Combination cell therapy leads to clonal deletion of donor-specific T cells in kidney transplant recipients.

BACKGROUND: Induction of donor-specific tolerance is a promising approach to achieve long-term graft patency in transplantation with little to no maintenance immunosuppression. Changes to the recipient's T cell receptor (TCR) repertoire are understood to play a pivotal role in the establishment of a robust state of tolerance in chimerism-based transplantation protocols. METHODS: We investigated changes to the TCR repertoires of patients participating in an ongoing prospective, controlled, phase I/IIa trial designed to evaluate the safety and efficacy of combination cell therapy in living donor kidney transplantation. Using high-throughput sequencing, we characterized the repertoires of six kidney recipients who also received bone marrow from the same donor (CKBMT), together with an infusion of polyclonal autologous Treg cells instead of myelosuppression. FINDINGS: Patients undergoing combination cell therapy exhibited partial clonal deletion of donor-reactive CD4+ T cells at one, three, and six months post-transplant, compared to control patients receiving the same immunosuppression regimen but no cell therapy (p = 0.024). The clonality, R20 and turnover rates of the CD4+ and CD8+ TCR repertoires were comparable in both groups, showing our protocol caused no excessive repertoire shift or loss of diversity. Treg clonality was lower in the case group than in control (p = 0.033), suggesting combination cell therapy helps to preserve Treg diversity. INTERPRETATION: Overall, our data indicate that combining Treg cell therapy with CKBMT dampens the alloimmune response to transplanted kidneys in humans in the absence of myelosuppression. FUNDING: This study was funded by the Vienna Science and Technology Fund (WWTF).

Retrospective analysis of the incidence and outcome of late acute and chronic graft-versus-host disease-an analysis from transplant centers across Europe.

Introduction: Chronic graft-versus-host disease (cGvHD) is a serious late complication of allogeneic hematopoietic stem cell transplantation (allo-HSCT). Methods: This multicenter analysis determined the cumulative incidence (CI) of cGvHD and late acute GvHD (laGvHD) and its impact on transplantation-related mortality (TRM), relapse (R), and overall survival (OS) in 317 patients [296 adults, 21 pediatrics (<12 years of age)] who underwent their first allo-HSCT in 2017. Results: The CI of laGvHD was 10.5% in adults and 4.8% in pediatrics, and the CI of cGvHD was 43.0% in all adult transplant patients and 50.2% in the adult at-risk cohort at the study end. The onset of cGvHD was de novo in 42.0% of patients, quiescent in 52.1%, and progressive in 5.9%. In adults, prophylactic use of antithymocyte globulin or posttransplant cyclophosphamide was associated with a significantly lower incidence of cGvHD (28.7%) vs. standard prophylaxis with calcineurin inhibitors (30.6%) and methotrexate/mycophenolate mofetil (58.4%) (all p < 0.01). TRM was significantly higher in patients with aGvHD (31.8%) vs. cGvHD (12.6%) and no GvHD (6.3%) (all p = 0.0001). OS in the adult at-risk cohort was significantly higher in patients with cGvHD (78.9%) vs. without (66.2%; p = 0.0022; HR 0.48) due to a significantly lower relapse rate (cGvHD: 14.5%; without cGvHD: 27.2%; p = 0.00016, HR 0.41). OS was also significantly higher in patients with mild (80.0%) and moderate (79.2%) cGvHD vs. without cGvHD (66.2%), excluding severe cGvHD (72.7%) (all p = 0.0214). Discussion: The negative impact of severe cGvHD on OS suggests a focus on prevention of severe forms is warranted to improve survival and quality of life.

Ruxolitinib for the treatment of acute graft-versus-host disease: a retrospective analysis.

