Science Active ingredient effectively protects against HIV infection
A six-monthly vaccination with the drug lenacapavir effectively protects against HIV infection. This is confirmed by data from the pivotal phase 3 study "Purpose 2", which is presented in the "New England Journal of Medicine" ("NEJM").
28.11.2024, 02:18
28.11.2024, 02:19
SDA
Astrid Berner-Rodoreda from Heidelberg University Hospital praised lenacapavir as a real breakthrough. As a depot injection, lenacapavir provides long-term protection against HIV infection, with a booster scheduled every six months - previously used drugs for HIV pre-exposure prophylaxis (PrEP) such as Truvada must be taken daily as a tablet. Getting vaccinated twice a year is much more convenient than having to remember to take a tablet every day, said Berner-Rodoreda.
Tablets make the environment suspicious
There is also a certain effect: especially in some countries that are heavily affected by HIV, there is a risk of being labeled as HIV-positive by those around you if you take tablets every day. An injection administered only twice a year is much easier to keep secret. There is therefore no question that lenacapavir is a "huge relief" for many people.
As with the previous study "Purpose 1", the evaluation was ended early due to the promising results in order to make the drug available to all test subjects, according to the manufacturer Gilead. Lenacapavir will now be submitted for approval as HIV protection in numerous countries. Targeted efforts are also being made to provide the drug in poorer countries.
Comparably efficient protection
The drug is to be offered prophylactically to people with a high risk of HIV infection. It inhibits the life cycle of the virus at several stages of the infection. In terms of efficiency, lenacapavir is comparable to Truvada, explained Max von Kleist from the Free University of Berlin. Both offer excellent, almost complete protection.
Although the results of the two "Purpose" studies appear to show that there are proportionately more infections in the control groups treated with tablets, the data is deceptive, explained the head of the "Mathematics for Data Science" research group. In many cases, the tablets were not taken regularly or were no longer taken at all towards the end of the study period. It is not surprising that infections then occur.
Lenacapavir is already approved in the EU for the antiviral treatment of certain patients who are already infected. Gilead has not yet launched the drug on the market in Germany. It is unclear whether it will be available in this country as a preventative treatment, said Berner-Rodoreda. However, it is particularly important for poorer countries, such as women in sub-Saharan Africa.
Will it be affordable for those who need it most?
There is a problem here: Lenacapavir costs around 42,000 dollars per year in the USA when used to treat an existing infection - at this level, it would be unaffordable for people in poorer countries. Berner-Rodoreda emphasized that it is crucial that access is made possible for those countries where the drug is really urgently needed.
For whom and under what circumstances lenacapavir should be chosen must be carefully considered, added von Kleist. This is because - as is generally the case with such active substances - there is a risk of resistance developing. The problem with lenacapavir in particular is that the active ingredient can still be detected in the body for around a year after vaccinations have been stopped. "This promotes the development of resistance." A pathogen can become resistant if the dose of an active substance is not sufficient to eliminate it, but puts it under selection pressure.
Discontinuation only with follow-up treatment?
According to von Kleist, it may be necessary to take Truvada for another year after discontinuing lenacapavir in order to prevent the development of resistance in the event of infection during this period. With Truvada, the corresponding risk is low: it disappears from the body within a week if it is no longer taken.
"Purpose 2" included almost 3300 HIV-negative people who had sex frequently. Two people in the lenacapavir group (approx. 2,200 test subjects) and nine in the group treated with Truvada for comparison (approx. 1,100 test subjects) became infected with HIV, according to the journal. Lenacapavir thus reduced the risk of infection by 96 percent compared to the background incidence. Both drugs were generally well tolerated.
Promising results from the Phase III "Purpose 1" study were presented at the World AIDS Conference in Munich in July and published in the NEJM. Around 5,300 HIV-negative girls and young women in South Africa and Uganda were involved in the study. There were no infections among the 2,100 or so participants who were injected with lenacapavir twice a year. In control groups with around 3200 participants who had taken other drugs for prevention, there were 55 HIV infections.
Cure still not possible
The HI virus weakens the immune system and makes the body susceptible to various diseases. The clinical picture is called AIDS. If detected and treated early, infected people have a practically normal life expectancy. However, the infection cannot be completely eliminated in most cases, which is why lifelong use of virus-inhibiting medication is necessary.
According to a UN report presented on Tuesday, the number of HIV infections is rising in 28 countries. Worldwide, 39.9 million people are living with the virus, most of them in sub-Saharan Africa, according to the UN program UNAIDS. In 2023, 630,000 people died in connection with AIDS and 1.3 million people were newly infected with the HI virus.
