Moderna released positive preliminary data of its Phase I trail for COVID-19 vaccine candidate mRNA-1273 yesterday and will progress it into Phase II and Phase III trials—the latter set to start in July. The Phase I data showed that all 45 participants across the study’s three dose levels produced antibodies of the virus by day 15 following dosing, with eight of the participants in two of the dose levels reaching or exceeding neutralizing antibody titers generally seen in convalescent sera.
The NIH’s National Institute of Allergy and Infectious Diseases (NIAID) is leading the Phase II trial (NCT04283461) of mRNA-1273, a novel lipid nanoparticle (LNP)-encapsulated mRNA vaccine encoding for a prefusion stabilized form of the Spike (S) protein.
The NIAID-led study is assessing three doses of the vaccine in healthy participants ages 18-55: 25 µg and 100 µg, based on two doses as of day 43; and 250 µg, based on one dose as of day 29.
All participants across all three dose levels seroconverted by day 15 after a single dose, Moderna said. At day 43, two weeks following the second dose, levels of binding antibodies for the 15 participants dosed at the 25 µg level were at levels seen in blood samples from people who have recovered from COVID-19. At day 43, 10 participants at the 100 µg level showed levels of binding antibodies that significantly exceeded the levels seen in convalescent sera.
Samples are not yet available for the remaining participants, Moderna said.
Consistent with the binding antibody data, mRNA-1273 vaccination elicited neutralizing antibodies in the first four participants in each of the 25 µg and 100 µg dose level cohorts—the only participants for which neutralizing antibody data was available—as measured by plaque reduction neutralization assays against live SARS-CoV-2.
Levels of neutralizing antibodies at day 43 were at or above levels generally seen in convalescent sera, the company said.
The first participant in the Phase I study was dosed on March 16, 63 days from sequence selection to Phase 1 study dosing….
