What is the value of a food and drug administration investigational new drug application for fecal microbiota transplantation to treat Clostridium difficile Infection?

Safety and Tolerability of SER-109 as an Investigational Microbiome Therapeutic in Adults With Recurrent Clostridioides difficile Infection: A Phase 3, Open-Label, Single-Arm Trial

IMPORTANCE

A safe and effective treatment for recurrent Clostridioides difficile infection (CDI) is urgently needed. Antibiotics kill toxin-producing bacteria but do not repair the disrupted microbiome, which promotes spore germination and infection recurrence.

OBJECTIVES

To evaluate the safety and rate of CDI recurrence after administration of investigational microbiome therapeutic SER-109 through 24 weeks.

DESIGN, SETTING, AND PARTICIPANTS

This phase 3, single-arm, open-label trial (ECOSPOR IV) was conducted at 72 US and Canadian outpatient sites from October 2017 to April 2022. Adults aged 18 years or older with recurrent CDI were enrolled in 2 cohorts: (1) rollover patients from the ECOSPOR III trial who had CDI recurrence diagnosed by toxin enzyme immunoassay (EIA) and (2) patients with at least 1 CDI recurrence (diagnosed by polymerase chain reaction [PCR] or toxin EIA), inclusive of their acute infection at study entry.

INTERVENTIONS

SER-109 given orally as 4 capsules daily for 3 days following symptom resolution after antibiotic treatment for CDI.

MAIN OUTCOMES AND MEASURES

The main outcomes were safety, measured as the rate of treatment-emergent adverse events (TEAEs) in all patients receiving any amount of SER-109, and cumulative rates of recurrent CDI (toxin-positive diarrhea requiring treatment) through week 24 in the intent-to-treat population.

RESULTS

Of 351 patients screened, 263 were enrolled (180 [68.4%] female; mean [SD] age, 64.0 [15.7] years); 29 were in cohort 1 and 234 in cohort 2. Seventy-seven patients (29.3%) were enrolled with their first CDI recurrence. Overall, 141 patients (53.6%) had TEAEs, which were mostly mild to moderate and gastrointestinal. There were 8 deaths (3.0%) and 33 patients (12.5%) with serious TEAEs; none were considered treatment related by the investigators. Overall, 23 patients (8.7%; 95% CI, 5.6%-12.8%) had recurrent CDI at week 8 (4 of 29 [13.8%; 95% CI, 3.9%-31.7%] in cohort 1 and 19 of 234 [8.1%; 95% CI, 5.0%-12.4%] in cohort 2), and recurrent CDI rates remained low through 24 weeks (36 patients [13.7%; 95% CI, 9.8%-18.4%]). At week 8, recurrent CDI rates in patients with a first recurrence were similarly low (5 of 77 [6.5%; 95% CI, 2.1%-14.5%]) as in patients with 2 or more recurrences (18 of 186 [9.7%; 95% CI, 5.8%-14.9%]). Analyses by select baseline characteristics showed consistently low recurrent CDI rates in patients younger than 65 years vs 65 years or older (5 of 126 [4.0%; 95% CI, 1.3%-9.0%] vs 18 of 137 [13.1%; 95% CI, 8.0%-20.0%]) and patients enrolled based on positive PCR results (3 of 69 [4.3%; 95% CI, 0.9%-12.2%]) vs those with positive toxin EIA results (20 of 192 [10.4%; 95% CI, 6.5%-15.6%]).

CONCLUSIONS AND RELEVANCE

In this trial, oral SER-109 was well tolerated in a patient population with recurrent CDI and prevalent comorbidities. The rate of recurrent CDI was low regardless of the number of prior recurrences, demographics, or diagnostic approach, supporting the beneficial impact of SER-109 for patients with CDI.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT03183141.

Manufacturing Process of SER-109, a Purified Investigational Microbiome Therapeutic, Reduces Risk of Coronavirus Transmission from Donor Stool

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may present risk to patients treated with donor-derived microbiome therapies when appropriate manufacturing controls and inactivation processes are lacking. We report that the manufacturing steps for SER-109, a purified investigational microbiome therapeutic developed to reduce risk of Clostridioides difficile recurrence, inactivate porcine epidemic diarrhea virus, a model coronavirus for SARS-CoV-2.

