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.

Adoptive transfer of donor-B lymphocytes: a phase I/IIa study for patients after allogeneic stem cell transplantation

Immune reconstitution after allogeneic hematopoietic stem cell transplantation (allo-HSCT) is slow and patients carry a high and prolonged risk for opportunistic infections. We hypothesized that the adoptive transfer of donor B cells can foster post-HSCT immuno-reconstitution. Here we report on the results of a first-in-human phase I/IIa study aimed to evaluate the feasibility and safety of adoptively transferred donor B cells and to test their activity upon recall vaccination. GMP-grade B-cell products were generated from donor apheresis products using a two-step magnetic cell separation. 15 allo-HSCT patients were enrolled and treated after taper of immunosuppression (median day +148, range 130 to 160). Patients received four different doses of B cells (0.5x106 - 4.0x106 B-cells per kg body weight (BW)). 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 mobilization of plasmablasts and an increase of serum titers against vaccine antigens with a stronger response in patients receiving higher B cell numbers. The analysis of immunoglobulin VH-sequences by next-generation-sequencing revealed that plasmablasts responding to the vaccination originated from memory B cell clones from the donor. Donor B cell transfer was safe as no EBV reactivation was observed, and only low-grade 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 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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

Impact of chronic graft-versus-host disease on quality of life and cognitive function of long-term transplant survivors after allogeneic hematopoietic stem cell transplantation with total body irradiation

BACKGROUND

Total body irradiation (TBI)-based-conditioning before allogeneic hematopoietic stem cell transplantation (allo-HSCT) is standard of care in patients with acute myeloid leukemia (AML) but can cause long-term morbidity. Data on the impact of chronic Graft-versus-host disease (cGvHD) on cognitive function (CF) and quality of life (QoL) of long-term transplant survivors are sparse.

METHODS

We analyzed patient-reported outcomes focusing on progression-free AML patients and 1st allo-HSCT applying a standardized TBI-technique with an average dose rate of 4 cGy/min to the total body and lung shielding in case of doses > 8 Gy. Instruments included the Functional Assessment of Cancer Therapy-Bone marrow transplant (FACT-BMT, version 4), the FACT-Cognition Function (FACT-Cog, version 3) and the Patient Health Questionaire-4 (PHQ-4). We put focus on the impact of cGvHD and compared the results to normative data derived from the general population.

RESULTS

Out of 41 eligible patients contacted, 32 (78.0%) patients with a medium follow-up of 154 months (Interquartile range 113, 191 months) participated in the study. Eleven patients (34.4%) had active cGvHD, 11 (34.4%) resolved cGvHD and 10 (31.3%) never had cGvHD. Patients with active cGvHD had poorer FACT-BMT, FACT-Cog and higher PHQ-4 scores compared to patients with resolved cGvHD or who never had cGvHD. Outcomes were similar in patients with resolved cGvHD and those who never had cGvHD. Patients with active cGvHD had similar FACT-Cog, but lower FACT-BMT in comparison to normative data. However, the overall patient sample had similar FACT-BMT and FACT-Cog in comparison to normative data.

CONCLUSION

Our data indicate that CF of long-term survivors upon TBI-based allo-HSCT is not impaired, even in the presence of active cGvHD. However, active cGvHD has a negative impact on QoL. Trial registration  The local Ethics Board of the University of Regensburg approved this study (Number 20-1810_1-101).

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.

Longitudinal Outcome over Two Decades of Unrelated Allogeneic Stem Cell Transplantation for Relapsed/Refractory Acute Myeloid Leukemia: An ALWP/EBMT Analysis

PURPOSE

We evaluated outcomes of unrelated transplantation for primary refractory/relapsed (ref/rel) acute myeloid leukemia (AML), comparing two cohorts according to the year of transplant, 2000-2009 and 2010-2019.

PATIENTS AND METHODS

Multivariable analyses were performed using the Cox proportional-hazards regression model.

RESULTS

3,430 patients were included; 876 underwent a transplant between 2000-2009 and 2554 in 2010-2019. Median follow-up was 8.7 (95% CI, 7.8-9.4) and 3.4 (95% CI, 3.1-3.6) years (P < 0.001). Median age was 52 (18-77) and 56 (18-79) years (P > 0.0001); 45.5% and 55.5% had refractory AML while 54.5% and 44.5% had relapsed AML. Conditioning was myeloablative in 60% and 52%, respectively. Neutrophil recovery and day 100 incidence of acute and 2-year incidence of chronic graft-versus-host disease (GvHD) were similar between the two periods. Two-year relapse incidence was higher for patients undergoing transplant in the 2000-2009 period versus those undergoing transplant in 2010-2019: 50.2% versus 45.1% (HR, 0.85; 95% CI, 0.74-0.97; P = 0. 002). Leukemia-free survival; overall survival; and GvHD-free, relapse-free survival were lower for the 2000-2009 period: 26% versus 32.1% (HR, 0.87; 95% CI, 0.78-0.97; P = 0.01), 32.1% versus 38.1% (HR, 0.86; 95% CI, 0.77-0.96; P = 0.01), and 21.5% versus 25.3% (HR, 0.89; 95% CI, 0.81-0.99; P = 0.03), respectively. Two-year nonrelapse mortality was not significantly different (23.8% vs. 23.7%; HR, 0.91; 95% CI, 0.76-1.11; P = 0.34).

CONCLUSIONS

Outcome of unrelated transplantation for patients with ref/rel AML has improved in the last two decades, rescuing about one third of the patients. See related commentary by Adrianzen-Herrera and Shastri, p. 4167.

