Dominos gains on Q1 same-store sales beat

** Shares of pizza giant Domino's Pizza DPZ up 4% at $517 premarket

** Co beat expectations for Q1 same-store sales as consumers in US tap into its loyalty program and other promotions

** Q1 same-store sales rise 5.6% vs est. of 4.04% - LSEG

** Posts Q1 total revenue of $1.09 bln vs est. of $1.08 bln

** Earns EPS of $3.58 per share, compared with LSEG est. of $3.39

** As of last close, DPZ up 21.07% YTD