Impact of Donor Statin Treatment on Graft-versus-Host Disease after Allogeneic Hematopoietic Cell Transplantation.

Some retrospective studies have suggested that long-term donor statin use may protect against graft-versus-host disease (GVHD) in patients receiving cyclosporine (CSP)-based immunosuppression after allogeneic hematopoietic cell transplantation (HCT), but prospective studies of short-term treatment of donors with statin have shown conflicting results. We conducted 2 consecutive prospective clinical trials to assess whether donor statin treatment was associated with protection against severe acute GVHD (aGVHD). In a single-arm phase II trial (study 1), we evaluated whether short-term statin treatment of HLA-matched related donors for 14 days before HCT prevented grade III-IV aGVHD. In a prospective observational cohort study (study 2), we evaluated whether longer-term (>14 days) donor statin use was required for GVHD-protective effects. Study 1 was terminated after 6 of the 35 recipients (17%) developed grade III-IV GVHD. For study 2, we identified 135 patients whose unrelated donors had received long-term treatment with statins up to the time of HCT and 4942 patients whose donors had not received long-term statin treatment. The adjusted odds ratio for grade III-IV aGVHD (statin versus no statin) was .83 (95% confidence interval [CI], .46 to 1.50; P = .54). Multivariable analysis showed no statistically significant differences between the 2 groups in the risk of grade II-IV aGVHD, chronic GVHD, nonrelapse mortality, recurrent malignancy, or overall mortality. Among patients receiving CSP-based immunosuppression, including 35 with donors receiving long-term statin treatment and 973 with donors who did not receive statins, the adjusted odds ratio of grade III-IV aGVHD was .30 (95% CI, .07 to 1.35; P = .12). In study 1, short-term statin treatment of donors was ineffective in preventing grade III-IV GVHD. In study 2, in the prespecified subgroup of recipients given CSP-based immunosuppression, nondefinitive evidence suggested that donor statin use was associated with a reduced risk of severe aGVHD.

Donor T cell STAT3 deficiency enables tissue PD-L1-dependent prevention of graft-versus-host disease while preserving graft-versus-leukemia activity.

STAT3 deficiency (STAT3-/-) in donor T cells prevents graft-versus-host disease (GVHD), but the impact on graft-versus-leukemia (GVL) activity and mechanisms of GVHD prevention remains unclear. Here, using murine models of GVHD, we show that STAT3-/- donor T cells induced only mild reversible acute GVHD while preserving GVL effects against nonsusceptible acute lymphoblastic leukemia (ALL) cells in a donor T cell dose-dependent manner. GVHD prevention depended on programmed death ligand 1/programmed cell death protein 1 (PD-L1/PD-1) signaling. In GVHD target tissues, STAT3 deficiency amplified PD-L1/PD-1 inhibition of glutathione (GSH)/Myc pathways that regulate metabolic reprogramming in activated T cells, with decreased glycolytic and mitochondrial ATP production and increased mitochondrial ROS production and dysfunction, leading to tissue-specific deletion of host-reactive T cells and prevention of GVHD. Mitochondrial STAT3 deficiency alone did not reduce GSH expression or prevent GVHD. In lymphoid tissues, the lack of host-tissue PD-L1 interaction with PD-1 reduced the inhibition of the GSH/Myc pathway despite reduced GSH production caused by STAT3 deficiency and allowed donor T cell functions that mediate GVL activity. Therefore, STAT3 deficiency in donor T cells augments PD-1 signaling-mediated inhibition of GSH/Myc pathways and augments dysfunction of T cells in GVHD target tissues while sparing T cells in lymphoid tissues, leading to prevention of GVHD while preserving GVL effects.

Blockade of trans PD-L1 interaction with CD80 augments antitumor immunity.

