GSK's Tykerb misses breast cancer trial endpoint

GlaxoSmithKline's (GSK) Tykerb was unable to conclusively show an increase disease-free survival (DFS) in a phase III trial intended to support its use in early-stage HER2-positive breast cancer patients.

The results of the TEACH trial were presented last week at the San Antonio Breast Cancer Symposium in the US and revealed that while Tykerb/Tyverb (lapatinib) was able to show a trend towards disease-free survival in  the delayed adjuvant setting following initial surgery or chemotherapy.

After a median follow-up of four years, DFS events occurred in 13 per cent of patients in the lapatinib arm and 17 per cent on placebo. The trial specifically excluded patients who had been treated with Roche's rival drug Herceptin (trastuzumab).

"We are disappointed that the improvement in disease-free survival with lapatinib monotherapy in TEACH did not reach statistical significance," commented Rafael Amado, senior vice president, oncology development, at GSK.

However, "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," he added.

Tykerb was approved for the latter indication in 2007, and generated $360m in sales for GSK in 2010. GSK has however struggled to extend the indications for the product to fulfil its once-touted blockbuster status. In comparison, Herceptin revenues reached $6.8bn last year.

In September, the company decided to drop the monotherapy arm of the ALTTO study in early-stage breast cancer after concluding that Tykerb was unlikely to be as effective as Herceptin when used on its own.

The study is also looking at the two drugs in combination and given sequentially, and will continue to follow-up patients on these regimens, but at best will support use of Tykerb in combination with Herceptin in the adjuvant setting.

Tykerb is also in phase III testing in gastric cancer and squamous cell carcinoma of the head and neck.