Adverse events of intestinal microbiota transplantation in randomized controlled trials: a systematic review and meta-analysis

Background

Intestinal microbiota transplantation (IMT) has been recognized as an effective treatment for recurrent Clostridium difficile infection (rCDI) and a novel treatment option for other diseases. However, the safety of IMT in patients has not been established.

Aims

This systematic review and meta-analysis was conducted to assess the safety of IMT.

Methods

We systematically reviewed all randomized controlled trials (RCTs) of IMT studies published up to 28 February 2021 using databases including PubMed, EMBASE and the Cochrane Library. Studies were excluded if they did not report adverse events (AEs). Two authors independently extracted the data. The relative risk (RR) of serious adverse events (SAEs) and common adverse events (CAEs) were estimated separately, as were predefined subgroups. Publication bias was evaluated by a funnel plot and Egger’s regression test.

Results

Among 978 reports, 99 full‐text articles were screened, and 20 articles were included for meta-analysis, involving 1132 patients (603 in the IMT group and 529 in the control group). We found no significant difference in the incidence of SAEs between the IMT group and the control group (RR = 1.36, 95% CI 0.56–3.31, P = 0.50). Of these 20 studies, 7 described the number of patients with CAEs, involving 360 patients (195 in the IMT group and 166 in the control group). An analysis of the eight studies revealed that the incidence of CAEs was also not significantly increased in the IMT group compared with the control group (RR = 1.06, 95% CI  0.91–1.23, P = 0.43). Subgroup analysis showed that the incidence of CAEs was significantly different between subgroups of delivery methods (P_(CAE) = 0.04), and the incidence of IMT-related SAEs and CAEs was not significantly different in the other predefined subgroups.

Conclusion

Currently, IMT is widely used in many diseases, but its associated AEs should not be ignored. To improve the safety of IMT, patients' conditions should be fully evaluated before IMT, appropriate transplantation methods should be selected, each operative step of faecal bacteria transplantation should be strictly controlled, AE management mechanisms should be improved, and a close follow-up system should be established.

Fecal microbiota transplantation: Uses, questions, and ethics

Fecal microbiota transplantation (FMT) has rapidly grown in notoriety and popularity worldwide as a treatment for both recurrent and refractory C. difficile infection (CDI), as well as for a myriad of other indications, with varying levels of evidence to justify its use. At present, FMT use in the U.S. has not received marketing approval from the U.S. Food and Drug Administration (FDA), but is permitted under "enforcement discretion" for CDI not responding to standard therapy. Meanwhile, the rising interest in the gut microbiome throughout mainstream media has paved the way for "do-it-yourself" (DIY) adaptations of the procedure. This access and unregulated use, often outside any clinical supervision, has quickly outpaced the medical community's research and regulatory efforts. While some studies have been able to demonstrate the success of FMT in treating conditions other than CDI-studies on ulcerative colitis have been particularly promising-little is still known about the treatmen's mechanism of action or long-term side effects. Likewise, screening of donor stool is in its early stages in terms of protocol standardization. In this paper, we explore the regulatory and ethical concerns that arise from the need to balance access to a nascent but promising innovative treatment with the need for research into its efficacy, risk profile, and long-term impact.

Gut Microbiota in Hypertension and Atherosclerosis: A Review

Gut microbiota and its metabolites such as short chain fatty acids (SCFA), lipopolysaccharides (LPS), and trimethylamine-N-oxide (TMAO) impact cardiovascular health. In this review, we discuss how gut microbiota and gut metabolites can affect hypertension and atherosclerosis. Hypertensive patients were shown to have lower alpha diversity, lower abundance of SCFA-producing microbiota, and higher abundance of gram-negative bacteria, which are a source of LPS. Animal studies point towards a direct role for SCFAs in blood pressure regulation and show that LPS has pro-inflammatory effects. Translocation of LPS into the systemic circulation is a consequence of increased gut permeability. Atherosclerosis, a multifactorial disease, is influenced by the gut microbiota through multiple pathways. Many studies have focused on the pro-atherogenic role of TMAO, however, it is not clear if this is a causal factor. In addition, gut microbiota play a key role in bile acid metabolism and some interventions targeting bile acid receptors tend to decrease atherosclerosis. Concluding, gut microbiota affect hypertension and atherosclerosis through many pathways, providing a wide range of potential therapeutic targets. Challenges ahead include translation of findings and mechanisms to humans and development of therapeutic interventions that target cardiovascular risk by modulation of gut microbes and metabolites.

