Sanofi pays €120M to buy into AstraZeneca RSV program

Sanofi Pasteur
Sanofi will lead commercialization of AstraZeneca's MEDI8897 if it wins approval.

Sanofi has paid €120 million ($126 million) upfront and committed to up to €495 million more for a stake in AstraZeneca’s experimental monoclonal antibody against respiratory syncytial virus (RSV). The agreement will see Sanofi and AstraZeneca equally share costs and profits for a phase 2b asset with the potential to immunize infants against a virus that kills 160,000 children a year.

AstraZeneca’s MedImmune picked up the rights to AIMM Therapeutics’ anti-RSV mAb D25 in 2009, and went on to initiate a phase 2b study in preterm infants in the back half of last year. Now, with the start of a phase 3 study in healthy full-term infants on the horizon, AstraZeneca has brought on board a partner with deep experience of commercializing vaccines and the financial clout to share the burden of pushing MEDI8897 toward approval.

"RSV is considered to be the most important missing indication in the vaccination schedule of newborns," Sanofi EVP David Loew said in a statement. "As a global leader in the pediatric vaccine industry, this deal with MedImmune therefore makes perfect sense for Sanofi Pasteur. RSV causes major, seasonal worldwide outbreaks and the severity is predominant among young infants."

The approach taken by AstraZeneca to protecting infants against RSV relies on passive immunity. Instead of exposing the immune system to a pathogen to generate active immunity—as traditional vaccines do—MEDI8897 is designed to provide infants with a ready-made pool of mAbs that can defend the body from RSV.

Passive immunity is a well-established idea—the transfer of antibodies from mother to child is an example—but the short half life of mAbs has limited therapeutic uses. Antibodies have been used to give at-risk kids protection against RSV, but the need for monthly injections ratchets up the cost and inconvenience. And, in conjunction with the hit-and-miss efficacy of the approach, this has limited uptake.

AstraZeneca thinks its engineering of MEDI8897 has overcome these limitations. The expectation is a single dose of MEDI8897 will provide immunity for the whole RSV season. Once in the body, the mAbs are designed to bind to the RSV fusion protein found on virions and infected cells and, in doing so, neutralize the virus.

FDA was sufficiently impressed by the program to award it fast-track status in 2015. And Sanofi has now provided further validation of the asset by paying €120 million upfront and committing to up to €495 million more in milestones for a 50% stake in the program. MedImmune will head up development until the first approval and split the costs with Sanofi. If the mAb wins approval, Sanofi will lead commercialization efforts and share the profits equally with its partner. AstraZeneca will continue to handle manufacturing.

Sanofi already has an infant RSV vaccine in its pipeline. But, as a phase 1 program, that asset is lagging behind MEDI8897 in a competitive niche with a long history of failure. Novavax became the latest in a line of companies going back decades to fall short in the clinic with an RSV vaccine when it posted data from its phase 3 last year.

That blow and other setbacks have done little to deter companies from trying to crack what could be a major market. The AstraZeneca-Sanofi deal is the second RSV mAb pact of the week, coming five days after Aranis picked up a program from Adimab.