Remission of relapsed/refractory classical Hodgkin lymphoma induced by brentuximab vedotin and pembrolizumab combination after allogeneic hematopoietic stem cell transplantation: a case report

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a potentially curative treatment option for patients with highly chemorefractory Hodgkin lymphoma (HL). The CD30-targeting antibody-drug conjugate Brentuximab-Vedotin (BV) and programmed cell death protein-1 (PD-1) blocking agents have demonstrated clinical activity with durable responses in relapsed/refractory (r/r) HL. However, patients with a history of allo-HSCT were frequently excluded from clinical trials due to concerns about the risk of graft-versus-host disease (GVHD). We report the clinical history of a patient with refractory classical HL who underwent two allo-HSCTs (first from matched unrelated and second from haploidentical donor) after relapsing on BV and nivolumab and for whom durable remission was finally obtained using BV-pembrolizumab combination for relapse after haploidentical HSCT. Such treatment was associated with the onset of GVHD after only two cycles which led to treatment discontinuation. However, the side effects were rapidly controlled, and after 2 years of follow-up, the patient is still in remission. Our data support the feasibility and efficacy of combining PD-1 blockade with BV to enhance the graft-versus-lymphoma effect after allo-HSCT.

Revisiting Cytomegalovirus Serology in Allogeneic Hematopoietic Cell Transplant Recipients

BACKGROUND

Allogeneic hematopoietic cell transplant recipients (allo-HCTRs) with positive cytomegalovirus (CMV) serology may have false-positive results due to blood product transfusion-associated passive immunity.

METHODS

This single-center cohort study included allo-HCTRs with negative baseline (at malignancy diagnosis) CMV serology and indeterminate/low-positive (CMV IgG titer, ≥0.6-<50 U/mL) pretransplant CMV serology with negative pretransplant plasma CMV DNAemia. The CMV status of those patients was reclassified from R+ to R- (CMVR- reclassification group). We compared those patients to allo-HCTRs with negative (CMV IgG titer <0.6 U/mL) pretransplant CMV IgG (CMVR- group). We describe the number and type of patients whose pretransplant CMV status was reclassified from indeterminate/positive to negative. We reviewed all plasma CMV DNAemia tests performed during the first 6 months posttransplant in both groups to assess the safety of this approach.

RESULTS

Among 246 (84.5%) of 291 transplanted patients identified as CMVR+ pretransplant, 60 (24.4%) were reclassified from CMV serology indeterminate (N:10)/low-positive (N:50) to R-. Only 1 of 60 patients (1.67%) in the CMVR- reclassification group versus 3 of 44 (6.8%; P = .30) in the CMVR- group developed CMV DNAemia during the follow-up period. There were no significant differences in the number of CMV DNAemia tests performed, CMV DNAemia range, and time posttransplant between the 2 groups.

CONCLUSIONS

One of 4 allo-HCT CMVR+ may be falsely flagged as R+, with significant impact on donor selection and prophylaxis administration. A 2-step approach including CMV serology testing at hematologic malignancy diagnosis in allo-HCT candidates and careful review of pretransplant CMV IgG titers may help correctly classify CMV serology status.

[Second allogeneic (update). Guidelines from the Francophone Society of Bone Marrow Transplantation and Cellular Therapy (SFGM-TC)]

Relapse after allogeneic hematopoietic cell transplantation (allo-HCT) remains a major concern because it is associated with poor survival. A second allo-HCT is a valid option in this situation. During the 13th annual harmonization workshops of the francophone Society of bone marrow transplantation and cellular therapy (SFGM-TC), a designated working group reviewed the literature in order to update the second allo-HCT recommendations elaborated during the previous workshop (2016). The main indication for a second allo-HCT remains relapse of initial hematologic malignancy. Disease status; complete remission (CR), and relapse time after the first allo-HCT>6 months impact positively the overall survival of patients after the second allo-HCT. Donor change is a valid option, particularly if there is HLA loss on leukemic cells after a first haploidentical or following a mismatched allo-HCT is documented. Reduced intensity conditioning is recommended, while a sequential protocol is a reasonable option in patients with proliferative disease. A post-transplant maintenance strategy after hematological recovery is recommended as soon as day 60, even if the immunosuppressive treatment has not yet been stopped. Hypomethylating agents, and targeted therapies such as anti FLT3, anti BCL2, anti-IDH1/2, TKI, anti-TP53, anti-CD33, anti-CD19, anti-CD22, anti-CD30, check point inhibitors, and CAR-T cells can be used as a bridge to transplant or as an alternative treatment to the second allo-HCT.

Hematopoietic cell transplantation and cellular therapies in Switzerland. Evolution over 25 years. A report from the stem cell transplantation and cellular therapies working groups of the SBST 1997-2021

The Swiss Blood Stem Cell Transplantation and Cellular Therapy Group (SBST) leads a mandatory national registry for all hematopoietic stem cell transplants (HCT) and cellular therapies. After 25 years, information was available for 11,226 patients receiving an HCT (4031 allogeneic and 7195 autologous), including 925 pediatric patients. We compared patient characteristics and outcome by quinquennia 1997-2001, 2002-2006, 2007-2011, 2012-2016, and 2017-2021. There were numerous changes over time. Allogeneic transplant recipients became older (median age 33.7 vs. 54.3) and had more frequently unrelated donors and reduced intensity conditioning in later quinquennia. Similarly, age increased for recipients of autologous HCT (median 48.3 vs. 59.9). We did not see a significant drop in transplant activity during the SARS-CoV-2 pandemic. Analysis of outcome showed overall survival (relative risk (RR) of death 0.664 (0.529-0.832) and progression free survival (RR 0.708 (0.577-0.870) being improved over time comparing the latest to the first quinquennium adjusting for risk factors. Non-relapse mortality decreased in recipients of allogeneic HCT (RR: 0.371 (0.270-0.509)) over time but relapse risks did not. Outcome of autologous HCT improved as well across quinquennia, this improvement was mainly due to decreased relapse risks (RR 0.681 (0.597-0.777)), possibly related to maintenance treatment or rescue treatment for relapse mainly in myeloma patients. Cellular therapies other than allogeneic or autologous HCT, particularly chimeric antigen receptor T-cells (CAR-T) treatment have started to increase after 2019, year of approval of the first commercial CAR-T product in Switzerland. Data on chimeric antigen receptor T-cell treatment are too early for comparative analyses. Detailed analyses of changes over time are presented. This study includes all HCTs, and cellular therapies, data useful for quality assurance programs, health care cost estimation and benchmarking. Between 50% and 60% of patients are long-term survivors after both types of HCT, indicating growing populations of surviving patients requiring long-term care.

