Sanofi, AZ's blockbuster hopeful RSV med nears first approval as showdown with Pfizer, GSK looms

Racing against Pfizer and GSK in respiratory syncytial virus (RSV), AstraZeneca and Sanofi have cleared a key hurdle on the path to approval for their potential blockbuster nirsevimab. Still, the single-dose antibody—which will sport the brand name Beyfortus—has much to prove amid the prospect of oncoming competition.

Friday, the European Medicines Agency’s human medicines committee, CHMP, vouched for approval of Beyfortus. The drug is in the running to prevent RSV lower respiratory tract disease in newborns and infants during their first RSV season and—if approved—would become the first single-dose passive immunization for the broad infant population. That includes babies born healthy, at term or preterm, or with specific health conditions, AstraZeneca and Sanofi said.

After the CHMP endorsement, it's widely expected the European Commission will sign off on final approval. 

Stateside, a Sanofi spokesperson recently told Fierce Pharma a U.S. regulatory submission is planned for the “second half of 2022.” The French drugmaker also aims to roll out an RSV disease awareness consumer campaign in the U.S. timed to RSV awareness month in October.

Beyfortus could eventually reap peak sales of $3 billion, Jefferies analysts have predicted. Evaluate Vantage, for its part, recently cited a consensus forecast of $700 million in 2026.

While the drug will likely score approvals, commercial uptake remains an open question because the drug didn't meet its secondary endpoint of reducing RSV-related hospitalizations versus placebo in a phase 2/3 trial, Evaluate Vantage notes

Meanwhile, RSV looks poised to become a hotly contested field over the next several years.  

Aside from Pfizer and GSK, the RSV development landscape is further crowded by efforts from the likes of Novavax, Merck & Co. and Regeneron, Sanofi pointed out in an investor presentation on nirsevimab.

Pfizer, leading the RSV vaccine race, recently posted positive data on its shot prospect RSVpreF in adults ages 60 years and older. The company plans to file for approval in that population this fall. In a more direct challenge to AZ and Sanofi’s antibody, Pfizer is also testing its vaccine candidate in pregnant women to help protect their babies from RSV after birth.

GSK also chalked up a win for its vaccine candidate RSVPreF3 in older adults back in June, but on the childhood protection front, the company recently had to pause phase 3 studies over safety concerns.

Back to Beyfortus, CHMP’s blessing was based on data from the antibody’s clinical program, which found the drug led to a statistically significant reduction in occurrence of medically attended lower respiratory tract infections caused by RSV compared to placebo. In June, Sanofi and AZ unveiled results from a phase 2/3 safety and tolerability assessment that showed the med performed on par with AZ’s RSV incumbent Synagis.

Synagis, also known as palivizumab, was first approved in 1998. AstraZeneca acquired the drug in its $15.6 billion MedImmune takeover back in 2007. Synagis is currently the only drug cleared in Europe to offer passive protection against RSV, Pharmaphorum reports. Synagis is administered monthly during the five-month RSV season, whereas a single dose of Beyfortus could provide protection throughout the stretch, presenting a large convenience edge for the new med.

Once a blockbuster, Synagis brought home $410 million for AstraZenca in 2021.

RSV is the most common cause of lower respiratory tract infections in infants, as well as a leading cause of infant hospitalizations, Sanofi and AZ said. Worldwide, there were an estimated 33 million cases of acute lower respiratory infection in 2019, leading to more than 3 million hospitalizations.

With multiple drugmakers’ products in the running, the RSV market is set to undergo “significant growth” this decade, analytics firm GlobalData says.