Complete Resolution of Extensive Chronic Graft-Versus-Host Disease with Ibrutinib

We herein document a complete response of extensive chronic graft-versus-host disease (cGvHD) to a Bruton's tyrosine kinase (BTK) inhibitor, ibrutinib. A 41 years old female with primary refractory MCL underwent mismatched unrelated donor (MMUD) allogeneic hematopoietic stem cell transplantation in December 2011 (conditioning with CY/TBI and alemtuzumab, graft=6.6x 106/kg CD-34+ cells, tacrolimus alone for GVHD prevention). Following engraftment on day 11, she developed grade III acute GvHD involving the skin and gut on day 17 of transplantation that persisted beyond 100 days post-transplant. Her cGvHD was treated with steroids, but remained active and extensive. Despite persistent cGvHD and 100% donor chimerism she relapsed in July 2012. Treatment with radiation and bendamustine with rituximab failed. By December 2013, the patient had extensive cGvHD manifesting as scleromatous skin thickening, oral ulcers and sclerosis of the buccal mucosa, ocular dryness and diarrhea, and was started on ibrutinib1 560 mg once daily for relapsed MCL. After 8 weeks of therapy, cGvHD had begun to improve. Oral steroids were reduced and ultimately stopped after 26 weeks of ibrutinib; after 30 weeks treatment all cGvHD manifestations resolved completely. A complete remission for MCL was documented at 8 weeks of ibrutinib initiation. Currently she continues to be on 560 mg daily ibrutinib without cGvHD exacerbation or MCL relapse for 22 weeks and 52 weeks, respectively. Chronic graft versus host disease (cGvHD) is mediated donor T cells. The role of B cells in the pathogenesis of cGvHD is increasingly recognized. Two murine studies have explored the role of ibrutinib in cGVHD-like syndromes, one in which there is T cell driven sclerodermatous cGvHD and a second in which there is Ab driven multiorgan system cGvHD that includes bronchiolitis obliterans (BO). Administration of ibrutinib decreased the incidence and severity of sclerodermatous, and improved pre-existing lesions and also improved pulmonary fibrosis and reduced BO. Animals lacking BTK and ITK did not develop cGVHD, indicating that these molecules are critical to cGVHD development. Our report provides the evidence that BTK inhibition led to complete resolution of cGvHD and supports exploration of its role in future clinical trials.