The gene therapy era has arrived. So have the challenges.

A landmark regulatory approval has vaulted the cell and gene therapy space to the front of the drug industry’s mind. But speedy progress has also brought forward significant challenges.

Approved for infants with spinal muscular atrophy, Zolgensma is a stunning advancement for a disease that in its most severe form is fatal before age two. In clinical tests, almost all babies given the therapy remained alive and off permanent breathing support.

“The issue is really how do you cover [Zolgensma], not how you say no to it,” said Michael Sherman, the chief medical officer for Harvard Pilgrim Health Care, in an interview with BioPharma Dive on the sidelines of the 2019 BIO conference in Philadelphia. A similar logic applies...