New Study Details How LACTIN-V Prevents Recurrent BV and Factors Influencing Its Effectiveness

A new study from the Kwon Lab at the Ragon Institute, published in Cell Host & Microbe, provides detailed insights into how a bacterial therapy, LACTIN-V, prevents recurrent bacterial vaginosis (BV) and identifies factors influencing its effectiveness.

Understanding Bacterial Vaginosis (BV)

BV is the most common vaginal condition globally, affecting over 25% of reproductive-age women. It is linked to health issues such as discharge, pain, preterm birth, cervical cancer, and increased risk of sexually transmitted infections like HIV.

Standard antibiotic treatments frequently result in recurrence, with over half of women experiencing BV again within a year.

This high recurrence rate is often due to the vaginal microbiome failing to establish a dominance of beneficial Lactobacillus crispatus after antibiotic treatment.

LACTIN-V: A Live Biotherapeutic Approach

LACTIN-V is a live biotherapeutic product containing L. crispatus. A previous randomized, placebo-controlled trial demonstrated that LACTIN-V significantly reduced BV recurrence when administered after metronidazole treatment. However, recurrence still occurred in 30% of women who received LACTIN-V, highlighting the need for a deeper understanding of its varying efficacy.

Deeper Insights from the Kwon Lab Study

To understand LACTIN-V's impact and the reasons for varying responses, the Kwon Lab analyzed over 1,100 samples from 213 trial participants. This comprehensive analysis involved microbiome sequencing, L. crispatus strain analysis, immune profiling, and clinical data.

Key Findings on LACTIN-V's Impact

• After 12 weeks of treatment, 30% of women receiving LACTIN-V developed a healthy, L. crispatus-dominant vaginal microbiome, compared to only 9% in the placebo group. This colonization pattern largely explained the treatment's benefits.
• L. crispatus colonization was primarily driven by the strain present in LACTIN-V, though in some instances, women's naturally occurring L. crispatus strains became dominant.

Predicting Treatment Response

The study identified several crucial factors that predict a woman's response to LACTIN-V therapy:

• A woman's vaginal microbiome composition before treatment was a key predictor of her response. Women whose microbiomes were predominated by Prevotella or Gardnerella species showed the most significant benefit from LACTIN-V.

Conversely, women predominated by Candidatus Lachnocurva vaginae (BVAB1), a bacterium strongly associated with BV, experienced minimal to no improvement.

• Other factors linked to successful L. crispatus colonization included lower bacterial levels and vaginal pH following metronidazole treatment, and specific pre-treatment immune profiles.

Expert Perspectives

Seth Bloom, co-first author of the paper, stated that the results offer key insights for vaginal health and and provide a roadmap for developing and utilizing LACTIN-V and similar live biotherapeutic products.

Doug Kwon, the study’s senior author, noted that the study offers the most detailed view to date on how a live biotherapeutic can reshape the vaginal microbiome to promote long-term vaginal health, enabling the design of more precise and effective treatments.