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Chronic graft-versus-host disease (cGvHD) remains a prominent barrier to allogeneic hematopoietic stem cell transplantion as the leading cause of nonrelapse mortality and significant morbidity. Tremendous progress has been achieved in both the understanding of pathophysiology and the development of new therapies for cGvHD. Although our field has historically approached treatment from an empiric position, research performed at the bedside and bench has elucidated some of the complex pathophysiology of cGvHD. From the clinical perspective, there is significant variability of disease manifestations between individual patients, pointing to diverse biological underpinnings. Capitalizing on progress made to date, the field is now focused on establishing personalized approaches to treatment. The intent of this article is to concisely review recent knowledge gained and formulate a path toward patient-specific cGvHD therapy.

IMPORTANCE: Prior studies have demonstrated an association between cutaneous chronic graft-vs-host disease (cGVHD) and mortality. Assessment of the prognostic value of different measures of disease severity would assist in risk stratification. OBJECTIVE: To compare the prognostic value of body surface area (BSA) and National Institutes of Health (NIH) Skin Score on survival outcomes stratified by erythema and sclerosis subtypes of cGVHD. DESIGN, SETTING, AND PARTICIPANTS: Multicenter prospective cohort study from the Chronic Graft-vs-Host Disease Consortium including 9 medical centers in the US, enrolled from 2007 through 2012 and followed until 2018. Participants were adults and children with a diagnosis of cGVHD requiring systemic immunosuppression and with skin involvement during the study period, who had longitudinal follow-up. Data analysis was performed from April 2019 to April 2022. EXPOSURES: Patients underwent continuous BSA estimation and categorical NIH Skin Score grading of cutaneous cGVHD at enrollment and every 3 to 6 months thereafter. MAIN OUTCOMES AND MEASURES: Nonrelapse mortality (NRM) and overall survival (OS), compared between BSA and NIH Skin Score longitudinal prognostic models, adjusted for age, race, conditioning intensity, patient sex, and donor sex. RESULTS: Of 469 patients with cGVHD, 267 (57%) (105 female [39%]; mean [SD] age, 51 [12] years) had cutaneous cGVHD at enrollment, and 89 (19%) developed skin involvement subsequently. Erythema-type disease had earlier onset and was more responsive to treatment compared with sclerosis-type disease. Most cases (77 of 112 [69%]) of sclerotic disease occurred without prior erythema. Erythema-type cGVHD at first follow-up visit was associated with NRM (hazard ratio, 1.33 per 10% BSA increase; 95% CI, 1.19-1.48; P < .001) and OS (hazard ratio, 1.28 per 10% BSA increase; 95% CI, 1.14-1.44; P < .001), while sclerosis-type cGVHD had no significant association with mortality. The model with erythema BSA collected at baseline and first follow-up visits retained 75% of the total prognostic information (from all covariates including BSA and NIH Skin Score) for NRM and 73% for OS, with no statistical difference between prognostic models (likelihood ratio test χ2, 5.9; P = .05). Conversely, NIH Skin Score collected at the same intervals lost significant prognostic information (likelihood ratio test χ2, 14.7; P < .001). The model incorporating NIH Skin Score instead of erythema BSA accounted for only 38% of the total information for NRM and 58% for OS. CONCLUSIONS AND RELEVANCE: In this prospective cohort study, erythema-type cutaneous cGVHD was associated with increased risk of mortality. Erythema BSA collected at baseline and follow-up predicted survival more accurately than the NIH Skin Score in patients requiring immunosuppression. Accurate assessment of erythema BSA may assist in identifying patients with cutaneous cGVHD at high risk for mortality.

Letermovir is a relatively new antiviral for prophylaxis against cytomegalovirus (CMV) after allogeneic hematopoietic cell transplantation (HCT). CMV-seropositive HCT recipients who received letermovir prophylaxis from 2018 to 2020 at our center were evaluated for letermovir resistance and breakthrough CMV reactivation. Two-hundred twenty-six letermovir recipients were identified and 7/15 (47%) with CMV DNAemia ≥200 IU/mL were successfully genotyped for UL56 resistance. A single C325Y resistance mutation was identified in an umbilical cord blood recipient. Ninety-five (42%), 43 (19%), and 15 (7%) patients had breakthrough CMV at any level, ≥150 IU/mL, and ≥500 IU/mL, respectively. Risk factors for breakthrough CMV reactivation at each viral threshold were examined. Cumulative steroid exposure was the strongest risk factor for CMV at all evaluated viral thresholds. Graft-versus-host disease prophylaxis with post-transplantation cyclophosphamide (aHR 2.34, 95% CI 1.28–4.28, p= 0.001) or calcineurin inhibitors plus mycophenolate (aHR 2.24, 95% CI 1.30–3.86, p= 0.004) were also associated with an increased risk of CMV reactivation at any level. De novo letermovir resistance is rare and can be successfully treated using other antivirals. Letermovir effectively prevents clinically significant CMV, however, subclinical CMV reactivation occurs frequently at our center.

•71% of patients given initial systemic treatment for cGVHD were alive at 1 year without recurrent malignancy or new systemic treatment.•Failure-free survival rates in this study compare favorably with those in other studies.•Results of this study could serve as a benchmark for outcomes in other resource-constrained locations and for the design of interventional clinical trials.

Chronic graft-versus-host disease (cGVHD) is an autoimmune-like syndrome. CXCR5-PD-1hi peripheral T-helper (Tph) cells have an important pathogenic role in autoimmune diseases, but the role of Tph cells in cGVHD remains unknown. We show that in patients with cGVHD, expansion of Tph cells among blood CD4+ T cells was associated with cGVHD severity. These cells augmented memory B-cell differentiation and production of immunoglobulin G via interleukin 21 (IL-21). Tph cell expansion was also observed in a murine model of cGVHD. This Tph cell expansion in the blood is associated with the expansion of pathogenic tissue-resident T-helper (Trh) cells that form lymphoid aggregates surrounded by collagen in graft-versus-host disease (GVHD) target tissues. Adoptive transfer experiments showed that Trh cells from GVHD target tissues give rise to Tph cells in the blood, and conversely, Tph cells from the blood give rise to Trh cells in GVHD target tissues. Tph cells in the blood and Trh cells in GVHD target tissues had highly overlapping T-cell receptor α and β repertoires. Deficiency of IL-21R, B-cell lymphoma 6 (BCL6), or T-bet in donor T cells markedly reduced the proportions of Tph cells in the blood and Trh cells in GVHD target tissues and reduced T-B interaction in the lymphoid aggregates. These results indicate that clonally related pathogenic Tph cells and Trh cells traffic between the blood and cGVHD target tissues, and that IL-21R-BCL6 signaling and T-bet are required for the development and expansion of Tph and Trh cells in the pathogenesis of cGVHD.

