4 May 2023
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The FDA was busy last week! Off the back of the first approval for faecal microbiota transplant (FMT) in November 2022, the FDA approved Seres Therapeutics' orally administrated 'VOWST' capsule, and gave the first Phase 3 clinical trial go-ahead for a therapy based on the pooling of faecal matter.

Back in August 2021, the FDA imposed a clinical hold on MaaT Pharma’s pooled faecal therapy for the treatment of gastrointestinal acute graft-versus-host disease (GI-aGvHD). Now, 20 months later, the FDA is satisfied that MaaT has met all requirements to become the first therapy of its kind to enter Phase 3 clinical trials in the US, and lifted the clinical hold last week. And, just a few days later, Seres Therapeutics and Nestlé Health Sciences received approval of VOWST – the second microbiota-based therapeutic for recurrent C. difficile infection to be granted marketing approval in the USA.

Second over the line

As 2022 drew to a close, we reported that Rebiotix Inc. just pipped Seres and Nestlé over the line to be awarded the first FDA approval of a microbiome-based drug. Although both treat recurring C. difficile infection, Seres’ product VOWST (previously Ser-109) is now the first FMT with FDA approval to be delivered by oral administration, offering greater and more widespread access to patients, outside of a clinical setting. Already alive to the drawback of their rectally administered product Rebyota, Rebiotix have completed Phase 1 trials for RBX7455, an oral capsule alternative.

Entering the next phase of microbiota therapeutics

MaaT Pharma is a French biotech that has developed MaaT013 –a microbiota-based live biotherapeutic that involves the pooling of faecal matter from healthy donors. The benefits of pooling faecal matter, they argue, includes greater bacterial diversity in a standardised and scalable procedure. The therapy had been on clinical hold due to concerns over the mixing of faecal donations from multiple donors on a clinical scale, particularly during the pandemic. Now, this Microbiome Ecosystem Therapy (MET) is breaking ground towards US regulatory approval.

Graft versus Host Disease (GvHD) is a common and life-threating complication of hematopoietic stem cell transplantation (HSCT). Loss of gut diversity in HSCT patients, for example due to antibiotic or chemotherapy, increases the risk of GvHD. MaaT013, which also contains bacterial species that produce anti-inflammatory short-chain-fatty acids, is designed to treat GvHD by restoring a healthy microbiome.

The green light is a nod to the progress made through equivalent trials in Europe: MaaT013 is currently being assessed through a Phase 3 open-label study, taking place in multiple sites across the EU. This study, which is the first Phase 3 trial globally for a microbiome-based therapy in haemato-oncology, is assessing the safety and efficacy of the therapy in 75 patients with steroid-resistant Grade II-IV GI-aGvGD, who are also refractory to or intolerant of ruxolitinib treatment. Targeting this group of patients is crucial, considering the mortality rate of 70-80% in steroid-resistant aGvHD patients.

Positive Prospects

It’s exciting to see new microbiome-based therapies receiving positive opinions from regulatory bodies. Notably, Rebiotix Inc. and Seres Therapeutic’s approved therapies use quite different active ingredients to address recurring C. difficile infection, while MaaT Pharma’s Phase 3 product addresses an entirely different condition, GvHD. This suggests that microbiome-based therapies and diagnostics will make a wide-ranging impact on human healthcare in the near future.


About the authors

This article was co-authored by Alice Jefferies (lead), Edward Couchman, and Eliot Ward.

Blank Author Circle


Edward Couchman

Ed is experienced in drafting patent applications and prosecuting them around the world, with a particular focus on the fields of immunotherapy and enzyme technology. He is also experienced in carrying out freedom-to-operate (FTO) analysis for clients looking to bring new products to market. Ed works with a wide range of clients in the life sciences field from the UK and internationally, from university spin-outs and SMEs to multinational biotech corporations, and universities and research institutes.

Email: edward.couchman@mewburn.com



Eliot Ward Author Circle


Eliot Ward

Eliot handles a diverse client portfolio spanning the life sciences sector and a growing practice in the cross-over space between physics and biology. A skilled patent prosecutor, Eliot also has wide experience of drafting patent applications on breakthrough technologies, as well as leading offensive and defensive opposition proceedings post-grant. Eliot is also experienced in handling Freedom to Operate projects and in performing due diligence, which have led to the successful completion of high value transactions and investment rounds.

Email: eliot.ward@mewburn.com

Alice is a trainee patent attorney working in the Life Sciences sector. She has industrial experience, which was gained at a drug delivery start-up, and more recently has experience working in collaborative academic research at the Francis Crick Institute. Alice has a BSc in Biochemistry and a MSc in Immunology from Imperial College London. Her undergraduate research project focused on the use of potassium channel blockers as therapeutics for inflammatory diseases. During her Masters, Alice carried out a project investigating the impact of immunotherapy on the haematopoietic stem cell niche in Acute Myeloid Leukaemia.

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