Amgen completes PhIII trifecta as AMG416 goes head-to-head with Sensipar

Amgen R&D chief Sean Harper

Amgen hit the trifecta with a successful conclusion to its third, and last, Phase III study of AMG416, a new drug for secondary hyperparathyroidism which handily beat out its in-house rival Sensipar in a head-to-head study.

The Big Biotech ($AMGN) says that AMG416 hit the primary endpoint: noninferiority to Sensipar in achieving a greater than 30% reduction from baseline in "mean pre-dialysis serum intact parathyroid hormone (PTH) levels during the Efficacy Assessment Phase, defined as the period between weeks 20 and 27." Both secondary endpoints fell easily to AMG416, with 52.4% in the drug arm seeing a greater than 50% drop in PTH compared to 40.2% in the Sensipar arm. Meanwhile 68.2% in the experimental drug group saw a greater than 30% reduction compared to 57.7% in the control arm.

Investigators for Amgen already had no problem demonstrating that AMG416 could easily beat out a placebo in two earlier late-stage trials. Amgen acquired KAI and this drug in a $315 million acquisition just after Roger Perlmutter's exit as head of R&D and Sean Harper's promotion in early 2012. 

Secondary hyperparathyroidism is often found among dialysis patients whose parathyroid glands kick into action as kidney function declines, generating dangerous hormone levels as the body tries to maintain the proper level of calcium and phosphorus. Amgen sells Sensipar, an oral drug, for the condition, but believes it can open up a significant new market for this IV formulation that can be delivered during hemodialysis. A study for Sensipar (cinacalcet) in children was halted early last year following the death of one of the test subjects.

Analysts give this new drug a good shot at matching Sensipar sales of more than $1 billion as generic competition threatens that market. But the biotech won't say just what it's plans are for filing on an approval.

"While we are encouraged by the emerging efficacy and safety profile of AMG 416, it is too early to speculate on our regulatory filing," a spokesperson tells FierceBiotech. "We will evaluate the Phase III data in its entirety and disclose next steps, including those with regulatory, as appropriate."

AMG416 isn't without side effects. Adverse events like a drop in blood calcium and nausea have registered higher in the drug arm than in the placebo group. But the placebo arm nevertheless experienced a higher rate of serious adverse events. And the safety profile looked similar to Sensipar in this last study.

"The management of this disease in patients with chronic kidney disease is a complex process, and at Amgen, we are committed to building upon our leadership in nephrology to provide patients with an innovative therapy that can be administered intravenously along with hemodialysis," says Harper in a statement. Amgen is also hustling along a PCSK9 drug, another late-stage effort that has been consuming a considerable amount of time and money as the company restructures its R&D operation.

- here's the release

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