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.
To learn more about investigational drugs, read the AIDSinfo What is an Investigational HIV Drug? fact sheet.
What is KP-1461?
KP-1461 is an investigational drug that has been studied for the treatment of HIV infection.
KP-1461 belongs to a class (group) of HIV drugs called nucleoside reverse transcriptase inhibitors (NRTIs).2 KP-1461, however, does not work like a typical NRTI. Typical NRTIs block an HIV enzyme called reverse transcriptase, which prevents HIV RNA from being converted to HIV DNA. (An enzyme is a protein that starts or increases the speed of a chemical reaction.) Preventing the RNA-to-DNA conversion step stops HIV from replicating.
With KP-1461, HIV RNA is still converted to HIV DNA. But while the HIV DNA is being formed, KP-1461 introduces mutations into the DNA. These mutations harm HIV rather than help it to survive. In theory, KP-1461 causes so many mutations to build up in HIV over time that the virus cannot continue to live and cannot multiply in the body. This process of stimulating mutations in HIV at a higher-than-normal rate to ultimately stop HIV from multiplying is called “viral decay acceleration.” And KP-1461 is known as a “viral decay accelerator.”3-6
KP-1461 is also a prodrug, which means that it is an inactive drug. Once taken, a prodrug does not work until the body converts it into an active form. In the body, KP-1461 is first converted to KP-1212. Then, once KP-1212 is inside cells, it is converted to an active form called KP-1212-TP.5,6
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.7
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.7
In most cases, an investigational drug must be proven effective and must show continued safety 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.7
In what phase of testing is KP-1461?
KP-1461 has been studied in a Phase II clinical trial.2
What are some studies on KP-1461?
Study Names: KP-1461-201; NCT00504452
Phase: IIa
Location: United States and Puerto Rico
Participants:
- HIV-infected adults who had taken HIV medicines before entering the study (also called treatment-experienced).
- Participants had received prior antiretroviral therapy (ART) that did not control their viral load (the amount of HIV in a blood sample) and/or had drug resistance to multiple classes of HIV medicines. (Drug resistance is when a person’s HIV mutates [changes form] and becomes insensitive to a drug that was previously effective.)
- Participants were required to be off ART for at least 16 weeks before starting the study.
Purpose: The purpose of this study was to look at the safety and effectiveness of KP-1461.
Study Design: Participants took 1600 mg of KP-1461 orally and twice daily for 124 days. KP-1461 was given without any other HIV medicines (also known as monotherapy).
Results:
- In this study, 124 days of KP-1461 monotherapy did not have antiviral activity in treatment-experienced participants. In other words, participants’ viral load levels did not significantly change from the beginning of the study to the end of the study.
- A second analysis on whether KP-1461 worked the way it was predicted to work confirmed that KP-1461 indeed introduced certain types of mutations in participants’ HIV. And in terms of those mutations, participants who took KP-1461 had more of them than the participants who did not take KP-1461.
- Researchers noted that a possible reason for why KP-1461 did not reduce participants’ viral loads was that treatment time was not long enough. Researchers also noted that an improved KP-1461 formulation may be needed to improve treatment results.
- In terms of safety, most side effects that occurred in the study were mild to moderate in severity. There were no reports of serious side effects with KP-1461. Two participants stopped KP-1461 because of side effects. One participant stopped treatment because of headache and nausea, and another participant stopped treatment because of inflammation of the esophagus.4,8,9
What side effects might KP-1461 cause?
In the Phase IIa study (KP-1461-201) discussed under the previous question, the majority of participants reported at least one side effect. Most of the reported side effects were mild to moderate in severity. Half of participants experienced at least one side effect that was considered possibly related to KP-1461. The most frequently reported KP-1461-related side effects were gastrointestinal (GI) disorders and nervous system disorders. Nausea was the most common GI disorder. Dizziness and impaired taste were the most common nervous system disorders.4
Because KP-1461 is still being studied, information on possible side effects of the drug is not complete. As testing of KP-1461 continues, additional information on possible side effects will be gathered.
Where can I get more information about clinical trials studying KP-1461?
More information about KP-1461-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 KP-1461. How can I find more information about participating in a clinical trial?
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.7
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.
References
- United States National Library of Medicine. ChemIDplus Advanced. Available at: http://chem.sis.nlm.nih.gov/chemidplus/rn/815588-85-3. Last accessed on January 14, 2016.
- National Institute of Allergy and Infectious Diseases (NIAID). NIAID ChemDB, HIV Drugs in Development. Available at: http://chemdb.niaid.nih.gov/DrugDevelopmentHIV.aspx. Last accessed on January 14, 2016.
- Evans D. KP-1461: A Novel Anti-HIV Drug in Limbo? BETA. 2010 Winter-Spring; 22(2): 9-11. Available at: http://sfaf.org/hiv-info/hot-topics/beta/beta_2010_winspr_drugwatch.pdf. Last accessed on January 14, 2016.
- Hicks C, Clay P, Redfield R, et al. Safety, Tolerability, and Efficacy of KP-1461 as Monotherapy for 124 Days in Antiretroviral-Experienced, HIV Type 1-Infected Subjects. AIDS Res Hum Retroviruses. 2013 Feb; 29(2): 250–255. Available at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3552433/. Last accessed on January 14, 2016.
- James JS. New Kind of Antiretroviral, KP-1461; Clinical Trial Recruiting. Interview with Stephen Becker, M.D. AIDS Treat News. 2007 Jul-Sep; 423: 3-7. Available at: http://www.aidsnews.org/2007/10/kp-1461.html. Last accessed on January 14, 2016.
- Murakami E, Basavapathruni A, Bradley W, and Anderson KS. Mechanism of action of a novel viral mutagenic covert nucleotide: Molecular interactions with HIV-1 reverse transcriptase and host cell
DNA polymerases. Antiviral Res. 2005 Jul; 67(1): 10-7. Available at: http://www.vdapharma.com/s/2005-Mechanistic-studies-on-KP-1212.pdf. Last accessed on January 14, 2016.
- National Institutes of Health (NIH). NIH Clinical Research Trials and You. Available at: http://www.nih.gov/health-information/nih-clinical-research-trials-you. Last accessed on January 14, 2016.
- Mullins JI, Heath L, Hughes JP, et al. Mutation of HIV-1 Genomes in a Clinical Population Treated with the Mutagenic Nucleoside KP1461. PLoS One. 2011; 6(1): e15135. Available at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3021505/. Last accessed on January 14, 2016.
- Koronis Pharmaceuticals. An Open-Label, Multicenter, Mechanism Validation Study to Evaluate the Safety, Efficacy and Tolerability of KP-1461 as Monotherapy for 124 Days in Antiretroviral-experienced, HIV-1-infected Subjects. In: ClinicalTrials.gov. Bethesda (MD): National Library of Medicine (US). Registered on July 18, 2007. NLM Identifier: NCT00504452. Available at: https://www.clinicaltrials.gov/ct2/show/NCT00504452. Last accessed on January 14, 2016.
Last Reviewed: January 14, 2016
