Alteration of Gut Microbiota Composition and Diversity in Acute and/or Chronic Graft-versus-Host Disease Following Hematopoietic Stem Cell Transplantation: A Prospective Cohort Study.

Changes in gut microbiome composition have been implicated in the pathogenesis of graft-versus-host disease (GvHD) after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Our objective was to explore the microbial abundance in patients with GvHD after allo-HSCT. We conducted a single-center, prospective study in patients who underwent allo-HSCT and developed grade II or higher acute GvHD and/or moderate or severe chronic GvHD, to explore the microbial abundance of taxa at the phylum, family, genus, and species level, and we utilized alpha and beta diversity indices to further describe our findings. We collected fecal specimens at -2 to +2 (T1), +11 to +17 (T2), +25 to +30 (T3), +90 (T4), and +180 (T5) days to assess changes in gut microbiota, with day 0 being the day of allo-HSCT. We included 20 allo-HSCT recipients in the study. Compared with timepoint T1, at timepoint T4 we found a significant decrease in the abundance of Proteobacteria phylum (14.22% at T1 vs. 4.07% at T4, p = 0.01) and Enterobacteriaceae family (13.3% at T1 vs. <0.05% at T4, p < 0.05), as well as a significant increase in Enterococcus species (0.1% at T1 vs. 12.8% at T4, p < 0.05) in patients who developed acute GvHD. Regarding patients who developed chronic GvHD after allo-HSCT, there was a significant reduction in the abundance of Eurobactereaceae family (1.32% at T1 vs. 0.53% at T4, p < 0.05) and Roseruria genus (3.97% at T1 vs. 0.09% at T4, p < 0.05) at T4 compared with T1. Alpha and beta diversity analyses did not reveal a difference in the abundance of bacteria at the genus level in GvHD patients at T4 compared with T1. Our study reinforces results from previous studies regarding changes in gut microbiota in patients with acute GvHD and provides new data regarding the gut microbiome changes in chronic GvHD. Future studies will need to incorporate clinical parameters in their analyses to establish their association with specific changes in gut microbiota in patients with GvHD after allo-HSCT.

Endothelial Injury Syndromes after Allogeneic Hematopoietic Stem Cell Transplantation: Angiopetin-2 as a Novel Predictor of the Outcome and the Role of Functional Autoantibodies against Angiotensin II Type 1 and Endothelin A Receptor.

Transplant-associated thrombotic microangiopathy (TMA) occurs in a significant percentage of patients after allogeneic stem cell transplantation (allo-SCT) and is associated with significant morbidity and mortality. The aim of the present study was to examine the association of serum angiopoetin-2 (Ang2) levels and the presence of antibodies against angiotensin II type 1 (AT1R) and ndothelin A Recreptor (ETAR) with the outcome of patients with TMA and/or graft-versus-host disease (GVHD) after allo-SCT. Analysis of our data showed that elevated serum Ang2 levels at the time of TMA diagnosis are significantly associated with increased non-relapse mortality and decreased overall survival. To our knowledge, this is the first study demonstrating an association between raised Ang2 levels and poor outcomes in patients with TMA. Antibodies against AT1R (AT1R-Abs) and ETAR (ETAR-Abs) were detected in 27% and 23% of the patients, respectively, but there was no association between the presence of autoantibodies and the outcome of patients with TMA. However, a significant finding was the strong positive correlation between the presence of AT1R-Abs with the occurrence of chronic fibrotic GVHD, such as scleroderma and cryptogenic organizing pneumonia, raising the possibility of the contribution of autoantibodies in the pathogenesis of fibrotic GVHD manifestations.

Soluble Urokinase-Type Plasminogen Activator Receptor (suPAR) and Growth Differentiation Factor-15 (GDF-15) Levels Are Significantly Associated with Endothelial Injury Indices in Adult Allogeneic Hematopoietic Cell Transplantation Recipients.

