Trial Information

Multicenter Trial Estimating the Persistence of Molecular Remission in Chronic Myeloid Leukaemia in Long Term After Stopping Imatinib

The gold standard for the treatment of chronic myeloid leukaemia (CML) is Imatinib, the
first tyrosine inhibitor (TKI) of BCR-ABL. Imatinib specifically targets the BCR-ABL
tyrosine kinase encoded by the BCR-ABL fusion gene, the molecular hallmark of CML. Regular
monitoring of BCR-ABL transcript levels by quantitative RT-PCR is of key importance for the
assessment of treatment response to imatinib.

Over time, an increasing proportion of imatinib-treated patients obtain a complete molecular
response (CMR), defined as an undetectable molecular residual disease. In a previous study,
STIM trial (PHRC 2006, stop Imatinib), 100 patients were included. The preliminary analysis
among 69 patients having a median follow up of 21 months shows that the probability to
maintain the CMR at 12 months is 45%. Our goal is actually to include up to 200 patients and
then let the STIM opened during 3 years in a way to determine the predictive factors of the
molecular relapse Discontinuation of treatment is proposed after checking selection criteria
and signing informed consent. The assessment of BCR-ABL in peripheral blood by quantitative
RT-PCR is performed every month during the first year then every two months second year then
every three months during 3 years.

The molecular relapse after imatinib discontinuation is defined by positive PCR for BCR-ABL
two times using RTQ-PCR with increasing of the transcript on two following assessment and or
a value> 0.1% i.e. lost of MMR. In case of molecular relapse it is recommended to
re-challenge an imatinib treatment. According to our experience the 50 patients well
documented who re challenged the treatment were sensitive again. The treatment of molecular
relapse by second generation tyrosine kinase inhibitors (dasatinib or nilotinib) will
possible in the current trial. It is important for all the French patients to be included in
a national trial to avoid discontinuation without evaluation.