Trials By Phase


60429 (32.77%) of all interventional trials does not have registered phase data


Clinical Trials Phases

Clinical research (drug development, diagnostic procedures, new radiotherapy methods, any preventive, diagnostic or therapeutic method), from basic idea to patient bedside classically goes through different steps known as trial phases. This development life cycle is necessary for ethical and administrative reasons.

Early Phase Development

In the early phase of development investigated drug or clinical concept will be examined on a small number of patients. Those development phases are known as phase 0, phase 1 (phase I) and phase 2 (phase II).

Phase 0 Trials

An exploratory also is known as phase 0. That phase of a trial was introduced as a mechanism to enhance and accelerate the overall process of new oncologic drug development. The performance of a phase 0 study allows investigators to evaluate and understand the pharmacokinetic and pharmacodynamic properties of compounds in human subjects before initiation of phase I trials. Knowledge gathered through phase 0 trials helps to better design subsequent phases of research. Phase 0 trials appear to be rare. A number of phase 0 trials may serve as indices of new breakthroughs in clinical research.

Phase 1 (Phase I) Trials

In phase I, new drug or method will be explored on a small number of people, usually around 10. If the investigational intervention is considered safe and preclinical studies did not show toxicity or harmful reaction phase 1 trials may recruit healthy volunteers. In the case of interventions where the serious adverse reaction may occur, those will be examined on a patient that suffers from particular condition (for example advanced or metastatic cancer). The primary goal of phase 1 trial is to collect data about safety, a safe dosage range in the case of medications and identify side effects of a treatment. Data gathered through phase 1 will be used as the basis for further research, usually in phase 2.

Phase 2 (Phase II) Trials

In phase II, the researcher will continue with the exploration of potential toxicity and search for evidence of effectiveness. Results of phase 2 trials sometimes may serve as a surrogate for definitive proof that examined method has good risk / benefit ratio. A number of patients recruited within phase 2 trials are usually from 50 to 100. However, the number can be higher or lower depending on expected difference in effectiveness or incidence of toxicity. Sometimes phase II trials will explore several treatments parallel.

Late Phase Development

If investigated methods or drugs seems safe and effective investigators usually proceeds with further investigation through phase III and eventually phase IV trials.

Phase 3 (Phase III) Trials

Phase 3 trials, also known as pivotal clinical trials, should provide final proof that examined methods are effective with the acceptable profile of unwanted events. In industry, successful phase 3 trials lead to marketing approval of medication or device. The results sometimes may result in medical practice changes. Phase 3 trials are the most important tool in evidence-based medicine. They are costly, with long durations and they have to recruit a large number of patients.

Phase 4 (Phase IV) Trials

Medical research is not perfect. Phase III / 3 trials are based on well-defined population, with clearly defined inclusion and exclusion criteria. If we do not consider investigated condition, usually, the study population is otherwise healthy. In the real world settings, patients rarely conforms to trials strict inclusion or exclusion criteria. Ideally, all approved interventions or drugs should be followed-up for late effects, good or bad. To answer those questions some sponsors and investigators decide to conduct phase 4 / phase IV trials.