Arsenic trioxide – a highly poisonous substance best known as an effective weed killer or pesticide and notorious for being a favourite ‘weapon’ of choice in murder mystery novels, is being re-invented as a treatment for a rare type of leukaemia.
It is already licensed as an orphan drug (the term for drugs intended to treat rare conditions) for patients who have relapsed after initial therapy for acute promyeloctytic leukaemia (APL).
But now, a research team led by Dr. Ardeshir Ghavamzadeh and Dr. Kamran Alimoghaddam at Tehran University of Medical Sciences in Iran, are running a trial of its use in newly diagnosed APL patients who have received no prior therapy, and they are impressed enough with its effectiveness to suggest that it should now be considered as a first-line treatment for APL. They also believe it is likely to prove effective in other cancers such as multiple myeloma.
Dr. Ghavamzadeh, professor of medicine at Tehran University, reported at the EORTC-NCI-AACR Symposium on Molecular Targets and Cancer Therapeutics in Geneva that two courses of the drug achieved complete remission in over 90% of the 63 patients in a Phase II study being carried out at the city’s Hematology, Oncology and Bone Marrow Transplant Center. 88.5% of patients were still alive with a mean survival time to date of nearly 34 months. Of 11 patients who relapsed, eight went back into remission after a third cycle of treatment. Six patients in the trial have died.
APL accounts for around 10% of acute myeloid leukaemias and affects an estimated 20,000 people worldwide each year. It is a cancer of the white blood cells, characterized by a rapid accumulation of abnormal white cells in the bone marrow and the blood, resulting in anaemia, bleeding and susceptibility to infections. It occurs in people of all ages, although it is more common in older people. The five-year survival rate for patients receiving the current optimum treatment of chemotherapy plus ATRA (All Trans-Retinoic Acid – a vitamin A-based substance) is between 60 and 80 percent.