A novel compound of the formula (1): wherein X is a tyrosine residue or a methionine residue; Y and Z each are a single bond or the like; R1 is a hydrogen atom or the like; R2 is a hydroxy group or the like; R3 is a hydrogen atom, alkyl group, amino group or the like; R4 is a hydrogen atom, alkyl group, carboxy group or the like; m is 1 or 2; and n is an integer of 0 to 2, with the proviso that when n is 0, R3 is a hydrogen atom or an alkyl group, or a pharmaceutically acceptable salt thereof, and its use in cancer immunotherapy.