Biogen's stock took a dive on Thursday after it announced the end of trials for Aducanumab, a drug that is supposed to help treat patients with Alzheimer's disease. The shares plunged to more than 29 percent, posting its worst day since 2005.

As noted by CNBC News, Biogen is one of the biggest biotechs in the world and its market value was listed at US$63 billion. The company along with Eisia, its Japanese partner in the project, decided to halt the trial after the data analysis team determined that the trials will not meet their primary deadline and immediately, both firms lost money after their shares plummeted.

Biogen and Eisai stocks are said to have hit its 52-week low levels on March 21 and the former's market cap today post the disappointing news. Biogen's market cap dipped to a staggering US$18 billion.

Biogen is the latest pharmaceutical company to stop the research on treatment for Alzheimer's. In the past, Pfizer, Merck, Eli Lilly, Pfizer and AstraZeneca have abandoned their drug trials on the disease that causes mental deterioration especially among the elderly.

At any rate, CNN reported that Aducanumab was thought to be Biogen's next blockbuster medicine as the previous trials yielded successful results. However, it was said that treating Alzheimer's disease is proving to be tenuous.

Commenting on the end of the trials for the Alzheimer's drug, Biogen CEO Michel Vounatsos said, "This disappointing news confirms the complexity of treating Alzheimer's disease and the need to further advance knowledge in neuroscience."

He added, "We are incredibly grateful to all the Alzheimer's disease patients, their families and the investigators who participated in the trials and contributed greatly to this research."

It was learned that the Phase 3 of the Alzheimer's drug trial includes the what they called the "ENGAGE and EMERGE" trials. This will determine if a monthly dosage of Aducanumab can effectively slow down the cognitive and functional impairment in patients. But it was said that this has issues too as it does not have any safety concerns.

Finally, with Biogen's failure to proceed with Aducanumab testings, it has to come with new schemes to continue the research and bring an effective drug out there. This will be a big help to those suffering from the dreaded neurodegenerative disease so treatment is needed to be found now.