PD-L1 has two receptors: PD-1 and CD80. Previous reports assumed that PD-L1 and CD80 interacted in trans, but recent reports showed that only cis PD-L1/CD80 interactions existed, and prevention of cis PD-L1/CD80 interactions on antigen-presenting cells (APCs) reduced antitumor immunity via augmenting PD-L1/PD-1 and CD80/CTLA4 interactions between T and APCs. Here, using tumor-bearing mice capable of cis and trans or trans only PD-L1/CD80 interactions, we show that trans PD-L1/CD80 interactions do exist between tumor and T cells, and the effects of trans PD-L1/CD80 interactions require tumor cell expression of MHC-I and T cell expression of CD28. The blockade of PD-L1/CD80 interactions in mice with both cis and trans interactions or with only trans interactions augments antitumor immunity by expanding IFN-γ-producing CD8+ T cells and IFN-γ-dependent NOS2-expressing tumor-associated macrophages. Our studies indicate that although cis and trans PD-L1/CD80 interactions may have opposite effects on antitumor immunity, the net effect of blocking PD-L1/CD80 interactions in vivo augments CD8+ T cell-mediated antitumor immunity.

Pathway-driven rare germline variants associated with transplant-associated thrombotic microangiopathy (TA-TMA).

The significance of rare germline mutations in transplant-associated thrombotic microangiopathy (TA-TMA) is not well studied. We performed a genetic association study in 100 adult TA-TMA patients vs. 98 post-transplant controls after matching by race, sex, and year. We focused on 5 pathways in complement, von Willebrand factor (VWF) function and related proteins, VWF clearance, ADAMTS13 function and related proteins, and endothelial activation (3641variants in 52 genes). In the primary analysis focused on 189 functional rare variants, no differential variant enrichment was observed in any of the pathways; specifically, 29 % TA-TMA and 33 % controls had at least 1 rare complement mutation. In the secondary analysis focused on 37 rare variants predicted to be pathogenic or likely pathogenic by ClinVar, Complement Database, or REVEL in-silico prediction tool, rare variants in the VWF clearance pathway were found to be significantly associated with TA-TMA (p = 0.008). On the gene level, LRP1 was the only one with significantly increased variants in TA-TMA in both analyses (p = 0.025 and 0.015). In conclusion, we did not find a significant association between rare variants in the complement pathway and TA-TMA; however, we discovered a new signal in the VWF clearance pathway driven by the gene LRP1 among likely pathogenic variants.

Prognostic Value of Cutaneous Disease Severity Estimates on Survival Outcomes in Patients With Chronic Graft-vs-Host Disease.

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.

Chronic graft-versus-host-disease treatment in Brazil: analyses of failure-free survival.

Failure-free survival (FFS), defined as the absence of new systemic treatment, recurrence of original malignancy and mortality not associated with recurrence after allogeneic hematopoietic stem cell transplantation (HCT), is a robust clinical measure to interpret results of initial systemic treatment of chronic graft-versus-host disease (cGVHD). We evaluate FFS after initial treatment of cGVHD in a mixed-race cohort from a resource-constrained country. This retrospective study included 354 consecutive patients after their first HCT between January 2014 and August 2020, who received initial systemic treatment for moderate or severe cGVHD at 13 Brazilian centers. Cox regression models were used to identify risk factors for treatment failure. The overall median follow-up among survivors was 28 months (range 1-71) after initial treatment. FFS was 89% at 6 months, 71% at 1 year and 52% at 2 years. New systemic treatment was the major cause of failure. In multivariable models, prior grades II-IV acute GVHD, a National Institutes of Health severity score of 3 in liver, gastrointestinal tract or lung involvement, and onset of initial treatment of cGVHD within 12 months after transplantation were all associated with an increased risk of treatment failure. Our results could serve as a benchmark for the design of future clinical trials evaluating initial treatment of cGVHD in resource-constrained locations.

Cytomegalovirus breakthrough and resistance during letermovir prophylaxis.

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.

Chronic GvHD NIH Consensus Project Biology Task Force: evolving path to personalized treatment of chronic GvHD.

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.

Durable discontinuation of systemic therapy in patients affected by chronic graft-versus-host disease.