Hematopoietic stem cell transplantation-associated thrombotic microangiopathy (HSCT-TMA) and graft-versus-host disease (GvHD) represent life-threatening syndromes after allogeneic hematopoietic stem cell transplantation (allo-HSCT). In both conditions, endothelial dysfunction is a common denominator, and development of relevant biomarkers is of high importance for both diagnosis and prognosis. Despite the fact that soluble urokinase plasminogen activator receptor (suPAR) and growth differentiation factor-15 (GDF-15) have been determined as endothelial injury indices in various clinical settings, their role in HSCT-related complications remains unexplored. In this context, we used immunoenzymatic methods to measure suPAR and GDF-15 levels in HSCT-TMA, acute and/or chronic GVHD, control HSCT recipients, and apparently healthy individuals of similar age and gender. We found considerably greater SuPAR and GDF-15 levels in HSCT-TMA and GVHD patients compared to allo-HSCT and healthy patients. Both GDF-15 and suPAR concentrations were linked to EASIX at day 100 and last follow-up. SuPAR was associated with creatinine and platelets at day 100 and last follow-up, while GDF-15 was associated only with platelets, suggesting that laboratory values do not drive EASIX. SuPAR, but not GDF-15, was related to soluble C5b-9 levels, a sign of increased HSCT-TMA risk. Our study shows for the first time that suPAR and GDF-15 indicate endothelial damage in allo-HSCT recipients. Rigorous validation of these biomarkers in many cohorts may provide utility for their usefulness in identifying and stratifying allo-HSCT recipients with endothelial cell impairment.

Assessment of Endothelial Injury and Pro-Coagulant Activity Using Circulating Microvesicles in Survivors of Allogeneic Hematopoietic Cell Transplantation.

(1) Background: survivors of allogeneic hematopoietic cell transplantation (alloHCT) suffer from morbidity and mortality due to cardiovascular events. We hypothesized that vascular injury and pro-coagulant activity are evident in alloHCT survivors without existing alloHCT complications or relapse. (2) Methods: we enrolled consecutive adult alloHCT survivors without established cardiovascular disease and control individuals matched for traditional cardiovascular risk factors (January-December 2019). Circulating microvesicles (MVs) of different cellular origins (platelet, erythrocyte, and endothelial) were measured by a standardized flow cytometry protocol as novel markers of vascular injury and pro-coagulant activity. (3) Results: we recruited 45 survivors after a median of 2.3 (range 1.1-13.2) years from alloHCT, and 45 controls. The majority of patients suffered from acute (44%) and/or chronic (66%) graft-versus-host disease (GVHD). Although the two groups were matched for traditional cardiovascular risk factors, alloHCT survivors showed significantly increased platelet and erythrocyte MVs compared to controls. Within alloHCT survivors, erythrocyte MVs were significantly increased in patients with a previous history of thrombotic microangiopathy. Interestingly, endothelial MVs were significantly increased only in alloHCT recipients of a myeloablative conditioning. Furthermore, MVs of different origins showed a positive association with each other. (4) Conclusions: endothelial dysfunction and increased thrombotic risk are evident in alloHCT recipients long after alloHCT, independently of traditional cardiovascular risk factors. An apparent synergism of these pathophysiological processes may be strongly involved in the subsequent establishment of cardiovascular disease.

Isolated Extramedullary Relapse as a Poor Predictor of Survival after Allogeneic Hematopoietic Cell Transplantation for Acute Leukemia.

Limited and conflicting data exist on outcomes of patients with extramedullary relapses (EMRs) after allogeneic hematopoietic cell transplantation (allo-HCT) for acute leukemias. We retrospectively reviewed charts of consecutive allo-HCT recipients who underwent transplantation in our center with the indication of acute leukemia (July 1990 to July 2018). Incidences of isolated EMR (iEMR) and bone marrow relapse (BMR) were calculated using cumulative incidence (CI) analysis, with each and treatment-related mortality considered a competing risk. We studied 554 allo-HCT recipients for 1.8 years (range, .04 to 27.75). Ten-year CI of 10.5% for iEMR was associated only with advanced disease phase at transplantation, whereas 10-year CI of 34.8% for BMR was independently associated with pretransplant disease phase, lines of treatment, and fungal infections. Most iEMR and BMR patients (75% and 81%, respectively) received systemic treatment combined with local radiation for iEMR (26%) and donor lymphocyte infusions (16% and 28%, respectively) when feasible. Extensive chronic graft-versus-host disease (GVHD) was recorded in 47% of iEMR and 48% of BMR patients. Outcomes were poor both in iEMR (10-year overall survival [OS], 18.3%) and BMR (10-year OS, 19.1%). Independent predictors of OS were disease phase, type of donor, acute and chronic GVHD, fungal infections, iEMR, and BMR. In a large population with long-term follow-up, incidence of iEMR was relatively high, developed at the late post-transplant period, and was associated only with disease phase at transplantation. Furthermore, iEMR and BMR conferred similarly poor outcomes despite systemic treatment or extensive chronic GVHD.

