We might not associate the jazz queen Ella Fitzgerald with 21st-century gene-based therapies, but the First Lady of Song was on to something back in 1939 when she sang “’T’Ain’t What You Do (It’s the Way That You Do It).” Although demonstrating the safety and efficacy of gene-based therapies in rigorous clinical trials is essential for gaining product approval from regulators, doing the bare minimum is insufficient. The way that such products are produced also matters. Manufacturing processes and protocols…