eFFECTOR Therapeutics has reported positive top-line data from its Phase Ib clinical trial of zotatifin to treat Covid-19.

The potent and sequence-selective small molecule eIF4A inhibitor zotatifin demonstrated favourable safety results and positive trends in multiple antiviral activity measures.

In the double-blind, randomised, placebo-controlled dose escalation study of zotatifin, 27 subjects received the therapy at doses ranging from 0.01 to 0.035 mg/kg, and nine were given a placebo.

Initially, one subject received zotatifin and one received a placebo by intravenous administration.

By sub-cutaneous injection, all other subjects in the trial received the study drug.

Subjects enrolled in the trial had mild or moderate Covid-19 and were positive for SARS-CoV-2 RNA or antigens within seven days after they were randomised.

eFFECTOR conducted the trial in partnership with the University of California, San Francisco’s (UCSF) Quantitative Biosciences Institute (QBI).

Assessment of zotatifin’s safety in subjects with mild-to-moderate Covid-19 was the primary objective of the trial.

At all doses, zotatifin was found to be generally well tolerated and reactions at injection sites from the sub-cutaneous route was the only adverse event that showed a potential relationship to the dose.

The trial’s secondary and exploratory objectives included assessment of antiviral activity in saliva and nasal samples, and pharmacokinetics (PK).

eFFECTOR also announced preclinical results where zotatifin was found to be active against several Covid-19 isolates and other coronaviruses.

eFFECTOR Therapeutics president and CEO Steve Worland said: “We’re pleased with the positive trends in antiviral activity seen in this small study, especially in the time to achieve undetectable virus levels in saliva.

“Coupled with the fact that zotatifin was generally well tolerated and achieved target drug levels via a single sub-cutaneous administration, we believe these results, as well as the potency and breadth of antiviral activity seen in preclinical studies, position zotatifin as an attractive option for further development to treat Covid-19, including disease due to evolving variants, and diseases that may emerge due to other RNA viruses.”