UPDATE 3-Annovis tumbles as Alzheimer's treatment misses in mid-stage study

(Adds analyst comments in paragraph 5 and 8, background in paragraph 6)

By Pratik Jain and Christy Santhosh

April 29 (Reuters) - Annovis Bio's on Monday reported data that showed its Alzheimer's disease drug failed to show statistical significance in meeting the goals of a mid-stage trial sending its shares tumbling as much as 60%.

The trial tested the drug buntanetap in patients with mild-to-moderate Alzheimer's disease (AD) along two scales assessing cognition and cognitive dysfunction.

In a press release, the company said a "post-hoc" analysis of the trial data had shown statistically significant results in improving cognition function scores along an Alzheimer's disease scale in a subgroup of patients who had mild disease and who tested positive for certain disease biomarkers.

However, the company only included a sub-group of patients in its analysis, around 90 of the planned 325 patients, which was not the pre-specified criteria of the study.

"Many investors anticipated the data for the classic AD biomarker, amyloid beta", brokerage Ladenburg Thalmann analyst Aydin Huseynov said, adding, "investors perhaps wanted to see the data from all 325 patients..."

Amyloid beta is a toxic protein that accumulates in the brains of people with Alzheimer's.

The company said it believed the drug could "give patients both symptomatic and disease-modifying benefits," and plans to conduct a late-stage trial over 18 months on patients with early Alzheimer's disease.

Huseynov, however, added that, "with the statistical significance of the data and the dose-dependent responses, we think this angle of the readout makes sense".

The drug also failed to show statistical significance on another co-primary goal of the study which measured cognition along a scale known as ADCS-CGIC, which relies on both direct examination of patients by doctors and interview of care providers.

It also failed to show a statistical improvement in a secondary goal of the trial.

Shares of Annovis were halted several times in Monday's session for volatility. (Reporting by Christy Santhosh, Bhanvi Satija and Pratik Jain in Bengaluru; Editing by Vijay Kishore and Tasim Zahid)