Alcobra announced Tuesday that it was terminating the development of its experimental extended-release formulation of metadoxine for adults with attention deficit-hyperactivity disorder (ADHD) after top-line results showed the drug failed to meet the primary endpoint of the Phase III MEASURE trial. Shares in the company fell as much as 53 percent on the news. 

The company explained that data analysis was conducted on the full analysis set of 283 participants, which includes all randomised subjects with at least one post-baseline efficacy assessment. Results illustrated that extended-release metadoxine failed to produce a significant difference in change from baseline of the investigator rating of the Conners' Adult ADHD Rating Scales (CAARS), versus placebo. Alcobra noted that the therapy was "generally well tolerated."

CEO Yaron Daniely remarked "we are exceedingly disappointed with these top-line results." He said "in the coming weeks, the company intends to review the full data set from MEASURE," adding that "consequently, we will evaluate our options and communicate our strategic plan to investors." 

In October, the company said the FDA issued a clinical hold on the MEASURE trial, citing "electrophysiological neurologic findings in previously submitted long-term animal studies with metadoxine." At the time, Alcobra pointed out that the US regulator had not referenced any clinical safety data observed in the MEASURE study or in previous human studies with the drug. Alcobra stated early January that the FDA had recently agreed to modify the full clinical hold to a partial hold to allow the company to conduct of a six-month Phase I safety trial in order "to directly assess the potential relevance of adverse findings observed in long-term, non-clinical studies of [extended-release metadoxine] with regard to human exposure."

Commenting on the MEASURE results, Piper Jaffray analyst Charles Duncan said "we're not particularly surprised by this outcome as the truncated dataset greatly reduced the power of this trial to demonstrate a significant impact on the CAARS." He added "Alcobra now plans to use its [approximately] $50 million in cash to execute on a new business plan, the details of which should become available during [this quarter]. 

Meanwhile, Daniely indicated that Alcobra will continue assessing the efficacy of extended-release metadoxine in the treatment of other conditions, including Fragile X syndrome, potentially in collaboration with a European partner. The therapy, also known as MG01CI, failed a mid-stage study in Fragile X syndrome in 2015.