Setting aside its problems with Avandia, GlaxoSmithKline has been imparting some good news about its new breast cancer drug Tykerb at the American Society of Clinical Oncology meeting in Chicago.

The UK drugs giant presented data which revealed that Tykerb (lapatinib), in combination with paclitaxel, increased progression-free survival in the first-line treatment of patients with metastatic HER2-positive breast cancer, compared with chemotherapy alone.

In a Phase III trial of 580 patients, 91 were retrospectively identified as having HER2-positive disease and in this sub-group, the median progression-free survival was 7.9 months for patients who received the Tykerb combination, compared with 5.2 months in those who received paclitaxel alone. Additionally, the findings showed that 60% of patients who were administered Tykerb plus paclitaxel experienced a complete or partial response, compared to 36% on chemotherapy alone.

Angelo Di Leo, director of the medical oncology unit at the Hospital of Prato in Italy, and lead investigator on the trial, noted that the results “have the potential to directly impact clinical practice and may benefit patients in the first-line treatment setting”. He added that Tykerb in combination with paclitaxel “is a step in the right direction as the oncology community explores potential combination therapies to individualise treatment for breast cancer patients.”

Tykerb reduces brain tumour lesions

GSK also presented data from a 241-patient Phase II study of Tykerb in patients with brain metastases associated with breast cancer, which showed that 7% treated with lapatinib as monotherapy experienced a partial response, defined as a minimum 50% reduction in brain lesions without tumour progression elsewhere, while 19% experienced a 20% reduction in the size of the tumour. An additional 102 patients (42%) achieved stable disease for at least eight weeks, while 22% of all patients had no disease progression within the first six months on Tykerb monotherapy.

Lead investigator Nancy Lin of Harvard Medical School said these data suggest that “Tykerb may cross a compromised blood brain barrier,” and this would give it an advantage over Roche’s blockbuster and breast cancer standard treatment Herceptin (trastuzumab) which cannot, as the molecule is too big. Tykerb is currently approved in the USA for the treatment of patients with advanced HER2-positive breast cancer who have failed on prior therapy and is under review in Europe.