I have that bag in a different color - so cute!
Maybe it was beginner's luck, but I completely erased a pen mark on a white
Coach using Leather Dye Transfer Cleaner. I got it off
Amazon. I've had zero luck removing ink on any other color bag - LDTC just leaves a light spot. For those, I had to use acrylic mixed w/ conditioner or Leather Refinisher to cover.
I remember reading about someone using zit cream to bleach out marks on a white bag. You might search this thread (or archived versions of this thread) for that.
Good luck!