Tweaked COVID-19 Vaccine Starts Phase II for GSK, Sanofi

GSK Sanofi_STR/NurPhoto via Getty Images

STR/NurPhoto via Getty Images

The retooled COVID-19 vaccine promised by GlaxoSmithKline and vaccine giant Sanofi is entering Phase IIb testing, with new antigen dosages it hopes will boost the lackluster immune response seen in adults 50 and over during its last Phase I/II trial.

Even if successful, the new recombinant-protein vaccine wouldn’t be available until at least the end of 2021.

Data released by the companies in December 2020 showed sufficient immune response for adults aged 18 to 49, comparable to patients who had recovered from COVID-19, and blamed the insufficient immune response seen in older patients on the concentration of antigen in the vaccine. The results forced the companies to scrap a planned Phase III trial.

The companies aim to recruit 720 adults–half over the age of 59–for the new trial at three sites in the United States, Honduras, and Panama. Patients will receive two injections spaced 21 days apart, with one of three antigen doses and a fixed adjuvant dose.

If the new formulations prove efficacious, the dosage data will help inform protocols for Phase III testing planned for the spring, putting the companies on track for a 3Q regulatory submission and a 4Q potential approval. Sanofi is also developing vaccines against new SARS-CoV-2 variants that will inform future stages of the vaccine program.

Although based on proven technology–both Sanofi’s recombinant protein technology and GSK’s pandemic adjuvant have previously been used in approved influenza vaccines–the companies’ approach has now been lapped by mRNA-based vaccines from Moderna and Pfizer-BioNTech, which both snagged emergency use authorizations in the U.S. last year. It has also fallen behind two adenovirus-based programs: AstraZeneca-University of Oxford’s vaccine was authorized in Europe last month, and Johnson & Johnsons’s could be approved this spring. And a recombinant nanoparticle-based vaccine from Novavax also announced positive Phase III data last month.

“The world needs multiple vaccines,” said Roger Connor, President of GSK Vaccines, “and we are confident that combining our proven pandemic adjuvant system with this improved antigen formulation will have significant potential as the pandemic evolves.”

The trial is supported by the Biomedical Advanced Research and Development Authority (BARDA) through the U.S.’s Operation Warp Speed, which signed a $2.1 billion contract for 100 million doses of the vaccine last year. The company also committed 300 million doses to the European Union and 72 million doses to Canada, and 60 million doses to the U.K. last year.

Sanofi is also co-developing an mRNA vaccine for COVID-19 with Translate Bio, which is on pace to begin testing in humans this quarter. Meanwhile, GSK and Vir Biotechnology launched Phase III trials last year for VIR-7831, a monoclonal antibody therapy for hospitalized adult COVID-19 patients.

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