GSK’s Combination Breast Cancer Treatment Fails to Meet Primary Endpoint

June 2, 2014

GlaxoSmithKline has reported that its Phase III trial of two anti-HER2 agents, Tykerb (lapatinib) and trastuzumab, as a treatment for patients with HER2 positive primary breast cancer, failed to meet a primary endpoint of improved disease free survival (DFS) compared with using trastuzumab alone.

The results were announced Sunday at the 50th Annual Meeting of the American Society of Clinical Oncology (ASCO) in Chicago, Illinois.

In the ALTTO study of more than 8,000 women with breast cancer, 88 percent of patients treated with lapatinib plus trastuzumab lived without their disease returning for four years, while 86 percent in the trastuzumab-only arm had the same rate. The two percent difference was not considered statistically significant.

The company said that the safety profile was consistent with the study drugs’ established safety profile, with no new safety signals observed.

"While it is disappointing that ALTTO did not meet its primary endpoint, we now have a tremendous amount of information that will help to further our knowledge of the biology of this disease and inform future studies in HER2-positive breast cancer in the adjuvant setting," Rafael Amado, GSK's vice president of oncology R&D, said in a statement.

However, Tykerb will soon be Norvartis’ problem. GSK sends its oncology assets to the Swiss drugmaker as part of a blockbuster swap the companies announced in April. The deal is expected to close in the first half of 2015. — Kellen Owings

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