According to Circassia, Ltd., which is in the process of human clinical trials of their upcoming cat allergy vaccine, ToleroMune®, they have achieved promising results from their phase II clinical study. As their recent media release states:
Circassia Ltd, a specialty biopharmaceutical company focused on controlling immune system responses, today announced positive results from a phase II clinical study of its anti-allergy technology, ToleroMune®, in the field of cat allergy. The trial showed that ToleroMune treatment can substantially reduce allergic reactions to the allergen that causes most cat allergies, and importantly was well tolerated by all patients.
More information is available here.