Treatment of ovarian cancer
Role of clinical trials
Phase I
This represents the first time a new approach has been tried in humans and looks at how safe the new drug is. It answers the following questions:
What is the safe dose range?
What are the side effects?
How does the body cope with the drug?
Does the drug work against the disease?
The first patient enrolled with be given a small dose of the drug. Doses are gradually increased with each patient and the responses carefully monitored. People involved in these trials will have many tests to see how the drug effects the person and the disease and how the body gets rid of the drug.
Phase I trials are typically limited to small numbers, recruiting 30 to 40 patients. Usually these people have advanced cancer and have had all of the available treatments. They may benefit from the new treatment but many will not. Phase I trials can also look at agents that prevent recurrence.
Phase II
Approximately 70% of phase I trials make it to phase II. The aim of phase II trials is to see:
which cancers does the treatment work against
what is the most effective dose
what are the side effects and how to manage them
If the results show that the new treatment might be at least as good as current treatments, or better, it will go on for further evaluation. Phase II trials typically enroll 50 to 100 patients.
Phase 3
Of the 70% of treatments that made phase II, only 33% will go forward to phase III trials. These are designed to compare the new treatment with the best of the currently available treatments. This guarantees that patients receive some kind of treatment. Phase III trials compare:
a new treatment with the current treatment
different doses or ways of giving the current treatment
a new radiotherapy schedule with the current one
Whereas phases I and II are small and often localised, phase 3 trials involve several thousand patients in many different hospitals throughout the world. This increases the available data which increases the statistical significance of the results and makes the results more reliable.
All phase III trials are randomised. This means that patients are divided into at least 2 groups, called arms, at random. Each arm receives a different treatment, for example, one arm will be given the standard treatment and the other the new one. Sometimes the trials are "blinded" so that either the patient, the researcher or both, do not know which patients are receiving which treatment. This helps to keep those involved objective and report actual effects, not hoped for ones.
If the results of a phase III trial are positive, the manufacturer can then licence the new treatment.
Phase IV
Once a new treatment becomes the standard, information is collected from doctors who use it in real-life situations. This is used to assess long term side effects or damaging interactions with other treatments that may not show up during phase III trials. Sometimes it leads to the withdrawal of a licence.
For further details on current trials, things you should consider before enrolling on a trial, and the issues surrounding them click here.