What is a Clinical Trial?
A clinical trial is a prospective, human‐subject study designed to evaluate the safety, pharmacology, and therapeutic value of a medical intervention—drug, biologic, device, diagnostic, or behavioral program—under a pre-approved research protocol. Each trial is registered, independently reviewed by an ethics committee (IRB/IEC), and conducted in accordance with Good Clinical Practice (GCP) guidelines.
Purpose of a Clinical Trial?
Clinical trials provide the highest level of evidence for:
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Safety – cataloguing adverse events, dose-limiting toxicities, and drug–drug interactions.
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Efficacy – quantifying improvements in disease-specific endpoints (e.g., overall survival, HbA1c, PASI-75).
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Optimal Use – refining dosing schedules, combination regimens, and target sub-populations.
These data enable regulatory authorities to decide whether a therapy’s benefits outweigh its risks, and help payers gauge real-world value.
Phase-by-Phase Roadmap
| Phase | Typical Sample Size | Primary Questions | Approx. Duration* |
|
Phase I |
20 – 80 healthy volunteers or patients |
Is it safe? What dose range is tolerable? |
6 – 12 months |
|
Phase II |
100 – 300 patients |
Does it work in the intended disease? |
1 – 2 years |
|
Phase III |
300 – 3,000+ patients, multi-center |
Does it outperform current standard of care? |
2 – 4 years |
|
Phase IV |
Post-approval, thousands in routine practice |
How does it perform long-term or in special populations? |
Ongoing |
*Oncology averages shown; other therapy areas may vary.
Key Players & Oversight Mechanisms
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Sponsor – designs protocol, funds study, and submits data to regulators.
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Principal Investigators (PIs) – ensure protocol adherence and patient safety at each site.
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Data Safety Monitoring Board (DSMB) – conducts interim analyses and can halt the trial for safety or futility.
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Regulators (FDA, EMA, PMDA, etc.) – audit compliance and issue marketing-authorisation decisions.
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Medical Affairs – translate findings into scientific-exchange materials for HCPs and support lifecycle evidence generation.
Impact on Medicine & Market
Well-executed trials can accelerate market entry, command premium reimbursement, and establish a competitive moat via robust outcomes data. Conversely, poorly designed or under-powered studies risk delays, label restrictions, or complete program termination—costing sponsors years and millions of dollars.
Quick Metrics
- Overall probability of success (Phase I → Approval) across all indications: ≈ 8–12 %
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Median global enrolment rate for Phase III oncology studies: ~1.2 patients/site/month
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Adaptive trial designs and real-world data overlays are reducing development timelines by 10–20 % in select therapy areas.
A disciplined clinical-trial program is therefore the bridge between laboratory innovation and day-to-day patient care—transforming hypotheses into evidence-based medicine and defining the future therapeutic landscape.
Glossary
May 16, 2025