Competitiveness in follow-on drug R&D: a race or imitation?

The development of 'follow on' or 'me too' drugs - generally defined as a drug with a similar chemical structure or the same mechanism of action as a drug that is already marketed - has attracted contrasting views. Some have argued that follow-on drugs often provide useful alternative or enhanced therapeutic options for particular patients or patient subpopulations, as well as introducing price competition. Others, however, consider that the development of such drugs is duplicative and that the resources needed would be better directed elsewhere. Implicit in some of this criticism is the notion that the development of me-too drugs is undertaken after a first-in-class drug has made it to market and proved commercially successful. In this Perspective, using analysis of development and patent filing histories of entrants to new drug classes in the past five decades, we provide new evidence that the development of multiple new drugs in a given class is better characterized as a race, rather than the imitation of successful products.