Dasatinib, nilotinib have similar favorable results against CML

NEW YORK (Reuters Health) - Patients with early chronic phase chronic myeloid leukemia (CML) have high response rates to either dasatinib (Sprycel) or nilotinib (Tasigna), according to two papers reported online December 14 in the Journal of Clinical Oncology.

Both papers were written by a single team, and each describes a phase II trial in which "the primary objective was to improve the major molecular response rate at 12 months from the expected 40% based on historical experience with standard-dose imatinib."

Lead author Dr. Jorge E. Cortes of the University of Texas M.D. Anderson Cancer Center, Houston, told Reuters Health by e-mail that because response rates to imatinib are so well documented, neither trial had a control group. "We know well what to expect with imatinib," he said.

Patients were assigned to the dasatinib study or the nilotinib study in alternating sequence. All were at least 18 years old and had chronic-phase CML, diagnosed no more than six months earlier, and none had received imatinib for more than one month.

Treatment in both studies continued until disease progression or toxicity.

The 62 participants in the dasatinib study were randomized to receive either 100 mg once daily or 50 mg twice daily. There were no major differences in treatment response between the two groups.

Of 50 patients who were observed for at least three months, 49 (98%) achieved a complete cytogenetic response within a median of three months and 41(82%) had a major molecular response within a median of six months.

In the nilotinib study, all 61 participants took 400 mg twice a day. Of 51 patients who were followed for at least three months, 50 (98%) had a complete cytogenetic response and 39 (76%) had a major molecular response within a median of three months.

Both drugs were well tolerated, according to the researchers.

"Both drugs appear to be very good, and we have no good grounds to say one is better than the other," Dr. Cortes said. He cautioned, however, that these "very encouraging" early responses need to be confirmed with longer term studies, some of which are already underway.

In the nilotinib report, the authors note that whether an early response to therapy improves long-term CML outcomes is controversial. Dr. Cortes told Reuters Health that he believes early response is important. "The longer the time it takes to achieve the response you want, the greater the risk for progression," he said.

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