First-in-human clinical trials

First-in-human clinical trials, also known as Phase 1 trials, represent the critical first step in testing a new drug, vaccine, or medical device in people. Following extensive preclinical research in laboratories and animal models, this phase is designed primarily to assess the safety of the new intervention. The core objectives are to determine a safe dosage range, identify potential side effects, and understand how the human body processes the substance—a field of study known as pharmacokinetics, which examines its absorption, distribution, metabolism, and excretion (ADME).

These trials typically involve a small number of participants, often between 20 and 100. In many cases, these are healthy volunteers who are compensated for their time and the risks involved. However, for treatments intended for serious or life-threatening diseases, such as advanced cancers, the first participants may be patients who have exhausted all other standard treatment options. The study design often involves dose-escalation, where the first small group receives a very low dose of the intervention, and subsequent groups receive progressively higher doses only after the safety of the lower dose has been confirmed. Participants are monitored intensively for any adverse reactions.

First-in-human trials are a pivotal transition point in the drug development lifecycle, bridging the gap between preclinical discovery and later-stage clinical evaluation. Before a trial can begin, developers must submit a comprehensive data package from their laboratory and animal studies to a regulatory authority, such as the U.S. Food and Drug Administration (FDA) or the European Medicines Agency (EMA). This application, known as an Investigational New Drug (IND) application in the U.S., must provide sufficient evidence to suggest the intervention is reasonably safe for initial human testing. If the data from a Phase 1 trial are favorable, the intervention can proceed to Phase 2 trials, which focus on evaluating its effectiveness in a larger group of patients with the target condition.

The significance of first-in-human trials cannot be overstated; they are the gateway through which all new medicines must pass to reach the public. This stage carries inherent risks, as the effects of a new compound in humans can never be predicted with absolute certainty from animal studies. Consequently, these trials are governed by strict ethical principles and rigorous regulatory oversight. The process of informed consent is paramount, ensuring that participants fully understand the potential risks, benefits, and the experimental nature of the treatment. Independent ethics committees or Institutional Review Boards (IRBs) must approve and monitor the trial to safeguard participant welfare. While a high percentage of investigational drugs fail to demonstrate an acceptable safety profile in Phase 1, these trials are an essential and unavoidable step in the scientific process of developing safer and more effective medical treatments.