•cGVHD is characterized by an expansion of Tph cells in the blood of patients and mice with cGVHD.•Clonally related Tph cells and Trh cells traffic between the blood and cGVHD target tissues.

Acute graft-versus-host disease (GVHD) requiring second-line treatment represents a highly morbid complication of allogenic hematopoietic cell transplantation (HCT). Recent studies have defined short-term outcomes after second-line treatment for acute GVHD, but longer-term outcomes have not been well defined. We examined overall survival (OS) and failure-free-survival (FFS) of 216 patient who had HCT who received second-line treatment for acute GVHD. Failure time for FFS was defined as the earliest of death, relapse, or implementation of third-line treatment. Multivariable Cox regression was used to identify risk factors for mortality and failure, and predictive models were derived for 6- and 12-month mortality. Point estimates of OS at 6 and 12 months were 59% (95% confidence interval [CI], 52-65) and 52% (95% CI, 45-68), respectively. Point estimates of FFS at 6 and 12 months were 42% (95% CI, 35-48) and 37% (95% CI, 31-43), respectively. Predictive models for both end points included serum albumin and total bilirubin concentrations at the onset of second-line treatment, patient age at onset of second-line therapy, and a combination of abdominal pain/stage 4 gut involvement. Optimism-corrected areas under the receiver-operator characteristic curve and Brier scores were 77.4 and 0.169 for 6-month mortality, respectively, and 80.0 and 0.169 for 12-month mortality. We identify risk factors associated with mortality and failure after second-line treatment of acute GVHD, provide historical benchmarks for assessment of FFS and OS in other studies, and propose predictive models for 6- and 12-month mortality that could be used to generate population-specific benchmarks.

•Montelukast safely stabilized the majority of patients with established bronchiolitis obliterans syndrome (BOS) post-hematopoietic cell transplantation (HCT).•Improvement in symptoms and function and good 2-year survival occurred in responders.•Our data suggest that leukotrienes play a role in BOS occurring after HCT.

Previous studies have identified more than 200 genetic variants associated with acute or chronic graft-versus-host disease (aGVHD; cGVHD) or recurrent malignancy after allogeneic hematopoietic cell transplantation (HCT). We tested these candidate donor and recipient variants in a cohort of 4270 HCT recipients of European ancestry and in subcohorts of 1827 sibling and 1447 unrelated recipients who had 10/10 HLA-A, B, C, DRB1, and DQB1-matched donors. We also carried out a genome-wide association study (GWAS) for these same outcomes. The discovery and replication analysis of candidate variants identified a group of closely linked recipient HLA-DPB1 single-nucleotide polymorphisms (SNPs) associated with an increased risk of aGVHD and a corresponding decreased risk of recurrent malignancy after unrelated HCT. These results reflect a correlation with the level of HLA-DPB1 expression previously shown to affect the risks of aGVHD and relapse in unrelated recipients. Our GWAS identified an association of cGVHD with a locus of X-linked recipient intron variants in NHS, a gene that regulates actin remodeling and cell morphology. Evaluation of this association in a second replication cohort did not confirm the original replication results, and we did not reach any definitive conclusion regarding the validity of this discovery. The cohort used for our study is larger than those used in most previous HCT studies but is smaller than those typically used for other genotype-phenotype association studies. Genomic and disease data from our study are available for further analysis in combination with data from other cohorts.

Previous studies have identified more than 200 genetic variants associated with acute or chronic graft-versus-host disease (aGVHD; cGVHD) or recurrent malignancy after allogeneic hematopoietic cell transplantation (HCT). We tested these candidate donor and recipient variants in a cohort of 4270 HCT recipients of European ancestry and in subcohorts of 1827 sibling and 1447 unrelated recipients who had 10/10 HLA-A, B, C, DRB1, and DQB1-matched donors. We also carried out a genome-wide association study (GWAS) for these same outcomes. The discovery and replication analysis of candidate variants identified a group of closely linked recipient HLA-DPB1 single-nucleotide polymorphisms (SNPs) associated with an increased risk of aGVHD and a corresponding decreased risk of recurrent malignancy after unrelated HCT. These results reflect a correlation with the level of HLA-DPB1 expression previously shown to affect the risks of aGVHD and relapse in unrelated recipients. Our GWAS identified an association of cGVHD with a locus of X-linked recipient intron variants in NHS, a gene that regulates actin remodeling and cell morphology. Evaluation of this association in a second replication cohort did not confirm the original replication results, and we did not reach any definitive conclusion regarding the validity of this discovery. The cohort used for our study is larger than those used in most previous HCT studies but is smaller than those typically used for other genotype-phenotype association studies. Genomic and disease data from our study are available for further analysis in combination with data from other cohorts.

