AstraZeneca Eyes $10B Rhythm Pharmaceuticals Acquisition to Expand Rare Disease Portfolio

AstraZeneca has reportedly submitted a non-binding offer valued at approximately $10 billion to acquire Rhythm Pharmaceuticals, a biotechnology company developing treatments for rare genetic obesity and metabolic disorders. The proposed transaction could strengthen AstraZeneca’s rare disease portfolio while expanding its presence in specialized obesity therapeutics.

According to people familiar with the discussions, the proposal values Rhythm at up to $134 per share, including additional payments tied to the achievement of certain milestones. The Wall Street Journal previously reported that AstraZeneca had made an offer of $124 per share last month.

News of the potential acquisition sent Rhythm shares up 28% to close at $110.68, giving the company a market capitalization of approximately $7.64 billion. AstraZeneca declined to comment on the reported proposal, while Rhythm did not respond to requests for comment.

The acquisition would reportedly be pursued through Alexion, AstraZeneca’s rare disease division. The pharmaceutical company acquired Alexion in 2021 in a $39 billion transaction as part of a broader strategy to expand its specialty medicines business beyond its established oncology and biopharmaceutical operations.

Rhythm’s portfolio is focused on rare neuroendocrine and metabolic conditions, including genetic forms of severe obesity. Its lead commercial product, Imcivree (setmelanotide), received expanded FDA approval in March for the treatment of acquired hypothalamic obesity, a rare condition associated with damage to the hypothalamus. The approval marked the first US treatment specifically authorized for this form of obesity.

Adding Imcivree would give AstraZeneca access to a specialized segment of the obesity market that differs from the broader weight-management category dominated by GLP-1-based therapies from companies such as Novo Nordisk and Eli Lilly. Rather than targeting general weight loss, Rhythm’s approach focuses on underlying genetic and biological pathways involved in appetite regulation and energy balance.

Beyond its marketed therapy, Rhythm is advancing additional candidates for rare neuroendocrine and metabolic disorders, potentially providing AstraZeneca with opportunities to expand its rare disease pipeline.

The reported interest also comes amid growing pharmaceutical investment in obesity treatments. Industry forecasts suggest the global obesity drug market could exceed $100 billion in annual sales over the next decade, driven by expanding patient demand and continued development of new therapeutic approaches.

For AstraZeneca, a potential Rhythm acquisition would represent an opportunity to build on Alexion’s rare disease expertise while adding a commercial product and development pipeline targeting underserved patient populations.

The proposed transaction remains non-binding, and neither company has publicly confirmed an agreement. Financial and transaction details therefore remain subject to further developments.

For more information, visit www.astrazeneca.com.