Merck and Endocyte said Friday that they are stopping a clinical trial of an experimental cancer drug, sending Endocyte shares plunging.
The companies said the drug vintafolide didn't slow the progress of ovarian cancer. The trial compared a combination of vintafolide and the chemotherapy drug doxorubicin to doxorubicin and a placebo, and it was designed to test whether patients who took vintafolide lived longer before the resumption of disease progression or deaths.
The patients in the study had ovarian cancer and had not been helped by platinum-based chemotherapy.
The companies are ending the trial based on advice from an independent committee that reviewed data from the study.
Endocyte Inc. shares plunged $10.77, or 62 percent, to $6.61.
Vintafolide, or Vynfinit, is designed to target a receptor that appears on cancer cells but doesn't exist on most other cells. In March European Union regulator said vintafolide should be approved as a treatment for ovarian cancer, and Endocyte said the drug helped slow the progression of lung cancer in a midstage trial. Endocyte shares peaked at $33.70 that month.
In early April, Endocyte raised $101.8 million from a stock offering. Stock offerings often reduce a company's share price because they put more shares on the market.
Merck & Co. shares lost $1.60, or 2.7 percent, to $58.02.