Pfizer, BioNTech unveil data that gave partners their lead vaccine
Pfizer and BioNTech have revealed the clinical data that led the partners to choose which vaccine they would send into Phase III testing for COVID-19.
Side-by-side Phase I/II safety and immunogenicity data for the 30 µg doses of BNT162b2, the Phase III candidate and dose selected by Pfizer Inc. (NYSE:PFE) and BioNTech SE (NASDAQ:BNTX), and BNT161b1, the partners’ original lead vaccine, in volunteers aged 18-55 and 65-85 showed the former to be safer and more immunogenic. The data, which also include results for lower doses, were published Thursday in medRxiv.
Fewer volunteers given BNT162b2 compared with BNT162b1 in both groups reported local or systemic adverse events (AEs) after the second dose. In the older group, systemic AEs were mild or moderate for everyone who received BNT162b2, whereas some given BNT162b1 had severe AEs.
In both age groups, prime-boost administration of BNT162b2 led to slightly higher mean neutralizing antibody titers at day 28 than the other vaccine. Levels in elderly participants were a little under half that in the younger volunteers. The average titer in each group was higher than the average from a convalescent sera panel.
The partners began the international 30,000-volunteer Phase III trial of BNT162b2 in late July. The two have said they expect to be ready to seek FDA approval or an Emergency Use Authorization as early as October (see “Pfizer Lays Out Two Phases of COVID-19 Vaccine Pricing”).
BNT162b2 is an RNA vaccine encoding a full-length spike; BNT162b1 is an RNA subunit vaccine encoding the spike receptor-binding domain. The companies had cited similar immunogenicity but a better safety profile for BNT162b2 vs BNT161b1 when they announced the selection of the vaccine to advance into Phase III (see “BioNTech, Pfizer Vaccine Yields High Titers”; “mRNA Vaccines Enter Pivotal Testing”).
BioNTech and its partner in China and Taiwan, Shanghai Fosun Pharmaceutical Group Co. Ltd. (Shanghai:600196; HKEX:2196), began a Chinese Phase I study of BNT162b1 in early August.
On Wednesday, Novavax Inc. (NASDAQ:NVAX) showed in bioRxiv that prime-boost administration of Phase I/II doses of NVX-CoV2373 enabled cynomolgus macaques to quickly shut down SARS-CoV-2 replication. Vaccinated monkeys simultaneously infected intranasally and intratracheally had undetectable SARS-CoV-2 RNA in lung fluid and nasal samples at days two and four postchallenge; and little to no signs of lung inflammation seven days after infection.
Unvaccinated monkeys had detectable viral RNA in both sample types at days two and four, and moderate to severe lung inflammation at day 7.
Two weeks ago, Novavax presented baboon protection data alongside its Phase I/II safety and immunogenicity readout for 5 or 25 µg NVX-CoV2373 plus 50 µg of the company’s Matrix-M adjuvant. The data cumulatively suggested the biotech has room to lower the protein-based vaccine’s dose (see “Novavax COVID-19 Vaccine Potently Immunogenic with Room to Lower Dose”).
NVX-CoV2373 is in a South African Phase IIb efficacy trial and is expected to start Phase III testing in October.
Also in bioRxiv Wednesday, Elicio Therapeutics showed COVID-19 vaccine ELI-005 strongly induced antigen-specific CD8+ and CD4+ T cell responses in the spleen, peripheral blood and lungs in mice. The data showed the vaccine produced high neutralizing antibody titers in mice aged 6-8 weeks, and led to robust humoral and cellular immune responses in 37-week-old mice.
ELI-005 is a protein subunit vaccine comprising a mixture of the spike RBD with ELI-004, an adjuvant from Elicio’s Amphiphile platform. Amphiphile attaches antigens to an albumin-binding lipid tail for transport to lymph nodes, where antigen-presenting cells display antigens to activate T cells (see “Elicio Targets Cancer Vaccines to Lymph Nodes”).