The US Food and Drug Administration (FDA) has granted clearance to Direct Biologics’ investigational new drug application to initiate a Phase Ib/IIa clinical trial of ExoFlo to treat medically refractory perianal fistulising Crohn’s disease.

The placebo-controlled, multicentre, randomised, single-blind trial is expected to enrol 36 patients who will be divided into three treatment groups.

Escalating doses of the company’s therapeutic product candidate ExoFlo will be given to the three treatment groups and monitored for safety.

The trial will also assess efficacy using a combination of clinical examination and radiographic evaluation with pelvic MRI.

Evaluation of the number of adverse events and serious adverse events of one 15mL or 30mL treatment or two 30mL ExoFlo treatments is the trial’s primary endpoint.

Clinical and radiographic improvement are included as secondary endpoints while patient-reported disease outcomes are the tertiary/exploratory endpoints of the study.

Direct Biologics CEO Mark Adams said: “The expansion of our inflammatory bowel disease clinical programme into perianal fistulising Crohn’s disease underscores our commitment to providing treatment options to a patient population that suffers from chronic inflammatory disease.

“We look forward to the results of our Phase Ib/IIa study given that ExoFlo is the first extracellular vesicle product candidate to be evaluated in this patient population.”

Furthermore, the trial will assess ExoFlo’s efficacy in fistulising subtypes including patients with proctitis and numerous fistula tracts.

Direct Biologics chief medical officer Amy Lightner said: “We believe ExoFlo to be a promising therapeutic candidate for fistulising Crohn’s disease since it is designed as an off-the-shelf, cell-derived product with anti-inflammatory, immunomodulatory and tissue restoring properties.”