NCT07453069

Effect of FB301 on Vaginal Bacterial Profile in Women With Asymptomatic Vaginal Dysbiosis Undergoing a Mock Frozen Embryo Transfer Cycle

A Randomized, Double-blind, Three Arm, Multi-center Phase 2 Study to Investigate the Molecular Efficacy and Safety of FB301/Chlorhexidine Compared With FB301/Sham and Placebo/Sham in a Mock FET Cycle in Female Participants 18-40 Years of Age With Asymptomatic Vaginal Molecular Dysbiosis Planning to Undergo a Frozen Embryo Transfer (FET) Cycle

• Status: Not Yet Recruiting
• Phase: Phase 2
• Study type: Interventional
• Enrollment: 30 (estimated)
• Sponsor: Freya Biosciences ApS · Industry
• Sex: Female
• Age: 18 Years – 40 Years
• Healthy volunteers: Not accepted

Summary

The goal of this clinical trial is to evaluate FB301 during a mock frozen embryo transfer (FET) cycle in pre-menopausal women aged 18 to 40 years with a prior failed FET and a defined vaginal bacterial imbalance (dysbiosis). The main question it aims to answer is: • Does treatment with FB301 during a mock FET cycle change the proportion of participants who meet the predefined vaginal bacterial threshold compared with placebo? Researchers will compare: * FB301 given after an initial vaginal cleansing with chlorhexidine (an antiseptic solution), * FB301 given after an initial vaginal cleansing with saline (saltwater), and * A placebo capsule given after an initial vaginal cleansing with saline to determine whether these approaches affect vaginal bacterial composition and pregnancy outcomes. Participants will take study treatment for 15 days during a "mock" FET cycle. In a mock cycle, participants receive the hormones needed to prepare the uterus for embryo transfer, but no embryo is transferred. After completing the mock cycle, participants will proceed with their planned frozen embryo transfer and will be followed during pregnancy until birth. Participants will: * Undergo a vaginal cleansing before receiving the first dose of FB301 or placebo * Provide vaginal swab samples at up to 5 study visits * Attend the study centre for up to 8 visits and participate in up to 4 follow-up phone calls * Complete a mock FET cycle before proceeding with their planned frozen embryo transfer cycle Participants who become pregnant will be followed until birth.

Detailed description

Vaginal dysbiosis characterized by reduced relative abundance of Lactobacillus species has been associated with reproductive outcomes in women undergoing frozen embryo transfer (FET). This study evaluates the safety, tolerability, and molecular effects of FB301 in women undergoing FET who have no known underlying clinical gynecological conditions but are identified as having molecular dysbiosis by metagenomic sequencing of a vaginal swab collected at screening. Participants will be randomized to one of three arms: (1) FB301 following a single initial vaginal cleansing with chlorhexidine (an antiseptic solution), (2) FB301 following a single sham cleansing with saline, or (3) placebo following sham cleansing. Cleansing occurs once prior to initiation of study treatment. Participants will then receive 15 days of study treatment during a mock frozen embryo transfer (FET) cycle in which participants receive hormonal preparation of the endometrium but no embryo is transferred. Following completion of the mock cycle, participants will proceed with their planned frozen embryo transfer during the subsequent menstrual cycle, in accordance with standard clinical practice. Participants who become pregnant will be followed until birth. The primary objective is to evaluate whether treatment increases the proportion of participants achieving a predefined Lactobacillus-dominant vaginal bacterial profile following therapy. Secondary objectives include evaluation of biochemical pregnancy (confirmed by serum beta-hCG testing) and clinical pregnancy (confirmed by transvaginal ultrasound) following the subsequent planned FET cycle.

Conditions

• Vaginal Dysbiosis

Interventions

Type	Name	Description
DRUG	FB-301	FB301 capsule
DRUG	Placebo	FB301 Placebo capsule
OTHER	Chlorhexidine (0.5%) Vaginal Cleanse	Vaginal cleanse with 0.5% Chlorhexidine solution prior to first IP administration
OTHER	Sham vaginal cleanse (saline)	Vaginal cleanse with saline solution prior to first IP administration.

Timeline

• Start date: 2026-04-15
• Primary completion: 2026-10-31
• Completion: 2027-09-30
• First posted: 2026-03-05
• Last updated: 2026-03-05

Locations

1 site across 1 country: United States

Regulatory

• FDA-regulated drug study