Allogeneic hematopoietic cell transplantation (allo-HCT) is an effective immunotherapy for various hematologic malignancies, predominantly through potent graft-versus-leukemia (GVL) effect. However, the mortality after allo-HCT is because of relapse of primary malignancy and followed by graft-vs-host-disease (GVHD) as a major cause of transplant-related mortality. Hence, strategies to limit GVHD while preserving the GVL effect are highly desirable. Ceramide, which serves a central role in sphingolipid metabolism, is generated by ceramide synthases (CerS1–6). In this study, we found that genetic or pharmacologic targeting of CerS6 prevented and reversed chronic GVHD (cGVHD). Furthermore, specific inhibition of CerS6 with ST1072 significantly ameliorated acute GVHD (aGVHD) while preserving the GVL effect, which differed from FTY720 that attenuated aGVHD but impaired GVL activity. At the cellular level, blockade of CerS6 restrained donor T cells from migrating into GVHD target organs and preferentially reduced activation of donor CD4 T cells. At the molecular level, CerS6 was required for optimal TCR signaling, CD3/PKCθ co-localization, and subsequent N-RAS activation and ERK signaling, especially on CD4+T cells. The current study provides rationale and means for targeting CerS6 to control GVHD and leukemia relapse, which would enhance the efficacy of allo-HCT as an immunotherapy for hematologic malignancies in the clinic.

Prior clinical trials largely considered prednisone 1 mg/kg per day with or without calcineurin inhibitor as standard initial therapy for chronic graft-versus-host disease (cGVHD), but uncertainty remains regarding the extent of practice variation and whether this affects subsequent outcomes. We assembled a cohort of 745 patients with cGVHD treated with initial systemic immune suppressive (IS) therapy from 3 prior cGVHD Consortium observational studies. Initial therapy was defined as first IS therapy started for cGVHD or prednisone increased to ≥0.4 mg/kg per day from lower doses within 30 days before cGVHD diagnosis to any time afterward. Initial therapies were nonprednisone IS therapies (n = 137, 18%), prednisone alone (n = 411, 55%), or prednisone plus other IS therapy (n = 197, 26%). In multivariate analysis, initial therapy group was not associated with failure-free survival (FFS; a composite of death, relapse, and new IS therapy), overall survival (OS), or nonrelapse mortality (NRM). Among the prednisone-based approaches, steroid dose was <0.25 (9%), 0.25 to 0.74 (36%), 0.75 to 1.25 (42%), or >1.25 mg/kg per day (13%). Prednisone dose within the patients treated with steroids was not significantly associated with FFS, OS, or NRM. No significant interactions were detected between overall cGVHD severity and either initial therapy group or prednisone dose for the outcomes of FFS, OS, or NRM. These observational data document heterogeneity in more contemporary cGVHD initial treatment practices, including prednisone dose and use of nonsteroid approaches. This variation was not associated with FFS, OS, or NRM. Prospective trials are needed to verify efficacy of reduced-dose prednisone or prednisone-free initial therapy approaches.

Previous studies have identified genetic variants associated with inflammatory bowel disease (IBD). We tested the hypothesis that some of these variants are also associated with the risk of moderate to severe gut graft-versus-host disease (GVHD) after allogeneic hematopoietic cell transplantation (HCT). Associations were evaluated initially in a discovery cohort of 1980 HCT recipients of European ancestry with HLA-matched related or unrelated donors. Associations discovered in this cohort were tested for replication in a separate cohort of 1294 HCT recipients. Among the 296 single-nucleotide polymorphisms and 26 HLA alleles tested, we found that the recipient rs1260326 homozygous T allele in GCKR was associated with a higher risk of stage 2 to 4 gut GVHD. No other candidate variants were associated with stage 2 to 4 gut GVHD. The rs1260326 variant resides in an IBD-associated locus containing FNDC4, a gene that encodes a secreted anti-inflammatory factor that dampens macrophage activity and improves colitis in mice. Our results suggest that targeting inflammatory macrophages with recombinant FNDC4 offers an attractive avenue of clinical investigation for management of IBD and gut GVHD.

Human cytomegalovirus (CMV) reactivation is a frequent complication of allogeneic hematopoietic cell transplantation (HCT). Despite routine screening for CMV reactivation and early antiviral treatment, the rates of CMV-related complications after HCT remain high. Genetic variants in both the donor and recipient have been associated with the risk of CMV reactivation and disease after HCT, but these associations have not been validated, and their clinical importance remains unclear. In this study, we assessed 117 candidate variants previously associated with CMV-related phenotypes for association with CMV reactivation and disease in a cohort of 2169 CMV-seropositive HCT recipients. We also carried out a genome-wide association study (GWAS) for CMV reactivation and disease in the same cohort. Both analyses used a prespecified discovery and replication approach to control the risk of false-positive results. Among the 117 candidate variants, our analysis implicates only the donor ABCB1rs1045642 genotype as a risk factor for CMV reactivation. This synonymous variant in P-glycoprotein may influence the risk of CMV reactivation by altering the efflux of cyclosporine and tacrolimus from donor lymphocytes. In the GWAS analysis, the donor CDC42EP3rs11686168 genotype approached the significance threshold for association with CMV reactivation, although we could not identify a mechanism to explain this association. The results of this study suggest that most genomic variants previously associated with CMV phenotypes do not significantly alter the risk for CMV reactivation or disease after HCT.

Human cytomegalovirus (CMV) reactivation is a frequent complication of allogeneic hematopoietic cell transplantation (HCT). Despite routine screening for CMV reactivation and early antiviral treatment, the rates of CMV-related complications after HCT remain high. Genetic variants in both the donor and recipient have been associated with the risk of CMV reactivation and disease after HCT, but these associations have not been validated, and their clinical importance remains unclear. In this study, we assessed 117 candidate variants previously associated with CMV-related phenotypes for association with CMV reactivation and disease in a cohort of 2169 CMV-seropositive HCT recipients. We also carried out a genome-wide association study (GWAS) for CMV reactivation and disease in the same cohort. Both analyses used a prespecified discovery and replication approach to control the risk of false-positive results. Among the 117 candidate variants, our analysis implicates only the donor ABCB1 rs1045642 genotype as a risk factor for CMV reactivation. This synonymous variant in P-glycoprotein may influence the risk of CMV reactivation by altering the efflux of cyclosporine and tacrolimus from donor lymphocytes. In the GWAS analysis, the donor CDC42EP3 rs11686168 genotype approached the significance threshold for association with CMV reactivation, although we could not identify a mechanism to explain this association. The results of this study suggest that most genomic variants previously associated with CMV phenotypes do not significantly alter the risk for CMV reactivation or disease after HCT.

