Biogen partners with City Therapeutics in $46 million RNAi collaboration targeting CNS disorders
Biotechnology giant Biogen has entered into a strategic research partnership with privately held City Therapeutics to develop novel RNA interference-based therapeutics for central nervous system diseases, combining next-generation RNAi engineering with proprietary drug delivery technologies.
The collaboration will leverage City Therapeutics’ advanced RNAi engineering platform alongside Biogen’s drug delivery capabilities and clinical development expertise. The partnership initially focuses on a single target mediating key central nervous system diseases, utilising tissue-enhanced delivery technologies designed to enable systemic administration of RNAi therapeutics.
Financial structure and development responsibilities
Under the agreement terms, City Therapeutics will receive $46 million in total payments, comprising a $16 million upfront payment and a $30 million investment through a convertible note representing a minority equity interest if converted. Biogen will record the upfront payment as an Acquired In-Procss Research and Development expense in the second quarter of 2025.
The collaboration includes substantial milestone potential, with City Therapeutics eligible for up to approximately $1 billion in development and commercial milestone payments, plus tiered royalties ranging from high single-digit to low double-digit percentages based on net sales. Biogen retains the option to select one additional target, subject to additional payment and target availability.
Strategic rationale and technological approach
“This collaboration underscores Biogen’s new strategic research approach of balancing our differentiated internal capabilities with external investments in cutting-edge science,” said Jane Grogan, Head of Research at Biogen. “With this effort, we are further expanding the modalities in our R&D toolbox to potentially reach our targets of interest more precisely by adding an RNAi-based approach.”
City Therapeutics will develop RNAi trigger molecules combined with Biogen’s proprietary drug delivery technology, whilst Biogen assumes responsibility for IND-enabling studies, global clinical development, regulatory submissions, and commercialisation activities.
Company backgrounds and market position
Andy Orth, Chief Executive Officer of City Therapeutics, emphasised the partnership’s significance: “Partnering with Biogen represents a meaningful milestone in our mission to expand the therapeutic reach of RNAi, as we pioneer the next generation of RNAi technology for breakthrough medicines.”
City Therapeutics, based in Cambridge, Massachusetts, has previously raised $135 million from leading life sciences investors and focuses on engineering RNAi trigger molecules to improve and expand RNAi-based medicine applications across multiple therapeutic areas.
The collaboration represents Biogen’s continued strategy of combining internal capabilities with external partnerships to advance innovative treatment modalities for neurological conditions.
