Cell line development is a cornerstone of biopharmaceutical manufacturing, critically influencing product quality, yield, and process efficiency. In the field of gene therapy—particularly therapies based on adeno-associated virus (AAV)—manufacturing remains a major hurdle due to technical complexities and high costs. Current challenges such as limited scalability and batch-to-batch variability continue to constrain clinical accessibility and commercial viability. This talk will highlight the emerging role of AAV stable producer cell lines as a transformative solution to these limitations. By enabling robust, scalable, and cost-effective AAV production, these engineered cell lines hold the potential to significantly reduce manufacturing costs and expand access to life-changing gene therapies worldwide.