Much of the challenge of developing genetic medicines lies in having the right vector to deliver the therapy to the cells within the body where they need to go. 4D Molecular Therapeutics has developed platform technology that generates large numbers of genetically diverse, synthetic adeno-associated viral vectors that have desired characteristics using a process known as directed evolution. It is using these vectors to build a pipeline of genetic medicines across a broad set of conditions. We spoke to Alan Cohen, senior vice president of clinical development and therapeutic area head of pulmonology for 4DMT, about the limitations of existing vectors for genetic medicines, 4DMT’s directed evolution platform technology, and its programs in cystic fibrosis and Fabry disease.