Enzyme-linked immunosorbent assay for the quantitative determination of specific antibodies to Filgrastim in human serum and plasma with confirmation reagent (for 20 samples). The Assay Genie anti-filgrastim ELISA Kit is intended for the quantitative determination of Filgrastim anti-drug antibodies in serum and plasma. It is for professional use only.

The Assay Genie Antibody to Filgrastim ELISA is a sandwich assay for the determination of anti-filgrastim antibodies in serum and plasma samples. During the first incubation period, the drug filgrastim coated on the wall of the microtiter wells captures the antibodies to filgrastim in patient serum and plasma samples. After washing away the unbound components from samples, a Peroxidase-labelled conjugate (which detects IgG, IgM, IgA and IgE antibodies) is added to each well and then incubated. After a second washing step, the bound enzymatic activity is detected by addition of tetramethylbenzidine (TMB) chromogen-substrate. Finally, the reaction is terminated with an acidic stop solution. The intensity of the reaction colour is directly proportional to the concentration of anti-filgrastim antibodies in a sample.

Filgrastim is a recombinant, non-pegylated human granulocyte colony stimulating factor (G-CSF) analogue manufactured by recombinant DNA technology using a strain of E. coli. Chemically, it consists of 175 amino acid residues. The protein has an amino acid sequence that is identical to the natural sequence predicted from human DNA sequence analysis, except for the addition of an N-terminal methionine necessary for expression in E coli. Filgrastim binds to the G-CSF receptor and stimulates the production of neutrophils in the bone marrow. As a GCSF analog, it controls proliferation of committed progenitor cells and influences their maturation into mature neutrophils. Filgrastim also stimulates the release of neutrophils from bone marrow storage pools and reduces their maturation time. Filgrastim acts to increase the phagocytic activity of mature neutrophils.

In patients receiving cytotoxic chemotherapy, Filgrastim can accelerate neutrophil recovery, leading to a reduction in duration of the neutropenic phase. Filgrastim is used in patients with acute myeloid leukemia receiving induction or consolidation chemotherapy. It is also used in cancer patients receiving bone marrow transplant. In general, filgrastim increases neutrophil counts in order to decrease the risk of infection or duration of neutropenia. Neutropenia is an adverse event associated with chemotherapy. Filgrastim is also indicated for patients with severe chronic neutropenia. It mobilizes hematopoietic progenitor cells into the peripheral blood for collection by leukapheresis to allow for a more rapid engraftment.

Used in the treatment of chemotherapy-induced neutropenia by enhancing the production of neutrophils. Filgrastim acts on hematopoietic cells by binding to specific cell surface receptors thereby stimulating proliferation, differentiation, commitment, and end cell functional activation. When filgrastim was administered to cancer patients, it took 3-5 days to reach maximum absolute neutrophil count (ANC). Levels of neutrophils returned to baseline by 21 days following completion of chemotherapy. In the healthy volunteer trials, doubling the filgrastim subcutaneous dose from 5 to 10 mcg/kg resulted in a 16-19% increase in the ANC max and a 33-36% increase in the area under the effect curve for ANC.

As with any biologic therapeutic, immunogenicity, in the form of anti-filgrastim antibodies can occur. The demonstration of anti-filgrastim antibodies during treatment with filgrastim is a major concern. The Assay Genie Anti-Filgrastim ADA Quantitative ELISA Kit can be efficiently used for monitoring anti-filgrastim antibodies in biological samples and is for research use only.

NEUPOGEN® is the Amgen Inc. trademark for filgrastim