Brentuximab vedotin in relapsed/refractory Hodgkin lymphoma. The Hellenic experience.

This retrospective study aimed to describe the Hellenic experience on the use of brentuximab vedotin (BV) in relapsed/refractory (R/R) Hodgkin lymphoma (HL) given within its indication. From June 2011 to April 2015, ninety-five patients with R/R HL, who received BV in 20 centers from Greece, were analyzed. Their median age was 33 years, and 62% were males. Sixty-seven patients received BV after autologous stem cell transplantation failure, whereas 28 patients were treated with BV without a prior autologous stem cell transplantation, due to advanced age/comorbidities or chemorefractory disease. The median number of prior treatments was 4 and 44% of the patients were refractory to their most recent therapy. The median number of BV cycles was 8 (range, 2-16), and the median time to best response was the fourth cycle. Fifty-seven patients achieved an objective response: twenty-two (23%), a complete response (CR), and 35 patients (37%), a partial, for an overall response rate of 60%. Twelve patients (13%) had stable disease, and the remaining twenty-six (27%) had progressive disease as their best response. At a median follow-up of 11.5 months, median progression-free survival and overall survival were 8 and 26.5 months, respectively. Multivariate analysis showed that chemosensitivity to treatment administered before BV was associated with a significantly increased probability of achieving response to BV (P = .005). Bulky disease (P = .01) and response to BV (P <.001) were significant for progression-free survival, while refractoriness to most recent treatment (P = .04), bulky disease (P = .005), and B-symptoms (P = .001) were unfavorable factors for overall survival. Among the 22 CRs, 5 remain in CR with no further treatment after BV at a median follow-up of 13 months. In conclusion, our data indicate that BV is an effective treatment for R/R HL patients even outside clinical trials. Whether BV can cure a fraction of patients remains to be seen.

Positive impact of brentuximab vedotin on overall survival of patients with classical Hodgkin lymphoma who relapse or progress after autologous stem cell transplantation: A nationwide analysis.

The outcome of patients with relapsed/refractory classical Hodgkin lymphoma (R/R cHL) after autologous stem cell transplantation (auto-SCT) is poor. Recently, the anti-CD30 monoclonal antibody-drug conjugate, brentuximab vedotin (BV), has shown remarkable activity in the setting of R/R cHL. In the pivotal phase II study, BV produced an overall response rate of 75% and a median progression-free survival of 6.7 months. Although these results have been reproduced by large registry studies, the impact of BV on the overall survival (OS) of patients with R/R cHL has not been addressed so far. The aim of this study was to examine the impact of BV on OS in the setting of post auto-SCT R/R cHL. Analysis was performed in a group of patients with R/R cHL after a previous auto-SCT reported in the Greek registry during the last 2 decades. By using a multivariate model and censoring patients at the time of subsequent allo-SCT or treatment with immune checkpoint inhibitors, we showed that treatment with BV in the posttransplant relapse setting has a positive impact on the outcome and results in significant improvement of OS. To our knowledge, this the first published study, addressing the impact of BV on the OS in the setting of posttransplant relapse.

Long-term outcomes of total body irradiation plus cyclophosphamide versus busulfan plus cyclophosphamide as conditioning regimen for acute lymphoblastic leukemia: a comparative study.