Steroid-refractory acute graft-versus-host disease (aGvHD) is a serious complication after allogeneic hematopoietic stem cell transplantation, associated with significant mortality. Ruxolitinib was the first drug approved for aGvHD, based on results of the REACH2 trial; however, real-world data are limited. We retrospectively analyzed the safety and efficacy of ruxolitinib for treatment of aGvHD at our center from March 2016 to August 2022 and assessed biomarkers of risk. We identified 49 patients receiving ruxolitinib as second- (33/49), third- (11/49), fourth- (3/49), or fifth-line (2/49) treatment. Ruxolitinib was started on median day 11 (range, 7-21) after aGvHD onset; median duration of administration was 37 days (range, 20-86), with 10 patients continuing treatment at last follow-up. Median follow-up period was 501 days (range, 95-905). In the primary analysis at the 1-month assessment, overall response rate was 65%, and failure-free survival was 78%. Infectious complications ≥ CTCAE Grade III were observed in 10/49 patients within 1-month followup. Patients responding to ruxolitinib therapy required fewer steroids and exhibited lower levels of the serum biomarkers regenerating islet-derived protein 3-alpha, suppression of tumorigenicity 2, and the Mount Sinai Acute GVHD International Consortium algorithm probability. A univariate regression model revealed steroid-dependent aGvHD as a significant predictor of better response to ruxolitinib. Within 6-months follow-up, four patients experienced recurrence of underlying malignancy, and eight died due to treatment-related mortality. Overall, ruxolitinib was welltolerated and showed response in heavily pretreated patients, with results comparable to those of the REACH2 trial. Biomarkers may be useful predictors of response to ruxolitinib.

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.

Donor regulatory T cells rapidly adapt to recipient tissues to control murine acute graft-versus-host disease.

The adoptive transfer of regulatory T cells is a promising strategy to prevent graft-versus-host disease after allogeneic bone marrow transplantation. Here, we use a major histocompatibility complex-mismatched mouse model to follow the fate of in vitro expanded donor regulatory T cells upon migration to target organs. Employing comprehensive gene expression and repertoire profiling, we show that they retain their suppressive function and plasticity after transfer. Upon entering non-lymphoid tissues, donor regulatory T cells acquire organ-specific gene expression profiles resembling tissue-resident cells and activate hallmark suppressive and cytotoxic pathways, most evidently in the colon, when co-transplanted with graft-versus-host disease-inducing conventional T cells. Dominant T cell receptor clonotypes overlap between organs and across recipients and their relative abundance correlates with protection efficacy. Thus, this study reveals donor regulatory T cell selection and adaptation mechanisms in target organs and highlights protective features of Treg to guide the development of improved graft-versus-host disease prevention strategies.

Tocilizumab administration in cytokine release syndrome is associated with hypofibrinogenemia after chimeric antigen receptor T-cell therapy for hematologic malignancies.

Chimeric antigen receptor (CAR-) T cell therapy causes serious side effects including cytokine release syndrome (CRS). CRS-related coagulopathy is associated with hypofibrinogenemia that is thus far considered the result of disseminated intravascular coagulation (DIC) and liver dysfunction. We investigated incidence and risk factors for hypofibrinogenemia in 41 consecutive adult patients with hematologic malignancies (median age 69 years, range 38-83 years) receiving CAR-T cell therapy between 01/2020 and 05/2023 at the University Medical Center Regensburg. CRS occurred in 93% of patients and was accompanied by hypofibrinogenemia already from CRS grade 1. Yet, DIC and liver dysfunction mainly occurred in severe CRS (≥ grade 3). After an initial increase during CRS, fibrinogen levels dropped after administration of tocilizumab in a dose dependent manner (r = -0.44, p = 0.004). In contrast, patients who did not receive tocilizumab had increased fibrinogen levels. Logistic regression analysis identified tocilizumab as an independent risk factor for hypofibrinogenemia (odds ratio = 486, p < 0.001). We thus hypothesize that fibrinogen synthesis in CRS is upregulated in an interleukin-6-dependent acute phase reaction compensating for CRS-induced consumption of coagulation factors. Tocilizumab inhibits fibrinogen upregulation resulting in prolonged hypofibrinogenemia. These observations provide novel insights into the pathophysiology of hypofibrinogenemia following CAR-T cell therapy and emphasize the need for close fibrinogen monitoring after tocilizumab treatment of CRS.

