New Injectable Drug for HIV Provides Three-Month Protection in Monkeys: Study
Sat, April 10, 2021

New Injectable Drug for HIV Provides Three-Month Protection in Monkeys: Study


A team of scientists developed an injectable drug that prevents HIV from invading healthy cells. This might provide long-term protection with fewer side effects.

The new injectable drug for HIV was created by scientists at the University of Utah, a US public research university. The drug could be better compared to existing medications for HIV. It might potentially help patients suffering from drug-resistant HIV strains. Because the drug used a D-peptide, it could not degrade inside the body and was ignored by the immune system. They published their findings in the Proceedings of the National Academy of Sciences.

The Global Rates of HIV/AIDS

HIV or human immunodeficiency virus causes acquired immune deficiency syndrome or AIDS. Without management, an HIV-positive individual is at risk of infection. HIV attacks a type of white blood cell critical in immune responses. The CD4 T cell alerts and stimulates other immune cells, such as killer T cells and macrophages. The virus hijacks and kills CD4 T cells, and if their numbers dwindle significantly, the immune system loses its ability to notify immune cells of infections. Bacteria, fungi, parasites, and other viruses can invade conveniently. Thus, most people with HIV are prone to tuberculosis (TB), especially those with latent TB.

According to Our World in Data, an online source of research data, as of 2017, the death rates due to HIV were 17.28 per 100,000 in people aged 15 to 49 years, 11.38 in children younger than five, 10.82 in adults aged 50 to 69 years, 3.45 in children five to 14 years, and 3.12 in adults aged 70 years and older. Across all ages, the death rate was estimated to be 12.49 per 100,000 individuals.

While HIV-related deaths remain a problem, access to antiretrovirals significantly reduced the number of people dying from the disease. As of 2016, the estimated death from HIV/AIDS totaled to 1.01 million. Antiretroviral drug therapy (ART) averted approximately 1.21 million deaths. If antiretrovirals were not available, the possible total deaths would 2.22 million in 2016 alone.



Despite the access, many countries still lack coverage. Millions of people in certain regions do not benefit from the life-saving benefits of ARTs. These individuals likely have no access to HIV testing centers, which are required to expand the coverage of ARTs. Without testing centers, HIV transmission can go unnoticed and hamper the global effort against the disease.

Right now, people can only access two types of medications that combat HIV/AIDS. These are ARTs and prophylaxis. ARTs are prescribed to people clinically diagnosed with HIV. The drugs substantially slow down the disease to avoid AIDS. Prophylaxis, on the other hand, are medications designed to prevent HIV infection. This prevention method is divided into two variations.

Pre-exposure prophylaxis or PrEP is meant to protect a person at risk of HIV infection. It only works in people who have not contracted the disease. If they maintain PrEP, their odds to contract HIV is extremely low. If combined with other prevention measures, it will be nearly impossible for the person to catch the virus.

Post-exposure prophylaxis or PEP is intended to avoid HIV infection after potential exposure. Unlike PrEPs, PEPs only works within a limited window- about 72 hours after the exposure event. If taken sooner, the drugs have a higher chance of preventing HIV from establishing in the body. But like PrEPs, PEPs have a small chance of failure.



New Injectable Drug for HIV Treatment and Prevention

At the University of Utah, scientists developed an injectable drug that could prevent or treat HIV infection. It featured a component that restricted the virus from hijacking healthy cells. The drug could provide this protective effect for a long time with fewer side effects, compared to most HIV drugs. But the drug's efficacy was only confirmed in non-human primates. Further studies would be needed to optimize it for people.

"This is an exciting new HIV therapeutic option for both prevention and treatment, with a unique mechanism of action compared to other approved drugs. It has great potential to help patients who suffer from drug resistance as well as those who would benefit from a longer-acting, injectable anti-HIV drug cocktail," explained Dr. Michael S. Kay, a senior author of the study and professor of biochemistry at the University of Utah Health.

Some HIV patients are taking multiple antiretrovirals to keep the infection at bay. Although the drugs improved their quality of life, they can be prone to serious side effects. Moreover, ARTs tend to be expensive and if they stop, the virus may become resistant. So, they have no choice but to take antiretrovirals daily to avoid complications.

In this study, scientists tested a peptide against HIV. A total of 11 male and female rhesus monkeys were assigned as study samples. The peptide, CPT31, was administered and observed for inhibitory properties against the virus in vivo. Then, the animals were exposed to SHIV – the hybrid form of HIV and its simian virus counterpart.

Observations showed that CPT31 can block the ability of the virus to infect cells. The peptide specifically targets a part of HIV's fusion mechanism, which rarely mutates. As D-peptides, CPT31 does not degrade inside the body. This makes it last longer than natural peptides. It is also ignored by the immune system. This can remove side effects associated with unwanted immune response.

Monkeys were completely protected from SHIV exposure and never developed signs of infection. The observations also showed scientists the optimal dose of CPT31. For chronic SHIV infection, the drug was administered to untreated monkeys with SHIV. After 30 days, scientists checked the animals' viral loads and found them substantially lower.

Unfortunately, the virus rebounded between two and three weeks due to drug resistance. The resistance occurred since the monkeys were only treated with a single drug. But if the peptide was administered with another medication, drug resistance might not have happened.

The team is working with the company Navigen, which helped developed the peptide. The injectable drug is being improved for clinical trials. The first objective is to create an anti-HIV drug that can protect a person for three months with a single dose.