Chronic graft-versus-host disease: biological insights from preclinical and clinical studies

Reconstituted CD74+ NK cells trigger chronic graft versus host disease after allogeneic bone marrow transplantation

Chronic graft-versus-host disease (cGVHD) is the most common long-term complication after allogeneic hematopoietic stem cell transplantation (allo-HSCT). The patients with pulmonary cGVHD in particular have a very poor prognosis. NK cells are the first reconstituted lymphocyte subset after allo-HSCT; however, the impact of reconstituted NK cells on cGVHD is unclear. Here, we found allogeneic recipients showed obvious pulmonary cGVHD. Surprisingly, deletion of reconstituted NK cells resulted in maximal relief of pulmonary cGVHD. Mechanistically, reconstituted NK cells with donor profiles modulated the pulmonary inflammatory microenvironment to trigger cGVHD. Reconstituted NK cells secreted IFN-γ and TNF-α to induce CXCL10 production by epithelial cells, which recruited macrophages and CD4+ T cells to the lungs. Then macrophages and CD4+ T cells were activated by the inflammatory microenvironment, thereby mediating lung injury. Through assessment of differences in cellular energy, we found that CD74+ NK cells with high mitochondrial potential and pro-inflammatory activity triggered pulmonary cGVHD. Furthermore, targeted elimination of CD74+ NK cells using the anti-CD74 antibody significantly alleviated pulmonary cGVHD but preserved the CD74- NK cells to exert graft-versus-leukemia (GVL) effects. Data from human samples corroborated our findings in mouse models. Collectively, our results reveal that reconstituted CD74+ NK cells trigger pulmonary cGVHD and suggest that administration of CD74 antibody was a potential therapeutic for patients with cGVHD.

Efficacy and safety of ruxolitinib in the treatment of chronic graft-versus-host disease: a retrospective analysis

Steroid-refractory chronic graft-versus-host disease (cGvHD) is associated with significant morbidity and mortality, with ruxolitinib being the first drug approved for its treatment. We retrospectively analyzed the safety and efficacy of ruxolitinib for treatment of cGvHD at our center between 07/2015 and 12/2022 and identified 48 patients receiving ruxolitinib as second (18/48) or advanced (30/48) treatment line. Ruxolitinib was started on median day 340 (range 119-595) after cGvHD onset; median duration of administration was 176 (range, 79-294) days with 16/48 patients continuing treatment at last follow-up. National Institutes of Health organ grading and the intensity of immunosuppression were assessed at the start of ruxolitinib treatment and repeated after 1, 3, 6, and 12 months. Response assessment was terminated at the start of any additional new immunosuppressant treatment. The median time of follow-up was 582 (range, 104-1161) days. At the primary analysis after six months on ruxolitinib treatment, the overall response rate was 33%, and failure-free survival was 58%. Infectious adverse events ≥ CTCAE grade III were observed in 10/48 patients. The response rate was not associated with the severity of cGvHD, number of previous treatment lines, or number of additional agents combined with ruxolitinib applying a univariate regression model. At the time of the 12-month follow-up, four patients experienced recurrence of the underlying malignancy and two patients had experienced non-relapse-related mortality. Overall, ruxolitinib was relatively well-tolerated and showed outcomes comparable to the REACH3 trial in a heavily pretreated patient population.

Calcineurin inhibition rescues alloantigen-specific central memory T cell subsets that promote chronic GVHD

Calcineurin inhibitors (CNIs) constitute the backbone of modern acute graft-versus-host disease (aGVHD) prophylaxis regimens but have limited efficacy in the prevention and treatment of chronic GVHD (cGVHD). We investigated the effect of CNIs on immune tolerance after stem cell transplantation with discovery-based single-cell gene expression and T cell receptor (TCR) assays of clonal immunity in tandem with traditional protein-based approaches and preclinical modeling. While cyclosporin and tacrolimus suppressed the clonal expansion of CD8+ T cells during GVHD, alloreactive CD4+ T cell clusters were preferentially expanded. Moreover, CNIs mediated reversible dose-dependent suppression of T cell activation and all stages of donor T cell exhaustion. Critically, CNIs promoted the expansion of both polyclonal and TCR-specific alloreactive central memory CD4+ T cells (TCM) with high self-renewal capacity that mediated cGVHD following drug withdrawal. In contrast to posttransplant cyclophosphamide (PT-Cy), CSA was ineffective in eliminating IL-17A-secreting alloreactive T cell clones that play an important role in the pathogenesis of cGVHD. Collectively, we have shown that, although CNIs attenuate aGVHD, they paradoxically rescue alloantigen-specific TCM, especially within the CD4+ compartment in lymphoid and GVHD target tissues, thus predisposing patients to cGVHD. These data provide further evidence to caution against CNI-based immune suppression without concurrent approaches that eliminate alloreactive T cell clones.

Hematopoietic Stem-Cell Transplantation: Exploring the Latest Advances and Gaps in Disparities, Psychosocial and Symptom Management Interventions, and Chronic Graft-Versus-Host Disease Care

Although allogeneic hematopoietic cell transplantation (HCT) offers a potential for cure for many patients with advanced hematologic malignancies and bone marrow failure or immunodeficiency syndromes, it is an intensive treatment and accompanied by short- and long-term physical and psychological symptoms requiring specialized care. With substantial advances in therapeutic approaches for HCT and supportive care, HCT survivors experience less morbidity and mortality. However, disparities in both HCT access and outcomes persist, and HCT survivors and their caregivers often lack access to much-needed psychosocial care. Additionally, more medical and psychosocial resources are needed to holistically care for HCT survivors with chronic graft-versus-host disease (GVHD). Hence, this chapter focuses on three areas pertaining to advances and gaps in HCT care: disparities in access to and outcomes of HCT, psychosocial and physical symptom management with supportive care interventions, and GVHD prevention and management.

Two-Part Phase 1 Study to Evaluate the Taste Profile of Novel Belumosudil Oral Suspensions and Assess the Relative Bioavailability and Food Effect of the Selected Belumosudil Oral Suspension Compared With Oral Tablet Reference in Healthy Male Participants

Belumosudil is a selective rho-associated coiled-coil-containing protein kinase 2 inhibitor in clinical use for the treatment of chronic graft-versus-host disease. The current tablet formulation may be inappropriate for children or adults with dysphagia and/or upper gastrointestinal manifestations of chronic graft-versus-host disease. This study (NCT04735822) assessed the taste and palatability of oral suspensions of belumosudil, evaluated the relative bioavailability of an oral suspension versus the tablet formulation, and characterized the effect of food on the pharmacokinetics of an oral suspension. Addition of sweetener and/or flavor vehicle improved the taste. Relative bioavailability of 200-mg doses of the oral suspension and tablet in the fed state was similar for belumosudil and its metabolites (KD025m1 and KD025m2), but absorption was faster with the oral suspension (median time to maximum concentration: 2 vs 3 hours). Administration of the oral suspension with food increased exposure compared with fasted administration, with maximum observed concentration being increased by 16% and area under the concentration-time curve from time 0 to the last measurable concentration (AUC0-last) by 19%. Safety and tolerability were consistent with the known safety profile of belumosudil. These results may support administration of a 200-mg belumosudil oral suspension with or without food.

Characterization of orofacial features in sclerodermatous chronic graft-versus-host disease

BACKGROUND

Chronic graft-versus-host disease (cGVHD) is a leading cause of morbidity and mortality following allogeneic hematopoietic cell transplantation (alloHCT). The sclerodermatous form of cGVHD can be particularly debilitating; however, orofacial sclerodermatous involvement remains poorly described.

OBJECTIVE

To characterize orofacial features of sclerodermatous cGVHD in a single center cohort of patients who underwent alloHCT.

STUDY DESIGN

Retrospective data were collected from electronic medical records and analyzed descriptively.

RESULTS

There were 39 patients who received alloHCT between 1993 and 2017 and developed orofacial sclerodermatous cGVHD. Concomitant cutaneous sclerodermatous cGVHD was common (n = 20, 51%). Orofacial sclerodermatous cGVHD features included fibrous bands of the buccal mucosa (n = 23, 59%), limited mouth opening (n = 19, 54%), perioral fibrosis (n = 8, 21%), and focal gingival recession (n = 4, 10%). Oral mucosal fibrosis was observed at the site of active or resolved chronic lichenoid inflammation in 30 patients, with all but two also presenting with a history of ulcerations. Management included jaw stretching exercises (n = 10; 6 stable/improved), surgery (n = 3; 2 improved), and intralesional corticosteroid injections (n = 2; 2 improved).

CONCLUSIONS

Orofacial involvement with sclerodermatous cGVHD can present with multiple manifestations including fibrous banding, limited mouth opening, perioral fibrosis, and focal gingival recession. Surgical and non-surgical management strategies may improve clinical function and reduce morbidity.

