Analysis of the overall results revealed that event-free survival, defined as the time from study entry to first event (defined above), was significantly better for patients randomized to receive the arsenic trioxide consolidation therapy, For example, after three years, event-free survival was 80 percent in the arsenic group versus 63 percent in the non-arsenic group. Arsenic trioxide consolidation provided significant benefit to patients in the investigational group regardless of their initial prognosis based on white blood cell count and other risk factors.

The group who received arsenic also faired better in relapse rates and overall survival, researchers found. Out of 196 study participants who received at least one dose of arsenic after initial standard treatment, only seven individuals – four percent – relapsed within three years of follow-up.

“We think people who received the arsenic trioxide after initial standard treatment are likely cured,” Powell said. “There have been no relapses in that group after 36 months. The use of arsenic earlier in treatment improves the cure rate and survival, and it does so with little or no additional toxicity.”

The results are exciting, Powell said. “It gives us hope that, with the addition of arsenic trioxide earlier in treatment, we may be able to eliminate some of the chemotherapy and reduce toxicities and costs.”

However, 19 patients (eight percent) in each group died during the initial standard treatment, Powell pointed out, and those who were randomized to receive the arsenic never got a chance to benefit from it, since they didn’t live through the initial treatment.

“One of our next objectives is to reduce or eliminate these early deaths – most common in patients with high white blood cell counts – possibly by introducing arsenic even earlier than we did this time, as part of initial induction therapy, to help them achieve remission,” Powell said. “Some of these patients are at such high risk that they may need the arsenic just to get them into remission, so they have a chance.”

Powell’s co-authors in the North American Leukemia Intergroup study are Barry Moser, Ph.D., Wendy Stock, M.D., Richard M. Stone, M.D., and Richard A Larson, M.D., of Cancer and Leukemia Group B (CALGB), in Chicago, IL; Robert E. Gallagher, M.D., Jacob M. Rowe, M.D., and Martin S. Tallman, M.D., of the Eastern Cooperative Oncology Group (ECOG), in Brookline, MA; Cheryl L. Willman, M.D., Steven Coutre, M.D., and Frederick R. Appelbaum, M.D., of Southwest Oncology Group (SWOG), in San Antonio, TX; James H. Feusner, M.D., and John Gregory, M.D., of Children’s Oncology Group (COG), in Arcadia, CA; and Stephen Couban, M.D., of the National Cancer Institute of Canada Clinical Trials Group (NCIC-CTG), in Kingston, ON, Canada.

Source: Wake Forest University Baptist Medical Center