Efficacy and Safety of Low-dose Ibrutinib and Itraconazole in Chronic Graft Versus Host Disease

Chronic graft-versus-host disease (cGVHD) affects 30 to 70% of Allogeneic Hematopoietic Cell Transplantation, decreases the quality of life, and increases mortality. First-line treatments for cGVHD are steroids, however, up to 50% of patients do not respond to treatment. There is no well-defined second-line treatment for cGVHD, but ibrutinib, a Bruton tyrosine kinase inhibitor, has been successfully used in phase 2 clinical trials for moderate to severe steroid-refractory cGVHD and has been shown to be safe, showing rates of response of 69% at a median follow-up of 26 months. Therefore, ibrutinib was approved by the FDA for the treatment of steroid-refractory cGVHD. Also, it is known that ibrutinib is metabolized by cytochrome isoenzyme 3A4 and that itraconazole is a potent inhibitor of this hepatic isoenzyme. Therefore, the investigators hypothesized that in subjects with newly diagnosed cGVHD and in patients with steroid-refractory cGVHD, low-dose ibrutinib in combination with itraconazole might be effective and safe.