Individualized cell-based therapeutics and gene therapies will become increasingly important to address the variety of molecular defects present in several thousand serious rare diseases. Some of these therapies may be targeted to as many as a few thousand individuals, but others only may be targeted to one or few individuals. Development of these products poses challenges to the scientific community. For example, how do we obtain substantial evidence of effectiveness and adequate evidence of safety for products for rare diseases, particularly diseases where there may be as few as one patient with the disease? How do we ensure manufacturing quality for products intended to treat one or a few patients? These are some of the questions that must be addressed to facilitate development and access to individualized therapeutics. Although notable progress has been made since the passage of the 21st Century Cures Act in the United States, from the regulatory perspective there are still unanswered questions regarding how to best facilitate the development of such individual therapeutics.