Twelve of nineteen patients on Microbiotica's MB310 reached clinical remission in a 29-person Phase 1b trial. Three of ten on placebo did. On 16 October 2026, that 63.2% versus 30.0% split raised £36 million ($48 million) in the first close of a Series C led by the British Business Bank.
The money is earmarked for one thing: a Phase 2 trial of MB310 in ulcerative colitis, an inflammatory bowel disease that affects up to five million people worldwide. Microbiotica is a private Cambridge company spun out of the Wellcome Sanger Institute in 2016. Its lead asset is a once-daily capsule of eight live gut bacteria.
The round is a wager that a small, symptom-scored remission signal will hold at the stage where two better-funded microbiome programmes already failed.
The headline 63.2% comes from a partial Mayo score that excludes endoscopic findings; the registered primary endpoint includes them.
MB310's difference is a defined eight-strain consortium plus a genomics platform, not a new drug class.
What the £36 million actually prices
The round was led by the British Business Bank, the UK government's economic development bank. Tencent, IP Group, Cambridge Innovation Capital, Flerie Invest and Seventure Partners participated. Every existing Series B investor followed on.
IP Group disclosed its own slice: £4 million for an undiluted 16.4% holding valued at £24.1 million. That is the clearest public mark on the company. IP Group chief executive Greg Smith called the MB310 results "a strong foundation for its next stage of development."
Microbiotica is not starting from scratch. It raised £50 million in a 2022 Series B and had more than £62 million in equity by February 2026, according to European Biotechnology. It also has a Genentech alliance covering microbiome-based biomarkers and therapeutics in inflammatory bowel disease.
The Series C is a first close, not a final one. That structure leaves room for more capital if the Phase 2 design attracts a partner, and it lets existing investors set the price before the trial's cost becomes public.
A field that has already buried two Phase 2s
Vedanta Biosciences ran the closest comparable experiment. Its VE202, a mix of 16 bacterial strains, failed to beat placebo on endoscopic response in a 114-patient Phase 2 called COLLECTiVE202. The company announced the miss in August 2025 and terminated the study. Vedanta cut 20% of its staff.
As a field, we have not yet succeeded in making a meaningful impact for people with IBD through microbiome-based approaches, but every study moves us closer to that goal.— Bernat Olle, chief executive, Vedanta Biosciences
Seres Therapeutics offers the second warning. Its SER-287, made from donor-derived bacteria, missed clinical remission in a 203-patient Phase 2b in July 2021 even though the bacteria colonized patients' guts. Engraftment and efficacy turned out to be separate problems.
| Program | Phase 2 size | Primary endpoint | Result |
|---|---|---|---|
| Vedanta VE202 | 114 | Endoscopic response | ✗ Missed; study terminated |
| Seres SER-287 | 203 | Clinical remission | ✗ Missed at Phase 2b |
| Microbiotica MB310 | Phase 1b: 29 | Phase 2: undisclosed | ◐ Phase 1b signal; Phase 2 pending |
Company releases and ClinicalTrials.gov records, 2021–2026
One microbiome product has cleared the regulatory bar. Seres' Vowst won US approval in 2023 for recurrent Clostridioides difficile infection and is now commercialized by Nestlé Health Science. That approval sits in an infection setting, not in ulcerative colitis, where the immune mechanism is harder to isolate.
The capsule and the platform
MB310 contains eight specific live gut commensal strains in a once-daily oral capsule. Patients first received vancomycin, 125 mg four times a day for five days, followed by a two-day washout. The antibiotic clears space in the gut before the consortium arrives. Treatment ran for 12 weeks.
The strains were selected from a fecal-transplant study run with the University of Adelaide. Microbiotica picked bacteria that colonized patients and were associated with clinical response. In COMPOSER-1, the strains took hold within the first week and all eight persisted through three months of follow-up.
