People at high risk of HIV infection have limited options when it comes to prevention of HIV. Currently, there is only one approved biomedical product: oral HIV pre-exposure prophylaxis, or PrEP, an antiretroviral pill on the market since 2012 that needs to be taken daily to prevent the transmission of HIV. Feedback from end users suggests that they would like more options when it comes to HIV prevention, and many would prefer long-acting dosage forms, such as injections or implants.
Another important issue for those at risk for HIV infection is discretion. Being in possession of condoms or antiretroviral pills, or making repeated visits to a local health clinic, can lead to unwanted scrutiny from friends, relatives, and neighbors.
Under the Thin-film Polymer Device Injectable for Prevention Program, supported by the U.S. President’s Emergency Plan for AIDS Relief through the U.S. Agency for International Development (USAID), our multidisciplinary team has been working on a potentially game-changing option to stem the HIV pandemic: a long-acting, biodegradable implant for HIV prevention in women. When implanted subcutaneously, our device releases a steady dose of antiretroviral drugs into the bloodstream for continuous protection from HIV. The device naturally and safely biodegrades after the drug has been released rather than having to be surgically removed.
Implantable Antiretrovirals: A Long Road from Conception to Implementation
Like any new medical product, developing a safe, effective, biodegradable implant for drug delivery involves years of research and testing. The idea of an antiretroviral biodegradable HIV implant had its genesis in 2013, when researchers recognized the need for additional options for HIV prevention beyond daily pills or coitally dependent condoms. Our team at RTI, along with key collaborators from the University of California, San Francisco and the Magee-Womens Research Institute and Foundation at the University of Pittsburgh, embarked on a two-year search for the right antiretroviral drug. This drug had to be compatible with the proposed implant delivery system and strong enough to be effective in small doses, so that the implant could be delivered with existing applicator systems like those used for contraceptive implants.
2017 marked a major milestone in the implantable antiretroviral project. In in vivo preclinical studies, we achieved a drug-delivery duration of three months from a single implant at doses believed to be sufficient to prevent HIV infection. Thanks to continued funding through USAID and an additional award from the Bill & Melinda Gates Foundation, we are now looking to extend implant effectiveness duration to six or even 12 months.
As this promising product continues to be developed, we hope to test our implant in humans within the next three years, with the aim of having a novel, long-acting antiretroviral delivery system on the market in 10 years. Understanding that the process from drug and device development to market often takes decades, this new implant has the long-term potential to be a game changer in the field of HIV prevention worldwide.
Expanding Implant Technology to Address Global Health Security Concerns
Another promising attribute of the antiretroviral implant is its versatility. In 2017, we obtained new funding from USAID to develop an implant for women that protects users from both HIV and unplanned pregnancy. In the longer term, the implant delivery systems being developed for HIV prevention and HIV and unplanned pregnancy prevention may ultimately be adapted for the treatment of other global medical issues, such as diabetes, tuberculosis, and even opioid addiction.
