Apparently someone removed the Guest DJ - Katy Perry from iTunes Radio.
https://itunes.apple.com/us/station/idra.691034299
All I can find so far is a Sound Cloud of her commentary
http://www.katyperrylately.com/post/61911940044/katy-perry-itunes-radio-guest-dj-commentary
Luckily, there is a listing of tracks that were played here
http://katyperryforum.com/index.php?topic=15310.0
https://itunes.apple.com/us/station/idra.691034299
All I can find so far is a Sound Cloud of her commentary
http://www.katyperrylately.com/post/61911940044/katy-perry-itunes-radio-guest-dj-commentary
Luckily, there is a listing of tracks that were played here
http://katyperryforum.com/index.php?topic=15310.0