Role of the DNA Repair Machinery in Childhood B-Lineage Acute Lymphoblastic Leukemia: Aberrations of NBS 1, Fancd 2, Palb 2 Genes and Expression of BRCA 1 and BRCA 2

• Published in: Blood 2023-11, Vol.142 (Supplement 1), p.2982-2982
• Main Authors: Lo Nigro, Luca, La Cognata, Daria, Andriano, Nellina, Cannata, Emanuela, La Rosa, Manuela, Arrabito, Marta, Russo, Giovanna
• Format: Article
• Language: English
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood-2023-187333

Background. Successful treatment of B-lineageAcute Lymphoblastic Leukemia (B-ALL) in children has been related to novel biological findings and a better supportive therapy. Genomic aberrations have a major role in development of ALL and in the treatment response. Conventional treatment is based on chemotherapy, mainly acting on the structure of DNA in both leukemic and host cells. The result is a complete achievement of durable remission and/or a high incidence of toxicity. The role of DNA repair machinery in the occurrence of de novo or relapsed ALL and of high-grade toxicity is still unclear. We decide to dissect genes involved in the Fanconi Anemia (FA) pathway ( BRCA1, BRCA2, FANCD2 and PALB2), which cooperates with the Nijmegen breakage syndrome ( NBS1) gene. We evaluate the correlation of DNA repair machinery alterations with occurrence of relapse and/or with severe (III-IV grade - CTCAE) toxicity during chemotherapy treatment. Materials and Methods.The study was approved by the Local Clinical Research Ethics Committee (Catania-1). Written informed consents were obtained from the parents of each child involved in this research. We analyzed bone marrow (BM) samples from diagnosis and remission (Dx/Rem) of 111 children with B-ALL, diagnosed and treated at the Center of Pediatric Hematology Oncology, Catania Italy, from 2000 to 2017. These children were enrolled in three consecutive protocols of Associazione Italiana Ematologia Oncologia Pediatrica (AIEOP) [AIEOP-BFM ALL 2000; AIEOP-R 2006; AIEOP BFM ALL 2009]. Biological subgroups were as follow: 16 children presenting with t(1;19); 48 with t(12;21), 9 with t(9;22)/Ph+, 5 with a KMT2A (formerly MLL)rearrangement and 33 defined as “B-Others”. Traditional PCR method was used to determinate the NBS1 mutations in exons 3-6, followed by Sanger sequencing. FANCD2 and PALB2 mutations were investigated by multiplex ligation-dependent probe amplification (MLPA). Samples from healthy donors were used as wild-type controls. A real-time PCR assay was applied to evaluate the BRCA1 and BRCA2 genes expression using the SYBR green, fluorescent dye. We used specific primers for BRCA1 exons 14-15 and BRCA2 exons 15-16, respectively. The expression of BRCA1 and BRCA2 was determined as high (H) or low (L) using the Mean and the Median of fold change (FC) as cut-off. Results. Fifty-four patients (48%) out of 111 had more than one episode of severe toxicity during chemotherapy treatment. Twenty-one children (19%) with B-ALL