CHOZN® CHO K1 Host Cell Line

Overview

The CHOZN® CHO K1 Host Cell Line is a genetically engineered, suspension-adapted Chinese Hamster Ovary (CHO) cell line developed by Merck for robust, scalable, and regulatory-compliant production of recombinant therapeutic proteins. Engineered from the parental CHO-K1 lineage, this cell line features targeted genomic modifications—including integration of the GS (glutamine synthetase) gene knockout and insertion of proprietary locus-specific landing pads—that enable rapid, stable, high-yield monoclonal antibody (mAb) and fusion protein expression under chemically defined, animal-component-free conditions. Its design aligns with modern bioprocess requirements: elimination of serum dependence, compatibility with single-use bioreactor systems, and intrinsic suitability for process intensification strategies such as perfusion and high-density fed-batch culture. As a cGMP-stored master cell bank (MCB), it supports Phase I–III clinical manufacturing and commercial supply when deployed within a validated platform process.

Key Features

• Suspension-adapted phenotype enabling homogeneous growth in stirred-tank and wave bioreactors without microcarrier dependency
• Full serum-free and animal-component-free performance in multiple commercially available chemically defined media (e.g., EX-CELL® CD CHO, ActiPro™, and PowerCHO™ 2)
• Genetically stabilized GS-knockout background facilitating efficient selection of high-expressing clones via methionine sulfoximine (MSX) pressure
• Pre-qualified for use with Merck’s CHOZN® Targeted Integration System (TIS), ensuring reproducible transgene insertion at a transcriptionally active, open chromatin locus
• Supplied with comprehensive documentation package including Certificate of Analysis (CoA), Cell Line History Report, Mycoplasma Test Report, and STR profiling data
• cGMP-compliant storage of Master and Working Cell Banks at Merck’s qualified cryogenic facility (ISO 9001 & ISO/IEC 17025 accredited)

Sample Compatibility & Compliance

The CHOZN® CHO K1 Host Cell Line is compatible with standard upstream bioprocessing workflows across stainless steel and single-use platforms, from 125 mL shake flasks to 2,000 L bioreactors. It has been functionally validated for use with industry-standard transfection reagents (e.g., PEIpro®, FuGENE® HD) and electroporation systems (e.g., MaxCyte STX). All supporting materials—including recommended basal media, feeds, and process analytics kits—undergo rigorous lot-release testing per Merck’s internal quality specifications. The cell line and associated documentation meet ICH Q5A(R2) requirements for characterization of mammalian cell substrates and support regulatory filings under FDA 21 CFR Part 610, EMA Guideline on Quality, Non-Clinical and Clinical Requirements for Investigational Medicinal Products, and WHO TRS No. 1016 Annex 2.

Software & Data Management

While the CHOZN® CHO K1 itself is a biological entity and not software-driven, its deployment is fully supported by Merck’s integrated digital bioprocess ecosystem. Users gain access to the CHOZN® Digital Toolkit—a secure, cloud-accessible portal containing SOP templates, batch record templates aligned with ALCOA+ principles, and electronic audit trail–enabled documentation modules compliant with FDA 21 CFR Part 11 and EU Annex 11. Raw data from cell banking, viability assays, and productivity screening are structured to interface with common LIMS (e.g., LabVantage, STARLIMS) and MES platforms. Full traceability—from original isolate origin (ATCC CCL-61™ derivative) through MCB expansion history—is embedded in each CoA and digitally archived for ≥15 years.

Applications

• Clinical-stage mAb, bispecific antibody, and Fc-fusion protein production (Phase I–III)
• Platform process development and tech transfer across global manufacturing sites
• Comparative expression studies evaluating promoter strength, vector architecture, or codon optimization strategies
• Process characterization and validation studies, including DoE-based media/feed optimization and scale-down model qualification
• Generation of reference standards and comparability batches during biosimilar development

FAQ

Is CHOZN® CHO K1 supplied as a frozen vial of cells or as a ready-to-thaw working cell bank?
It is supplied as a qualified Working Cell Bank (WCB) in vapor-phase liquid nitrogen cryovials, with full traceability to the cGMP-stored Master Cell Bank.
Does Merck provide technical support for process adaptation and clone screening?
Yes—Merck offers application support packages including protocol optimization, clone selection guidance, and analytical method transfer assistance through its Global Bioprocess Support Team.
Can CHOZN® CHO K1 be used for transient expression?
While optimized for stable pool and clonal line generation, it supports high-efficiency transient transfection (typically >70% transfection efficiency and 100–300 mg/L IgG in 7-day cultures) using linear PEI-based protocols.
What documentation accompanies the cell line shipment?
Each order includes a Certificate of Analysis, Cell Line History Report, STR Profile Report, Mycoplasma Testing Report (per ATCC guidelines), and a Statement of Regulatory Compliance.
Are licensing fees required for commercial manufacturing?
A commercial license agreement is mandatory for GMP manufacturing; academic and preclinical research use is covered under the standard Material Transfer Agreement (MTA).