Pharma BD Deal Intelligence
Pfizer's $340M all-cash acquisition of Idun Pharmaceuticals ended in a fire sale—Pfizer divested the entire subsidiary back out for a token $250K plus a $1M note just five years later after failing to advance the lead apoptosis program. The compound, later renamed emricasan, went on to fail three separate Phase IIb trials under new ownership, confirming Pfizer's original bet never had a path to approval.
Pfizer paid ~$340M for Idun in 2005, then sold the whole subsidiary back for essentially nominal consideration ($250K + a $1M note) in 2010 after failing to advance its lead apoptosis/caspase program — the asset (emricasan) went on to fail three separate Phase IIb liver-disease trials under its new owner, Conatus, confirming the science never panned out.
Full analysis, sources & comparables →Pfizer to acquire Idun Pharmaceuticals; lead asset IDN-6556 in Phase 2 for liver transplant patients and hepatitis C with data showing it is well tolerated and…
An in-process research and development charge of $0.3 billion relating to the pending acquisition of Idun Pharmaceutical, Inc.
Conatus Pharmaceuticals reacquired Pfizer's Idun subsidiary five years post-acquisition, signaling Pfizer deprioritized the apoptosis liver-disease platform.
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Pfizer completes acquisition of Idun Pharmaceuticals (apoptosis-focused biotech). Estimated $298M (some sources $400-500M); $250M IPR&D charge.
Pfizer paid ~$340M for Idun in 2005, then sold the whole subsidiary back for essentially nominal consideration ($250K + a $1M note) in 2010 after failing to advance its lead apoptosis/caspase program — the asset (emricasan) went on to fail three separate Phase IIb liver-disease trials under its new owner, Conatus, confirming the science never panned out.
Assessment window: 15yr post-close.
Idun's apoptosis platform targeted hepatocyte cell death — a driver of liver injury in hepatitis C, transplant ischemia-reperfusion injury, and (later identified) NASH. Lead asset IDN-6556 (emricasan) was a first-in-class oral pan-caspase inhibitor that lowered ALT/AST aminotransferases in early Phase 2 hepatitis C and liver preservation studies.
In 2005, the hepatitis C standard of care was pegylated interferon plus ribavirin, with Schering-Plough (PEG-Intron) and Roche (Pegasys) dominating; cure rates ran 40–50% in genotype 1. Direct-acting antivirals were still years away (Vertex's telaprevir approved 2011; Gilead's Sovaldi 2013). Caspase inhibition was a differentiated, non-antiviral path aimed at reducing liver injury rather than viral clearance — broader applicability across liver transplant, NASH, and chronic HCV. Competitors in apoptosis modulation included Vertex (caspase-1 inhibitors for inflammation), GSK, and Maxygen platform plays. Pfizer's $250M IPR&D charge signaled it valued the platform plus IDN-6556 as a Phase 2 lead. Strategically, the deal expanded Pfizer's apoptosis IP (>150 patents) and added preclinical caspase-1 inhibitor IDN-1114 for inflammation. Pfizer ultimately deprioritized emricasan, returning it to Conatus in 2010; Conatus licensed it to Novartis (2017) for NASH cirrhosis. Emricasan failed primary endpoints in three pivotal NASH trials (ENCORE-NF, ENCORE-PH, ENCORE-LF), invalidating the standalone caspase-inhibitor thesis for advanced liver disease.
| Deal | Year | Value | Outcome |
|---|---|---|---|
| Pfizer Inc. / Idun Pharmaceuticals, Inc. (this deal) | 2005 | $298M | 10 |
| Pfizer Inc. / BioNTech SE | 2020 | $748M | 100 |
| Pfizer Inc. / FoldRx Pharmaceuticals | 2010 | — | 99 |
| Pfizer Inc. / Medivation Inc. | 2016 | $14.0B | 86 |
| Pfizer Inc. / Wyeth | 2009 | $68.0B | 86 |
| Pfizer Inc. / Warner-Lambert Company | 2000 | $90.0B | 83 |
| Pfizer Inc. / Arvinas, Inc. | 2021 | $2.4B | 77 |
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