The Efficacy and Safety of Fecal Microbiota Transplant for Recurrent Clostridium difficile Infection: Current Understanding and Gap Analysis

The leading risk factor for Clostridioides (Clostridium) difficile infection (CDI) is broad-spectrum antibiotics, which lead to low microbial diversity, or dysbiosis. Current therapeutic strategies for CDI are insufficient, as they do not address the key role of the microbiome in preventing C. difficile spore germination into toxin-producing vegetative bacteria, which leads to symptomatic disease. Fecal microbiota transplant (FMT) appears to reduce the risk of recurrent CDI through microbiome restoration. However, a wide range of efficacy rates have been reported, and few placebo-controlled trials have been conducted, limiting our understanding of FMT efficacy and safety. We discuss the current knowledge gaps driven by questions around the quality and consistency of clinical trial results, patient selection, diagnostic methodologies, use of suppressive antibiotic therapy, and methods for adverse event reporting. We provide specific recommendations for future trial designs of FMT to provide improved quality of the clinical evidence to better inform treatment guidelines.

International consensus conference on stool banking for faecal microbiota transplantation in clinical practice

Although faecal microbiota transplantation (FMT) has a well-established role in the treatment of recurrent Clostridioides difficile infection (CDI), its widespread dissemination is limited by several obstacles, including lack of dedicated centres, difficulties with donor recruitment and complexities related to regulation and safety monitoring. Given the considerable burden of CDI on global healthcare systems, FMT should be widely available to most centres.Stool banks may guarantee reliable, timely and equitable access to FMT for patients and a traceable workflow that ensures safety and quality of procedures. In this consensus project, FMT experts from Europe, North America and Australia gathered and released statements on the following issues related to the stool banking: general principles, objectives and organisation of the stool bank; selection and screening of donors; collection, preparation and storage of faeces; services and clients; registries, monitoring of outcomes and ethical issues; and the evolving role of FMT in clinical practice,Consensus on each statement was achieved through a Delphi process and then in a plenary face-to-face meeting. For each key issue, the best available evidence was assessed, with the aim of providing guidance for the development of stool banks in order to promote accessibility to FMT in clinical practice.

Comparison of Different Strategies for Providing Fecal Microbiota Transplantation to Treat Patients with Recurrent Clostridium difficile Infection in Two English Hospitals: A Review

Fecal microbiota transplant (FMT) has emerged as a highly efficacious treatment for difficult cases of refractory and/or recurrent Clostridium difficile infection (CDI). There have been many well-conducted randomized controlled trials and thousands of patients reported in case series that describe success rates of approximately 90% following one or more FMT. Although the exact mechanisms of FMT have yet to be fully elucidated, replacement or restoration of a 'normal' microbiota (or at least a microbiota resembling those who have never had CDI) appears to have a positive effect on the gut dysbiosis that is thought to exist in these patients. Furthermore, despite being aesthetically unappealing, this 'ultimate probiotic' is a particularly attractive solution to a difficult problem that avoids repeated courses of antibiotics. The lack of clarity about the exact mechanism of action and the 'active ingredient' of FMT (e.g., individual or communities of bacteria, bacteriophage, or bioactive molecules such as bile acids) has hindered the ability to produce a standardized and well-characterized FMT product. There is no standard method to produce material for FMT, and there are a multitude of factors that can vary between institutions that offer this therapy. Only a few studies have directly compared clinical efficacy in groups of patients who have been treated with FMT prepared differently (e.g., fresh vs. frozen) or administered by different route (e.g., by nasojejunal tube, colonoscopy or by oral administration of encapsulated product). More of these studies should be undertaken to clarify the superiority or otherwise of these variables. This review describes the methods and protocols that two English NHS hospitals independently adopted over the same time period to provide FMT for patients with recurrent CDI. There are several fundamental differences in the methods used, including selection and testing of donors, procedures for preparation and storage of material, and route of administration. These methods are described in detail in this review highlighting differing practice. Despite these significant methodological variations, clinical outcomes in terms of cure rate appear to be remarkably similar for both FMT providers. Although both hospitals have treated only modest numbers of patients, these findings suggest that many of the described differences may not be critical factors in influencing the success of the procedure. As FMT is increasingly being proposed for a number of conditions other than CDI, harmonization of methods and techniques may be more critical to the success of FMT, and thus it will be important to standardize these as far as practically possible.

