Copy number variants signature in two patients with relapsed acute promyelocytic leukemia.

Abstract

e23207 Background: Nowadays, Acute Promyelocytic Leukemia (APL) is a disease entity with a very high rate of cure and an estimated 2-year overall survival of 97%. Early death, rather than resistant disease so common in all other subtypes of AML, has emerged as the major cause of treatment failure, and relapse is a very rare occurrence. Methods : We collected data of all the APL referred to our institution from 2014. Within 23 patients, we encountered 20 new diagnosis and 2 relapse of APL. We analyzed blasts in samples obtained from Bone Marrow with Single Nucleotide Polymorphisms Array Cytoscan HD. Results: We compared copy number alterations in both relapsed patients with alterations detected in the pool of 20 newly diagnosed APL and we found specific signatures of CNVs for each patient. There were several copy number alterations related to each patient: the first patient presented gain of ROBO2, GRIP1, CTNNB1, SOX6, PBX1, GRIK2, CDKAL1 and loss FAF1, CREBBP, SBF1; the second patient presented gain of ROBO1, MAPK10, CADPS2, APBA1 and loss of GRIP1 and MYB. Subsequently we focused our attention on ROBO and GRIP1genes because they were alterated in both relapsed patients: ROBO proteins are associated to K channels while GRIP1 is involved in various critical functions, for example in androgen receptor binding, beta-catenin binding, glucocorticoid receptor binding, and it is also a regulator of glutamate metabolism, a well-known pathway in Leukemic Stem Cells. Conclusions: APL relapse is a very rare entity, and it is announced to become rarer with the advances in first line therapy. Molecular characteristics are hard to analyze without an effort to collect and bank samples together from multiple institutions. Since relapses, especially relapses out of follow-up period, represent a sudden life-treating condition for patients, to predict patients at higher risk of relapse we selected two candidate genes that could be involved in pathways favoring relapse. By the analysis of ROBO 1-2 and GRIP1 at the diagnosis of APL we could establish a different and strict follow-up program for patients with these alterations. Acknowledgement: ELN,AIL,AIRC,prog. Regione-Università 2010-12 (L. Bolondi), FP7 NGS-PTL project,HARMONY.