Biogen announced on Thursday that it would discontinue the phase-3 trials on aducanumab, a drug candidate for Alzheimer’s disease.

The biotech company said it would terminate the phase-3 ENGAGE and EMERGE trials that aimed to evaluate the efficacy and safety of aducanumab in patients with mild Alzheimer’s disease and cognitive impairment.

The company said it would also discontinue the phase-2 EVOLVE study of aducanumab, which was an extension of the phase-1b PRIME to evaluate the experimental drug’s safety.

Biogen plans to disclose the detailed outcomes of ENGAGE and EMERGE studies at an academic meeting in the future.

Knowledge gained from the failure of the two trials will help Biogen study the mechanism of dementia treatments targeting amyloid, the company said.

Biogen noted that there was no safety issue in the discontinued trials, leaving possibilities for aducanumab’s effect on dementia prevention.

“The decision was based on the data monitoring committee’s futility analysis that the trials would not reach their primary endpoint. It was not the issue of aducanumab’s safety,” Biogen said.

Major pharmaceuticals have developed dementia treatments based on the assumption that Alzheimer's was associated with the accumulation of beta-amyloid, and eliminating or suppressing it would treat or prevent Alzheimer’s.

Adubanumab is also a monoclonal antibody developed by eliminating beta-amyloid to inhibit the progression of Alzheimer's disease.

Global drugmakers such as Lilly have been developing treatments on such a hypothesis, but all have failed.

Lilly is conducting phase-2/3 trials to check if the combination of solanezumab and Roche's gantenerumab is effective in patients with Alzheimer’s with inherited mutations that cause its early onset.

MSD also tried to treat dementia by inhibiting the production of beta-amyloid with a β-secretase (BACE) inhibitor, verubecestat. However, its data monitoring committee concluded that the trial was invalid in early 2017. In February of that year, the company halted the study for early-stage Alzheimer’s patients.

Johnson and Johnson aimed to delay the cognitive decline in Alzheimer's patients through the BACE inhibitor atabecestat but gave up clinical trials in May last year due to hepatotoxic side effects.

The situation was not much different in the case of Roche’s monoclonal antibody crenezumab, as the phase-3 trial on crenezumab had to be scrapped in January due to its inefficacy.

On the news about Biogen’s termination of the trials on aducanumab, Samsung BioLogics shares fell on Friday. Samsung BioLogics, however, said the company suffered no damage.

Stock prices of the biosimilar maker went bearish from the start of the morning trading. As of 2:30 p.m. on Friday, Samsung Biologics shares dipped 2.73 percent to 339,000 won ($299.9) per share.

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