ST Pharm announced on 14th July the top-line results of a Phase 2a clinical trial conducted in the United States for STP0404, its candidate treatment for HIV-1 infection.
STP0404 works through an allosteric integrase inhibitor (ALLINI) mechanism — a novel mode of action distinct from existing HIV therapies. Crucially, this trial marks the first time antiviral efficacy for an ALLINI-class compound has been demonstrated at the proof-of-concept (PoC) stage in a clinical setting.
In the trial, 36 HIV-1-infected patients received a once-daily oral dose of STP0404 over ten days. Plasma HIV-1 RNA levels fell across all dosage groups, and the results achieved statistical significance compared with the placebo group.
At the highest dose of 600mg, the HIV-1 viral load declined by approximately 97.5%. The safety profile was broadly reassuring: most adverse events were mild, and there were zero instances of Grade 3 or higher severe adverse events, serious adverse events (SAEs), treatment discontinuations, or deaths.
Detailed data from the trial are expected to be presented at IDWeek, the annual infectious diseases conference, in October 2026.
The global HIV therapeutics market is valued at approximately $32.8 billion. Standard practice in HIV treatment involves combining drugs with different mechanisms of action to prevent the emergence of drug resistance.
Because STP0404 operates through a mechanism not shared by existing treatments, it could serve as a new combination therapy option. However, progressing to combination treatment trials would require collaboration with a major global pharmaceutical company.
IBK Investment Securities said in a research note that the confirmed antiviral efficacy and safety of this novel mechanism had meaningfully raised the likelihood of ST Pharm securing a partnership or technology licensing agreement.