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

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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.

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This project was supported, in part, by a grant from the Pharmaceutical Research and Manufacturers of America (PhRMA). The research, writing and analysis for this article was conducted independently by the authors.

Author information


  1. Joseph A. DiMasi and Laura B. Faden are at the Tufts Center for the Study of Drug Development, Tufts University, 75 Kneeland Street, Boston, Massachusetts 02111, USA.

    • Joseph A. DiMasi
    •  & Laura B. Faden


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Competing interests

The Tufts Center for the Study of Drug Development is partially funded by unrestricted grants from pharmaceutical companies, contract research organizations, trade associations, niche providers and other corporate interests. The principal investigator, J.A.D., has consulted for the pharmaceutical industry and served as an expert witness in litigation involving pharmaceutical firms.

Corresponding author

Correspondence to Joseph A. DiMasi.

Supplementary information

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  1. 1.

    Supplementary information Table S1

    First-in-class* new drugs, second entrants and time to competitive entry