I don't actually think ITV have an app, I may be wrong though - but on both Xbox and Samsung TV's I'm yet to see it - 4od is available on both however, but it's often to do with the brand of the TV making apps available, Panasonic may not have license to distribute the 4od app.
EDIT: Bit of research, ITV appear to have an app, but I'm still yet to see it on my tv/xbox.