PhIII judgment day looms for GlaxoSmithKline's heart drug darapladib

GlaxoSmithKline ($GSK) has racked up a slate of drug approvals this year, an impressive accomplishment for a company that had to endure a lengthy fallow period in R&D after it reorganized its extensive research operations. But its regulatory wins never quite made up for the fact that the pharma giant hasn't been able to pull off any big coups in the clinic with pioneering therapies.

GSK, though, hopes to answer its critics on the innovation front soon with a readout from the first of two big late-stage studies of darapladib, the heart drug hopeful that the company in-licensed from Human Genome Sciences. GSK bought out HGS, and all rights to darapladib, in a $3 billion buyout. The drug has been tapped by GSK R&D chief Moncef Slaoui as one of its two top innovative drugs in the pipeline, promising major gains for patients with coronary disease. His other top prospect on the innovation front: MAGE-A3, a therapeutic cancer vaccine which subsequently failed its first late-stage test.

As Reuters' Ben Hirschler notes in his preview today, the first Phase III--the 16,000-patient STABILITY study--has been completed. That trial is expected to deliver results soon on whether the drug lowered the risk of heart attack or stroke for coronary disease patients. The second study, scheduled to wrap next March, recruited 13,000 patients to see if it could prevent a second heart attack.

The drug inhibits the Lp-PLA2 enzyme, which should help reduce the development of arterial plaque. But this is a field that has seen numerous expensive setbacks, and Reuters cites two analysts projecting only a 10% and 30% chance of success. A win here could be worth $10 billion, reports Hirschler, citing a chart-topping figure that represents the holy grail of megablockbuster development. But the hurdles here--even if the Phase III studies are successful--are enormous.

In the company's most recent quarterly call with analysts, CEO Andrew Witty noted that all big pharma companies need a pipeline balanced between high-risk breakthroughs and low-risk drug projects.

GSK has scored on the low-risk, me-too side of the R&D equation. Darapladib will go a long way to determining whether the company can also deliver big innovations. 

- here's the Reuters story

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