Sanofi and Regeneron launched a major immuno-oncology collaboration in 2015, with Sanofi committing up to $2.17B including $640M in upfront payments. This expanded their long-standing antibody alliance that originated in 2003 and had produced Dupixent (dupilumab), Praluent (alirocumab), and other antibody therapeutics. The I-O collaboration was later restructured in 2019 when Sanofi paid $462M to exit.