Preclinical efficacy studies in investigator brochures: Do they enable risk–benefit assessment?

Human protection policies require favorable risk–benefit judgments prior to launch of clinical trials. For phase I and II trials, evidence for such judgment often stems from preclinical efficacy studies (PCESs). We undertook a systematic investigation of application materials (investigator brochures [IBs]) presented for ethics review for phase I and II trials to assess the content and properties of PCESs contained in them. Using a sample of 109 IBs most recently approved at 3 institutional review boards based at German Medical Faculties between the years 2010–2016, we identified 708 unique PCESs. We then rated all identified PCESs for their reporting on study elements that help to address validity threats, whether they referenced published reports, and the direction of their results. Altogether, the 109 IBs reported on 708 PCESs. Less than 5% of all PCESs described elements essential for reducing validity threats such as randomization, sample size calculation, and blinded outcome assessment. For most PCESs (89%), no reference to a published report was provided. Only 6% of all PCESs reported an outcome demonstrating no effect. For the majority of IBs (82%), all PCESs were described as reporting positive findings. Our results show that most IBs for phase I/II studies did not allow evaluators to systematically appraise the strength of the supporting preclinical findings. The very rare reporting of PCESs that demonstrated no effect raises concerns about potential design or reporting biases. Poor PCES design and reporting thwart risk–benefit evaluation during ethical review of phase I/II studies.Author summary: To make a clinical trial ethical, regulatory agencies and institutional review boards have to judge whether the trial-related benefits (the knowledge gain) outweigh the trial-inherent risks. For early-phase human research, these risk–benefit assessments are often based on evidence from preclinical animal studies reported in so-called “investigator brochures.” However, our analysis shows that the vast majority of such investigator brochures lack sufficient information to systematically appraise the strength of the supporting preclinical findings. Furthermore, the very rare reporting of preclinical efficacy studies that demonstrated no effect raises concerns about potential design and/or reporting biases. The poor preclinical study design and reporting thwarts risk–benefit evaluation during ethical review of early human research. Regulators should develop standards for the design and reporting of preclinical efficacy studies in order to support the conduct of ethical clinical trials.