2010, which would mean top-line results could be available in the third quarter. Chelsea is also studying droxidopa, a synthetic catecholamine that is directly converted to norepinephrine, in Phase II for fibromyalgia and intradialytic hypotension