Some chronic myelogenous leukaemia (CML) patients can safely reduce their intake of a treatment drug to lessen the side effects, British researchers have told a major conference.
Scientists at the University of Liverpool, England, found that halving Tyrosine Kinase Inhibitor (TKI) is safe, leading to concerns that some patients are being over-treated unnecessarily.
Dr Mhairi Copland, of the Institute of Cancer Sciences, University of Glasgow, Scotland, told delegates at the 58th American Society of Hematology (ASH) Annual Meeting and Exposition in San Diego, USA, that this new study suggests that more patients may be able to safely reduce TKI therapy than was previously thought feasible
This is because it included some patients with a stable molecular remission level at international standard MR3, a level that the research team described as “good, but not perfect”.
Of the 174 study participants, 93% had no leukaemia rebound one year after cutting their TKI dose, and many reported a significant decrease in TKI-associated side effects within the first three months.
A total of 12 participants showed signs of leukaemia recurrence, all of whom regained a remission level of MR3 or better within four months of resuming a full TKI dose.
Dr Copland said: “Taken together, these findings might indicate that some patients are being unnecessarily over-treated.
“The other important implication is that patients do not have to have extremely low levels of leukaemia on very sensitive tests in order to safely try reducing their TKI dose.”
Just 2.4% of participants who began to the study with MR4 levels of leukaemia were significantly less likely to experience a leukaemia rebound compared with 18.4% of those classified as MR3.
Dr Copland said the low rebound rates suggest it is safe for MR3 patients to attempt to reduce their TKI dose and that any reduced side effects should become apparent within the first three months.
The study received funding from the University of Newcastle, England, and from the blood cancer charity Bloodwise.
* A second European study reported to the conference found that some patients can safely discontinue TKI use.
Some 821 patients took part in the Euro-Ski trial. Researchers said the length of TKI therapy was linked to the chances of successfully discontinuing treatment.
The researchers studied patients with extremely low levels of detectable disease markers at least a year before discontinuing treatment. They found that 52% showed no sign of disease recurrence two years after stopping treatment.
Researcher Dr Francois-Xavier Mahon, of the Bergonie Cancer Centre of the University of Bordeaux, Franc, said: “Many patients struggle between the decision to stop TKI use because of its side effects and the fear of remission.
"Because of the high number of patients included in this study, we think the results could help to inform future guideline recommendations for TKI use."
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