Early Positive Data for Pfizer’s mRNA COVID-19 Vaccine Candidate

Pfizer and BioNTech recently shared early Phase 1 safety and immunogenicity data from the ongoing US study of their mRNA COVID-19 vaccine candidate, BNT162b2, which has advanced into Phase 2/3 evaluation.

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Researchers found that seven days after a second 30 microgram dose ofBNT162b2  elicited SARS-CoV-2 neutralizing geometric mean titers (GMTs) in younger adults that were 3.8 times the GTM of 38 sera of SARS-CoV-2 convalescent patients and 1.6 times the GMT of the same panel.

This proved that BNT162b2 was well tolerated among all younger and older patients.

Additionally,fewer than 20 percent of the participants suffered from a mild to moderate fever reaction.

The additional Phase 1 data informed the companies’ decision to advance a 2-dose regimen of the 30 microgram dose level of BNT162b2, as announced at the end of July.

“The totality of the clinical and preclinical data informed Pfizer and BioNTech’s decision to select BNT162b2 as the lead candidate to advance into pivotal trials. We are proud to share our findings with the scientific community as we continue our work to deliver a safe and effective vaccine to combat this devastating virus,” Kathrin U. Jansen, PhD, senior vice president and head of vaccine research & development at Pfizer, said in the announcement.

“We are especially pleased to offer these early data showing our vaccine candidate’s promising safety and immunogenicity profile from the U.S. trial and we look forward to sharing T cell immune response data from the German trial in the near future.”

Previously, BNT162b displayed favorable “breadth of epitopes,” recognized in T cell responses specific to a SARS-CoV-2 spike antigen compared to the BNT162b1 candidate.

“BNT162b2 demonstrated concurrent induction of high magnitude CD4+ and CD8+ T cell responses against the receptor binding domain and against the remainder of the spike glycoprotein that is not contained in the BNT162b1 vaccine candidate,” a Pfizer spokesperson explained at the time.

T cell immune responses elicited by the vaccine candidate are currently being evaluated in the Phase 1 Germany study as well.

The additional data from the ongoing US Phase 1 study will be used to evaluate the safety and immunogenicity of varying dose levels of BNT162b1 and BNT162b2 in 195 participants.

The participants were randomized into 13 groups of 15 participants. Twelve received the vaccine and three received the placebo. The dosage level was 10 micrograms, 20 micrograms, or 30 micrograms dose levels of BNT162b1 or BNT162b2 on a 2-dose schedule, Pfizer said.

BNT162b and BNT162b2 uncovered a similar dose-dependent SARS-CoV-2- neutralizing antibody GMTs that were significantly increased after the second dose.

Both vaccine candidates evoked lower antigen-binding immunoglobulin G and neutralizing responses in older adults compared to younger adults.

But the neutralizing antibody GMTs after Dose 2 of 30 micrograms of BNT162b1 or BNT162b2 in participants 65 to 85 years old were comparable to or higher than the GMT of a panel of convalescent sera from patients aged 18 to 83 years of age, Pfizer said.

Overall, minimal adverse reactions, such as fever, fatigue, headache, chills, muscle pain, and joint pain, were more frequent in the BNT162b1 group than the BNT162b2 group.

Older BNT162b2 recipients did not report severe events and there were no reports of Grade 4 systemic events by any BNT162 recipient.

The positive data uncovered from the study led Pfizer and BioNTech to roll out the global Phase 2/3 safety and efficiency portion of the clinical study to evaluate BNT162b2 against COVID-19.

The study will enroll nearly 30,000 participants between 18 and 85 years of age.

“It is important to us to continue sharing data and related information on our COVID-19 vaccine lead candidate,” said Ugur Sahin, MD, CEO and co-founder of BioNTech.

“The favorable safety profile of BNT162b2 and the breadth of T cell responses we previously announced have supported our decision to select this candidate for the pivotal Phase 2/3 study. As of today, we have already dosed more than 11,000 participants with BNT162b2 in that study.”