How to: Establish and run a stool bank

BACKGROUND

Since 2013, several stool banks have been developed following publications reporting on clinical success of 'faecal microbiota transplantation' (FMT) for recurrent Clostridium difficile infections (CDI). However, protocols for donor screening, faecal suspension preparation, and transfer of the faecal suspension differ between countries and institutions. Moreover, no European consensus exists regarding the legislative aspects of the faecal suspension product. Internationally standardized recommendations about the above mentioned aspects have not yet been established.

OBJECTIVE

In 2015, the Netherlands Donor Feces Bank (NDFB) was founded with the primary aim of providing a standardized product for the treatment of patients with recurrent CDI in the Netherlands. Standard operation procedures for donor recruitment, donor selection, donor screening, and production, storage, and distribution of frozen faecal suspensions for FMT were formulated.

RESULTS AND DISCUSSION

Our experience summarized in this review addresses current donor recruitment and screening, preparation of the faecal suspension, transfer of the faecal microbiota suspension, and the experiences and follow-up of the patients treated with donor faeces from the NDFB.

Roles for Intestinal Bacteria, Viruses, and Fungi in Pathogenesis of Inflammatory Bowel Diseases and Therapeutic Approaches

Intestinal microbiota are involved in the pathogenesis of Crohn's disease, ulcerative colitis, and pouchitis. We review the mechanisms by which these gut bacteria, fungi, and viruses mediate mucosal homeostasis via their composite genes (metagenome) and metabolic products (metabolome). We explain how alterations to their profiles and functions under conditions of dysbiosis contribute to inflammation and effector immune responses that mediate inflammatory bowel diseases (IBD) in humans and enterocolitis in mice. It could be possible to engineer the intestinal environment by modifying the microbiota community structure or function to treat patients with IBD-either with individual agents, via dietary management, or as adjuncts to immunosuppressive drugs. We summarize the latest information on therapeutic use of fecal microbial transplantation and propose improved strategies to selectively normalize the dysbiotic microbiome in personalized approaches to treatment.

Fecal Microbiota-based Therapeutics for Recurrent Clostridium difficile Infection, Ulcerative Colitis and Obesity

The human gut microbiome is a complex ecosystem of fundamental importance to human health. Our increased understanding of gut microbial composition and functional interactions in health and disease states has spurred research efforts examining the gut microbiome as a valuable target for therapeutic intervention. This review provides updated insight into the state of the gut microbiome in recurrent Clostridium difficile infection (CDI), ulcerative colitis (UC), and obesity while addressing the rationale for the modulation of the gut microbiome using fecal microbiota transplant (FMT)-based therapies. Current microbiome-based therapeutics in pre-clinical or clinical development are discussed. We end by putting this within the context of the current regulatory framework surrounding FMT and related therapies.

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There is an increased understanding of gut microbial composition and functional interactions in health and disease states.

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FMT is effective for rCDI and has led to the development of fecal microbiota-based therapeutics for other indications.

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For stool-substitute therapies to enter mainstream medicine, further mechanistic studies, RCTs and regulations are needed.

A Novel Microbiome Therapeutic Increases Gut Microbial Diversity and Prevents Recurrent Clostridium difficile Infection

BACKGROUND

Patients with recurrent Clostridium difficile infection (CDI) have a ≥60% risk of relapse, as conventional therapies do not address the underlying gastrointestinal dysbiosis. This exploratory study evaluated the safety and efficacy of bacterial spores for preventing recurrent CDI.

METHODS

Stool specimens from healthy donors were treated with ethanol to eliminate pathogens. The resulting spores were fractionated and encapsulated for oral delivery as SER-109. Following their response to standard-of-care antibiotics, patients in cohort 1 were treated with SER-109 on 2 consecutive days (geometric mean dose, 1.7 × 10(9) spores), and those in cohort 2 were treated on 1 day (geometric mean dose, 1.1 × 10(8) spores). The primary efficacy end point was absence of C. difficile-positive diarrhea during an 8-week follow-up period. Microbiome alterations were assessed.

