One simple regex would be: \b\w+(?=\r|\n|$)
This finds any word 1+ characters long with a word boundary on the left side (meaning newline, whitespace, start of the string) and finds either a newline or the end of the string on the right side of those 1+ characters it found. It will find any alphanumeric characters, along with decimal points and underscores. If you only want alphanumeric then switch the \w with [A-Z,a-z,0-9] instead.
You can put this in an assign activity to return a string back like this: Assign YourString = System.Text.RegularExpressions.Regex.Match(InputString,"\b\w+(?=\r|\n|$)").Value