The collaboration will focus on development of MedImmune’s candidate MEDI8897 which was granted fast-track designation by the US Food and Drug Administration (FDA) in 2015.
The mAb binds RSV’s fusion protein, which is present on both the surface of the virus and infected cells. The drug is designed to have a long half-life which, according to Medimmune, means a single dose is sufficient to provide protection.
MEDI8897 is currently being tested in a Phase IIb clinical study.
Sanofi will pay MedImmune €120m ($126m) upfront. The agreement may also see the French vaccine specialist pay up to €495m based on the achievement of regulatory and sales milestones.
The firms will share development costs and any revenues generated by MEDI8897.
A Sanofi spokesman told us "MedImmune will continue to lead all development activity up to the first approval, and AstraZeneca will retain MEDI8897 manufacturing activities."
Sanofi will be responsible for commercializing the product.
MedImmune's portfolio includes the RSV treatment Synagis (palivizumab) which has been on the market since 1998.