A new STAT3-based potency assay for human G-CSF analog therapeutics

Area of Science:

• Biotechnology
• Pharmacology
• Cell Biology

Background:

• Recombinant human granulocyte colony-stimulating factor (rhG-CSF) therapies, including filgrastim and pegfilgrastim, are crucial for managing neutropenia in cancer patients.
• Current bioassays for rhG-CSF potency rely on murine cell proliferation, which suffers from inter-laboratory variability and interspecies receptor differences.
• These limitations hinder accurate assessment of rhG-CSF product bioactivity and may not fully reflect in vivo human responses.

Purpose of the Study:

• To establish a novel reporter cell line for a more specific and reliable rhG-CSF potency bioassay.
• To develop and qualify a reporter-based assay for pegylated rhG-CSF (PEG-rhG-CSF) products.
• To provide a platform for developing potency assays for other rhG-CSF therapeutics.

Main Methods:

• Development of a 293-CSF3R-STAT3Luc reporter cell line expressing the human G-CSF receptor and a STAT3-activated luciferase system.
• Establishment and qualification of a reporter-based potency bioassay using the developed cell line for PEG-rhG-CSF.
• Validation of the assay for linearity, accuracy, specificity, precision, and robustness.

Main Results:

• The 293-CSF3R-STAT3Luc cell line demonstrated selective response to rhG-CSF stimulation.
• The developed reporter-based potency bioassay was linear and accurate across a 25-200% potency range relative to reference material.
• The assay exhibited acceptable specificity, precision, and robustness, outperforming traditional proliferation assays.

Conclusions:

• A novel reporter cell line and associated bioassay provide a more reliable method for determining rhG-CSF potency.
• This assay platform addresses limitations of existing methods, offering improved accuracy and reduced variability for rhG-CSF biosimilars.
• The reporter cell assay platform holds potential for broader application in potency testing of rhG-CSF class therapeutics.