Mutations and Deletions of the TP53 Gene Predict Nonresponse to Treatment and Poor Outcome in First Relapse of Childhood Acute Lymphoblastic Leukemia

Purpose In the clinical management of children with relapsed acute lymphoblastic leukemia (ALL), treatment resistance remains a major challenge. Alterations of the TP53 gene are frequently associated with resistance to chemotherapy, but their significance in relapsed childhood ALL has remained controversial because of small studies. Patients and Methods Therefore, we systematically studied 265 first-relapse patients enrolled in the German Acute Lymphoblastic Leukemia Relapse Berlin-Frankfurt-Mu nster 2002 (ALL-REZ BFM 2002) trial for sequence and copy number alterations of the TP53 gene by using direct sequencing and multiplex ligation-dependent probe amplification. Results We observed copy number and sequence alterations of TP53 in 12.4% (27 of 218) of patients with B-cell precursor ALL and 6.4% (three of 47) of patients with T-cell ALL relapse. Backtracking to initial ALL in 23 matched samples revealed that 54% of all TP53 alterations were gained at relapse. Within B-cell precursor ALL, TP53 alterations...