Infex Therapeutics backs RESP‑X antibody, MET‑X metallo‑beta‑lactamase inhibitor to tackle resistant Gram‑negatives
This article covers Infex Therapeutics, a biotech startup, closing a £4.3m growth funding round to advance a pipeline of anti-infectives targeting antimicrobial resistance. The funding is intended to progress RESP-X following a Phase 2a trial, expand the MET-X programme to counter metallo-beta-lactamase-mediated resistance and support preclinical work on a BamA inhibitor, targeting hard-to-treat Gram-negative infections and patients with Pseudomonas aeruginosa-colonised non-cystic fibrosis bronchiectasis.
Infex Therapeutics, a biotech startup based in Alderley Park, has closed a £4.3 million growth funding round to advance a pipeline of anti-infectives aimed at antimicrobial resistance (AMR). The cash will underwrite progression of its lead candidate RESP-X after a Phase 2a trial, expansion of its MET-X resistance-bypass programme and further preclinical work on a BamA inhibitor — developments that matter because options for drug-resistant Gram-negative infections remain limited.
Why it matters
Antimicrobial resistance is a recognised public-health emergency and Gram-negative pathogens such as Pseudomonas aeruginosa and Enterobacterales present acute treatment challenges. RESP-X targets patients with P. aeruginosa-colonised non-cystic fibrosis bronchiectasis (NCFB), a group with recurrent, potentially severe respiratory exacerbations and no licensed preventative therapy. MET-X aims to restore the activity of existing beta-lactam antibiotics against metallo-beta-lactamase-producing pathogens, a mechanism driving many recent drug failures. Progress across both could change treatment options for hard-to-treat infections.
Inside the product
RESP-X
- RESP-X is an anti-virulence monoclonal antibody in-licensed from Shionogi, tested in a Phase 2a trial for safety, dosing and early efficacy in Pa-colonised NCFB patients. The company says data are encouraging and will be presented at the American Thoracic Society 2026 conference.
MET-X
- MET-X is a metallo-beta-lactamase (MBL) inhibitor intended to work alongside beta-lactam antibiotics such as meropenem to overcome a key resistance mechanism in Gram-negative Enterobacterales. Infex has an exclusive arrangement for MET-X clinical development in India with Venus Remedies Ltd; Infex retains development and commercial rights outside India.
BamA inhibitor programme
- The company is also progressing a BamA inhibitor in collaboration with Justus-Liebig-University Giessen, supported by PACE (Pathways to Antimicrobial Clinical Efficacy) funding. BamA is a novel outer membrane assembly protein target that has previously been considered difficult to drug.
ATS 2026 presentation
- Infex will present RESP-X Phase 2a results in a late-breaking abstract at ATS 2026 on 20 May 2026 (Session D92, Orange County Convention Center, 12.48 PM ET). The abstract title and author list are listed in the company materials.
Who are the investors?
The round is led by British venture capitalist Jon Moulton, with participation from the GM&C Life Sciences Fund (managed by Catapult Ventures) and existing high net worth investors. The funding is earmarked to prepare RESP-X for further clinical development, expand MET-X for drug-resistant infections and advance preclinical programmes including the BamA inhibitor.
In the announcement, Dr Peter Jackson, CEO of Infex Therapeutics, said:
We are delighted to secure this investment led by Jon Moulton, with support from the Greater Manchester and Cheshire Lifescience Investment Fund and our existing investors.
This funding represents strong validation of our progress in developing novel anti-infectives to address the critical global threat of antimicrobial resistance. It enables us to advance RESP-X toward later stage clinical development, expand our MET-X programme, and advance our broader preclinical pipeline of first-in-class approaches targeting highly resistant Gram-negative pathogens.
In the announcement, Jon Moulton, Chair of Infex Therapeutics, said:
We have supported Infex from the beginning and continue to be impressed by the Company’s scientific progress and strategic execution. Infex’s lead programme RESP-X is approaching a critical inflection point with upcoming phase IIa results, and we strongly believe it will be a life-changing future first therapy for NCFB patients with drug resistant Pa colonisation. This additional investment reflects our strong conviction in both the team and its innovative approach to tackling antimicrobial resistance.
In the announcement, Nick Wright, CEO of Catapult Ventures which manages the GM&C Life Sciences Fund, said:
Infex Therapeutics has made excellent scientific progress since we first invested several years ago. The company has clearly established itself as a world leader in the AMR and related space and the data it is generating is very compelling.
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Founder perspective
Infex frames the funding as validation of scientific progress and a bridge to later-stage clinical work for RESP-X, while enabling MET-X development and continued preclinical discovery. The company is positioning RESP-X not only for NCFB but for potential expansion into cystic fibrosis, COPD and acute hospital infections.
The bigger picture
The investment underscores continued interest from biotech investors in AMR-focused approaches that pair novel biology with strategies to restore existing antibiotics. Infex’s partnerships — an in-license from Shionogi, a clinical development deal with Venus in India and a German university collaboration supported by PACE — illustrate the cross-border, multi-stakeholder model common in antibiotic R&D. As RESP-X data become public at ATS, the results will be an important signal for follow-on capital and for the UK and European effort to rebuild a patentable antibiotics pipeline in the face of rising resistance.
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