Preclinical results for MRT5500, the COVID-19 vaccine candidate under development by the two companies, demonstrated a favorable immune response profile against SARS-CoV-2, the virus causing coronavirus, which supports the selection of the candidate for clinical development.
Key findings in the preclinical studies found that MRT5500 has the potential to elicit neutralizing antibodies against SARS-CoV-2. Four dose levels were assessed in mice at 0.2, 1, 5 and 10 µg per dose, using a two-dose vaccination schedule, administered three weeks apart.
MRT5500-induced, dose-dependent levels of binding antibodies and neutralizing antibodies specific to the SARS-CoV-2 spike protein, while 100% seroconversion was observed at all dose levels after one administration, with a further increase in titers after a second administration.
In non-human primates, three dose levels were assessed at 15, 45 and 135 µg per dose using a two-administration vaccination schedule, three weeks apart. Following the first administration, the majority of primates developed neutralizing antibodies reactive to the spike protein. After a second administration, 100% of non-human primates reached levels significantly higher than those from human convalescent sera by day 35.
Additionally, MRT5500-immunized mice and non-human primates both exhibited a Th1-biased T cell response against SARS-CoV-2, according to a news release.
“To tackle this global pandemic, we must look to both the strong knowledge we have from years of infectious disease expertise and the promise of new, innovative technologies,” Sanofi executive VP & global head Thomas Triomphe said in the release. “Today’s presentation of these positive results is another development milestone for providing a safe and effective potential vaccine against SARS-CoV2 and shows how promising this technology is. We are looking forward to working on next steps with our partner Translate Bio to bring this technology to people worldwide.”
“The rapid development of effective vaccines to address the COVID-19 pandemic continues to be an urgent global public health need and I am encouraged by the progress we’ve made to date with our partner Sanofi Pasteur toward the development of a promising mRNA vaccine candidate,” added Translate Bio CEO Ronald Renaud. “The preclinical results we report in this paper demonstrate the ability of MRT5500 to elicit a favorable immune response in both mice and non-human primates. Importantly, these results provide additional support for using our mRNA platform to potentially expedite the development of alternative approaches to traditional vaccines.”