The role of total body irradiation (TBI) in allogeneic hematopoietic stem cell transplantation (HCT) for adult acute lymphoblastic leukemia (ALL) remains controversial. Therefore, we investigated long-term treatment outcomes of transplanted ALL patients aiming to identify prognostic factors and the impact of conditioning. We enrolled consecutive ALL patients transplanted from 1990 to 2016, following TBI- or busulfan (Bu)-based conditioning regimen. We studied 151 ALL patients transplanted in first complete remission (CR) (60), other CR (33), or relapsed/refractory disease (58) from sibling (87), and HLA-matched (42) or mismatched (17) unrelated and alternative donors (5). High-dose fractionated TBI-based conditioning was administered in 84. No differences were observed in baseline characteristics, except for disease stage at transplant, donor type, and graft source. With a follow-up of 19.0 (0.5-170.5) in TBI and 14.5 (1.2-319.1) months in non-TBI patients, there was no difference in acute (grades II-IV) or chronic GVHD, thrombotic microangiopathy, and bacterial or fungal infections. Only viral infections were significantly increased in the non-TBI group. There was no significant difference in the cumulative incidence (CI) of treatment-related or relapse mortality and disease-free or overall survival (OS). In the multivariate analysis, unfavorable pre-transplant predictors of OS were age (p = 0.024), advanced disease stage (p = 0.007), and female-to-male donor (p = 0.006). Interestingly, TBI patients younger than 40 years had significantly higher OS (55.1%, p = 0.023) and DFS (48.6%, p = 0.020). In conclusion, high-dose TBI is feasible in younger patients providing better survival. The choice between TBI- or Bu-conditioning regimens remains challenging.

Transplant-associated thrombotic microangiopathy: Incidence, prognostic factors, morbidity, and mortality in allogeneic hematopoietic cell transplantation.

Renewed interest has emerged in transplant-associated thrombotic microangiopathy (TA-TMA) with novel prognostic, diagnostic, and treatment algorithms. We aimed to investigate the incidence, prognostic factors, morbidity, and mortality of TA-TMA in allogeneic hematopoietic cell transplantation (HCT) recipients. We enrolled consecutive HCT recipients (1990-2017). Among 758 patients, 116 (15.5%) were diagnosed with TA-TMA. In the multivariate analysis, TBI-based conditioning, viral infections, acute and chronic GVHD remained independent predictors of TA-TMA. With a median follow-up of 23 (range 0.1-329) months, TA-TMA resulted in significantly lower overall survival (OS). In the multivariate analysis, TA-TMA remained an independent predictor of OS, along with relapse, acute, and chronic GVHD. Among 116 TA-TMA patients, 70 developed renal (56) and/or neurologic (26) dysfunction that would be necessary for TA-TMA diagnosis according to the Bone Marrow Transplant Clinical Trials Network criteria. TA-TMA patients with renal dysfunction showed increased rates of acute GVHD, but no difference in OS compared to patients without renal dysfunction. However, neurologic dysfunction resulted in significantly lower OS. In conclusion, TA-TMA is associated with increased morbidity and mortality in allogeneic transplant recipients. Successful prevention and treatment strategies of infections and GVHD need to be timely employed to improve survival in this complex setting.

Open-Label Randomized Controlled Study of Ciprofloxacin vs Rifaximin as Neutropenia Prophylaxis in Allogeneic Hematopoietic Stem Cell Transplantation.

Loss of microbiota diversity has been clearly associated with poor outcomes in the allogeneic hematopoietic stem cell transplantation setting. However, the choice of the optimal antibiotic prophylaxis during the pre-engraftment phase remains unclear. We designed a prospective randomized study to compare our standard-of-care neutropenia prophylaxis (ciprofloxacin) with rifaximin. We enrolled 38 consecutive adult patients who underwent allogeneic hematopoietic stem cell transplantation setting and were randomly assigned to receive ciprofloxacin (20 patients) or rifaximin (18 patients) at day -1. Pretransplant and transplant characteristics did not differ between groups. Cumulative incidence (CI) of acute graft-vs-host disease grade II to IV and moderate/severe chronic graft-vs-host disease was similar in both groups. With a median follow-up of 13.2 months (range, 6.8-30.2) in surviving patients, the 1-year CI of relapse was 20.8% in ciprofloxacin vs 17.8% in rifaximin (P = .616). Importantly, the 1-year CI of treatment-related mortality was significantly reduced in the ciprofloxacin group (10.2% vs 27.8%, P = .032), leading to higher 1-year overall survival (88.9% vs 74.6%, P = .038). In Cox-regression multivariate analysis, antibiotic prophylaxis remained the only predictor of overall survival, independently of donor type, disease risk index, and moderate/severe chronic graft-vs-host disease. Further studies are needed to assess the effects on microbiota diversity and confirm these outcomes.

