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3902 Gene Expression Profiling Signatures Allow the Identification of Unclassifiable Leukemic B-Cell Lymphoid Neoplasms

Non-Hodgkin Lymphoma: Biology, excluding Therapy
Program: Oral and Poster Abstracts
Session: 622. Non-Hodgkin Lymphoma: Biology, excluding Therapy: Poster III
Monday, December 7, 2015, 6:00 PM-8:00 PM
Hall A, Level 2 (Orange County Convention Center)

Alba Navarro1*, Guillem Clot2*, Alejandra Martinez-Trillos3*, Itziar Salaverria1*, David Martin-Garcia1*, Nicola Trim4*, Veronica Fernandez2*, Neus Villamor5, Dolors Colomer5*, Magda Pinyol6*, Pedro Jares6*, Wendy N. Erber7, Adrian Wiestner8, Wyndham H. Wilson, MD, PhD9, Reiner Siebert, MD10*, Marta Aymerich5*, Armando Lopez-Guillermo11, �lex S�nchez12*, Elias Campo13, Estella Matutes3* and S�lvia Be�1*

1Institut d�Investigacions Biom�diques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
2Institut d�Investigacions Biom�diques August Pi i Sunyer (IDIBAPS), Hospital Cl�nic, Barcelona, Spain
3Hematopathology Unit, Hospital Clinic, Barcelona, Spain
4West Midlands Regional Genetics Laboratory, Birmingham, United Kingdom
5Hospital Cl�nic, Barcelona, Spain
6Genomics Unit, IDIBAPS, Barcelona, Spain
7Pathology, University of Western Australia, Crawley, Australia
8Hematology Branch, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD
9National Cancer Institute, Bethesda, MD
10Institute of Human Genetics, Christian-Albrechts-University Kiel, Kiel, Germany
11Hematology, Hospital Clinic, Barcelona, Spain
12Department of Statistics, University of Barcelona, Barcelona, Spain
13Hematophatology Unit, Hospital Clinic, Barcelona, Spain

Leukemic B-cell chronic lymphoproliferative disorders (B-CLPD) encompass a heterogeneous group of defined disease entities. However, around 10% of the cases cannot be reliably classified based on the current criteria and are considered B-CLPD not otherwise specified (B-CLPD NOS). Few recurrent mutations and genetic alterations have been reported in some entities, but none is specific.

We performed gene expression profiling (GEP) to develop a robust GEP-molecular classifier for leukemic B-CLPD. We analyzed purified blood of 189 B-CLPD, including 54 chronic lymphocytic leukemia (CLL), 54 mantle cell lymphoma (MCL), 12 follicular lymphoma (FL), 23 splenic marginal zone lymphoma (SMZL), 4 splenic diffuse red pulp lymphoma (SDRPL), 4 hairy cell leukemia (HCL), 4 HCL-variant (HCL-v), 6 lymphoplasmacytic lymphoma (LPL) and 28 B-CLPD NOS. We used a multiple step approach to build a GEP-array classifier and then analyzed an additional series as a validation cohort by quantitative PCR (qPCR). Mutational analysis of BRAF, MAP2K1, MYD88, NOTCH1, NOTCH2, SF3B1 and TP53 and copy number alterations were studied.

In the training set, a supervised analysis clustering revealed that each B-CLPD entity has a specific expression profile. By a multi-step GEP classifier using 43 genes (Table 1) we could classify CLL, SOX11-positive MCL (MCLc), HCL, FL, SOX11-negative MCL (MCLi) and HCL-v cases in six successive stages. However, we were not able to clearly identify distinct signatures for LPL, SMZL and SDRPL. Furthermore, we could classify 36% of B-CLPD NOS cases. Interestingly, the 43-gene signature identified in leukemic samples could also classify the 28 tumor splenic biopsies. Finally, we built a simple 8-gene predictive model using qPCR data (including: FMOD, KSR2, SOX11, MYOF, MME, CCND1, CXCR4, and CAMSAP2) that was used in an independent validation cohort and classified 14% B-CLPD NOS cases. The classification yield increased to 61% and 50%, for GEP-array and qPCR, respectively, when additional morphological, molecular and genetic features were considered.

Our findings support the use in a routine base of a simple test as a diagnostic tool that can be applied to help multiparameter interpretation in the classification of leukemic B-CLPD and specially B-CLPD NOS.

Table 1. Gene signatures (43 genes) and steps used for the GEP-array model.

Step model

B-CLPD

Specific signatures

1

CLL

FMOD, KSR2, ADTRP, CLNK, LEF1, FILIP1L, CTLA4, IGSF3, EBF1

2

MCLc

SOX11, PLEKHG4B, HDGFRP3, CNN3, PON2, SH3BP4, FCGBP, STMN1, FARP1, DBN1, NREP, NINL, MARCKSL1, MEX3D, CRIM1, KAZN

3

HCL

HPGDS, IL1R2, TJP1, PLOD2, EMP1, NOVA1

4

FL

MME, SLC2A5, SMAD1, PRDM15

5

MCLi

CCND1

6

HCL-v

TUSC1, LRP1B, KCNJ3, NRCAM, MS4A14, FAM129C, CXCR4

7

Miscellaneous

LPL-SDRPL-SMZL

No specific genes

CLL: chronic lymphocytic leukemia; FL: follicular lymphoma, HCL: hairy cell leukemia;

HCL-v: hairy cell leukemia variant; LPL, lymphoplasmacytic lymphoma; MCLc: conventional

SOX11-positive mantle cell lymphoma; MCLi: indolent SOX11-negative mantle cell lymphoma;

SDRPL, splenic diffuse red pulp lymphoma; SMZL, splenic marginal zone lymphoma.

Bold letters indicate some of the genes included in the simple qPCR model.

Disclosures: Lopez-Guillermo: Roche, Celgene, Mundipharma, Gilead, Novartis: Membership on an entity�s Board of Directors or advisory committees , Research Funding .

*signifies non-member of ASH