Genzyme Corporation announced today that the FDA provided a complete response letter regarding the company's supplemental New Drug Application for Clolar® (clofarabine) in previously untreated older adult patients with acute myeloid leukemia (AML) and at least one unfavorable baseline prognostic factor. The agency recommended a randomized, controlled clinical study be conducted for label expansion of Clolar in this indication. In September, the FDA Oncologic Drugs Advisory Committee voted 9 to 3 that data from a randomized, controlled trial was necessary to establish the efficacy and safety of Clolar in the proposed adult AML indication. Genzyme had sought approval to expand the indication based on the findings from a single-arm trial in an adult AML population. Genzyme intends to request a meeting with the FDA to discuss the optimal path forward, including what additional or ongoing studies may satisfy regulatory requirements. Genzyme is conducting a randomized, placebo-controlled Phase 3 trial (CLASSIC I) comparing clofarabine in combination with cytarabine to cytarabine alone in relapsed and refractory adult AML patients 55 years old or older. The trial continues to exceed patient accrual expectations, and results are expected in 2011. Clofarabine, which is an approved agent in the treatment of relapsed or refractory pediatric acute lymphoblasic leukemia (ALL) after at least two prior regimens, is also being investigated in clinical trials by many of the leading AML experts and major cooperative leukemia investigation groups in the United States and Europe.