Bristol-Myers Squibb is beefing up its fast-growing fibrosis portfolio after paying $100 million upfront to Japanese biopharma Nitto to develop and sell its early-stage liver-scarring candidate–as well as an option to buy into other antifibrotic meds.

Under the deal, BMS gains exclusive worldwide rights to Nitto’s investigational siRNA molecules targeting heat shock protein 47 (HSP47) in vitamin A-containing formulations–which includes Nitto’s lead asset ND-L02-s0201, currently in Phase Ib for advanced liver fibrosis due to nonalcoholic fatty liver disease, or NASH, as well as scarring due to hep C infection.