Introduction
Clinical trials are a fundamental part of the process for developing new medications and medical devices, ensuring their efficacy and safety before they reach the market.
The Principal Investigator (PI) is at the heart of these trials and is responsible for overseeing the study at the investigative site. However, the PI does not work alone; the sub-Investigator (SI) plays a crucial role in supporting the operational aspects of the trial. This collaboration between the PI and SI is essential for ensuring the quality of the data collected and the safety of the participants [1].
- The Principal Investigator (PI)
The Principal Investigator (PI) plays a central role in managing clinical trials at a specific site, often a hospital or research center.
Typically, a specialist in the disease being studied, the PI must possess substantial clinical research expertise and be trained in Good Clinical Practices (GCP) [2].
Their responsibilities include patient selection, obtaining informed consent, administering experimental treatments, closely monitoring patient progress and ensuring collection of reliable data [1].
The PI is also responsible for reporting adverse events to the sponsor, ensuring participant safety throughout the trial.
The ICH E6(R2) addendum introduces modern approaches such as risk-based monitoring and the use of digital technologies for data collection and transmission. These advancements require PIs to implement robust processes that ensure data integrity and protect participants’ rights.
Additionally, the PI must supervise the research team, including nurses and clinical research associates, to ensure all staff are adequately trained and qualified [2].
Moreover, the PI serves as the primary liaison between the sponsor, the Clinical Research Organization (CRO) and the investigative site, ensuring regulatory compliance and adherence to the study protocol. Their diligence in trial management is crucial for ensuring the credibility of results and participant safety—core pillars of GCP.
As a conclusion, the PI's leadership is essential to the successful execution and ethical conduct of clinical trials at each investigative site [1].
- The Role of the sub-Investigator (SI) in Clinical Trials
Sub-Investigators (SIs), also known as co-investigators or sub-investigators, play an essential role in clinical research under the supervision of the Principal Investigator.
As highlighted in a case published in 2022, Dr. Raza, the SI, participated in both the patient care and the writing of the clinical article, illustrating the multifaceted contributions of SIs in clinical trials: the SI's responsibilities also include recruiting patients, conducting medical exams, administering the treatment under investigation, and collecting data according to the trial protocol. However, the ultimate responsibility for the trial remains with the PI [3].
Typically, the SI is a physician with expertise in the therapeutic area of the clinical trial, just like the PI. They must be formally delegated tasks by the PI and be properly trained to meet the study's requirements.
By sharing the workload and offering additional specialized knowledge, SI complements the PI’s work and helps ensure the smooth execution of the trial.
Their involvement is crucial in managing patient care, ensuring regulatory compliance, and maintaining the quality of the data collected, all while contributing to the overall success of the clinical trial.
Conclusion
Both the Principal Investigator and the sub-Investigator play crucial roles in ensuring the success of the study. While the PI is responsible for the overall management and oversight of the trial, the SI provides invaluable support in executing specific tasks.
The success of a clinical trial, therefore, depends on the effective coordination between these two key figures, ensuring that the protocols are followed and the GCP requirements are met. This collaborative effort helps safeguard the rights and safety of participants, and ultimately, contributes to the reliability of the clinical trial results.
References
[1] Acteurs de la recherche clinique (promoteur, investigateur…)
[2] E6(R2) Good Clinical Practice: Integrated Addendum to ICH E6(R1) | FDA
[3] The Clinical Research Investigator: Clarifying the Misconceptions - ACRP
