Prognostic significance of bi/oligoclonality in childhood acute lymphoblastic leukemia as determined by polymerase chain reaction

RESUMO

CONTEXT The CDR-3 region of heavy-chain immunoglobulin has been used as a clonal marker in the study of minimal residual disease in children with acute lymphoblastic leukemia. Southern blot and polymerase chain reaction studies have demonstrated the occurrence of bi/oligoclonality in a variable number of cases of B-lineage acute lymphoblastic leukemia, a fact that may strongly interfere with the detection of minimal residual disease. Oligoclonality has also been associated with a poorer prognosis and a higher chance of relapse. OBJECTIVES: To correlate bi/oligoclonality, detected by polymerase chain reaction in Brazilian children with B-lineage acute lymphoblastic leukemia with a chance of relapse, with immunophenotype, risk group, and disease-free survival. DESIGN: Prospective study of patientsÆ outcome. SETTING: Pediatric Oncology Unit of the University Hospital, Faculty of Medicine of Ribeiräo Preto, University of Säo Paulo. PARTICIPANTS: 47 children with acute lymphoblastic leukemia DIAGNOSTIC TEST Polymerase chain reaction using consensus primers for the CDR-3 region of heavy chain immunoglobulin (FR3A, LJH and VLJH) for the detection of clonality. RESULTS: Bi/oligoclonality was detected in 15 patients (31.9 percent). There was no significant difference between the groups with monoclonality and biclonality in terms of the occurrence of a relapse (28.1 percent versus 26.1 percent), presence of CALLA+ (81.2 percent versus 80 percent) or risk group (62.5 percent versus 60 percent). Disease-free survival was similar in both groups, with no significant difference (p 0.7695). CONCLUSIONS: We conclude that bi/oligoclonality was not associated with the factors investigated in the present study and that its detection in 31.9 percent of the patients may be important for the study and monitoring of minimal residual disease