Immunogenicity Assessment of Tbo-Filgrastim in Cancer Patients Receiving Chemotherapy

Introduction: Neutropenia is the primary cause of chemotherapy (CT) delays, interruptions, and dose reductions, potentially compromising patient outcomes, including survival and complete response rates. Granulocyte colony-stimulating factors (G-CSFs), which support the proliferation, differentiation, and activation of hematopoietic cells, reduce the incidence, severity, and duration of febrile neutropenia in CT patients. Tbo-filgrastim (Granix®) with a non-glycosylated methionyl group is a short-acting version of G-CSF approved since 2012 under a biologic license application in the United States. Recombinant proteins may induce an immune reaction. Generation of antidrug antibodies (ADAs) may have serious consequences, including anaphylaxis resulting from hypersensitivity, neutralization of endogenous counterparts by cross-reactive neutralizing antibodies (NAbs), and reduction of drug efficacy. The objective of this analysis is to evaluate the immunogenicity of tbo-filgrastim, including the presence of the binding antibodies and neutralizing antibodies against tbo-filgrastim and its endogenous counterpart (native G-CSF), in patients receiving CT for solid and hematologic malignancies.