Emerging experimental therapies
In this issue of TreatmentUpdate, we summarize results of recent clinical trials that sought to explore the effects of combinations of drugs. Many of these drugs are experimental and the clinical trials were of relatively short duration. It will likely be several years before one or more of them are approved as they make their way through clinical trials.
Some of these drugs are new compounds, while others are super antibodies (technically called broadly neutralizing antibodies, or bNAb). These antibodies bind to HIV, and in laboratory studies with cells or animals they are usually highly effective at stopping HIV from infecting cells. Preliminary studies in people have found that some antibodies are highly effective. Not every person with HIV has virus that is highly susceptible to these antibodies.
In addition, pharmaceutical companies are investigating long-lasting formulations of HIV treatments. For instance, the drug cabotegravir is used together with another drug called rilpivirine—both drugs injected every one or two months (depending on what the doctor and patient decide) for HIV treatment. The combination is sold as Cabenuva in North America. The developer of these drugs, ViiV Healthcare, is investigating a longer-acting formulation that can be given every four months.
Another company Gilead Sciences has developed a drug called lenacapavir (Sunlenca) that can be given every six months by subcutaneous injection (just under the skin). However, lenacapavir needs to be paired with another drug that is also long-lasting. A search for such a partner drug is underway. Gilead also has a new integrase inhibitor under development.
Researchers who are independent of these two companies have called for a treatment regimen that combines two long-acting formulations—cabotegravir and lenacapavir—even though both drugs have different dosing schedules. A large clinical trial will be needed to find out if the use of two drugs with different dosing schedules (every two vs. every six months) is practical for patients.
Note that we currently have limited details about experimental combinations of drugs and antibodies.
Much research is needed to find out more about the long-term effectiveness of super antibodies and for whom they will be most suitable.
—Sean R. Hosein