Unusually swift response of relapsed Burkitt leukemia to R‐DHAP

Burkitt leukemia (BL) represents a highly aggressive lymphoma characterized by proliferation rates of around 100%, and a frequent spread into the central nervous system. If standard frontline chemotherapy fails, the prognosis is usually dismal, and reports on successful effective salvage therapy strategies for patients with relapsed/refractory BL are scant. Here, we report on a 40‐year‐old female patient who suffered an early relapse of BL three months after the completion of frontline chemoimmunotherapy. Strikingly, after only one cycle of R‐DHAP chemotherapy, the patient showed CR of BL enabling swift transition to a consolidating allogeneic stem cell transplantation. A 40‐year‐old previously healthy woman presented to the hospital with fatigue and incessant epistaxis, and a diagnosis of BL was made upon histological examination of a bone marrow biopsy. Treatment was initiated according to the GMALL 2002 B‐NHL/ALL protocol, which could induce complete molecular remission. Nevertheless, three months after chemotherapy, the patient exhibited BL relapse in the bone marrow, and on Fluorodeoxyglucose (FDG)–PET‐imaging. The relapse therapy was started with R‐DHAP, and after only one cycle, the patient once again entered complete remission (CR) paving the way for allogeneic stem cell transplantation. Unfortunately, the patient again relapsed five months after transplantation prompting salvage therapy with R‐DHAC and the execution of the second stem cell transplantation. However, one month after the second transplantation the patient presented with chemorefractory meningeosis leukemia resulting in the initiation of palliative care treatment. In summary, we report on rapid CR of relapsed BL after a single cycle of rituximab‐DHAP. Given a paucity of clinical trials on the treatment of patients with r/r BL, we intend to highlight the potential efficacy of rituximab‐DHAP as salvage therapy in those patients.

Low Intestinal IL22 Associates With Increased Transplant-Related Mortality After Allogeneic Stem Cell Transplantation

The role of IL-22 in adult patients undergoing allogeneic stem cell transplantation (SCT) is of major interest since animal studies showed a protective and regenerative effect of IL-22 in graft versus host disease (GvHD). However, no clinical data exist on the tissue expression. Here we demonstrate that patients not suffering from transplant-related mortality (TRM) show significantly upregulated IL22 expression during histological and clinical GI-GvHD (p = 0.048 and p = 0.022, respectively). In contrast, in GvHD patients suffering from TRM, IL22 was significantly lower (p = 0.007). Accordingly, lower IL22 was associated with a higher probability of TRM in survival analysis (p = 0.005). In a multivariable competing risk Cox regression analysis, low IL22 was identified as an independent risk factor for TRM (p = 0.007, hazard ratio 2.72, 95% CI 1.32 to 5.61). The expression of IL22 seemed to be microbiota dependent as broad-spectrum antibiotics significantly diminished IL22 expression (p = 0.019). Furthermore, IL22 expression significantly correlated with G-protein coupled receptor (GPR)43 (r = 0.263, p = 0.015) and GPR41 expression (r = 0.284, p = 0.009). In conclusion, our findings reveal an essential role of IL-22 for the prognosis of patients undergoing allogeneic SCT.

GPR Expression in Intestinal Biopsies From SCT Patients Is Upregulated in GvHD and Is Suppressed by Broad-Spectrum Antibiotics

Microbiota can exert immunomodulatory effects by short-chain fatty acids (SCFA) in experimental models of graft-versus-host disease (GvHD) after allogeneic hematopoietic stem cell transplantation (allo-SCT). Therefore we aimed to analyze the expression of SCFAs sensing G-protein coupled receptor GPR109A and GPR43 by quantitative PCR in 338 gastrointestinal (GI) biopsies obtained from 199 adult patients undergoing allo-SCT and assessed the interaction of GPR with FOXP3 expression and regulatory T cell infiltrates. GPR expression was strongly upregulated in patients with stage II-IV GvHD (p=0.000 for GPR109A, p=0.01 for GPR43) and at the onset of GvHD (p 0.000 for GPR109A, p=0.006 for GPR43) and correlated strongly with FOXP3 and NLRP3 expression. The use of broad-spectrum antibiotics (Abx) drastically suppressed GPR expression as well as FOXP3 expression in patients’ gut biopsies (p=0.000 for GPRs, FOXP3 mRNA and FOXP3+ cellular infiltrates). Logistic regression analysis revealed treatment with Abx as an independent factor associated with GPR and FOXP3 loss. The upregulation of GPRs was evident only in the absence of Abx (p=0.001 for GPR109A, p=0.014 for GPR43) at GvHD onset. Thus, GPR expression seems to be upregulated in the presence of commensal bacteria and associates with infiltration of FOXP3+ T regs, suggesting a protective, regenerative immunomodulatory response. However, Abx, which has been shown to induce dysbiosis, interferes with this protective response.

Human bocavirus 1 respiratory tract reactivations or reinfections in two adults, contributing to neurological deficits and death

Human bocavirus 1 (HBoV1) of the family Parvoviridae causes mild to life-threatening respiratory tract infections in young children, but, due to widespread immunity, it is uncommon in adults. HBoV1 reinfections or reactivations leading to casualties are rare, but might be underdiagnosed. We report two young adults, one previously healthy and one immunosuppressed, with rare diagnostic patterns of HBoV1 respiratory tract infection. Both patients exhibited very high loads of HBoV1 DNA in respiratory samples. The immunosuppressed patient was also HBoV1 DNA-positive in blood, stool and a colon biopsy, but exhibited prior HBoV1-specific high-avidity IgG and weak IgM positivity 9 months before the respiratory symptoms. Likewise, the previously healthy patient exhibited HBoV1 IgG of high avidity and very weak IgM in serum, pointing to prior immunity, but with a seroconversion in cerebrospinal fluid. This patient also showed strong HBoV2 cross-reactivity. The molecular and serological results, together with their ages, suggest that both patients exhibited unusual reinfection or reactivation of HBoV1, contributing to neurological deficits and death.

"This Graft-vs.-Host Disease Determines My Life. That's It."-A Qualitative Analysis of the Experiences and Needs of Allogenic Hematopoietic Stem Cells Transplantation Survivors in Germany

