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Assay system development to measure the concentration of sargramostim with high specificity in patients with autoimmune pulmonary alveolar proteinosis after single-dose inhalation.

Research paper by Ryu R Nakano, Kazuhide K Nakagaki, Yuko Y Itoh, Utako U Seino, Takahiro T Ueda, Ryushi R Tazawa, Nobutaka N Kitamura, Takahiro T Tanaka, Koh K Nakata

Indexed on: 14 Jul '18Published on: 14 Jul '18Published in: Journal of Immunological Methods



Abstract

During a clinical trial of a Saccharomyces cerviciae-derived recombinant human granulocyte-macrophage colony stimulating factor (rhGM-CSF), sargramostim, in patients with autoimmune pulmonary alveolar proteinosis (aPAP), we conducted a pharmacokinetic study of single-dose sargramostim inhalation. Several problems were encountered whereby sargramostim formed an immune-complex with GM-CSF autoantibodies (GMAbs) immediately after entering the body; thus, we could not measure the concentration of sargramostim using a commercial high sensitivity enzyme-linked immunosorbent assay (ELISA). Moreover, the ELISA could not discriminate inhaled sargramostim from intrinsic GM-CSF. To solve these problems, we developed a novel ELISA system with a capture antibody that is specific for sargramostim and a detection antibody capable of binding with GM-CSF. This system quantified the serum sargramostim concentration, but not E. coli-, CHO-, or HEK293T-derived human recombinant GM-CSF. Using this system, serum pharmacokinetics were estimated in five patients after inhalation of 250 μg sargramostim, with a mean Cmax of 9.7 ± 2.85 pg/ml at a Tmax of 2 ± 1.22 h. Copyright © 2017. Published by Elsevier B.V.