title: Comparability of Antibody-Mediated Cell Killing Activity Between a Proposed Biosimilar RTXM83 and the Originator Rituximab.
abstract: BACKGROUND
  Biosimilars are described as biological products that resemble the structure of original biologic therapeutic products, with no clinically meaningful differences in terms of safety and effectiveness from the original. A wide range of biosimilars are under development or are already licensed in many countries. Biosimilars are earning acceptance and becoming a reality for immunotherapy treatments mainly based on the alternatives for the commercial anti-CD20 monoclonal antibody rituximab. The most important mechanism of action reported for this antibody is the induction of antibody-dependent cell cytotoxicity (ADCC), which is associated with the polymorphisms present at the 158 position in the IgG receptor FcγRIIIa.
  
  
  OBJECTIVE
  The aim of the study was to validate the functional comparability between the proposed rituximab biosimilar RTXM83 and the original product. To achieve this we assessed the binding capacity and ADCC induction of this biosimilar, taking into account the different FcγRIIIa-158 polymorphisms.
  
  
  METHODS
  Binding capacity was evaluated by flow cytometry using CD20 positive cells and a wide range of antibody concentrations. The FcγRIIIa-158 polymorphisms were analyzed by polymerase chain reaction (PCR) followed by allele-specific restriction enzyme digestion. ADCC was measured by a colorimetric lactate dehydrogenase-release assay, using effector cells from donors with different FcγRIIIa-158 polymorphisms.
  
  
  RESULTS
  Binding capacity assay showed no differences between both products. Regarding ADCC, a similar relative potency was obtained between both antibodies, showing a higher response for the FcγRIIIa-158 valine/valine (V/V) polymorphism compared to the phenylalanine/phenylalanine (F/F), for both rituximab and RTXM83.
  
  
  CONCLUSIONS
  Our data strongly suggest the biocomparability between the proposed biosimilar and the originator rituximab, in antibody recognition and ADCC activity. Additionally, our results suggest that donors with the FcγRIIIa-158V/V polymorphism induce a higher ADCC response, as has been reported.
authors.affiliation: Laboratory of Molecular Oncology, Department of Science and Technology, Quilmes National University, R. Saenz Peña 352, Bernal, B1876BXD, Buenos Aires, Argentina.
authors.forename: Hector A
authors.initials: HA
authors.lastname: Cuello
authors.affiliation: Laboratory of Molecular Oncology, Department of Science and Technology, Quilmes National University, R. Saenz Peña 352, Bernal, B1876BXD, Buenos Aires, Argentina.
authors.forename: Valeria I
authors.initials: VI
authors.lastname: Segatori
authors.affiliation: Laboratory of Molecular Oncology, Department of Science and Technology, Quilmes National University, R. Saenz Peña 352, Bernal, B1876BXD, Buenos Aires, Argentina.
authors.forename: Marina
authors.initials: M
authors.lastname: Alberto
authors.affiliation: PharmADN, mAbxience Co., Buenos Aires, Argentina.
authors.forename: Analía
authors.initials: A
authors.lastname: Pesce
authors.affiliation: Laboratory of Molecular Oncology, Department of Science and Technology, Quilmes National University, R. Saenz Peña 352, Bernal, B1876BXD, Buenos Aires, Argentina.
authors.forename: Daniel F
authors.initials: DF
authors.lastname: Alonso
authors.affiliation: Laboratory of Molecular Oncology, Department of Science and Technology, Quilmes National University, R. Saenz Peña 352, Bernal, B1876BXD, Buenos Aires, Argentina. mrgabri@unq.edu.ar.
authors.forename: Mariano R
authors.initials: MR
authors.lastname: Gabri
mesh_terms: D000920:Antibody-Dependent Cell Cytotoxicity; D018951:Antigens, CD20 / Q000378:metabolism; D059451:Biosimilar Pharmaceuticals / Q000378:metabolism / Q000494:pharmacology*; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D011110:Polymorphism, Genetic; D017452:Receptors, IgG / Q000235:genetics / Q000378:metabolism; D000069283:Rituximab / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D018951:Antigens, CD20; D059451:Biosimilar Pharmaceuticals; C496124:FCGR3A protein, human; D017452:Receptors, IgG; D000069283:Rituximab; D007770:L-Lactate Dehydrogenase