Fewer than five months after rejecting a takeover approach by Biogen, Sage Therapeutics has found a buyer in Supernus Pharmaceuticals.
According to the deal, Supernus will pay up to $795m to acquire depression treatment specialist Sage. The contract value significantly eclipses the $469m offered by Biogen in January 2025, a proposal that was swiftly rejected by Sage.
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The transaction has been approved by the boards of directors of both US-headquartered companies and is expected to close in Q3 2025.
Share price in Sage surged 26% at market open in the US following the announcement on 16 June while Supernus shares opened 1% higher.
In a statement, the two biotechs said that Sage is a “strong fit with existing Supernus infrastructure”. Supernus has approved products in the US to treat Parkinson’s disease and attention deficit hyperactivity disorder (ADHD), among others.
Supernus is acquiring all shares of Sage for a price of $8.50 each, totalling an initial $561m. An additional $3.50 per share will be added to the deal depending on sales and commercial milestones for Sage’s flagship product Zurzuvae (zuranolone), giving a potential deal value of $795m.
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By GlobalDataZurzuvae, whose ownership rights will now transfer to Supernus, is the only US Food and Drug Administration (FDA)-approved pill to treat postpartum depression. The acquisition affords Supernus a dominant position in the market.
Co-developed with Biogen, Zurzuvae earned Sage $36.1m in sales in 2024 and $13.8m in Q1 2025.
Following a 2020 agreement, Biogen has the exclusive licence to develop and commercialise Zurzuvae outside the US, excluding Japan, Taiwan, and South Korea. Sage, and now Supernus, retains US rights.
Analysis by Pharmaceutical Technology‘s parent company GlobalData forecasts US sales of the drug to reach $290m by 2031.
Sage struggled late last year with a series of mid-stage clinical trial failures. The company laid off 55% of its R&D team as a result, prioritising the commercial launch of Zurzuvae instead.
Supernus’s CEO Jack Khattar said: “[The acquisition] augments our growth profile by adding a significant fourth growth product to our portfolio and further diversifies our sources of future growth. Zurzuvae aligns with our focus on acquiring novel value-enhancing and clinically differentiated medicines to treat central nervous system conditions.”
“We have a proven track record of strong commercial execution, and we look forward to building on Zurzuvae’s US growth momentum and collaboration with Biogen, so that more women with postpartum depression can benefit from this novel treatment.”
