What if a lycanthrope is transmutated into a non-commoner species?
That's a really good question. Could this be the "cure" to lycanthropy?
I think it highly depends on the skill of the transmutationist. Most transformations are just superficial, meaning they affect appearance, but everything "under the hood" stays the same.
I talked about this in more detail here and here.
Let's say a transmutationist transforms a human lycanthrope into an elf.
If this is a shallow, superficial transmutation: the patient looks totally indistinguishable from a natural-born elf, but they will still give birth to human babies and transform into a werewolf under the full moon. This is because they still resemble a human under the skin, and the disease still has not been cleared from their body. Just like cosmetic surgery won't cure diabetes, a superficial transformation won't cure lycanthropy.
If this is a deep, cellular-level transmutation: the patient is totally indistinguishable from an elf on an atomic level. The transformation is so thorough that they can even cast spells and give birth to elven children. Lycanthropy is not compatible with elven DNA, meaning the disease can't survive in an elven body. So, the patient would stop transforming under the full moon, and for all intents and purposes, would be "cured".
However, there is a possibility that the disease wouldn't be fully eradicated. Maybe the transformation just caused it to lie dormant in their system, and under the right conditions it could be passed on. If this elf were to bite someone--or otherwise make blood-to-saliva contact on the night of the full moon, it's possible they could infect a commoner with lycanthropy.
TL;DR: This might be a viable "cure" for lycanthropy, but it might also turn the patient into a Typhoid Mary.