CSF1R inhibition promotes neuroinflammation and behavioral deficits during graft-versus-host disease in mice

ABSTRACT

Chronic graft-versus-host disease (cGVHD) remains a significant complication of allogeneic hematopoietic stem cell transplantation. Central nervous system (CNS) involvement is becoming increasingly recognized, in which brain-infiltrating donor major histocompatibility complex (MHC) class II+ bone marrow-derived macrophages (BMDM) drive pathology. BMDM are also mediators of cutaneous and pulmonary cGVHD, and clinical trials assessing the efficacy of antibody blockade of colony-stimulating factor 1 receptor (CSF1R) to deplete macrophages are promising. We hypothesized that CSF1R antibody blockade may also be a useful strategy to prevent/treat CNS cGVHD. Increased blood-brain barrier permeability during acute GVHD (aGVHD) facilitated CNS antibody access and microglia depletion by anti-CSF1R treatment. However, CSF1R blockade early after transplant unexpectedly exacerbated aGVHD neuroinflammation. In established cGVHD, vascular changes and anti-CSF1R efficacy were more limited. Anti-CSF1R-treated mice retained donor BMDM, activated microglia, CD8+ and CD4+ T cells, and local cytokine expression in the brain. These findings were recapitulated in GVHD recipients, in which CSF1R was conditionally depleted in donor CX3CR1+ BMDM. Notably, inhibition of CSF1R signaling after transplant failed to reverse GVHD-induced behavioral changes. Moreover, we observed aberrant behavior in non-GVHD control recipients administered anti-CSF1R blocking antibody and naïve mice lacking CSF1R in CX3CR1+ cells, revealing a novel role for homeostatic microglia and indicating that ongoing clinical trials of CSF1R inhibition should assess neurological adverse events in patients. In contrast, transfer of Ifngr-/- grafts could reduce MHC class II+ BMDM infiltration, resulting in improved neurocognitive function. Our findings highlight unexpected neurological immune toxicity during CSF1R blockade and provide alternative targets for the treatment of cGVHD within the CNS.

Impact of Center Volume on Chronic Graft Versus Host Disease in Patients With Allogeneic Stem Cell Transplantation

Chronic graft-versus-host disease (cGVHD) is a complication of allogeneic hematopoietic stem cell transplantation (HSCT), negatively impacting quality of life (QoL) and increasing the risk of death. Complexity in cGVHD diagnosis and treatment causes significant variations in cGVHD management strategies across medical centers and physicians despite the existence of published guidelines. Thus, we hypothesized that center volume is associated with cGVHD incidence and outcomes after cGVHD develops. This study aimed to evaluate the effect of center volume on the incidence of cGVHD in patients who underwent HSCT and outcomes in patients with cGVHD. Our retrospective study included 28,786 patients who underwent their first HSCT (overall cohort) and 7664 who developed cGVHD (cGVHD cohort). We categorized institutions into quartiles (very low, low, high, and very high) using the number of HSCTs performed during the study period. We assessed cGVHD incidence in overall cohort and overall survival (OS) in cGVHD cohort. The very high-volume group showed significantly higher cGVHD incidence (adjusted hazard ratio [HR], 1.38; 95% confidence interval [CI]: 1.30 to 1.46) compared to the very low-volume group. However, the cGVHD incidence was similar among very low-, low- and high-volume groups. Low, high, and very high-volume groups showed significantly higher OS with adjusted HRs of 0.83 (95% CI: 0.73 to 0.94), 0.69 (95% CI: 0.61 to 0.79), and 0.68 (95% CI: 0.60 to 0.76), respectively, compared with the very low-volume group. In conclusion, we revealed a higher incidence of cGVHD in the very high-volume group and a poor survival outcome in the very low-volume group in patients with cGVHD.

Navigating the Complexity of Chronic Graft-vs-Host Disease: Canadian Insights into Real-World Treatment Sequencing

BACKGROUND

Graft-vs-Host Disease (GVHD) is a donor immune-mediated syndrome occurring in patients who undergo an allogeneic hematopoietic cell transplant (HCT). Chronic GVHD (cGVHD) presents with complications of variable severity. Corticosteroids are standard first-line (1L) treatment, but the sequence after 1L is unclear with the availability of new treatments. This research aimed to understand real-world treatment sequencing for cGVHD.

METHODS

This retrospective study investigated adult patients across 7 treatment sites in Canada who had received an allogeneic HCT >18 months prior to the study, experienced cGVHD, and received systemic treatment, including extracorporeal photopheresis (ECP).

RESULTS

A total of 77 cases were reviewed retrospectively (median age = 51 (IQR 41-62), 51% female). 59 patients remained on active systemic treatment, and among this group, the most common treatments in use were corticosteroids (47%) and ruxolitinib (47%). One patient died, and 17 patients were on non-systemic treatment after complications resolved. The median lines of treatment (LOT) received was 2 (IQR 1-3), with 39% of patients having received >2 LOT. Among patients with lung complications (n = 24), 41% had received 3 or more LOT. Among patients with scleroderma (n = 22), 77% had received 3 or more LOT, 23% of which had received 6 or more unique treatments.

CONCLUSIONS

The first treatment given to cGVHD patients was corticosteroids. Ruxolitinib was the most used second-line treatment. About 40% of cGVHD patients received >2 treatments, and scleroderma was associated with more LOT. There is a need for more effective cGVHD treatment options when early treatments fail to resolve complications.

How does ocular graft-versus-host disease fit under the dry eye umbrella? A review

Graft-versus-host disease (GVHD) is a systemic disease that can affect multiple organs as a consequence of an allogeneic haematopoietic stem cell transplant. One organ system that is often affected in GVHD is the eyes. Ocular GVHD (oGVHD) may involve various structures within the eye including the lacrimal glands, eyelids, conjunctiva, cornea, and nasolacrimal ducts, and is a source of morbidity in patients with GVHD. Common presenting features of GVHD overlap with dry eye disease (DED), including decreased tear production, epithelial disruption, and Meibomian gland dysfunction (MGD). In this review, we aim to compare oGVHD and DED to better understand the similarities and differences between the conditions, with a focus on pathophysiology, risk factors, clinical features, and treatments.

Transcriptional landscape of macrophages in cutaneous graft-versus-host disease

We are submitting a comment on a study authored by: J. Strobel, L. M. Gail, L. Krecu, S. Madad, L. Kleissl, L. Unterluggauer, A. Redl, K. Brazdilova, S. Saluzzo, P. Wohlfarth, H. A. Knaus, M. Mitterbauer, W. Rabitsch, M. Haniffa and G. Stary, "Diverse macrophage populations contribute to distinct manifestations of human cutaneous graft-versus-host disease," British Journal of Dermatology, 2023.

Gut microbiota, microbiota-derived metabolites, and graft-versus-host disease

Allogeneic hematopoietic stem cell transplantation is one of the most effective treatment strategies for leukemia, lymphoma, and other hematologic malignancies. However, graft-versus-host disease (GVHD) can significantly reduce the survival rate and quality of life of patients after transplantation, and is therefore the greatest obstacle to transplantation. The recent development of new technologies, including high-throughput sequencing, metabolomics, and others, has facilitated great progress in understanding the complex interactions between gut microbiota, microbiota-derived metabolites, and the host. Of these interactions, the relationship between gut microbiota, microbial-associated metabolites, and GVHD has been most intensively researched. Studies have shown that GVHD patients often suffer from gut microbiota dysbiosis, which mainly manifests as decreased microbial diversity and changes in microbial composition and microbiota-derived metabolites, both of which are significant predictors of poor prognosis in GVHD patients. Therefore, the purpose of this review is to summarize what is known regarding changes in gut microbiota and microbiota-derived metabolites in GVHD, their relationship to GVHD prognosis, and corresponding clinical strategies designed to prevent microbial dysregulation and facilitate treatment of GVHD.

Chronic graft-versus-host disease detected by tissue-specific cell-free DNA methylation biomarkers

BACKGROUND

Accurate detection of graft-versus-host disease (GVHD) is a major challenge in the management of patients undergoing hematopoietic stem cell transplantation (HCT). Here, we demonstrated the use of circulating cell-free DNA (cfDNA) for detection of tissue turnover and chronic GVHD (cGVHD) in specific organs.

METHODS

We established a cocktail of tissue-specific DNA methylation markers and used it to determine the concentration of cfDNA molecules derived from the liver, skin, lungs, colon, and specific immune cells in 101 patients undergoing HCT.

RESULTS

Patients with active cGVHD showed elevated concentrations of cfDNA, as well as tissue-specific methylation markers that agreed with clinical scores. Strikingly, transplanted patients with no clinical symptoms had abnormally high levels of tissue-specific markers, suggesting hidden tissue turnover even in the absence of evident clinical pathology. An integrative model taking into account total cfDNA concentration, monocyte/macrophage cfDNA levels and alanine transaminase was able to correctly identify GVHD with a specificity of 86% and precision of 89% (AUC of 0.8).

CONCLUSION

cfDNA markers can be used for the detection of cGVHD, opening a window into underlying tissue dynamics in patients that receive allogeneic stem cell transplants.

FUNDING

This work was supported by grants from the Ernest and Bonnie Beutler Research Program of Excellence in Genomic Medicine, The Israel Science Foundation, the Waldholtz/Pakula family, the Robert M. and Marilyn Sternberg Family Charitable Foundation and the Helmsley Charitable Trust (to YD).

