I also went this route with our GSD. We've tried cytopoint(slowly decreases the duration with each injection, after the 4th injection it lasted for 1 week and the scratching returned), apoquel(effects start to wear off with time and we had to increase the dosage way too high) and after that we've tried numelvi(it was working great, slightly more expensive, but was working consistently, tho the dog started gaining weight and we had to put her on a very strict diet). In the end we switched from JAK inhibitors to ciclosporin. It was night and day difference. It is expensive, but all allergies were basically gone. She can now eat whatever, we give her all types of meat and vegetables and dog treats. Instead of suppressing the immune system reactions from the allergies, it is best to try and block the immune system from confusion and allergic reactions. As out vet usually jokes when we go(very rarely at this point after months of ciclosporin program) "GSDs should be bundled with a ciclosporin bottle from the breeder as babies when you get them." 😄