Shares of Juno Therapeutics plunged more than 27% Friday, a day after halting a midstage study on a potential leukemia treatment following two patient deaths.
The development-stage biotechnology company is working on JCAR015 as a treatment for a type of leukemia. It is the company's most advanced drug candidate and therefore the most visible indicator of progress for investors.
The Seattle-based company said Thursday that the study has been put on hold after it added the chemotherapy drug fludarabine to the regimen. It has proposed continuing the study without fludarabine.
Midstage studies focus on a potential drug's effectiveness and are a key step in the development and eventual approval process.
Shares of Juno Therapeutics Inc. dropped $11.15, or 27.3%, to $29.66 in morning trading. Its shares have fallen almost 40% over the past year.