Background: Allogeneic hematopoietic stem cell transplantation (alloHSCT) is the only curative treatment modality for many patients affected by hematologic malignancies. However, it can cause debilitating long-term effects. Understanding the impact of alloHSCT on all aspects of the patients' life is required for optimal survivorship management. Aim: To explore in-depth HSCT-survivors' experiences and needs post-transplant. Partners were included to provide further information on survivors' needs and how care could be improved in this area. Methods: We conducted semi-structured face-to-face and phone interviews with alloHSCT-survivors and their partners referred to a survivorship clinic in Germany. Theoretical sampling was used to recruit participants. Data were analyzed using framework analysis. Results: Thirty-two survivors (consent rate: 100%, response rate: 100%) and eighteen partners (consent rate: 84%, response rate: 72%) participated. Survivors were aged between 25 and 68 years (Median: 48, IQR: 25.3) and partners were aged between 26 and 64 years (Median: 54, IQR: 16, SD: 12.8). The themes emerging from the data involved survivors' needs included (i) the diversity of long-term treatment side-effects; and (ii) time post discharge as a dynamic process with individual peaks of burden. Survivors and their partners also suggested strategies for mitigating these unmet needs, i.e., (iii) transparent communication and patient empowerment; and (iv) improvement in continuity of care system and help with claiming social benefits as cornerstones of optimal survivorship care. Conclusion: To our knowledge, this is one of the first qualitative studies focused on the views of German alloHSCT-survivors on the long-term effects of alloHSCT and the first study integrating the view of their partners. Healthcare providers could better support survivors with managing their symptoms and adhering to their prescribed care by ensuring comprehensive, transparent communication that helps increase survivors' understanding and involvement in their care. Further efforts should be made to provide patient-centered, continuous survivorship care that involves additional support with navigating the healthcare and social service system. Intervention studies are required to test the effectiveness of the suggested strategies.

A qualitative study on patients' and their support persons' preferences for receiving one longer consultation or two shorter consultations when being informed about allogeneic hematopoietic stem cell transplantation

Background

Allogeneic hematopoietic stem cell transplantation (alloHSCT) is the only potentially curative treatment option for many patients with hematological disorders but it includes a significant risk of mortality and long-term morbidity. Many patients and their support persons feel overwhelmed when being informed about alloHSCT and may benefit from improvements in consultation style and timing.

Aims

To explore, qualitatively, in a sample of hematological cancer patients and their support persons, their preferences for receiving one longer consultation or two shorter consultations when being informed about alloHSCT. Participants’ perceptions of when and how different consultation styles should be offered were also examined.

Methods

Semi-structured face-to-face and phone interviews were conducted. A purposeful sampling frame was used. Data were analysed using framework analysis.

Results

Twenty patients and 13 support persons were recruited (consent rate: 96%, response rate: 91%). Most patients (60%) and support persons (62%) preferred two shorter consultations over one longer consultation. This helped them digest and recall the information provided, remember questions they had, involve significant others and search for additional information. Patients would have liked to be offered paper and pen to take notes, take a break after 30 min and have their understanding checked at the end of the first consultation, e.g. using question prompt lists. Some patients and support persons preferred both consultations to happen on the same day to reduce waiting times as well as travel times and costs. Others preferred having a few days in-between both consultations to better help them prepare the second consultation. Participants reported varying preferences for different consultation styles depending on personal and disease-related characteristics, such as age, health literacy level and previous treatment.

Conclusion

To our knowledge, this is the first qualitative study to explore patients’ and their support persons’ preferences for having one longer consultation or two shorter consultations when being informed about alloHSCT. Receiving two shorter consultations may help patients process and recall the information provided and more actively involve their support persons. Clinicians should consider offering patients and their support persons to take a break after 30 min, provide paper and pen as well as question prompt lists.

Prolonged suppression of butyrate producing bacteria is associated with acute gastrointestinal graft-versus-host disease and transplant related mortality after allogeneic stem cell transplantation

BACKGROUND

Butyrogenic bacteria play an important role in gut microbiome homeostasis and intestinal epithelial integrity. Previous studies have demonstrated an association between administration of short chain fatty acids like butyrate and protection from acute graft-versus-host disease (aGvHD) after allogeneic stem cell transplantation (ASCT).

METHODS

Here we examined the abundance and butyrogenic capacity of butyrate producing bacteria in 28 healthy donors and 201 patients after ASCT. We prospectively collected serial stool samples and performed PCR analysis of the butyrate producing bacterial enzyme butyryl-CoA:acetate CoA-transferase (BCoAT) in fecal nucleic acid extracts.

RESULTS

Our data demonstrate a strong and prolonged suppression of butyrogenic bacteria early in the course of ASCT. In a multivariable analysis, early use of broad-spectrum antibiotics before day 0 (d 0, day of transplantation) was identified as independent factor associated with low BCoAT copies (odds ratio 0.370 (0.175-0.783), p=0.009). Diminished butyrogens correlated with other biomarkers of microbial diversity such as low 3-indoxyl sulfate (3-IS) levels, reduced abundance of Clostridiales and low inverse Simpson and effective Shannon indices (p<0.001, respectively). Low BCoAT copies at GvHD-onset correlated with GI-GvHD severity (p=0.002) and were associated with significantly higher GvHD associated mortality (p=0.040). Furthermore, low BCoAT copies at d 30 were associated with significantly higher transplant related mortality (p=0.017).

CONCLUSIONS

Our results are consistent with the hypothesis that alterations in the microbiome play an important role in GvHD pathogenesis and that microbial parameters such as BCoAT might serve as biomarkers to identify patients at high risk for developing lethal GI-GvHD.

Primary vaccination in adult patients after allogeneic hematopoietic stem cell transplantation - A single center retrospective efficacy analysis

Allogeneic hematopoietic stem cell transplantation (alloHSCT) results in a loss of humoral immunity and subsequent risk for severe infections. Thus, re-vaccination is required but may fail due to incomplete immune reconstitution. We retrospectively analyzed predictors of immune response to primary vaccination applied according to the EBMT (European Blood and Marrow Transplantation Group) recommendations. Serologic response to vaccination against diphtheria (D), tetanus (T), Bordetella pertussis (aP) and Haemophilus influenzae (Hib) (administrated as combined DTaP-Hib-IPV vaccination) was studied in 84 alloHSCT patients transplanted between 2008 and 2015 (age at alloHSCT: 18.6-70.6 years). All patients with a relapse-free survival of ≥9 months, at least 3 consecutive vaccinations and absence of intravenous immunoglobulin administration within 3 months before and after vaccination met the primary inclusion criteria. Additionally, immunological response to a pneumococcal conjugate vaccine was analyzed in a subgroup of 67 patients. Patients' characteristics at the time of first vaccination were recorded. Responses were measured as vaccine-specific antibody titers. Regarding DTaP-Hib-IPV vaccination, 89.3% (n = 75) of all patients achieved protective titers to at least 3 of the 4 vaccine components and were thus considered responders. 10.7% (n = 9) of the patients were classified as non-responders with positive immune response to less than 3 components. Highest response was observed for Hib (97.4%), tetanus (95.2%) and pneumococcal vaccination (83.6%) while only 68.3% responded to vaccination against Bordetella pertussis. Significant risk factors for failure of vaccination response included low B cell counts (p < 0.001; cut-off: 0.05 B cells/nl) and low IgG levels (p = 0.026; mean IgG of responders 816 mg/dl vs. 475 mg/dl of non-responders). Further, a trend was observed that prior cGvHD impairs vaccination response as 88.9% of the non-responders but only 54.7% of the responders had prior cGvHD (p = 0.073). The results demonstrate, that the currently proposed vaccination strategy leads to seroprotection in the majority of alloHSCT patients.