Hepatitis E Virus Infection Epidemiology in Recipients of Allogeneic Hematopoietic Cell Transplant

Among 292 recipients of allogeneic hematopoietic cell transplant (2018-2022), 64 (21.9%) tested positive for anti-hepatitis E virus (HEV) immunoglobulin G. Among 208 recipients tested by plasma/serum HEV polymerase chain reaction (2012-2022), 3 (1.4%) primary HEV infections were diagnosed; in 1 patient, plasma HEV polymerase chain reaction relapsed positive for 100 days. HEV infection remains rare albeit associated with persistent viral replication.

Routine Infectious Disease Consultation Prior to an Allogeneic Hematopoietic Cell Transplant

Background

A transplant infectious disease (TID) assessment is essential to select recipients for an allogeneic hematopoietic cell transplant (HCT) and tailor prophylactic and empirical treatment recommendations.

Methods

We performed a retrospective single-center study to describe our model of care based on a routine TID consultation prior to an allogeneic HCT between 2018 and 2022 in 292 adult (≥18-year-old) consecutive patients. We describe the performance of a TID consultation, arbitrarily defined as major (HCT postponement, procedure, cytomegalovirus [CMV] recipient serology reinterpretation) and minor interventions.

Results

Overall, 765 interventions were observed in 257 of 292 (88%) patients: 88 of 765 (11.5%) major and 677 of 765 (88.5%) minor interventions. Among major interventions, HCT was postponed in 8 of 292 (2.7%) patients and a procedure was requested in 18 of 292 (6.2%) patients. The CMV recipient serostatus was changed from indeterminate/low-titer positive to negative in 60 of 292 (20.5%) patients. Among 677 minor interventions, there were 68 (8.8%) additional consultations with other services requested, 260 (33.7%) additional diagnostic tests requested, 102 (13.2%) additional treatments recommended, 60 (7.8%) non-CMV serology reinterpretations performed, 115 (14.9%) deviations from routine anti-infective prophylaxis, and 72 (9.3%) deviations from routine empirical antibiotic treatment recommendations in case of neutropenic fever.

Conclusions

We are proposing a structured, clearly defined, and comprehensive pretransplant checklist for an effective assessment of infectious disease risks and complications prior to an allogeneic HCT. Further studies or experiences like ours could help to define a global strategy or new models of care to be implemented in HCT centers in the future.

Salvage Treatment of Refractory HSV Oral Lesions with Pritelivir in Allogeneic Hematopoietic Cell Transplant Recipients

We present two allogeneic hematopoietic cell transplantation recipients (HCTr) treated with pritelivir for acyclovir-resistant/refractory (r/r) HSV infection based on the expanded access program of the pritelivir manufacturer. Outpatient treatment with pritelivir was administered, with partial response by week 1 of treatment and complete response by week 4 of treatment in both patients. No adverse events were noted. Pritelivir appears to be an effective and safe option for the management of acyclovir-r/r HSV infections in highly immunocompromised patients in an outpatient setting.

Longitudinal Detection of Twenty DNA and RNA Viruses in Allogeneic Hematopoietic Stem Cell Transplant Recipients Plasma

Metagenomics revealed novel and routinely overlooked viruses, representing sources of unrecognized infections after allogeneic hematopoietic stem cell transplantation (allo-HSCT). We aim to describe DNA and RNA virus prevalence and kinetics in allo-HSCT recipients' plasma for one year post HSCT. We included 109 adult patients with first allo-HSCT from 1 March 2017 to 31 January 2019 in this observational cohort study. Seventeen DNA and three RNA viral species were screened with qualitative and/or quantitative r(RT)-PCR assays using plasma samples collected at 0, 1, 3, 6, and 12 months post HSCT. TTV infected 97% of patients, followed by HPgV-1 (prevalence: 26-36%). TTV (median 3.29 × 10⁵ copies/mL) and HPgV-1 (median 1.18 × 10⁶ copies/mL) viral loads peaked at month 3. At least one Polyomaviridae virus (BKPyV, JCPyV, MCPyV, HPyV6/7) was detected in >10% of patients. HPyV6 and HPyV7 prevalence reached 27% and 12% at month 3; CMV prevalence reached 27%. HSV, VZV, EBV, HHV-7, HAdV and B19V prevalence remained <5%. HPyV9, TSPyV, HBoV, EV and HPg-V2 were never detected. At month 3, 72% of patients had co-infections. TTV and HPgV-1 infections were highly prevalent. BKPyV, MCPyV and HPyV6/7 were frequently detected relative to classical culprits. Further investigation is needed into associations between these viral infections and immune reconstitution or clinical outcomes.

CMV infection after letermovir primary prophylaxis discontinuation in allogeneic hematopoietic cell transplant recipients

In this single-center study of 61 allogeneic hematopoietic cell transplant (HCT) recipients receiving letermovir primary CMV-prophylaxis for the first 100 days, we report 23% incidence of clinically significant CMV infection during the first 100 days after letermovir discontinuation, predominately in haploidentical HCT recipients, without any associations with CMV-DNAemia under letermovir.