Successful treatment of chronic graft-versus-host disease (GvHD) often requires long-term systemic therapy (ST). Durable discontinuation of ST reflects the resolution of active chronic GvHD. We evaluated the factors associated with durable ST discontinuation, defined as cessation of all ST for ≥12 months, using data from two prospectively followed cohorts from the Chronic GvHD Consortium (n=684). Transplant sources were peripheral blood (89%), bone marrow (6.6%), and cord blood (4.4%) from HLA matched related (37.6%), HLA matched unrelated (45%), and other donor types (18%). Half of the patients received non-myeloablative conditioning. The median time from transplantation to chronic GvHD diagnosis was 7.7 months (range, 1.0-141.3) and the median time from chronic GvHD onset to enrollment into the cohorts was 0.9 months (range, 0.0-12.0). The cumulative incidence estimate of durable ST discontinuation was 32% (95% confidence interval: 28%-37%) at 10 years after enrollment into the cohort. Among patients who discontinued ST, the median time from chronic GvHD diagnosis to durable ST discontinuation was 3.6 years (range, 1.2-10.5). In multivariate analysis, patients who received myeloablative conditioning, had chronic GvHD manifested as moderate/severe lower gastrointestinal involvement, and had a higher (worse) Lee symptom overall score were less likely to attain durable ST discontinuation. In contrast, mild lower gastrointestinal involvement and cord blood (vs. peripheral blood) as the graft source were associated with a greater likelihood of ST discontinuation. Although a minority of patients can discontinue ST permanently, most patients require prolonged ST. Viewing chronic GvHD in this way has implications for management approaches.

Trafficking between clonally related peripheral T-helper cells and tissue-resident T-helper cells in chronic GVHD.

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 ß 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.

Retention of Donor T Cells in Lymphohematopoietic Tissue and Augmentation of Tissue PD-L1 Protection for Prevention of GVHD While Preserving GVL Activity.

Allogeneic hematopoietic cell transplantation (Allo-HCT) is a curative therapy for hematological malignancies (i.e., leukemia and lymphoma) due to the graft-versus-leukemia (GVL) activity mediated by alloreactive T cells that can eliminate residual malignant cells and prevent relapse. However, the same alloreactive T cells can cause a serious side effect, known as graft-versus-host disease (GVHD). GVHD and GVL occur in distinct organ and tissues, with GVHD occurring in target organs (e.g., the gut, liver, lung, skin, etc.) and GVL in lympho-hematopoietic tissues where hematological cancer cells primarily reside. Currently used immunosuppressive drugs for the treatment of GVHD inhibit donor T cell activation and expansion, resulting in a decrease in both GVHD and GVL activity that is associated with cancer relapse. To prevent GVHD, it is important to allow full activation and expansion of alloreactive T cells in the lympho-hematopoietic tissues, as well as prevent donor T cells from migrating into the GVHD target tissues, and tolerize infiltrating T cells via protective mechanisms, such as PD-L1 interacting with PD-1, in the target tissues. In this review, we will summarize major approaches that prevent donor T cell migration into GVHD target tissues and approaches that augment tolerization of the infiltrating T cells in the GVHD target tissues while preserving strong GVL activity in the lympho-hematopoietic tissues.

Ceramide synthase 6 impacts T-cell allogeneic response and graft-versus-host disease through regulating N-RAS/ERK pathway.

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.

Prediction of outcomes after second-line treatment for acute graft-versus-host disease.

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.

Prospective Phase II Trial of Montelukast to Treat Bronchiolitis Obliterans Syndrome after Hematopoietic Cell Transplantation and Investigation into Bronchiolitis Obliterans Syndrome Pathogenesis.

Bronchiolitis obliterans syndrome (BOS) is a severe manifestation of chronic graft-versus-host disease (cGVHD) following hematopoietic cell transplantation (HCT). Montelukast interrupts cysteinyl leukotriene (CysLT) activity and may diminish the activation and homing of cells to bronchioles and subsequent fibrosis. We performed a prospective phase II trial to test whether montelukast altered lung decline for patients with BOS after HCT. In this single-arm, open-label, multi-institutional study, the primary endpoints were stability or improvement (<15% decline) in forced expiratory volume in 1 second (FEV1) and a <1-point decline in the slope of FEV1 after 6 months of treatment. Secondary endpoints included symptom and functional responses and immune correlates investigating the role of leukotrienes in BOS progression. The study enrolled 25 patients with moderate to severe lung disease after 3 months of stable cGVHD therapy. Montelukast was well tolerated, and no patient required escalation of BOS-directed therapy. At the primary endpoint, all 23 evaluable patients met the criteria for treatment success using FEV1% predicted, and all but 1 patient had stable or improved FEV1 slope. In those with a >5% improvement in FEV1, clinically meaningful improvements were seen in the Lee scores of breathing, energy, and mood. Improvements in the Human Activity Profile and 6-minute-walk test were observed in those with a <5% decline in FEV1. Overall survival was 87% at 2 years. Immune correlates showed elevated leukotriene receptor levels on blood eosinophils and monocytes versus healthy controls, elevated urine leukotrienes in 45% of the cohort, and CysLT receptors in bronchoalveolar lavage subsets and a predominance of Th2 cells, all pretreatment. These data suggest that montelukast may safely halt the progression of BOS after HCT, and that leukotrienes may play a role in the biology of BOS.

