Phase 0, including microdosing approaches: Applying the Three Rs and increasing the efficiency of human drug development

Tal Burt, Le Thuy Vuong, Elizabeth Baker, Graeme C. Young, A. Daniel McCartt, Mats Bergstrom, Yuichi Sugiyama and Robert Combes

Phase 0 approaches, including microdosing, involve the use of sub-therapeutic exposures to the tested drugs, thus enabling safer, more-relevant, quicker and cheaper first-in-human (FIH) testing. These approaches also have considerable potential to limit the use of animals in human drug development. Recent years have witnessed progress in applications, methodology, operations, and drug development culture. Advances in applications saw an expansion in therapeutic areas, developmental scenarios and scientific objectives, in, for example, protein drug development and paediatric drug development. In the operational area, the increased sensitivity of Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS), expansion of the utility of Positron Emission Tomography (PET) imaging, and the introduction of Cavity Ring-Down Spectroscopy (CRDS), have led to the increased accessibility and utility of Phase 0 approaches, while reducing costs and exposure to radioactivity. PET has extended the application of microdosing, from its use as a predominant tool to record pharmacokinetics, to a method for recording target expression and target engagement, as well as cellular and tissue responses. Advances in methodology include adaptive Phase 0/Phase 1 designs, cassette and cocktail microdosing, and Intra-Target Microdosing (ITM), as well as novel modelling opportunities and simulations. Importantly, these methodologies increase the predictive power of extrapolation from microdose to therapeutic level exposures. However, possibly the most challenging domain in which progress has been made, is the culture of drug development. One of the main potential values of Phase 0 approaches is the opportunity to terminate development early, thus not only applying the principle of ‘kill-early-kill-cheap’ to enhance the efficiency of drug development, but also obviating the need for the full package of animal testing required for therapeutic level Phase 1 studies. Finally, we list developmental scenarios that utilised Phase 0 approaches in novel drug development.

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The Best Model for Humans is Human — How to Accelerate Early Drug Development Safely

Mark Seymour

Traditionally, the choice of which candidate compounds to take forward into development has been based on pre-clinical data. However, lack of predictivity of the human clinical situation in the models used has led to poor decision-making, and the later in the development process that such mistakes are realised, the more costly and time-consuming it is to correct them. Furthermore, compounds that may have made perfectly good drugs, have been dropped due to poor pharmacokinetics in animal models. Accelerator mass spectrometry (AMS) is an ultra-sensitive detection technique that can be used to quantify carbon-14. By administering very small amounts of 14C-labelled compounds, AMS can be used to obtain human clinical data very early in the drug development process. Such studies: a) can be helpful in understanding human pharmacokinetics using microdosing; b) can provide early human metabolism information, to validate the choice of animal species used in pre-clinical safety testing and identify unique or disproportionate human metabolites during Phase 1; and c) can provide fundamental human pharmacokinetic data, including absolute bioavailability, by facilitating a scientifically optimal and cost-effective study design. The provision of these clinical insights at the earliest possible opportunity can lead to improved decision-making, and therefore can reduce the time and cost involved in the drug development process.
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