Risk Factors, Prevalence, and Outcomes of Invasive Fungal Disease Post Hematopoietic Cell Transplantation and Cellular Therapies: A Retrospective Monocenter Real-Life Analysis.

(1) Background: Autologous, allogeneic hematopoietic cell transplantation (HCT) and other cellular therapies, including CAR T cell and gene therapy, constitute a cornerstone in the management of various benign and malignant hematological disorders. Invasive fungal infections (IFD) remain a significant cause of morbidity and mortality in HCT recipients. Therefore, we investigated the prevalence and risk factors of IFD following HCT and other cellular therapies in an era of novel antifungal prophylaxis. (2) Methods: In this study, we retrospectively enrolled adult HCT recipients who were treated at our JACIE-accredited center according to standard operating procedures over the last decade (2013-2022). (3) Results: 950 patients who received cellular therapies were studied. None of the 19 CAR T cell and neither of the two gene therapy recipients developed IFD whereas 3/456 autologous HCT recipients who suffered from primary refractory/relapsed lymphomas presented with probable IFD. Overall, 11 patients who received allogeneic HCT experienced probable IFD, possible IFD was found in 31/473, and IFD was proven in 10/473. A second IFD episode was present in three patients. Four-year OS was significantly lower in proven compared to probable IFD (p = 0.041) and was independently associated with HCT-CI (p = 0.040) and chronic GVHD (p = 0.045). (4) Conclusions: In this real-world cohort, the prevalence of proven and probable IFD in an era of novel antifungal prophylaxis was found to be relatively low. However, IFDs were associated with poor outcomes for patients who received allogeneic HCT.

SARS-CoV-2-specific T cell therapy for severe COVID-19: a randomized phase 1/2 trial.

Despite advances, few therapeutics have shown efficacy in severe coronavirus disease 2019 (COVID-19). In a different context, virus-specific T cells have proven safe and effective. We conducted a randomized (2:1), open-label, phase 1/2 trial to evaluate the safety and efficacy of off-the-shelf, partially human leukocyte antigen (HLA)-matched, convalescent donor-derived severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-specific T cells (CoV-2-STs) in combination with standard of care (SoC) in patients with severe COVID-19 compared to SoC during Delta variant predominance. After a dose-escalated phase 1 safety study, 90 participants were randomized to receive CoV-2-ST+SoC (n = 60) or SoC only (n = 30). The co-primary objectives of the study were the composite of time to recovery and 30-d recovery rate and the in vivo expansion of CoV-2-STs in patients receiving CoV-2-ST+SoC over SoC. The key secondary objective was survival on day 60. CoV-2-ST+SoC treatment was safe and well tolerated. The study met the primary composite endpoint (CoV-2-ST+SoC versus SoC: recovery rate 65% versus 38%, P = 0.017; median recovery time 11 d versus not reached, P = 0.052, respectively; rate ratio for recovery 1.71 (95% confidence interval 1.03-2.83, P = 0.036)) and the co-primary objective of significant CoV-2-ST expansion compared to SοC (CoV-2-ST+SoC versus SoC, P = 0.047). Overall, in hospitalized patients with severe COVID-19, adoptive immunotherapy with CoV-2-STs was feasible and safe. Larger trials are needed to strengthen the preliminary evidence of clinical benefit in severe COVID-19. EudraCT identifier: 2021-001022-22 .

Pneumomediastinum as a rare complication in an immunosuppressed patient with emphysematous cystitis.

The extravesical spread of gas into the extraperitoneal space is an unusual complication of emphysematous cystitis and rarely, can reach remote areas of the body. Herein, we present the case of an immunosuppressed woman with emphysematous cystitis and extensive spread of extraperitoneal free gas up to the mediastinum.

A non-interventional study of microcirculation dynamics in allogeneic hematopoietic cell transplantation survivors compared to controls: evidence of impaired microvascular response regardless of conventional cardiovascular risk factors.