Naive T-Cell Depletion to Prevent Chronic Graft-Versus-Host Disease.

PURPOSE: Graft-versus-host disease (GVHD) causes morbidity and mortality following allogeneic hematopoietic cell transplantation. Naive T cells (TN) cause severe GVHD in murine models. We evaluated chronic GVHD (cGVHD) and other outcomes in three phase II clinical trials of TN-depletion of peripheral blood stem-cell (PBSC) grafts. METHODS: One hundred thirty-eight patients with acute leukemia received TN-depleted PBSC from HLA-matched related or unrelated donors following conditioning with high- or intermediate-dose total-body irradiation and chemotherapy. GVHD prophylaxis was with tacrolimus, with or without methotrexate or mycophenolate mofetil. Subjects received CD34-selected PBSC and a defined dose of memory T cells depleted of TN. Median follow-up was 4 years. The primary outcome of the analysis of cumulative data from the three trials was cGVHD. RESULTS: cGVHD was very infrequent and mild (3-year cumulative incidence total, 7% [95% CI, 2 to 11]; moderate, 1% [95% CI, 0 to 2]; severe, 0%). Grade III and IV acute GVHD (aGVHD) occurred in 4% (95% CI, 1 to 8) and 0%, respectively. The cumulative incidence of grade II aGVHD, which was mostly stage 1 upper gastrointestinal GVHD, was 71% (95% CI, 64 to 79). Recipients of matched related donor and matched unrelated donor grafts had similar rates of grade III aGVHD (5% [95% CI, 0 to 9] and 4% [95% CI, 0 to 9]) and cGVHD (7% [95% CI, 2 to 13] and 6% [95% CI, 0 to 12]). Overall survival, cGVHD-free, relapse-free survival, relapse, and nonrelapse mortality were, respectively, 77% (95% CI, 71 to 85), 68% (95% CI, 61 to 76), 23% (95% CI, 16 to 30), and 8% (95% CI, 3 to 13) at 3 years. CONCLUSION: Depletion of TN from PBSC allografts results in very low incidences of severe acute and any cGVHD, without apparent excess risks of relapse or nonrelapse mortality, distinguishing this novel graft engineering strategy from other hematopoietic cell transplantation approaches.

Genetic associations with immune-mediated outcomes after allogeneic hematopoietic cell transplantation.

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.

Long-term survival with mixed chimerism in patients with AML and MDS transplanted after conditioning with targeted busulfan, fludarabine, and thymoglobulin.

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.

A Model of Minor Histocompatibility Antigens in Allogeneic Hematopoietic Cell Transplantation.

Minor histocompatibility antigens (mHAg) composed of peptides presented by HLA molecules can cause immune responses involved in graft-versus-host disease (GVHD) and graft-versus-leukemia effects after allogeneic hematopoietic cell transplantation (HCT). The current study was designed to identify individual graft-versus-host genomic mismatches associated with altered risks of acute or chronic GVHD or relapse after HCT between HLA-genotypically identical siblings. Our results demonstrate that in allogeneic HCT between a pair of HLA-identical siblings, a mHAg manifests as a set of peptides originating from annotated proteins and non-annotated open reading frames, which i) are encoded by a group of highly associated recipient genomic mismatches, ii) bind to HLA allotypes in the recipient, and iii) evoke a donor immune response. Attribution of the immune response and consequent clinical outcomes to individual peptide components within this set will likely differ from patient to patient according to their HLA types.