US major Pfizer Inc. (NYSE: PFE) has agreed with China-based LianBio (OTCMKTS: LIANY) to exercise an option to take development and commercialization rights to sisunatovir, a respiratory syncytial virus (RSV) therapeutic candidate, in the territories of mainland China, Hong Kong, Macau, and Singapore. The deal is signed under an earlier strategic collaboration between the two focused on expanding patient access to novel therapeutics in Greater China.
Deal Terms and Financials
Under the terms of Pfizer’s opt-in to the sisunatovir rights, LianBio will receive a USD 20 million upfront payment, to be released from previously restricted cash paid by Pfizer to LianBio in 2020 under their existing collaboration. Additionally, LianBio is eligible to receive up to USD 135 million in potential development and commercial milestone payments and tiered low single-digit royalties on sisunatovir net sales in the territories. Pfizer will assume all development and commercial activities and costs in the region, and will release LianBio from its royalty and milestone obligations for sisunatovir.
Drug Profile and Development
Sisunatovir is an investigational orally administered fusion inhibitor designed to block RSV replication by inhibiting F-mediated fusion with the host cell. It has been granted Fast Track designation status by the US FDA. In 2020, LianBio and Pfizer entered into a collaboration aimed at developing and commercializing transformative pharmaceutical products in Greater China leveraging both LianBio’s and Pfizer’s clinical development, regulatory and commercial expertise. Under the terms of the collaboration, Pfizer will contribute up to USD 70 million of non-dilutive capital toward in-licensing, development, and commercialization. At LianBio’s discretion, products would be presented to Pfizer, and Pfizer allowed to take up development and commercial rights. The first program under development as part of that deal is sisunatovir. In June 2022, Pfizer acquired ReViral Ltd and its portfolio of RSV therapeutic candidates, with the exception of development and commercialization rights to sisunatovir in Mainland China, Hong Kong, Macau, and Singapore, which LianBio had previously in-licensed from ReViral in March 2021.
Clinical Progress and Future Prospects
Sisunatovir was shown to significantly reduce viral load in a Phase II RSV human challenge study in healthy adults and is currently being evaluated in a global Phase II clinical study in children. This strategic move positions Pfizer and LianBio to further advance the development of sisunatovir, addressing significant unmet medical needs in RSV treatment and improving patient outcomes.-Fineline Info & Tech
