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Amgen's EPO Drugs Dodge a Bullet as Hematide Stumbles, but the Big Biotech's Trials Aren't Over

By Trista Morrison

Updated on: June 22, 2010 / 9:30 AM EDT / MoneyWatch

Amgen's (AMGN) multi-billion-dollar anemia drugs dodged a bullet yesterday when rival Affymax (AFFY) and Takeda reported mixed data from four Phase III trials of their drug Hematide. But Amgen isn't totally out of the woods just yet.

As much as Amgen's bone loss drug Prolia (denosumab) has commanded the spotlight of late, anemia drugs Epogen (epoetin alfa) and Aranesp (darbepoetin alfa) still play a huge role in Amgen's drug portfolio. Despite being battered by safety-driven regulatory and reimbursement issues, the anemia drugs brought in a combined $5.2 billion last year. For reference, analysts have pegged Prolia's recent osteoporosis approval as worth about $1 billion annually, though future label expansions in cancer might boost that figure to $4 billion.

So any competition Hematide might offer to Epogen and Aranesp has to be taken seriously. And most analysts thought Affymax's drug would be a strong contender. It's a synthetic small peptide -- a small strand of protein -- rather than a full-on protein like Amgen's drugs, which many thought would focus its activity in the body, possibly leading to more reliable control of blood-oxygen levels and fewer safety problems.

What went wrong? Technically all four Phase III Hematide trials met their endpoint of a noninferior change in hemoglobin compared to Amgen's drugs. The combined trials also met their safety endpoint of noninferiority with regard to cardiovascular side effects.

But a deeper dive into the data proved less flattering. A subgroup analysis of anemia patients not yet on dialysis showed more cardiovascular side effects with Hematide. In one trial, patients on Hematide needed more blood transfusions, and in another trial, the Hematide group had less success in reaching hemoglobin targets.

Affymax couldn't yet explain why its improved anemia drug didn't seem to show much of an improvement. The company suggested that the hemoglobin glitch wasn't clinically relevant and that the blood transfusion data might have been influenced by investigator bias. Regardless, Amgen investors praised their good luck today, while Affymax investors sent their company's stock plunging 69 percent.

But Hematide is by no means dead. Expectations that the drug would blow Amgen's products out of the water were clearly too high, but Hematide did meet its endpoints, and it does offer less frequent dosing. The trick will be getting it past a safety-conscious FDA that has already taken a black-eye over side effects linked to anemia drugs.

One approach may be to drop the pre-dialysis group and focus on approval for dialysis patients, who make up the larger portion of the market anyway. But Affymax has indicated it isn't throwing in the towel on either indication just yet, so Amgen might want to hold those champagne bottles in reserve and see how this plays out.

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New and Improved photo by Flickr user ckittel, CC.