Ariad leukemia drug helps chronic trial patients

CHICAGO, June 4 (Reuters) - A pivotal trial of Ariad Pharmaceuticals' experimental leukemia drug ponatinib showed it is effective in more than half of patients who had stopped responding to currently available drugs.

Ariad said it plans to file for U.S. and European regulatory approval of the drug in the third quarter of this year.

The study, presented here at a meeting of the American Society of Clinical Oncology, found that 54 percent of chronic myeloid leukemia (CML) patients with chronic-phase disease had a major response to ponatinib, meaning that at least two-thirds of their bone marrow was normal.

Forty-four percent of those patients achieved complete remission of their leukemia, a cancer of the bone marrow.

Of 64 evaluated chronic-phase CML patients with a genetic mutation known as T315I, 70 percent had a major response to the drug. The major response rate for chronic-phase patients without the mutation was 49 percent.

The trial involved 444 patients who had stopped responding to treatment with Tasigna, sold by Novartis, and Sprycel, sold by Bristol-Myers Squibb.

Both of the older drugs, known generically as nilotinib and dasatinib, are members of a class called tyrosine kinase inhibitors. A tyrosine kinase is a type of enzyme that can serve as a cell's "on" and "off" switch.

Ariad's drug is designed to target an abnormal tyrosine kinase that is closely associated with CML and Philadelphia chromosome positive acute lymphoblastic leukemia.

Side effects seen in the trial included rash (in 32 percent of patients), low platelet counts (35 percent), dry skin (30 percent), and abdominal pain (22 percent).

Ariad said 6 percent of patients developed inflammation of the pancreas.