Allogeneic haematopoietic stem cell transplantation (HCT) is a potent immunotherapy with curative potential for several haematological disorders. Overcoming the immunological barrier of acute graft-versus-host disease (GVHD) remains a fundamental impediment to expanding the efficacy of HCT. GVHD reflects a complex pathological interaction between the innate and adaptive immune systems of the host and donor. Over the past decade there has been a tremendous advancement in our understanding of the cellular and molecular underpinnings of this devastating disease. In this review, we cover several recently appreciated facets of GVHD pathogenesis including novel extracellular mediators of inflammation, immune subsets, intracellular signal transduction, post-translation modifications and epigenetic regulation. We begin to develop general themes regarding the immunological pathways in GVHD pathogenesis, discuss critical outstanding questions, and explore new avenues for GVHD treatment and prevention.

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Corticosteroid-refractory graft-versus-host disease (SR-GVHD) remains a significant source of morbidity after allogeneic hematopoietic cell transplantation. No standard therapy exists in this setting; however, recent studies have demonstrated a very promising role for ruxolitinib, an oral Janus kinase 1/2 inhibitor. With increasing evidence of efficacy for SR-GVHD, limited data exist describing complications of ruxolitinib use, specifically infectious complications during use in SR-GVHD. In this study we report outcomes and infectious complications at our institution with ruxolitinib use. Overall, 43 patients were treated with ruxolitinib for SR-GVHD, 19 for acute SR-GVHD and 24 for chronic SR-GVHD. With respect to acute SR-GVHD, 15 patients had grade III acute GVHD and 4 patients had grade IV acute GVHD. At 28 days, a response rate of 84% was detected. With respect to chronic SR-GVHD, 16 patients had moderate refractory disease and 8 had severe refractory disease. At around 28 days, a 63% response rate was detected. Overall, 42% of patients (n = 18) treated with ruxolitinib had a documented infectious event. Infectious events were significantly more common among patients treated for acute SR-GVHD (P < .005). Among patients treated for acute SR-GVHD, both viral (n = 11) and bacterial (n = 10) events were frequently encountered. Cytomegalovirus reactivation was detected in 4 patients without organ involvement in any patient. Bacteremia was the most common bacterial event (n = 8), and 2 patients died after development of bacteremia. Only 5 of 24 patients treated with ruxolitinib for chronic SR-GVHD developed infectious complications after initiation of therapy. Nearly an even number of viral (n = 3) and bacterial (n = 4) were detected. This study supports the use of ruxolitinib in SR-GVHD, with impressive responses observed in both acute and chronic SR-GVHD. Infectious complications were particularly frequent among patients treated for acute SR-GVHD, and nearly all these patients were concurrently on high-dose steroids while on ruxolitinib. This study suggests careful monitoring for viral reactivation is required for patients initiated on ruxolitinib, supports the role of continuing prophylactic antimicrobial measures in ruxolitinib-treated GVHD patients, and raises the question of whether bacterial prophylaxis should be considered among patients initiated on ruxolitinib for acute SR-GVHD, particularly while on high-dose steroids.

A B S T R A C THealth information technology (HIT) has great potential for increasing patient engagement. Pediatric hematopoietic cell transplantation (HCT) is a setting ripe for using HIT but in which little research exists. "BMT Roadmap" is a web-based application that integrates patient-specific information and includes several domains: laboratory results, medications, clinical trial details, photos of the healthcare team, trajectory of transplant process, and discharge checklist. BMT Roadmap was provided to 10 caregivers of patients undergoing firsttime HCT. Research assistants performed weekly qualitative interviews throughout the patient's hospitalization and at discharge and day 100 to assess the impact of BMT Roadmap. Rigorous thematic analysis revealed 5 recurrent themes: emotional impact of the HCT process itself; critical importance of communication among patients, caregivers, and healthcare providers; ways in which BMT Roadmap was helpful during inpatient setting; suggestions for improving BMT Roadmap; and other strategies for organization and management of complex healthcare needs that could be incorporated into BMT Roadmap. Caregivers found the tool useful and easy to use, leading them to want even greater access to information. BMT Roadmap was feasible, with no disruption to inpatient care. Although this initial study is limited by the small sample size and singleinstitution experience, these initial findings are encouraging and support further investigation.

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