Adoptive transfer of donor B lymphocytes: a phase 1/2a study for patients after allogeneic stem cell transplantation.

ABSTRACT: Immune reconstitution after allogeneic hematopoietic stem cell transplantation (allo-HSCT) is slow and patients carry a high and prolonged risk of opportunistic infections. We hypothesized that the adoptive transfer of donor B cells can foster after HSCT immuno-reconstitution. Here, we report, to our knowledge, the results of a first-in-human phase 1/2a study aimed to evaluate the feasibility and safety of adoptively transferred donor B cells and to test their activity upon recall vaccination. Good manufactoring practice (GMP) B-cell products were generated from donor apheresis products using 2-step magnetic cell separation. Fifteen patients who had undergone allo-HSCT were enrolled and treated after taper of immunosuppression (median, day +148; range, 130-160). Patients received 4 different doses of B cells (0.5 × 106 to 4.0 × 106 B cells per kg body weight). To test the activity of infused donor memory B cells in vivo, patients were vaccinated with a pentavalent vaccine 7 days after B-cell transfer. We observed the mobilization of plasmablasts and an increase in serum titers against vaccine antigens, with a stronger response in patients receiving higher B-cell numbers. Analysis of immunoglobulin VH-sequences by next-generation sequencing revealed that plasmablasts responding to vaccination originated from memory B-cell clones from the donor. Donor B-cell transfer was safe, as no Epstein-Barr virus (EBV) reactivation was observed, and only low-grade graft-versus-host disease (GVHD) occurred in 4 out of 15 patients. This pilot trial may pave the way for further studies exploring the adoptive transfer of memory B cells to reduce the frequency of infections after allo-HSCT. This trial was registered at ClinicalTrial.gov as #NCT02007811.

Bacteria and bacteriophage consortia are associated with protective intestinal metabolites in patients receiving stem cell transplantation.

The microbiome is a predictor of clinical outcome in patients receiving allogeneic hematopoietic stem cell transplantation (allo-SCT). Microbiota-derived metabolites can modulate these outcomes. How bacteria, fungi and viruses contribute to the production of intestinal metabolites is still unclear. We combined amplicon sequencing, viral metagenomics and targeted metabolomics from stool samples of patients receiving allo-SCT (n = 78) and uncovered a microbiome signature of Lachnospiraceae and Oscillospiraceae and their associated bacteriophages, correlating with the production of immunomodulatory metabolites (IMMs). Moreover, we established the IMM risk index (IMM-RI), which was associated with improved survival and reduced relapse. A high abundance of short-chain fatty acid-biosynthesis pathways, specifically butyric acid via butyryl-coenzyme A (CoA):acetate CoA-transferase (BCoAT, which catalyzes EC 2.8.3.8) was detected in IMM-RI low-risk patients, and virome genome assembly identified two bacteriophages encoding BCoAT as an auxiliary metabolic gene. In conclusion, our study identifies a microbiome signature associated with protective IMMs and provides a rationale for considering metabolite-producing consortia and metabolite formulations as microbiome-based therapies.

Incidence and Outcome of Atypical Manifestations of Chronic Graft-versus-Host Disease: Results From a Retrospective Single-Center Analysis.