Real-world experience of sorafenib maintenance after allogeneic hematopoietic stem cell transplantation for FLT3-ITD AML reveals high rates of toxicity-related treatment interruption

Sorafenib significantly improves survival of FLT3-ITD mutated AML patients when used as a post-allogeneic HSCT maintenance. Importantly, clinical trials reported a low rate of toxicities requiring sorafenib discontinuation. The aim of our analysis was to evaluate the real-world experience in patients treated with post-allogeneic HSCT sorafenib maintenance therapy for FLT3-ITD AML with a particular focus on tolerability and toxicity-related treatment interruption. We conducted a single-center retrospective study on 30 FLT3-ITD AML patients undergoing allogeneic HSCT in complete remission between 2017 and 2020 and who received sorafenib maintenance. 26 patients (87%) experienced toxicities leading to dose reduction (n=9) or direct interruption (n=17). Average time on sorafenib was 125 days (range 1-765). Most common toxicities were skin, gastrointestinal, and hematologic. Among patients who had a dose reduction, 4 eventually interrupted the drug and 5 were able to continue. Among patients who interrupted sorafenib because of toxicities, 7 were re-challenged with good tolerance in 3 cases. Overall, 18 patients (60% of the entire cohort) definitively discontinued sorafenib because of toxicities. 14 patients were thereafter switched to midostaurin. Importantly, with a median follow-up of 12 months, the median overall survival was not reached suggesting a positive impact of sorafenib maintenance despite the high rates of treatment interruption. In conclusion, our real-world analysis reveals high rates of toxicity-related interruption of sorafenib maintenance after allogeneic HSCT. Interestingly, our results suggest the feasibility of re-challenging with sorafenib and/or of switching to other maintenance approaches in case of intolerance.

Atypical pulmonary phaeohyphomycosis due to Aureobasidium spp. - case report and brief literature review

We report on a case of probable invasive Auerobasidium spp. pulmonary infection in a patient with myelodysplastic syndrome. The patient was successfully treated with liposomal amphotericin B monotherapy, with transition to orally administered isavuconazole. This case shows an atypical initial radiological presentation with diffuse ground-glass opacities, as previously demonstrated in cases of Aureobasidium spp. hypersensitivity pneumonitis. Moreover this case further highlights the difficulties associated with the diagnosis and complexity in the management of Aureobasidium spp. infections.

Very severe immune thrombocytopenia following SARS-CoV-2 vaccination requiring splenectomy: a case report

Background

Some conventional vaccines have been recognized as a cause of secondary immune thrombocytopenia (ITP). According to recent publications, mRNA vaccines are probably associated with an increased risk of ITP.

Case presentation

Our patient developed severe ITP one week after the second dose of COVID-19 mRNA vaccine. Medical management was not effective, requiring splenectomy to obtain sustained remission.

Conclusion

Considering the temporality and immunological hypothesis, we consider the vaccine to be the trigger of this ITP. To our knowledge, our case is, to date, the most severe case of ITP reported following SARS-CoV-2 vaccination and could help for the therapeutic management of similar patients.

Invasive Mold Infections in Allogeneic Hematopoietic Cell Transplant Recipients in 2020: Have We Made Enough Progress?

Background

Despite progress in diagnostic, prevention, and treatment strategies, invasive mold infections (IMIs) remain the leading cause of mortality in allogeneic hematopoietic cell transplant (allo-HCT) recipients.

Methods

We describe the incidence, risk factors, and mortality of allo-HCT recipients with proven/probable IMI in a retrospective single-center 10-year (01/01/2010–01/01/2020) cohort study.

Results

Among 515 allo-HCT recipients, 48 (9.3%) patients developed 51 proven/probable IMI: invasive aspergillosis (IA; 34/51, 67%), mucormycosis (9/51, 18%), and other molds (8/51, 15%). Overall, 35/51 (68.6%) breakthrough IMIs (bIMIs) were identified: 22/35 (62.8%) IA and 13/35 (37.1%) non-IA IMI. One-year IMI cumulative incidence was 7%: 4.9% and 2.1% for IA and non-IA IMI, respectively. Fourteen (29.2 %), 10 (20.8%), and 24 (50.0%) patients were diagnosed during the first 30, 31–180, and >180 days post-HCT, respectively. Risk factors for IMI included prior allo-HCT (sub hazard ratio [SHR], 4.06; P = .004) and grade ≥2 acute graft-vs-host disease (aGvHD; SHR, 3.52; P < .001). All-cause 1-year mortality was 33% (170/515): 48% (23/48) and 31.5% (147/467) for patients with and without IMI (P = .02). Mortality predictors included disease relapse (hazard ratio [HR], 7.47; P < .001), aGvHD (HR, 1.51; P = .001), CMV serology–positive recipients (HR, 1.47; P = .03), and IMI (HR, 3.94; P < .001). All-cause 12-week mortality for patients with IMI was 35.4% (17/48): 31.3% (10/32) for IA and 43.8% (7/16) for non-IA IMI (log-rank P = .47). At 1 year post–IMI diagnosis, 70.8% (34/48) of the patients were dead.

Conclusions

IA mortality has remained relatively unchanged during the last 2 decades. More than two-thirds of allo-HCT recipients with IMI die by 1 year post–IMI diagnosis. Dedicated intensified research efforts are required to further improve clinical outcomes.

Human pegivirus-1 replication influences NK cell reconstitution after allogeneic haematopoietic stem cell transplantation

Introduction

Human pegivirus-1 (HPgV-1) is a so-called commensal virus for which no known associated organ disease has been found to date. Yet, it affects immune-reconstitution as previously studied in the HIV population, in whom active co-infection with HPgV-1 can modulate T and NK cell activation and differentiation leading to a protective effect against the evolution of the disease. Little is known on the effect of HPgV-1 on immune-reconstitution in allogeneic hematopoietic stem cell transplant (allo-HSCT) recipients, a patient population in which we and others have previously reported high prevalence of HPgV-1 replication. The aim of this study was to compare the immune reconstitution after allo-HSCT among HPgV-1-viremic and HPgV-1-non-viremic patients.

Methods

Within a cohort study of 40 allo-HSCT patients, 20 allo-HSCT recipients positive in plasma sample for HPgV-1 by rRT-PCR during the first year (1, 3, 6, 12 months) after transplantation were matched with 20 allo-HSCT recipients negative for HPgV-1. T and NK cell reconstitution was monitored by flow cytometry in peripheral blood samples from allo-HSCT recipients at the same time points.

