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 INCB-9471?
INCB-9471 is an investigational drug for the treatment of HIV infection.
- INCB-9471 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.
- INCB-9471 is a small molecule that specifically binds to the CCR5 coreceptor located on the surface of certain immune cells, such as CD4 cells. When INCB-9471 binds to the CCR5 coreceptor, certain types of HIV (R5-tropic virus) cannot bind to, enter, or infect the immune cell.
- INCB-9471 binds to the CCR5 coreceptor at a location different than that used by other small molecule CCR5 inhibitors, such as maraviroc (brand name: Selzentry). This binding difference means that someone who develops drug resistance to maraviroc may not have cross resistance to INCB-9471.
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 INCB-9471?
INCB-9471 has been studied in Phase II clinical trials.
What have recent studies shown about INCB-9471?
In a Phase II study, INCB-9471 (taken once daily) was compared with placebo in HIV-infected, treatment-naive and treatment-experienced adults. (The treatment-experienced adults had been off therapy for at least 3 months.) Study participants included only those individuals who were shown to have R5-tropic virus. 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 being given to help control a participant’s HIV infection.)
In this study, INCB-9471 showed substantial antiviral activity against R5-tropic HIV. Prolonged anti-HIV activity was apparent, with viral load suppression continuing 2 weeks past the last dose. In terms of safety, INCB-9471 was generally safe and well tolerated.
More information on testing of INCB-9471 is available from these sources:
- INCB-9471 study results presented at the 4th IAS Conference on HIV Pathogenesis, Treatment and Prevention, July 22–25, 2007:
- INCB-9471 study results presented at the 15th Conference on Retroviruses and Opportunistic Infections, February 3–6, 2008:
- PubMed abstract:
Where can I get more information about clinical trials studying INCB-9471?
More information about INCB-9471-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 INCB-9471. 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: November 19, 2012
Last Updated: November 19, 2012