* Co says one dose succeeds
* Plans to meet with FDA to discuss path forward
* Stock sinks 56.6 pct (Recasts lead; updates shares)
By Natalie Grover
May 1 (Reuters) - Neurotrope Inc's shares more than halved after data from a small trial on the company's Alzheimer's drug failed to impress investors, the latest in a series of setbacks in the quest for an effective treatment for the memory-robbing disease.
Two doses of Bryostatin-1 were tested against a placebo, in addition to the standard treatment, in 147 patients with moderate-to-severe disease over a twelve week period.
A total of 113 patients completed the study and Neurotrope said the higher 40 microgram (mcg) dose showed "very modest efficacy".
However, patients on the 20 mcg dose met the main goal by showing improvement on a scale called the Severe Impairment Battery (SIB), which is used to measure cognition levels, the company said.
Data showed a mean increase of 1.5 on the SIB, compared with a decrease in the placebo group of 1.1, or a p-value of less than 0.07.
When performing a hypothesis test, the p-value helps determine the significance of the results.
Statistical significance in late-stage trials is typically defined by a p-value of 0.05 or less, but this was more an exploratory mid-stage study and the data is encouraging, Chief Scientific Officer Daniel Alkon said on a call with analysts.
In patients who received the 20 mcg dose but did not complete the study, Bryostatin-1 failed to meet the main goal, the company added.
"This may not be what investors were expecting, and we expect some to view the p-values as a failure," Aegis Capital analyst Robert LeBoyer said.
In a longer study, "the decline in the placebo patients would be expected to widen the difference between the two groups, showing greater treatment effect and statistical significance," LeBoyer said.
The drug, which comes from a marine source, is designed to address an underlying cause of the disease by inducing growth of synapses in the brain and preventing cell death.
The compound was originally evaluated as a treatment for cancer. Following its failure as an oncology treatment, Neurotrope inked a deal to supply the expensive compound to National Cancer Institute (NCI).
Neurotrope, which now has an exclusive license for a synthetic version of the drug, hopes to discuss a path forward with the U.S. health regulator, it said.
Existing treatments only lessen symptoms or slow disease progression, and there is laundry list of crushing disappointments in the effort to find an effective way to reverse cognitive decline that affects more than 5 million Americans with Alzheimer's.
Neurotrope's shares fell as much as 56.6 percent to $8.16 in morning trading. (Reporting by Natalie Grover in Bengaluru; Editing by Saumyadeb Chakrabarty and Anil D'Silva)