Second allogeneic haematopoietic cell transplantation using HLA-matched unrelated versus T-cell replete haploidentical donor and survival in relapsed acute myeloid leukaemia

Optimal donor choice for a second allogeneic haematopoietic cell transplant (allo-HCT) in relapsed acute myeloid leukaemia (AML) remains unknown. We compared overall survival (OS) using registry data from the Acute Leukemia Working Party (ALWP) of the European Society for Blood and Marrow Transplantation (EBMT) involving 455 adults who received a second allo-HCT from a human leucocyte antigen (HLA)-matched unrelated (MUD) (n = 320) or a haploidentical (n = 135) donor. Eligibility criteria required adults aged ≥18 years who received a second allo-HCT for treating AML relapse between 2005 and 2019. The primary end-point was OS. There was no statistically significant difference in the median (interquartile range) age between the groups, MUD 46 (35-58) versus haploidentical 44 (33-53) years (P = 0·07). The median OS was not different between the MUD and the haploidentical groups (10 vs. 11 months, P = 0·57). Similarly, the 2-year OS was 31% for the MUD and 29% for the haploidentical donor groups. The OS was worse if the procedure was performed with active AML [hazard ratio (HR) 1·42, 95% confidence interval (CI) 1·07-1·89; P = 0·02]. Conversely, a longer time from first allo-HCT to relapse (>13·2 months) was associated with better OS (HR 0·50, 95% CI 0·37-0·69; P < 0·0001). The results of the present analysis limit the ability to recommend one donor type over another when considering a second allo-HCT for relapsed AML. Our findings highlight that best OS is achieved when receiving the second allo-HCT in complete remission.

Single-cell chromatin accessibility landscape identifies tissue repair program in human regulatory T cells

Murine regulatory T (Treg) cells in tissues promote tissue homeostasis and regeneration. We sought to identify features that characterize human Treg cells with these functions in healthy tissues. Single-cell chromatin accessibility profiles of murine and human tissue Treg cells defined a conserved, microbiota-independent tissue-repair Treg signature with a prevailing footprint of the transcription factor BATF. This signature, combined with gene expression profiling and TCR fate mapping, identified a population of tissue-like Treg cells in human peripheral blood that expressed BATF, chemokine receptor CCR8 and HLA-DR. Human BATF⁺CCR8⁺ Treg cells from normal skin and adipose tissue shared features with nonlymphoid T follicular helper-like (Tfh-like) cells, and induction of a Tfh-like differentiation program in naive human Treg cells partially recapitulated tissue Treg regenerative characteristics, including wound healing potential. Human BATF⁺CCR8⁺ Treg cells from healthy tissue share features with tumor-resident Treg cells, highlighting the importance of understanding the context-specific functions of these cells.

Abatacept as salvage therapy in chronic graft-versus-host disease-a retrospective analysis

The immunomodulatory fusion protein abatacept has recently been investigated for the treatment of steroid-refractory chronic graft-versus-host disease (cGvHD) in a phase 1 clinical trial. We analyzed the safety and efficacy of abatacept for cGvHD therapy in a retrospective study with 15 patients who underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT) and received abatacept for cGvHD with a median age of 49 years. Grading was performed as part of the clinical routine according to the National Institute of Health’s (NIH) consensus criteria at initiation of abatacept and 1, 3, 6, 9 and 12 months thereafter. The median time of follow-up was 191 days (range 55–393 days). Best overall response rate (ORR) was 40%. In particular, patients with bronchiolitis obliterans syndrome showed significant clinical improvement and durable responses following abatacept treatment with a response rate of 89% based on improvement in lung severity score (n = 6) or stabilized lung function (n = 4) or both (n = 3). Infectious complications CTCAE °III or higher were observed in 3/15 patients. None of the patients relapsed from the underlying malignancy. Thus, abatacept appears to be a promising treatment option for cGvHD, in particular for patients with lung involvement. However, further evaluation within a phase 2 clinical trial is required.

A Prospective Controlled Trial to Evaluate Safety and Efficacy of in vitro Expanded Recipient Regulatory T Cell Therapy and Tocilizumab Together With Donor Bone Marrow Infusion in HLA-Mismatched Living Donor Kidney Transplant Recipients (Trex001)

Background: The induction of donor-specific immunological tolerance could improve outcome after kidney transplantation. However, no tolerance protocol is available for routine clinical use. Chimerism-based regimens hold promise, but their widespread application is impeded in part by unresolved safety issues. This study tests the hypothesis that therapy with polyclonal recipient regulatory T cells (Tregs) and anti-IL6R (tocilizumab) leads to transient chimerism and achieves pro-tolerogenic immunomodulation in kidney transplant recipients also receiving donor bone marrow (BM) without myelosuppressive conditioning of the recipient.

Methods/design: A prospective, open-label, controlled, single-center, phase I/IIa academic study is performed in HLA-mismatched living donor kidney transplant recipients.

Study group: Recipients of the study group receive in vitro expanded recipient Tregs and a donor bone marrow cell infusion within 3 days after transplantation and tocilizumab for the first 3 weeks post-transplant. In addition they are treated with thymoglobulin, belatacept, sirolimus, and steroids as immunosuppression. Starting 6 months post-transplant, sirolimus and steroids are withdrawn in a step-wise manner in stable patients.

Control group: Recipients of the control group are treated with thymoglobulin, belatacept, sirolimus, and steroids as immunosuppression. Co-primary endpoints of safety (impaired graft function [eGFR <35 mL/min/1.73 m²], graft-vs.-host disease or patient death by 12 months) and efficacy (total leukocyte donor chimerism within 28 days post-transplant) are assessed. Secondary endpoints include frequency of biopsy-proven acute rejection episodes and subclinical rejection episodes on surveillance biopsies, assessment of kidney graft function, and the evaluation whether the study protocol leads to detectable changes in the immune system indicative of pro-tolerogenic immune modulation.

