ASCO '11: Incyte Cancer Drug Gives Comfort

CHICAGO (TheStreet) -- Incyte's (INCY) experimental drug ruxolitinib significantly reduced the spleen size in patients with myelofibrosis compared to patients treated with best alternative care, according to results from a phase III study announced for the first time Saturday.

Based on these data and results from a previous phase III study conducted last year, Incyte and its partner Novartis (NVS) plan to seek regulatory approval of ruxolitinib later this quarter.

Myelofibrosisis is a disorder in which abnormal bone marrow stem cells produce scar tissue that replaces healthy marrow. Patients with myelofibrosis suffer from anemia and enlarged spleens. Approximately 3,500 people in the U.S. are diagnosed with myelofibrosis annually and about one-third of these patients develop acute myeloid leukemia or bone marrow failure.

If approved for myelofibrosis, ruxolitinib could generate sales in the range of $300 million to $500 million, according to analyst estimates.

The most recent ruxolitinib data come from a phase IIII study known as "COMFORT-II" in which 219 myelofibrosis patients were randomized to either ruxolitinib or best alternative therapy for 48 weeks. At the end of treatment, 28.5% of ruxolitinib-treated patients responded, meaning their spleen size was reduced by at least 35%, determined by independent imaging scans. By comparison, none of the patients treated with best alternative therapy responded.

The median duration of response to ruxolitinib therapy was 48 weeks.

The data from the COMFORT-II study will be presented at the American Society of Clinical Oncology (ASCO) annual meeting on Monday but were discussed in a press briefing Saturday afternoon.

"There aren't really any therapies that work for a sustained period in myelofibrosis, and we've urgently needed new treatments for this condition," said study co-author Dr. Alessandro Vannucchi of the University of Florence in Florence, Italy. "These patients responded very quickly to ruxolitinib -- within two to four weeks. This therapy has the potential to significantly change the treatment landscape for these patients, and could greatly improve their outlook."

Ruxolitinib has been associated in the past with relatively high incidence of thrombocytopenia, or low platelet counts, and anemia, or reduced red blood cells. Both of these principal side effects of the drug showed up as well in the COMFORT-II results, with ruxolitinib-treated patients reporting thrombocytopenia rates of 44.5% and anemia rates of 40%. Side effects due to the drug caused 8% of patients to discontinue the study.

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