Chronic graft-versus-host disease (GVHD) can be associated with significant morbidity, in part because of nonreversible fibrosis, which impacts physical functioning (eye, skin, lung manifestations) and mortality (lung, gastrointestinal manifestations). Progress in preventing severe morbidity and mortality associated with chronic GVHD is limited by a complex and incompletely understood disease biology and a lack of prognostic biomarkers. Likewise, treatment advances for highly morbid manifestations remain hindered by the absence of effective organ-specific approaches targeting “irreversible” fibrotic sequelae and difficulties in conducting clinical trials in a heterogeneous disease with small patient numbers. The purpose of this document is to identify current gaps, to outline a roadmap of research goals for highly morbid forms of chronic GVHD including advanced skin sclerosis, fasciitis, lung, ocular and gastrointestinal involvement, and to propose strategies for effective trial design. The working group made the following recommendations: (1) Phenotype chronic GVHD clinically and biologically in future cohorts, to describe the incidence, prognostic factors, mechanisms of organ damage, and clinical evolution of highly morbid conditions including long-term effects in children; (2) Conduct longitudinal multicenter studies with common definitions and research sample collections; (3) Develop new approaches for early identification and treatment of highly morbid forms of chronic GVHD, especially biologically targeted treatments, with a special focus on fibrotic changes; and (4) Establish primary endpoints for clinical trials addressing each highly morbid manifestation in relationship to the time point of intervention (early versus late). Alternative endpoints, such as lack of progression and improvement in physical functioning or quality of life, may be suitable for clinical trials in patients with highly morbid manifestations. Finally, new approaches for objective response assessment and exploration of novel trial designs for small populations are required.

Positive results from recent clinical trials have significantly expanded current therapeutic options for patients with chronic graft-versus-host disease (GVHD). However, new insights into the associations between clinical characteristics of chronic GVHD, pathophysiologic mechanisms of disease, and the clinical and biological effects of novel therapeutic agents are required to allow for a more individualized approach to treatment. The current report is focused on setting research priorities and direction in the treatment of chronic GVHD. Detailed correlative scientific studies should be conducted in the context of clinical trials to evaluate associations between clinical outcomes and the biological effect of systemic therapeutics. For patients who require systemic therapy but not urgent initiation of glucocorticoids, clinical trials for initial systemic treatment of chronic GVHD should investigate novel agents as monotherapy without concurrently starting glucocorticoids, to avoid confounding biological, pathological, and clinical assessments. Clinical trials for treatment-refractory disease should specifically target patients with incomplete or suboptimal responses to most recent therapy who are early in their disease course. Close collaboration between academic medical centers, medical societies, and industry is needed to support an individualized, biology-based strategic approach to chronic GVHD therapy.

Preventing chronic graft-versus-host disease (GVHD) remains challenging because the unique cellular and molecular pathways that incite chronic GVHD are poorly understood. One major point of intervention for potential prevention of chronic GVHD occurs at the time of transplantation when acute donor anti-recipient immune responses first set the events in motion that result in chronic GVHD. After transplantation, additional insults causing tissue injury can incite aberrant immune responses and loss of tolerance, further contributing to chronic GVHD. Points of intervention are actively being identified so that chronic GVHD initiation pathways can be targeted without affecting immune function. The major objective in the field is to continue basic studies and to translate what is learned about etiopathology to develop targeted prevention strategies that decrease the risk of morbid chronic GVHD without increasing the risks of cancer relapse or infection. Development of strategies to predict the risk of developing debilitating or deadly chronic GVHD is a high research priority. This working group recommends further interrogation into the mechanisms underpinning chronic GVHD development, and we highlight considerations for future trial design in prevention trials.

Donor T cells mediate both graft-versus-leukemia (GVL) activity and graft-versus-host disease (GVHD) after allogeneic hematopoietic cell transplantation (allo-HCT). Development of methods that preserve GVL activity while preventing GVHD remains a long-sought goal. Tolerogenic anti–interleukin-2 (IL-2) monoclonal antibody (JES6-1) forms anti–IL-2/IL-2 complexes that block IL-2 binding to IL-2Rβ and IL-2Rγ on conventional T cells that have low expression of IL-2Rα. Here, we show that administration of JES6 early after allo-HCT in mice markedly attenuates acute GVHD while preserving GVL activity that is dramatically stronger than observed with tacrolimus (TAC) treatment. The anti–IL-2 treatment downregulated activation of the IL-2-Stat5 pathway and reduced production of granulocyte-macrophage colony-stimulating factor (GM-CSF). In GVHD target tissues, enhanced T-cell programmed cell death protein 1 (PD-1) interaction with tissue–programmed cell death-ligand 1 (PD-L1) led to reduced activation of protein kinase–mammalian target of rapamycin pathway and increased expression of eomesodermin and B-lymphocyte-induced maturation protein-1, increased T-cell anergy/exhaustion, expansion of Foxp3–IL-10–producing type 1 regulatory (Tr1) cells, and depletion of GM-CSF–producing T helper type 1 (Th1)/cytotoxic T cell type 1 (Tc1) cells. In recipient lymphoid tissues, lack of donor T-cell PD-1 interaction with tissue PD-L1 preserved donor PD-1+TCF-1+Ly108+CD8+ T memory progenitors and functional effectors that have strong GVL activity. Anti–IL-2 and TAC treatments have qualitatively distinct effects on donor T cells in the lymphoid tissues, and CD8+ T memory progenitor cells are enriched with anti–IL-2 treatment compared with TAC treatment. We conclude that administration of tolerogenic anti–IL-2 monoclonal antibody early after allo-HCT represents a novel approach for preventing acute GVHD while preserving GVL activity.