Neoself Antigens Presented on MHC Class II Molecules in Autoimmune Diseases

Major histocompatibility complex (MHC) class II molecules play a crucial role in immunity by presenting peptide antigens to helper T cells. Immune cells are generally tolerant to self-antigens. However, when self-tolerance is broken, immune cells attack normal tissues or cells, leading to the development of autoimmune diseases. Genome-wide association studies have shown that MHC class II is the gene most strongly associated with the risk of most autoimmune diseases. When misfolded self-antigens, called neoself antigens, are associated with MHC class II molecules in the endoplasmic reticulum, they are transported by the MHC class II molecules to the cell surface without being processed into peptides. Moreover, neoself antigens that are complexed with MHC class II molecules of autoimmune disease risk alleles exhibit distinct antigenicities compared to normal self-antigens, making them the primary targets of autoantibodies in various autoimmune diseases. Elucidation of the immunological functions of neoself antigens presented on MHC class II molecules is crucial for understanding the mechanism of autoimmune diseases.

Chronic graft-versus-host disease. Part I: Epidemiology, pathogenesis, and clinical manifestations

Chronic graft-versus-host disease is a major complication of allogeneic hematopoietic cell transplantation and a leading cause of long-term morbidity, nonrelapse mortality, and impaired health-related quality of life. The skin is commonly affected and presents heterogeneously, making the role of dermatologists critical in both diagnosis and treatment. In addition, new clinical classification and grading schemes inform treatment algorithms, which now include 3 U.S. Food and Drug Administration-approved therapies, and evolving transplant techniques are changing disease epidemiology. Part I reviews the epidemiology, pathogenesis, clinical manifestations, and diagnosis of chronic graft-versus-host disease. Part II discusses disease grading and therapeutic management.

CSF-1R inhibitor PLX3397 attenuates peripheral and brain chronic GVHD and improves functional outcomes in mice

Graft-versus-host disease (GVHD) is a serious complication of otherwise curative allogeneic haematopoietic stem cell transplants. Chronic GVHD induces pathological changes in peripheral organs as well as the brain and is a frequent cause of late morbidity and death after bone-marrow transplantation. In the periphery, bone-marrow-derived macrophages are key drivers of pathology, but recent evidence suggests that these cells also infiltrate into cGVHD-affected brains. Microglia are also persistently activated in the cGVHD-affected brain. To understand the involvement of these myeloid cell populations in the development and/or progression of cGVHD pathology, we here utilized the blood-brain-barrier permeable colony stimulating factor-1 receptor (CSF-1R) inhibitor PLX3397 (pexidartinib) at varying doses to pharmacologically deplete both cell types. We demonstrate that PLX3397 treatment during the development of cGVHD (i.e., 30 days post-transplant) improves disease symptoms, reducing both the clinical scores and histopathology of multiple cGVHD target organs, including the sequestration of T cells in cGVHD-affected skin tissue. Cognitive impairments associated with cGVHD and neuroinflammation were also attenuated by PLX3397 treatment. PLX3397 treatment prior to the onset of cGVHD (i.e., immediately post-transplant) did not change in clinical scores or histopathology. Overall, our data demonstrate significant benefits of using PLX3397 for the treatment of cGVHD and associated organ pathologies in both the periphery and brain, highlighting the therapeutic potential of pexidartinib for this condition.

Understanding and treatment of cutaneous graft-versus-host-disease

The skin is the outermost mechanical barrier where dynamic immune reactions take place and is the most commonly affected site in both acute and chronic graft-versus-host disease (GVHD). If not properly treated, pain and pruritis resulting from cutaneous GVHD can increase the risk of secondary infection due to erosions, ulcerations, and damage of underlying tissues. Furthermore, resulting disfiguration can cause distress and significantly impact patients' quality of life. Thus, a deeper understanding of skin-specific findings of GVHD is needed. This review will highlight some promising results of recent pre-clinical studies on the pathophysiology of skin GVHD and summarize the diagnostic and staging/grading procedures according to the clinical manifestations of skin GVHD. In addition, we will summarize outcomes of various GVHD treatments, including skin-specific response rates.

Targeting Hedgehog Signaling with Glasdegib in Patients with Refractory Sclerotic Chronic GVHD: A Report of Two Phase I/II Trials

PURPOSE

Sclerotic chronic GVHD (scGVHD) is characterized by progressive skin fibrosis and frequent refractoriness to available therapies. Aberrant activation of Hedgehog signaling in dermal fibroblasts has been implicated in scGVHD. Here, we report the results of two phase I/II studies (NCT03415867, GETH-TC; NCT04111497, FHD) that evaluated glasdegib, a smoothened antagonist, as a novel therapeutic agent in refractory scGVHD.

PATIENTS AND METHODS

Adult patients with active scGVHD after ≥1 (FHD) or ≥2 (GETH-TC) lines of therapy were enrolled. Primary endpoints were dose-limiting toxicity (DLT) and MTD in the GETH-TC trial, and safety and tolerability measures in the FHD trial. Glasdegib was administered once daily in 28-day cycles. Responses were scored per 2014 NIH cGVHD criteria. Correlative studies were performed to evaluate the role of fibroblast-independent immune mechanisms on clinical activity.

RESULTS

Twenty (GETH-TC) and 15 (FHD) patients were recruited. Treatment-emergent grade (G) ≥2 adverse events (AE) in the GETH-TC trial included muscle cramps (85%), alopecia (50%), and dysgeusia (35%). Two patients experienced a DLT (G3 muscle cramps), and the MTD was established at 50 mg. G3 muscle cramps were the most frequently reported AE (33%) in the FHD trial. At 12-months, the skin/joint scGVHD overall response rate was 65% (all partial responses) in the GETH-TC trial and 47% (6 partial responses, 1 complete response) in the FHD cohort. No immune correlates of response were identified.

CONCLUSIONS

Glasdegib demonstrated promising responses in patients with refractory scGVHD, but tolerability was limited by muscle cramping.

Novel therapies for graft versus host disease with a focus on cell therapies

Graft versus host disease (GVHD) can occur at any period post allogeneic hematopoietic stem cell transplantation as a common clinical complication contributing to significant morbidity and mortality. Acute GVHD develops in approximately 30-50% of patients receiving transplants from matched related donors. High doses of steroids are used as first-line treatment, but are unsuccessful in around 40% of patients, resulting in the diagnosis of steroid-refractory acute GVHD. Consensus has yet to develop for the management of steroid-refractory acute GVHD, and prognosis at six months has been estimated at around 50%. Thus, it is critical to find effective treatments that increase survival of steroid-refractory acute GVHD. This article describes the currently known characteristics, pathophysiology, and treatments for GVHD, with a special focus on recent advances in cell therapies. In particular, a novel cell therapy using decidua stromal cells (DSCs) was recently shown to have promising results for acute GVHD, with improved effectiveness over previous treatments including mesenchymal stromal cells. At the Karolinska Institute, severe acute GVHD patients treated with placenta-derived DSCs supplemented with either 5% albumin or 10% AB plasma displayed a one-year survival rate of 76% and 47% respectively. Furthermore, patients with steroid-refractory acute GVHD, displayed survival rates of 73% with albumin and 31% with AB plasma-supplemented DSCs, compared to the 20% survival rate in the mesenchymal stromal cell control group. Adverse events and deaths were found to be attributed only to complications of hematopoietic stem cell transplant and GVHD, not to the study intervention. ASC Therapeutics, Inc, in collaboration with the Karolinska Institute, will soon initiate a phase 2 multicenter, open-label study to further assess the efficacy and safety of intravenous DSC treatment in sixty patients with Grade II-IV steroid-refractory acute GVHD. This novel cell therapy represents a promising treatment to combat the poor prognosis that steroid-refractory acute GVHD patients currently face.

Ruxolitinib versus basiliximab for steroid-refractory acute graft-versus-host disease: a retrospective study

Acute graft-versus-host disease (aGVHD) remains a major limitation of allogeneic hematopoietic stem cell transplantation; not all patients respond to standard glucocorticoids treatment. This study retrospectively evaluated the effects of ruxolitinib compared with basiliximab for steroid-refractory aGVHD (SR-aGVHD). One hundred and twenty-nine patients were enrolled, 81 in ruxolitinib and 48 in basiliximab group. The overall response (OR) at day 28 was higher in ruxolitinib group (72.8% vs. 54.2%, P = 0.031), as with complete response (CR) (58.0% vs. 35.4%, P = 0.013). Ruxolitinib led to significantly lower 1-year cumulative incidence of chronic GVHD (cGVHD) (29.6% vs. 43.8%, P = 0.021). Besides, ruxolitinib showed higher 1-year overall survival (OS) and 1-year cumulative incidence of failure-free survival (FFS) (OS: 72.8% vs. 50.0%, P = 0.008; FFS: 58.9% vs. 39.6%, P = 0.014). The 1-year cumulative incidence of non-relapse mortality (NRM) was lower in ruxolitinib group (16.1% vs. 37.5%, P = 0.005), and the 1-year relapse was not different. The 1-year cumulative incidence of cytomegalovirus (CMV) viremia, CMV-associated diseases and Epstein-Barr virus (EBV)-associated diseases was similar between the two groups, but EBV viremia was significantly lower in ruxolitinib group (6.2% vs. 29.2%, P < 0.001). Subgroup analyses revealed that OR and survival were similar in ruxolitinib 5 mg twice daily (bid) and 10 mg bid groups. However, ruxolitinib 10 mg bid treatment markedly reduced 1-year cumulative incidence of cGVHD compared with 5 mg bid (21.1% vs. 50.0%, P = 0.016). Our study demonstrated that ruxolitinib was superior to basiliximab in SR-aGVHD treatment and cGVHD prophylaxis, therefore should be recommended.