Chronic graft-versus-host disease (cGVHD) is the leading cause of late nonrelapse mortality (NRM) after allogeneic hematopoietic stem cell transplantation (alloHSCT) and defined by 8 diagnostic target organs. Recently, provisional criteria for atypical manifestations of cGVHD that include manifestations in nonclassic organs as well as atypical manifestations in National Institutes of Health (NIH)-defined organs, were proposed by a NIH task force. Little is known about the incidence, risk factors, and impact on survival of atypical cGVHD, however. The aim of the present study was to analyze these parameters in a sequential patient population. We retrospectively screened 623 patients who underwent alloHSCT at the University Medical Center Regensburg between January 2008 and December 2020 for atypical cGVHD manifestations, applying the provisional NIH taskforce criteria. A total of 102 patients (16.4%) met the criteria, representing 25% of all cGVHD cases, and 14 patients (2.2%) had only atypical cGVHD. The most frequent manifestations were immune-mediated cytopenias (24.5%), renal cGVHD (13.7%) and (poly)serositis (13.7%). Multivariate analysis identified prior acute GVHD (odds ratio [OR], 2.28 and 2.93) and infusion of donor lymphocytes (OR, 1.77 for both) as risk factors for classic cGVHD and atypical cGVHD, whereas total body irradiation was an independent risk factor for atypical cGVHD manifestations only (OR, 1.76). Compared to patients without cGVHD, those with atypical and NIH-defined cGVHD showed similarly better overall survival (P = .034 and < .001) and low relapse-related mortality (P < .001 for both). NRM was significantly increased by atypical GVHD, but not by NIH-defined cGVHD (P = .019 and .10), which was driven only by a few atypical organ manifestations (eg, renal, restrictive lung disease, peripheral neuropathy), whereas others did not contribute to NRM (eg, thyroid gland, musculoskeletal, pancreas). In summary, atypical cGVHD is more common than previously estimated and has both similarities with and differences from NIH-defined cGVHD. In particular, the increased NRM and a subset of patients with only atypical cGVHD point to the urgent need to capture these manifestations in cGVHD cohorts, including analysis of treatment outcomes.

Survival advantage of treosulfan plus fludarabine (FT14) compared to busulfan plus fludarabine (FB4) in active acute myeloid leukemia post allogeneic transplantation: an analysis from the European Society for Blood and Marrow Transplantation (EBMT) Acute Leukemia Working Party (ALWP).

We compared FT14 (fludarabine 150-160 mg/m2, treosulfan 42 g/m2) versus FB4 (fludarabine 150-160 mg/m2, busulfan 12.8 mg/kg) in acute myeloid leukemia (AML) transplanted at primary refractory/relapsed disease. We retrospectively studied: (a) adults diagnosed with AML, (b) recipients of first allogeneic hematopoietic stem cell transplantation (HSCT) from unrelated/sibling donor (2010-2020), (c) HSCT with primary refractory/relapsed disease, (d) conditioning regimen with FT14 or FB4. We studied 346 patients, 113 transplanted with FT14, and 233 with FΒ4. FT14 patients were significantly older, more frequently had an unrelated donor and had received a lower dose of fludarabine. Cumulative incidence (CI) of acute graft-versus-host disease (GVHD) grade III-IV and extensive chronic GVHD was similar. With a median follow-up of 28.7 months, 2-year CI of relapse was 43.4% in FT14 versus 53.2% in FB4, while non-relapse mortality (NRM) was respectively 20.8% versus 22.6%. This led to 2-year leukemia-free survival (LFS) of 35.8% for FT14 versus 24.2% in FB4, and overall survival (OS) of 44.4% versus 34%. Adverse cytogenetics and conditioning regimen independently predicted CI of relapse. Furthermore, conditioning regimen was the only independent predictor of LFS, OS, and GVHD-free/relapse-free survival. Therefore, our real-world multicenter study suggests that FT14 is associated with better outcomes in primary refractory/relapsed AML.

Restrictive Versus Permissive Use of Broad-spectrum Antibiotics in Patients Receiving Allogeneic Stem Cell Transplantation and With Early Fever Due to Cytokine Release Syndrome: Evidence for Beneficial Microbiota Protection Without Increase in Infectious Complications.

