Prognostic Relevance of Recurrent Genetic Aberrations in Pediatric Acute Megakaryoblastic Leukemia

• Published in: Blood 2015-12, Vol.126 (23), p.2598-2598
• Main Authors: de Rooij, Jasmijn, Masetti, Riccardo, van den Heuvel-Eibrink, Marry M., Cayuela, Jean-Michel, Trka, Jan, Reinhardt, Dirk, Sonneveld, Edwin, Alonzo, Todd A., Fornerod, Maarten, Zimmermann, Martin, Pigazzi, Martina, Pieters, Rob, Meshinchi, Soheil, Zwaan, C. Michel, Locatelli, Franco
• Format: Article
• Language: English
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood.V126.23.2598.2598

Genetic abnormalities and early treatment response are the main prognostic factors in pediatric acute myeloid leukemia (AML). Non-Down Syndrome (non-DS) acute megakaryoblastic leukemia (AMKL) is a rare subtype of AML, with a poor prognosis. These cases present with diverse cytogenetic aberrations, which might be important for risk-group stratification. A well-known genetic aberration in non-DS-AMKL is t(1;22)(p13;q13), resulting in expression of the RBM15/MKL1(OTT/MAL) fusion transcript. In recent years, targeted and genome-wide sequencing has identified novel, recurrent molecular abnormalities in pediatric AMKL. New fusions identified are inv(16)(p13.3q24.3) resulting in CBFA2T3/GLIS2 (Gruber et al, Cell, 2012; Masetti et al, Blood, 2013) and t(11;12)(p15;p13) resulting in NUP98/KDM5A (de Rooij et al, Leukemia, 2013) as specific aberrations in pediatric non-DS AMKL. Also KMT2A(=MLL)-rearrangements are recurrent in non-DS AMKL. The prognostic relevance of these novel abnormalities is not determined in a large cohort, since this disease is rare. To assess frequencies, clinical characteristics and outcome parameters of recurrent cytogenetic aberrations of pediatric non-DS AMKL, databases of the BFM-SG, DCOG, AIEOP, and COG were combined. In this study, we analyzed 151 newly diagnosed pediatric non-DS AMKL cases diagnosed between 1998 and 2014 of whom a sample was available. All patients included were screened for NUP98/KDM5A, CBFA2T3/GLIS2 and RBM15/MKL1 with reverse transcriptase(RT-) PCR,and for KMT2A-rearrangements using split signal FISH and RT-PCR. To assess outcome, probability of event-free survival (pEFS) and probability of overall survival (pOS) were estimated by the Kaplan-Meier method, and groups were compared with the log-rank test; the cumulative incidence of non-response or relapse (pCIR) was analysed by the Kalbfleisch and Prentice method, and groups were compared with the Gray's test. A Cox regression analysis was done for EFS and relapse incidence with as co-variables cytogenetic subgroup, age, sex, WBC and stem cell transplantation (time dependent variable). Patients were treated with different protocols; however, all protocols consisted of intensive chemotherapy using an anthracycline and cytarabine backbone for both induction and consolidation; 26% of patients received stem cell transplantation (SCT) in first remission. Median age was 1.6 years (range 0.1-17.1 years), with 62% of the patients younger than 2 years at diagnosis; 45% of pati