Vaginal Probiotic Capsule Shows Safety in IVF Implantation Failure: Study

An investigational vaginal probiotic capsule for IVF-related embryo implantation failure was found to be safe and well tolerated in early human trials and is set to advance to a phase II study.

The Phase 1 trial was a randomized, placebo-controlled, double-blind, single-center, first-in-human trial investigating safety, tolerability, and proof-of-concept following single and multiple dosing with FB301 in healthy female subjects aged 18-45. A total of 129 participants were enrolled, of whom 89 were randomized across three dosing cohorts at a single study site in Germany. Participants received either a single vaginal capsule of FB301 (Cohort 1), once-daily dosing for five days (Cohort 2), or once-daily dosing for ten days (Cohort 3).

The study met all primary and secondary endpoints, demonstrating that FB301 was safe and well tolerated across all cohorts, with no serious adverse events (SAEs), severe adverse events, or discontinuations reported.

Colleen Acosta, Chief Executive Officer of Freya Biosciences, commented: “FB301 showed a favorable safety profile across all dose levels and demonstrated clinically meaningful microbiome changes, including increases in key Lactobacillus species in the vaginal environment that are associated with superior health outcomes. Taken together, the data support the proposed mechanism of action of resolving a dysbiotic vaginal microbiome and addressing underlying inflammation, providing a strong foundation for clinical development in women undergoing assisted reproductive technologies. As we advance into Phase 2, our focus will be on confirming these findings in patient populations and progressing the development of a much-needed new therapeutic option that could help improve outcomes for the millions of women undergoing IVF worldwide.”

Treatment with FB301 resulted in a significant increase from baseline in the relative abundance of selected Lactobacillusspecies in vaginal samples, indicating modulation of the vaginal microbiome toward a more advantageous state. In participants who were dysbiotic at baseline (the modified intention-to-treat population), treatment with FB301 led to conversion to a Lactobacillus-dominant microbiome profile across all dosing cohorts. At the 6-month follow-up, 50.0% (11/22) of participants in the highest dose group (Cohort 3) had converted to a non-dysbiotic profile, compared with 11.1% (1/9) in the placebo group. Statistical analyses confirmed significant increases in Lactobacillus abundance versus baseline across treatment arms (p < 0.001), with additional pooled analyses supporting treatment effects compared to placebo.

Johan van Hylckama Vlieg, Chief Scientific Officer of Freya Biosciences, added: “We are encouraged that FB301 met the secondary endpoint of improving Lactobacillus abundance compared to placebo, without the need for antibiotic pretreatment. The study further demonstrated durable engraftment of FB301 product strains, validating our Dyscover™ platform for the discovery of therapeutic candidates that correct local immune dysregulation – a mechanism critical to reproductive health.”

Freya is advancing FB301 into Phase 2 clinical development to evaluate its potential in women undergoing assisted reproductive technologies including frozen embryo transfer, as well as in a bacterial vaginosis (BV) population to further optimize the treatment regimen. An Investigational New Drug (IND) application has been cleared by the FDA for a US study in women undergoing frozen embryo transfer, and a Clinical Trial Application (CTA) has been approved in Germany for a BV treatment optimization study .