GSK misses survival endpoint with Tykerb-Herceptin pairing

CHICAGO--When it comes to improving disease-free survival in HER2-positive early breast cancer patients, two isn't better than one, GlaxoSmithKline ($GSK) found--at least, not when those two are Tykerb and Roche ($RHHBY) cancer giant Herceptin. As Glaxo announced at ASCO on Sunday, a Phase III study of the pair missed that primary endpoint, failing to outdo Herceptin on its own.

GSK SVP of Oncology R&D Dr. Rafael Amado

In the 8,000-plus-patient study, dubbed ALTTO, 86% of women treated with Herceptin as an adjuvant therapy lived for four years without their cancer returning and 88% of women receiving a Herceptin-Tykerb combo reached that mark--a non-statistically significant difference. In women receiving Herceptin followed by Tykerb, the 4-year disease-free survival rate came out to 87%.

"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," Dr. Rafael Amado, GSK's SVP of oncology R&D, said in a statement.

And analysis of these data will be ongoing, GSK Oncology VP Alison Armour told FiercePharma. "This will be one of the most important trials we've ever conducted," she said in an interview.

Glaxo has been looking for ways to expand sales of Tykerb, which sank 13% to £207 million last year thanks to increased competition. A 9% slide in the company's Emerging Markets and Asia Pacific region helped trigger that drop; patent woes over the drug in India haven't helped matters for the pharma giant, with the country's Intellectual Property Appellate Board pulling GSK's IP shield in August.

But this isn't the first time those efforts have missed the mark. After pairing Tykerb with Herceptin, last year's No. 3 best-selling cancer drug, for women with advanced breast cancer, in mid-2012 Glaxo yanked its FDA application on regulatory concerns with the control arm in the submission's pivotal trial.

Before too long, however, Tykerb will be Novartis' ($NVS) to deal with. As part of a blockbuster asset swap the companies announced in April, Glaxo will send its oncology assets over to the Swiss pharma, with their deals expected to close in the first half of 2015.

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