Anti-infectives specialist Infex Therapeutics Holdings plc announced on Monday that it has dosed the first patient in a Phase IIa clinical trial of RESP-X, an anti-virulence antibody therapy designed to treat Pseudomonas aeruginosa (Pa) infections in patients with non-cystic fibrosis bronchiectasis (NCFB). Pa infections are a significant driver of severe, recurrent exacerbations in NCFB patients, for which there are currently no approved preventative treatments.

The trial, conducted at Liverpool University NHS Foundation Trust's NIHR Clinical Research Facility, will assess 12 patients in a double-blind, placebo-controlled study. The study aims to evaluate safety, initial efficacy, and optimal dosing of RESP-X at 6mg/kg and 10mg/kg doses, ahead of a larger Phase IIb efficacy trial.

RESP-X is a first-in-class monoclonal antibody that targets Pa infections by blocking the bacteria's type III secretion system (T3SS), a key mechanism in causing tissue damage and evading the immune system. Unlike antibiotics, RESP-X does not kill bacteria directly but allows the immune system to control the infection more effectively.

Approximately 30% of NCFB patients, out of a global population of six million, suffer from chronic Pa colonisation. Despite this, no licensed therapies currently exist to prevent exacerbations caused by Pa in these patients. There is potential for RESP-X to be extended to treat other conditions like cystic fibrosis, COPD, and hospital-acquired pneumonia.

RESP-X was in-licensed from Shionogi and represents a critical advancement in treating drug-resistant pathogens like Pa, identified by the World Health Organization as a major threat to public health.