Amgen Inc. announced on Monday it has ended two clinical studies on an experimental cancer drug after a preliminary review showed increased deaths among one group of patients.

The Thousand Oaks biopharmaceutical company said that it would terminate studies on rilotumumab, a novel drug developed in-house that treats stomach cancer when used in combination with standard chemotherapy.

A review by a monitoring committee found an increase in the number of deaths for the group of patients using both rilotumumab and chemotherapy compared to the group receiving only chemotherapy.

Amgen is giving investigators guidance to wind down the Phase 3 studies and follow up with patients. Also, the company plans to publish results from one of the studies.

“While we are disappointed with these results, we will work with lead investigators to further analyze the data in order to help inform future research and therapies in this area,” said Dr. Sean Harper, executive vice president of research and development, in a statement.

Shares closed up $1.37, or a fraction of a percent, to $164.18 on the Nasdaq.