In chronic myeloid leukemia (CML) patients with an optimal response to therapy, tumor progression represents a very rare but possible event (ranging between one case in 10 thousand and one in a thousand), and yet not linked to the suspension of treatment. An Italian study published in the ‘American Journal of Hematology’ sheds light on a still controversial point. The work, coordinated by Carlo Gambacorti Passerini, professor of Hematology at the Milan-Bicocca University and director of the Hematology Unit of the Irccs San Gerardo dei Tintori Foundation in Monza, began in 2017 and involved 906 CML patients followed in Italian, French and German centers , Spanish and Canadian. The results are released today by Bicocca and San Gerardo, on the eve of World Chronic Myelogenous Leukemia Day.
CML – the University and IRCCS recall – is a form of leukemia which, thanks to the advent of specific drugs (tyrosine kinase inhibitors), has gone from a life expectancy of 2-3 years to one identical to that of the general population . This has led to a continuous increase in the number of patients living with the disease, estimated at around 2 million in developed countries. In the presence of an optimal response to treatments, defined as at least 4 years of therapy and the presence of a minimal residual leukemic cell (less than one in 10 thousand), it is usual to suggest that the patient suspend therapy. It is known that approximately half must then restart it due to a relapse of CML, but the practice of suspension is still safe because resuming treatment leads to a new remission in practically all patients. In the literature, however, some cases have been described in which suspension of therapy was associated with progression of CML, its evolution into acute leukemia and sometimes even death. These descriptions of individual cases, however, do not allow the risk of this event to be quantified.
This is the assumption from which the researchers from Bicocca and San Gerardo started. Patients enrolled in the study had to be eligible for suspension of therapy and were followed regardless of their decision whether to suspend it or not. Approximately 40% did not discontinue therapy, while 60% did. After a median monitoring time of more than 5 years and over 5 thousand person-years of follow-up available, a single case of disease progression was recorded in a 45-year-old German patient: a frequency of approximately one case in a thousand, which moreover it occurred in the group of patients who had not suspended therapy. Hence the authors’ conclusions. These results, they conclude, also indicate the great importance of regular intake of therapy before its suspension, and of optimal monitoring by the doctor after suspension.