What is an investigational drug?
An investigational drug is one that is under study and is not approved by the U.S. Food and Drug Administration (FDA) for sale in the United States. Medical research studies are conducted to evaluate the safety and effectiveness of an investigational drug. These research studies are also called clinical trials. Once an investigational drug has been proven safe and effective in clinical trials, FDA may approve the drug for sale in the United States.
What is cenicriviroc?
Cenicriviroc is an investigational drug for the treatment of HIV infection.
- Cenicriviroc is an investigational anti-HIV drug included in the entry inhibitor drug class.
- Entry inhibitors interfere with the first step in the HIV life cycle—binding and fusion to target cells. By preventing HIV from entering target immune cells, entry inhibitors stop HIV from replicating and reduce the amount of HIV in the blood.
- Cenicriviroc is a specific type of entry inhibitor called a CCR5 antagonist. CCR5 antagonists block the CCR5 coreceptor located on the surface of certain immune cells, such as CD4 cells. By blocking the CCR5 coreceptor, certain types of HIV (R5-tropic virus) cannot bind to, enter, or infect the immune cell.
- Cenicriviroc is also noted to block another receptor known as CCR2. The CCR2 receptor is associated with inflammatory diseases. Potential benefits of CCR2 receptor blockade in HIV-infected patients are being studied.
How are clinical trials of investigational drugs conducted?
Clinical trials are conducted in “phases.” Each phase has a different purpose and helps researchers answer different questions.
Phase I trials: Researchers test an investigational drug in a small group of people (20–80) for the first time. The purpose is to evaluate its safety and identify side effects.
Phase II trials: The investigational drug is administered to a larger group of people (100–300) to determine its effectiveness and to further evaluate its safety.
Phase III trials: The investigational drug is administered to large groups of people (1,000–3,000) to confirm its effectiveness, monitor side effects, compare it with standard or equivalent treatments, and collect information that will allow the investigational drug to be used safely.
An investigational drug must be proven safe and effective in a Phase III clinical trial to be considered for traditional approval by the FDA for sale in the United States. Some drugs go through the FDA’s accelerated approval process and are approved before a Phase III clinical trial is complete. After a drug is approved by the FDA and made available to the public, researchers track its safety in Phase IV trials to seek more information about the drug’s risks, benefits, and optimal use.
In what phase of testing is cenicriviroc?
Cenicriviroc is currently being studied in Phase II clinical trials.
What have recent studies shown about cenicriviroc?
In an early Phase II study, several different strengths of cenicriviroc taken once daily were compared to placebo in treatment-experienced HIV-infected participants. Study participants did not receive additional anti-HIV drugs as part of a background regimen. (A background regimen is a combination of drugs that are not being studied as the investigational drug[s] in the clinical trial, but are given to help control a participant’s HIV infection.) In treatment-experienced adults who had not been previously treated with a CCR5 antagonist, cenicriviroc was effective in reducing viral load at all strengths. Cenicriviroc was also shown to have anti-inflammatory activity. In terms of safety, no serious side effects occurred. The most common side effects were headache, nausea, constipation, diarrhea, and sinusitis.
Additional Phase II studies of cenicriviroc in HIV treatment-naive adults are under way.
More information on Phase II testing of cenicriviroc is available from these sources:
- Cenicriviroc study results presented at the 18th International AIDS Conference, July 18–23, 2010:
- Cenicriviroc study results presented at the 17th Conference on Retroviruses and Opportunistic Infections (CROI), February 16–19, 2010:
- PubMed abstracts:
- Marier JF, Trinh M, Pheng LH, et al. Pharmacokinetics and pharmacodynamics of TBR-652, a novel CCR5 antagonist, in HIV-1-infected, antiretroviral treatment-experienced, CCR5 antagonist-naïve patients. Antimicrob Agents Chemother. 2011 Jun;55(6):2768-74. Epub 2011 Apr 12.
- Klibanov OM, Williams SH, Iler CA. Cenicriviroc, an orally active CCR5 antagonist for the potential treatment of HIV infection. Curr Opin Investig Drugs. 2010 Aug;11(8):940-50.
Where can I get more information about clinical trials studying cenicriviroc?
More information about cenicriviroc-related research studies
is available from the AIDSinfo
database of ClinicalTrials.gov
study summaries. Click on the title of any trial in the list to see the ClinicalTrials.gov
trial summary and more information about the study.
I am interested in participating in a clinical trial of cenicriviroc. How can I find more information about participating in a clinical trial?
Clinical trials involve benefits and risks. Before deciding to participate in a clinical trial, talk to your health care provider. For more information on participating in clinical trials, visit NIH Clinical Research Trials and You
Last Reviewed: December 12, 2012
Last Updated: December 12, 2012