More than 36 million people worldwide are living with HIV, according to the World Health Organization (WHO
). Therefore, inexpensive, effective, and long-lasting medications are essential if the scientific community wants to successfully treat them.
Problems with adherence that plagued many individuals could be alleviated with the addition of new longer-acting HIV medications. These long-acting medications may also reduce costly laboratory tests to monitor their efficacy, and bring down drug costs—a major factor in middle- and low-income countries where HIV is most prevalent.
“With several highly potent agents in the pipeline and a healthy proliferation of many promising technologies for long-acting delivery, the prospects for very long-acting ARVs [anti-retrovirals] for treatment and prevention have never been brighter,” said Matthew Barnhart MD, MPH, medical officer for the US Agency for International Development (USAID) and associate editor of Global Health: Science and Practice
in a recent editorial
Dr. Barnhart outlined and described 5 types of drug developments that put HIV treatment on the threshold of a breakthrough:
1- or 2-Month Injectables
A combination of two antiretrovirals (AVRs), ViiV's cabotegravir (an integrase inhibitor) and Janssen's rilpivirine (a non-nucleoside reverse transcriptase inhibitor) is in phase 3 trials. The combination
is a monthly or every-other-month maintenance medication for people who have achieved non-detectable viral loads on standard ARV oral protocols. Investigators are also looking at cabotegravir alone as an every-other-month injection for HIV prevention
These include the capsid inhibitor GS-CA1, a new class of AVRs, and new nucleoside/tide reverse transcriptase inhibitors (NRTIs). Two of these NRTIs, EFdA (GS-9131) and TAF (tenofovir alafenamide fumarate), have the advantage of long half-lives that allow them to become “effectively trapped within cells, thereby amplifying their levels and potency,” Dr. Barnhart explained in his editorial. TAF, already approved as an oral medication, is being investigated as a drug that can be released from a long-lasting implant. Gilead’s GS-CA1 is in the pre-clinical stage, Merck’s EFdA is in phase 1, and Gilead’s TAF as an implant is in phase 1.