What is a clinical trial?

A clinical trial is the experimental evaluation of a product, substance, drug, diagnostic or therapeutic technique that, through its application in human beings, tries to evaluate both efficacy and safety. The people that take part in clinical trials do so voluntarily.

The clinical trials in oncology are designed to test new kinds of treatments, diagnoses, prevention, management of symptoms or secondary effects originating from the treatment.

When does a clinical trial begin?

Before being tested in humans, scientists analyze the molecule “in vitro”, meaning in the laboratory, which lead then to the next step, analysis “in vivo”, which is in animals. This stage is crucial for guaranteeing the safety of the new compound; these steps are called “preclinical investigation”.

Which are the different phases of a clinical trial?

Once the pre-clinical phase is complete, we enter ‘clinical investigation’ meaning in humans. A clinical trial is built up of different phases, the principal objective being to improve the therapeutic options in patients with cancer.

Phase I: This is the first stage carried out in humans; its objective is to demonstrate the safety of the compound. These studies tend to be quite small in numbers.

Phase II: The objective of this second phase is to provide preliminary information on the efficacy of a product and to establish a dose to take forward. These are exploratory therapeutic studies with a larger number of patients, around 100.

Phase III: During this phase, the efficacy and safety of the compound being investigated are evaluated under normal conditions of use; they are often compared to other available therapeutic alternatives in the indication. Phase III studies normally are much larger and are of a long duration

Phase IV: This phase takes place after approval at the behest of the regulatory authorities.

How to measure Response Rate in solid tumors?

The World Health Organization established in 1979 the first criteria for evaluating Response Rate in solid tumors. Some years later, in the year 2000, the “Response Evaluation Criteria In Solid Tumors”, the RECIST criteria, was published.

The definition of response according to RECIST:

  • Complete Response: all lesions disappear.
  • Partial Response: a decrease of at least 30% in tumor size.
  • Disease Progression: an increase of at least 20% tumor size, or the appearance of new lesions.
  • Stable Disease: Neither a sufficient decrease in tumor size to be considered Partial Response, nor a sufficient increase in the size of the tumor to be considered Disease Progression is obtained.
  • Objective Response Rate: Complete Response plus (+) Partial Response. The percentage of patients that achieve a reduction in the size of the tumor of 30% or more (patients that have reached a Complete or Partial Response).

La información aquí contenida tiene carácter meramente divulgativo y no pretenden sustituir en ningún caso la consulta del facultativo. En caso de duda o de presentar síntomas, consulte siempre a un profesional médico.

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