Donor T cells mediate both graft-versus-leukemia (GVL) activity and graft-versus-host disease (GVHD) after allogeneic hematopoietic cell transplantation (allo-HCT). Development of methods that preserve GVL activity while preventing GVHD remains a long-sought goal. Tolerogenic anti–interleukin-2 (IL-2) monoclonal antibody (JES6-1) forms anti–IL-2/IL-2 complexes that block IL-2 binding to IL-2Rβ and IL-2Rγ on conventional T cells that have low expression of IL-2Rα. Here, we show that administration of JES6 early after allo-HCT in mice markedly attenuates acute GVHD while preserving GVL activity that is dramatically stronger than observed with tacrolimus (TAC) treatment. The anti–IL-2 treatment downregulated activation of the IL-2-Stat5 pathway and reduced production of granulocyte-macrophage colony-stimulating factor (GM-CSF). In GVHD target tissues, enhanced T-cell programmed cell death protein 1 (PD-1) interaction with tissue–programmed cell death-ligand 1 (PD-L1) led to reduced activation of protein kinase–mammalian target of rapamycin pathway and increased expression of eomesodermin and B-lymphocyte-induced maturation protein-1, increased T-cell anergy/exhaustion, expansion of Foxp3–IL-10–producing type 1 regulatory (Tr1) cells, and depletion of GM-CSF–producing T helper type 1 (Th1)/cytotoxic T cell type 1 (Tc1) cells. In recipient lymphoid tissues, lack of donor T-cell PD-1 interaction with tissue PD-L1 preserved donor PD-1+TCF-1+Ly108+CD8+T memory progenitors and functional effectors that have strong GVL activity. Anti–IL-2 and TAC treatments have qualitatively distinct effects on donor T cells in the lymphoid tissues, and CD8+T memory progenitor cells are enriched with anti–IL-2 treatment compared with TAC treatment. We conclude that administration of tolerogenic anti–IL-2 monoclonal antibody early after allo-HCT represents a novel approach for preventing acute GVHD while preserving GVL activity.

The 2005 National Institute of Health (NIH) Consensus Conference outlined histopathological diagnostic criteria for the major organ systems affected by both acute and chronic graft-versus-host disease (GVHD). The 2014 Consensus Conference led to this updated document with new information from histopathological studies of GVHD in the gut, liver, skin, and oral mucosa and an expanded discussion of GVHD in the lungs and kidneys. The recommendations for final histological diagnostic categories have been simplified from 4 categories to 3: no GVHD, possible GVHD, and likely GVHD, based on better reproducibility achieved by combining the previous categories of “consistent with GVHD” and “definite GVHD” into the single category of “likely GVHD.” Issues remain in the histopathological characterization of GVHD, particularly with respect to the threshold of histological changes required for diagnostic certainty. Guidance is provided for the incorporation of biopsy information into prospective clinical studies of GVHD, particularly with respect to biomarker validation.

We evaluated long-term outcome in 40 patients with MDS or AML, transplanted from related or unrelated donors following conditioning with targeted busulfan (Bu, over 4 days), fludarabine (Flu, 120 [n= 23] or 250 [n= 17] mg/m2) and thymoglobulin (THY). Compared to 95 patients conditioned with Bu/Cyclophosphamide (Cy) without THY, BuFluTHY-conditioned patients had lower rates of chronic graft-vs.-host disease (GVHD). Adjusted hazard ratios (HR) for BuFlu(120)THY and BuFlu(250)THY-conditioned patients were 1.60 (95% confidence interval (CI) 0.66–3.86) and 1.87 (0.68–5.11), respectively, for relapse; 0.77 (0.30–1.99) and 1.32 (0.54–3.23) for non-relapse mortality; 0.81 (0.42–1.57) and 1.38 (0.72–2.57) for overall mortality; and 0.78 (0.30–2.05) and 1.62 (0.63–4.41) for relapse or death (failure for relapse-free survival). At one year, 45% of BuFlu(120 or 250)THY-conditioned patients had mixed CD3+ chimerism compared to 0% with BuCy (p< 0.0001). None of 7 patients with long-term mixed chimerism had chronic GVHD; two relapsed, five remained stable mixed chimeras. THY is effective in reducing chronic GVHD, and long-term mixed T-cell chimerism can be compatible with relapse-free survival. However, Thy may also be associated with an increased risk of relapse and, dose-dependent, with non-relapse mortality.

Many studies have suggested that genetic variants in donors and recipients are associated with survival-related outcomes after allogeneic hematopoietic cell transplantation (HCT), but these results have not been confirmed. Therefore, the utility of testing genetic variants in donors and recipients for risk stratification or understanding mechanisms leading to mortality after HCT has not been established. We tested 122 recipient and donor candidate variants for association with nonrelapse mortality (NRM) and relapse mortality (RM) in a cohort of 2560 HCT recipients of European ancestry with related or unrelated donors. Associations discovered in this cohort were tested for replication in a separate cohort of 1710 HCT recipients. We found that the donor rs1051792 A allele in MICA was associated with a lower risk of NRM. Donor and recipient rs1051792 genotypes were highly correlated, making it statistically impossible to determine whether the donor or recipient genotype accounted for the association. Risks of grade 3 to 4 graft-versus-host disease (GVHD) and NRM in patients with grades 3 to 4 GVHD were lower with donor MICA-129Met but not with MICA-129Val, implicating MICA-129Met in the donor as an explanation for the decreased risk of NRM after HCT. Our analysis of candidate variants did not show any other association with NRM or RM. A genome-wide association study did not identify any other variants associated with NRM or RM.

Many studies have suggested that genetic variants in donors and recipients are associated with survival-related outcomes after allogeneic hematopoietic cell transplantation (HCT), but these results have not been confirmed. Therefore, the utility of testing genetic variants in donors and recipients for risk stratification or understanding mechanisms leading to mortality after HCT has not been established. We tested 122 recipient and donor candidate variants for association with nonrelapse mortality (NRM) and relapse mortality (RM) in a cohort of 2560 HCT recipients of European ancestry with related or unrelated donors. Associations discovered in this cohort were tested for replication in a separate cohort of 1710 HCT recipients. We found that the donor rs1051792 A allele in MICAwas associated with a lower risk of NRM. Donor and recipient rs1051792 genotypes were highly correlated, making it statistically impossible to determine whether the donor or recipient genotype accounted for the association. Risks of grade 3 to 4 graft-versus-host disease (GVHD) and NRM in patients with grades 3 to 4 GVHD were lower with donor MICA-129Met but not with MICA-129Val, implicating MICA-129Met in the donor as an explanation for the decreased risk of NRM after HCT. Our analysis of candidate variants did not show any other association with NRM or RM. A genome-wide association study did not identify any other variants associated with NRM or RM.

