Immunic has started enroling participants in a Phase IIb clinical trial of its drug candidate, IMU-838, combined with oseltamivir (Tamiflu) to treat moderate to severe Covid-19.

IMU-838 is a selective oral dihydroorotate dehydrogenase (DHODH) inhibitor while oseltamivir is a neuraminidase inhibitor.

Named IONIC, the prospective, randomised, parallel-group, open-label Phase IIb trial will assess the safety and efficacy of the combination therapy in around 120 adult patients.

The investigator-sponsored study is supported by the sponsor’s Trial Management Unit (TMU) and University Hospitals Coventry and Warwickshire (UHCW) NHS Trust.

IONIC trial chief investigator Ramesh Arasaradnam said: “Recent third-party research has highlighted the powerful synergy between direct antiviral drugs and DHODH inhibitors in preclinical models.

“We believe that the combination of oseltamivir, which is a licensed drug in the UK, and IMU-838, may offer a promising approach for the treatment of severe viral infections, including mid-to-late-stage Covid-19 patients.”

In preclinical studies, IMU-838 showed activity against SARS-CoV-2, the virus that causes Covid-19. The drug candidate was able to inhibit replication of clinical isolates of the virus.

Cellular assays found that this antiviral activity was at concentrations well below the blood concentrations of IMU-838 dosing regimens evaluated in ongoing and previous trials.

The IONIC trial will compare the combination therapy to oseltamivir alone for 14 consecutive days. All patients are eligible for standard-of-care therapy throughout the the study duration.

Immunic CEO and president Daniel Vitt said: “We also believe that this trial can provide valuable insights as to whether the host cell-based antiviral mechanism of IMU-838 has a synergistic effect with a direct antiviral drug in order to provide a combination treatment approach for Covid-19.”

To support the IONIC trial, the UHCW NHS Trust secured funding from medical research charity LifeArc.

Last month, Immunic began dosing patients in the Phase II CALVID-1 trial of IMU-838 in Covid-19 patients.