CRLF2 OVER-EXPRESSION IS A POOR PROGNOSTIC MARKER IN CHILDREN WITH HIGH RISK T-CELL ACUTE LYMPHOBLASTIC LEUKEMIA

// Chiara Palmi 1 , Angela M. Savino 1 , Daniela Silvestri 2, 3 , Ilaria Bronzini 4 , Gunnar Cario 5 , Maddalena Paganin 4 , Barbara Buldini 4 , Marta Galbiati 1 , Martina U. Muckenthaler 6 , Cristina Bugarin 1 , Pamela Della Mina 7 , Stefan Nagel 8 , Elena Barisone 9 , Fiorina Casale 10 , Franco Locatelli 11 , Luca Lo Nigro 12 , Concetta Micalizzi 13 , Rosanna Parasole 14 , Andrea Pession 15 , Maria C. Putti 4 , Nicola Santoro 16 , Anna M. Testi 17 , Ottavio Ziino 18 , Andreas E. Kulozik 6 , Martin Zimmermann 19 , Martin Schrappe 5 , Antonello Villa 7 , Giuseppe Gaipa 1 , Giuseppe Basso 4 , Andrea Biondi 3 , Maria G. Valsecchi 2 , Martin Stanulla 19 , Valentino Conter 3 , Geertruy te Kronnie 4 , Giovanni Cazzaniga 1 1 Centro Ricerca M. Tettamanti, Clinica Pediatrica, Universita di Milano Bicocca, Fondazione MBBM/Ospedale San Gerardo, Monza, Italy 2 Center of Biostatistics for Clinical Epidemiology, Department of Health Sciences, University of Milano-Bicocca, Milan, Italy 3 Clinica Pediatrica, Universita di Milano Bicocca, Fondazione MBBM/Ospedale San Gerardo, Monza, Italy 4 Laboratory of Onco-Hematology, Department SDB, Universita di Padova, Padova, Italy 5 Department of Pediatrics, University Hospital Schleswig-Holstein, Campus Kiel, Kiel, Germany 6 Department of Pediatric Oncology, Hematology and Immunology, University of Heidelberg and EMBL/Medical Faculty Molecular Medicine Partnership Unit, Heidelberg, Germany 7 Microscopy and Image Analysis Consortium, Universita di Milano-Bicocca, Monza, Italy 8 Department of Human and Animal Cell Lines, Leibniz-Institute DSMZ - German Collection of Microorganisms and Cell Cultures, Braunschweig, Germany 9 Pediatric Onco-Hematology, Stem Cell Transplantation and Cellular Therapy Division, Regina Margherita Children’s Hospital, Turin, Italy 10 Pediatric Oncology Service, Pediatric Department of 2nd University of Naples, Naples, Italy 11 Department of Pediatric Hematology/Oncology, IRCCS Ospedale Bambino Gesu, Rome - University of Pavia, Pavia, Italy 12 Center of Pediatric Hematology Oncology, Azienda Ospedaliero-Universitaria “Policlinico Vittorio Emanuele”, Catania, Italy 13 Hematology/Oncology Unit, G. Gaslini Children’s Hospital, Genoa, Italy 14 Department of Pediatric Hemato-Oncology, Ospedale Pausilipon, Napoli, Italy 15 Department of Pediatrics, “Lalla Seragnoli” Hematology-Oncology Unit, University of Bologna, Bologna, Italy 16 Department of Pediatrics, Division of Pediatric Hematology-Oncology, University “A. Moro” of Bari, Bari, Italy 17 Division of Hematology, Department of Biotechnologies and Hematology, “Sapienza” University of Rome, Rome, Italy 18 Pediatric Hematology and Oncology Unit, A.R.N.A.S. Civico, Di Cristina and Benfratelli Hospital, Palermo, Italy 19 Department of Paediatric Haematology and Oncology, Hannover Medical School, Hannover, Germany Correspondence to: Giovanni Cazzaniga, email: gianni.cazzaniga@hsgerardo.org Andrea Biondi, email: abiondi.unimib@gmail.com Keywords: CRLF2, pediatric leukemia, T acute lymphoblastic leukemia, prognostic marker, high risk Received: May 20, 2016 Accepted: July 01, 2016 Published: July 15, 2016 ABSTRACT Pediatric T-ALL patients have a worse outcome compared to BCP-ALL patients and they could benefit from new prognostic marker identification. Alteration of CRLF2 gene, a hallmark correlated with poor outcome in BCP-ALL, has not been reported in T-ALL. We analyzed CRLF2 expression in 212 T-ALL pediatric patients enrolled in AIEOP-BFM ALL2000 study in Italian and German centers. Seventeen out of 120 (14.2%) Italian patients presented CRLF2 mRNA expression 5 times higher than the median ( CRLF2-high ); they had a significantly inferior event-free survival (41.2%±11.9 vs. 68.9%±4.6, p=0.006) and overall survival (47.1%±12.1 vs. 73.8%±4.3, p=0.009) and an increased cumulative incidence of relapse/resistance (52.9%±12.1 vs. 26.2%±4.3, p=0.007) compared to CRLF2-low patients. The prognostic value of CRLF2 over-expression was validated in the German cohort. Of note, CRLF2 over-expression was associated with poor prognosis in the high risk (HR) subgroup where CRLF2-high patients were more frequently allocated. Interestingly, although in T-ALL CRLF2 protein was localized mainly in the cytoplasm, in CRLF2-high blasts we found a trend towards a stronger TSLP-induced pSTAT5 response, sensitive to the JAK inhibitor Ruxolitinib. In conclusion, CRLF2 over-expression is a poor prognostic marker identifying a subset of HR T-ALL patients that could benefit from alternative therapy, potentially targeting the CRLF2 pathway.