Abstracts

Rationale: The gastrointestinal microbiota comprises a complex community of bacteria, fungi, and archaea that significantly influence health by modulating metabolic and neurological pathways. BL-001 is an oral, live biotherapeutic product being developed for the treatment of multiple neurological diseases, including Dravet syndrome and other rare epilepsies. BL-001 was first designed to mimic the antiepileptic effect of the ketogenic diet and has potency in cell-based assays and animal studies to eliminate neuronal hyperexcitability, increase GABA in the hippocampus, and reduce or eliminate seizure frequency and duration. One of the challenges with traditional drug development is that the information learned at each stage is limited. To combat that and derisk the larger program we evaluated ways to gain early insights into efficacy despite only having dosed healthy volunteers. We report a Phase 0 trial in healthy volunteers of BL-001 to assess strain kinetics and tolerability, followed by fecal microbiota transplant from volunteer-to-mice for seizure protection testing.

Methods: Healthy volunteers (n=3) each took three increasing doses over a 12-day period of the two bacterial strains in the live biotherapeutic product BL-001. Stool samples were collected before, during, and after dosing, and DNA was extracted for metagenomic sequencing and bacterial strain kinetics measurements. Stool samples from the baseline and high dose periods were transferred to germ-free mice (n=14 per each sample) and tested in the stepwise 6-Hz seizure model (categorized as a partial or focal form of seizure). Fecal samples were collected from the mice during the course of the study.

Results: BL-001 strains were present in high levels in subjects during the high dosing period and displaced other closely related strains over time. Additionally, minimal impacts to the native microbiota were observed from microbiome richness and evenness metrics. Dosing was well-tolerated, although subject journals noted symptoms associated with ketogenic diet studies, including some brain fog and fatigue (adverse events were logged as mild and were resolved). Fecal microbiota transplant including BL-001 strains from the highest dose period stool samples conferred seizure protection in mice as observed by increased CC50, the critical current intensity needed to induce seizures in 50% of mice tested. Metagenomic sequencing showed these mice to have higher relative abundance of BL-001 strains post-transplant.

Conclusions: All doses of BL-001 strains administered to healthy volunteers were shown to be safe and well tolerated with positive strain kinetics observed and overall microbiome diversity preserved. More specifically, the BL-001 component strains showed significant changes while minimizing any off-target effects in the rest of the microbiome. Seizure testing in mice receiving fecal microbiota transplant of BL-001 from dosed human stool samples provided seizure protection and demonstrates therapeutic potential of BL-001.

Funding: This study was funded by Bloom Science.