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3129 Complex Karyotype Subtypes at Chronic Lymphocytic Leukemia Diagnosis Refine the Risk of Developing a Richter Syndrome. the Richter Syndrome Scoring SystemClinically Relevant Abstract

Program: Oral and Poster Abstracts
Session: 641. CLL: Biology and Pathophysiology, excluding Therapy: Poster III
Hematology Disease Topics & Pathways:
Leukemia, Diseases, CLL, Technology and Procedures, cytogenetics, Clinically relevant
Monday, December 7, 2020, 7:00 AM-3:30 PM

Andrea Visentin, MD PhD1*, Gian Matteo Rigolin2*, Francesca Romana Mauro, MD, PhD3*, Annalisa Martines, PhD4*, Federica Frezzato, PhD5*, Silvia Imbergamo, MD6*, Stefano Pravato, MD6*, Leila Romano Gargarella, MD6*, Maria Antonella Bardi7*, Mauro Nanni, PhD3*, Francesco Piazza8, Monica Facco, MS9*, Robin Foà, MD3, Gianpietro Semenzato, MD10*, Laura Bonaldi, MD11*, Antonio Cuneo, MD12* and Livio Trentin, MD13

1Hematology and Clinical Immunology Unit, Department of Medicine, Hematology and Clinical Immunology Unit, Department of Medicine, University of Padua, Padova, Italy
2Hematology, St. Anna University Hospital, Cona, Ferrara, Italy
3Hematology, Department of Translational and Precision Medicine, 'Sapienza' University, Rome, Italy
4Immunology and Molecular Oncology Unit, Veneto Institute of Oncology IOV-IRCSS, Padova, Italy
5Hematology and Clinical Immunology unit, Department of Medicine, University of Padua, Padova, Italy
6Hematology and Clinical Immunology unit, Department of Medicine, University of Padua, Padua, Italy
7Haematology Section, Ferrara, ITA
8Hematology and Clinical Immunology Unit, Department of Medicine, University of Padova, Padua, Italy
9Hematology and Clinical Immunology Unit, Department of Medicine, University of Padua, Padova, Pa, ITA
10Hematology and Clinical Immunology Unit, Department of Medicine, University of Padua, Padua, Italy
11Immunology and Molecular Oncology Unit, Veneto Institute of Oncology IOV-IRCSS, Padua, Italy
12Hematology section, Department of Medical Sciences, University of Ferrara - Azienda Ospedaliera-Universitaria di Ferrara, University of Ferrara, Ferrara, Italy
13Hematology and Clinical Immunology Unit, Department of Medicine-DIMED, University of Padua, Padua, Italy

INTRODUCTION. Richter syndrome (RS), the transformation of chronic lymphocytic leukemia (CLL) into an aggressive lymphoma, is a rare but a life threatening complication. Complex karyotype (CK), defined by the presence of ≥3 chromosomal lesions, is a heterogeneous cytogenetic category associated with a shorter survival in CLL, but its impact on the evolution into a RS has not been investigated. Among CK cases, those with≥5 lesions (highCK) and those with major structural abnormalities [type-2 CK (CK2)] display a more aggressive clinical course. The aim of this study was to assess the impact of CK subtypes on the risk of CLL evolution into a RS.

METHODS. We performed a retrospective study in 3 Italian CLL centers. Stimulated cytogenetic with CpG+IL2 was performed in 540 patients within the first year after CLL diagnosis. CK cases with unbalanced translocations, additions, insertions, derivative or marker chromosomes were classified as type-2 CK (CK2). Instead, high-CK cases were those presenting at least 5 chromosome abnormalities. An IGHV gene sequence homology ≥98% was considered as unmutated (U-IGHV), as opposed to mutated (M-IGHV). TP53 disruptions (TP53dis) included deletions and/or mutations. Time to Richter syndrome (TTRS) was calculated from CLL diagnosis to either histologically confirmed diffuse large B-cell lymphoma transformation or last known follow-up visit. Survival curves were compared with the log-rank test and p<0.05 was considered as significant. Hazard ratio (HR) was calculated by multivariate analysis.

RESULTS. Among the 540 patients, the median age at diagnosis was 63±12 years, 61% were males, 76% were at Binet stage A, 52% were U-IGHV, 11% had TP53dis, 20% harbored a CK. According to the qualitative classification of CK subtypes, 78/107 (73%) were CK2, whereas, with regards to the number of chromosome lesions, 52/107 (49%) were classified as high-CK. High-CK was present in 63% of CK2 patients. Seventeen % of patients died and 5% developed a RS over a median follow-up of 7 years.

Overall, the rate of RS after 5 and 10 years from the diagnosis of CLL was 2.6% and 12%. We observed that patients who developed a RS were more commonly at a more advanced Binet stage at CLL diagnosis (46% vs 23%, p=0.0113) and displayed more frequently an U-IGHV status (79% vs 56%, p=0.0191), TP53 abnormalities (32% vs 10%, p=0.0043), CK2 (46% vs 13%, p<0.0001) and a high-CK (39% vs 8%, p<0.0001) profile, as compared to patients who did not developed RS.

By univariate and multivariate analysis, the presence of a CK (overall), of a CK2 and of a high-CK subtypes were all significantly associated with a shorter TTRS, together with U-IGHV status, TP53dis, 11q- by FISH and Binet stage B-C. Patients with a CK2 (HR=5.6 p<0.0001) and/or a high-CK (HR=6.9 p<0.0001) harbored the highest risk of developing a RS, with a 10-year TTRS of 38% and 41%, respectively, vs 8% of patients without a CK. Other variables associated with TTRS at univariate and multivariate analysis were Binet stage B-C, U-IGHV, 11q-, TP53 dis.

By integrating the statistically significant variables, we developed a hierarchical model based on HR values (Figure 1): 15% of patients were classified as high-CK and/or CK2, for whom the 10-year TTRS was 31% and the HR 13; 45% were U-IGHV/TP53dis/11q-/Binet B-C and showed a 10-year TTRS of 12% and the HR 3; 40% were M-IGHV without CK and TP53 wild-type, the 10-year TTRS was only 3%. This model was confirmed in multivariate analysis and internally validated (p<0.0001). Moreover, our RS scoring system prove to better forecast the risk to develop RS that the hierarchical FISH score, the CLL-IPI and the Barcelona-Brno score, based both lower prediction error and Akaike index.

CONCLUSIONS. We herein identified variables associated with a higher risk of developing a RS and recapitulated them into a RS scoring system. Remarkably, patients harboring a CK subtype at CLL diagnosis have the highest risk of developing a RS and should be carefully monitored during the clinical follow-up.

Disclosures: Visentin: Gilead: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Abbvie: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Rigolin: Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Gilead: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Mauro: Octopharma: Consultancy; Astrazeneca: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Jannsen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Foà: Roche: Membership on an entity's Board of Directors or advisory committees; Roche: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Incyte: Speakers Bureau; Novartis: Speakers Bureau. Semenzato: Takeda: Honoraria; Roche: Honoraria; Abbvie: Honoraria. Cuneo: Gilead: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Astra Zeneca: Honoraria; Abbvie: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Roche: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Trentin: Takeda: Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Octapharma: Membership on an entity's Board of Directors or advisory committees; Shire: Honoraria.

*signifies non-member of ASH