SAN DIEGO – Imbruvica (ibrutinib), the Bruton's tyrosine kinase (BTK) inhibitor that has racked up FDA approvals in B-cell cancers such as mantle cell lymphoma, chronic lymphocytic leukemia and Waldenström's macroglobulinemia has impressed in a non-oncology indication, chronic graft-vs.-host disease (cGVHD), with phase II data showing an overall response rate (ORR) of 67 percent.