Vaccine giants Sanofi and GSK are joining the ranks of Covid-19 vaccine makers testing their candidates in people, launching a large Phase 1/2 clinical trial Thursday that will take place at 11 sites across the United States.
The trial, which is expected to be completed by early December, would pave the way for a pivotal Phase 3 efficacy trial to start the same month, if the experimental vaccine proves to be safe, tolerable, and appears to be generating enough of an immune response to proceed.
Sanofi, which is the lead partner, intends to enroll more than 400 people in the Phase 1/2, an unusually large number for a first-in-human trial of a vaccine. In the first phase of the trial, healthy subjects 18 to 49 years of age will be vaccinated to establish the correct dose for the vaccine. Later, a broader group of participants, including at least 140 adults aged 50 and older, will be enrolled.
“We think we can move very rapidly to expansion from the very first subjects that get the vaccine,” John Shiver, Sanofi’s global head of vaccines research and development, told STAT.
While several other experimental Covid-19 vaccines are already in Phase 3 trials, this candidate is the first outside of China to use a vaccine approach for which there is already a licensed vaccine. The approach used is the same as that used for Sanofi’s Flublok vaccine.
The Sanofi vaccine is combined with an adjuvant — a compound that enhances the immune response to the vaccine — produced by GSK. Like most of the Covid-19 vaccines currently in production, it will be a two-dose vaccine.
The three candidates already in Phase 3 trials in the U.S. use vaccine platforms that have not yet produced licensed vaccines. Moderna and Pfizer use a messenger RNA approach, while a vaccine being developed by Oxford University and AstraZeneca uses a harmless adenovirus onto which genetic material from the SARS-CoV-2 virus — which causes Covid-19 — has been fused. The adenovirus, which doesn’t trigger illness, induces the immune system to generate a protective response to SARS-2.
Unlike the mRNA vaccines, which need to be transported and stored frozen, the Sanofi vaccine will be shipped in liquid form and can be stored at refrigerator temperatures, between 2 Celsius and 8 Celsius, Shiver said.
The Pfizer vaccine must be stored at -70 Celsius, which will complicate delivery and distribution.
Sanofi is also working on a second vaccine, an mRNA vaccine, which it is making in partnership with Translate Bio. Human trials with this vaccine are expected to start in November.
It is possible one or more vaccines could already be licensed or at least in use under an Emergency Use Authorization before either of Sanofi’s vaccines begins its Phase 3 trial. But Shiver seemed unfazed.
“We’re not that far behind,” he said, noting the global need for Covid-19 vaccines cannot be filled by a few vaccine manufacturers. “The threat of this virus and pandemic are large enough that the world needs multiple types of approaches for it.”