GlaxoSmithKline’s Tyverb (lapatinib) in combination with Roche's Xeloda (capectabine) delays progression of metastatic breast cancer and may prevent it spreading to the brain, according to a study reported at the European Cancer Conference in Barcelona.

The late-stage, company-backed trial evaluated Tyverb with Xeloda, versus Xeloda alone, for patients with advanced metastatic HER2-positive breast cancer whose disease had progressed following treatment with Roche/Genentech’s Herceptin (trastuzumab) and other cancer therapies.

The study found that when patients were treated with both Tyverb and Xeloda, disease progression was delayed to 27 weeks, from 19 weeks for patients taking Xeloda alone.

There was also a significant reduction in the number of patients who went on to develop brain cancer; only 2% among patients treated with the combination treatment compared with 11% of those taking just Xeloda.

A challenge to top-selling Herceptin

Brain cancer develops in up to a third of women with this form of breast cancer and prognosis is poor, with only around 20% of patients surviving after one year. Tyverb, sold as Tykerb in the US, is a kinase inhibitor that works through multiple pathways to deprive tumour cells of signals needed to grow. Unlike the monoclonal antibody Herceptin, which is a large protein molecule that targets the part of the HER2 protein on the outside of the cell, Tyverb is able to enter the cell and block the function of this and other proteins. This has led some analysts to believe that Tyverb has the potential to become a blockbuster product in the next decade and challenge Herceptin for the top slot.

GlaxoSmithKline also announced results of another study combining Tyverb with chemotherapy paclitaxel, in which patients on the dual therapy showed better response and improved survival rates compared with patients taking paclitaxel alone.

John Crown, lead researcher for one of the trials and a consultant medical oncologist at St Vincent’s University in Dublin, said: “These data demonstrate how lapatinib in combination with certain standard chemotherapies may benefit patients in different clinical setting, including first-line treatment.”