* Background:
* Chronic graft-versus-host disease (cGVHD) is the leading cause of non-relapse morbidity and mortality in persons after allogeneic hematopoietic stem cell transplantation (SCT).
* Approximately 50% of patients with cGVHD have disease refractory to systemic corticosteroids; currently, there is no standard second-line therapy.
* The Janus kinase/signal transducers and activators of transcription (JAK/STAT) pathway relays the signaling function of several inflammatory cytokines that have a role in GVHD (interferon (IFN)-gamma, Interleukin-2 (IL-2), Interleukin-6 (IL-6), Interleukin-12 (IL-12)).
* Murine models have demonstrated activity of JAK inhibitors in graft-versus-host disease.
* Baricitinib is a potent and selective inhibitor of Janus kinase 1 (JAK1) and Janus kinase 1 (JAK2) that has demonstrated anti-inflammatory effects and a good safety profile in patients with rheumatoid arthritis but has not been evaluated in GVHD.
* Objectives:
* To determine the safety and tolerability of baricitinib in patients with cGVHD that is refractory to steroids
* To determine the efficacy of baricitinib in patients with cGVHD that is refractory to steroids
* Eligibility:
* Inclusion:
* Age greater than or equal to 18 years
* Moderate or severe cGVHD per NIH consensus criteria
* Karnofsky performance status greater than or equal to 50%
* cGVHD that did not respond to high-dose corticosteroids (prednisone at 1.0 mg/kg/day for at least 1 week or prednisone at 0.5 mg/kg/day or 1 mg/kg every other day for at least 4 weeks), or second-line therapy (any)
* Receiving stable or tapering doses of systemic therapy in the preceding 4 weeks if taking systemic therapy for cGVHD
* Exclusion:
* Neutrophils \<1.0x10\^9/L, platelets \<50X10\^9/L, creatinine greater than or equal to 1.5 times the upper limit of normal or estimated creatinine clearance \<50mL/min/1.73m\^2 (Cockroft-Gault formula), serum aspartate aminotransferase or alanine aminotransferase concentration \>3x upper limit of normal (ULN) or total bilirubin greater than or equal to 1.5x ULN
* Progressive malignancy, uncontrolled infection or any major organ dysfunction as defined by the protocol
* Design:
* This is a Phase 1/2 trial to determine the safety and efficacy of baricitinib in patients with cGVHD that is refractory to steroids.
* Patients will initially be treated with baricitinib at 2mg daily for 12 weeks. If the response at 12 weeks is a complete response (CR) and there has not been a dose-limiting toxicity (DLT), the dose will remain at 2mg daily for an additional 12 weeks, with the primary response assessment at 24 weeks of total treatment. If the response is a partial response (PR) or stable disease, the dose will be increased to 4mg daily for an additional 12 weeks, with the primary response assessment at 24 weeks of total treatment. If there is progression of disease at any time within the first 12 weeks, the dose can be increased to 4mg daily at that time, and patients will continue for a total of 24 weeks of treatment. Patients will have the option to continue baricitinib for an additional 6 months as tolerated if they have stable or responding disease.
* The co-primary endpoint of safety will be determined by rate, severity, and duration of adverse events based on Common Terminology Criteria for Adverse Events (CTCAE) v4 criteria. Assessment for DLTs will occur every 2 weeks during the first 4 weeks of each dose level. Safety monitoring will occur every 4 weeks thereafter.
* The co-primary endpoint of efficacy will be defined as rate of overall response at 24 weeks per National Institutes of Health (NIH) consensus criteria (CR or PR).
* Peripheral blood samples will be collected prior to treatment, at 2 weeks, at 12 weeks and every 12 weeks thereafter to evaluate cytokine and cellular profiles, STAT phosphorylation, candidate chronic GVHD biomarkers. Pharmacokinetic studies will also be performed at each dose level.
* In an initial futility analysis, if 0 of the first 7 patients enrolled in cohort 1 have responded at 12 weeks, then a 2nd cohort of patients will be accrued to start treatment at the higher dose (4mg daily). Otherwise, if 1 or more of the first 7 patients respond in cohort 1, then 21 evaluable patients will be treated in cohort 1. Similarly, if the second cohort is used, and if 0 of the 7 patients enrolled in this second cohort have responded at 12 weeks, then no further patients will be accrued. Otherwise, if 1 or more of the first 7 patients respond in cohort 2, then 21 evaluable patients will be treated in cohort 2.
* A total of 21 evaluable patients will be enrolled in either cohort 1 or 2 as appropriate, in order to have 80% power to detect a response rate consistent with 30% and ruling out 10%, with a one-sided significance level of 0.10 for the cohort. As an early stopping rule for safety, if 2/3 or greater patients at any given dose level experiences a dose limiting toxicity requiring dose reduction or discontinuation, that dose will not be subsequently used, and no further dose escalation will take place.
