A clinical study involving the combination of two HIV vaccines and another drug to treat cancer found impeccable results for a possible one-time HIV treatment.

A combination of two HIV vaccines and another drug originally developed to treat cancer, Romidepsin, proved successful as an HIV treatment in recent trials, leaving five HIV-positive participants undetectable for up to seven months, reports Medical Daily.

According to a study presented at the Conference on Retroviruses and Opportunistic Infections, researchers put 24 newly diagnosed participants two HIV vaccines (they were still asked to be on antiretroviral therapy) for three years. Once those three years were over, 15 of them received an additional dose of one of the vaccines plus Romidepsin, then were subsequently taken off ART.

After serious monitoring, it was discovered the virus soon began to spread again in 10 of these patients, who were then quickly put back on ART.

But what surprised them all is that the remaining five remained undetectable with no need to take long-term daily drugs — and it is still unclear as to why.

“The idea of a therapeutic vaccine that could provide ongoing control of the virus without having to take a pill every day would be a huge advance,” executive director of the AIDS Vaccine Advocacy Coalition, Mitchell Warren, said to The Independent.

The five HIV-positive patients continue to be virally suppressed, even as long as seven months. While it’s too soon to ponder whether this strategy might be an effective one when searching for one-time HIV treatment, it’s still an interesting discovery that could open the door to more breakthroughs.