Apoquel is not approved for use in cats and I have no personal experience using it in cats. So for now, I am not ready to suggest you use it in your cat. But one Company study on its use in cats to lessen the symptoms of allergic skin disease was promising. (ref) Two 2015 reports and a 2016 summary were a bit less so. (ref1 ref2 ref3)
When cats are diagnosed as having allergic dermatitis or eosinophilic granuloma complex , there are veterinarians in 2017 who will already dispense this medication to their client's cats. Getting a new label use approved by the FDA or the EMA is a lengthy, expensive process. So many drug companies will opt to just let veterinarians take the lead and establish an accepted "off label" use.
So we might just have to wait and see how things go through feedback from cat owners like you and veterinary chatter.
If you have used Apoquel in your cat, please let me know how your cat did and I will post your observations
here for other readers to see.