To identify plasma biomarkers associated with fibrotic mechanisms of chronic graft-versus-host disease (GVHD), we used multiplex mass spectrometry with pooled samples for biomarker discovery in comparing proteomic profiles between patients with newly diagnosed sclerotic chronic GVHD (n = 21), those with newly diagnosed nonsclerotic chronic GVHD (n = 33), and those without chronic GVHD (n = 20). Immunoassay was used to measure protein concentrations of individual discovery samples and 186 independent verification samples. The discovery mass spectrometry analysis identified 2 candidate proteins with at least 1.5-fold difference in sclerotic GVHD: Dickkopf-related protein 3 (DKK3) and interleukin-1 receptor accessory protein (IL1RAP). Analysis of individual discovery samples by immunoassay showed that DKK3, a modulator of the Wnt signaling pathway, was a biomarker for both sclerotic and nonsclerotic chronic GVHD. Verification analysis of 186 patients confirmed that elevated plasma DKK3 concentrations were associated with chronic GVHD, regardless of the presence or absence of sclerosis, and that the area under the receiver operating characteristic curve was 0.85 for association of DKK3 concentrations with chronic GVHD. Multiple linear regression analysis showed that chronic GVHD with or without steroid treatment and patient age were independently associated with DKK3 concentrations. Patients with high DKK3 concentrations had a higher nonrelapse mortality than those with low concentrations. The lower IL1RAP concentrations in patients with sclerotic GVHD compared with other conditions in the discovery cohort were not confirmed in the verification cohort. DKK3 is a novel biomarker for chronic GVHD. Further studies are needed to determine the biological functions of DKK3 in the pathogenesis of chronic GVHD.

To identify plasma biomarkers associated with fibrotic mechanisms of chronic graft-versus-host disease (GVHD), we used multiplex mass spectrometry with pooled samples for biomarker discovery in comparing proteomic profiles between patients with newly diagnosed sclerotic chronic GVHD (n = 21), those with newly diagnosed nonsclerotic chronic GVHD (n = 33), and those without chronic GVHD (n = 20). Immunoassay was used to measure protein concentrations of individual discovery samples and 186 independent verification samples. The discovery mass spectrometry analysis identified 2 candidate proteins with at least 1.5-fold difference in sclerotic GVHD: Dickkopf-related protein 3 (DKK3) and interleukin-1 receptor accessory protein (IL1RAP). Analysis of individual discovery samples by immunoassay showed that DKK3, a modulator of the Wnt signaling pathway, was a biomarker for both sclerotic and nonsclerotic chronic GVHD. Verification analysis of 186 patients confirmed that elevated plasma DKK3 concentrations were associated with chronic GVHD, regardless of the presence or absence of sclerosis, and that the area under the receiver operating characteristic curve was 0.85 for association of DKK3 concentrations with chronic GVHD. Multiple linear regression analysis showed that chronic GVHD with or without steroid treatment and patient age were independently associated with DKK3 concentrations. Patients with high DKK3 concentrations had a higher nonrelapse mortality than those with low concentrations. The lower IL1RAP concentrations in patients with sclerotic GVHD compared with other conditions in the discovery cohort were not confirmed in the verification cohort. DKK3 is a novel biomarker for chronic GVHD. Further studies are needed to determine the biological functions of DKK3 in the pathogenesis of chronic GVHD.

Steroid-resistant or steroid-refractory acute graft-versus-host disease (SR-aGVHD) poses one of the most vexing challenges faced by providers who care for patients after allogeneic hematopoietic cell transplantation. For the past 4 decades, research in the field has been driven by the premise that persistent graft-versus-host disease (GVHD) results from inadequate immunosuppression. Accordingly, most efforts to solve this problem have relied on retrospective or prospective studies testing agents that have direct or indirect immunosuppressive effects. Retrospective studies far outnumber prospective studies, and no controlled prospective trial has shown superior results for any agent over others. Truth be told, I do not know how to treat SR-aGVHD. Preclinical work during the past decade has provided fresh insights into the pathogenesis of acute GVHD, and translation of these insights toward development of more effective treatments for patients with SR-aGVHD has at last begun. Given the limited state of current knowledge, this “How I Treat” review highlights the overriding imperative to avoid harm in caring for patients with SR-aGVHD. Prospective trials that are widely available are urgently needed to advance the field.

Steroid-resistant or steroid-refractory acute graft-versus-host disease (SR-aGVHD) poses one of the most vexing challenges faced by providers who care for patients after allogeneic hematopoietic cell transplantation. For the past 4 decades, research in the field has been driven by the premise that persistent graft-versus-host disease (GVHD) results from inadequate immunosuppression. Accordingly, most efforts to solve this problem have relied on retrospective or prospective studies testing agents that have direct or indirect immunosuppressive effects. Retrospective studies far outnumber prospective studies, and no controlled prospective trial has shown superior results for any agent over others. Truth be told, I do not know how to treat SR-aGVHD. Preclinical work during the past decade has provided fresh insights into the pathogenesis of acute GVHD, and translation of these insights toward development of more effective treatments for patients with SR-aGVHD has at last begun. Given the limited state of current knowledge, this “How I Treat” review highlights the overriding imperative to avoid harm in caring for patients with SR-aGVHD. Prospective trials that are widely available are urgently needed to advance the field.

