[1468] Molecular Analysis of Myeloid Neoplasms with inv(3)(q21q26.2)/t(3;3)(q21;q26.2) Using Highly Multiplexed Sequencing

Megan O Nakashima, Heesun J Rogers, Hadrian Szpurka, Todd Moon, Valeria Visconte, Ali Tabarroki, Edy Hasrouni, Ramon Tiu, Jaroslaw Maciejewski, Andrew Schade, James R Cook, Felicitas L Lacbawan, Eric D Hsi. Cleveland Clinic, Cleveland, OH; Eli Lilly and Co., Indianapolis, IN

Background: Myeloid neoplasms with inv(3)(q21q26.2)/t(3;3)(q21;q26.2) [inv3/t3] share morphologic features and a dismal prognosis. EVI1(3q26.2) and components of the RAS pathway are thought to contribute to the pathogenesis of inv3/t3 neoplasms. However few comprehensive mutational analyses in inv3/t3 have been reported. We utilized the speed and sensitivity of highly multiplexed targeted sequencing to capture a broad view of genetic alterations in these neoplasms.
Design: We reviewed clinical and pathologic data and bone marrow (BM) biopsies from myeloid neoplasms in 19 patients with inv3/t3 by cytogenetics. DNA extracted from formalin-fixed paraffin-embedded BM was analyzed with the TruSeq Amplicon-Cancer Panel (Illumina, San Diego, CA), which targets 212 amplicons in 48 genes. Sanger sequencing of N/KRAS was performed when DNA was available. Kaplan-Meier survival analysis with log rank testing was used to evaluate overall survival (OS).
Results: Cases included 8 acute myelogenous leukemias (AML), 9 myelodyplastic syndromes (MDS), and 2 chronic myelogenous leukemias in blast crisis (CML-BC) with median age of 65 years. 79% of patients expired during follow-up (median 5.6 months). Common additional karyotypic abnormalities were -7/del7q (32%) and t(9;22) (16%). The TruSeq panel detected alterations in a median of 3 genes (range 2-8) per patient. Frameshift mutations were detected in TP53 (n=1), NPM1 (1) and HNF1a (3). Other frequent alterations included missense changes in GNAQ (n=10), TP53 (9), KDR (8), and FGFR2 (5). No mutations in JAK2, FLT3, KIT, IDH1, or MPL were detected. There were no mutations in N/KRAS detected by TruSeq, confirmed by sequencing (exons 1 and 2) in eight patients. There was no significant difference in OS between AML, MDS and CML-BC cases (9.0, 5.5, 6.0 mo, respectively, p=0.85). There was no OS difference between cases with or without GNAQ, TP53, KDR, and FGFR2 variants (log rank p>0.1 for all).
Conclusions: Our data indicate that AML, MDS, and CML-BC with inv3/t3 have an equally poor survival. Unlike previous reports of N/KRAS mutations in ∼25% of inv3/t3, none were detected in our cohort. Highly multiplexed targeted sequencing detected novel candidates for inv3/t3 pathogenesis in regulatory pathways other than the RAS pathway. Further studies will confirm and elucidate the importance of these genes in inv3/t3 neoplasms.
Category: Hematopathology

Tuesday, March 5, 2013 9:30 AM

Poster Session III # 178, Tuesday Morning

 

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