Allogeneic hematopoietic cell transplantation (alloHCT) survivors have been recently recognized as patients at increased cardiovascular risk. We hypothesized that vascular function remains impaired in alloHCT survivors free of graft-versus-host-disease or relapse. We enrolled consecutive adult alloHCT survivors and non-HCT control individuals (January 2019-March 2020), matched for traditional cardiovascular risk factors. Microvascular dysfunction was dynamically assessed in real time by Laser Speckle Contrast Analysis (LASCA). Carotid-femoral pulse-wave velocity (PWV) and carotid intima media thickness (IMT) were assessed as surrogate markers of cardiovascular disease. We studied 75 patients after a median of 3.2 (range 2.1-4.9) years from alloHCT, who had suffered from grade 2 to 3 acute (20%) and/or moderate/severe chronic GVHD (42%), and 75 controls. Although traditional cardiovascular risk factors and surrogate markers of cardiovascular disease did not differ between groups, alloHCT survivors showed significantly impaired microvascular function (baseline and peak flux, time to peak, base to peak and base to occlusion change). LASCA indices were also independently associated with alloHCT. Our study shows for the first-time impaired microcirculation dynamics in alloHCT survivors, independently of cardiovascular risk factors. Additional studies are needed to address the role of novel markers in cardiovascular risk prediction, along with effects of disease type, phase, and pre-transplant treatments.

Predictors of Transplant-Associated Thrombotic Microangiopathy in Patients With Overlap or Chronic Graft-vs-Host-Disease.

BACKGROUND: Recent data suggest that novel biologic agents are associated with increased risk of thrombotic microangiopathy (TMA). Ruxolitinib, an approved treatment for graft-vs-host-disease (GVHD), has been associated with thrombocytopenia of unclear etiology. METHODS: We investigated factors and outcomes associated with transplant-associated thrombotic microangiopathy (TA-TMA) in patients with GVHD. We retrospectively enrolled consecutive allogeneic hematopoietic cell transplantation recipients with overlap or chronic GVHD at our Joint Accreditation Committee ISCT-Europe & EBMT-accredited unit (January 2016-June 2019). Ruxolitinib has been administered off-label since 2016. RESULTS: Among 160 patients with GVHD, 18 were diagnosed with TA-TMA. TA-TMA developed at a median of 150 posttransplant days (range, 98-3013). Among pre- and posttransplant factors, TA-TMA was associated only with ruxolitinib administration and severe GVHD. Interestingly, these 2 variables did not correlate with each other. In the multivariate analysis, both were independent predictors of TA-TMA. Time-dependent analysis confirmed ruxolitinib's association with TA-TMA. With a follow-up of 38.4 months (4.6-83.9) in surviving patients, 5-year overall survival was 52.9%, independently predicted by TA-TMA, severe acute GVHD, and CD34+ cells infused. Ruxolitinib was not associated with survival outcomes. CONCLUSIONS: Our data suggest that ruxolitinib and GVHD severity are associated with TA-TMA. Given the expanding use of ruxolitinib in GVHD and ongoing trials on chronic GVHD, further studies are warranted to confirm these findings.

Survival Advantage of Treosulfan Plus Fludarabine Before Allogeneic Hematopoietic Cell Transplantation for Older or Comorbid Patients With Myeloid Malignancies.

