** Precision oncology co Erasca's ERAS.O shares down 2.2% at $17.50 in premarket trading on Tues after $550 mln follow-on priced

** San Diego, California-based biotech late Mon sold ~31.4 mln shares at $17.50, a 2.2% discount to last sale

** Co after the bell Mon unveiled $500 mln stock offering and announced updated Phase 1 data for ERAS-0015 in patients with solid tumors caused by mutations in the RAS gene

** Co intends to use net offering proceeds to fund R&D of its product candidates, other development programs, among other purposes

** JP Morgan, Morgan Stanley, Jefferies and Evercore joint bookrunners

** On Apr 28, ERAS shares tumbled 48% after co said a patient died in an early-stage trial of ERAS-0015

** Still, stock has risen nearly fivefold YTD giving co roughly $5.6 bln market cap

** 9 of 11 analysts rate the stock "strong buy" or "buy", 2 "hold"; median PT $20, per LSEG data