Discussion: The results of this trial will provide evidence whether treatment with recipient Tregs and donor BM is feasible, safe and efficacious in leading to transient chimerism. If successful, this combination cell therapy has the potential to become a novel treatment option for immunomodulation in organ transplantation without the toxicities associated with myelosuppressive recipient conditioning.

Trial registration: European Clinical Trials Database EudraCT Nr 2018-003142-16 and clinicaltrials.gov NCT03867617.

Evaluation of the Cost of Survivorship Care After Allogeneic Hematopoeitic Stem Cell Transplantation-An Analysis of 2 German Transplantation Centers

The aim of the presented study was to analyze the care expenditure for outpatients after allogeneic hematopoietic stem cell transplantation (alloHSCT) done in accordance with the national, European guidelines and the German Social Law. We performed an analysis of the National and European survivorship care guidelines and in parallel recorded the time expenditure and staff costs separated according to different occupational groups involved in outpatient care at two German transplantation centers [University Hospital Regensburg (UKR) and University Hospital Hamburg-Eppendorf (UKE)]. In addition, we performed a comparison of real costs vs. reimbursed costs according to the standard rating benchmark catalog (EBM), which was supplemented by a survey of German transplantation centers. The results showed that the staff costs are only covered by the EBM for patients without complications during long-term follow-up care-notably, this accounts for 15% of alloHSCT patients. Staff costs for patients requiring treatment of graft-vs.-host disease or relapse of the malignant underlying malignancy exceed to the factor 6.5 (UKR) to 12 (UKE) of the EBM revenue, caused both by the increased duration and frequency of the outpatient visits. As a result of the survey at German transplant centers, 15 out of 18 responding centers reported a lack of cost coverage for follow-up care. Two/15 centers reported that survivorship care is limited to a restricted time, independent of patient's needs, due to a lack of cost reimbursement. The results show that alloHSCT survivorship care of patients requires significant staff resources, which are not covered by the current version of the German EBM catalog. New approaches to finance labor intensive after care of transplant patients are required.

Cyclophosphamide for salvage therapy of chronic graft-versus-host disease: a retrospective analysis

We retrospectively analyzed the safety and efficacy of cyclophosphamide (cyclo) for salvage treatment of chronic graft-versus-host disease (cGvHD) and cGvHD-associated (glomerulo-)nephritis at our center between 01/2010 and 11/2019. We identified 13 patients (pts) receiving cyclo for treatment of moderate (3/13) and severe (6/13) steroid-refractory cGvHD, cGvHD-associated (glomerulo-)nephritis (3/13), or vasculitis-like CNS manifestation of cGvHD (1/13). Cyclo was started on median day 509 (range 42-8193) after cGvHD onset; the median duration of application was 153 days (range 14-486) with 2/13 currently continuing treatment. The National Institute of Health organ grading and the intensity of immunosuppression (IS) were assessed at cyclo start and repeated after 3, 6, and 12 months. Response assessment was stopped at the start of any additional new IS. The median time of follow up was 407 days (range 86-1534). Best response was 1/13 CR, 6/13 PR, 4/13 SD, 1/13 MR, and 1/13 PD (ORR 54%). Significant and durable response was observed especially in cGvHD-associated (glomerulo-)nephritis (3/3). Infectious complications > CTCAE grade III were observed in 3/12 pts. During cyclo therapy, none of the pts suffered from recurrence of underlying malignancy. Overall, cyclo was relatively well tolerated and showed responses in heavily pretreated patients but requires further evaluation within clinical trials.

Regulatory cell therapy in kidney transplantation (The ONE Study): a harmonised design and analysis of seven non-randomised, single-arm, phase 1/2A trials

BACKGROUND

Use of cell-based medicinal products (CBMPs) represents a state-of-the-art approach for reducing general immunosuppression in organ transplantation. We tested multiple regulatory CBMPs in kidney transplant trials to establish the safety of regulatory CBMPs when combined with reduced immunosuppressive treatment.

METHODS

The ONE Study consisted of seven investigator-led, single-arm trials done internationally at eight hospitals in France, Germany, Italy, the UK, and the USA (60 week follow-up). Included patients were living-donor kidney transplant recipients aged 18 years and older. The reference group trial (RGT) was a standard-of-care group given basiliximab, tapered steroids, mycophenolate mofetil, and tacrolimus. Six non-randomised phase 1/2A cell therapy group (CTG) trials were pooled and analysed, in which patients received one of six CBMPs containing regulatory T cells, dendritic cells, or macrophages; patient selection and immunosuppression mirrored the RGT, except basiliximab induction was substituted with CBMPs and mycophenolate mofetil tapering was allowed. None of the trials were randomised and none of the individuals involved were masked. The primary endpoint was biopsy-confirmed acute rejection (BCAR) within 60 weeks after transplantation; adverse event coding was centralised. The RTG and CTG trials are registered with ClinicalTrials.gov, NCT01656135, NCT02252055, NCT02085629, NCT02244801, NCT02371434, NCT02129881, and NCT02091232.

FINDINGS

The seven trials took place between Dec 11, 2012, and Nov 14, 2018. Of 782 patients assessed for eligibility, 130 (17%) patients were enrolled and 104 were treated and included in the analysis. The 66 patients who were treated in the RGT were 73% male and had a median age of 47 years. The 38 patients who were treated across six CTG trials were 71% male and had a median age of 45 years. Standard-of-care immunosuppression in the recipients in the RGT resulted in a 12% BCAR rate (expected range 3·2-18·0). The overall BCAR rate for the six parallel CTG trials was 16%. 15 (40%) patients given CBMPs were successfully weaned from mycophenolate mofetil and maintained on tacrolimus monotherapy. Combined adverse event data and BCAR episodes from all six CTG trials revealed no safety concerns when compared with the RGT. Fewer episodes of infections were registered in CTG trials versus the RGT.

INTERPRETATION

Regulatory cell therapy is achievable and safe in living-donor kidney transplant recipients, and is associated with fewer infectious complications, but similar rejection rates in the first year. Therefore, immune cell therapy is a potentially useful therapeutic approach in recipients of kidney transplant to minimise the burden of general immunosuppression.