Results

We observed no significant difference in the absolute number and subsets proportions of CD4 and CD8 T cells between patient groups at any analysed timepoint. We observed a significantly higher absolute number of NK cells at 3 months among HPgV-1-viremic patients. Immunophenotypic analysis showed a significantly higher proportion of CD56^bright NK cells mirrored by a reduced percentage of CD56^dim NK cells in HPgV-1-positive patients during the first 6 months after allo-HSCT. At 6 months post-allo-HSCT, NK cell phenotype significantly differed depending on HPgV-1, HPgV-1-viremic patients displaying NK cells with lower CD16 and CD57 expression compared with HPgV-1-negative patients. In accordance with their less differentiated phenotype, we detected a significantly reduced expression of granzyme B in NK cells in HPgV-1-viremic patients at 6 months.

Discussion

Our study shows that HPgV-1-viremic allo-HSCT recipients displayed an impaired NK cell, but not T cell, immune-reconstitution compared with HPgV-1-non-viremic patients, revealing for the first time a potential association between replication of the non-pathogenic HPgV-1 virus and immunomodulation after allo-HSCT.

Outcomes and toxicity of allogeneic hematopoietic cell transplantation in chronic myeloid leukemia patients previously treated with second-generation tyrosine kinase inhibitors: a prospective non-interventional study from the Chronic Malignancy Working Party of the EBMT

Allogeneic hematopoietic cell transplantation (allo-HCT) remains a treatment option for patients with chronic myeloid leukemia (CML) who fail to respond to tyrosine kinase inhibitors (TKIs). While imatinib seems to have no adverse impact on outcomes after transplant, little is known on the effects of prior use of second-generation TKI (2GTKI). We present the results of a prospective non-interventional study performed by the EBMT on 383 consecutive CML patients previously treated with dasatinib or nilotinib undergoing allo-HCT from 2009 to 2013. The median age was 45 years (18-68). Disease status at transplant was CP1 in 139 patients (38%), AP or >CP1 in 163 (45%), and BC in 59 (16%). The choice of 2GTKI was: 40% dasatinib, 17% nilotinib, and 43% a sequential treatment of dasatinib and nilotinib with or without bosutinib/ponatinib. With a median follow-up of 37 months (1-77), 8% of patients developed either primary or secondary graft failure, 34% acute and 60% chronic GvHD. There were no differences in post-transplant complications between the three different 2GTKI subgroups. Non-relapse mortality was 18% and 24% at 12 months and at 5 years, respectively. Relapse incidence was 36%, overall survival 56% and relapse-free survival 40% at 5 years. No differences in post-transplant outcomes were found between the three different 2GTKI subgroups. This prospective study demonstrates the feasibility of allo-HCT in patients previously treated with 2GTKI with a post-transplant complications rate comparable to that of TKI-naive or imatinib-treated patients.

Frequency and causes of antifungal treatment changes in allogeneic haematopoïetic cell transplant recipients with invasive mould infections

Background

Antifungal treatment duration and changes for invasive mould infections (IMI) have been poorly described.

Methods

We performed a 10‐year cohort study of adult (≥18‐year‐old) allogeneic haematopoietic cell transplant recipients with proven/probable IMI to describe the duration and changes of antifungal treatment. All‐cause‐12‐week mortality was described.

Results

Sixty‐one patients with 66 IMI were identified. Overall treatment duration was 157 days (IQR: 14–675) and 213 (IQR: 90–675) days for patients still alive by Day 84 post‐IMI diagnosis. There was at least one treatment change in 57/66 (86.4%) cases: median 2, (IQR: 0–6, range:0–8). There were 179 antifungal treatment changes due to 193 reasons: clinical efficacy (104/193, 53.9%), toxicity (55/193, 28.5%), toxicity or drug interactions resolution (15/193, 7.8%) and logistical reasons (11/193, 5.7%) and 15/193 (7.8%) changes due to unknown reasons. Clinical efficacy reasons included lack of improvement (34/104, 32.7%), targeted treatment (30/104, 28.8%), subtherapeutic drug levels (14/104, 13.5%) and other (26/104, 25%). Toxicity reasons included hepatotoxicity, nephrotoxicity, drug interactions, neurotoxicity and other in 24 (43.6%), 12 (21.8%), 12 (21.8%), 4 (7.4%) and 3 (5.5%) cases respectively. All‐cause 12‐week mortality was 31% (19/61), higher in patients whose antifungal treatment (logrank 0.04) or appropriate antifungal treatment (logrank 0.01) was started >7 days post‐IMI diagnosis. All‐cause 1‐year mortality was higher in patients with ≥2 changes of treatment during the first 6 weeks post‐IMI diagnosis (logrank 0.008) with an OR: 4.00 (p = .04).

Conclusions

Patients with IMI require long treatment courses with multiple changes for variable reasons and potential effects on clinical outcomes, demonstrating the need more effective and safer treatment options. Early initiation of appropriate antifungal treatment is associated with improved outcomes.

Clinical Considerations of Isavuconazole Administration in High-Risk Hematological Patients: A Single-Center 5-Year Experience

Background

There are limited real-life data on isavuconazole prophylaxis and treatment of invasive mold infections (IMI) in hematological patients and allogeneic hematopoietic cell transplant (HCT) recipients.

Objectives

Primary objective was to describe the indications of real-life isavuconazole administration at a university hospital. Secondary objectives included the description of liver function tests and QTc interval between baseline and end of treatment (EOT), clinical outcomes and breakthrough IMI by the EOT.

Patients/Methods

This was a 5-year single-center retrospective study of all adult patients with acute myeloid leukemia and/or allogeneic HCT recipients who received isavuconazole as prophylaxis and/or treatment between June 1, 2016, and July 31, 2020.

