Amgen's viral cancer vaccine misses its survival goal in melanoma PhIII

Amgen R&D chief Sean Harper

After a string of promising late-stage results, Amgen's ($AMGN) cancer-fighting viral vaccine failed to extend patients' lives at a statistically significant rate, missing a secondary endpoint and marking the first blemish on the biotech's top cancer prospect.

In top-line results from an analysis of its Phase III program, Amgen said talimogene laherparepvec (nicknamed T-Vec) hit its primary endpoint of durable response in patients with metastatic melanoma but missed its second goal of boosting overall survival. But it was close, the company notes, pointing to a "trend" toward statistical significance with a p value of 0.051.

The slip follows months of positive indications from T-Vec's ongoing Phase III program, as the oncolytic virus proved it could shrink tumors, keep them from regrowing and, in early results unveiled in November, improve median survival. But amid all the pomp and circumstance over interim data, market watchers have been holding out for the all-important mature OS results, and T-Vec's late-stage miss comes as a disappointment for the much-watched program. ISI analyst Mark Schoenebaum pegs the drug's 2019 sales at around $240 million but said in an investor note that the consensus may come down in light of the latest data.

But Amgen R&D Chief Sean Harper said the company is still confident in its virus.

"We missed statistical significance on the secondary endpoint of overall survival, but the strong trend in survival benefit supports further research of talimogene laherparepvec to better understand its role in melanoma, both as a single-agent and in combination with other therapies," Harper said in a statement.

And that latter option may be T-Vec's best bet. Amgen has already launched a combo study pairing the virus with Bristol-Myers Squibb's ($BMY) top-selling Yervoy, and the company has teamed up with Merck ($MRK) to see how well its drug can complement MK-3475, a PD-1 checkpoint inhibitor. If T-Vec can prove itself a worthy co-star in a future cancer-fighting cocktail, the virus' OS troubles may not loom so large in the end.

Amgen picked up T-Vec in its $1 billion deal for 2009 Fierce 15 honoree BioVex. The drug, a re-engineered herpes simplex virus, is designed to replicate itself within tumor cells until they burst, all the while stimulating an immune response against the cancer cells.

- read Amgen's statement

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