FUNDING

The 7th EU Framework Programme.

IL6-receptor antibody tocilizumab as salvage therapy in severe chronic graft-versus-host disease after allogeneic hematopoietic stem cell transplantation: a retrospective analysis

Chronic graft-versus-host disease (cGvHD) remains the most relevant factor affecting survival after allogeneic hematopoietic stem cell transplantation (alloHSCT). Besides corticosteroids (and ibrutinib in the USA), there is no established therapy for cGvHD. Tocilizumab, a humanized IgG1 IL6-receptor antibody, has shown efficacy in acute GvHD and cGvHD. We retrospectively analyzed the efficacy and safety of tocilizumab for the treatment of advanced cGvHD. Eleven patients with severe steroid refractory cGvHD (median age 49; range 21–62 years) that received at least two prior lines of therapy for cGvHD (range 2–8 regimens) were treated with tocilizumab (q4w, dosage 8 mg/kg IV) with a median number of 15 cycles (range 2–31). NIH consensus criteria grading for cGvHD were recorded prior to tocilizumab administration and after 3, 6, and 12 months of therapy. All patients received additional concomitant immunosuppression (IS) but no new IS within the last 4 weeks before start of tocilizumab and response assessment was terminated before start of any new IS. The median number of days between alloHSCT and initiation of tocilizumab therapy was 1033 days. Organs involved at initiation of tocilizumab therapy were skin (100%, all grade 3), eyes (82%), fascia (82%), mouth (64%), lungs (55%), and genitals (18%). Overall, 7/10 patients (70%) showed partial remission, 2/10 patients (20%) showed progressive cGvHD, 1/10 patient (10%) showed mixed response, and 1 patient died due to sepsis before first response assessment 1.5 months after initiation of treatment. Four patients required subsequent new immunosuppressive treatment. Two patients developed bacterial sepsis, one of whom died. The overall survival and relapse-free survival were 82% with an average follow-up of 22 months (range 1.5–52 months). Tocilizumab seems a promising treatment option in advanced cGvHD but further evaluation within a phase II trial is required.

Efficient treatment of murine acute GvHD by in vitro expanded donor regulatory T cells

Acute graft-versus-host disease (aGvHD) is a frequent complication after allogeneic bone marrow/stem cell transplantation (BMT/SCT) induced by co-transplanted alloreactive conventional donor T cells. We previously demonstrated that the adoptive transfer of donor CD4⁺CD25⁺Foxp3⁺ regulatory T cells (Treg) at the time of BMT prevents aGvHD in murine models. Yet, the therapeutic potential of donor Treg for the treatment of established aGvHD has not yet been studied in detail. We now used in vitro expanded phenotypically and functionally stable murine Treg to explore their therapeutic efficacy in haploidentical aGvHD models. Upon transfer donor Treg ameliorate clinical and histologic signs of aGvHD and significantly improve survival. They migrate to lymphoid as well as aGvHD target organs, predominantly the gastrointestinal tract, where they inhibit the proliferation of conventional T cells, reduce the influx of myeloid cells, and the accumulation of inflammatory cytokines. Successfully treated animals restore aGvHD-induced tissue damage in target organs and lymphoid tissues, thereby supporting lymphocyte reconstitution. The therapeutically applied Treg population survives long term without conversion into pathogenic effector T cells. These results demonstrate that donor Treg not only prevent aGvHD, but are also efficacious for the treatment of this life-threatening BMT complication.

Guidelines for the use of flow cytometry and cell sorting in immunological studies (second edition)

These guidelines are a consensus work of a considerable number of members of the immunology and flow cytometry community. They provide the theory and key practical aspects of flow cytometry enabling immunologists to avoid the common errors that often undermine immunological data. Notably, there are comprehensive sections of all major immune cell types with helpful Tables detailing phenotypes in murine and human cells. The latest flow cytometry techniques and applications are also described, featuring examples of the data that can be generated and, importantly, how the data can be analysed. Furthermore, there are sections detailing tips, tricks and pitfalls to avoid, all written and peer-reviewed by leading experts in the field, making this an essential research companion.

Long-term follow-up of rituximab in treatment of chronic graft-versus-host disease-single center experience

Rituximab was recently described also as first-line therapy of chronic graft-versus-host disease (cGvHD). We retrospectively analyzed the efficacy and safety of all patients receiving rituximab for treatment of cGvHD between 2005 and 2016 at the Regensburg University transplant center with a median follow-up after rituximab therapy of 2.8 years. Responses of 29 allogeneic stem cell-transplanted patients (median age 49) with previous failure of response to steroids including one patient after donor lymphocyte infusion were assessed. Three months after rituximab application, the overall response rate was 31% (7% complete (n = 2) and 24% partial remission (n = 7)). At 12 months, overall survival was 72% (n = 21) and failure-free survival was 24% (n = 7). We further analyzed associations of rituximab response with clinical characteristics showing a higher response rate in steroid-dependent cGvHD patients (89% of 9 responding compared to steroid refractory patients (11% responding)). However, this difference was not statistically significant. Seven patients (24%) (including four lethal infectious complications) developed serious infections requiring hospitalization within 1-9 months after rituximab therapy exclusively in patients failing to respond to rituximab. In conclusion, rituximab appears to be an effective treatment of cGvHD especially in steroid dependent patients, but identification of biomarker predicting response will be crucial to avoid long-term infectious morbidity and mortality in non-responders.

Imatinib dose reduction in major molecular response of chronic myeloid leukemia: results from the German Chronic Myeloid Leukemia-Study IV

Standard first-line therapy of chronic myeloid leukemia is treatment with imatinib. In the randomized German Chronic Myeloid Leukemia-Study IV, more potent BCR-ABL inhibition with 800 mg (‘high-dose’) imatinib accelerated achievement of a deep molecular remission. However, whether and when a de-escalation of the dose intensity under high-dose imatinib can be safely performed without increasing the risk of losing deep molecular response is unknown. To gain insights into this clinically relevant question, we analyzed the outcome of imatinib dose reductions from 800 mg to 400 mg daily in the Chronic Myeloid Leukemia-Study IV. Of the 422 patients that were randomized to the 800 mg arm, 68 reduced imatinib to 400 mg after they had achieved at least a stable major molecular response. Of these 68 patients, 61 (90%) maintained major molecular remission on imatinib at 400 mg. Five of the seven patients who lost major molecular remission on the imatinib standard dose regained major molecular remission while still on 400 mg imatinib. Only two of 68 patients had to switch to more potent kinase inhibition to regain major molecular remission. Importantly, the lengths of the intervals between imatinib high-dose treatment before and after achieving major molecular remission were associated with the probabilities of maintaining major molecular remission with the standard dose of imatinib. Taken together, the data support the view that a deep molecular remission achieved with high-dose imatinib can be safely maintained with standard dose in most patients. Study protocol registered at clinicaltrials.gov 00055874.

