Background: Regulatory guidelines often recommend pharmacology assessments in early-phase clinical trials with healthy participants, provided the product can be safely administered. This approach typically results in less pharmacokinetic (PK) variability compared to studies involving patients with confounding factors like underlying diseases. However, early-phase clinical studies are sometimes conducted in patients, especially when different effects are expected or when a drug is suspected to have unavoidable toxicity. Methods: This review examined summaries of 166 completed Phase 1 clinical interventional studies involving adult patients (ages 18-64) with results posted on ClinicalTrials.gov from September 2023 to September 2024. Key characteristics of these studies were analyzed. Results: • Gender Distribution: 91% (151 studies) included both male and female patients, 5.4% (9 studies) included only female patients, and 3.6% (6 studies) included only male patients. • Age Range: Older adults were included in 91.6% (152 studies) of the trials. on the other hand, 9% (15 studies) included pediatric population. • Conditions Studied: 66.3% of the studies focused on oncology. Examples of other conditions studied are systemic lupus erythematosus, depression, and Alzheimer’s disease. • Interventions: Placebo was used in 17.5% (29 studies) of the trials, and 42.2% (70 studies) involved biological interventions. Conclusion: Most Phase 1 studies in patients focused on oncology, highlighting the ongoing need for new cancer therapies. Nearly half of the studies involved biological interventions, reflecting a trend towards innovative treatments. The inclusion of older adults underscores their unique physiological responses, aiding in accurate safety and PK assessments. This review highlights trends in study populations and conditions, which may inform future clinical pharmacology evaluations for Phase 1 trials in patients.
