Pharmacodynamic Studies in Drug Development: What you don’t know can hurt you


Research biopsies involve the collection of tissues for scientific endpoints. In the early phase cancer trials, research biopsies are often used to assess the biological activity of a drug on a molecular level. This is called pharmacodynamics – the study of what a drug does to the body at the molecular or cellular level. Because these research procedures can burden patients but have no value for their disease management, the ethical justification for research biopsies rides on the benefit to future patients through the development of safe and effective drugs.

Working under the premise that accrual of such “knowledge value” requires the publication of findings, we previously reported that only a third of pharmacodynamic studies are published in full. This initial report, published in Clinical Cancer Research, also found that over 60% of participating research oncologists regard reporting quality of pharmacodynamic data to be fair to poor. The August issue of the British Journal of Cancer  reports on the findings of our recent follow up of that study.

In it, we find that reporting quality varies widely between studies.  Many studies do not report methodologies- or results- that would enable readers of such studies to make reliable inferences about the pharmacodynamics findings.  For instance, only 43% of studies reported use of blinding, 38% reported dimensions of tissues used for biopsy analysis, and 62% reported flow of patients through analysis. We also found a preponderance of “positive results,” suggesting possible publication bias.

Together, our two investigations offer a complex picture of publication and reporting quality for PD studies involving nondiagnostic biopsy. Frequent nonpublication and low reporting of basic methodological items suggests room for improvement. However, we did uncover many studies that were well reported, and a large fraction of studies (72%) described ways that PD findings might guide future investigations. In the end, the results of our studies highlight many opportunities for researchers to improve the risk/benefit balance of PD studies by improving the way they are reported.


    title = {Pharmacodynamic Studies in Drug Development: What you don’t know can hurt you},
    journal = {STREAM research},
    author = {GeorginaFreeman},
    address = {Montreal, Canada},
    date = 2013,
    month = sep,
    day = 30,
    url = {}


GeorginaFreeman. "Pharmacodynamic Studies in Drug Development: What you don’t know can hurt you" Web blog post. STREAM research. 30 Sep 2013. Web. 04 Mar 2024. <>


GeorginaFreeman. (2013, Sep 30). Pharmacodynamic Studies in Drug Development: What you don’t know can hurt you [Web log post]. Retrieved from


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