Nestin+ Mesenchymal Stromal Cells Fibrotic Transition Mediated by CD169+ Macrophages in Bone Marrow Chronic Graft-versus-Host Disease

Chronic graft-versus-host disease (cGVHD) involves multiple organs, but little is known about bone marrow (BM) alterations caused by cGVHD. In mice and humans, we found that cGVHD is associated with BM fibrosis resulting in T cell infiltration, IgG deposition, and hematopoietic dysfunction. Macrophages and Nestin+ mesenchymal stromal cells (MSCs) participated in the process of BM fibrosis during BM cGVHD development. BM macrophage numbers were significantly increased in mice and humans with BM fibrosis associated with cGVHD. Amplified macrophages produced TGF-β1, which recruited Nestin+ MSCs forming clusters, and Nestin+ MSCs later differentiated into fibroblasts, a process mediated by increased TGF-β/Smad signaling. TLR4/MyD88-mediated activation of endoplasmic reticulum (ER) stress in macrophages is associated with fibrosis by increasing Nestin+ MSC migration and differentiation into fibroblasts. Depletion of macrophages by clodronate-containing liposomes and inhibition of ER stress by 4-phenylbutyric acid reversed BM fibrosis by inhibiting fibroblast differentiation. These studies provide insights into the pathogenesis of BM fibrosis during cGVHD development.

Mesenchymal stromal cells ameliorate chronic GVHD by boosting thymic regeneration in a CCR9-dependent manner in mice

Chronic graft-versus-host disease (cGVHD) is a major cause of morbidity and mortality after allogeneic hematopoietic stem cell transplantation. Mature donor T cells within the graft contribute to severe damage of thymic epithelial cells (TECs), which are known as key mediators in the continuum of acute GVHD (aGVHD) and cGVHD pathology. Mesenchymal stromal cells (MSCs) are reportedly effective in the prevention and treatment of cGVHD. In our previous pilot clinical trial in patients with refractory aGVHD, the incidence and severity of cGVHD were decreased, along with an increase in levels of blood signal joint T-cell receptor excision DNA circles after MSCs treatment, which indicated an improvement in thymus function of patients with GVHD, but the mechanisms leading to these effects remain unknown. Here, we show in a murine GVHD model that MSCs promoted the quantity and maturity of TECs as well as elevated the proportion of Aire-positive medullary TECs, improving both CD4+CD8+ double-positive thymocytes and thymic regulatory T cells, balancing the CD4:CD8 ratio in the blood. In addition, CCL25-CCR9 signaling axis was found to play an important role in guiding MSC homing to the thymus. These studies reveal mechanisms through which MSCs ameliorate cGVHD by boosting thymic regeneration and offer innovative strategies for improving thymus function in patients with GVHD.

Antibody-mediated pathogenesis of chronic GVHD through DBY/HLA class II complexes and induction of a GVL effect

Chronic graft-versus-host disease (cGVHD) is a multiorgan syndrome with clinical features resembling those of autoimmune diseases. Thus, understanding commonalities in the pathophysiology of cGVHD and autoimmune diseases, such as the presence of disease-risk HLA alleles, is imperative for developing novel therapies against cGVHD. Alloantibodies against H-Y antigens encoded on the Y-chromosome are well-described risk factors for cGVHD in female-to-male transplantation. However, because H-Y antigens generally localize intracellularly in the male reproductive organs, how they emerge at affected organ levels remains elusive. Here, by analyzing nationwide registry data stratified per donor-recipient sex, we identified specific HLA class II alleles that contributed to susceptibility to male cGVHD after transplantation from HLA-identical female siblings (HLA-DRB1∗15:02: hazard ratio, 1.28; 95% confidence interval, 1.03-1.58; P = .025). Coexpression of HLA-DRB1∗15:02 efficiently transported full-length H-Y antigens, especially DBY, to the surface. The presence of alloantibodies against DBY/HLA class II complexes significantly predicted the occurrence of cGVHD (68.8% vs 31.7% at 1 year; P = .002). Notably, the ability of HLA class II molecules to transport and present DBY to alloantibodies was closely associated with the susceptibility of HLA class II alleles to cGVHD. DBY specifically colocalized with HLA class II molecules on the dermal vascular endothelium in cGVHD and provoked complement-dependent cytotoxicity. Moreover, these complexes were observed in some male leukemic cells. Altogether, these findings suggest that vascular endothelial cells facilitate alloantibody-mediated cGVHD and highlight that alloantibodies against DBY/HLA class II complexes could be common targets for cGVHD and a graft-versus-leukemia effect.

ER stress: an emerging regulator in GVHD development

Allogeneic hematopoietic cell transplantation (allo-HCT) is a promising therapeutic option for hematologic malignancies. However, the clinical benefits of allo-HCT are limited by the development of complications including graft-versus-host disease (GVHD). Conditioning regimens, such as chemotherapy and irradiation, which are administered to the patients prior to allo-HCT, can disrupt the endoplasmic reticulum (ER) homeostasis, and induce ER stress in the recipient's cells. The conditioning regimen activates antigen-presenting cells (APCs), which, in turn, activate donor cells, leading to ER stress in the transplanted cells. The unfolded protein response (UPR) is an evolutionarily conserved signaling pathway that manages ER stress in response to cellular stress. UPR has been identified as a significant regulatory player that influences the function of various immune cells, including T cells, B cells, macrophages, and dendritic cells (DCs), in various disease progressions. Therefore, targeting the UPR pathway has garnered significant attention as a promising approach for the treatment of numerous diseases, such as cancer, neurodegeneration, diabetes, and inflammatory diseases. In this review, we summarize the current literature regarding the contribution of ER stress response to the development of GVHD in both hematopoietic and non-hematopoietic cells. Additionally, we explore the potential therapeutic implications of targeting UPR to enhance the effectiveness of allo-HCT for patients with hematopoietic malignancies.

Chronic graft-versus-host disease in pediatric patients: Differences and challenges

Despite the use of high-resolution molecular techniques for tissue typing, chronic graft-versus-host disease (cGVHD) remains a major complication following allogeneic hematopoietic stem cell transplant. cGVHD adversely affects the life-expectancy and quality of life. The latter is particularly important and functionally relevant in pediatric patients who have a longer life-expectancy than adults. Current laboratory evidence suggests that there is not any difference in the pathophysiology of cGVHD between adults and pediatric patients. However, there are some clinical features and complications of the disease that are different in pediatric patients. There are also challenges in the development of new therapeutics for this group of patients. In this review, we will discuss the epidemiology, pathophysiology, clinical features and consequences of the disease, and highlight the differences between pediatric and adult patients. We will examine the current treatment options for pediatric patients with moderate to severe cGVHD and discuss the challenges facing therapeutic development for cGVHD in the pediatric population.

Current perspectives on mesenchymal stromal cell therapy for graft versus host disease

Graft versus host disease (GvHD) is the clinical condition in which bone marrow-derived mesenchymal stromal cells (MSCs) have been most frequently studied. In this review, we summarize the experience from clinical trials that have paved the way to translation. While MSC-based therapy has shown an exceptional safety profile, identifying potency assays and disease biomarkers that reliably predict the capacity of a specific MSC batch to alleviate GvHD has been difficult. As GvHD diagnosis and staging are based solely on clinical criteria, individual patients recruited in the same clinical trial may have vastly different underlying biology, obscuring trial outcomes and making it difficult to determine the benefit of MSCs in subgroups of patients. An accumulating body of evidence indicates the importance of considering not only the cell product but also patient-specific biomarkers and/or immune characteristics in determining MSC responsiveness. A mode of action where intravascular MSC destruction is followed by monocyte-efferocytosis-mediated skewing of the immune repertoire in a permissive inflammatory environment would both explain why cell engraftment is irrelevant for MSC efficacy and stress the importance of biologic differences between responding and nonresponding patients. We recommend a combined analysis of clinical outcomes and both biomarkers of disease activity and MSC potency assays to identify patients with GvHD who are likely to benefit from MSC therapy.