RESULTS

Thirty patients (median age, 66.5 years; 67% female) were enrolled, and 26 (86.7%) met the primary efficacy end point. Three patients with early, self-limiting C. difficile-positive diarrhea did not require antibiotics and tested negative for C. difficile at 8 weeks; thus, 96.7% (29 of 30) achieved clinical resolution. In parallel, gut microbiota rapidly diversified, with durable engraftment of spores and no outgrowth of non-spore-forming bacteria found after SER-109 treatment. Adverse events included mild diarrhea, abdominal pain, and nausea.

CONCLUSIONS

SER-109 successfully prevented CDI and had a favorable safety profile, supporting a novel microbiome-based intervention as a potential therapy for recurrent CDI.

Dietary Regulation of the Gut Microbiota Engineered by a Minimal Defined Bacterial Consortium

We have recently reported that Altered Schaedler Flora (ASF) can be used to durably engineer the gut microbiota to reduce ammonia production as an effective modality to reduce morbidity and mortality in the setting of liver injury. Here we investigated the effects of a low protein diet on ASF colonization and its ability to engineer the microbiota. Initially, ASF inoculation was similar between mice fed a normal protein diet or low protein diet, but the outgrowth of gut microbiota differed over the ensuing month. Notable was the inability of the dominant Parabacteroides ASF taxon to exclude other taxa belonging to the Bacteroidetes phylum in the setting of a low protein diet. Instead, a poorly classified yet highly represented Bacteroidetes family, S24-7, returned within 4 weeks of inoculation in mice fed a low protein diet, demonstrating a reduction in ASF resilience in response to dietary stress. Nevertheless, fecal ammonia levels remained significantly lower than those observed in mice on the same low protein diet that received a transplant of normal feces. No deleterious effects were observed in host physiology due to ASF inoculation into mice on a low protein diet. In total, these results demonstrate that low protein diet can have a pronounced effect on engineering the gut microbiota but modulation of ammonia is preserved.

Engineering the gut microbiota to treat hyperammonemia

Increasing evidence indicates that the gut microbiota can be altered to ameliorate or prevent disease states, and engineering the gut microbiota to therapeutically modulate host metabolism is an emerging goal of microbiome research. In the intestine, bacterial urease converts host-derived urea to ammonia and carbon dioxide, contributing to hyperammonemia-associated neurotoxicity and encephalopathy in patients with liver disease. Here, we engineered murine gut microbiota to reduce urease activity. Animals were depleted of their preexisting gut microbiota and then inoculated with altered Schaedler flora (ASF), a defined consortium of 8 bacteria with minimal urease gene content. This protocol resulted in establishment of a persistent new community that promoted a long-term reduction in fecal urease activity and ammonia production. Moreover, in a murine model of hepatic injury, ASF transplantation was associated with decreased morbidity and mortality. These results provide proof of concept that inoculation of a prepared host with a defined gut microbiota can lead to durable metabolic changes with therapeutic utility.

Fecal transplant policy and legislation

Fecal microbiota transplantation (FMT) has garnered significant attention in recent years in the face of a reemerging Clostridium difficile (C. difficile) epidemic. Positive results from the first randomized control trial evaluating FMT have encouraged the medical community to explore the process further and expand its application beyond C. difficile infections and even the gastrointestinal domain. However promising and numerous the prospects of FMT appear, the method remains limited in scope today due to several important barriers, most notably a poorly defined federal regulatory policy. The Food and Drug Administration has found it difficult to standardize and regulate the administration of inherently variable, metabolically active, and ubiquitously available fecal material. The current cumbersome policy, which classifies human feces as a drug, has prevented physicians from providing FMT and deserving patients from accessing FMT in a timely fashion, and subsequent modifications seem only to be temporary. The argument for reclassifying fecal material as human tissue is well supported. Essentially, this would allow for a regulatory framework that is sufficiently flexible to expand access to care and facilitate research, but also appropriately restrictive and centralized to ensure patient safety. Such an approach can facilitate the advancement of FMT to a more refined, controlled, and aesthetic process, perhaps in the form of a customized and well-characterized stool substitute therapy.