(HealthDay News) – For patients with untreated de novo acute myeloid leukemia, the addition of gemtuzumab ozogamicin to standard frontline chemotherapy improves event-free, overall, and relapse-free survival, without causing excessive toxicity, according to a Phase 3 study published online April 5 in The Lancet.

To investigate whether the addition of low fractionated-dose gemtuzumab ozogamicin to standard frontline therapy would improve outcomes, Sylvie Castaigne, MD, from the Université Versailles-Saint Quentin in Le Chesnay, France, and colleagues conducted an open-label Phase 3 study in 26 hematology centers in France for 280 patients aged 50–70 years with previously untreated de novo AML. Participants were randomly assigned in a 1:1 ratio to a control group (140 patients) and a gemtuzumab ozogamicin group (140 patients), and the data for 139 patients were analyzed in each group.

The researchers found that complete response (with or without incomplete platelet recovery) to induction was seen in 75% of the control group and 81% of the gemtuzumab ozogamicin group (P=0.25). The estimated event-free survival at two years was significantly higher in the gemtuzumab ozogamicin group (40.8% vs. 17.1%; HR, 0.58). Overall survival (53.2% vs. 41.9%; HR, 0.69) and relapse-free survival (50.3% vs. 22.7%; HR, 0.52) were also significantly higher in the gemtuzumab ozogamicin group. Although hematological toxicity was more common in the gemtuzumab ozogamicin group (16% vs. 3%), there was no increase in the risk of toxicity-related death.

“The use of fractionated lower doses of gemtuzumab ozogamicin allows the safe delivery of higher cumulative doses and substantially improves outcomes in patients with acute myeloid leukemia,” the authors write.

One of the authors disclosed financial ties to Wyeth, which funded the study and jointly manufactures gemtuzumab.

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