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In big setback, GlaxoSmithKline's cancer immunotherapy MAGE-A3 flunks PhIII goal

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GlaxoSmithKline R&D chief Moncef Slauoi

GlaxoSmithKline ($GSK) experienced a major R&D setback today, reporting that its targeted cancer immunotherapy MAGE-A3 failed its first co-primary endpoint in a Phase III study for melanoma, failing to beat out a placebo in spurring disease-free survival.

GSK investigators will now continue the study until they can nail down the second primary endpoint, exploring DFS in a genetically defined subpopulation. That data should follow in 2015. The DERMA study was created to assess the efficacy and safety of MAGE-A3 in Stage IIIB/C melanoma patients with macroscopic nodal disease whose tumors expressed the MAGE-A3 gene and had their tumors removed surgically.

The Phase III failure blitzed shares of Lexington, MA-based Agenus ($AGEN), which provided an adjuvant used in GSK's immunotherapy. In its release, Agenus noted that a positive outcome on the second co-primary endpoint could set up a regulatory filing for approval. But investors weren't in an optimistic frame of mind this morning. The biotech's shares plunged and were down 28% in early trading.

After reorganizing its R&D operations about four years ago, the pharma giant has had a string of drug approvals to boast of this year. But even its R&D chief Moncef Slaoui conceded that these new approvals were arriving for second-line therapies that faced a competitive struggle in carving out a significant share of their intended market. MAGE-A3 and the heart drug darapladib, though, were singled out as the company's crown jewels in R&D, true "breakthroughs" that have first-line potential.

The news dinged the big company's share price today and caused at least one analyst to shave his price target.

The next hurdle for MAGE-3 will come with data from an ongoing Phase III study in non-small cell lung cancer. That announcement should come in the first half of 2014. There was no data in today's release, standard operating procedure for developers who typically wait for a big scientific conference to release the details.

"We want to thank all patients, their families and healthcare workers for their involvement in the trial and we remain committed to identifying a patient sub-population who may benefit from this investigational treatment," said Vincent Brichard, the head of immunotherapeutics at GSK Vaccines, in a statement.

Slaoui may have been pumped about MAGE-A3's potential, but Ben Hirschler at Reuters notes that a number of analysts have been skeptical about its chances.

"This asset was widely regarded as a 'wild card' by the market," wrote Alistair Campbell of Berenberg Bank. "While there had been some hope that this approach might work, the result is not a surprise." Chances of a positive outcome in lung cancer, he added, are slim.

- here's the release
- here's the report from The Guardian
- here's the report from Reuters

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