Microbiotica Announces Positive Results from its Phase 1b Trial (MELODY-1) of MB097, a Precision Microbiome Co-Therapy in Advanced Melanoma

MB097 used in combination with MSD’s anti-PD-1 therapy, KEYTRUDA® (pembrolizumab)

CAMBRIDGE, United Kingdom, May 18, 2026 (GLOBE NEWSWIRE) -- Microbiotica, a clinical-stage biopharma company developing a pipeline of oral precision microbiome medicines called live biotherapeutic products (LBPs), announces that all primary and secondary objectives were met in its advanced melanoma (MELODY-1) Phase 1b trial.

MELODY-1 was an international Phase 1b study to evaluate the safety and tolerability of MB097 given in combination with KEYTRUDA® (pembrolizumab), MSD’s anti-PD-1 therapy, in patients with advanced melanoma who demonstrated primary resistance to anti-PD-1 therapy. The trial recruited 41 patients at clinical centres in the UK, France, Italy, and Spain.

MB097 could be administered safely in combination with KEYTRUDA with no serious adverse events (SAEs) related to MB097
The nine bacterial strains contained in MB097 demonstrated robust engraftment after dosing, with enhanced engraftment following vancomycin preconditioning
Encouraging signals of efficacy were seen in this difficult to treat, primary-refractory advanced melanoma patient population, suggesting that microbiome modulation with MB097 may overcome resistance to anti-PD-1 therapy.

Detailed results of the study will be presented at a scientific conference during 2026.

Commenting on the study results, Dr Pippa Corrie from Cambridge University Hospitals NHS Foundation Trust, the National Co-ordinating Investigator for the MELODY-1 study said, “There is increasing evidence that the microbiome plays a crucial role in patients’ response to immune checkpoint inhibitors. Clinical benefit has been reported with Faecal Microbiota Transplantations (FMT), while MB097 capsules taken orally each day affords an easy and reproducible way of modifying the microbiome. The MELODY-1 study results show that MB097 is well tolerated, with encouraging early signs of efficacy in a very difficult to treat metastatic melanoma patient population with primary resistance to anti-PD-1 based immunotherapy, in whom there is a significant unmet need.”

In this first-in-human, randomised open-label clinical trial, all patients received MB097 and pembrolizumab for up to six months. Half of the participants also received vancomycin before starting the co-therapy to determine whether it helps the bacterial strains in MB097 engraft in the gut more efficiently. Participants benefiting from the treatment at the end of the initial six-month period have entered an extension study and can continue to receive pembrolizumab for up to an additional 18 months. The results of this extension phase will be reported in due course.

MB097 is a once daily, orally administered LBP consisting of a defined consortium of nine strains of commensal bacteria designed to enhance the efficacy of immune checkpoint inhibitors (ICIs). The MELODY-1 study is designed to investigate the safety, tolerability, and initial signals of efficacy of MB097 in advanced (metastatic) melanoma, in combination with KEYTRUDA® (pembrolizumab), MSD’s (Merck & Co., Inc., Rahway, NJ, USA) anti-PD-1 therapy, in patients with cutaneous melanoma who have failed to respond to immunotherapies (study identifiers NCT06540391; MSD KEYNOTE-E75; 023-507377-17). MSD has supplied KEYTRUDA to Microbiotica.

Dr Robert Tansley, Microbiotica’s Chief Medical Officer, said, “We are encouraged by these positive data on safety and engraftment. With early signs of efficacy, we look forward to further analysis from the trial respondents. The results provide the foundation to proceed to larger controlled studies in a broader melanoma patient population and we are excited by the potential to deliver a new option to maximise patients’ potential to respond to anti-PD-1 therapy.”

Tim Sharpington, Microbiotica’s CEO added, “This is our second clinical trial to report positive results, following the success of our Phase 1b study of MB310 in ulcerative colitis earlier this year. This is further validation of our clinic-first discovery platform and precision microbiome medicine development.”

Notes to Editors

KEYTRUDA^® is a registered trademark of Merck Sharp & Dohme LLC, a subsidiary of Merck & Co., Inc., Rahway, NJ, USA.

About Melanoma – MB097 and the MELODY-1 study

Melanoma is a life-threatening skin cancer that can spread to other parts of the body in its advanced stages. PD-1 inhibitor immunotherapies have revolutionised cancer treatment and are now commonly used to treat melanoma. However, new treatment options are still needed to extend the benefit to patients for whom immunotherapies do not work (treatment-resistant patients). This can be up to 50% of all advanced melanoma patients. There is a growing body of evidence demonstrating that the composition of the gut microbiome can significantly influence a patient’s ability to respond to immunotherapy. Faecal transplants from responding patients have been shown to reverse checkpoint inhibitor resistance (Davar et al; 2021; Baruch et al; 2021)

The bacterial strains in MB097 were identified by analysing the microbiome of patients in multiple studies of ICIs in melanoma, including the MELRESIST study carried out with the company’s collaborators at Cambridge University Hospitals, UK. Collectively, the MB097 bacterial consortium provides microbiome signalling that appears to be needed for ICI response.

About Microbiotica

Microbiotica is a private, clinical-stage, biopharma company developing a pipeline of oral precision microbiome medicines called live biotherapeutic products (LBPs) with lead programmes in immuno-oncology and inflammatory bowel disease. The company has a clinic-led, purpose-built, proprietary, microbiome profiling platform to support drug discovery based on clinical data, which enables precision identification of bacteria associated with favourable clinical trial outcomes in specific patient populations. The company has significant expertise in microbiology, bioinformatics, translational biology and LBP manufacturing and development.

The Company is creating a novel pipeline of programmes:

in immuno-oncology
- MB097 for advanced melanoma, currently in a Phase 1b extension phase having reported a positive outcome with all study objectives met. The company has a clinical trial supply agreement with MSD (Merck & Co., Inc., Rahway, NJ, USA) for use of KEYTRUDA in evaluating MB097 in melanoma patients with primary resistance to anti-PD-1 immunotherapy. MB310 was developed in collaboration with the University of Adelaide.
- a major partnership with Cancer Research UK and Cambridge University Hospitals
in inflammatory bowel disease
- MB310 for ulcerative colitis, which has demonstrated excellent clinical efficacy and safety in a Phase 1b study.

Spun out of the Wellcome Sanger Institute in 2016, the Company is based in purpose-built facilities at the Chesterford Research Park near Cambridge, UK. Microbiotica has raised more than £62 million equity investment, including a £50 million Series B, with venture investors including British Patient Capital, Cambridge Innovation Capital, Flerie Invest, IP Group plc, Seventure Partners and Tencent. The company has also received financial support from the US-based Crohn’s and Colitis Foundation.

For more information, please visit www.microbiotica.com, and follow us on LinkedIn.

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