Implementation of the 2014 National Institutes of Health (NIH) response algorithm for joint/fascia graft-versus-host disease (GVHD) has identified real-world limits to its application. To refine the 2014 NIH response algorithm, we analyzed multicenter prospective observational data from the Chronic GVHD Consortium. The training cohort included 209 patients and the replication cohort included 191 patients with joint/fascia involvement during their course of chronic GVHD. Linear mixed models with random patient effect were used to evaluate correlations between response categories and clinician- or patient-perceived changes in joint status as an anchor of response. Analysis of the training cohort showed that a 2-point change in total photographic range of motion (P-ROM) score was clinically meaningful. The results also suggested that a change from 0 to 1 on the NIH joint/fascia score should not be considered as worsening and suggested that both the NIH joint/fascia score and total P-ROM score, but not individual P-ROM scores, should be used for response assessment. On the basis of these results, we developed an evidence-based refined algorithm, the utility of which was examined in an independent replication cohort. Using the refined algorithm, ∼40% of responses were reclassified, largely mitigating most divergent responses among individual joints and changes from 0 to 1 on the NIH joint/fascia score. The refined algorithm showed robust point estimates and tighter 95% confidence intervals associated with clinician- or patient-perceived changes, compared with the 2014 NIH algorithm. The refined algorithm provides a superior, evidence-based method for measuring therapeutic response in joint/fascia chronic GVHD.

Implementation of the 2014 National Institutes of Health (NIH) response algorithm for joint/fascia graft-versus-host disease (GVHD) has identified real-world limits to its application. To refine the 2014 NIH response algorithm, we analyzed multicenter prospective observational data from the Chronic GVHD Consortium. The training cohort included 209 patients and the replication cohort included 191 patients with joint/fascia involvement during their course of chronic GVHD. Linear mixed models with random patient effect were used to evaluate correlations between response categories and clinician- or patient-perceived changes in joint status as an anchor of response. Analysis of the training cohort showed that a 2-point change in total photographic range of motion (P-ROM) score was clinically meaningful. The results also suggested that a change from 0 to 1 on the NIH joint/fascia score should not be considered as worsening and suggested that both the NIH joint/fascia score and total P-ROM score, but not individual P-ROM scores, should be used for response assessment. On the basis of these results, we developed an evidence-based refined algorithm, the utility of which was examined in an independent replication cohort. Using the refined algorithm, ∼40% of responses were reclassified, largely mitigating most divergent responses among individual joints and changes from 0 to 1 on the NIH joint/fascia score. The refined algorithm showed robust point estimates and tighter 95% confidence intervals associated with clinician- or patient-perceived changes, compared with the 2014 NIH algorithm. The refined algorithm provides a superior, evidence-based method for measuring therapeutic response in joint/fascia chronic GVHD.

•Allogeneic hematopoietic cell transplantation (Allo-HCT) is a curative therapy for relapsed hematological malignances, but the same alloreactive T cells that eliminate malignant cells in the recipient also mediate graft-versus-host disease (GVHD), and in long-term Allo-HCT patients chronic GVHD (cGVHD) remains the major cause of morbidity and mortality. Th subsets (i.e., Th1, Th2, and Th17) have been associated with cGVHD in certain tissues, but the Th subsets involved in cutaneous cGVHD remain undefined. In the current studies, with a murine model of C57BL/6 donor to MHC-matched C3H.SW recipient, we observed that although IFN-γ +Th1 cells were dominant in the gut, liver, and skin during early acute GVHD, the skin showed a marked expansion of IFN-γ +IL-13 +Th1/Th2-like cells 30 days after HCT at the onset of cGVHD, while IFN-γ +IL-13 -Th1 cells remained dominant in the liver and intestines. The cutaneous Th1/Th2-like cells exhibited characteristics of Ly108 -CD69 +tissue resident memory T (Trm) cells. The expansion of cutaneous Th1/Th2-like cells was RORγt and ST2-dependent because T cells from RORγt -/-or ST2 -/-C57BL/6 donors did not show expansion of the cutaneous Th1/Th2-like cells or induce cutaneous cGVHD. These results indicate that 1) IFN-γ +/IL-13 +Th1/Th2-like CD4 +Trm cells likely play a critical role in the pathogenesis of cutaneous cGVHD; 2) the differentiation of IFN-γ +CD4 +Th1 cells into IFN-γ +IL-13 +Th1/Th2-like cells is RORγt and ST2-dependent. The molecular mechanisms that underpin this differentiation pathway are under investigation.

We and others have shown that tissue-resident memory CD4 +T cells play a critical role in maintaining chronic GVHD pathogenesis. However, the cellular and molecular mechanisms remain largely unknown. Ly108 and (TCF1) expression have been shown to reflect the stemness of memory CD8 +T cells. In the current studies, using the markers Ly108 (TCF1) and CD69, we identified four subsets of memory CD4 +T (Tm) cells in the GVHD target tissues, including Ly108 +CD69 -and Ly108 +CD69 +stem-like Tm cells, as well as Ly108 -CD69 -and Ly108 -CD69 +differentiatedTm cells. Compared to other Tm subsets, the Ly108 -CD69 +subset expressed the highest levels of IFN-γ and GM-CSF without upregulating anergy/exhaustion markers, indicating that they represent a terminally differentiated, tissue resident, pathogenic CD4 +memory T (Trm) subset. The Ly108 +Tm subsets showed self-renewal capacity and differentiation into Ly108 -Tm subsets, as demonstrated by adoptive transfer experiments. Using single-cell RNA sequencing (scRNA-seq) in conjunction with scTCR-seq analysis, we observed that Ly108 +CD69 -Tm subset was clonally related to the expanded Ly108 -CD69 -and Ly108 -CD69 +Tm subsets, suggesting a clonal expansion and differentiation of Ly108 +CD69 -stem-like memory T (Tsm) cells. In addition, we found that IFN-γ primed donor-type antigen-presenting cells (APCs) play an essential role in optimizing the transition from CD4 +Tsm cells to CD4 +Trm cells in STAT3- and BCL6-dependent manner, as indicated by ATAC-Seq analysis. Our results have elucidated a novel pathway of clonal expansion and differentiation of Tsm cells to Trm cells in the GVHD target tissues. These observations provide cellular and molecular mechanisms that explain how chronic GVHD is perpetuated by memory T cells in local tissues.

