Biogen has today revealed surprise plans to seek US regulatory approval for its Alzheimer's treatment aducanumab.

The company said that new analysis of clinical trials showed promise, just months after it had shelved two studies. 

The drugmaker's shares has been under pressure from investors to beef up its drug development pipeline .

It also reported a better-than-expected third quarter profit, soared 35%, more than erasing all of its losses so far this year. 

Biogen and partner Eisai had in March decided to end two late-stage trials of aducanumab based on a so-called "futility analysis" of data, which revealed the trials had little hope of succeeding. 

The failure of treatment, which was widely expected to be the Biogen's next blockbuster treatment, spurred demands on Wall Street for it to spend more on product acquisitions at a time when its peers have splurged out billions of dollars on deals. 

There are no current approved therapies for reversing the decline of Alzheimer's and any successful new treatment is likely to garner billions in sales. 

Alzheimer's makes up 60-70% of an estimated 50 million cases of dementia globally. 

The company said more data became available after the two studies that were discontinued in March, resulting in a larger dataset and a new analysis showed a positive outcome for the trial. 

Patients who received aducanumab experienced significant benefits on measures of cognition and function such as memory, orientation and language, Biogen said. 

Based on discussions with the FDA, Biogen said it plans to submit a marketing application for aducanumab in early 2020.

Shares of Biogen, which had lost 25.7% this year as of yesterday's close, were up almost $100 in value at $323 in pre-market trade.

They fell back below $300 as the trading day progressed, representing an intraday jump of almost 30%.

The company's third-quarter results saw profit rise 7.1%, boosted by higher demand for rare muscle disease drug, Spinraza. 

Net income attributable to the company rose to $1.55 billion, or $8.39 per share, in the quarter ended September 30, from $1.44 billion, or $7.15 per share, a year earlier. 

Total revenue for the three month period rose nearly 5% to $3.60 billion.