Mayo clinic study links anemia drugs to leukemia risk.

Anemia drugs from Amgen and Johnson & Johnson may raise the risk that patients with a bone marrow disease will later develop leukemia, according to an analysis of 30 years of patient records, Bloomberg News reported Dec. 11.

Mayo Clinic researchers reviewed records of 311 patients with primary myelofibrosis, a scarring of the bone marrow, from 1976 to 2006. The drugs--Aranesp and Epogen from Amgen and Procrit from Johnson & Johnson--were linked to leukemia among 27 patients who developed the disease, according to research presented at the American Society of Hematology meeting in Atlanta.

Past studies linked anemia drugs to heart attack, stroke and death when used in high doses.

The study also found a higher risk of leukemia among patients who took danazol, a modified form of testosterone. Risk was also higher for patients with a high count of immature leukemia cells and a low number of platelet cells in the blood. Patients who took other treatments, like thalidomide and interferon-alpha, had no higher risk, researchers said.

Patients with primary myelofibrosis feel fatigued, and they sometimes take an anemia drug to stimulate growth of oxygen-carrying red blood cells.

The findings needed to be confirmed in a trial to answer the question about anemia drug risk, Ayalew Tefferi, M.D., a Mayo Clinic hematologist and the study's lead investigator, said in a statement.

"While we cannot take these findings as an absolute, at the same time, they cannot be ignored," Tefferi said. "Treatment decisions regarding the use of anemia drugs in patients with primary myelofibrosis should carefully be evaluated."

In November, FDA strengthened the black box safety warning on the drugs to reflect concerns that they might elevate risk of death, heart attack, stroke and the progression of certain cancers.

Amgen said that preliminary follow-up results from the independent PREPARE breast cancer study showed that the group that received Aranesp with chemotherapy prior to surgery had numerically more deaths and reports of tumor growth than the control group, Reuters reported Dec. 6.

At the time, Amgen cautioned that no conclusions should be drawn from the data until the final study report is completed.

Separately, Johnson &Johnson's Ortho Biotech announced results from an updated analysis of data from a study in which a group of chemotherapy-treated patients with advanced cervical cancer used its anemia drug, Procrit, to maintain hemoglobin levels above 12 grams per deciliter of blood.

The data showed a statistically non-significant trend toward decreased progression-free and overall survival in the patients treated with Procrit, Ortho said.

The study, conducted by the Gynecologic Oncology Group (GOG), was terminated in 2003 due to potential concerns about the formation of potentially life-threatening blood clots in patients receiving Procrit.

Ortho said the updated analysis provided more evidence to support recent anemia drug label changes, which warn doctors to use the lowest dose needed to avoid transfusions, while not exceeding an upper hemoglobin safety limit of 12 grams per deciliter of blood.