Shared graft-versus-leukemia minor histocompatibility antigens in DISCOVeRY-BMT

T-cell responses to minor histocompatibility antigens (mHAs) mediate graft-versus-leukemia (GVL) effects and graft-versus-host disease (GVHD) in allogeneic hematopoietic cell transplantation. Therapies that boost T-cell responses improve allogeneic hematopoietic cell transplant (alloHCT) efficacy but are limited by concurrent increases in the incidence and severity of GVHD. mHAs with expression restricted to hematopoietic tissue (GVL mHAs) are attractive targets for driving GVL without causing GVHD. Prior work to identify mHAs has focused on a small set of mHAs or population-level single-nucleotide polymorphism-association studies. We report the discovery of a large set of novel GVL mHAs based on predicted immunogenicity, tissue expression, and degree of sharing among donor-recipient pairs (DRPs) in the DISCOVeRY-BMT data set of 3231 alloHCT DRPs. The total number of predicted mHAs varied by HLA allele, and the total number and number of each class of mHA significantly differed by recipient genomic ancestry group. From the pool of predicted mHAs, we identified the smallest sets of GVL mHAs needed to cover 100% of DRPs with a given HLA allele. We used mass spectrometry to search for high-population frequency mHAs for 3 common HLA alleles. We validated 24 predicted novel GVL mHAs that are found cumulatively within 98.8%, 60.7%, and 78.9% of DRPs within DISCOVeRY-BMT that express HLA-A∗02:01, HLA-B∗35:01, and HLA-C∗07:02, respectively. We confirmed the immunogenicity of an example novel mHA via T-cell coculture with peptide-pulsed dendritic cells. This work demonstrates that the identification of shared mHAs is a feasible and promising technique for expanding mHA-targeting immunotherapeutics.

The Role of Extracellular Vesicles (EVs) in Chronic Graft vs. Host Disease, and the Potential Function of Placental Cell-Derived EVs as a Therapeutic Tool

Chronic graft-versus-host disease (cGVHD) presents with dermal inflammation and fibrosis. We investigated the characteristics of extracellular vesicles (EVs) obtained from cGVHD patients, and their potential effects on human dermal fibroblast (NHDF) cells. The anti-inflammatory and anti-fibrotic effects of placental EVs were also explored given their known anti-inflammatory properties. Fourteen cGVHD patients' EVs contained higher levels of fibrosis-related proteins, TGFβ and α-smooth muscle actin (αSMA), compared to EVs from thirteen healthy subjects. The exposure of NHDF cells to the patients' EVs increased the NHDF cells' TGFβ and αSMA expressions. Placental EVs derived from placental-expanded cells (PLX) (Pluri Inc.) and human villous trophoblast (HVT) cells expressing the mesenchymal markers CD29, CD73, and CD105, penetrated into both the epidermal keratinocytes (HACATs) and NHDF cells. Stimulation of the HACAT cells with cytokine TNFα/INFγ (0.01-0.1 ng/µL) reduced cell proliferation, while the addition of placental EVs attenuated this effect, increasing and normalizing cell proliferation. The treatment of NHDF cells with a combination of TGFβ and placental HVT EVs reduced the stimulatory effects of TGFβ on αSMA production by over 40% (p = 0.0286). In summary, EVs from patients with cGVHD can serve as a biomarker for the cGVHD state. Placental EVs may be used to regulate dermal inflammation and fibrosis, warranting further investigation of their therapeutic potential.

Axatilimab for Chronic Graft-Versus-Host Disease After Failure of at Least Two Prior Systemic Therapies: Results of a Phase I/II Study

PURPOSE

Chronic graft-versus-host disease (cGVHD) remains the major cause of late morbidity after allogeneic hematopoietic cell transplantation. Colony-stimulating factor 1 receptor (CSF-1R)-dependent macrophages promote cGVHD fibrosis, and their elimination in preclinical studies ameliorated cGVHD. Axatilimab is a humanized monoclonal antibody that inhibits CSF-1R signaling and restrains macrophage development.

PATIENTS AND METHODS

This phase I (phI)/phase II (phII) open-label study (ClinicalTrials.gov identifier: NCT03604692) evaluated safety, tolerability, and efficacy of axatilimab in patients age ≥ 6 years with active cGVHD after ≥ 2 prior systemic therapy lines. Primary objectives in phI were to identify the optimal biologic and recommended phII dose and in phII to evaluate the overall (complete and partial) response rate (ORR) at the start of treatment cycle 7.

RESULTS

Forty enrolled patients (17 phI; 23 phII) received at least one axatilimab dose. In phI, a dose of 3 mg/kg given once every 4 weeks met the optimal biologic dose definition. Two dose-limiting toxicities occurred at the 3 mg/kg dose given once every 2 weeks. At least one treatment-related adverse event (TRAE) was observed in 30 patients with grade ≥ 3 TRAEs in eight patients, the majority known on-target effects of CSF-1R inhibition. No cytomegalovirus reactivations occurred. With the 50% ORR at cycle 7 day 1, the phII cohort met the primary efficacy end point. Furthermore, the ORR in the first six cycles, an end point supporting regulatory approvals, was 82%. Responses were seen in all affected organs regardless of prior therapy. Fifty-eight percent of patients reported significant improvement in cGVHD-related symptoms using the Lee Symptom Scale. On-target activity of axatilimab was suggested by the decrease in skin CSF-1R-expressing macrophages.

CONCLUSION

Targeting profibrotic macrophages with axatilimab is a therapeutically promising novel strategy with a favorable safety profile for refractory cGVHD.

Day 4 collection of granulocyte colony-stimulating factor-mobilized HLA-matched sibling donor peripheral blood allografts demonstrates no long-term increase in chronic graft-versus-host disease or relapse rates

BACKGROUND AIMS

In a previous pilot study of HLA-matched sibling donor hematopoietic cell transplantation (HCT), the authors determined the feasibility of day 4 versus day 5 granulocyte colony-stimulating factor (G-CSF)-mobilized peripheral blood stem cell (PBSC) collection compared with a historical cohort. Given identified differences in the PBSC product (day 4 cohort with significantly lower infused total nucleated, mononuclear and CD3 cells compared with other collection cohorts), the authors performed a follow-up study to determine long-term post-HCT outcomes, including detailed characterization of chronic graft-versus-host disease (GVHD).

METHODS

This was a prospective observational study, and the authors collected data on chronic GVHD, staging, sites of involvement and treatments. Performance status, incidence of relapse, overall survival and duration of immunosuppressive therapy (IST) were also evaluated. Data were examined retrospectively. To account for differences in length of follow-up among cohorts, the authors also determined performance status and chronic GVHD staging, sites and treatment at 2 years post-HCT.

RESULTS

At 2 years post-HCT, the overall survival rate was 71.7% in the day 4 cohort compared with 61.5%, 52% and 56% in the day 5, 2-day and historical cohorts, respectively (P = 0.283). The cumulative incidence of chronic GVHD was 65.2% in the day 4 cohort versus 46.4% in the day 5 cohort, 51.1% in the 2-day cohort and 65% in the historical cohort (P = 0.26). There was no significant difference in the maximum overall stage of chronic GVHD (P = 0.513), median number of sites involved (P = 0.401) or cumulative incidence of discontinuation of IST (P = 0.32). Death from chronic GVHD was less common in the day 4 and day 5 cohorts compared with the 2-day and historical cohorts, though this did not reach statistical significance.

CONCLUSIONS

The authors' preliminary results demonstrated that collection of allogeneic matched sibling donor PBSCs on day 4 of G-CSF was feasible, reduced donor exposure to growth factor and was associated with an initial cost savings. Importantly, the authors now demonstrate that transplantation of day 4 mobilized PBSCs is not associated with any adverse outcomes post-HCT, including late effects such as chronic GVHD. Further investigation of donor G-CSF collection algorithms is merited in other HCT settings, including unrelated and mismatched related donors.

Targeting Bcl-6 prevents sclerodermatous chronic graft-versus-host disease by abrogating T follicular helper differentiation in mice

BACKGROUND

Chronic graft-versus-host disease (cGVHD) is the most common cause of non-relapse mortality (NRM) after allogeneic hematopoietic stem cell transplantation (allo-HSCT). CD4⁺ follicular helper T (Tfh) cells, specialized providers of T cell help to B cells, play a vital role in GVHD pathogenesis. B-cell lymphoma-6 (Bcl-6) transcription factor has been shown to be required for Tfh-mediated germinal center reactions. In this study, we would like to evaluate the effect of Bcl-6 on Tfh function in sclerodermatous cGVHD and the efficacy of Bcl-6 inhibitors (Bcl-6i) for treating a minor histocompatibility complex (miHC) mismatch model of sclerodermatous cGVHD (scl-cGVHD).

METHODS

A minor histocompatibility haploidentical model of scl-cGVHD was established and received intraperitoneal injection of 79-6, a small-molecule inhibitor of Bcl-6. The clinical manifestations and survival times of cGVHD mice were recorded. The histological assessment was performed by hematoxylin-eosin (HE) and Masson's trichrome staining on the skin and lung tissues. Tfh cells and germinal center B cells in the spleen and peripheral blood were detected by flow cytometry. The cellular markers were immunostained in different organs. ELISA was performed to detect cytokine secretion.

