Pharmaceutical company GlaxoSmithKline said Friday it stopped a clinical trial for breast cancer patients treated with its drug Tykerb alone.

GlaxoSmithKline said the trial - part of a 4 arm study - was unlikely to meet the pre-specified criteria to demonstrate that it was superior to Roche's drug Herceptin with respect to disease-free survival.

"Consequent to this finding, patients assigned to the lapatinib alone arm of the trial will discontinue lapatinib (Tykerb) and discuss treatment options with their study physician," the company said in a press release Friday.

The other three arms of the study will continue without modification, the pharmaceutical firm said.

Tykerb and Herceptin are designed for women with an agressive form of breast cancer known as HER2-positive. The drugs are administered alongside standard chemotherapy.