Results

Among 30 identified patients, the indications for isavuconazole administration were adverse events associated with prior antifungal treatment (N: 18, 60%: hepatotoxicity, renal insufficiency, long QTc interval, neurotoxicity, and potential drug–drug interactions in 6, 4, 3, 1 and 4 patients, respectively), clinical efficacy (N: 5, 16.6%), and other reasons (N: 10, 33.3%; 5/10 patients treated with isavuconazole to facilitate hospital discharge with orally administered appropriate treatment). Alanine aminotransferase significantly decreased from baseline (mean: 129 IU/L, range: 73, 202) to a mean of 48 IU/L (range: 20, 80) by day 14 (P-value: 0.02), 23.5 IU/L (range: 20, 27) by day 28 (P-value: 0.03) and 16.5 IU/L (range: 16, 17) by day 42 (P-value: 0.009). The QTc interval decreased from baseline (mean: 456.8 ms, range: 390, 533) to EOT (mean: 433.8 ms, range: 400, 472; P-value: 0.03). The mean isavuconazole plasma concentration was 2.9 mg/L (range: 0.9, 6.7). There was no breakthrough IMI observed.

Conclusion

Isavuconazole is a safe and reliable antifungal agent in complex hematological patients, with relatively low hepatotoxicity and QTc interval shortening properties.

Predictors of breakthrough clinically significant cytomegalovirus infection during letermovir prophylaxis in high-risk hematopoietic cell transplant recipients

Letermovir prophylaxis in allogeneic hematopoietic cell transplant recipients significantly reduces the incidence of clinically significant cytomegalovirus infection. However, breakthrough infections still occur despite adequate prophylaxis. In the present retrospective cohort study, we identified clinically relevant predictive factors for clinically significant CMV breakthrough infection during letermovir prophylaxis. Low‐grade CMV replication (21–149 IU/ml), both at the time of letermovir initiation or during prophylaxis, was a significant risk factor for breakthrough clinically significant CMV infection. In addition, development of acute gastrointestinal graft‐versus‐host disease was significantly associated with breakthrough infection. Altogether these findings could call clinicians' attention to closer CMV monitoring and allow for prompt preemptive treatment initiation.

Unmasking viral sequences by metagenomic next-generation sequencing in adult human blood samples during steroid-refractory/dependent graft-versus-host disease

BACKGROUND

Viral infections are common complications following allogeneic hematopoietic stem cell transplantation (allo-HSCT). Allo-HSCT recipients with steroid-refractory/dependent graft-versus-host disease (GvHD) are highly immunosuppressed and are more vulnerable to infections with weakly pathogenic or commensal viruses. Here, twenty-five adult allo-HSCT recipients from 2016 to 2019 with acute or chronic steroid-refractory/dependent GvHD were enrolled in a prospective cohort at Geneva University Hospitals. We performed metagenomics next-generation sequencing (mNGS) analysis using a validated pipeline and de novo analysis on pooled routine plasma samples collected throughout the period of intensive steroid treatment or second-line GvHD therapy to identify weakly pathogenic, commensal, and unexpected viruses.

RESULTS

Median duration of intensive immunosuppression was 5.1 months (IQR 5.5). GvHD-related mortality rate was 36%. mNGS analysis detected viral nucleotide sequences in 24/25 patients. Sequences of ≥ 3 distinct viruses were detected in 16/25 patients; Anelloviridae (24/25) and human pegivirus-1 (9/25) were the most prevalent. In 7 patients with fatal outcomes, viral sequences not assessed by routine investigations were identified with mNGS and confirmed by RT-PCR. These cases included Usutu virus (1), rubella virus (1 vaccine strain and 1 wild-type), novel human astrovirus (HAstV) MLB2 (1), classic HAstV (1), human polyomavirus 6 and 7 (2), cutavirus (1), and bufavirus (1).

CONCLUSIONS

Clinically unrecognized viral infections were identified in 28% of highly immunocompromised allo-HSCT recipients with steroid-refractory/dependent GvHD in consecutive samples. These identified viruses have all been previously described in humans, but have poorly understood clinical significance. Rubella virus identification raises the possibility of re-emergence from past infections or vaccinations, or re-infection. Video abstract.

Clinical considerations on posaconazole administration and therapeutic drug monitoring in allogeneic hematopoietic cell transplant recipients

There is a paucity of data on posaconazole (PCZ) dosing and therapeutic-drug-monitoring (TDM) in allogeneic hematopoietic cell transplant recipients (allogeneic-HCTr). This was a 3-year retrospective multicenter study (January 1, 2016 to December 31, 2018) in adult allogeneic-HCTr who received PCZ (intravenously, IV and/or as delayed-release tablet, DRT) as prophylaxis or treatment for ≥7 consecutive days (D) with at least 1-PCZ-level available using data of the Swiss Transplant Cohort Study. The primary objective was to describe the distribution of PCZ-level and identify predictors of therapeutic PCZ-level and associations between PCZ-dosing and PCZ-level. A total of 288 patients were included: 194 (67.4%) and 94 (32.6%) received PCZ as prophylaxis and treatment, respectively, for a median of 90 days (interquartile range, IQR: 42-188.5). There were 1944 PCZ-level measurements performed, with a median PCZ level of 1.3 mg/L (IQR: 0.8-1.96). PCZ-level was <0.7 mg/L in 383/1944 (19.7%) and <1.0 mg/L in 656/1944 (33.7%) samples. PCZ-level was <0.7 mg/L in 260/1317 (19.7%) and <1.0 mg/L in 197/627 (31.4%) in patients who received PCZ-prophylaxis versus treatment, respectively. There were no significant differences in liver function tests between baseline and end-of-treatment. There were nine (3.1%) breakthrough invasive fungal infections (bIFI), with no difference in PCZ levels between patients with or without bIFI. Despite a very intensive PCZ-TDM, PCZ-levels remain below target levels in up to one-third of allogeneic-HCTr. Considering the low incidence of bIFI observed among patients with PCZ levels in the targeted range, our data challenge the clinical utility of routine universal PCZ-TDM.

