Roche announced on Friday that it was halting the clinical studies of drugs for breast cancer and Alzheimer's disease since they failed to provide significant improvement to patients.

The Swiss drugmaker explained that it chose to end the development of the Alzheimer's drug, gantenerumab, since it wasn't that effective. The drug for breast cancer, Kadycla, also failed to provide significant results showing that it can replace Herceptin, an approved drug used to treat patients with breast cancer and stomach cancer.

"We had hoped to show improvement in progression-free survival without the use of traditional chemotherapy," said Sandra Horning, Roche's chief medical officer. "While Marianne didn't achieve this result, we will continue to study these medicines, as well as investigational treatments for other types of breast cancer, with the goal of improving outcomes for patients."

Kadycla is a drug that can be used alone or in combination with Perjeta and Herceptin. The late-stage clinical trial result showed that it wasn't better than Herceptin. Researchers expected that Kadycla would improve the survival rate of breast cancer patients without using chemotherapy that the drug failed to deliver.

"Kadycla is important in Roche's life-cycle management of its breast cancer franchise because it should take over from Herceptin as a gold standard treatment," Chi Tran-Brändli, an analyst at J. Safra Sarasin, told the Wall Street Journal.

Investors expressed their disappointment of the Alzheimer's drug which could be the first treatment for the neurological disorder if it happened to be successful. But the setback for Kadycla is much bigger; Kepler analyst Fabian Wenner said that the company has forecasted that the breast cancer drug could generate as much as $2.56 billion in 2020, according to Reuters.

The announcement caused Roche's shares to plummet by 5.7 percent, the highest drop in the company's stocks in five years.