We have previously shown an advantage of a myeloablative conditioning regimen with reduced toxicity (Fludarabine 150 mg/m2, Treosulfan 42 g/m2, FluTreo) compared to a reduced-intensity regimen. We aimed to determine long-term safety and efficacy of FluTreo. We prospectively studied consecutive patients who received FluTreo in our center (2014-2019) on the basis of age (≥50 years), hematopoietic cell transplantation comorbidity index (HCT-CI) ≥2, or both. FluTreo recipients were then compared to a historical control group. We studied 68 FluTreo recipients, with a median age of 58.5 years and HCT-CI of 3. We calculated cumulative incidence (CI) of acute (grade 2-4) and moderate/severe chronic graft-versus-host disease (GVHD) (29.9% and 25%, respectively). The 3-year CI of treatment-related mortality was 19.1%, associated only with acute GVHD (P < .001). With a median follow-up of 27.3 (range 5.7-84.5) months in surviving patients, the 3-year overall survival (OS) was 56.6%, and disease-free survival (DFS) was 54.9%. Median survival has not yet been reached. Among pretransplantation and transplantation factors, only HCT-CI was associated with DFS and OS (P = .022 and P = .043, respectively). FluTreo recipients aged ≥50 with HCT-CI ≤ 2 had favorable DFS and OS compared with patients aged ≥50 with HCT-CI ≤2 after myeloablative conditioning. Our real-world study confirms that HCT with FluTreo expands the transplant population with favorable outcomes compared to previously used conditions. The choice of HCT in patients of a rather older age and comorbidity index needs to be revisited.

Risk Factors and Outcomes of Klebsiella pneumoniae Infection Before and After Allogeneic Hematopoietic Cell Transplantation.

Objectives: Klebsiella pneumoniae carbapenemase (KPC)-producing K. pneumoniae (KPC-Kp) emerge as a major healthcare concern worldwide. Despite the significance of infections before and after allogeneic hematopoietic cell transplantation (alloHCT), the burden of KP infections has not been extensively evaluated. Methods: We studied the incidence, risk factors, and outcomes of consecutive alloHCT recipients with Kp isolates before and after alloHCT. Results: Among 424 patients who underwent alloHCT in 2008-2018, we studied two groups: those with Kp isolates before (group 1, 52 patients) and those with Kp isolates after alloHCT (group 2, 66 patients). prE-transplant infections were associated with post-transplant infections (p = 0.010), despite secondary prophylaxis. KPC-Kp was isolated in 29% of group 1, and 80% of group 2. Both groups were characterized by a significant burden of moderate-severe acute graft- vs.-host disease (GVHD) [cumulative incidence (CI) of 44.5 and 61.9%, respectively] and severe chronic (CI of 56.7 and 61.9%). Kp infections and GVHD were independent predictive factors of treatment-related mortality (TRM) in both groups. Conclusions: Our study highlights the significant impact of Kp infections on TRM, with GVHD consisting an important underlying factor. As prophylactic measures did not improve rates of post-transplant infections, innovative interventions need to be further investigated to address this major healthcare concern.

The Role of Low-dose Anti-thymocyte Globulin as Standard Prophylaxis in Mismatched and Matched Unrelated Hematopoietic Peripheral Stem Cell Transplantation for Hematologic Malignancies.

INTRODUCTION: Anti-thymocyte globulin (ATG)-based immunosuppressive therapy is often used in allogeneic hematopoietic cell transplantation to reduce incidence and severity of graft-versus-host disease (GVHD). PATIENTS AND METHODS: In our observational study, ATG (rabbit, Thymoglobulin; Sanofi, 5 mg/kg) was administered as a standardized part of the conditioning in 97 patients with a median age of 34 years (range, 14-58 years), allotransplanted for hematologic malignancies from matched (8/8; n = 52) and allele or antigen mismatched (7/8; n = 43 and 6/8; n = 2) unrelated donors. RESULTS: Five-year overall survival (OS) was 46.9%, disease-free survival was 46.5%, and treatment-related mortality was 20.6%, with a median follow-up of 29 months (range, 1-145 months). Acute GVHD (grade ≥ II) cumulative incidence was 26.9% in matched versus 50.5% in mismatched patients (P = .060), whereas extensive chronic GVHD was 45.6% versus 50%, respectively (P = .310). Five-year OS was 62.2% for the matched patients and 27.9% for the mismatched patients (P = .003) owing to a higher treatment-related mortality rate in mismatched patients (P = .032). In multivariate analysis including age, gender, time until transplantation, disease phase, mismatched donor, ABO mismatch, number of CD34+ infused, acute and chronic GVHD, the significant unfavorable factors for OS were HLA mismatch and advanced disease phase. CONCLUSION: A relatively low-dose ATG is effective in acute GVHD prophylaxis, leading to promising survival rates in matched transplants. Further comparative studies with adjusted ATG dose depending on Human leukocyte antigen disparity or alternative donors are warranted.