Biogen and City Therapeutics Forge Strategic Partnership to Pioneer Next-Generation RNAi-Based Therapies Targeting Central Nervous System Diseases
Biogen,a global leader in neuroscience and neurodegenerative disease research, and City Therapeutics, Inc., a private biopharmaceutical company at the forefront of RNA interference (RNAi) technology innovation, have announced a landmark strategic research collaboration to jointly develop novel RNAi-based therapeutic candidates. This partnership marks a significant advancement in both companies’ efforts to harness the power of RNAi to address critical unmet medical needs, particularly within the central nervous system (CNS) disease space.
Expanding RNAi Therapeutics through Collaborative Innovation
The collaboration will leverage City Therapeutics’ proprietary next-generation RNAi engineering platform to design and optimize RNAi trigger molecules with enhanced specificity and efficacy. These RNAi triggers will be combined with Biogen’s proprietary and cutting-edge drug delivery technologies, which focus on improving the systemic administration and tissue-targeted delivery of therapeutics, particularly to the CNS—a notoriously challenging target for drug delivery due to the protective blood-brain barrier.
City Therapeutics’ RNAi platform utilizes advanced molecular engineering techniques to improve the stability, potency, and targeted delivery of RNAi molecules. By pairing this with Biogen’s extensive expertise in CNS biology, clinical development, and regulatory strategy, the collaboration aims to create innovative RNAi medicines that could potentially transform treatment paradigms for devastating CNS diseases.
The initial focus of this partnership will center on a specific, undisclosed molecular target known to play a pivotal role in key CNS disorders. By utilizing tissue-enhanced delivery methods, the collaboration hopes to achieve effective systemic delivery, thereby reducing the need for invasive administration methods and improving patient outcomes and convenience.
Roles and Responsibilities: A Synergistic Partnership
Under the terms of the agreement, City Therapeutics will spearhead the RNAi molecule design and optimization, leveraging its deep RNAi expertise and proprietary platform technology. Biogen will assume responsibility for conducting Investigational New Drug (IND)-enabling studies, leading global clinical development programs, preparing regulatory submissions, and driving commercialization efforts worldwide.
This division of labor capitalizes on the strengths of each company: City Therapeutics’ innovative RNAi design capabilities combined with Biogen’s vast experience in clinical trials, regulatory affairs, and market access in the neuroscience space.
Strategic Significance for Biogen
Jane Grogan, Ph.D., Head of Research at Biogen, emphasized the strategic importance of the collaboration, stating, “This partnership embodies Biogen’s evolving research strategy, which emphasizes augmenting our internal capabilities with innovative external science and technologies. RNAi represents a powerful modality for gene silencing with the potential to address targets that have been challenging to modulate with traditional therapeutic approaches. By integrating RNAi into our R&D portfolio, we are expanding our toolkit to more precisely and effectively intervene in disease pathways.”
Dr. Grogan continued, “We are thrilled to collaborate with the talented team at City Therapeutics and to invest in their pioneering platform as part of our broader commitment to discovering transformative medicines. Together, we are aiming to develop new RNAi therapies that could have meaningful impact on patients suffering from debilitating CNS conditions.”
City Therapeutics’ Vision and Growth
Andy Orth, Chief Executive Officer of City Therapeutics, reflected on the significance of the collaboration: “Joining forces with Biogen is a pivotal milestone for City Therapeutics as we continue to push the boundaries of RNAi technology. Our mission has been to advance the next generation of RNAi therapeutics by engineering molecules that can be delivered systemically and selectively engage disease-relevant tissues.”
Orth added, “By leveraging Biogen’s world-class global drug development capabilities alongside our RNAi platform, we anticipate accelerating the development of breakthrough therapies for serious diseases where there remains a substantial unmet medical need. We look forward to validating the potential of our technology through this collaboration and to delivering new therapeutic options that could improve patient lives.”
Financial and Commercial Terms
Financially, the collaboration agreement includes a $46 million total commitment from Biogen to City Therapeutics. This comprises a $16 million upfront payment to City Therapeutics and a further $30 million investment in the form of a convertible note, which may convert into equity, giving Biogen a minority ownership stake in City Therapeutics if converted.
Biogen will record the upfront payment as an Acquired In-Process Research and Development (IPR&D) expense in its second quarter financials for 2025. Additionally, City Therapeutics is eligible to receive milestone payments totaling up to approximately $1 billion, contingent upon achievement of pre-defined clinical, regulatory, and commercial milestones. These incentives underscore the high expectations placed on the RNAi programs developed through the partnership.
In addition to milestone payments, City Therapeutics may also receive tiered royalties ranging from high single digits to low double digits based on net sales, providing significant upside potential linked to the commercial success of the therapies.
Furthermore, Biogen retains the option to select an additional molecular target under the terms of the collaboration, subject to further payments and target availability, reflecting Biogen’s strategic flexibility to expand the partnership as promising opportunities arise.
RNAi Therapeutics: A Transformative Modality
RNA interference is a natural cellular process that regulates gene expression by selectively silencing messenger RNA (mRNA) molecules, thereby preventing the production of disease-causing proteins. Harnessing RNAi as a therapeutic modality allows for precise targeting of genes implicated in a wide variety of diseases, including those that have historically been difficult to address with traditional small molecules or antibodies.
Over the past decade, RNAi therapeutics have shown significant clinical potential, with several RNAi-based drugs gaining regulatory approval for rare genetic diseases and other conditions. However, the delivery of RNAi molecules, particularly to organs such as the brain and other parts of the CNS, remains a formidable challenge. This collaboration’s focus on improved tissue-targeted delivery technologies aims to overcome these hurdles, making RNAi-based therapies more broadly applicable to CNS disorders.
Implications for CNS Disease Treatment
Central nervous system diseases—including neurodegenerative disorders such as Alzheimer’s disease, Parkinson’s disease, Huntington’s disease, and other neurological conditions—represent some of the most pressing unmet medical challenges. Current treatments often provide symptomatic relief without altering disease progression.
The integration of RNAi therapeutics into Biogen’s pipeline through this collaboration holds the promise of enabling new disease-modifying approaches that could silence the genes driving pathological processes at their root. If successful, these RNAi therapies could represent a paradigm shift in CNS treatment by offering targeted, systemic, and less invasive options for patients.
The strategic collaboration between Biogen and City Therapeutics is a compelling example of how leading biotech companies are joining forces to leverage cutting-edge scientific advances for the development of innovative medicines. By combining City Therapeutics’ next-generation RNAi platform with Biogen’s clinical development expertise and drug delivery technologies, this partnership aspires to create novel RNAi-based therapies with the potential to transform treatment for debilitating central nervous system diseases.
As this collaboration progresses, it will be closely watched by the biotech and pharmaceutical industries as a beacon of how modality innovation and strategic partnerships can accelerate the development of next-generation medicines with profound patient impact.
