UPDATED: Affymax, Takeda pull Omontys after 3 deaths

Severe hypersensitivity reactions in Omontys patients prompted Affymax ($AFFY) and Takeda Pharmaceutical to recall all lots of the anemia drug, designed for use in dialysis patients. The FDA says it received reports of 19 serious reactions; three of those patients died.

The news eviscerated Affymax's share price, which plunged 85% Monday morning as stunned investors responded to the recall and the sudden change in fortunes. The plunge wiped out about a half billion dollars in the biotech's market cap. 

Ten days ago, the dialysis provider Fresenius said it would stop expanding an Omontys pilot program, after seeing "infrequent" allergic reactions in patients after their first dose. A "small number" of those were serious, the company said in a letter filed with the Securities and Exchange Commission.

Now, Takeda and Affymax say the reported reactions occurred within 30 minutes after a patient's first dose. Subsequent doses haven't caused any problems, the FDA said.

Nonetheless, the companies warned doctors--in an official "Dear Healthcare Provider" letter--to not only stop initiating therapy in new patients, but to stop dosing current patients as well. The overall reaction rate has been about 0.2%, with about one-third of those requiring "prompt medical attention and in some cases hospitalization," the companies said.

It's been less than a year since Omontys won FDA approval. It is the first competitor to Amgen's ($AMGN) longtime blockbuster Epogen. As a once-a-month injection, Omontys had ease of administration on its side; Epogen is injected three times a month or more. But despite safety questions of its own, Epogen has a strong hold on the market. Anticipating competition--from biosimilars as well as Omontys--Amgen negotiated several long-term supply contracts with dialysis providers.

Takeda and Affymax have been beating the pavement to negotiate supply deals of their own. Last July, Fresenius signed on to try Omontys at more than 100 dialysis centers, and expand use from there. In January, DSI Renal, one of the largest providers in the U.S., inked a similar deal.

By the end of last year, Omontys had brought in $34.6 million, Takeda reported; that was less than analysts had expected. A conference call for analysts, to discuss the recall, is scheduled for this morning.

Fresenius said Feb. 14 it was working to "analyze the full set of efficacy and safety profile information" on Omontys after more than 56,000 doses in about 18,000 patients. "We ... feel that the current scale of our experience with use of the drug is inadequate to complete this analysis," the company said in a letter.

- read the Affymax release
- get more from the FDA