Evaluation of Disease Risk Comorbidity Index after Allogeneic Stem Cell Transplantation in a Cohort with Patients Undergoing Transplantation with In Vitro Partially T Cell Depleted Grafts

Outcomes of hematopoietic stem cell transplantation (HSCT) are influenced by comorbidities, disease type, and status at transplantation. Several prognostic scores can be used, such as the disease risk index (DRI) or the hematopoietic cell transplantation-specific comorbidity index (HCT-CI). Recently, a new prognostic tool, the disease risk comorbidity index (DRCI), combining the DRI and the HCT-CI, was published. The DRCI determines 6 patient groups (very low risk [VLR], low risk [LR], intermediate risk 1 [IR-1], intermediate risk 2 [IR-2], high risk [HiR], and very high risk [VHR]) with a significant predictive value for overall survival (OS), disease-free survival (DFS), relapse incidence (RI), and graft-versus-host disease-free/relapse-free survival (GRFS). However, the DRCI has not been evaluated for patients allografted with partially in vitro T cell depleted (pTDEP) grafts. In our center, we offer pTDEP to reduce graft-versus-host disease for patients in complete remission at transplant time. In this retrospective study, we investigated the DRCI in 404 adult patients (including 37.6% pTDEP) undergoing a first HSCT for hematological malignancies from 2008 to 2018. Because of the small number of patients in LR, VLR and LR were combined for analysis. In the entire cohort, 2-year OS was 84.4% (95% CI, 71.6% to 97.2%) for LR, 61.6% (54.8% to 68.4%) for IR-1, 45.7% (33.3% to 58.1%) for IR-2, 31% (19.4% to 42.6%) for HiR, and 30.9% (14.5% to 47.3%) for VHR (P < .001). In addition, the DRCI was predictive of DFS, RI, and GRFS but not of nonrelapsed mortality and graft-versus-host disease. Our study confirms similar results with the original publication but gives less accurate prognosis information than the DRI and HCT-CI when used separately. In conclusion, the DRCI does not seem to offer more relevant information than the DRI and HCT-CI to help physicians and patients for the HSCT decision.

[Allogeneic hematopoietic stem cell transplant in children and adults with sickle cell disease: Indications and modalities]

Sickle cell disease is associated with severe complications and early mortality in adults. In children, hematopoietic stem cell transplant from HLA-identical sibling can stop the progression of the disease and leads to more than 95% long-term free survival without sickle cell disease. The aim of this workshop was to define indications and modalities of allogeneic hematopoietic stem cell transplant in children and adults with sickle cell disease. Patient and sibling HLA typing should be proposed, early in the course of the disease, when intensification therapies are required. Indications of transplant from HLA-identical sibling in children and adults are, cerebral vasculopathy, occurrence of vaso-occlusive events despite hydroxycarbamide, renal and hepatic diseases related to SCD, chronic anemia<7g/dL despite hydroxycarbamide, need to maintain transfusion programs longer than six months, and major transfusion difficulties related to red blood cell alloimmunization. In children with an HLA-identical sibling donor, we recommend a myeloablative conditioning regimen associating high dose busulfan, cyclophosphamide and ATG, considering the excellent results of this approach In patients over 15 years of age, we recommend the NIH approach consisting of a reduced intensity conditioning regimen by alemtuzumab, and 3Gy total body irradiation, followed by peripheral hematopoietic stem cells and post-transplant immunosuppression by sirolimus In the absence of HLA-identical sibling donor, there is no definitive data for preferring transplant from unrelated versus haplo-identical donors but we recommend to evaluate these approaches in prospective trials.

Optimal Treatment Duration of Pseudomonas aeruginosa Infections in Allogeneic Hematopoietic Cell Transplant Recipients

In a large, multicenter, contemporary, 8-year, cohort study, one third of allogeneic-hematopoietic cell transplant (HCT) recipients with Pseudomonas aeruginosa (PSA) infection developed a recurrent infection within 3 months. Antibiotic treatment duration of ≥14 days was the only significantly associated variable with reduced recurrence rates of PSA infections in allogeneic-HCT recipients.

Compartmentalization of a Multidrug-Resistant Cytomegalovirus UL54 Mutant in a Stem Cell Transplant Recipient with Encephalitis

We report a case of cytomegalovirus encephalitis in a hematopoietic stem cell transplant recipient. A previously uncharacterized V787E mutation in UL54 was identified in cerebrospinal fluid but not plasma specimens. For the V787E recombinant virus, the half maximal effective concentrations for ganciclovir, foscarnet, and cidofovir were 8.6-, 3.4- and 2.9-fold higher than for wild-type virus, and the replicative capacity was lower. The introduction of a bulkier and negatively charged glutamate residue at position 787 could destabilize the finger domain of UL54 DNA polymerase. Viral genotyping of cerebrospinal fluid is warranted in subjects with cytomegalovirus encephalitis, owing to the low penetration of antivirals in this compartment.

Torque Teno Virus as a Potential Biomarker for Complications and Survival After Allogeneic Hematopoietic Stem Cell Transplantation

Impaired immune reconstitution after allogeneic hematopoietic stem cell transplantation (HSCT) contributes to increased risk of cancer relapse and infection resulting in significant morbidity and mortality. Unfortunately, effective strategies to functionally assess the quality of immune reconstitution are still missing. Quantification of in vivo replication of the ubiquitous, non-pathogenic virus Torque Teno Virus (TTV) has been reported in small series as a test to functionally evaluate the quality of post-transplant immune reconstitution. In the present study, we analyzed by quantitative PCR TTV titers in plasma samples from a large cohort of 168 allogeneic HSCT recipients. Our analysis confirms that TTV titers peaked at 100 days post-transplant, followed by progressive normalization thereafter. Negative correlation of TTV titers with T cell absolute numbers during the first year post-transplant points to the restoration of an active anti-TTV immunity. Univariable and multivariable linear regression analysis demonstrated that donor CMV positive serostatus, donor type and immune suppression resulting from GVHD treatment affected the restoration of anti-TTV immunity. Importantly, higher TTV titers at 100 days after transplantation were associated with worse overall survival and higher risk of acute GVHD and infections. Our results provide new insights into the factors affecting the dynamics of TTV replication and indicate that TTV is a potentially useful biomarker to assess immune reconstitution and to predict complications and outcomes of allogeneic HSCT.

