Progressive approval: a proposal for a new regulatory pathway for regenerative medicine.

To stimulate a broad discussion between academics, practicing physicians, corporate managers, and members of the regulatory community, we describe a proposal for a new regulatory pathway for human cell- and tissue-based products. The new components of the pathway are intended to accelerate patient access to a wide array of novel therapeutics, strengthen R&D infrastructure, and expand patient numbers and time lines for efficacy testing through a transparent and publicly accessible website for real-time reporting of outcome data and 5- to 10-year, long-term follow-up.