Subject (clinical trial participant)

A subject means an individual who participates in a clinical trial, either as recipient of an investigational medicinal product or as a control (Art. 2(2)(17) EU Clinical Trials Regulation 536/2014). The terms "participant" and "trial participant" are increasingly preferred in patient-facing documents and in ICH E6(R3), but "subject" remains the legal term in the Regulation and in FDA regulations. Healthy volunteers in Phase I trials are subjects as much as patients in later phases.

Chapter V of the CTR sets out the protection of subjects: informed consent (Art. 28 to 30), special rules for incapacitated subjects (Art. 31), minors (Art. 32), pregnant or breastfeeding women (Art. 33), emergency situations (Art. 35) and, under national law, other vulnerable groups such as persons in detention or in dependent relationships. Subjects may withdraw at any time without detriment, must be able to contact an independent point of information, and are covered by compensation arrangements (Art. 76).

Every subject is also a data subject under the GDPR. Their identity is known to the investigator site, which acts as controller for source records and holds the pseudonymisation key; the sponsor processes pseudonymised health data as controller for the trial dataset. The two capacities are governed by different rules: withdrawal of consent to participate stops new procedures and data collection, whereas the data protection rights over data already collected are shaped by Art. 58 CTR retention, GCP integrity and the Art. 89 research safeguards. The informed consent form should explain both dimensions clearly.