Biomarkers in chronic graft-versus-host disease: quo vadis?

Biomarkers are increasingly used for diagnosis and treatment of transplant-related complications including the first biomarker-driven interventional trials of acute graft-versus-host disease (GvHD). In contrast, the development of biomarkers of chronic GvHD (cGvHD) has lagged behind due to a broader variety of manifestations, overlap with acute GvHD, a greater variation in time to onset and maximum severity, and lack of sufficient patient numbers within prospective trials. An international workshop organized by a North-American and European consortium was held in Marseille in March 2017 with the goal to discuss strategies for future biomarker development to guide cGvHD therapy. As a result of this meeting, two areas were prioritized: the development of prognostic biomarkers for subsequent onset of moderate/severe cGvHD, and in parallel, the development of qualified clinical-grade assays for biomarker quantification. The most promising prognostic serum biomarkers are CXCL9, ST2, matrix metalloproteinase-3, osteopontin, CXCL10, CXCL11, and CD163. Urine-proteomics and cellular subsets (CD4+ T-cell subsets, NK cell subsets, and CD19+CD21low B cells) represent additional potential prognostic biomarkers of cGvHD. A joint effort is required to verify the results of numerous exploratory trials before any of the potential candidates is ready for validation and subsequent clinical application.

CD83 expression is essential for Treg cell differentiation and stability

Foxp3-positive regulatory T cells (Tregs) are crucial for the maintenance of immune homeostasis and keep immune responses in check. Upon activation, Tregs are transferred into an effector state expressing transcripts essential for their suppressive activity, migration, and survival. However, it is not completely understood how different intrinsic and environmental factors control differentiation. Here, we present for the first time to our knowledge data suggesting that Treg-intrinsic expression of CD83 is essential for Treg differentiation upon activation. Interestingly, mice with Treg-intrinsic CD83 deficiency are characterized by a proinflammatory phenotype. Furthermore, the loss of CD83 expression by Tregs leads to the downregulation of Treg-specific differentiation markers and the induction of an inflammatory profile. In addition, Treg-specific conditional knockout mice showed aggravated autoimmunity and an impaired resolution of inflammation. Altogether, our results show that CD83 expression in Tregs is an essential factor for the development and function of effector Tregs upon activation. Since Tregs play a crucial role in the maintenance of immune tolerance and thus prevention of autoimmune disorders, our findings are also clinically relevant.

Assessment of imatinib as first-line treatment of chronic myeloid leukemia: 10-year survival results of the randomized CML study IV and impact of non-CML determinants

Chronic myeloid leukemia (CML)-study IV was designed to explore whether treatment with imatinib (IM) at 400 mg/day (n=400) could be optimized by doubling the dose (n=420), adding interferon (IFN) (n=430) or cytarabine (n=158) or using IM after IFN-failure (n=128). From July 2002 to March 2012, 1551 newly diagnosed patients in chronic phase were randomized into a 5-arm study. The study was powered to detect a survival difference of 5% at 5 years. After a median observation time of 9.5 years, 10-year overall survival was 82%, 10-year progression-free survival was 80% and 10-year relative survival was 92%. Survival between IM400 mg and any experimental arm was not different. In a multivariate analysis, risk group, major-route chromosomal aberrations, comorbidities, smoking and treatment center (academic vs other) influenced survival significantly, but not any form of treatment optimization. Patients reaching the molecular response milestones at 3, 6 and 12 months had a significant survival advantage. For responders, monotherapy with IM400 mg provides a close to normal life expectancy independent of the time to response. Survival is more determined by patients' and disease factors than by initial treatment selection. Although improvements are also needed for refractory disease, more life-time can currently be gained by carefully addressing non-CML determinants of survival.

Relation between Acute GVHD and NK Cell Subset Reconstitution Following Allogeneic Stem Cell Transplantation

One of the major challenges of allogeneic stem cell transplantation (allo-SCT) is to reduce the risk of graft-versus-host disease (GVHD) while boosting the graft-versus-leukemia (GVL) effect. The reconstitution of natural killer (NK) cells following allo-SCT is of notable interest due to their known capability to induce GVL without GVHD. Here, in this study, we investigate the association between the incidence and severity of acute graft-versus-host disease (aGVHD) and the early reconstitution of NK cell subsets following allo-SCT. We analyzed 342 samples from 107 patients using flow cytometry, with a focus on immature CD56^high and mature cytotoxic CD56^dim NK cells. Longitudinal analysis of immune reconstitution after allo-SCT showed that the incidence of aGVHD was associated with a delayed expansion of the entire NK cell population, in particular the CD56^high subset. Notably, the disturbed reconstitution of the CD56^high NK cells also correlated with the severity of aGVHD.

Altered immune reconstitution of B and T cells precedes the onset of clinical symptoms of chronic graft-versus-host disease and is influenced by the type of onset

We analyzed lymphocyte subpopulations and cytokines 3 months after allogeneic hematopoietic stem cell transplantation aiming to identify predictive cellular and serum markers for chronic graft-versus-host disease (cGVHD). Samples of 49 patients (pts) (no cGVHD (n = 14), subsequent quiescent onset (n = 16), de novo onset of cGVHD (n = 19)) were analyzed in the absence of active GVHD by flow cytometry and enzyme-linked immunosorbent assay. All mean absolute cell counts are presented as cells per microliter; relative cell counts are presented as percentage of lymphocytes. Pts with subsequent de novo cGVHD had significantly higher relative and absolute counts of CD4+ T cells including higher absolute counts of CD4+ memory T cells (22.36%; 206.55/μl; 136/μl, respectively) compared to pts with subsequent quiescent onset of cGVHD (12.41%; 83.42/μl; 54.3/μl) and pts without cGVHD (10.55%) with regard to relative counts of CD4+ T cells. Similarly, significantly more relative and absolute regulatory T cell numbers (CD4+FOXP3+) were detected in pts with de novo onset of cGVHD (3.08% and 24.63/μl) compared to those in pts without (1.25% and 9.06/μl) or with quiescent onset of cGVHD (1.15% and 6.91/μl). Finally, relative B cell counts, including naïve and memory B cells, were also significantly decreased in pts developing quiescent cGVHD (0.85, 0.73, 0.12% resp.) when compared to pts with de novo onset (5.61, 5.24, 0.38%). The results demonstrate that alterations in immune reconstitution are already present before onset of clinical symptoms and differ between de novo and quiescent onset of disease.

