Drug Development

That big new hyperparathyroidism drug from Amgen? The FDA rejected it

According to regular updates from Amgen over the past two years, investigators marched through a trio of late-stage studies for etelcalcetide (AMG416) with nothing but good things to report. The drug scored outstanding data for secondary hyperparathyroidism (SHPT), a disease that affects chronic kidney disease patients on hemodialyis.

And this evening Amgen reported that the drug was rejected by the FDA. The news came in a terse statement, without a hint about what the agency objected to.

The commercial name for this drug is Parsabiv. And here’s what Amgen — a big biotech not known for explaining distasteful things — had to say about it:

Amgen is reviewing the Complete Response Letter, and we anticipate a post-action meeting with the FDA later this year to discuss the Complete Response. The Complete Response Letter does not impact our regulatory submissions in other regions.

Amgen tested the drug in more than a thousand patients, reportedly meeting its primary endpoints by slashing dangerously high parathyroid hormone levels. In one study 74.7% of subjects on the drug hit its target, compared to just 8.9% in the placebo arm. In another Phase III trial the new drug outperformed Amgen’s blockbuster drug Sensipar, which earned $1.4 billion.

This was one of Amgen’s top Phase III efforts in the pipeline. It scored a success on its PCSK9 cholesterol drug, but it’s been a disappointment in its early days on the market.

Brian Skorney, Baird analyst

Brian Skorney, Baird analyst

Baird’s Brian Skorney noted the absence of any explanation from Amgen, and then offered his opinion that the agency might have been put off by safety issues. His comment:

In the head-to-head study, Sensipar and Parsabiv looked similar, with Parsabiv showing higher rates of treatment-emergent AEs (93% vs. 90%) overall, with a slightly lower rate of serious adverse events (25% vs. 27%). Specifically, Parsabiv showed higher incidence of hypocalcemia (5% vs. 2.3%), cardiac failure (3% vs. 0.6%), and fatal adverse events (2.7% vs. 1.8%). It remains unclear whether or not these differences factored into the FDA’s decision. It is possible that the modest increase in these adverse events outweighed the benefits provided on secondary endpoints and in the differing administration, in the FDA’s opinion. It’s also possible that this is just a minor CMC issue and can be quickly resolved.

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Sr. Manager, Regulatory Affairs, CMC
CytomX Therapeutics San Francisco, CA
Marketing Associate - Demand Generation
Catalytic Data Science Charleston, SC
Associate Principal, Life Sciences Partnerships
Flatiron Health New York City or San Francisco

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