Clinical trials are aimed at examining the efficacy and safety of new therapeutic substances. They are conducted in accordance with specific principles and with the requirements, exhaustively described in the Polish legal regulations, as well as international regulations. To make sure that all the Polish clinical trials are performed correctly, .special institutions have been called into existence
In clinical trials the key factor is to ensure patients’ safety and that their rights are protected, hence all types of studies must be carried out in keeping with the Good Clinical Practice guidelines, or GCP in short.
The main principles of GCP are as follows:
·       The patients’ wellbeing, their rights and safety are of an overriding importance as to the interests of science or the society
·       Data acquired must be credible and precise.
Patients’ participation in clinical trials is free of charge. All expenses arising from the course of the treatment (the cost of medications, specialistic examinations, medical care) are to be covered by the sponsor of the trials.
 
Benefits to the patients arising from the participation in the trials are as follows:
·      Free-of-charge medical care
·      Free-of-charge series of examinations
·      Free-of-charge access to innovative treatment methods, as of yet inaccessible on the market 
·      An active contribution to medical development
 
Phases of clinical trials
Clinical trials are carried out in four stages (phases). Each and every phase must produce a positive result so that it is possible to proceed to the next phase.
Phase 1
Firstly, the substance is tested for its safety. In a group of couple of dozens of healthy volunteers, factors such as metabolism, absorption, excretion, potential toxicity as well as interaction with other ingested substances (such as food, medications) are investigated.  Upon completion of that stage, it is possible to specify the dose of the examined substance. Trials take place at highly specialist medical centers, mostly operating under pharmaceutical companies or research institutes.
In the case of research into substances used to treat cancer, Phase 1 and Phase 2 are joined, to not expose healthy volunteers to the effects of highly toxic substances. 
Phase 2
At this stage of the trials, it is determined whether the therapeutic is effective within specific group of patients, and whether it is safe for them. It also assessed whether there is any connection between the dose and the effects of the substance, which leads to the determination of the dose administered in subsequent phases of the trials. Safety and efficacy of the examined drug are being assessed at all times. In phase 2, data pertaining to the absorption, metabolism as well as excretion of the drug are subject to detailed assessment, depending on the sex and age. At this stage of the trials, a comparison is made between the effects of the new therapeutics and the placebo, or the drug administered in the treatment of a specific disease. The comparison is made on the basis of the double blind study, which is to ensure the most objective assessment of its effects is provided. In accordance with the method applied, neither the patient nor the investigator knows whether the patient is given a substance which is the subject of the investigation, or a placebo.  The individuals taking part in the trials is randomly selected and consists of a few hundreds of volunteers – including patients suffering from a given disease.
A positive assessment of Phase 2 of the trials is acquired only when the benefit-risk ratio resulting from the administration of given therapeutics is significantly higher.   After receiving such result, it is possible to proceed to the next phase of the trials.
Phase 3
Phase 3 of the clinical trials is aimed at proving the efficacy of the substance examined in the treatment of a given disease. This stage involves an investigation into the relation between the safety of the drug and its efficacy during short-term and long-term use. A group of up to a few thousand of patients take part in the examination, and the duration ranges from one to a couple of years.  Similarly, as it is in case of Phase 2, double-blind method is used as well as a randomization of patients.
Upon a positive completion of Phase 3 of the trials, the drug may be registered and rolled out.
Documentation regarding the drug, submitted to the institution responsible for registering the therapeutic product contains all the data gathered at the time of pre-clinical trials as well as clinical trials, from Phase I to Phase 3. This constitutes a mandatory element of the documentation which might even be a few thousand pages long. In order to precisely specify what type of data should be included in the documentation, drug manufacturers, before commencing the clinical trial, consult it with drug regulatory agencies (FDA, EMA) in given countries. This allows to accurately derermine the group of patients to whom a given drug can be provided, and it reduces the risk of rejecting the documentation due to significant data omission.
Phase 4
The last phase of clinical trials involves drugs which had been registered and put on the market, drugs which are available for sale. At this stage, it is important to determine whether the drug is safe regarding all indications recommended by the manufacturer, and whether the drug is safe for all groups of patients. In this phase, results acquired in previous phases are additionally verified. In the scope of Phase 4, new indications for already registered drugs are also examined.