Preventing graft-versus-host disease (GVHD) while preserving graft-versus-leukemia/lymphoma (GVL) activity remains an elusive goal for allogeneic hematopoietic cell transplantation (HCT). It was reported by others that while donor naïve CD8 +T cells mediate both GVHD and GVL activity, donor memory CD8 +T cells could mediate GVL activity without GVHD. We recently reported that in vivo specific blockade of PD-L1/CD80 interactions augment tumor immunity mediated by memory CD8 +T cells (Zhang et al: PNAS 2023). In the current studies, we evaluated the impact of blockade of PD-L1/CD80 on GVHD induced by donor naïve CD8 +T cells and GVL activity-mediated by donor memory CD8 +T cells. Sorted naïve CD8 +T or memory CD8 +T cells and TCD-BM cells from C57BL/6 donors were transplanted into lethal TBI-conditioned BALB/c recipients with or without bearing ALL cancer cells. 4 days after HCT, the recipients were injected I.P. with anti-PD-L1 mAb (43H12) that specifically blocks PD-L1/CD80 interactions without inferring PD-L1/PD-1 interactions or control IgG. We observed that naïve but not memory CD8 +T cells severely infiltrated GVHD target tissues, and the memory CD8 +T cells expanded mainly in the lymphoid tissues. In vivo blockade of PD-L1/CD80 interactions augmented GVHD induced by the naïve T cells and GVL activity mediated by the memory CD8 +T cells. In addition, blockade of PD-L1/CD80 interactions increased production of granzyme B and inflammatory cytokines (IFN-g and TNF-α) of activated donor CD8 +T cells. Since cytolytic activity of effector CD8 +T cell is reported to be associated with its metabolic fitness, we evaluated the effect of blockade PD-L1/CD80 interactions on metabolism of alloreactive donor CD8 +T cells. And blockade of the interactions enhanced the fitness of mitochondria, as indicated by electronic microscopy analysis. The blockade also increased ECAR, OCR, and ATP production of the activated CD8 +T cells, with increased influx of glucose and fatty acids; and the blockade augmented mitophagy of the activated CD8 +T cells, as indicated by reducing mitochondria mass and dysfunctional mitochondria in the CD8 +T cells. The results indicate that 1) PD-L1/CD80 interactions play an important role in regulating the mitochondria function of activated alloreactive CD8 +T cells; 2) Blockade of PD-L1/CD80 interactions can augment GVL activity mediated by donor memory T cells without augmenting GVHD. This is different from blockade of PD-L1/PD-1 interactions that resulted in lethal GVHD.

Although differences in the incidence of chronic graft-versus-host disease (GVHD) across the races have been suggested, these have not been systematically investigated. This study compared the incidence, sites, severity, and outcomes of late acute GVHD and chronic GVHD according to National Institutes of Health (NIH) consensus criteria between Japanese (n = 413) and white (n = 708) patients after first allogeneic hematopoietic cell transplantation. Analysis was stratified according to bone marrow transplantation (BMT) or peripheral blood stem cell transplantation (PBSCT). Japanese patients, compared with white patients, had a similar incidence of late acute GVHD (BMT, 19% vs 16%; PBSCT, 19% vs 16%) but experienced more frequent liver late acute GVHD as defined by transaminase elevation (BMT, 79% vs 8%; PBSCT, 92% vs 33%) and less frequent gastrointestinal late acute GVHD (BMT, 11% vs 58%; PBSCT, 20% vs 68%). Japanese patients were more likely to discontinue systemic immunosuppression after late acute GVHD than white patients (hazard ratio, 3.68; 95% confidence interval, 1.96-6.94; P < .001). Japanese patients, compared with white patients, had a lower incidence of chronic GVHD (BMT, 15% vs 30% [P = .002]; PBSCT, 37% vs 45% [P < .001]) and experienced more frequent chronic GVHD of the mouth, eyes, and liver and less frequent gastrointestinal chronic GVHD. The duration of immunosuppressive treatment of NIH chronic GVHD was similar between the races. These differences could not be entirely attributed to practice variation between the centers. This study shows that the incidence, affected sites, severity, and clinical outcomes of late acute GVHD and NIH chronic GVHD differ between Japanese and white patients.

Although differences in the incidence of chronic graft-versus-host disease (GVHD) across the races have been suggested, these have not been systematically investigated. This study compared the incidence, sites, severity, and outcomes of late acute GVHD and chronic GVHD according to National Institutes of Health (NIH) consensus criteria between Japanese (n = 413) and white (n = 708) patients after first allogeneic hematopoietic cell transplantation. Analysis was stratified according to bone marrow transplantation (BMT) or peripheral blood stem cell transplantation (PBSCT). Japanese patients, compared with white patients, had a similar incidence of late acute GVHD (BMT, 19% vs 16%; PBSCT, 19% vs 16%) but experienced more frequent liver late acute GVHD as defined by transaminase elevation (BMT, 79% vs 8%; PBSCT, 92% vs 33%) and less frequent gastrointestinal late acute GVHD (BMT, 11% vs 58%; PBSCT, 20% vs 68%). Japanese patients were more likely to discontinue systemic immunosuppression after late acute GVHD than white patients (hazard ratio, 3.68; 95% confidence interval, 1.96-6.94; P< .001). Japanese patients, compared with white patients, had a lower incidence of chronic GVHD (BMT, 15% vs 30% [P= .002]; PBSCT, 37% vs 45% [P< .001]) and experienced more frequent chronic GVHD of the mouth, eyes, and liver and less frequent gastrointestinal chronic GVHD. The duration of immunosuppressive treatment of NIH chronic GVHD was similar between the races. These differences could not be entirely attributed to practice variation between the centers. This study shows that the incidence, affected sites, severity, and clinical outcomes of late acute GVHD and NIH chronic GVHD differ between Japanese and white patients.

Acute graft-versus-host-disease (GVHD) after non-myeloablative human leucocyte antigen (HLA)-matched, unrelated donor, allogeneic haemopoietic stem cell transplantation (HSCT) is associated with considerable morbidity and mortality. This trial aimed to evaluate the efficacy of adding sirolimus to the standard cyclosporine and mycophenolate mofetil prophylaxis therapy for preventing acute GVHD in this setting.