The success of a vaccine, a gene editing design for an untreated disease, or achieving cell engraftment after several attempts, comes from years of accumulated basic science studies, thousands of experiments, and clinical trials. Innumerable steps precede hits in gene and cell therapies before a first-time revelation, and most of them are failures at the time. At the 27th Annual Meeting of the American Society of Gene & Cell Therapy (ASGCT) in Baltimore last week, several groups of scientists presented achievements that years ago looked impossible.