Regular expression remove the letters on the sides

Regular expression remove the letters on the sides

Hello Can't find expression which can remove all letter on the sides. Data
sample: "Valencia 7x16/5x114.3 D71.6 ET48 Dark". Need remove all letters
on sides, such as "Valencia" and "Dark", thous 2 word just sample there
might be any text characters.
[^x./ETD\s0-9]