BACKGROUND: Intestinal microbiome contributes to the pathophysiology of acute gastrointestinal (GI) graft-versus-host disease (GvHD) and loss of microbiome diversity influences the outcome of patients after allogeneic stem cell transplantation (SCT). Systemic broad-spectrum antibiotics have been identified as a major cause of early intestinal dysbiosis. METHODS: In 2017, our transplant unit at the university hospital in Regensburg changed the antibiotic strategy from a permissive way with initiation of antibiotics in all patients with neutropenic fever independent of the underlying cause and risk to a restrictive use in cases with high likelihood of cytokine release syndrome (eg, after anti-thymocyte globulin [ATG] therapy). We analyzed clinical data and microbiome parameters obtained 7 days after allogeneic SCT from 188 patients with ATG therapy transplanted in 2015/2016 (permissive cohort, n = 101) and 2918/2019 (restrictive cohort, n = 87). RESULTS: Restrictive antibiotic treatment postponed the beginning of antibiotic administration from 1.4 ± 7.6 days prior to 1.7 ± 5.5 days after SCT (P = .01) and significantly reduced the duration of antibiotic administration by 5.8 days (P < .001) without increase in infectious complications. Furthermore, we observed beneficial effects of the restrictive strategy compared with the permissive way on microbiome diversity (urinary 3-indoxylsulfate, P = .01; Shannon and Simpson indices, P < .001) and species abundance 7 days post-transplant as well as a positive trend toward a reduced incidence of severe GI GvHD (P = .1). CONCLUSIONS: Our data indicate that microbiota protection can be achieved by a more careful selection of neutropenic patients qualifying for antibiotic treatment during allogeneic SCT without increased risk of infectious complications.

Analysis of long-term mortality after total body irradiation-based and melphalan-based chemotherapy conditioning for acute myeloid leukemia.

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a curative treatment option for selected patients with acute myeloid leukemia. Yet, the influence of total body irradiation (TBI)-based conditioning as compared to non-TBI-based conditioning on long-term mortality is unclear. We retrospectively evaluated outcomes after TBI-based (n = 91) and non-TBI-based conditioning (melphalan-based, n = 248) for 1st allo-HSCT patients transplanted at the University Hospital Regensburg between 1999 and 2020. TBI was performed with an average dose rate of 4 cGy/min. Median follow-up was 8.3 years (interquartile range, 4.8-12.9 years). Cumulative incidence rates of 5-year non-relapse mortality (NRM) were 17% (95% confidence interval, CI, 10-25) and 33% (95% CI, 27-40) after TBI- and non-TBI-based conditioning (P < 0.001). Five-year cumulative incidences of relapse (CIR) were 42% (95% CI, 32-52) and 29% (95% CI, 23-35) after TBI- and non-TBI-based conditioning (P = 0.030). The 5-year OS was 54% (95% CI, 43-64) and 55% (95% CI, 48-62) after TBI- and non-TBI-based conditioning. Both groups had similar 100-day acute graft-versus-host disease (aGVHD, 43% vs. 40%) and 5-year chronic GVHD (34% vs. 36%). The multivariable regression models found no associations of TBI with the outcomes NRM, CIR, PFS, OS, aGVHD, and cGVHD. TBI was no risk factor for NRM, even including mortality caused by secondary malignancies. NRM was influenced by patient age, advanced disease status, and the use of female donors for male recipients. TBI- and non-TBI-based conditioning appear to be equally effective and tolerable for AML patients eligible for 1st allo-HSCT.

Intestinal IgA-positive plasma cells are highly sensitive indicators of alloreaction early after allogeneic transplantation and associate with both graft-versus-host disease and relapse-related mortality.

