Moderna has reported positive interim results from the Phase I clinical trial of its Covid-19 vaccine candidate, mRNA-1273, led by the National Institutes of Health (NIH)’s National Institute of Allergy and Infectious Diseases (NIAID).
The company recorded immunogenicity data for the 25µg and 100µg dose levels following two doses (day 43) and at the 250µg dose level after one dose (day 29).
Results showed dose dependent increases in immunogenicity across the three dose levels, as well as between prime and boost with the 25µg and 100µg dose levels.
Participants across the three dose levels seroconverted by day 15 after a single dose. At day 43, two weeks after the second dose, levels of binding antibodies in subjects on 25µg dose were the same as those seen in blood samples of recovered Covid-19 patients.
Meanwhile, the 100µg arm’s levels of binding antibodies were found to have significantly exceeded those observed in recovered patients.
The trial enrolled patients aged 18-55 years.
Neutralising antibody data is available for the initial four participants in each of the 25µg and 100µg dose level cohorts.
mRNA-1273 is said to have induced neutralising antibodies in all participants and, at day 43, the levels were at or above those seen in recovered patients.
The Covid-19 vaccine candidate was generally safe and well-tolerated. The safety profile of the drug is consistent with that found in previous infectious disease vaccine clinical trials by the company.
Moderna chief medical officer Tal Zaks said: “These interim Phase I data, while early, demonstrate that vaccination with mRNA-1273 elicits an immune response of the magnitude caused by natural infection starting with a dose as low as 25µg.
“When combined with the success in preventing viral replication in the lungs of a pre-clinical challenge model at a dose that elicited similar levels of neutralising antibodies, these data substantiate our belief that mRNA-1273 has the potential to prevent Covid-19 disease and advance our ability to select a dose for pivotal trials.”
Based on the interim Phase I results, the company will update its Phase II trial to assess two dose levels of 50µg and 100µg. The Phase I study is also being amended to include a cohort of 50µg dose level.