GlaxoSmithKline's drug Tykerb failed to hit its goal in a clinical trial testing its role in women with early breast cancer, dimming hopes for its use in this setting.
Britain's biggest drugmaker said results from a Phase III study of Tykerb given in the delayed adjuvant setting, following initial surgery or chemotherapy, did not reach statistical significance.
The findings from the so-called TEACH study were presented late on Thursday at the San Antonio Breast Cancer Symposium.
The disappointing outcome follows other poor results in previous adjuvant studies and analysts at Deutsche Bank said the data suggested substantial use of Tykerb in the adjuvant breast cancer setting was very unlikely.
Tykerb, a rival to Roche's Herceptin, is already approved in 107 countries for treating metastatic breast cancer, a later stage of the disease when cancer was spread around the body.
Shares in GSK were 0.9 percent lower at 8:55 a.m., slightly underperforming a 0.6 percent decline in the European sector.
(Reporting by Ben Hirschler, Editing by Mark Potter)