Affymax anemia drug meets study goals, but safety data sends shares down 64 percent

Affymax shares plunge on drug safety concerns

NEW YORK — Shares of Affymax Inc. plunged Monday after late-stage trial data showed certain patients taking its experimental anemia treatment had a higher percentage of heart-related side effects resulting in death, unstable angina and irregular heart rhythm.

The drug, Hematide, met key goals in late-stage studies focusing on patients with chronic renal failure, proving as effective as current standard treatments at maintaining patients’ hemoglobin. Anemia is characterized by a lack of oxygen in the blood due to deficient levels of hemoglobin, which carries oxygen from the lungs throughout the body.

But a subgroup of patients not on dialysis experienced a higher rate of side effects than those taking standard treatments — 21.6 percent versus 17.1 percent. Shares plunged $14.80, or 64 percent, to $8.21 in morning trading.

“We are continuing to evaluate the data, in particular the non-dialysis studies, and the impact on the timing of an NDA submission,” said Affymax CEO Arlene M. Morris.

The four late-stage studies involved 2,609 patients. The median duration of follow-up for patients on Hematide in the trials was 1.3 years.

Anemia affects many patients with chronic kidney disease, worsening as patients progress towards kidney failure and need dialysis treatment. According to the National Kidney Foundation, 26 million Americans have chronic kidney disease.