RESULTS

Bcl-6 inhibition by 79-6 improved the clinical manifestation of scl-cGVHD mice and prolonged their survival. The histopathologic damage, particular the fibrotic changes of scl-cGVHD mice was significantly relieved after 79-6 treatment. Furthermore, 79-6 treatment not only suppressed the development and function of Tfh and Tph cells in the peripheral blood, but also reduced the survival of Tfh cells in the spleen. Moreover, 79-6 decreased the frequency of GC plasmocytes accompanied by a reduction in IL-21.

CONCLUSIONS

Our study demonstrates that Bcl-6 inhibitor could prevent murine sclerodermatous chronic graft-versus-host disease by abrogating T follicular helper differentiation and suppressing the function of GC B cells, indicating that Bcl-6 inhibition may be a potential treatment for patients with cGVHD.

Blocking common γ chain cytokine signaling ameliorates T cell-mediated pathogenesis in disease models

The common γ chain (γc; IL-2RG) is a subunit of the interleukin (IL) receptors for the γc cytokines IL-2, IL-4, IL-7, IL-9, IL-15, and IL-21. The lack of appropriate neutralizing antibodies recognizing IL-2RG has made it difficult to thoroughly interrogate the role of γc cytokines in inflammatory and autoimmune disease settings. Here, we generated a γc cytokine receptor antibody, REGN7257, to determine whether γc cytokines might be targeted for T cell-mediated disease prevention and treatment. Biochemical, structural, and in vitro analysis showed that REGN7257 binds with high affinity to IL-2RG and potently blocks signaling of all γc cytokines. In nonhuman primates, REGN7257 efficiently suppressed T cells without affecting granulocytes, platelets, or red blood cells. Using REGN7257, we showed that γc cytokines drive T cell-mediated disease in mouse models of graft-versus-host disease (GVHD) and multiple sclerosis by affecting multiple aspects of the pathogenic response. We found that our xenogeneic GVHD mouse model recapitulates hallmarks of acute and chronic GVHD, with T cell expansion/infiltration into tissues and liver fibrosis, as well as hallmarks of immune aplastic anemia, with bone marrow aplasia and peripheral cytopenia. Our findings indicate that γc cytokines contribute to GVHD and aplastic anemia pathology by promoting these characteristic features. By demonstrating that broad inhibition of γc cytokine signaling with REGN7257 protects from immune-mediated disorders, our data provide evidence of γc cytokines as key drivers of pathogenic T cell responses, offering a potential strategy for the management of T cell-mediated diseases.

Partially replacing cyclophosphamide with bendamustine in combination with cyclosporine A improves survival and reduces xenogeneic graft-versus-host-disease

Introduction

The use of allogeneic hematopoietic cell transplantation (allo-HCT) for treating hematological disorders is increasing, but the development of graft-versus-host disease (GvHD) remains a major cause of morbidity and mortality. The use of post-transplant cyclophosphamide (CY) has significantly improved outcomes following allo-HCT, but complications of viral reactivation due to delayed immune reconstitution or relapse remain. Other laboratories are evaluating the potential benefit of lowering the dose of CY given post-transplant, whereas our laboratory has been focusing on whether partially replacing CY with another DNA alkylating agent, bendamustine (BEN) may be advantageous in improving outcomes with allo-HCT.

Methods

Here, we utilized a xenogeneic GvHD (xGvHD) model in which immunodeficient NSG mice are infused with human peripheral blood mononuclear cells (PBMCs).

Results

We show that a lower dose of CY (25 mg/kg) given on days +3 and +4 or CY (75 mg/kg) given on only day +3 post-PBMC infusion is not sufficient for improving survival from xGvHD, but can be improved with the addition of BEN (15 mg/kg) on day +4 to day +3 CY (75 mg/kg). CY/BEN treated mice when combined with cyclosporine A (CSA) (10mg/kg daily from days +5 to +18 and thrice weekly thereafter), had improved outcomes over CY/CY +CSA treated mice. Infiltration of GvHD target organs was reduced in both CY/CY and CY/BEN treatment groups versus those receiving no treatment. CY/CY +CSA mice exhibited more severe xGvHD at day 10, marked by decreased serum albumin and increased intestinal permeability. CY/BEN treated mice had reductions in naïve, effector memory and Th17 polarized T cells. RNAseq analysis of splenocytes isolated from CY/CY and CY/BEN treated animals revealed increased gene set enrichment in multiple KEGG pathways related to cell migration, proliferation/differentiation, and inflammatory pathways, among others with CY/BEN treatment.

Conclusion

Together, we illustrate that the use of CY/BEN is safe and shows similar control of xGvHD to CY/CY, but when combined with CSA, survival with CY/BEN is significantly prolonged compared to CY/CY.

Thymic stromal lymphopoietin levels after allogeneic hematopoietic stem cell transplantation

BACKGROUND

Thymic stromal lymphopoietin (TSLP) is an immunoregulatory, Th2-polarizing cytokine produced by epithelial cells. We hypothesized that TSLP affects immune reconstitution after hematopoietic stem cell transplantation (HSCT) leading to increased alloreactivity.

METHODS

We measured plasma TSLP by ELISA in 38 patients and assessed the immune reconstitution by flow cytometry.

RESULTS

TSLP levels rose after initiation of the conditioning to peak at day +21 after HSCT (p = .03), where TSLP levels correlated with counts of neutrophils (rho = 0.36, p = .04), monocytes (rho = 0.58, p = .006), and lymphocytes (rho = 0.59, p = .02). Overall absolute TSLP levels were not associated with acute or chronic graft-vs-host disease (a/cGvHD). However, patients mounting a sustained increase in TSLP levels at day +90 had a higher risk of cGvHD compared to patients who had returned to pre-conditioning levels at that stage (cumulative incidence: 77% vs. 38%, p = .01).

CONCLUSION

In conclusion, this study suggests a role of TSLP in immune reconstitution and alloreactivity post-HSCT. lymphopoietin (TSLP) is an immunoregulatory, Th2-polarizing cytokine produced by epithelial cells. We hypothesized that TSLP affects immune reconstitution after hematopoietic stem cell transplantation (HSCT) leading to increased alloreactivity. We measured plasma TSLP by ELISA in 38 patients and assessed the immune reconstitution by flow cytometry.

Immune-Related Toxicity Among Adolescent and Young Adult with Melanoma as Compared with the Elderly

Background: Melanoma constitutes ∼8% of malignancies diagnosed among adolescents and young adults (AYA). Although immunotherapy with checkpoint inhibitor (ICI) has become a standard treatment for melanoma, available data on immune-related adverse events (irAE) among AYA population are still limited. Some early reports suggested that irAE may be more frequent among AYA than other age groups. Methods: We performed a retrospective cohort study of melanoma patients who were previously ICI naive and received ICI at our institution during 2007-2019, comparing the incidences of irAE between AYA and elderly patients. AYA cohort was defined as age 15-39 years and elderly cohort was defined as age >65 years at ICI initiation. Results: Analyses included 153 patients: 48 AYA and 105 elderly. The median age was 31.2 and 72.0 years, respectively. The AYA cohort had better performance status and fewer comorbidities than the elderly cohort. A combined ICI regimen, ipilimumab plus nivolumab, was used more frequently among the AYA than the elderly cohort: 25.0% versus 3.8%, p < 0.001. In univariable analyses, AYA experienced more increased liver enzymes, more hospitalization, but less skin rash. After adjusting for baseline characteristics and treatment regimen in multivariable analyses, AYA was independently associated with a lower incidence of skin rash: odds ratio 0.36 (95% confidence interval: 0.14-0.75), p = 0.006. Conclusion: In this large cohort of melanoma patients undergoing first-line immunotherapy, skin rash was less frequent among AYA than the elderly. Although some toxicities may appear more prevalent among AYA, this was attributable to the higher use of combined ICI regimen.

Extracorporeal photopheresis for the treatment of chronic graft versus host disease

OBJECTIVES

Chronic graft versus host disease (chronic GVHD) still remains the leading cause of late morbidity and mortality for allogeneic hematopoietic stem cell transplant (allo-HSCT) recipients. In this retrospective study, 53 consecutive allo-HSCT patients with chronic GVHD refractory to corticosteroids were treated with extracorporeal photopheresis (ECP).

METHODS

This study was performed as a retrospective single-center study. Medical records of a total of 59 patients treated with ECP for chronic GVHD were reviewed.

RESULTS

Best organ responses to ECP were observed in skin, mouth mucosa, eyes and liver. Overall response rate (ORR) to ECP was 81.2% (CR 17% and PR 64.2%). Overall survival (OS) was 84.9% and 36.7%, at 1 and 3 years, respectively. Female sex appears to have an advantage on ORR. Patients achieving ORR were able to maintain their responses with a prolonged continuation of treatments for +6 and +12 months indicating the benefits of longer ECP treatment.

