Bristol-Myers Squibb has signed a definitive agreement to acquire all of the outstanding capital stock of Flexus Biosciences, a San Carlos, Calif.-based, privately held biotech focused on the discovery and development of novel anti-cancer therapeutics. The transaction has a potential total consideration of $1.25 billion, including $800 million upfront and development milestones that, upon achievement, could total up to $450 million. The transaction has been approved by the boards of directors of both companies and by the stockholders of Flexus.

The acquisition will give BMS full rights to F001287, Flexus’ lead preclinical small molecule IDO1-inhibitor targeted for IND filing in the second half of 2015. In addition, BMS will acquire Flexus’ IDO/TDO discovery program, which includes its IDO-selective, IDO/TDO dual and TDO-selective compound libraries. A newly formed entity established by the current shareholders of Flexus will retain, from and after the closing, all non-IDO/TDO assets of Flexus including those related to Flexus’ hase I FLT3 and CDK4/6 inhibitor, its earlier stage small-molecule Treg cancer immunotherapy programs and its current personnel and facilities.

“Bristol-Myers Squibb is committed to leading scientific advances in immuno-oncology and our acquisition of Flexus will expand our innovative pipeline with an important approach to enhancing immune responses in cancer,” said Francis Cuss, MB BChir, FRCP, executive vice president and chief scientific officer, BMS. “With the addition of a potentially best-in-class IDO1 inhibitor and the broad IDO/TDO programs, Bristol-Myers Squibb will accelerate its ability to explore numerous immunotherapeutic approaches across tumor types, including combinations with our biologic checkpoint and co-stimulatory agents that target different and complementary pathways.”

Terry Rosen, Ph.D., CEO of Flexus Biosciences, said, “With the consummation of this acquisition, we will continue to advance our oncology and immuno-oncology pipeline of Agents for Reversal of Tumor Immunosuppression (ARTIS) in the newly created spin-off, with the strong support of our committed group of investors.”

BMS and Flexus anticipate the transaction will close during the first quarter of 2015. Closing of the transaction is subject to customary closing conditions, including clearance under the Hart-Scott-Rodino Antitrust Improvements Act.