Dragonfly Therapeutics Inc. added Gilead Sciences Inc. to its roster of partnerships in a deal that gives the Waltham, Mass.-based company $300 million up front, with opt-in payments, milestones and up to 20% royalties down the road. In exchange Foster City, Calif.-based Gilead gets exclusive, worldwide rights to DF-7001, a preclinical-stage immunotherapy, as well as rights to additional NK cell engager programs generated by Dragonfly’s TriNKET (Trispecific NK Engager) platform.