title: Distinct in vitro sensitivity of p53-mutated and ATM-mutated chronic lymphocytic leukemia cells to ofatumumab and rituximab.
abstract: Abnormalities in ATM and TP53 genes represent important predictive factors in chronic lymphocytic leukemia (CLL); however, the efficacy of CD20 targeting immunotherapy is only poorly defined in the affected patients. Therefore, we tested the in vitro response to ofatumumab (OFA) and rituximab (RTX) in 75 CLL samples with clearly defined p53 or ATM inactivation. Using standard conditions allowing complement-dependent cytotoxicity, i.e., 10 μg/mL of antibodies and 20% active human serum, we observed clear differences among the tested genetic categories: ATM-mutated samples (n = 17) represented the most sensitive, wild-type samples (n = 31) intermediate, and TP53-mutated samples (n = 27) the most resistant group (ATM-mut vs. TP53-mut: P = 0.0005 for OFA and P = 0.01 for RTX). The response correlated with distinct levels of CD20 and critical complement inhibitors CD55 and CD59; CD20 level median was the highest in ATM-mutated and the lowest in TP53-mutated samples (difference between the groups P < 0.01), while the total level of complement inhibitors (CD55 plus CD59) was distributed in the opposite manner (P < 0.01). Negligible response to both OFA and RTX was noted in all cultures (n = 10) tested in the absence of active serum, which strongly indicated that complement-dependent cytotoxicity was a principal cell death mechanism. Our study shows that (1) common genetic defects in CLL cells significantly impact a primary response to anti-CD20 monoclonal antibodies and (2) ATM-mutated patients with currently poor prognosis may potentially benefit from immunotherapy targeting CD20.
authors: Center of Molecular Medicine, CEITEC-Central European Institute of Technology, Masaryk University, Brno, Czech Republic; Department of Internal Medicine-Hematology and Oncology, University Hospital Brno and Faculty of Medicine, Masaryk University, Brno, Czech Republic.
authors: Ludmila
authors: L
authors: Sebejova
authors: Department of Internal Medicine-Hematology and Oncology, University Hospital Brno and Faculty of Medicine, Masaryk University, Brno, Czech Republic.
authors: Marek
authors: M
authors: Borsky
authors: Center of Molecular Medicine, CEITEC-Central European Institute of Technology, Masaryk University, Brno, Czech Republic; Department of Internal Medicine-Hematology and Oncology, University Hospital Brno and Faculty of Medicine, Masaryk University, Brno, Czech Republic.
authors: Zuzana
authors: Z
authors: Jaskova
authors: Core Facility-Proteomics, CEITEC-Central European Institute of Technology, Masaryk University, Brno, Czech Republic.
authors: David
authors: D
authors: Potesil
authors: Center of Molecular Medicine, CEITEC-Central European Institute of Technology, Masaryk University, Brno, Czech Republic; Department of Internal Medicine-Hematology and Oncology, University Hospital Brno and Faculty of Medicine, Masaryk University, Brno, Czech Republic.
authors: Veronika
authors: V
authors: Navrkalova
authors: Center of Molecular Medicine, CEITEC-Central European Institute of Technology, Masaryk University, Brno, Czech Republic; Department of Internal Medicine-Hematology and Oncology, University Hospital Brno and Faculty of Medicine, Masaryk University, Brno, Czech Republic.
authors: Jitka
authors: J
authors: Malcikova
authors: Department of Internal Medicine-Hematology and Oncology, University Hospital Brno and Faculty of Medicine, Masaryk University, Brno, Czech Republic.
authors: Martin
authors: M
authors: Sramek
authors: Center of Molecular Medicine, CEITEC-Central European Institute of Technology, Masaryk University, Brno, Czech Republic; Department of Internal Medicine-Hematology and Oncology, University Hospital Brno and Faculty of Medicine, Masaryk University, Brno, Czech Republic.
authors: Michael
authors: M
authors: Doubek
authors: Department of Internal Medicine-Hematology and Oncology, University Hospital Brno and Faculty of Medicine, Masaryk University, Brno, Czech Republic.
authors: Tomas
authors: T
authors: Loja
authors: Center of Molecular Medicine, CEITEC-Central European Institute of Technology, Masaryk University, Brno, Czech Republic; Department of Internal Medicine-Hematology and Oncology, University Hospital Brno and Faculty of Medicine, Masaryk University, Brno, Czech Republic.
authors: Sarka
authors: S
authors: Pospisilova
authors: Center of Molecular Medicine, CEITEC-Central European Institute of Technology, Masaryk University, Brno, Czech Republic; Department of Internal Medicine-Hematology and Oncology, University Hospital Brno and Faculty of Medicine, Masaryk University, Brno, Czech Republic.
authors: Jiri
authors: J
authors: Mayer
authors: Center of Molecular Medicine, CEITEC-Central European Institute of Technology, Masaryk University, Brno, Czech Republic; Department of Internal Medicine-Hematology and Oncology, University Hospital Brno and Faculty of Medicine, Masaryk University, Brno, Czech Republic. Electronic address: mtrbusek@fnbrno.cz.
authors: Martin
authors: M
authors: Trbusek
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000911:Antibodies, Monoclonal / Q000494:pharmacology*; D061067:Antibodies, Monoclonal, Humanized; D058846:Antibodies, Monoclonal, Murine-Derived / Q000494:pharmacology*; D018951:Antigens, CD20 / Q000187:drug effects / Q000276:immunology*; D000951:Antigens, Neoplasm / Q000187:drug effects / Q000276:immunology*; D064007:Ataxia Telangiectasia Mutated Proteins / Q000172:deficiency / Q000235:genetics* / Q000502:physiology; D018958:CD55 Antigens / Q000276:immunology; D018957:CD59 Antigens / Q000276:immunology; D003165:Complement System Proteins / Q000276:immunology; D003470:Culture Media; D004260:DNA Repair / Q000235:genetics; D019008:Drug Resistance, Neoplasm; D004354:Drug Screening Assays, Antitumor; D005260:Female; D016158:Genes, p53; D006801:Humans; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000235:genetics*; D000069283:Rituximab; D044967:Serum; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000172:deficiency / Q000502:physiology
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D058846:Antibodies, Monoclonal, Murine-Derived; D018951:Antigens, CD20; D000951:Antigens, Neoplasm; D018958:CD55 Antigens; D018957:CD59 Antigens; D003470:Culture Media; D009363:Neoplasm Proteins; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; C051590:CD59 protein, human; D000069283:Rituximab; D003165:Complement System Proteins; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; C527517:ofatumumab