The FDA expects to approve 10 to 20 cell and gene therapy products a year within the next six years, and is hiring 50 more clinical reviewers to make it happen, the agency announced Jan. 15.

Gene therapy is a technique that modifies a person’s genes to treat or cure diseases, the Food and Drug Administration said. There are 16 approved gene or cellular products. The expected growth in approval rates comes from “a large upswing in the number of investigational new drug applications,” according to the FDA.

Gene therapies can cost hundreds of thousands of dollars for a round...