Sanofi, GSK Halt Adjuvanted COVID-19 Vaccine Program

Sanofi and GSK recently announced they will  delay a program testing an adjuvanted COVID-19 vaccine after results from a Phase 1/2 study showed a low immune response in older adults.

The companies stated that while the immune response is comparable to patients 18 to 49 years old who recovered from COVID-19, the low immune response in older adults is likely due to an insufficient concentration of the COVID-19 antigen. 

“We care greatly about public health which is why we are disappointed by the delay announced today, but all our decisions are and will always be driven by science and data. We have identified the path forward and remain confident and committed to bringing a safe and efficacious COVID-19 vaccine,” Thomas Triomphe, executive vice president and head of Sanofi Pasteur, said in the announcement.

“Following these results and the latest encouraging new preclinical data, we will now work to further optimize our candidate to achieve this goal. No single pharma company can make it alone; the world needs more than one vaccine to fight the pandemic,” Triomphe continued.

A previous study found that the vaccine candidate could protect against lung pathology and lead to rapid viral clearance from the nasal passage and lungs in non-human primates. 

Therefore, despite the negative outcomes in the Phase 1/2 study, Sanofi and GSK stated that they are confident that the capacity of the adjuvanted recombinant platform can deliver a highly efficient vaccine for all adults in the near future. 

“The results of the study are not as we hoped. Based on previous experience and other collaborations, we are confident that GSK’s pandemic adjuvant system, when coupled with a COVID-19 antigen, can elicit a robust immune response with an acceptable reactogenicity profile,” said Roger Connor, president of GSK.

“It is also clear that multiple vaccines will be needed to contain the pandemic. Our aim now is to work closely with our partner Sanofi to develop this vaccine, with an improved antigen formulation, for it to make a meaningful contribution to preventing COVID-19,” Connor stated.

The collaboration between Sanofi and GSK began in mid-April when the companies signed a letter of intent to develop an adjuvanted COVID-19 vaccine.

As part of the initiative, Sanofi would provide its S-protein COVID-19 antigen and GSK would provide its pandemic adjuvanted technology.

Sanofi’s recombinant technology and GSK’s pandemic adjuvant have both proven successful against influenza. Both technologies offer stability at temperatures used for routine vaccines, the ability to generate high and sustained immune responses, and the potential to prevent virus transmission, Sanofi stated. 

At the end of July, GSK announced that the US government provided nearly $2.1 billion to further develop a COVID-19 vaccine using their technology.The grant was also to be used for manufacturing and delivery of an initial 100 million doses of the vaccine.

GSK and Sanofi also made individual agreements with the UK government and the European Commission (EC) to supply 60 million and 300 million of their COVID-19 vaccine, respectively. 

The agreement with the EC will allow the purchase of the vaccine for all member states of the European Union and provide funding to support the scaling up of Sanofi and GSK manufacturing capabilities on European soil, a September announcement said. 

Sanofi and GSK expect a Phase 2b study to start in February 2021 with support from the Biomedical Advanced Research and Development Authority (BARDA). 

Specifically, the study will include a comparison with an authorized COVID-19 vaccine. If data are positive, a global Phase 3 study could start in Q2 2021. 

Positive results from this study would also lead to regulatory submissions in the second half of 2021, which would ultimately delay the vaccine’s potential availability from mid-2021 to Q4 2021.