GSK breast cancer drug fails to work alone

 GlaxoSmithKline’s breast cancer drug Tyverb (lapatinib) has failed to show a significant increase in disease-free survival (DFS) when used alone in patients with early-stage HER2-positive breast cancer.

The results of the TEACH phase III clinical trial mean that Tyverb (known as Tykerb in the US) is unlikely to succeed as a monotherapy in this indication, though it will continue to be used in combination therapy.

The TEACH trial established that 13% of patients treated with Tyverb following initial surgery or chemotherapy for breast cancer achieved DFS after four years, compared to 17% on placebo.

The trial did not compare Tyverb with Roche’s breast cancer drug Herceptin (trastuzumab). The two drugs were approved by the FDA for use in combination in 2007, and in that indication earned GSK $360 million in 2010.

However, whereas Herceptin has proved successful as a monotherapy, Tyverb has not. In September, GSK abandoned the monotherapy arm of another trial (ALTTO) after concluding that Tyverb was less effective in treating early-stage breast cancer than Herceptin alone.

The TEACH trial is still expected to support the use of Tyverb in combination with Herceptin.

“We are disappointed that the improvement in disease-free survival with lapatinib monotherapy in TEACH did not reach statistical significance,” said Rafael Amado, Senior VP of Oncology Development at GSK.

“Lapatinib combination therapy remains an important treatment option for patients with metastatic HER2-positive breast cancer whose disease has progressed on treatment with trastuzumab-based regimens.”