Pharma BD Deal Intelligence
Ipsen's up to $1.31B Clementia buy for palovarotene hit trouble fast: FDA placed the FOP drug on partial clinical hold for premature growth plate closure, the MO-Ped trial was terminated, and the CVR-anchored multiple osteochondromas indication was abandoned—though palovarotene did eventually win approval as Sohonos for FOP.
Outcome grade pending — assessed 5 years post-close.
Full analysis, sources & comparables →Jefferies said the '$1.0 billion upfront acquisition of Clementia should be well received,' but the piece flagged a failed midphase study raising efficacy…
FDA placed palovarotene on partial clinical hold in pediatric FOP patients citing premature growth plate closure, an early setback to Ipsen's $1.04B Clementia…
Four years and multiple regulatory setbacks after the $1.3B Clementia deal, palovarotene finally won FDA approval as Sohonos for FOP — though the MO indication…
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Ipsen agreed to acquire Clementia for up to $1.31B, comprising $1.04B upfront ($25/share) plus a CVR of $6/share (~$263M) tied to acceptance of palovarotene NDA filing. Adds rare bone disease assets including palovarotene for fibrodysplasia ossificans progressiva and multiple osteochondromas.
Assessment window: 5yr post-close.
Fibrodysplasia ossificans progressiva is an ultra-rare genetic disorder caused by an ACVR1/ALK2 mutation that drives heterotopic ossification — the progressive formation of bone in muscles, tendons, and connective tissues following injury or inflammation. Patients become progressively immobilized as a second skeleton encases joints, with cumulative loss of function and shortened life expectancy. There is no approved disease-modifying therapy at the time of the deal.
FOP had no approved disease-modifying therapy when Ipsen acquired Clementia in 2019 — supportive care and corticosteroids for acute flare-ups defined the standard. Palovarotene, a selective RARgamma agonist designed to suppress aberrant BMP signaling and prevent heterotopic ossification, was the most advanced asset globally and the basis for Ipsen's $1.04B upfront ($25/share) plus $263M CVR ($6/share tied to MO NDA acceptance). Competing programs included Regeneron's garetosmab (anti-activin A monoclonal antibody, Phase 2 LUMINA-1) and Blueprint Medicines' BLU-782/IPN60130 (which Ipsen later in-licensed itself). Jefferies analysts flagged downside risk early, projecting peak sales could collapse from $1.85B to $270M if MO failed and chronic FOP dosing was restricted to older patients. Their concern proved prescient: palovarotene faced two FDA clinical holds, an EMA negative opinion, and an FDA CRL before finally winning US approval as Sohonos in August 2023, with the EU approval delayed and the MO indication ultimately discontinued, voiding the CVR.
The $6.00/share contingent value right (~$263M) from Ipsen's 2019 Clementia acquisition was conditioned on FDA acceptance of a palovarotene NDA for multiple osteochondromas (MO) by December 31, 2024. Ipsen terminated the MO-Ped trial in March 2020 and deemed an MO NDA 'highly unlikely'; no MO NDA was filed, so the CVR lapsed. Realized acquisition cost was the ~$1.04B upfront, not the $1.31B headline.
| Deal | Year | Value | Outcome |
|---|---|---|---|
| Ipsen S.A. / Clementia Pharmaceuticals Inc. (this deal) | 2019 | $1.3B | — |
| Ipsen S.A. / Exelixis Inc. | 2016 | $855M | 80 |
| Ipsen S.A. / Kartos Therapeutics, Inc. | 2026 | $1.8B | 68 |
| Ipsen S.A. / Memo Therapeutics AG | 2026 | $797M | 66 |
| Ipsen S.A. / Marengo Therapeutics, Inc. | 2024 | $1.2B | — |
| Ipsen S.A. / GENFIT | 2021 | $543M | — |
| Ipsen S.A. / Simcere Zaiming Pharmaceutical Co., Ltd. | 2025 | $1.1B | — |
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