What you need to know about clinical trials

The patient at the centre of clinical trials

Patients are at the heart of clinical research because their participation is essential to generate medical knowledge, improve existing treatments and develop new therapeutic options. The patients’ well-being is the primary focus of clinical trials, and their contribution plays a crucial role in the progress of medical science


Clinical research is the key to new treatments

Clinical research refers to all scientific research that is carried out on human subjects, with the aim of expanding knowledge about diseases and developing new diagnostic methods and treatments to improve healthcare for patients.  

Through research, we can create new drugs, technologies, procedures, systems, tools and resources to apply in our daily lives.   

The key role of clinical trials for patients and society

Clinical trials are directly related to clinical research, without them we would not be able to test or confirm hypotheses put forward during research.  


A clinical trial is defined as a form of research in which the performance of a new treatment or medicine against a specific disease is studied in patients in a safe and controlled environment. Currently, clinical trials provide knowledge of the drug related to: 

  • Efficacy: is it more effective than other drugs used for the same pathology?  
  • Safety: what is the tolerance level of patients, does it produce any toxicity?   
  • Dose range: what is the optimal amount to achieve the best risk-benefit ratio for patients?  


Typically, to test these three aspects, the investigational drug is compared with the marketed drug, and patients are usually assigned to two different groups within the trial:  


  • Group A (control): will receive conventional treatment.  
  • Group B (experimental): given the new treatment 


Participation in a clinical trial is voluntary and all relevant aspects of the study will always be explained to the patient in the informed consent form. The patient is free to leave the trial at any time, for any reason, without further explanation.   


Each of the medicines and treatments we currently use have undergone several clinical trials prior to approval, which provides confidence and potential benefits for patients, such as the opportunity to access novel treatments and receive specialised care tailored to their situation. 

Different trials, different ways forward

There are two main types of clinical trials, observational and interventional (each has its own subtypes, you can read more here):  

  • Observational: through these studies, researchers observe and analyse how routine clinical practice develops, without intervening or establishing any specific treatments. 
  • Interventional: these trials establish treatments and measurement variables defined in protocol that compares the behaviour of two drugs between two groups of patients. This is the case of the aboce mentioned group A and B, where two drugs are compared for the same pathology. 

The type of clinical trial used will be determined by the specific characteristics of each case. The different studies generate valuable information that promotes the progress of clinical research by providing substantial scientific evidence of the efficacy, safety and effectiveness of various therapies and medical procedures. 

How many phases are there in a clinical trial?

Regulatory authorities, such as the FDA (Food and Drug Administration), require that the medicine has undergone animal testing before conducting human clinical trials. Once preclinical studies are completed and if the treatment shows continued promise, it moves on to subsequent phases of development.  

Once the pre-clinical phase is completed, clinical trials consist of four stages, each of which aims to answer specific questions and, if the drug is safe, progresses from one stage to the next: 

  • In phase I, the drug is used in patients for the first time and the objective s to assess safety, optimal dose and efficacy. Typically, 10 to 30 patients participate in this phase. Thanks to advances in clinical oncology research, therapies are being developed that specifically target tumour cells, in contrast to the “classical chemotherapy” approach, which affects all cells in the body. These new therapies aim to identify and selectively target cancer cells, which could result in more effective treatments with fewer side effects for patients.  
  • Phase II tests the efficacy of the drug on a specific type of cancer, as well as its safety in a larger group of patients (around 100 participants). The duration of this phase is estimated at three years, as toxicities and the incidence of side effects are also being studied. The clinical benefit will vary depending on the particularities of the disease and the proposed treatment goals, which may include: 
  1. Improve the patient’s quality of life.
  2. Increased life expectancy compared to life expectancy without treatment.
  3. Demonstration of inhibition of tumour growth or a prolonged period before tumour re-growth.  
  • Phase III compares the efficacy and safety of the new drug with the conventional treatment. The main objective is to show variations in the survival rate of participants or in the time to disease progression. This phase, which can last from 3 to 10 years, involves the participation of a variable number of individuals, ranging from 100 to several thousand participants. If the drug proves effective against the disease, it will be submitted to regulatory authorities for approval. 
  • Phase IV is distinguished by the approval of the medicine by regulatory agencies and the start of its commercialization process. During this phase, the main objective is to gather additional information on the use of the medicine in the context of routine clinical practice. Potential new indications are explored, long-term efficacy is assessed, and previously undetected adverse effects are identified. These studies are observational in nature and are maintained under drug surveillance for a prolonged period of time, and may be extended for as long as the product is available on the market.    

The clinical trial phases ensure the efficacy and safety of treatments before they are marketed, generating confidence and potential benefits for patients, such as the opportunity to access innovative therapies or receive specialised care. 

Reasons to consider participating in a clinical trial

Having understood the process from hypothesis formulation to the commercialization of a new drug, it is important to understand the reasons why patients should consider participating in a clinical trial.  

The opportunity to receive innovative treatments before they are commercialized.   

Prior to Phase IV, the only way to access research treatments is through clinical trials. Benefiting from these therapies may be advantageous for patients with specific disease profiles. In certain situations, it may represent an opportunity when there are no treatment options available or when conventional treatments have not been effective. Even after the end of the clinical trial, there is a possibility that patients may continue to receive the researched treatment if it is benefitial to their conditions

  • Comprehensive information on the patient’s disease and health status   

Research provides us with information about various aspects of a disease, such as prevention strategies, diagnostic methods and their impact on quality of life.    

  • Benefit from regular monitoring and evaluation by medical staff.  

Clinical trials are designed to minimise patient risk and to fully assess the effectiveness of treatment. As a result, participants in a clinical trial are likely to receive regular medical care.  

  • Participating in clinical research offers the opportunity to contribute to scientific progress and save lives.

Patients participating in clinical trials is the foundation for all clinical advances and treatments available today. The results obtained will not only benefit the individuals who participate in them, but will also have a positive impact on other patients with similar diseases, generating a significant impact on society and medical research. 

Access innovative treatments through our clinical trial finder