A global view of comparability concepts.

The concept of comparability of biological products has evolved over the past decade in response to the need to evaluate whether a change in the manufacturing process of a given product by one manufacturer results in a product that cannot be distinguished with regards to safety and efficacy from the product before the change was made. Advances in biology and technology have made it possible to translate this concept into more specific guidance by regulatory agencies in the U.S.A. and Europe. The spectrum of possible changes that might be made in a manufacturing process is very broad, and the factors that must be considered in evaluating the significance of a given change are complex. These points are discussed, and the need for a harmonized approach is stressed.