MOUNTAIN VIEW, Calif., ARLINGTON, Va., and LONDON, England, May 13, 2026
Osel Inc., in partnership with March of Dimes and the Imperial Clinical Trials Unit, announced the launch of the FLIP-2 Phase 2b clinical trial evaluating LACTIN-V, a microbiome-based live biotherapeutic product designed to reduce the risk of preterm birth (PTB) in high-risk pregnant women. The study represents one of the most advanced clinical evaluations of a microbiome-targeted therapy in maternal health and could mark a major breakthrough in preventing premature labor.
LACTIN-V Targets Vaginal Microbiome Imbalance
LACTIN-V is a live biotherapeutic product (LBP) containing the beneficial bacterium Lactobacillus crispatus, delivered vaginally using a proprietary applicator. The therapy is designed to restore and maintain a healthy vaginal microbiome, reducing inflammation and stabilizing protective bacterial populations linked to healthy pregnancies.
Researchers believe that disruption of the vaginal microbiome is a major but underrecognized contributor to preterm birth, premature rupture of membranes (PPROM), late miscarriage, and low-birthweight infants. Women with low levels of Lactobacillus crispatus and higher microbial diversity are considered to have significantly greater risk of inflammatory complications associated with early labor.
The double-blind, placebo-controlled FLIP-2 study plans to enroll 360 pregnant women identified as high risk for preterm birth across four maternity centers in the United Kingdom. The trial is being led by Dr. Lynne Sykes, Professor Phillip Bennett, and Dr. Ryan Love at the March of Dimes Prematurity Research Center.
According to investigators, the study aims to evaluate whether restoring a healthier vaginal microbiome can prevent the biological triggers that initiate premature labor, representing a fundamentally different strategy from existing interventions.
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Trial Builds on Encouraging FLIP-1 Results
The Phase 2b program follows promising findings from the earlier FLIP-1 Phase 1 study, which demonstrated that LACTIN-V was safe, well tolerated, and highly acceptable among pregnant women at elevated risk of preterm birth. Researchers also observed lower preterm birth rates compared with historical controls, providing the rationale for advancing into a larger randomized controlled trial.
Professor Phillip Bennett, Acting Head of the Department of Metabolism, Digestion and Reproduction at Imperial College London, described the study as a major shift in the prevention of preterm birth. Unlike previous therapies aimed at stopping labor after it begins, the microbiome-based approach seeks to prevent activation of inflammatory pathways that trigger early delivery.
Dr. Lynne Sykes stated that the trial offers an opportunity to move toward more personalized and precision-based obstetric care, targeting a clearly defined biological cause of preterm birth rather than relying on generalized treatment approaches.
The trial is funded through support from March of Dimes and the NIHR Imperial Biomedical Research Centre, highlighting growing international investment in microbiome-focused maternal health research.
Preterm Birth Remains a Major Global Health Crisis
Preterm birth remains the leading cause of death among children under five worldwide, accounting for nearly one million deaths annually. Survivors often experience lifelong complications including neurological disorders, developmental delays, and chronic health conditions.
The medical need has become even more urgent following the 2023 withdrawal of FDA approval for Makena® (hydroxyprogesterone caproate) after post-market studies failed to confirm its effectiveness in preventing preterm birth. Currently, there are no FDA-approved therapies specifically indicated for PTB prevention.
Osel Inc. believes LACTIN-V could become a pioneering microbiome-based therapeutic option in women’s health if the FLIP-2 study demonstrates clinical success. The company holds an exclusive worldwide license for the intellectual property covering the use of LACTIN-V in preterm birth prevention.
Source: Osel Inc press release
