CAMBRIDGE, Mass. ( TheStreet) -- Sage Therapeutics (SAGE) announced Thursday that an injection of the experimental psychiatric drug SAGE-547 was more effective than a placebo in treating patients with essential tremors, a neurological condition which causes involuntary, rhythmic muscle shaking.
Tempered optimism is probably the best way to interpret the data from the small (only 25 patients were enrolled) exploratory study. On one measure of muscle tremor reduction assessed at 12 hours, twice the number of patients treated with SAGE-547 responded compared to placebo. The difference between SAGE-547 and placebo, however, was not statistically significant. On other measures of efficacy, SAGE-547 demonstrated a benefit over placebo that was barely statistically significant.
In an interview Wednesday afternoon, Sage CEO Jeff Jonas said the intention of the study from the beginning was to evaluate the feasibility of treating essential tremor patients with a drug like SAGE-547 that acts on the GABA neurotransmitter system in the brain, hoping to see clinical evidence of positive drug activity.
"The data that we're reporting is as clear a signal as one can get to move a drug forward. We're excited by it," said Jonas.
The signal of activity Jonas believes Sage sees with SAGE-547 in essential tremor may turn out to be real or a mirage. There's nothing definitive enough about Thursday's study results to know the true answer. Sage doesn't intend to develop SAGE-547 any further in essential tremor. Instead, the company will likely turn to a similar but oral compound, SAGE-217, which will be ready for human, healthy volunteer safety studies later this year.
Sage is developing SAGE-547 as a treatment for a severe form of epilepsy known as refractory status epilepticus. A phase III study is underway. Earlier this year, Sage also reported on a small, proof-of-concept study in which an injection of SAGE-547 eliminated severe postpartum depression in four women.
In the study reported Thursday, 25 patients with moderate-to-severe essential tremor were randomized to treatment with an injection of SAGE-547 or a placebo injection. Doctors and patients were blinded to the treatments.
The amplitude and frequency of tremor motion was measured using an accelerometer device attached to the patients' arms. In a test of upper limb kinetic tremor (patients were asked to touch their finger to their nose), the SAGE-547 injection resulted in a statistically significant reduction in tremors compared to placebo after 12 hours.
A composite assessment of various arm movements, also measured with an accelerometer, showed after 12 hours a 33% response rate for patients treated with SAGE-547 compared to 16% for placebo. The difference, however, was not statistically significant.
Likewise, a subjective clinician rating scale of tremor reduction trended in favor of SAGE-547 over placebo but was also not statistically significant.
The highest blood levels of SAGE-547 matched the drug's peak therapeutic activity over the course of the short study.
In a second stage of the study, 17 of the 25 essential tremor patients were treated with a dose of SAGE-547 twice as high as what was used in stage one. The response rate to SAGE-547 was higher although there was no placebo arm for a comparison. One patient discontinued due to low blood pressure and sleepiness. Other patients reported fatigue, sleepiness and dizziness.
Sage shares closed Wednesday at $54.77, ahead of the essential tremor study results.