Pooled allogeneic faecal microbiota MaaT013 for steroid-resistant gastrointestinal acute graft-versus-host disease: a single-arm, multicentre phase 2 trial.

Background: Failure of gastrointestinal acute graft-versus-host disease (GI-aGvHD) to respond to steroid therapy is associated with limited further therapeutic options. We aimed to assess the safety and efficacy of the first-in-human use of the pooled allogeneic faecal microbiota, MaaT013, for the treatment of steroid-refractory GI-aGvHD. Methods: This prospective, international, single-arm, phase 2a study reports clinical outcomes from a 24-patient cohort with grade III-IV, steroid refractory GI-aGvHD treated with the pooled allogeneic faecal microbiota MaaT013. MaaT013 involved pooling faecal matter from 3 to 8 screened donors then transplanting the pooled batches into patients to treat GI-aGVHD. The 24 patients were treated in the HERACLES study (Aug 2018 to Nov 2020) at 26 sites in Europe and an additional 52 patients were treated in a compassionate use/expanded access program (EAP) in France (July 2018 to April 2021). The primary endpoint was GI response at day 28, defined as the proportion of patients with GI-aGvHD who had a complete response (CR) or very good partial response (VGPR). GvHD grading and staging were assessed according to the revised Glucksberg criteria. Adverse events and severe adverse events were monitored for 6 months and 12 months, respectively. The HERACLES study was registered with ClinicalTrials.gov (NCT03359980). Findings: Compared with single donors, MaaT013 is characterised by higher microbial richness and reduced variability across batches. At day 28 (D28), the GI-overall response rate (ORR) was 38% in the prospective population, including 5 complete responses (CR), 2 very good partial responses (VGPR) and 2 partial responses (PR). In the EAP, the GI-ORR was 58% (17 CR, 9 VGPR and 4 PR). The 12-month overall survival (OS) was 25% in the prospective study and 38% in the EAP. Regarding safety, five infectious complications, including 3 sepsis, could not be excluded from being related to the study procedure in HERACLES. Shotgun sequencing analyses of the identified strains suggest that none were found in MaaT013. In the EAP, 18 pharmacovigilance cases were reported among 52 treated patients, including 11 bacteraemia/sepsis. In HERACLES, we observed in stools from responding patients at D28 a higher microbiota richness and increased levels of beneficial bacteria, in particular butyrate producers, along with increased levels of short-chain fatty acid and bile acids. In contrast, stools from non-responding (NR) patients displayed increased levels of pathogenic pro-inflammatory bacteria along with increased systemic inflammatory parameters. Interpretation: Overall, MaaT013 was safe in this population of highly immunocompromised patients and was associated with responses in some patients with GI-aGvHD and deserves further investigation. Funding: MaaT Pharma.

Gut microbiota diversity after autologous fecal microbiota transfer in acute myeloid leukemia patients.

Acute myeloid leukemia (AML) intensive chemotherapy combined with broad-spectrum antibiotics, leads to gut microbiota dysbiosis promoting pathological conditions and an increased incidence of complications. Here we report findings from a phase II single-arm, multicenter study evaluating autologous fecal microbiota transfer (AFMT) in 25 AML patients treated with intensive chemotherapy and antibiotics (ClinicalTrials.gov number: NCT02928523). The co-primary outcomes of the study are to evaluate the efficacy of AFMT in dysbiosis correction and multidrug-resistant bacteria eradication. The main secondary outcomes are to define a dysbiosis biosignature, to evaluate the effect of dysbiosis correction on patient clinical status, to assess the short and mid-term safety of AFMT in this immunocompromised population, and to evaluate the feasibility of the AFMT procedure and acceptability by the patient. Intensive induction chemotherapy induces a dramatic decrease of α-diversity indices, and a microbial dysbiosis with a significant shift of the microbial communities and domination of pro-inflammatory families. After AFMT treatment, α-diversity indices return to their initial mean levels and the similarity index shows the restoration of microbial communities. The trial meets pre-specified endpoints. AFMT appears to be safe and may be effective for gut microbiota restoration in AML patients receiving intensive chemotherapy and antibiotics, with an excellent gut microbiota reconstruction based on both richness and diversity indices at the species level.

MAVS deficiency induces gut dysbiotic microbiota conferring a proallergic phenotype.

Prominent changes in the gut microbiota (referred to as "dysbiosis") play a key role in the development of allergic disorders, but the underlying mechanisms remain unknown. Study of the delayed-type hypersensitivity (DTH) response in mice contributed to our knowledge of the pathophysiology of human allergic contact dermatitis. Here we report a negative regulatory role of the RIG-I-like receptor adaptor mitochondrial antiviral signaling (MAVS) on DTH by modulating gut bacterial ecology. Cohousing and fecal transplantation experiments revealed that the dysbiotic microbiota of Mavs-/- mice conferred a proallergic phenotype that is communicable to wild-type mice. DTH sensitization coincided with increased intestinal permeability and bacterial translocation within lymphoid organs that enhanced DTH severity. Collectively, we unveiled an unexpected impact of RIG-I-like signaling on the gut microbiota with consequences on allergic skin disease outcome. Primarily, these data indicate that manipulating the gut microbiota may help in the development of therapeutic strategies for the treatment of human allergic skin pathologies.

Overexpression of the transcription factor Sp1 activates the OAS-RNAse L-RIG-I pathway.

Deregulated expression of oncogenes or transcription factors such as specificity protein 1 (Sp1) is observed in many human cancers and plays a role in tumor maintenance. Paradoxically in untransformed cells, Sp1 overexpression induces late apoptosis but the early intrinsic response is poorly characterized. In the present work, we studied increased Sp1 level consequences in untransformed cells and showed that it turns on an early innate immune transcriptome. Sp1 overexpression does not activate known cellular stress pathways such as DNA damage response or endoplasmic reticulum stress, but induces the activation of the OAS-RNase L pathway and the generation of small self-RNAs, leading to the upregulation of genes of the antiviral RIG-I pathway at the transcriptional and translational levels. Finally, Sp1-induced intrinsic innate immune response leads to the production of the chemokine CXCL4 and to the recruitment of inflammatory cells in vitro and in vivo. Altogether our results showed that increased Sp1 level in untransformed cells constitutes a novel danger signal sensed by the OAS-RNase L axis leading to the activation of the RIG-I pathway. These results suggested that the OAS-RNase L-RIG-I pathway may be activated in sterile condition in absence of pathogen.

[Human retrovirus XMRV: The end of an exciting story?] / Rétrovirus humain XMRV : la fin d'une histoire séduisante ?

Viruses represent an important cause of cancer in humans: infections are estimated to account for close to one cancer case out of five.With the ongoing discovery of new infectious agents, this number should be raising in the near future. In 2006, the discovery of a new _-retrovirus in prostate cancer biopsies launched an intense research activity: could this new xenotropic MLV-related virus (XMRV) be the cause of prostate cancer? Five years later, the initial enthusiasm of retrovirologists has dramatically diminished. One by one, arguments favouring the hypothesis of human infection with XMRV are being refuted. The aim of this review article is to present the discovery of XMRV and to analyze recent data arguing against its existence in humans. A synthetic interpretation of XMRV literature will then be suggested.