Pharma BD Deal Intelligence
The deal traded a fading passive-immunization product for a hidden royalty jackpot: Sobi paid $1.5B upfront for Synagis US rights plus nirsevimab profit-share, and while Synagis was discontinued in 2025, the restructured Beyfortus royalty (25-35% of US net sales) is now delivering SEK 1.2B+ per quarter and growing through the 2030s.
The Synagis asset itself faded and was discontinued by 2025, but the bundled nirsevimab (Beyfortus) royalty right turned out to be the deal's true value driver, generating a fast-growing, high-margin US royalty stream through the 2030s.
Full analysis, sources & comparables →AstraZeneca's largest divestiture in five years; Jefferies (Sobi advisor) pegs total deal value at $2.3B once Synagis sales milestones, BLA submission payment…
Sobi confirmed it would discontinue Synagis in the US following Beyfortus's broad-label approval — the original franchise BMS Sobi acquired is now obsolete,…
Sobi FY2025: Synagis revenue collapsed (~SEK 89M for season vs SEK 520M a year earlier in Q1 alone) ahead of the Dec 31, 2025 US withdrawal, while the…
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Sobi acquired US rights to AstraZeneca's RSV antibody Synagis (palivizumab) plus a US profit share on the next-gen MEDI8897 (nirsevimab) in November 2018 for $1.5B upfront ($1.0B cash + $500M Sobi shares to AstraZeneca), plus up to $470M in Synagis sales milestones from 2026, $175M for MEDI8897 BLA submission, ~$110M in MEDI8897 profit/development milestones, and $20M/yr 2019-2021 (total deal value up to ~$2.3B). AstraZeneca's largest divestiture in 5 years. Post-close, the structure evolved as anticipated: in April 2023, ahead of the Beyfortus (nirsevimab) FDA approval, Sobi restructured the arrangement — converting its US nirsevimab profit share into a tiered royalty (25% at launch, rising 2025-2028 to 30-35% of US net sales), paying Sanofi $66M for prior R&D and terminating the AstraZeneca participation agreement for $15M. Beyfortus's July 2023 broad-label approval and Merck's clesrovimab (Enflonsia, 2025) then displaced palivizumab, and Sobi withdrew Synagis from the US market effective December 31, 2025 (FY2025 Synagis revenue had collapsed to ~SEK 89M while the Beyfortus royalty contributed ~SEK 849M), validating AstraZeneca's exit timing while leaving Sobi the durable nirsevimab royalty tail.
The Synagis asset itself faded and was discontinued by 2025, but the bundled nirsevimab (Beyfortus) royalty right turned out to be the deal's true value driver, generating a fast-growing, high-margin US royalty stream through the 2030s.
Assessment window: 5yr post-close.
70K US cases/yr
Respiratory syncytial virus is the leading cause of lower respiratory tract infection in US infants, causing 58,000-80,000 hospitalizations and 100-300 deaths annually in children under five. Premature infants and those with congenital heart or chronic lung disease face the highest risk, and until 2023 the only approved prophylaxis was monthly Synagis (palivizumab) injections during RSV season.
At the time of the 2018 Sobi-AstraZeneca transaction, Synagis (palivizumab) was the sole approved monoclonal antibody for RSV prophylaxis in high-risk infants, generating roughly $250-300M in US sales but constrained to a narrow AAP-recommended population requiring five monthly injections. AstraZeneca was already developing the next-generation MEDI8897 (nirsevimab, later Beyfortus) — a single-dose YTE-modified antibody — in partnership with Sanofi, threatening Synagis's franchise. The Sobi deal effectively monetized a declining asset before generic biosimilar pressure and Beyfortus launch, while preserving upside through a US profit share on nirsevimab. Beyfortus subsequently received FDA approval in July 2023 for all infants entering their first RSV season — a far broader label than Synagis — and CDC's 2024-25 surveillance showed 77% effectiveness against hospitalization and 80% against ICU admission. Sobi discontinued Synagis in 2024 as Beyfortus and Pfizer's Abrysvo maternal vaccine displaced it. The deal structure proved prescient: AstraZeneca captured $1.5B upfront before the franchise eroded, while Sobi monetized the tail and gained nirsevimab profit share economics.
Ahead of Beyfortus's FDA approval, Sobi converted its US nirsevimab profit share (from the 2018 AstraZeneca deal) into a tiered royalty — 25% at launch, rising 2025-2028 to 30-35% of US net sales — paying Sanofi $66M for prior R&D and terminating the AstraZeneca participation agreement for $15M. The contingent nirsevimab upside from the 2018 deal was converted into a cleaner, durable royalty stream.
Sobi confirmed Synagis (palivizumab) would no longer be available in the US as of December 31, 2025, following the broad-label Beyfortus (nirsevimab, 2023) and Merck's clesrovimab (Enflonsia, 2025) single-dose antibodies and AAP de-recommendation of routine palivizumab use. The Synagis franchise Sobi bought in 2018 reached end-of-life — validating AstraZeneca's exit timing.
Sobi's FY2025 report showed Synagis revenue effectively gone (~SEK 89M for the season) ahead of the Dec-2025 withdrawal, while the Beyfortus (nirsevimab) royalty contributed ~SEK 849M (down from SEK 1,207M; RSV season 2024/25 ~SEK 2,874M). The lasting value of the 2018 deal for Sobi is the nirsevimab royalty, not the divested Synagis product.
| Deal | Year | Value | Outcome |
|---|---|---|---|
| Swedish Orphan Biovitrum AB / AstraZeneca PLC (Synagis US rights) (this deal) | 2018 | $2.3B | 80 |
| Swedish Orphan Biovitrum AB / Biovitrum | 2001 | $493M | 84 |
| Swedish Orphan Biovitrum AB / Innate Pharma SA | 2026 | $580M | 68 |
| Swedish Orphan Biovitrum AB / CTI BioPharma Corp. | 2023 | $1.7B | 60 |
| Swedish Orphan Biovitrum AB / Arthrosi Therapeutics, Inc. | 2025 | $1.5B | — |
| Swedish Orphan Biovitrum AB / Apellis Pharmaceuticals, Inc. | 2020 | $1.0B | — |
| Vertex Pharmaceuticals Incorporated / Concert Pharmaceuticals, Inc. | 2017 | $250M | 85 |
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More: 2018 deals · Swedish Orphan Biovitrum AB deals · Respiratory deals