Virus World

CanSino and Moderna are the first vaccine makers to report data on safety and neutralization, but the extent of protection these products afford remains unclear.  CanSino Biologics and a team of researchers from seven different Chinese institutions have published the results of a phase 1 trial of the company’s SARS-CoV-2 spike (S) protein vaccine. The intramuscularly injected adenoviral vaccine elicited both neutralizing antibodies and a T-cell response in a phase 1 study in 108 volunteers. A week earlier, Moderna raised a cool $1.34 billion in a share offering after it press-released preliminary data from just eight healthy volunteers from a phase 1 trial of its mRNA vaccine candidate against SARS-CoV-2. The limited data released suggest that their vaccine can stimulate the production of neutralizing antibodies and appears to be safe in a tiny group of individuals; it is not clear how these relate to antibody responses in the general population.

CanSino’s open-label dose-escalation study found that 75–83% of patients in three groups, each with a different dosage (5 × 1011, 1 × 1012 or 5 × 1012 viral particles), reported at least one adverse reaction by day 7, such as pain at the injection site and sometimes fever, fatigue, headache and muscle pain. The effects were most severe at the highest dose, and the vaccine’s developers plan to take the medium dose into a phase 2 trial. Tantalizingly, the preliminary data also indicate the adenoviral serotype 5 (Ad5) vaccine generates neutralizing antibody and T-cell responses, although whether the reported responses will prove to be protective is open to question. “We have no idea what titers are needed to protect,” says Hildegund Ertl, professor in the Wistar Institute’s Vaccine & Immunotherapy Center. The lack of a standardized virus neutralization assay for SARS-CoV-2 complicates data interpretation. “As long as people are using different assays, it’s going to be hard to figure that out.”

But just 50% of those who received the medium dose developed neutralizing antibodies, a rate that, Ertl says, “is not particularly good.” The T-cell response was “not particularly impressive” either...

Among a long list of biopharma companies developing vaccines against the novel coronavirus, China’s CanSino Biologics and Massachusetts-based Moderna Therapeutics are so far the front-runners. After Moderna dosed its first subject this week, CanSino said it's been cleared to start its trials. CanSino Bio and its collaborators at the Academy of Military Medical Sciences’ Institute of Biotechnology secured a quick Chinese regulatory go-ahead to start human testing of their recombinant coronavirus vaccine, the company said in a disclosure (PDF) to the Hong Kong Stock Exchange on Wednesday. “Thanks to our collaborators and our diligent team, who worked almost around the clock since late January to develop this vaccine candidate with sound scientific data to support IND filing,” CanSino Chairman and CEO Xuefeng Yu said in a statement.

The green light was doled out very quickly. It was only Tuesday when CanSino said it had filed the pre-IND review application for the vaccine to authorities and was in the process of a rolling submission of technical documents. CanSino’s candidate, dubbed Ad5-nCoV, uses its adenovirus-based viral vector vaccine platform. In 2017, the same technology helped the company earn a Chinese nod for its Ebola vaccine, which was the first Ebola shot approved anywhere based on the strain behind the deadly epidemic in West Africa in 2014. The new phase 1 trial will be conducted in healthy adults 18 to 60 years of age in Wuhan, China, which was first to report cases of the current SARS-CoV-2 virus. Investigators plan to divide 108 participants into three groups to receive different doses of the vaccine, according to information posted on the Chinese Clinical Trial Registry. While the study’s main objective is to examine the vaccine’s safety, researchers will also evaluate efficacy measures, including levels of an antibody against the spike protein on the coronavirus cell surface that’s key for infection, as well as neutralizing antibody against SARS-CoV-2.