Efficacy and safety of topically applied therapeutic ammonia oxidising bacteria in adults with mild-to-moderate atopic dermatitis and moderate-to-severe pruritus: a randomised, double-blind, placebo-controlled, dose-ranging, phase 2b trial

Background

Topical anti-inflammatory therapy is a cornerstone of treatment for atopic dermatitis (AD). However, many unmet needs remain with existing therapies. B244 is a live topical biotherapeutic being tested for the reduction of pruritus and improvement of eczema signs in patients with AD. We aimed to assess the safety and efficacy of B244, compared to vehicle, for patients with mild-to-moderate AD and moderate-to-severe pruritus.

Methods

In this randomised, placebo-controlled, double-blind phase 2b trial, adults aged 18-65 years with mild-to-moderate AD and moderate-to-severe pruritus were enrolled across 56 sites in the USA. Patients were randomised 1:1:1 into a low-dose (optical density at 600 nm [OD] 5.0), high-dose (OD 20.0), or vehicle group for the 4-week treatment period and a 4 week follow-up period. Patients were instructed to apply the topical spray twice daily throughout the treatment period. Randomisation was centrally based (random alternating blocks of 6 and 3) and stratified by site. All participants, investigators, and those assessing outcomes were blinded to the treatment group assignments. The primary endpoint was the mean change in pruritus as measured by the Worst Itch Numeric Rating Scale (WI-NRS) at 4 weeks. Safety was tracked throughout the study. Primary efficacy analyses included the modified intent-to-treat (mITT) population, encompassing those who received at least one dose of study drug and attended at least one post-baseline visit. The safety population included all participants who received at least one does of study drug. This study is registered with ClinicalTrials.gov, NCT04490109.

Findings

Between June 4, 2020 and October 22, 2021, 547 eligible patients were enrolled. All study endpoints were meaningfully improved with B244 compared to vehicle. The WI-NRS score was reduced by 34% (-2.8 B244 vs -2.1 placebo, p = 0.014 and p = 0.015 for OD 20.0 and OD 5.0), from a baseline score of >8. B244 was well tolerated with no serious adverse events (SAEs); treatment-emergent adverse events (TEAEs) and treatment related TEAEs were low in incidence, mild in severity, and transient. 33 (18%) of 180 patients given B244 OD 5.0, 29 (16%) of 180 patients given B244 OD 20.0, and 17 (9%) of 186 patients given placebo reported treatment-emergent adverse events; headache was the most frequent (3%, 2%, and 1%, respectively).

Interpretation

B244 was well tolerated and demonstrated improved efficacy compared to vehicle in all primary, secondary, and exploratory endpoints and should be further developed as a novel, natural, fast-acting topical spray treatment option for AD and associated pruritus.

Funding

AOBiome Therapeutics.

Functional proteomics reveals the biochemical niche of C. elegans DCR-1 in multiple small-RNA-mediated pathways

In plants, animals, and fungi, members of the Dicer family of RNase III-related enzymes process double-stranded RNA (dsRNA) to initiate small-RNA-mediated gene-silencing mechanisms. To learn how C. elegans Dicer, DCR-1, functions in multiple distinct silencing mechanisms, we used a mass-spectrometry-based proteomics approach to identify DCR-1-interacting proteins. We then generated and characterized deletion alleles for the corresponding genes. The interactors are required for production of three species of small RNA, including (1) small interfering RNAs (siRNAs), derived from exogenous dsRNA triggers (exo-siRNAs); (2) siRNAs derived from endogenous triggers (endo-siRNAs); and (3) developmental regulatory microRNAs (miRNAs). One interactor, the conserved RNA-phosphatase homolog PIR-1, is required for the processing of a putative amplified DCR-1 substrate. Interactors required for endo-siRNA production include ERI-1 and RRF-3, whose loss of function enhances RNAi. Our findings provide a first glimpse at the complex biochemical niche of Dicer and suggest that competition exists between DCR-1-mediated small-RNA pathways.

Wnt signaling drives WRM-1/beta-catenin asymmetries in early C. elegans embryos

beta-Catenin regulates cell adhesion and cellular differentiation during development, and misregulation of beta-catenin contributes to numerous forms of cancer in humans. Here we describe Caenorhabditis elegans conditional alleles of mom-2/Wnt, mom-4/Tak1, and wrm-1/beta-catenin. We use these reagents to examine the regulation of WRM-1/beta-catenin during a Wnt-signaling-induced asymmetric cell division. While WRM-1 protein initially accumulates in the nuclei of all cells, signaling promotes the retention of WRM-1 in nuclei of responding cells. We show that both PRY-1/Axin and the nuclear exportin homolog IMB-4/CRM-1 antagonize signaling. These findings reveal how Wnt signals direct the asymmetric localization of beta-catenin during polarized cell division.

A member of the polymerase beta nucleotidyltransferase superfamily is required for RNA interference in C. elegans

RNA interference (RNAi) is an ancient, highly conserved mechanism in which small RNA molecules (siRNAs) guide the sequence-specific silencing of gene expression . Several silencing machinery protein components have been identified, including helicases, RNase-related proteins, double- and single-stranded RNA binding proteins, and RNA-dependent RNA polymerase-related proteins . Work on these factors has led to the revelation that RNAi mechanisms intersect with cellular pathways required for development and fertility . Despite rapid progress in understanding key steps in the RNAi pathway, it is clear that many factors required for both RNAi and related developmental mechanisms have not yet been identified. Here, we report the characterization of the C. elegans gene rde-3. Genetic analysis of presumptive null alleles indicates that rde-3 is required for siRNA accumulation and for efficient RNAi in all tissues, and it is essential for fertility and viability at high temperatures. RDE-3 contains conserved domains found in the polymerase beta nucleotidyltransferase superfamily, which includes conventional poly(A) polymerases, 2'-5' oligoadenylate synthetase (OAS), and yeast Trf4p . These findings implicate a new enzymatic modality in RNAi and suggest possible models for the role of RDE-3 in the RNAi mechanism.