AstraZeneca’s biologics R&D arm MedImmune and Sanofi’s vaccines division Sanofi Pasteur have agreed to develop and jointly commercialize the monoclonal antibody MEDI8897 for the treatment of lower respiratory tract illness (LRTI) caused by respiratory syncytial virus (RSV).

This virus is the primary cause of LRTI among infants and young children. Most infants are infected before the age of one and virtually all get an RSV infection by the age of two, according to the US Centres for Disease Control and Prevention (CDC).

Under the terms of the agreement, Sanofi Pasteur will make an upfront payment of €120 million and pay up to €495 million upon achieving certain milestones. Both companies will lead all development activity through initial approvals and share all costs and profits equally. AstraZeneca will retain manufacturing activities for MEDI8897 while Sanofi Pasteur will lead commercialization efforts.

“By combining our development expertise and leadership in RSV with Sanofi Pasteur’s significant global experience in commercializing pediatric vaccines, we hope to provide an RSV disease prevention approach for all infants, both term and pre-term,” saidMedImmune’s executive vice president, Bahija Jallal. The treatment is being developed for the passive immunization of a broad infant population.

The drug is currently undergoing Phase IIb clinical trials in pre-term infants who are not eligible for MedImmune’s other RSV treatment Synagis, the only therapy currently approved for preventing LRTI caused by RSV in children at high risk. A Phase III trial is planned in healthy full-term and late pre-term infants. MEDI8897 has received fast track designation from the US Food & Drug Administration.