DISCUSSION

We found that patients with chronic GVHD who were treated with ECP for 12 months or longer had a higher response rate. Our findings in line with the data reported previously suggest that patients responding to ECP should continue longer therapy schedules to achieve a better and sustained response. In our cohort, long-term ECP therapy was safe and well-tolerated with no significant adverse effects. Best responses were observed in the patients with skin, eye, liver and oral involvement. The ECP procedure offers the advantage relative to the problems with typical immunosuppressive agents. The female sex appeared to have an advantage based on the cumulative probability of the OR after ECP for chronic GVHD.

Ageing-resembling phenotype of long-term allogeneic hematopoietic cells recipients compared to their donors

BACKGROUND

Ageing is a complex phenomenon that leads to decreased proliferative activity, loss of function of the cells, and cellular senescence. Senescence of the immune system exacerbates individual's immune response, both humoral and cellular but increases the frequency of infections. We hypothesized that physiological ageing of adaptive immune system occurs in recipients of allogeneic hematopoietic cells transplant (allo-HCT) at faster rate when compared to their respective donors since the small number of donor cells undergo immense proliferative stress restoring recipients hematopoiesis. We compared molecular characterizations of ageing between recipients and donors of allo-HCT: telomeric length and immunophenotypic changes in main lymphocyte subsets - CD4⁺, CD8⁺, CD19⁺, CD56⁺.

RESULTS

Median telomeric length (TL) of CD8⁺ lymphocytes was significantly longer in donors compared to recipients (on average 2,1 kb and 1,7 kb respectively, p = 0,02). Similar trends were observed for CD4⁺ and CD19⁺ although the results did not reach statistical significance. We have also found trends in the immunophenotype between recipients and donors in the subpopulations of CD4⁺ (naïve and effector memory), CD8⁺ Eomes⁺ and B-lymphocytes (B1 and B2). Lower infection risk recipients had also a significantly greater percentage of NK cells (22,3%) than high-risk patients (9,3%) p = 0,04.

CONCLUSION

Our data do not support the initial hypothesis of accelerated aging in the long term all-HCT recipients with the exception of the recipients lymphocytes (mainly CD8⁺) which present some molecular features, characteristic for physiological ageing (telomeric shortening, immunophenotype) when compared to their respective donors. However, a history of lower infection numbers in HCT recipients seems to be associated with increased percentage of NK cells. The history of GVHD seems not to affect the rate of ageing. Therefore, it is safe to conclude that the observed subtle differences between recipients' and donors' cells result mainly from the proliferative stress in the early period after allo-HCT and the difference between hosts' and recipients' microenvironments.

Novel and Promising Strategies for Therapy of Post-Transplant Chronic GVHD

Despite the achievements that have increased viability after the transplantation of allogeneic hematopoietic stem cells (aHSCT), chronic graft-versus-host disease (cGVHD) remains the main cause of late complications and post-transplant deaths. At the moment, therapy alternatives demonstrate limited effectiveness in steroid-refractory illness; in addition, we have no reliable data on the mechanism of this condition. The lack of drugs of choice for the treatment of GVHD underscores the significance of the design of new therapies. Improved understanding of the mechanism of chronic GVHD has secured new therapy goals, and organized diagnostic recommendations and the development of medical tests have ensured a general language and routes for studies in this field. These factors, combined with the rapid development of pharmacology, have helped speed up the search of medicines and medical studies regarding chronic GVHD. At present, we can hope for success in curing this formidable complication. This review summarizes the latest clinical developments in new treatments for chronic GVHD.

IL-39 promotes chronic graft-versus-host disease by increasing T and B Cell pathogenicity

BACKGROUND

Chronic graft-versus-host disease (cGVHD) remains a major complication during the late phase of allogeneic hematopoietic stem cell transplantation (allo-HSCT). IL-39, a newly described pro-inflammatory cytokine belonging to the IL-12 family, plays a role in lupus development. Recently, IL-39 has been identified as a pathogenic factor in acute GVHD (aGVHD). However, the role of IL-39 in the pathogenesis of cGVHD remains unclear.

METHODS

We constructed a recombinant IL-39 plasmid and established scleroderma and lupus-like cGVHD models. Quantitative PCR and enzyme-linked immunosorbent assay (ELISA) were used to detect IL-39 expression in mice and patients post transplantation, respectively. Hydrodynamic gene transfer (HGT) was performed to achieve IL-39 overexpression in vivo. Multiparameter flow cytometry, western blotting, and assays in vitro were performed to investigate the effect of IL-39 on cGVHD.

RESULTS

The relative expression of IL-23p19 and EBi3 was significantly increased in the intestine of cGVHD mice on day 40 post allo-HSCT, and IL-39 levels were significantly elevated in the serum of patients following allo-HSCT. Overexpression of IL-39 significantly aggravated the severity of cGVHD. Increased IL-39 levels promoted T-cell activation and germinal center responses, and may exacerbate thymic damage. Consistently, blocking IL-39 markedly ameliorated immune dysregulation in the cGVHD mice. Furthermore, we found that IL-39 was produced by B cells, CD11b⁺ cells, and CD8⁺T cells after activation. Stimulation of IL-39 led to upregulation of the IL-39 receptor on CD4⁺T cells and further caused activation of the STAT1/STAT3 pathway, through which IL-39 may exert its pro-inflammatory effects.

CONCLUSION

Our study reveals a critical role for IL-39 in cGVHD pathogenesis and indicates that IL-39 may serve as a potential therapeutic target for cGVHD prevention.

MicroRNA-31 regulates T-cell metabolism via HIF1α and promotes chronic GVHD pathogenesis in mice

Chronic graft-versus-host disease (cGVHD) remains a major obstacle impeding successful allogeneic hematopoietic cell transplantation (HCT). MicroRNAs (miRs) play key roles in immune regulation during acute GVHD development. Preclinical studies to identify miRs that affect cGVHD pathogenesis are required to develop these as potential lifesaving interventions. Using oligonucleotide array, we identified miR-31, which was significantly elevated in allogeneic T cells after HCT in mice. Using genetic and pharmacologic approaches, we demonstrated a key role for miR-31 in mediating donor T-cell pathogenicity in cGVHD. Recipients of miR-31-deficient T cells displayed improved cutaneous and pulmonary cGVHD. Deficiency of miR-31 reduced T-cell expansion and T helper 17 (Th17) cell differentiation but increased generation and function of regulatory T cells (Tregs). MiR-31 facilitated neuropilin-1 downregulation, Foxp3 loss, and interferon-γ production in alloantigen-induced Tregs. Mechanistically, miR-31 was required for hypoxia-inducible factor 1α (HIF1α) upregulation in allogeneic T cells. Therefore, miR-31-deficient CD4 T cells displayed impaired activation, survival, Th17 cell differentiation, and glycolytic metabolism under hypoxia. Upregulation of factor-inhibiting HIF1, a direct target of miR-31, in miR-31-deficient T cells was essential for attenuating T-cell pathogenicity. However, miR-31-deficient CD8 T cells maintained intact glucose metabolism, cytolytic activity, and graft-versus-leukemia response. Importantly, systemic administration of a specific inhibitor of miR-31 effectively reduced donor T-cell expansion, improved Treg generation, and attenuated cGVHD. Taken together, miR-31 is a key driver for T-cell pathogenicity in cGVHD but not for antileukemia activity. MiR-31 is essential in driving cGVHD pathogenesis and represents a novel potential therapeutic target for controlling cGVHD.

Autoimmune diseases after allogeneic stem cell transplantation: a clinician's guide and future outlook

INTRODUCTION

Autoimmune disease (AD) may occur after allogeneic hematopoietic stem cell transplantation (HSCT). The autoimmune mechanism seems to be related to an imbalance of the immune regulation effect of T-regulatory lymphocytes on autoreactive T-lymphocytes.

AREAS COVERED

ADs include hematological ADs (HADs) and nonhematologic ADs (NHADs) involving organs such as thyroid, peripheral and central nervous system, skin, liver, connective tissue, gastrointestinal tract, and kidney. To identify the risk factors for ADs, to report their clinical characteristics, and to discuss new approaches represent the areas covered in this review.

EXPERT OPINION

Some risk factors for HAD and NHAD are common and include nonmalignant diseases, young age, cord blood as a stem cell source, conditioning regimens without total body irradiation, alemtuzumab, antithymocyte globulin, T-cell-depleted transplant, some viral infection, mixed chimerism, and chronic Graft versus Host Disease. In NHADs, the detection of autoantibodies is more frequent and the transfer of autoimmunity from the donor to the recipient represents the pathogenetic mechanism responsible for these complications. New therapeutic approaches such as bortezomib, daratumumab, sirolimus, eculizumab, and eltrombopag appear to be promising in terms of better efficacy and reduced toxicity compared to traditional therapies. New horizons based on personalized therapies will allow us to improve the prognosis of AD.