Intestinal immunoglobulin A (IgA) is strongly involved in microbiota homeostasis. Since microbiota disruption is a major risk factor of acute graft-versus-host disease (GvHD), we addressed the kinetics of intestinal IgA-positive (IgA+) plasma cells by immunohistology in a series of 430 intestinal biopsies obtained at a median of 1,5 months after allogeneic stem cell transplantation (allo-SCT) from 115 patients (pts) at our center. IgA+ plasma cells were located in the subepithelial lamina propria and suppressed in the presence of histological aGvHD (GvHD Lerner stage 0: 131+/-8 IgA+ plasma cells/mm2; stage 1-2: 108+/-8 IgA+ plasma cells/mm2; stage 3-4: 89+/-16 IgA+ plasma cells/mm2; P=0.004). Overall, pts with IgA+ plasma cells below median had an increased treatment related mortality (P=0.04). Time courses suggested a gradual recovery of IgA+ plasma cells after day 100 in the absence but not in the presence of GvHD. Vice versa IgA+ plasma cells above median early after allo-SCT were predictive of relapse and relapse-related mortality (RRM): pts with low IgA+ cells had a 15% RRM at 2 and at 5 years, while pts with high IgA+ cells had a 31% RRM at 2 years and more than 46% at 5 years; multivariate analysis indicated high IgA+ plasma cells in biopsies (hazard ratio =2.7; 95% confidence interval: 1.04-7.00) as independent predictors of RRM, whereas Lerner stage and disease stage themselves did not affect RRM. In contrast, IgA serum levels at the time of biopsy were not predictive for RRM. In summary, our data indicate that IgA+ cells are highly sensitive indicators of alloreaction early after allo-SCT showing association with TRM but also allowing prediction of relapse independently from the presence of overt GvHD.

Chronic Active Epstein-Barr Virus (EBV) Infection Controlled by Allogeneic Stem Cell Transplantation and EBV-Specific T Cells.

We report sustained remission of chronic active Epstein-Barr virus (EBV) infection in a 27-year-old female patient treated with third-party EBV-specific T cells followed by allogeneic hematopoietic stem cell transplantation (HSCT). The viremia cleared after administration of anti-T-lymphocyte globulin for graft-versus-host disease (GvHD) prophylaxis. Subsequent expansion of EBV-infected host T cells was controlled by transfusion of donor-derived EBV-specific T cells.

A non-antibiotic-disrupted gut microbiome is associated with clinical responses to CD19-CAR-T cell cancer immunotherapy.

Increasing evidence suggests that the gut microbiome may modulate the efficacy of cancer immunotherapy. In a B cell lymphoma patient cohort from five centers in Germany and the United States (Germany, n = 66; United States, n = 106; total, n = 172), we demonstrate that wide-spectrum antibiotics treatment ('high-risk antibiotics') prior to CD19-targeted chimeric antigen receptor (CAR)-T cell therapy is associated with adverse outcomes, but this effect is likely to be confounded by an increased pretreatment tumor burden and systemic inflammation in patients pretreated with high-risk antibiotics. To resolve this confounding effect and gain insights into antibiotics-masked microbiome signals impacting CAR-T efficacy, we focused on the high-risk antibiotics non-exposed patient population. Indeed, in these patients, significant correlations were noted between pre-CAR-T infusion Bifidobacterium longum and microbiome-encoded peptidoglycan biosynthesis, and CAR-T treatment-associated 6-month survival or lymphoma progression. Furthermore, predictive pre-CAR-T treatment microbiome-based machine learning algorithms trained on the high-risk antibiotics non-exposed German cohort and validated by the respective US cohort robustly segregated long-term responders from non-responders. Bacteroides, Ruminococcus, Eubacterium and Akkermansia were most important in determining CAR-T responsiveness, with Akkermansia also being associated with pre-infusion peripheral T cell levels in these patients. Collectively, we identify conserved microbiome features across clinical and geographical variations, which may enable cross-cohort microbiome-based predictions of outcomes in CAR-T cell immunotherapy.

Optimum timing of antithymocyte globulin in relation to adoptive regulatory T cell therapy.

