Last week a report by Leukaemia & Lymphoma Research scientists identified a variation of a gene carried by 20% of the population that significantly affects responses to treatment for acute promyelocytic leukaemia (APL).
The Newcastle University team who ran the study found that by testing patients for the risk gene variant and increasing treatment doses accordingly, they were able to significantly improve survival rates.
This study represents yet another breakthrough in the treatment of APL. With complete cure rates of over 70%, considerably higher than most other types of leukaemia, this rare subset of acute myeloid leukaemia is a definite research ‘success story’.
Until the 1980s, chemotherapy was the only treatment available for APL and the cure rate was around 20%, with many patients bleeding to death in the early stages of treatment.
Survival rates were transformed by the introduction of all-trans retinoic acid (ATRA), a derivative of vitamin A, which was used in combination with chemotherapy. APL is uniquely sensitive to ATRA, which causes ‘apoptosis’ in the cancer cells. Apoptosis is the process in which cells programme their own death and ‘commit suicide’.
The use of arsenic
Arsenic trioxide is now used in treatment. This may seem strange to most people, with its reputation as a powerful poison, but it has proven highly successful after its introduction in recent years to treat relapsed APL. Indeed the medical properties of arsenic were acknowledged and it was widely used for many diseases until the early 20th century.
A 2009 study funded by Leukaemia & Lymphoma Research showed that by using a very sensitive test for signs of relapse among APL patients, arsenic could be used to actually prevent patients relapsing. The ‘minimal residual disease’ (MRD) test can identify a molecular relapse before any clinical signs and allows doctors to use pre-emptive treatment to prevent it altogether.
In the study of over 400 APL patients at Guys and St Thomas’ Hospital in London, MRD test monitoring and treatment with arsenic in the early stages cut relapse rates by 60%.
Increased understanding of the genetics behind blood cancer can lead to dramatic improvements in treatment. APL is caused by genetic changes involving chromosome 15 and 17 and Leukaemia & Lymphoma Research is investing over £250,000 into a new project looking at how these abnormalities can lead to different characteristics of the disease. Only then will doctors be able to design drugs to target the APL cells more effectively.
Henry - Science Communications team