Like I said above I haven't been told that was an issue but I will try and research it and talk to some vets about it.
I am thinking, if your cat is responding well to the pred, why would a vet recommend a chemo drug?? most cats tolerate pred very well, and it is for inflammation. Stephen, what do you think of Emily Ann's concern about Leukeran being less effective if administered later, if the cat is doing well on pred?