Effect of Vitamin D on Graft-versus-Host Disease

The different cell subsets of the immune system express the vitamin D receptor (VDR). Through the VDR, vitamin D exerts different functions that influence immune responses, as previously shown in different preclinical models. Based on this background, retrospective studies explored the impacts of vitamin D levels on the outcomes of patients undergoing allogeneic hematopoietic stem-cell transplantation, showing that vitamin D deficiency is related to an increased risk of complications, especially graft-versus-host disease. These results were confirmed in a prospective cohort trial, although further studies are required to confirm this data. In addition, the role of vitamin D on the treatment of hematologic malignancies was also explored. Considering this dual effect on both the immune systems and tumor cells of patients with hematologic malignancies, vitamin D might be useful in this setting to decrease both graft-versus-host disease and relapse rates.

SGK1, a Critical Regulator of Immune Modulation and Fibrosis and a Potential Therapeutic Target in Chronic Graft-Versus-Host Disease

Patients with severe chronic graft-versus-host disease (cGVHD) always experience debilitating tissue injury and have poorer quality of life and shorter survival time. The early stage of cGVHD is characterized by inflammation, which eventually leads to extensive tissue fibrosis in various organs, such as skin and lung, eventually inducing scleroderma-like changes and bronchiolitis obliterans syndrome. Here we review the functions of serum/glucocorticoid regulated kinase 1 (SGK1), a hub molecule in multiple signal transduction pathways and cell phosphorylation cascades, which has important roles in cell proliferation and ion channel regulation, and its relevance in cGVHD. SGK1 phosphorylates the ubiquitin ligase, NEDD4, and induces Th cells to differentiate into Th17 and Th2 phenotypes, hinders Treg development, and promotes inflammatory fibrosis. Phosphorylation of NEDD4 by SGK1 also leads to up-regulation of the transcription factor SMAD2/3, thereby amplifying the fibrosis-promoting effect of TGF-β. SGK1 also up-regulates the inflammatory transcription factor, nuclear factor-κB (NF-κB), which in turn stimulates the expression of multiple inflammatory mediators, including connective tissue growth factor. Overexpression of SGK1 has been observed in various fibrotic diseases, including pulmonary fibrosis, diabetic renal fibrosis, liver cirrhosis, hypertensive cardiac fibrosis, peritoneal fibrosis, and Crohn’s disease. In addition, SGK1 inhibitors can attenuate, or even reverse, the effect of fibrosis, and may be used to treat inflammatory conditions and/or fibrotic diseases, such as cGVHD, in the future.

Modeling acute graft-versus-host disease (aGVHD) in murine bone marrow transplantation (BMT) models with MHC disparity

For more than 50years, hematopoietic stem cell transplantation (HSCT) has been the major curative therapy for hematological malignancies and genetic disorders, but its success is limited by the development of graft-versus-host disease (GVHD). GVHD represents a post-transplantation disorder representing the immune-mediated attack of transplant-derived T cells against recipient tissue finally leading to increased morbidity and mortality of the recipient. GVHD develops if donor and recipient are disparate in major or minor histocompatibility antigens (MHC, miHA). Most of the initial knowledge about the biology of GVHD is derived from murine bone marrow transplantation (BMT) models. Of course, GVHD mouse models do not reflect one to one the human situation, but they contribute significantly to our understanding how conditioning and danger signals activate the immune system, enlighten the role of individual molecules, e.g., cytokines, chemokines, death-inducing ligands, define the function of lymphocytes subpopulations for GVHD development and have significant impact on establishing new treatment and prevention strategies used in clinical HSCT. This chapter describes in detail the procedure of allogeneic BMT and the development of GVHD in two commonly used allogeneic murine BMT models (B6→B6.bm1, B6→B6D2F1) with different MHC disparities, which can be used as a basis for advanced studies of GVHD pathology or the development of new treatment strategies.

Targeting the Retinoid X Receptor Pathway Prevents and Ameliorates Murine Chronic Graft-Versus-Host Disease

Most allogeneic hematopoietic stem cell transplant (allo-HSCT) recipients receive peripheral blood stem cell grafts resulting in a 30%-70% incidence of chronic graft-versus-host disease (cGVHD), a major cause of mortality and morbidity in long-term survivors. While systemic steroids remain the standard of care for first-line therapy, patients may require long-term administration, and those with steroid-resistant or refractory cGVHD have a worse prognosis. Although durable and deep responses with second-line therapies can be achieved in some patients, there remains an urgent need for new therapies. In this study, we evaluated the efficacy of IRX4204, a novel agonist that activates RXRs and is in clinical trials for cancer treatment to prevent and treat cGVHD in two complementary murine models. In a major histocompatibility complex mismatched, non-sclerodermatous multiorgan system model with bronchiolitis obliterans, IRX4204 prevented and reversed cGVHD including associated pulmonary dysfunction with restoration of germinal center T-follicular helper: T-follicular regulatory cell balance. In a minor histocompatibility antigen disparate sclerodermatous model, IRX4204 treatment significantly prevented and ameliorated skin cGVHD by reducing Th1 and Th17 differentiation due to anti-inflammatory properties. Together, these results indicate that IRX4204 is a promising therapeutic option to treat cGVHD with bronchiolitis obliterans or sclerodermatous manifestations.

Donor bone marrow-derived macrophage MHC II drives neuroinflammation and altered behavior during chronic GVHD in mice

Graft-versus-host disease (GVHD) remains the leading cause of nonrelapse mortality after allogeneic stem cell transplantation for hematological malignancies. Manifestations of GVHD in the central nervous system (CNS) present as neurocognitive dysfunction in up to 60% of patients; however, the mechanisms driving chronic GVHD (cGVHD) in the CNS are yet to be elucidated. Our studies of murine cGVHD revealed behavioral deficits associated with broad neuroinflammation and persistent Ifng upregulation. By flow cytometry, we observed a proportional shift in the donor-derived T-cell population in the cGVHD brain from early CD8 dominance to later CD4 sequestration. RNA sequencing of the hippocampus identified perturbations to structural and functional synapse-related gene expression, together with the upregulation of genes associated with interferon-γ responses and antigen presentation. Neuroinflammation in the cortex of mice and humans during acute GVHD was recently shown to be mediated by resident microglia-derived tumor necrosis factor. In contrast, infiltration of proinflammatory major histocompatibility complex (MHC) class II+ donor bone marrow (BM)-derived macrophages (BMDMs) was identified as a distinguishing feature of CNS cGVHD. Donor BMDMs, which composed up to 50% of the CNS myeloid population, exhibited a transcriptional signature distinct from resident microglia. Recipients of MHC class II knockout BM grafts exhibited attenuated neuroinflammation and behavior comparable to controls, suggestive of a critical role of donor BMDM MHC class II expression in CNS cGVHD. Our identification of disease mediators distinct from those in the acute phase indicates the necessity to pursue alternative therapeutic targets for late-stage neurological manifestations.

Phase 1 Studies to Evaluate the Food Effect and Relative Bioavailability of Tablet and Capsule Formulations of Belumosudil in Healthy Adult Subjects

Belumosudil is a selective Rho-associated coiled-coil containing protein kinase 2 inhibitor. A capsule formulation was used during early clinical development of belumosudil; it was later replaced by a tablet formulation, which mimicked the capsule's release properties and facilitated manufacturing scalability. To assess belumosudil's pharmacokinetics, including potential food effects, and evaluate the relative bioavailability of the 2 formulations, 2 phase 1 clinical trials were conducted. Administration of both belumosudil tablets and capsules with food increased exposure ≈2× as compared to the fasted state and delayed time to maximum concentration by 0.5 hour, indicating a decrease in the rate but increase in the extent of absorption with fed administration. Relative bioavailability was slightly higher when belumosudil was administered as tablets vs capsules, although the difference was not clinically meaningful. Safety and tolerability were generally consistent with the known safety profile of belumosudil. The results of these studies support administration of belumosudil with food.

A Phase 1 Pharmacokinetic Drug Interaction Study of Belumosudil Coadministered With CYP3A4 Inhibitors and Inducers and Proton Pump Inhibitors

Belumosudil is a selective Rho-associated protein kinase 2 inhibitor. Inhibition of Rho-associated protein kinase 2 has emerged as a promising treatment for chronic graft-versus-host disease by restoring immune homeostasis and reducing fibrosis. In vitro assessments have suggested that metabolism of belumosudil is primarily dependent on cytochrome P450 (CYP) 3A4 activity and that the solubility of belumosudil is pH dependent. As such, this 2-part clinical drug-drug interaction study was conducted to assess the effect of itraconazole (a strong CYP3A4 inhibitor), rifampicin (a strong CYP3A4 inducer), rabeprazole, and omeprazole (both proton pump inhibitors) on the pharmacokinetics of belumosudil. No clinically relevant change in belumosudil exposure was observed following a 200-mg single oral dose of belumosudil with itraconazole; however, exposure of main metabolite, KD025m2, was decreased. Consistent with the proposed metabolic pathway of belumosudil, the strong CYP3A4 inducer rifampicin significantly decreased exposure of belumosudil and KD025m2 and increased KD025m1 exposure. When a 200-mg single oral dose of belumosudil was coadministered with both rabeprazole and omeprazole, parent and metabolite exposures were largely reduced, suggesting that belumosudil dosage should be increased when given with PPIs. Administration of belumosudil with and without perpetrator drugs was safe, and no notable adverse events were reported.