The therapeutic claim is epithelial repair. Microbiotica says MB310 promotes repair of the gut barrier and produces anti-inflammatory effects without suppressing the immune system. That mechanism would make it combinable with existing advanced therapies, which is where the commercial case gets interesting.
The platform behind it combines a microbial culture collection, a proprietary human reference-genome database, bioinformatics and machine learning. The company's pitch is that it selects strains from clinical outcomes rather than from lab screens. MB097, a second asset, is in a Phase 1b extension with KEYTRUDA in advanced melanoma and has also reported positive early data.
The denominator problem
COMPOSER-1 enrolled 29 adults with mild-to-moderate disease across sites in the UK, Austria, Bulgaria, Poland and Spain. It started on 27 September 2024 and completed on 8 January 2026. Nineteen patients received MB310 and ten received placebo.
The 63.2% versus 30.0% remission figures are partial Mayo scores, which rate stool frequency, rectal bleeding and a physician's global assessment but omit endoscopic findings. ClinicalTrials.gov lists the trial's primary endpoint as clinical remission at Day 91 on a Modified Mayo Score of 0–2 with an endoscopic subscore of 0 or 1. The company says the study met its primary and secondary endpoints; the published split is the symptom-based version.
Partial Mayo scores are common in early ulcerative colitis trials because they are cheap and fast. They are also easier to move than endoscopic scores. A patient can feel better while their mucosa still shows inflammation, and payers increasingly want to see the mucosa.
The small denominator compounds the problem. Twelve responders out of nineteen is a strong proportion, but the confidence band around it is wide. A handful of patients changing sides would move the rate by double digits. Phase 1b was designed mainly to test safety and engraftment, and it met that objective with no safety issues reported.
None of this makes the result false. It makes it preliminary. The Phase 2 the Series C funds is the first test with enough patients and a strong enough endpoint to separate a real drug effect from a small-sample artifact.
What Phase 2 has to show
Microbiotica has said the next study will be randomized, double-blind and placebo-controlled. In February 2026 it described a Phase 2/3 testing MB310 alongside anti-inflammatory or immune-modulating drugs given to induce remission. The company has not disclosed the target enrollment, the endpoint or the budget.
Those omissions are normal at this stage. They also mean investors are pricing a design that does not yet exist in public. The £36 million is enough to start a mid-stage colitis trial; whether it is enough to finish one depends on size, sites and whether a partner joins.
The strategic upside sits in combination. If MB310 repairs the barrier without immune suppression, it could be layered onto biologics or JAK inhibitors rather than competing with them. That is a larger market and a cheaper development path than a standalone monotherapy. It is also unproven.
One European rival is reportedly a stage ahead in ulcerative colitis, according to European Biotechnology. Microbiotica is not racing to be first. It is racing to be validated before the capital window closes.
What would make the Phase 2 readout believable?
Probability: 45% — the Phase 1b safety and engraftment data support a real effect, but the field's two prior Phase 2 failures used endoscopic endpoints that symptom scores do not predict.
🟢 Optimistic scenario (30%)
Consequence: the £36 million looks cheap, and Microbiotica moves from platform story to clinical-stage company with a priced pipeline.
🟡 Base scenario (50%)
Consequence: the science survives, the timeline slips, and the next financing is priced on the colitis data rather than the platform.
🔴 Pessimistic scenario (20%)
Consequence: the colitis programme is shelved or partnered at a discount, and value shifts to MB097 and the platform's biomarker business.
The bet, stated plainly
Microbiotica has real assets: a defined consortium, a plausible mechanism, a second clinical programme and a syndicate willing to fund a binary trial. It also has a 29-patient dataset scored without endoscopy and two competitors that failed the next test.
The Series C does not resolve that tension. It buys the right to test it. For investors, the question is whether a 63.2% symptom response in nineteen patients is enough evidence to underwrite a Phase 2 in a field that has already produced two expensive negatives.
Microbiotica's own investors answered yes. The Phase 2 will tell the rest of the market whether they were early or wrong.