Pharma BD Deal Intelligence
BMS's $190M all-cash acquisition of Kosan Biosciences fizzled: the lead Hsp90 inhibitor tanespimycin failed in Phase 3 just two years post-close, and the already-approved epothilone Ixempra never became a meaningful revenue driver, getting offloaded to R-Pharm US in 2015 for a fraction of the deal price.
BMS's $190M Kosan bet fizzled: lead Hsp90 candidate killed in Phase 3, and the epothilone asset (already approved pre-deal) was quietly offloaded to R-Pharm seven years later for a fraction of the purchase price.
Full analysis, sources & comparables →BMS announces $5.50/share cash tender ($190M net) to acquire Kosan, citing pipeline enhancement with Hsp90 inhibitors and epothilones.
Acquisition adds two anticancer compound classes to BMS pipeline; transaction expected to close third quarter 2008.
Source summaries from our enrichment pipeline; follow links for originals.
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$5.50/share cash tender; Hsp90 inhibitors, epothilones; closed June 26 2008
BMS's $190M Kosan bet fizzled: lead Hsp90 candidate killed in Phase 3, and the epothilone asset (already approved pre-deal) was quietly offloaded to R-Pharm seven years later for a fraction of the purchase price.
Assessment window: 15yr post-close.
Kosan's lead programs targeted refractory multiple myeloma (Hsp90 inhibitor tanespimycin) and solid tumors (epothilone KOS-862/KOS-1584). Hsp90 is a chaperone protein cancer cells exploit to stabilize oncogenic clients; epothilones are microtubule stabilizers chemically distinct from taxanes intended to overcome taxane resistance.
At the time of the 2008 deal, the epothilone class was led by BMS's own Ixempra (ixabepilone), approved October 2007 for metastatic breast cancer, plus Novartis's patupilone in late-stage trials and Bayer/Schering's sagopilone in Phase 2. Hsp90 inhibitors were a crowded but unproven class: Infinity's IPI-504 (retaspimycin), Synta's STA-9090 (ganetespib), Pfizer's SNX-2112, and Astellas/OSI's KW-2478 were all in early development with no approvals. Kosan's tanespimycin (17-AAG) was the most clinically advanced Hsp90 inhibitor and showed activity in combination with bortezomib in relapsed/refractory multiple myeloma. The acquisition gave BMS pipeline depth behind Ixempra (next-generation epothilones with potentially better PK and CNS penetration) and an entry into the Hsp90 class. BMS ultimately discontinued tanespimycin development in 2010 citing intellectual property and supply considerations; the epothilone follow-ons also did not advance to approval, making this one of the era's lower-yielding $200M-range bolt-ons.
| Deal | Year | Value | Outcome |
|---|---|---|---|
| Bristol-Myers Squibb Company / Kosan Biosciences Incorporated (this deal) | 2008 | $190M | 22 |
| Bristol-Myers Squibb Company / Medarex Inc. | 2009 | $2.4B | 92 |
| Bristol-Myers Squibb Company / Celgene Corporation | 2019 | $74.0B | 77 |
| Bristol-Myers Squibb Company / MyoKardia Inc. | 2020 | $13.1B | 76 |
| Bristol-Myers Squibb Company / Karuna Therapeutics | 2023 | $14.0B | 76 |
| Bristol-Myers Squibb Company / Ono Pharmaceutical Co., Ltd. | 2011 | — | 76 |
| Bristol-Myers Squibb Company / SystImmune Inc. | 2023 | $8.4B | 71 |