US-based biopharmaceutical company Neurotrope has reported that the confirmatory Phase II clinical trial of Bryostatin-1 failed to meet the primary endpoint in patients with moderate to severe Alzheimer’s disease (AD).

Bryostatin-1 works by activating protein kinase C (PKCϵ), leading to the stimulation of synaptic growth factors and amyloid-β degrading enzymes, along with prevention of transformation of tau into neurofibrillary tangles.

The Phase II trial was conducted to evaluate the safety and efficacy of Bryostatin-1 to treat cognitive deficits in moderate to severe AD patients. It involved seven doses of 120μg Bryostatin-1 or placebo over 12 weeks.

Change in the Severe Impairment Battery (SIB) total score from baseline to week 13 was measured as the trial’s primary efficacy endpoint. Its secondary endpoints included repeated SIB changes between baseline and weeks five, nine, 13 and 15.

Bryostatin-1 did not reach statistical significance on the primary endpoint, with 1.3 points and 2.1 points of SIB total score for Bryostatin-1 and placebo, respectively.

In addition, a statistically significant difference was not achieved on the secondary endpoints.

Neurotrope CEO Charles Ryan said: “We are disappointed in the top-line results from the confirmatory Phase II study. Having just received the data, we are conducting a full review to determine potential next steps and will provide an update of our plans when appropriate.”

In a separate development, UK-based Axon Neuroscience announced positive data from the Phase II trial of vaccine AADvac1 designed to slow Alzheimer’s progression.

AADvac1 leverages the patient’s immune system to trigger the generation of antibodies that selectively target unhealthy tau.

Conducted in 196 mild Alzheimer’s patients, Axon’s Phase II ADAMANT trial demonstrated antibodies production in 98.2% of the subjects administered with the vaccine.

The vaccine was also found to be safe and well-tolerated.