The Nuts and Bolts of Clinical Trials

Most likely as soon as you entered the wide world of HIV and AIDS you began to hear about clinical trials. Clinical trials are how scientists study new therapies and collect information so we can determine whether or not they are beneficial and should be approved for use by everyone. This is a little oversimplified, but in general this is the goal of "trials". If you are considering joining a clinical trial you should feel comfortable asking lots of questions. Most people look into trials because trials provide access to new therapies that are not widely available.


Clinical trials are a way to access new medications without having private insurance. They are the major part of the drug development process. A clinical trial is defined as: A carefully designed and executed investigation of the effects of a drug administered to humans. The goal is to define the clinical benefits and identify toxicity and side effects, of the drug under study.

The U.S. Government, through the Food and Drug Administration (FDA), requires strict testing of all new drugs and vaccines prior to their approval for use as therapeutic agents.

In other words, clinical trials are the way that government licensing agencies collect information about whether a specific drug for a specific disease in fact does what the manufacturer claims that it does. All drugs licensed in the U.S. are required to undergo this process. These trials are scientifically based. If the trial is well-designed, it will answer a specific question or set of questions about specific treatments for diseases.

HIV/AIDS clinical trials normally occur in four phases. But, even before phase I of human testing a lot of work has gone into combining different agents to form a possible effective drug. "Bench" scientists spend endless hours in the laboratory trying out different compounds. Then the compounds are tested on mice and perhaps other laboratory animals before they are ever tried on a human being.

Phase I

Phase I studies examine the safety of the drug being studied, and often determine the highest dose that can be tolerated. Using the blood of human subjects, most of the testing of the drug is done on human cells in a laboratory. These studies usually enroll a small number of subjects and last a short period of time. In this phase, scientists determine the level of toxicity of a given drug, and decide whether or not the drug is safe enough to administer to human beings. {Phase I is for people who have run out of all options including phase III and phase II trials. For example, the first person to ever take Foscarnett (a drug used to treat CMV) was enrolled in phase I of the trials to approve Foscarnett for the treatment of CMV. He was already blind from CMV and wanted to help others who may become afflicted with the disease. He died from the first dose.} However, most of the time in phase I, the drug is not administered to the participant (they just want your blood).

Phase II

Phase II trials assess whether a new drug is effective. These may include testing different doses to find the best tolerated dose with the least side effects. Phase II trials often enroll a larger number of subjects. Phase II studies are a reasonable option for people who have run out of FDA approved treatment choices. By this phase, although researchers are still experimenting with doses, they do know how much will kill you and how much won't. Dosages have been refined to a level that will not harm you. A person who is resistant to approved drugs could potentially benefit from participating in a phase II study.

Phase III

Phase III trials continue to collect information on the drug's effectiveness and side effects and enroll an even larger number of subjects. They can last months to years, and may generate information on the long-range effects of a drug, including side effects as well as benefits. By Phase III, there is general knowledge of the safety, effectiveness and dosages required for a given medication. Phase III trials are a viable option for infected individuals running out of treatment choices. This is true for new drugs under study as well as new "salvage" drug regimens (which may be different combinations and doses of old medications).

When phase III trials are completed, the drug under study can be approved by the FDA for marketing. After drug approval by the FDA, some people in phase III may be offered to participate in phase IV trials.

Phase IV

Phase IV trials are often called post-marketing studies. Post-marketing studies are designed to address any questions about the medication that remain unanswered by collecting long-term data. However, these post-marketing studies, which are the responsibility of the drug companies and are not required by the FDA, are rarely conducted.

Where are Clinical Trials?

Many groups design and conduct HIV clinical trials. The trials are either funded publicly (by the government) or privately. Publicly funded groups that conduct trials include the Community Programs for Clinical Research on AIDS (CPCRA) and the AIDS Clinical Trials Group, which includes both Adult (AACTG) and Pediatric (PACTG) units. The publicly funded groups are supported primarily through the auspices of the National Institutes of Health (NIH). The privately funded groups are mostly contract research organizations (CROs), some of which are funded by drug companies.

The federally funded CPCRA and ACTG have similar goals. These include using scientifically sound methodologies to test drugs or technologies and to evaluate clinical markers in order to find effective treatments for HIV disease and its complications. Both groups primarily conduct phase II and III studies that target undeserved populations in addition to testing approved drugs. When these networks were originally established their participating sites were very different.

Since its inception the CPCRA has conducted its research in primary care settings (e.g., hospitals and clinics) across the nation. The ACTG originally conducted its research at university-based centers but has expanded to include some primary care sites. The original ACTG has split so that the pediatric trials are now separate from the adults: the ACTG coordinates adult trials while the PACTG administers pediatric trials. The ACTG took advantage of their central locations at university-based centers close to lab facilities to focus on early development of new drugs while the CPCRA, located in primary care sites, conducted longer, larger, later-stage studies.

Strategy Trials

Strategy trials, of increasing importance, are those that try to answer questions, regarding treatment approach, as opposed to questions peculiar to a specific therapy. Examples of strategic questions include which drug or drugs to use first and when to change therapies after it is determined that change is necessary. Privately funded clinical trial research is often conducted for a shorter period of time and usually evaluates a single treatment versus a placebo or another drug. These trials may take place at a physician's office, a private company, or a research organization.

Risks and Benefits

Understanding both the risks and the benefits that might occur if one chooses to participate in a clinical trial is of crucial importance. The informed consent process is critical to this understanding. (If you do not understand the consent form of a study that you are considering joining, ask a Treatment Advocate to help you ... or call women alive at 1.800.554.4876). Hopefully, clinical trials will meet the needs of people living with HIV, clinicians, and researchers, and will continue to provide the data that translates into quality clinical care.