The purpose of the study was to monitor minimal residue disease (MRD) among children with ALL and to evaluate the possibility of using this test to detect and monitor the minimal residual disease (MRD test) in the stratification of risk groups on a parallel basis with other recognised prognostic factors.
Materials and methods: 56 children, with de novo diagnosed ALL, comprised test group. Control group consisted of 10 healthy persons. DNA was isolated from peripheral blood and bone marrow. During research applied was the PCR method with the use of starters specific for conservative IgH and TCR delta gene fragments. ALL therapy was monitored by evaluation of MRD in the 15th and 33rd day of treatment and prior to supportive treatment. Stratification into risk groups, based on the MRD test results was compared with the stratification conducted in accordance with the recognised prognostic factors, such as: primary leucocytosis, steroid therapy response, drug resistance and karyotype.
Results: Among 52 children (92.8%) of the 56, which were tested prior to the start of treatment, obtained the sought for rearrangement, 90-120bp size stripe being an amplified regrouping of the VDJ fragment. Among all the tested healthy persons, the test result was negative. Testing the IgH and TCR delta gene regrouping allowed to demonstrate clonality of the neoplastic process during the diagnosis in 92.8% of the cases. In some of them the regrouping had a bi- or oligoclonal character. The number of patients with a positive MRD test result was dependent on the phase of treatment. Positive results were recorded among 10% of the patients (4/39) during clinical remission, among 86% (6/7) deceased and among 80% (4/5) suffering from relapse. Among 16.7% (2/13) of the patients with determined relapse or who died due to the course of illness process were also observed negative MRD test results. Steroid resistance was stated among 18/56 children, out of which 8/56 obtained a positive MRD test result in the 33rd day of treatment. Among 3 of them the result was maintained prior to supportive treatment. Leucocytosis during diagnosis above 50 thousand was recorded among 10/56 patients. Among 5 of them determined was rearrangement on the 33rd day of treatment, and for 1 prior to supportive treatment. Cytogenetic tests showed a correct karyotype for 19 out of 56 tested children. In this group steroid resistance was determined among 8 children, high preliminary leucocytosis among 5 and in 17 cases of the tested rearrangement. Stratification into therapeutic groups based on classical prognostic factors in most cases was the same with the stratification based on the MRD test results. The accuracy of the latter method was greater.
Conclusions: The use of MRD test has its application in risk group qualification. MRD test is helpful in determining relapses prior to the appearance of clinical symptoms. Among the tested group of children with ALL a positive MRD test result was a bad prognostic factor. It seams that the use of a combined analysis of the risk factors and the MRD test results in a significant manner contribute to a more complex evaluation of the patient's condition.