Reducing the recipient's T cell repertoire is considered to increase the efficacy of regulatory T cell (Treg) therapy. This necessitates timing the administration of antithymocyte globulin (ATG) early enough before adoptive cell therapy (ACT) so that residual serum ATG does not deplete the transferred Tregs. The optimum time point in this regard has not been defined. Herein, we report the effects of residual serum ATG on the viability of an in vitro expanded Treg cell product used in a clinical trial of ACT in kidney transplant recipients (NCT03867617). Patients received ATG monotherapy (either 6 or 3 mg/kg body weight) without concomitant immunosuppression 2 to 3 weeks before transplantation and Treg transfer. An anti-ATG immunoglobulin G (IgG) immune response was elicited in all patients within 14 days. In turn, the elimination of total and Treg-specific ATG was accelerated substantially over control patients receiving the same dose of ATG with concomitant immunosuppression. However, ATG serum concentrations of <1 µg/mL, which had previously been reported as subtherapeutic threshold, triggered apoptosis of Tregs in vitro. Therefore, ATG levels need to decline to lower levels than those previously thought for efficacious Treg transfer. In 5 of 6 patients, such low levels of serum ATG considered safe for Treg transfer were reached within 2 weeks after ATG administration.

Reduced 8-Gray Compared to Standard 12-Gray Total Body Irradiation for Allogeneic Transplantation in First Remission Acute Lymphoblastic Leukemia: A Study of the Acute Leukemia Working Party of the EBMT.

In this registry-based study, we compared outcomes of allogeneic hematopoietic cell transplantation (allo-HCT) in adult patients with acute lymphoblastic leukemia (ALL) transplanted in first complete remission (CR-1), following conditioning with total body irradiation (TBI) at a standard 12-Gray or at a lower 8-Gray total dose. Patients received fludarabine (flu) as the sole chemotherapy complementing TBI. Eight-Gray TBI/flu was used in 494 patients and 12-Gray TBI/flu in 145 patients. Eighty-eight (23.1%) and 36 (29%) of the patients had Ph-negative B-ALL, 222 (58.3%) and 53 (42.7%) had Ph-positive B-ALL, 71 (18.6%) and 35 (28.2%) T-ALL, respectively (P = 0.008). Patients treated with 8-Gray were older than ones received 12-Gray (median 55.7 versus 40.3 years, P < 0.0001) and were more frequently administered in vivo T-cell depletion (71% versus 40%, P <0.0001). In a multivariate model adjusted for age, type of ALL, and other prognostic factors, leukemia-free survival (primary endpoint) as well as relapse, nonrelapse mortality, overall survival, and GVHD-free, relapse-free survival were not influenced by the TBI dose. These results were confirmed when we focused on patients <55 years of age (median 47 years). Patients with Ph-positive ALL or T-ALL had significantly better survival outcomes than ones with Ph-negative B-ALL, mainly due to significantly fewer relapses. We conclude that 8-Gray TBI is sufficient for adult patients with ALL transplanted in CR-1 with no additional benefit of augmenting the conditioning intensity to 12-Gray.

Murine cytomegalovirus reactivation concomitant with acute graft-versus-host disease is controlled by antibodies.

Reactivation of human cytomegalovirus (HCMV) from latency is a frequent complication following hematopoietic stem cell transplantation (HSCT). The development of acute graft-versus-host disease (GVHD) is a significant risk factor for HCMV disease. Using a murine GVHD model in animals latently infected with murine CMV (MCMV), we studied preventive and therapeutic interventions in this high-risk scenario of HSCT. Mice latently infected with MCMV experienced reactivated MCMV and developed disseminated MCMV infection concomitant with the manifestations of GVHD. Dissemination was accompanied by accelerated mortality. We demonstrate that MCMV reactivation and dissemination was modulated by MCMV-specific antibodies, thus demonstrating in vivo protective activity of antiviral antibodies. However, the efficacy of serum therapy required repetitive doses of high-titer immune serum secondary to the shortened serum half-life of IgG in animals with GVHD. In a complementary approach, treatment of GVHD by adoptive transfer of donor-derived Tregs facilitated production of MCMV-specific antibodies from newly developing donor-derived B cells. Together, our findings strongly suggest that antibodies play a major role in controlling recurrent MCMV infection that follows GVHD, and they argue for reassessing the potential of antibody treatments as well as therapeutic strategies that enhance de novo antibody development against HCMV.

