Pfizer's Trumenba just got closer to a new FDA nod. Can it catch up to GlaxoSmithKline's Bexsero?

Compared to Bexsero's 2017 sales of $776 million, Trumenba was lumped into Pfizer's “all other vaccines” category, whose total sales was $266 million. (Pfizer)

Hot on the heels of men B rival GlaxoSmithKline, Pfizer's vaccine Trumenba picked up an FDA “breakthrough” designation that could speed its move toward a bigger market. And with the Pfizer shot's sales lagging behind GSK's Bexsero, Trumenba could use the lift.

Thing is, though, the breakthrough tag covers Trumenba use in children as young as 1 year of age—and that's very similar to the breakthrough designation Bexsero won just two months ago. The GSK vaccine is up for approval in kids as young as 2. Both shots are now approved for 10- to 25-year-olds.

The two vaccines won initial approvals just three months apart—October 2014 for Trumenba, January 2015 for Bexsero, then owned by Novartis—but their paths split after that. Numbers-wise, the Pfizer shot is so far behind, it hasn’t even returned enough revenue to warrant a standalone position in Pfizer’s annual report. The company still lumps Trumenba sales into its “all other vaccines” category, which together brought in $266 million last year.

By contrast, since GSK acquired Bexsero in an asset transfer with Novartis, it has become a key revenue driver for the U.K. drugmaker's vaccines business. In 2017, Bexsero sales climbed 34% at constant exchanges rate to £556 million, or about $776 million. For the first quarter, Bexsero leapt 79% year over year.

RELATED: Pfizer’s Trumenba to challenge GlaxoSmithKline's Bexsero with EU nod

Demand was so high, in fact, that GSK ran into a shortage last year; it's now investing $175 million in a German plant to ramp up supply, but that won’t start making doses until the end of 2020. (Pfizer tried to play on that GSK supply issue, saying in a Trumenba press release last year that it's “focused on consistent, reliable supply” for all its vaccines.)

Part of the sales difference between the two lies overseas, where the GSK shot has the jump on Pfizer. Trumenba just entered Europe last year, for instance, while Bexsero has been on sale there for more than four years.

But the approvals by age group could make a big difference themselves. For now, the edge would appear to lie with Trumenba and its potential “as young as 1 year” approval, compared with Bexsero's application for kids as young as 2. But 1-year-olds likely would be as young as Trumenba is likely to be able to go. In its original approval letter in 2014, the FDA nixed Trumenba's use in infants younger than 1, saying evidence "strongly" suggests the vaccine would be unsafe in that age group.

“Safety data from a clinical study in infants vaccinated with a reduced dosage formulation showed an unacceptably high incidence of fever after a single dose,” the agency said.

RELATED: Don't sweat Prevnar's problems, Pfizer R&D chief says. New vaccines are on their way

Bexsero, on the other hand, is approved in some parts of the world in infants as young as 2 months. And it's under testing for infant and toddlers under 2. The FDA's original approval letter for Bexsero called for GSK to test the shot in infants 6 weeks to 12 months, and in a separate study, infants 2.5 months to 11 months and 2 to 10 years. 

As the CDC’s 2016 Enhanced Meningococcal Disease Surveillance Report shows, infants accounted for 20% of total MenB cases in the States, compared to 32% for adolescents and young adults. Children 1 to 4 represent 12% of cases, while those who are between 5 and 10 years old make up 4%.

Still, GSK's not near an approval in infants yet. And an expansion into kids as young as 1 could be a welcome boost for Trumenba at a time when Pfizer's top-selling shot, Prevnar 13, is under sales pressure. The Big Pharma is also working on other promising vaccines programs, including one late-stage product against Clostridium difficile.