High-dose chemotherapy with autologous haemopoietic stem cell transplantation for newly diagnosed primary CNS lymphoma: a prospective, single-arm, phase 2 trial

BACKGROUND

High-dose methotrexate-based chemotherapy is standard for primary CNS lymphoma, but most patients relapse. High-dose chemotherapy with autologous stem cell transplantation (HCT-ASCT) is supposed to overcome the blood-brain barrier and eliminate residual disease in the CNS. We aimed to investigate the safety and efficacy of HCT-ASCT in patients with newly diagnosed primary CNS lymphoma.

METHODS

In this prospective, single-arm, phase 2 trial, we recruited patients aged 18-65 years with newly diagnosed primary CNS lymphoma and immunocompetence, with no limitation on clinical performance status, from 15 hospitals in Germany. Patients received five courses of intravenous rituximab 375 mg/m(2) (7 days before first high-dose methotrexate course and then every 10 days) and four courses of intravenous high-dose methotrexate 8000 mg/m(2) (every 10 days) and then two courses of intravenous rituximab 375 mg/m(2) (day 1), cytarabine 3 g/m(2) (days 2 and 3), and thiotepa 40 mg/m(2) (day 3). 3 weeks after the last course, patients commenced intravenous HCT-ASCT (rituximab 375 mg/m(2) [day 1], carmustine 400 mg/m(2) [day 2], thiotepa 2 × 5 mg/kg [days 3 and 4], and infusion of stem cells [day 7]), irrespective of response status after induction. We restricted radiotherapy to patients without complete response after HCT-ASCT. The primary endpoint was complete response at day 30 after HCT-ASCT in all registered eligible patients who received at least 1 day of study treatment. This trial is registered at ClinicalTrials.gov, number NCT00647049.

FINDINGS

Between Jan 18, 2007, and May 23, 2011, we recruited 81 patients, of whom two (2%) were excluded, therefore we included 79 (98%) patients in the analysis. All patients started induction treatment; 73 (92%) commenced HCT-ASCT. 61 (77·2% [95% CI 66·1-86·6]) patients achieved a complete response. During induction treatment, the most common grade 3 toxicity was anaemia (37 [47%]) and the most common grade 4 toxicity was thrombocytopenia (50 [63%]). During HCT-ASCT, the most common grade 3 toxicity was fever (50 [68%] of 73) and the most common grade 4 toxicity was leucopenia (68 [93%] of 73). We recorded four (5%) treatment-related deaths (three [4%] during induction and one [1%] 4 weeks after HCT-ASCT).

INTERPRETATION

HCT-ASCT with thiotepa and carmustine is an effective treatment option in young patients with newly diagnosed primary CNS lymphoma, but further comparative studies are needed.

FUNDING

University Hospital Freiburg and Amgen.

Driving allotolerance: CAR-expressing Tregs for tolerance induction in organ and stem cell transplantation

Regulatory T cells (Tregs) modulate the function of a variety of immune cells and are critical for maintaining self-tolerance and preventing the development of autoimmune disease. Due to their ability to suppress effector T cells, Tregs have been increasingly explored for clinical use to suppress alloresponses. While this approach has been promising in preclinical models and early clinical trials, widespread clinical use of Tregs has been limited by the low number of these cells in the periphery and the unknown frequency of allo-responsive Tregs. In this issue of the JCI, MacDonald and colleagues transduced human Tregs with a chimeric antigen receptor (CAR) that targets the HLA class I molecule A2. These CAR-expressing T cells were readily activated via CAR stimulation and exerted potent immunosuppressive effects when stimulated in vitro. In a murine model of hematopoietic stem cell transplantation, CAR-modified Tregs were more effective in preventing the development of graft-versus-host disease compared with polyclonal Tregs. The results of this study lay the groundwork for the further evaluation of CAR-expressing Tregs in the prevention or treatment of transplant complications.

Impact of unbalanced minor route versus major route karyotypes at diagnosis on prognosis of CML

Major route additional cytogenetic aberrations (ACA) at diagnosis of chronic myeloid leukaemia (CML) indicate an increased risk of progression and shorter survival. Since major route ACA are almost always unbalanced, it is unclear whether other unbalanced ACA at diagnosis also confer an unfavourable prognosis. On the basis of 1348 Philadelphia chromosome-positive chronic phase patients of the randomized CML study IV, we examined the impact of unbalanced minor route ACA at diagnosis versus major route ACA on prognosis. At diagnosis, 1175 patients (87.2 %) had a translocation t(9;22)(q34;q11) and 74 (5.5 %) a variant translocation t(v;22) only, while a loss of the Y chromosome (-Y) was present in addition in 44 (3.3 %), balanced or unbalanced minor route ACA each in 17 (1.3 %) and major route ACA in 21 (1.6 %) cases. Patients with unbalanced minor route ACA had no significantly different cumulative incidences of complete cytogenetic remission or major molecular remission and no significantly different progression-free survival (PFS) or overall survival (OS) than patients with t(9;22), t(v;22), -Y and balanced minor route karyotypes. In contrast, patients with major route ACA had a shorter OS and PFS than all other groups (all pairwise comparisons to each of the other groups: p ≤ 0.015). Five-year survival probabilities were for t(9;22) 91.4 % (95 % CI 89.5-93.1), t(v; 22) 87 % (77.2-94.3), -Y 89.0 % (76.7-97.0), balanced 100 %, unbalanced minor route 92.3 % (72.4-100) and major route 52.2 % (28.2-75.5). We conclude that only major route, but not balanced or unbalanced minor route ACA at diagnosis, has a negative impact on prognosis of CML.