Reg3α concentrations at day of allogeneic stem cell transplantation predict outcome and correlate with early antibiotic use.

Intestinal microbiome diversity plays an important role in the pathophysiology of acute gastrointestinal (GI) graft-versus-host disease (GVHD) and influences the outcome of patients after allogeneic stem cell transplantation (ASCT). We analyzed clinical data and blood samples taken preconditioning and on the day of ASCT from 587 patients from 7 German centers of the Mount Sinai Acute GVHD International Consortium, dividing them into single-center test (n = 371) and multicenter validation (n = 216) cohorts. Regenerating islet-derived 3α (Reg3α) serum concentration of day 0 correlated with clinical data as well as urinary 3-indoxylsulfate (3-IS) and Clostridiales group XIVa, indicators of intestinal microbiome diversity. High Reg3α concentration at day 0 of ASCT was associated with higher 1-year transplant-related mortality (TRM) in both cohorts (P < .001). Cox regression analysis revealed high Reg3α at day 0 as an independent prognostic factor for 1-year TRM. Multivariable analysis showed an independent correlation of high Reg3α concentrations at day 0 with early systemic antibiotic (AB) treatment. Urinary 3-IS (P = .04) and Clostridiales group XIVa (P = .004) were lower in patients with high vs those with low day 0 Reg3α concentrations. In contrast, Reg3α concentrations before conditioning therapy correlated neither with TRM nor disease or treatment-related parameters. Reg3α, a known biomarker of acute GI GVHD correlates with intestinal dysbiosis, induced by early AB treatment in the period of pretransplant conditioning. Serum concentrations of Reg3α measured on the day of graft infusion are predictive of the risk for TRM of ASCT recipients.

Downregulation of the vitamin D receptor expression during acute gastrointestinal graft versus host disease is associated with poor outcome after allogeneic stem cell transplantation.

The vitamin D receptor (VDR) is critical in regulating intestinal homeostasis and emerging evidence demonstrates that VDR deficiency is a critical factor in inflammatory bowel disease pathology. However, no clinical data exist regarding the intestinal expression of VDR in patients after allogeneic haematopoietic stem cell transplantation (HSCT). Analyzing intestinal biopsies from 90 patients undergoing HSCT with mortality follow-up, we demonstrated that patients with severe acute gastrointestinal graft versus host disease (GI-GvHD) showed significant downregulation of VDR gene expression compared to mild or no acute GI-GvHD patients (p = 0.007). Reduced VDR expression was already detectable at acute GI-GvHD onset compared to GvHD-free patients (p = 0.01). These results were confirmed by immunohistochemistry (IHC) where patients with severe acute GI-GvHD showed fewer VDR+ cells (p = 0.03) and a reduced VDR staining score (p = 0.02) as compared to mild or no acute GI-GvHD patients. Accordingly, low VDR gene expression was associated with a higher cumulative incidence of treatment-related mortality (TRM) (p = 1.6x10-6) but not with relapse-related mortality (RRM). A multivariate Cox regression analysis identified low VDR as an independent risk factor for TRM (p = 0.001, hazard ratio 4.14, 95% CI 1.78-9.63). Furthermore, VDR gene expression significantly correlated with anti-microbial peptides (AMPs) gene expression (DEFA5: r = 0.637, p = 7x10-5, DEFA6: r 0 0.546, p = 0.001). In conclusion, our findings suggest an essential role of the VDR in the pathogenesis of gut GvHD and the prognosis of patients undergoing HSCT.