Establishment of the first Chinese national standard for recombinant nuclease used as a process material in pharmaceutical manufacturing

Lyuyin WangJing Li^*

• National Institutes for Food and Drug Control, Beijing, China

Recombinant nuclease (RSN) is a critical raw material enzyme that is essential for removing host nucleic acids during the production of cell and gene therapy products. However, the lack of standardized quality evaluation methods and reference materials for RSN has led to the poor reliability and comparability of testing results, hindering the standardized development of related industries. To establish the first Chinese national standard for RSN activity and thereby enable the accurate and comparable quantification of enzymatic potency across laboratories and industries, high-purity candidate RSN reference materials were prepared and structurally analyzed via mass spectrometry. A robust enzymatic activity assay using herring sperm DNA as the substrate was optimized and validated in accordance with ICH Q2(R2) guidelines. The assay's specificity, accuracy, and precision were evaluated. A collaborative study involving three laboratories was then conducted to determine the potency value. The assay demonstrated excellent precision (intra-lab coefficient of variation (CV) < 5%, inter-lab CV 2.01%) and accuracy (recovery 90–110%). The candidate material showed high homogeneity and stability. Collaborative testing confirmed the study's statistical consistency (P > 0.05), and the potency was determined to be 518 U/μL. The establishment of this national standard will provide a unified reference for measuring RSN activity, enhance quality control consistency, and support the safe development and production of biopharmaceuticals, including cell and gene therapies. This standard will serve as a critical tool for regulatory evaluation and industrial applications in China.