Personalised cancer therapy a step closer

Scientists at King’s have for the first time been able to personalise treatment for leukaemia patients using a test that accurately predicts relapse. A UK study, funded by charity Leukaemia Research published in the Journal of Clinical Oncology, shows that individualising treatment reduces relapse rates by half.

The ‘minimal residual disease’ (MRD) test identifies a molecular relapse before any clinical signs and allows doctors to modify treatment accordingly. Previously the MRD test has been used to determine treatment for children diagnosed with leukaemia by separating them into high and low intensity treatment groups from the onset.

For the first time this study, led by Professor David Grimwade at King’s College London, used the MRD test sequentially to guide doctors treating an aggressive form of blood cancer called acute promyelocytic leukaemia (APL).

The study was conducted off the back of a large UK clinical trial, AML 15, which tested new treatment combinations for patients diagnosed with acute myeloid leukaemia (AML). Professor Grimwade worked specifically with APL patients, a subtype of AML, to evaluate how best to apply MRD testing for this group.

Professor David Grimwade, said, "Conventional methods for guiding treatment have long been suspected to be inadequate. We have shown that sequential MRD testing is the most powerful method of predicting relapse in APL and should be used pro-actively to guide treatment for every patient."

In the study, conducted at Guys and St Thomas’ Hospital in London, over 400 patients with APL had their treatment guided using the results of their MRD test alone. Patients were monitored every three months on a ‘sequential’ MRD testing regime. The study showed a dramatic reduction in the number of APL patients relapsing – falling by more than a half, from 12 percent to 5 percent since the study opened in 2003.

The MRD test provides an extremely sensitive reading of how many leukaemia cells a patient has in their blood throughout treatment and can detect levels down to 1 in 10,000 cells.  Here, sequential MRD testing was used to predict relapse throughout the patient’s illness and the subsequent pre-emptive treatment was very successful at maintaining relapse-free survival. 73 percent of patients on the trial were still cancer-free a year after the MRD test predicted relapse, thanks to early treatment.

In recent years, improvements in diagnosis and treatments have led to increased survival rates for APL and today, the main cause of death is from treatment related toxicity. The MRD test now allows doctors to address this by personalising treatment to suit each patient’s cancer, sparing many people intensive treatment.

Dr David Grant, Scientific Director at Leukaemia Research, said, "This is the first time doctors have been able to individualise treatment so precisely which shows the potential for improving survival rates. The success of the MRD test in treating APL can provide a model for similar treatment of other leukaemias."

(Source: King’s College London: Journal of Clinical Oncology: June 2009)