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.
INCB-9471 is an investigational drug that is being studied for the treatment of HIV infection.
INCB-9471 belongs to a class (group) of HIV drugs called entry and fusion inhibitors.2 Entry and fusion inhibitors block HIV from getting into and infecting certain cells of the immune system. This prevents HIV from multiplying and can reduce the amount of HIV in the body.
INCB-9471 works by attaching to one of two proteins on the surface of the immune cells. These proteins are called the CCR5 and CXCR4 coreceptors. INCB-9471 attaches to the CCR5 coreceptor. When INCB-9471 attaches to the CCR5 coreceptor, certain strains of HIV—called R5-tropic virus—cannot attach to, enter, or infect the cell.3
Research may prove that INCB-9471 is a safe and effective option for treating people with R5-tropic virus, including those for whom other entry and fusion inhibitors, such as maraviroc (brand name: Selzentry), are not working.4
Clinical trials are conducted in phases. Each phase has a different purpose and helps researchers answer different questions.5
In most cases, an investigational drug must be proven safe and effective in a Phase III clinical trial to be considered for approval by FDA for sale in the United States. Some drugs go through FDA’s accelerated approval process and are approved before a Phase III clinical trial is complete. After a drug is approved by 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.5
INCB-9471 has been studied in Phase II clinical trials.2 In 2008, the company developing INCB-9471 announced that it was no longer actively studying INCB-9471 and was seeking a partner company to develop the drug.3
In a 14-day Phase IIa study, INCB-9471 taken once daily was compared with placebo in HIV-infected adults who had R5-tropic virus. (A placebo is an inactive drug that is identical in appearance to the active drug being studied.) Some of participants had never taken HIV medicines before entering the study (also called treatment-naive), and others had taken HIV medicines previously (also called treatment-experienced). The treatment-experienced adults had been off therapy for at least 3 months. In this study, INCB-9471 was given alone without any other HIV medicines (also known as monotherapy).6,7
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. (Viral load is the amount of HIV in a blood sample.) In terms of safety, INCB-9471 was generally safe. No serious side effects or study drop-outs were reported.7,8
An additional Phase II study of INCB-9471 in treatment-naive and treatment-experienced adults with R5-tropic HIV has been completed. In this study, three different strengths of once-daily INCB-9471 monotherapy were compared with placebo. Results indicated that at the two higher strengths studied, INCB-9471 had significant antiviral activity.9
In the first study discussed under the previous question, which was a 14-day Phase IIa study of INCB-9471 in HIV-infected adults, INCB-9471 was generally considered safe. Some mild side effects that occurred that might be related to INCB-9471 treatment included constipation, diarrhea, nausea, headache, hiccups and rash.6-8
In previous studies of INCB-9471 in healthy study participants, some common side effects that occurred were headache, diarrhea, sore throat, and cold symptoms.10,11
Because INCB-9471 is still being studied, information on possible side effects of the drug is not complete. As testing of INCB-9471 continues, additional information on possible side effects will be gathered.
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.
Participating in a clinical trial can provide benefits. For example, a volunteer participant can benefit from new research treatments before they are widely available. Participants also receive regular and careful medical attention from a research team that includes doctors and other health professionals. However, clinical trials may also involve risks of varying degrees, such as unpleasant, serious, or even life-threatening side effects from the treatment being studied.5
Your health care provider can help you decide whether participating in a clinical trial is right for you. For more information, visit NIH Clinical Research Trials and You.
Last Reviewed: October 26, 2014