Microbiologically documented infections after adult allogeneic hematopoietic cell transplantation: A 5-year analysis within the Swiss Transplant Cohort study

BACKGROUND

Infections are an important complication after allogeneic hematopoietic cell transplantation (allo-HCT). The present study aimed at determining the landscape of infections occurring in a large cohort of allo-HCT patients, as well as associated risk factors for infections and for one-year non-relapse mortality.

METHODS

This is a retrospective cohort study using STCS and EBMT databases to assess the one-year incidence rate of infection, as well as risk factors for infections and for one-year non-relapse mortality among adult allo-HCT patients transplanted between 2010 and 2014 in Switzerland. Univariable and multivariable quasi-Poisson and multivariable Cox regression models were used.

RESULTS

Of 553 patients included, 486 had an infection with a global incidence rate of 3.66 infections per patient-year. Among a total of 1534 infections analyzed, viral infections were predominant (n = 1138, 74.2%), followed by bacterial (n = 343, 22.4%) and fungal (n = 53, 3.5%) infections. At one year, the cumulative incidence of relapse and non-relapse mortality was 26% and 16%, respectively. 195 (35.3%) of patients had at least one episode of severe graft-versus-host-disease (GvHD). A center effect was observed, and underlying disease, donor type, cytomegalovirus serological constellation, and GvHD were also associated with the incidence rate of infections. There was an increased risk for one-year non-relapse mortality associated with all pathogens, specifically within two months of infection, and this remained true beyond 2 months of a fungal infection.

CONCLUSION

Despite advances to limit infections in this population, they still occur in most allo-HCT patients with a major impact on survival at 1 year.

[Management of CAR-T cell-related encephalopathy syndrome in adult and pediatric patients: Recommendations of the French Society of Bone Marrow transplantation and cellular Therapy (SFGM-TC)]

CAR-T cell-related encephalopathy syndrome (CRES) reflects the potential neurotoxicity of this therapeutic approach and must be considered in the presence of any neurological symptom after the infusion of the CAR-T. This is the second most common adverse event under this therapy and its incidence varies between 12 and 55%. The median time of the onset of the first neurologic symptoms is 4days after CAR-T infusion. The duration of CRES symptoms is generally between 2 and 4days, but late CRES may occur. Monitoring and diagnosis of CERS includes clinical exam, magnetic resonance imaging and electroencephalography. In addition to symptomatic treatments, corticosteroids represent the cornerstone of the high-grade CERS treatment. Drugs targeting IL-6 should be restricted to severe forms, especially those associated with cytokine release syndrome. The purpose of this workshop is to provide practical help in dealing with this complication.

Dynamics of Expression of Programmed Cell Death Protein-1 (PD-1) on T Cells After Allogeneic Hematopoietic Stem Cell Transplantation

Immune exhaustion contributes to treatment failure after allogeneic hematopoietic stem cell transplantation (HSCT) for hematological malignancies. Immune checkpoint blockade, including programmed cell death protein-1 (PD-1) blockade, is a promising strategy to improve the antitumor effect of allogeneic HSCT with high rates of response reported in patients treated for disease relapse. However, severe and sometimes fatal Graft- vs.-Host-Disease (GvHD) has been reported as a complication. Little is known about the dynamics of PD-1 expression on immune effector cells after allogeneic HSCT. In the present study, we analyzed PD-1 expression on T cell subpopulations isolated from 105 allogeneic HSCT recipients. Our analysis revealed a significant increase in proportions of PD-1-expressing CD4 and CD8 T cells early after allogeneic HSCT followed by a progressive normalization of PD-1 expression at CD8 but not CD4 T cell surface. Analysis of co-expression of two other exhaustion markers, 2B4 and CD160, revealed a preferential expansion of PD-1-single positive cells. Moreover, the analysis of granzyme B and perforin expression in PD-1+ and PD-1- CD8 T cells from HSCT recipients did not reveal any impairment in cytotoxic molecules production by PD-1-expressing CD8 T cells. Analyzing the association between clinical factors and the expression of PD-1 on T cells, we identified the use of in vivo and/or ex vivo T-cell depletion as the factor most strongly associated with elevated PD-1 levels on T cells. Our results extend our knowledge of the regulation of PD-1 expression at T cell surface after allogeneic HSCT, a crucial information for the optimization of post-transplantation PD-1 blocking therapies.

[Management of cytokine release syndrome in adult and pediatric patients undergoing CAR-T cell therapy for hematological malignancies: Recommendation of the French Society of Bone Marrow and cellular Therapy (SFGM-TC)]

The cytokine release syndrome (CRS) is the most common complication after adoptive immunotherapies such as chimeric antigen receptor T cells (CAR-T). The incidence varies from 30 to 100% depending on the CAR-T construct, cell doses and the underlying disease. Severe cases may involve 10 to 30% of patients. The triggering event is the activation of the CAR-T, after meeting with their target. The T cell activation leads to the release of effector cytokines, such as IFNγ, TNFα and IL2, that are responsible for the activating of monocyte/macrophage system, resulting in the production of pro-inflammatory cytokines, (including IL6, IFN-γ, IL10, MCP1) and associated with a significant elevation of CRP and ferritin. The CRS usually appears between 1 and 14days after the infusion of the cells and can last from 1 to 10days. Rare fatal cases have been reported in the literature. The first symptom is often a fever, sometimes very high, which must alert and reinforce the surveillance. In moderate forms, one can find fatigue, headache, rash, arthralgia and myalgia. T cell-related encephalopathy (CRES) syndrome may occur concomitantly. In case of aggravation, a vasoplegic shock associating capillary leakage and respiratory distress can occur. Close clinical monitoring is essential right from the injection to quickly detect the first symptoms. The treatment of severe forms, in addition to symptomatic management involves monoclonal antibodies targeting the IL6 or IL6 receptor, and sometimes steroids. Close cooperation with intensive care units is essential since 20 to 50% of patients require intensive care unit transfer.

