A preprint published today in medRxiv reports results from the VIBRANT Phase 1 trial, a first-in-human study of two novel, multi-strain Lactobacillus crispatus live biotherapeutic products (LBPs) designed to reduce recurrence of bacterial vaginosis (BV). The paper is available here. The study was a major collaborative effort funded by the Bill & Melinda Gates Foundation through the Vaginal Microbiome Research Consortium (VMRC), a multi-institutional initiative aimed at developing new interventions to improve women’s vaginal health. The clinical trial was co-led by Dr. Caroline Mitchell at Massachusetts General Hospital and Dr. DiseboPotloane at CAPRISA in Durban, South Africa, with contributions from numerous collaborators across the United States, Belgium, and South Africa.
BV affects nearly 30% of women worldwide and is linked to serious health risks such as increased susceptibility to sexually transmitted infections, including HIV and HPV, cervical dysplasia, miscarriage, and preterm birth. Standard antibiotic treatments often fail long-term, with recurrence rates as high as 60% within six months due to poor recolonization by protective Lactobacillus species.
The VIBRANT trial, conducted in South Africa and the United States, enrolled women with BV who first received metronidazole and were then randomized to one of two multi-strain Lactobacillus crispatus vaginal tablets (LC106 or LC115) or placebo. Both products were designed by investigators at the Center for Advanced Microbiome Research and Innovation (CAMRI), Institute for Genome Sciences, University of Maryland School of Medicine, drawing on their expertise in vaginal microbial ecology. CAMRI scientists, including Dr. Michael France and Dr. Jacques Ravel, played a central role in designing these LBPs and contributed to trial analyses. Importantly, the metagenomic data from the study were analyzed using kSanity, an innovative k-mer–based tool for precision bacterial strain detection and quantification developed by Dr. Michael France at CAMRI, recently published as a preprint in bioRxiv.
Key Findings from the VIBRANT trial:
• Colonization success: 66% of women in the active arms achieved colonization with L. crispatus strains in the first five weeks.
• Durability: Nearly half of those colonized (49%) remained colonized at 12 weeks despite only 3–7 days of dosing.
• Reduced recurrence: Women who achieved colonization had lower recurrence of BV over 12 weeks compared to those who did not.
• Safety: Both products were safe, well tolerated, and acceptable, with no serious adverse events reported.
Metagenomic sequencing was conducted at Maryland Genomics, Institute for Genome Sciences. The full study protocol was published earlier this week in Contemporary Clinical Trials Communications, providing transparency on study design and methodology.
“These findings highlight the feasibility of multi-strain L. crispatus LBPs to achieve durable colonization across geographically diverse populations,” said Dr. Jacques Ravel, CAMRI Director. “We are encouraged by the results and view them as an important step toward improving women’s health through microbiome-based interventions.”
While larger trials will be needed to assess efficacy, the VIBRANT trial establishes proof-of-concept that carefully designed, multi-strain vaginal LBPs can safely engraft and potentially reduce recurrence of BV.