Arsenic, a toxic compound, has a significant positive effect on the survival of patients with acute leukaemia, scientists have found.
Wake Forest University Baptist Medical Center researchers conducted the study.
"Patients with APL can achieve remission with standard treatment (chemotherapy plus ATRA, an oral vitamin A-based compound), but it often comes back," said Bayard L. Powell.
"Arsenic trioxide is then used to get them back into remission, often followed by a bone marrow transplant to try to cure the patient. For this study, we used arsenic as an early "consolidation therapy" after the initial standard treatment to essentially, as one of our first patients described, 'seal the deal' the first time around. Not only did the leukemia rarely return in the patients who received the arsenic, those patients also lived longer," he said.
Acute promyelocytic leukemia (APL) is associated with a very high risk of severe bleeding complications, including early death from bleeding into the brain.
Those with high white blood cell counts at diagnosis have slimmer chances of complete remission. If they survive initial treatment and enter remission, they are also more prone to relapse, at which point arsenic is introduced to push them back into remission.
While arsenic can be toxic, when manufactured under carefully-controlled conditions and used appropriately by doctors and nurses experienced in the treatment of cancer, can provide a significant health benefit.
The patients in the investigational group received arsenic trioxide intravenously for one hour, five days a week, for five weeks, with a two-week break between courses.
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.
The group who received arsenic also faired better in relapse rates and overall survival, researchers found.
"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," 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."
The findings appear in the November 11 issue of Blood.