A brief survey of first-in-human studies

Experimental Medicine Approaches in Early-Phase CNS Drug Development

Traditionally, Phase 1 clinical trials were largely conducted in healthy normal volunteers and focused on collection of safety, tolerability, and pharmacokinetic data. However, in the CNS therapeutic area, with more drugs failing in later phase development, Phase 1 trials have undergone an evolution that includes incorporation of novel approaches involving novel study designs, inclusion of biomarkers, and early inclusion of patients to improve the pharmacologic understanding of novel CNS-active compounds early in clinical development with the hope of improving success in later phase pivotal trials. In this chapter, the authors will discuss the changing landscape of Phase 1 clinical trials in CNS, including novel trial methodology, inclusion of pharmacodynamic biomarkers, and experimental medicine approaches to inform early decision-making in clinical development.

Phase 1 Clinical Trials of Small Molecules: Evolution and State of the Art

BACKGROUND

Phase 1 studies comprise the first exposure of a promising new chemical entity in healthy volunteers or, when appropriate, in patients. To assure a solid foundation for subsequent drug development, this first step must carefully assess the safety and tolerance of a new compound and often provide some indication of potential effect, so that a safe dose or dose range can be confidently selected for the initial Phase 2 efficacy study in the target patient population.

METHODS

This review was based on a literature search using both Google Scholar and PubMed, dated back to 1970, using search terms including "healthy volunteers", "Phase 1", and "normal volunteers", and also based on the authors' own experience conducting Phase 1 clinical trials. This paper reviews the history of Phase 1 studies of small molecules and their rapid evolution, focusing on the critical single and multiple dose studies, their designs, methodology, use of pharmacokinetic and pharmacodynamic modeling, application of potentially helpful biomarkers, study stopping criteria, and novel study designs.

RESULTS

We advocate for determining the safe dose range of a new compound by conducting careful dose escalation in a well-staffed inpatient setting, defining the maximally tolerated dose (MTD) by reaching the minimally intolerated dose (MID). The dose immediately below the MID is then defined as the MTD. This is best accomplished by using appropriately screened patients for the target indication, as patients in many CNS indications often tolerate doses differently than healthy non-patients. Biomarkers for safety and pharmacodynamic measures can also assist in further defining a safe and potentially effective dose range for subsequent clinical trial phases.

CONCLUSION

Phase 1 studies can yield critical insights into the pharmacology of a new compound in man and offer perhaps the only development period in which the dose range can be safely and thoroughly explored. Phase 1 studies often contain multiple endpoint objectives, the reconciliation of which can present a dilemma for drug developers and study investigators alike, but which can crucially determine whether a compound can survive to the next step in the drug development process.

[Genetically modified regulatory T cells: therapeutic concepts and regulatory aspects]

Adoptive T‑Zelltherapien sind neuartige Konzepte zur Behandlung verschiedener Krankheiten. CAR-T-Zellen sind dabei als Letztlinientherapie für fortgeschrittene B‑Zelllymphome und die B‑Zellleukämie etabliert und zugelassen. TCR-basierte T‑Zellen als Behandlungsoption verschiedener hämatologischer und solider Tumoren befinden sich in der klinischen Entwicklung. Genetisch modifizierte regulatorische T‑Zellen stehen dagegen noch am Anfang ihrer klinischen Entwicklung zur Induktion von Immuntoleranz in einer Vielzahl von Anwendungsgebieten.

In diesem Artikel wird zunächst ein Überblick über die Funktion der regulatorischen T‑Zellen für die Induktion der Immuntoleranz sowie über ihre Rolle im Pathomechanismus bestimmter Immunerkrankungen gegeben und der aktuelle Stand der klinischen Entwicklungen von therapeutischen Ansätzen auf Basis genetisch modifizierter regulatorischer T‑Zellen zusammengefasst. Im Weiteren werden die regulatorisch-wissenschaftlichen Anforderungen und Herausforderungen hinsichtlich Herstellung und Qualitätskontrolle sowie nichtklinischer und klinischer Testung genetisch modifizierter regulatorischer T‑Zellen als Arzneimittel für neuartige Therapien diskutiert.

"In-House" Data on the Outside-A Mobile Health Approach

Mobile health (mHealth) technologies have the potential to capture dense patient data on the background of real-life behavior. Merck & Co., Inc. (Kenilworth, NJ), in collaboration with Koneksa Health, conducted a phase I clinical trial to validate cardiovascular mHealth technologies for concordance with traditional approaches and to establish sensitivity to detect effects of pharmacological intervention. This two-part study enrolled 18 healthy male subjects. Part I, a 5-day study, compared mHealth measures of heart rate (HR) and blood pressure (BP) to those from traditional methods. Hypotheses of similarity, in the clinic and at home, were tested individually for HR, systolic BP, and diastolic BP, at a 2-sided 0.05 alpha level, with a prespecified criterion for similarity being the percentage differences between the 2 measurements within 15%. Part II, a 7-day, 3-period randomized balanced crossover study, evaluated the mHealth technology's ability to detect effects of bisoprolol and salbutamol. Hypotheses that the changes from baseline in HR were greater in the bisoprolol (reduction in HR) and salbutamol (increase in HR) groups compared with no treatment were tested, at a 1-sided 0.05 alpha level. Linear mixed-effects models, Pearson's correlation coefficients, summary statistics, and exploratory plots were applied to analyze the data. The mHealth measures of HR and BP were demonstrated to be similar to those from traditional methods, and sensitive to changes in cardiovascular parameters induced by bisoprolol and salbutamol.

