title: Pro-apoptotic effect of an anti-CD37 scFv-Fc fusion protein, in combination with the anti-CD20 antibody, ofatumumab, on tumour cells from B-cell malignancies.
abstract: SMIP-016, a new anti-tumour agent, is a mouse/human chimeric fusion protein built on the ADAPTIR™ (modular protein therapeutic) platform targeting human CD37. In this study, for the first time, we examined pro-apoptotic activity of SMIP-016 in combination with monoclonal anti-CD20 antibody, ofatumumab (HuMax-CD20) in de novo chronic lymphocytic leukaemia (CLL) cells and in different B-cell neoplasm-derived lines. In CLL cells SMIP-016 exerted significant cytotoxicity (versus control - p=0.01). In the in vitro models, SMIP-016 was also distinctly active against Raji line (Burkitt lymphoma; BL) (versus control - p=0.007), Riva-1 line (diffuse large B-cell lymphoma; DLBCL) (versus control - p=0.002) and RPMI 8226 line (multiple myeloma cells; MM) (versus control - p=0.03). In studies combining SMIP-016 and ofatumumab, the cytotoxicity against CLL cells was significantly higher than the agents used alone (p<0.03). Remarkably enhanced cytotoxic activity of SMIP-016 and ofatumumab in combination was also observed in Raji and Riva-1 cell lines (p<0.01 and p<0.003, respectively). Importantly, both agents induced cytotoxicity at very low concentrations which suggests that potential side-effects may be decreased in clinical practice. The mechanism responsible for cytotoxicity of SMIP-016 in all the examined models was connected with caspase-dependent apoptosis. In majority of cell types SMIP-016 induced overexpression of Bax protein, as well as downregulation of Bcl-2, cIAP1 (p<0.03) and Smac/DIABLO (p<0.003) apoptosis-regulating proteins. In conclusion, our study demonstrated high pro-apoptotic activity of SMIP-016, especially in combination with ofatumumab, against ex vivo CLL cells, and BL or DLBCL in vitro cell lines. Thus, further preclinical studies in in vivo models are warranted, as this combination may be a promising therapeutic concept for treatment of those malignancies.
authors.affiliation: Department of Experimental Hematology, Medical University of Lodz, Poland.
authors.forename: Piotr
authors.initials: P
authors.lastname: Smolewski
authors.affiliation: Department of Experimental Hematology, Medical University of Lodz, Poland.
authors.forename: Pawel
authors.initials: P
authors.lastname: Robak
authors.affiliation: Department of Experimental Hematology, Medical University of Lodz, Poland.
authors.forename: Barbara
authors.initials: B
authors.lastname: Cebula-Obrzut
authors.affiliation: Department of Hematology, Medical University of Lodz, Poland.
authors.forename: Małgorzata
authors.initials: M
authors.lastname: Misiewicz
authors.affiliation: Department of Experimental Hematology, Medical University of Lodz, Poland.
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Mędra
authors.affiliation: Department of Experimental Hematology, Medical University of Lodz, Poland.
authors.forename: Agata
authors.initials: A
authors.lastname: Majchrzak
authors.affiliation: Department of Experimental Hematology, Medical University of Lodz, Poland; Department of Hematology, Medical University of Lodz, Poland.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Witkowska
authors.affiliation: Emergent Biosolutions, Seattle, WA, United States.
authors.forename: Scott
authors.initials: S
authors.lastname: Stromatt
authors.affiliation: Department of Hematology, Medical University of Lodz, Poland.
authors.forename: Tadeusz
authors.initials: T
authors.lastname: Robak
mesh_terms: D000818:Animals; D000906:Antibodies / Q000276:immunology / Q000494:pharmacology*; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000494:pharmacology*; D061067:Antibodies, Monoclonal, Humanized; D000951:Antigens, Neoplasm / Q000276:immunology; D000970:Antineoplastic Agents / Q000276:immunology / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D001402:B-Lymphocytes / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D053148:Caspase 3 / Q000378:metabolism; D053453:Caspase 9 / Q000378:metabolism; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D004357:Drug Synergism; D006801:Humans; D007141:Immunoglobulin Fc Fragments / Q000235:genetics / Q000276:immunology; D019012:Integrin beta1 / Q000276:immunology; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000378:metabolism / Q000473:pathology; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D051379:Mice; D011993:Recombinant Fusion Proteins / Q000276:immunology / Q000494:pharmacology; D057127:Single-Chain Antibodies / Q000235:genetics / Q000276:immunology; D059470:Tetraspanins / Q000276:immunology
chemical_list: D000906:Antibodies; D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D000951:Antigens, Neoplasm; D000970:Antineoplastic Agents; D051017:Apoptosis Regulatory Proteins; C059071:CD37 protein, human; D007141:Immunoglobulin Fc Fragments; D019012:Integrin beta1; D011993:Recombinant Fusion Proteins; C000593615:SMIP-016; D057127:Single-Chain Antibodies; D059470:Tetraspanins; D053148:Caspase 3; D053453:Caspase 9; C527517:ofatumumab
keywords: B-cell malignancies; Chronic lymphocytic leukaemia; Ofatumumab; SMIP-016; TRU-016