Freya Biosciences reported Phase I data for FB301, a defined multi-strain Lactobacillus live biotherapeutic. The vaginally administered product candidate converted dysbiotic participants to a Lactobacillus-dominant microbiome profile at six months — positioning the Copenhagen- and Boston-based company to advance into Phase II studies targeting IVF-related embryo implantation failure and bacterial vaginosis.
Trial specifics
The first-in-human study was a randomized, double-blind, placebo-controlled, single-center trial enrolling 129 healthy female participants aged 18–45, of whom 89 were randomized across three dosing cohorts at a site in Germany.
Among participants who were dysbiotic at baseline — the modified intention-to-treat population — 50% (11/22) in the highest-dose cohort, which received once-daily vaginal capsules for ten days, had converted to a non-dysbiotic microbiome profile at six-month follow-up, compared with 11% (1/9) in the placebo group. Across all treatment arms, Lactobacillus abundance increased significantly from baseline (p < 0.001). The company also reported durable engraftment of FB301 product strains, a finding it described as validating the underlying discovery platform.
No serious adverse events, severe adverse events, or discontinuations were reported across any dosing cohort.
Development rationale
The biology underpinning FB301's development rests on an established but therapeutically underexplored connection between vaginal microbial composition and reproductive outcomes. A Lactobacillus-depleted vaginal environment has been associated with local immune activation and elevated inflammatory cytokines, which in turn may impair endometrial receptivity during embryo transfer. Current standard-of-care in IVF cycles addresses the hormonal dimension of implantation — vaginal progesterone products such as Endometrin and Crinone provide luteal phase support — but no approved therapy targets the dysbiotic microbiome as a contributing factor. FB301 is designed to correct that microbial state directly, without antibiotic pretreatment, which Freya's chief scientific officer Johan van Hylckama Vlieg cited as a specific differentiator in the announcement.