The impact of composite AUC estimates on the prediction of systemic exposure in toxicology experiments

Current toxicity protocols relate measures of systemic exposure (i.e. AUC, C_max) as obtained by non-compartmental analysis to observed toxicity. A complicating factor in this practice is the potential bias in the estimates defining safe drug exposure. Moreover, it prevents the assessment of variability. The objective of the current investigation was therefore (a) to demonstrate the feasibility of applying nonlinear mixed effects modelling for the evaluation of toxicokinetics and (b) to assess the bias and accuracy in summary measures of systemic exposure for each method. Here, simulation scenarios were evaluated, which mimic toxicology protocols in rodents. To ensure differences in pharmacokinetic properties are accounted for, hypothetical drugs with varying disposition properties were considered. Data analysis was performed using non-compartmental methods and nonlinear mixed effects modelling. Exposure levels were expressed as area under the concentration versus time curve (AUC), peak concentrations (C_max) and time above a predefined threshold (TAT). Results were then compared with the reference values to assess the bias and precision of parameter estimates. Higher accuracy and precision were observed for model-based estimates (i.e. AUC, C_max and TAT), irrespective of group or treatment duration, as compared with non-compartmental analysis. Despite the focus of guidelines on establishing safety thresholds for the evaluation of new molecules in humans, current methods neglect uncertainty, lack of precision and bias in parameter estimates. The use of nonlinear mixed effects modelling for the analysis of toxicokinetics provides insight into variability and should be considered for predicting safe exposure in humans.

Designing first-in-human dose of coagulation factors: application of pharmacokinetic allometric scaling

The objectives of this study were to (i) evaluate the predictive performance of pharmacokinetic interspecies scaling of coagulation factors to predict clearance (CL) and (ii) project first-in-human dose based on the predicted human CL. Human CL of nine coagulation factors was predicted using two or three animal species using two methods: (i) CL vs. body weight (simple allometry) and where applicable (ii) the product of CL and brain weight vs. body weight. Based on the predicted human CL, four methods were used to project the first-in-human dose. The predicted pharmacokinetic parameters and the estimated first-in-human dose of coagulation factors were compared with the observed human values obtained from clinical trials. The results of the study indicated that the CL of coagulation factors can be predicted with reasonable accuracy in humans and a good estimate of first-in-human dose can be obtained from the predicted human CL. The suggested methods in this study are not only time and cost-effective but also provide rational alternatives to the somewhat arbitrary dose selection process for coagulation factors often used.

Animal models and conserved processes

BACKGROUND

The concept of conserved processes presents unique opportunities for using nonhuman animal models in biomedical research. However, the concept must be examined in the context that humans and nonhuman animals are evolved, complex, adaptive systems. Given that nonhuman animals are examples of living systems that are differently complex from humans, what does the existence of a conserved gene or process imply for inter-species extrapolation?

METHODS

We surveyed the literature including philosophy of science, biological complexity, conserved processes, evolutionary biology, comparative medicine, anti-neoplastic agents, inhalational anesthetics, and drug development journals in order to determine the value of nonhuman animal models when studying conserved processes.

RESULTS

Evolution through natural selection has employed components and processes both to produce the same outcomes among species but also to generate different functions and traits. Many genes and processes are conserved, but new combinations of these processes or different regulation of the genes involved in these processes have resulted in unique organisms. Further, there is a hierarchy of organization in complex living systems. At some levels, the components are simple systems that can be analyzed by mathematics or the physical sciences, while at other levels the system cannot be fully analyzed by reducing it to a physical system. The study of complex living systems must alternate between focusing on the parts and examining the intact whole organism while taking into account the connections between the two. Systems biology aims for this holism. We examined the actions of inhalational anesthetic agents and anti-neoplastic agents in order to address what the characteristics of complex living systems imply for inter-species extrapolation of traits and responses related to conserved processes.

CONCLUSION

We conclude that even the presence of conserved processes is insufficient for inter-species extrapolation when the trait or response being studied is located at higher levels of organization, is in a different module, or is influenced by other modules. However, when the examination of the conserved process occurs at the same level of organization or in the same module, and hence is subject to study solely by reductionism, then extrapolation is possible.