Two Rare Pediatric Cases of TP53 -Mutated Acute Lymphoblastic Leukemia

Acute lymphoblastic leukemia (ALL) is the most common childhood malignancy, generally associated with high cure rates, though relapse remains a leading cause of mortality.TP53, located on chromosome 17p13, is a key tumor suppressor regulating cell cycle, apoptosis, and genomic stability.While TP53 mutations are rare at diagnosis, they are enriched in low-hypodiploid and relapsed ALL, conferring high-risk features and poor prognosis.We report two pediatric cases of TP53-mutated ALL with distinct clinical courses.The first case, a 10-year-old girl, presented with fever, gum bleeding, and cervical lymphadenopathy; bone marrow evaluation revealed precursor B-cell ALL with low-hypodiploid and a TP53 exon 7 missense mutation (c.743GA; p.Arg248Gln).She received BFM 2022 induction therapy, achieving morphological remission but remaining MRD-positive (1.5%), and attained MRD negativity (MRD0.01%)following high-risk consolidation, with haploidentical HSCT planned.The second case, a 12-year-old boy with late B-ALL relapse four years after initial remission, exhibited low-hypodiploid and a TP53 exon 4 missense mutation (c.370TG; p.Cys124Gly).Treatment with inotuzumab ozogamicin plus mini-Hyper-CVAD induced complete morphological and molecular remission (MRD0.01%),and he remains in sustained remission while awaiting haploidentical HSCT.TP53-mutated ALL represents a rare and aggressive subtype associated with high relapse rates and chemoresistance.Early molecular detection, incorporation of targeted immunotherapies, and timely allogeneic transplantation are essential strategies for improving outcomes in this high-risk group.