FDA criticizes Genzyme study of leukemia drug

Just days before a key meeting to consider Genzyme Corp.’s application for a new leukemia drug to treat older patients, the Food and Drug Administration released a briefing document criticizing the Cambridge biotechnology company’s clinical study of the drug, called Clolar.

Genzyme said the drug deserves to be approved to treat adult acute myeloid leukemia in people who aren’t healthy enough to undergo chemotherapy, citing results of its study involving patients over 60 years old.

The company said it found older patients with the disease had a 45.5 percent overall remission rate when they took the treatment.

Clolar, the brand name for the drug clofarabine, won FDA approval in 2004 to treat a different form of leukemia - cancer of the blood or bone marrow - in patients under 21 who have had relapses after undergoing chemotherapy. Genzyme filed a new drug application Nov. 21 for older patients with acute myeloid leukemia.

The company and the FDA are scheduled to present their findings Tuesday to an outside panel of specialists, called the Oncological Drug Advisory Committee, which will make a recommendation. Such recommendations are typically followed by the agency.

But in the briefing document posted on the FDA’s website yesterday, regulators said Genzyme didn’t follow the agency’s guidance in designing its Phase II clinical study. While the FDA had advised the company to conduct a “randomized’’ study, comparing patients who took Clolar with those who underwent an alternative treatment or took a so-called sham drug, the company ran a “single-arm’’ study consisting only of patients who used Clolar.

The regulatory feedback suggests the FDA believes “this study was poorly conceived,’’ said Ira Loss, health care analyst for Washington Analysis, a research firm advising institutional investors on regulatory trends. “My strong sense is that the committee will recommend against approving the drug for this indication.’’

Shares of Genzyme, which has been working to get production problems at its Allston Landing plant under control, slid $1.37, or 2.4 percent, to $55.53 yesterday on the Nasdaq exchange.

Beth Trehu, product general manager for clofarabine at Genzyme, said the company wanted to run a randomized study, it was unable to get physicians to agree on a “comparative’’ treatment for the population of older patients with acute myeloid leukemia.

Nonetheless, said Trehu, “we think our study shows a very positive benefit/risk ratio, a very positive response rate, and very durable remissions. We’re hoping the [oncology] panel will recommend approving our drug based on its efficacy and safety.’’

Source : www.boston.com