Regeneron Sues Sanofi Over Dupixent Collaboration Transparency

Regeneron Pharmaceuticals has filed a lawsuit against its long-time partner Sanofi, alleging breaches in their collaboration agreement for the blockbuster drug Dupixent. The legal action, disclosed in Regeneron's recent SEC filing, centers on claims that Sanofi has withheld crucial commercial information, particularly regarding agreements with pharmacy benefit managers (PBMs) and payers.

Dispute Over Information Sharing

According to the lawsuit, Sanofi has allegedly stonewalled Regeneron's requests for full access to PBM agreements, which include details on discounts and rebates that determine Dupixent's final pricing. Regeneron argues that this lack of transparency violates their collaboration agreement and impedes its ability to make informed decisions about the drug's commercialization.

"Because Regeneron and Defendants split Dupixent's profits in the United States, Regeneron effectively pays for half of these rebates and discounts," the suit states. The company claims that without access to these agreements, it cannot verify whether Dupixent is being fairly represented in Sanofi's negotiations with payers.

Sanofi, for its part, maintains that it has not violated the terms of their partnership. A spokesperson for the French pharmaceutical giant stated, "We are in full compliance with the terms of our collaboration agreement with Regeneron. We remain focused on our shared priority with Regeneron—ensuring we continue to support the community of patients and caregivers who rely on Dupixent to treat their immunological conditions."

Dupixent's Growing Significance

The legal dispute comes at a time when Dupixent has emerged as a critical asset for both companies. In 2024, the drug became Regeneron's top-selling product, generating more than $14.1 billion in sales—a 22% increase from the previous year. Sanofi reported that Dupixent's fourth-quarter sales grew 16% to 3.5 billion euros ($3.6 billion), surpassing its annual sales target of 13 billion euros.

Dupixent, a humanized IgG4 monoclonal antibody that blocks IL-4 and IL-13 signaling, is approved for multiple indications including atopic dermatitis, asthma, chronic rhinosinusitis with nasal polyps, eosinophilic esophagitis, and most recently, chronic obstructive pulmonary disease (COPD). Some analysts project that the drug could reach $20 billion in peak sales following its recent COPD approval.

Historical Context and Future Implications

The Regeneron-Sanofi collaboration on Dupixent dates back to 2007 when Sanofi paid $85 million upfront and committed up to $475 million in research funding. This long-standing partnership has been crucial in developing and commercializing Dupixent, with both companies sharing development costs and profits.

As the lawsuit unfolds, the pharmaceutical industry will be watching closely to see how this dispute affects not only the Dupixent collaboration but also sets precedents for transparency in similar partnerships. The outcome could have significant implications for how pharmaceutical companies structure and manage their collaborations in the future, particularly regarding the sharing of sensitive commercial information.