The use of adeno-associated viruses (AAVs) as gene therapy vectors is growing, resulting in a pressing need for efficient, reliable AAV analysis methods. Characterizing AAV critical quality attributes (CQAs), such as the abundance of empty or partially filled capsids, is paramount for developing and producing products with high efficacy, low immunogenicity, and low cost. Available methods include analytical ultracentrifugation (AUC)—considered one of the gold standards of AAV analysis technique—and mass photometry—a newer method based on single-particle light scattering. Mass photometry is a fast, low-cost tool that uses little sample and is suitable for environments requiring good manufacturing practices (GMP) compliance. Here, we assess mass photometry’s performance in AAV characterization by using it to analyze a sample of empty AAVs, to measure proportions of empty vs. partially filled vs. full AAVs, to quantify loading in samples ranging from 100% empty to nearly 100% loaded, and to measure samples containing transgenes of different lengths. Comparing to AUC data where appropriate, we find that the two methods give comparable results. Based on its accuracy, precision, measurement capabilities, and practical advantages (e.g., speed and low cost), we conclude that mass photometry is an ideal AAV analysis tool.

Oncolytic viruses (OVs) are a class of viral preparations with selective replication capability in tumor cells and the ability to activate systemic anti-tumor immunity. They have emerged as an important breakthrough in cancer treatment following chemotherapy, targeted therapy, and immune checkpoint inhibitors. This article systematically reviews the developmental trajectory of OVs from the accidental discovery of wild strains to their genetic engineering-based modification and optimization, and subsequently to accelerated clinical translation. It primarily highlights key advances in viral backbone design, immune regulatory gene insertion, and combination therapy strategies. Currently, several OV-based therapeutics have been approved for clinical use worldwide for the treatment of various solid tumors, including melanoma, glioblastoma, and head and neck cancers, demonstrating their extensive potential for broader indication coverage as evidenced by ongoing clinical trials. Although OVs possess unique advantages in their ability to remodel the tumor microenvironment and elicit both local and systemic anti-tumor effects, their clinical application still faces challenges such as limited monotherapy efficacy, barriers to systemic delivery, a lack of precision biomarkers, and issues in large-scale manufacturing and quality control. Looking ahead, by drawing on cutting-edge technologies such as CRISPR-based gene editing, reverse genetics, advanced delivery systems, and multimodal combination therapy, OVs are expected to achieve greater precision and personalization in cancer treatment, thereby promoting their wider application in the management of solid tumors.

PEGylated recombinant human growth hormone (PEG-rhGH) has garnered significant interest in growth hormone research due to its prolonged half-life and improved patient compliance. An accurate evaluation of its biological activity is critical for ensuring the quality of PEG-rhGH-based therapeutics. In this study, we established an in vitro bioactivity assay using a reporter gene method based on the HepG2/IGF-1 cell line. Key assay parameters, including the initial concentration of PEG-rhGH, serial dilution ratios, cell density, and incubation time, were systematically optimized to generate robust dose–response curves. The assay demonstrated high sensitivity, precision, and reproducibility across multiple batches of PEG-rhGH. The validation results showed an excellent correlation with traditional in vivo animal studies and the Nb2-11 cell proliferation assay, highlighting its suitability for quality control. Furthermore, we developed an ion exchange chromatography (IEC) method to separate five positional isomers of PEG-rhGH, revealing significant differences in bioactivity depending on the PEG modification site. This study demonstrates that the optimized reporter gene assay is not only effective for quality control of PEG-rhGH but also serves as a valuable tool for evaluating and optimizing PEGylated long-acting growth hormone therapeutics.