ARCA biopharma has reported topline results from Phase IIb ASPEN-COVID-19 clinical trial of its therapy rNAPc2 (AB201) to potentially treat hospitalised Covid-19 patients. 

A highly selective tissue factor inhibitor, rNAPc2 has anti-inflammatory, anticoagulant and potential antiviral effects.

The multicentre, randomised trial assessed two doses of rNAPc2 versus standard of care of heparin in 160 Covid-19 patients in hospital with increased D-dimer levels. 

A biomarker, D-dimer is utilised to evaluate coagulation activation, which is usually raised in hospitalised Covid-19 patients and is linked to adverse clinical outcomes. 

Heparin is an anticoagulant administered to hospitalised Covid-19 patients in the US.

The variation in D-dimer level from baseline to day eight versus heparin is the primary endpoint of the trial. 

The company concluded subject enrolment in the trial of rNAPc2 for Covid-19, in December last year.

Findings showed that for the complete cohort of Covid-19 patients in the hospital setting, the pooled lower and higher rNAPc2 dose arms showed a decline compared to baseline in D-dimer levels of 16.8% versus 11.2% in the heparin arm.

Even though both doses showed a treatment benefit in trial subjects, none of the doses attained statistical significance for the primary efficacy endpoint versus heparin.

Variation in D-dimer levels from baseline at day eight in the per protocol analysis showed a decline of 28.7% in the rNAPc2 dose pooled group versus a rise of 1.1% in subjects who received heparin.

Assessment on an adapted WHO COVID-19 Severity Scale showed that the D-dimer levels reduced from baseline in mild patients but rose in severe patients in the heparin group while no changes were reported in the rNAPc2 arms.

A numerical imbalance favouring rNAPc2 treatment, which was not significant, was reported on the secondary endpoints assessing thrombotic events and time-to-recovery.

In addition, rNAPc2 was demonstrated to be well-tolerated at both the tested doses without any serious treatment-associated adverse events noted.

ARCA biopharma president and CEO Dr Michael Bristow said: “At this time, ARCA is not planning further clinical development of rNAPc2 in Covid-19 in a direct superiority comparison to heparin design. 

“However, we believe the safety margin and apparent efficacy at the lower dose would not preclude a study design evaluating a prophylactic heparin-rNAPc2 combination.”