When preclinical research yields a promising drug, a phase 0 trial can be used to determine if it behaves as expected when administered to a human. The focus is on how the body processes the drug and what effects it has on the body. The doses are very small and only a few are given, so it is very unlikely that the treatment will affect the participant's cancer. The dose and method of administration established by a phase I trial are tested in phase II.
Usually everyone receives the same dose in the same way, but participants can be divided into different groups to try one dose or method with another. Doctors look for different outcomes depending on treatment goals. In many cases, the goal is for participants to live longer after receiving treatment compared to those who did not receive it. However, metrics such as the amount of cancer reduction or improvements in quality of life can also be used.
If a new treatment is found safe in phase I clinical trials, a phase II clinical trial is done to see if it works in certain types of cancer. The benefit doctors seek depends on the purpose of the treatment. It may mean that the cancer shrinks or disappears. Or it could mean that there is a long period when the cancer doesn't grow anymore or that there is a longer period before the cancer comes back.
In some studies, the benefit may be an improvement in quality of life. Many clinical trials seek to see if people receiving the new treatment live longer than most people without treatment. If a phase III clinical trial shows that treatment works well, doctors may start using it with people outside the clinical trial. These clinical trial clinics are usually led by contract research organizations (CROs) that conduct these studies on behalf of pharmaceutical companies or other research researchers.
In these clinical trials, doctors can check if the treatment benefits people as much as it did before. Unlike other phases of clinical trials, there is almost no chance that people participating in phase 0 trials will benefit. Doctors conduct a phase I clinical trial to determine if a new drug, treatment, or combination of treatments is safe for people. Historically, phase II clinical programs have experienced the lowest success rate of the four phases of development.
It is common practice for certain Phase III trials to continue while the regulatory filing is pending with the appropriate regulatory agency. While not mandatory in all cases, it is generally expected that there will be at least two successful phase III trials, demonstrating the safety and effectiveness of a drug, in order to obtain approval from appropriate regulatory agencies, such as the FDA (U.S. (USA) or the EMA (European Union). At the end of Phase 1, results are collected, analyzed and sent to the FDA for permission to proceed to Phase 2 Clinical Trials.
Phase III clinical trial tests treatment that worked well for volunteers in phase II clinical trial. Before starting a phase I trial, the sponsor must submit an investigational new drug application to the FDA detailing preliminary drug data collected from cell models and animal studies. If enough patients benefit from treatment and side effects are not as severe, phase III clinical trials are started. And the care you would receive in a phase IV study is much like what you might expect if you were to receive treatment outside of a trial.
Using a computer to group volunteers prevents research staff from changing clinical trial results. That would mean that there should be no aspects of the study designed to increase compliance over those that would occur in routine clinical practice. .
