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Amgen's viral cancer vaccine T-Vec tackles melanoma tumors in PhIII

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Amgen R&D chief Sean Harper

Amgen ($AMGN) has stepped up with a new round of late-stage data supporting its cancer-fighting viral vaccine talimogene laherparepvec, better known as T-Vec. In a retrospective analysis of a Phase III melanoma trial investigators found that about two-thirds of the tumors injected with T-Vec shrank 50% or more. And the same effect was seen in about a third of all uninjected tumors in the skin and lymph nodes, providing an indication that the treatment is triggering the desired immune system effect.

Of the 64% of injected tumors which shrank, half registered a complete response, disappearing from view. The company is wrapping pivotal work now to determine if those tumor responses definitively translate into a longer life for patients, which will determine the fate of this therapy.

While cancer vaccines have had a poor track record in the clinic in recent years, Amgen has tapped T-Vec as one of the big biotech's top prospects. The engineered virus is designed to specifically replicate in cancer cells, expressing the white blood cell growth factor GM-CSF to spur an immune system response. Amgen's then R&D chief Roger Perlmutter--now at Merck ($MRK)--acquired the program about three years ago, buying out BioVex in a $1 billion deal.

In this particular study, the investigators went back to look at about 4,000 tumor lesions in 295 patients who were injected with T-Vec. A quarter of those patients experienced serious adverse events, including disease progression, cellulitis and pyrexia.

This new analysis is built on a study that recently demonstrated a durable tumor response of at least 6 months in Phase III. And interim results from another study concluded that T-Vec patients had a median overall survival rate of 23.3 months compared to the 19-month average posted by patients treated only with GM-CSF. All that is helpful in building the case for T-Vec, but the big event that analysts are waiting for is the release of definitive survival data sometime in the next few months.

Amgen, though, isn't waiting for the survival data. The Big Biotech has already launched a combo study with Yervoy from Bristol-Myers Squibb ($BMY) and just signed on to collaborate with Perlmutter on a combo study with Merck's PD-1 cancer therapy MK-3475.

"These data add to the body of evidence supporting talimogene laherparepvec's local and distant effect, and its potential ability to stimulate a systemic anti-tumor immune response," said Sean Harper, Perlmutter's successor at Amgen. 

- here's the release from Amgen

Special Report: Top 10 experimental cancer drugs - 2013 - T-Vec

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