Clinical Trials: Why Participate?

18 Clinical Trials: Why Participate?



Jamila Mwidau, David Chang




KEY POINTS



• A clinical trial is any investigation in human subjects intended to discover or verify the effects of a product, device, or procedure.

• Clinical trials fall into five basic types: prevention, screening, diagnostic, treatment, and quality-of-life trials.

• An intervention is evaluated through preclinical studies and four phases of clinical trials to ensure its safety and efficacy for human subjects.

• Conducting clinical trials at multiple sites improves participant enrollment, ensures a more representative sample, and promotes collegiality.


Introduction


Many of the advances that have been made in medicine can be attributed to the participation of individuals in clinical trials. In 1747, James Lind performed one of the most famous clinical trials. By comparing the effects of various fruits on afflicted sailors, he was able to demonstrate that citrus fruits cured scurvy.


Strictly defined, a clinical trial or study is


any investigation in human subjects intended to discover or verify the clinical, pharmacological, and/or other pharmacodynamic effects of an investigational product(s), and/or to identify any adverse reactions to an investigational product(s), and/or to study absorption, distribution, metabolism, and excretion of an investigational product(s) with the object of ascertaining its safety and/or efficacy.1


Although this definition specifically addresses pharmacologic agents, clinical trials may also include surgical procedures, diagnostic tests, and medical devices, with the intent to discover or verify safety and/or efficacy.


The strength of the conclusions from any study is dependent on the quality of the scientific approach and the principles used during the trial. For instance, surgical trials are particularly prone to operator bias because of the implications for patient referrals and the surgeon’s reputation. Furthermore, elderly patients are often excluded from clinical trials, and this could affect the outcome of a trial. Although the elderly make up only 14% of the population, they consume more than one third of all drugs. There are other types of clinical research (e.g., case studies), but the clinical trial is viewed as the strongest source of evidence to support safety and efficacy statements. The clinical trial is an experiment in which the conditions are specified in a detailed document called the protocol. This detailed document allows the use of scientific methods to analyze the effects of the treatment.



Types of Clinical Trials


Several types of clinical trials can be conducted, depending on the goal of the study. These types are outlined below.


Prevention trials find better ways to prevent disease in people who have never had the disease or to prevent a disease from returning. The approaches tested in these trials may include medicines, vitamins, vaccines, minerals, and lifestyle changes.

Screening trials test the best way to detect certain diseases or health conditions.

Diagnostic trials are conducted to find better tests or procedures for diagnosing a particular disease or condition. Diagnostic trials usually include people who have signs or symptoms of the disease or condition being studied.

Treatment trials test new treatments, new combinations of drugs, or new approaches to surgery or radiation therapy.

Quality-of-life trials (or supportive care trials) explore ways to improve comfort and quality of life for individuals with a chronic illness.


Phases of a Clinical Trial


Clinical trials are traditionally classified into preclinical trials and four phases, although it is important to note that precise distinctions between the phases are not always possible in practice. Each phase of development leads to a greater understanding of the attributes and uses or indications of the compound or treatment.


The phases of a clinical trial are described in detail in Table 18-1. Briefly, phase 0 trials follow preclinical trials to look at dosing in humans and to speed up the development of a new intervention. Phase I trials are the first step in evaluating whether a new therapy is safe as administered. Phase II trials focus on how a given therapy may affect a specific group of participants for whom the therapy is recommended. Phases I and II usually occur with the help of healthy volunteers. Phase III trials are randomized trials that compare a new therapy with the present standard therapy or placebo therapy (a pill or procedure that does not include active ingredients). However, most cancer trials do not use placebos. Most drugs are not released to the public for general use by the Federal Drug Agency (FDA) until at last two phase III trials have been completed. Finally, phase IV trials are conducted to study the long-term effectiveness of a therapy and may take several years to complete.


Table 18-1 Clinical Research Phases












Phase Description
Phase 0: Human microdosing (preclinical trials) These studies and are designed to speed up the development of promising drugs or imaging agents by establishing very early on whether the drug or agent behaves in human subjects.
Phase I: Human pharmacology
Determines the metabolic and pharmacologic actions and the maximally tolerated dose. The experimental drug is administered to small numbers of normal human volunteers or to a carefully defined subject population under controlled conditions to obtain preliminary data on drug toleration, pharmacokinetics, and pharmacodynamics.

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May 8, 2017 | Posted by in ONCOLOGY | Comments Off on Clinical Trials: Why Participate?

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