Direct Biologics has announced additional positive data from a Phase II trial investigating its therapeutic product ExoFlo in hospitalised Covid-19 patients with moderate-to-severe acute respiratory distress syndrome (ARDS).

ExoFlo comprises exosomes isolated from human bone marrow mesenchymal stem (MSCs) and is developed based on extracellular vesicles (EVs) platform technology.

The US-based biotech published the new data in a peer-reviewed medical journal, CHEST. The analysis showed an overall mortality rate of 61% amongst all subjects. The post-hoc subgroup analyses demonstrated that subjects with respiratory failure had a 60-day mortality rate of 50% in the placebo group and 19.2% in the ExoFlo-15 group.

Patients who met the modified Berlin criteria for moderate-to-severe ARDS had a 60-day mortality rate of 72.7% in the placebo group and 30.8% in the ExoFlo-15 cohort. Additionally, the number of ventilator-free days (VFDs) in the ExoFlo-15 arm improved compared to placebo.

The Phase II trial (NCT04493242) enrolled 102 patients with Covid-19 associated moderate-to-severe ARDS in five sites across the US. Subjects were randomised into placebo, 10mL or 15mL ExoFlo cohorts and received the interventions on the first and fourth days.

The primary endpoint measured the all-cause 60-day mortality rate. Secondary endpoints investigated overall mortality, the incidence of treatment-emergent serious adverse events, the proportion of discharged patients, time-to-hospital discharge and VFDs.

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In April, Direct Biologics reported positive safety and efficacy results from its expanded access programme investigating ExoFlo in Covid-19 patients with ARDS. This trial recruited patients who could not participate in the other trials conducted by the company.

The results showed no serious adverse events, with one Grade 1 adverse event reported that was related to the infusion site.

In the same month, the US Food and Drug Administration (FDA) granted a regenerative medicine advanced therapeutic (RMAT) designation to ExoFlo based on preliminary results. The designation can accelerate the approval of potential generative medical products that show clinical signs.

ExoFlo in Phase III

Direct Biologics is currently recruiting patients for a Phase III trial (NCT05354141). In this trial, the company is casting a wider net and looking for 320 subjects with ARDS from any underlying aetiology.

The trial will investigate three intravenous doses of ExoFlo 15mL compared to a placebo, with all patients receiving standard of care. The primary endpoint will also measure a 60-day all-cause mortality rate. Along with additional exploratory endpoints, the secondary outcome measures will include VFDs, oxygen-free days and ICU-free days.

Additionally, the trial will investigate the efficacy of ExoFlo in ARDS subtypes to better understand the disease process.