Human pegivirus persistence in human blood virome after allogeneic haematopoietic stem-cell transplantation

OBJECTIVES

Because commensal viruses are defined by the immunologic tolerance afforded to them, any immunomodulation, such as is received during haematopoietic stem-cell transplantation, may shift the demarcation between innocuous viral resident and disease-causing pathogen.

METHODS

We analysed by deep-sequencing the plasma virome of 40 allogeneic haematopoietic stem-cell transplantation patients 1 month after transplantation. Because human pegivirus (HPgV) was highly prevalent, we performed a 1-year screening of 122 plasma samples by specific real-time reverse transcription PCR assay. We used the log-rank test and the Gray test to assess association with outcomes, and the Mann-Whitney test and multivariable linear regression model to assess association with T-cell reconstitution.

RESULTS

Polyomaviruses (PyV) (20/40 patients), anelloviruses (16/40), pegiviruses (14/40) and herpesviruses (14/40) were most frequently identified, including ten cytomegalovirus; three Epstein-Barr virus; two herpes simplex virus type 1; one human herpesvirus 6b and one human herpesvirus 7; 18 Merkel cell-PyV; two BK-PyV; three PyV-6; and one JC-PyV. Papillomavirus and adenovirus were identified in 11 and two patients, respectively. The HPgV specific real-time reverse transcription PCR screening identified 51 of 122 positive samples, high virus loads and persistent infections up to 1 year after transplantation. Comparison between patients with or without HPgV infection at time of transplantation did not reveal a significant difference in infections, engraftment, survival, graft vs. host disease, relapse or immune reconstitution.

CONCLUSIONS

The blood virome after allogeneic haematopoietic stem-cell transplantation includes several DNA viruses, notably herpesviruses and PyV. Among RNA viruses, HPgV is highly prevalent and persists for several months, and it thus may deserve special attention in further research on immune reconstitution.

Burden of severe RSV disease among immunocompromised children and adults: a 10 year retrospective study

Background

Respiratory syncytial virus (RSV) is associated with significant mortality rates amongst hematopoietic stem cell transplant (HSCT) recipients, with less known about other immunocompromised patients.

Methods

Ten-year retrospective cohort study of immunocompromised patients presenting with RSV disease documented at University Hospitals of Lausanne and Geneva. Severe RSV-related outcomes referred to RSV documented respiratory conditions requiring hospital admission, presenting as lower respiratory tract infection (LRTI) or pneumonia. We used multivariable logistic regression to assess clinical and laboratory correlates of severe RSV disease.

Results

From 239 RSV-positive immunocompromised in and out-patients 175 were adults and 64 children of whom 111 (47.8%) presented with LRTI, which resulted in a 38% (89/239) admission rate to hospital. While immunocompromised children were more likely to be admitted to hospital compared to adults (75% vs 62.9%, p = 0.090), inpatients admitted to the intensive care unit (17/19) or those who died (11/11) were mainly adults. From multivariable analyses, adults with solid tumors (OR 5.2; 95% CI: 1.4–20.9 P = 0.015) or those requiring chronic immunosuppressive treatments mainly for rheumatologic conditions (OR 4.1; 95% CI: 1.1–16.0; P = 0.034) were significantly more likely to be admitted to hospital compared to hematopoietic stem cell (HSCT) recipients. Bacterial co-infection was significantly and consistently associated with viral LRTI and pneumonia.

Conclusions

From our findings, RSV-related disease results in a significant burden among adults requiring chronic immunosuppressive treatments for rheumatological conditions and those with solid tumors. As such, systematic screening for respiratory viruses, should be extended to other immunocompromised populations than HSCT recipients.

Electronic supplementary material

The online version of this article (10.1186/s12879-018-3002-3) contains supplementary material, which is available to authorized users.

Haematopoietic cell transplantation in Switzerland, changes and results over 20 years: a report from the Swiss Blood Stem Cell Transplantation Working Group for Blood and Marrow Transplantation registry 1997-2016

In 1997, the Swiss Blood Stem Cell Transplantation Group (SBST) initiated a mandatory national registry for all haematopoietic stem cell transplants (HCTs) in Switzerland. As of 2016, after 20 years, information was available for 7899 patients who had received an HCT (2781 allogeneic [35%] and 5118 autologous [65%]). As some patients had more than one transplant the total number of transplants was 3067 allogeneic and 6448 autologous. We compared patient characteristics and outcome of the first decade (1997-2006) and second decade (2007-2016) of the registry. There were numerous changes over time. For allogeneic HCT, transplant rates, and therefore use of HCT technology, increased from 14 to 21.8 HCTs per 1 million inhabitants per year from the first to the second decade. Likewise autologous HCTs increased from 24.8 to 37.2 annually corrected for population growth. Allogeneic transplant recipients were older (38.4 vs 48.3 years) and more frequently had unrelated donors in the second decade. Similarly, age increased for recipients of autologous HCT (50.8 vs 56.4 years). Analysis of outcome showed that the probabilities of overall and progression-free survival were stable over time, in spite of the treatment of older and higher risk patients. In multivariate analysis, nonrelapse mortality decreased in recipients of allogeneic HCT (relative risk 0.68, 95% confidence interval 0.52-0.87) over the two decades. Improvement in adjusted nonrelapse mortality compensated for the fact that higher risk patients were treated in more recent years, resulting in similar overall survival. Five-year survival probabilities were 56% (53-59%) in the first and 54% (51-57%) in the second decade for allogeneic HCT, and 59% (57-61%) in the first and 61% (59-63%) in the second decade for autologous HCT. Detailed analyses of changes over time are presented. This study included all HCTs performed in Switzerland during the period of observation and the data are useful for quality assurance programmes, healthcare cost estimation and healthcare planning. Between 50 and 60% of patients were long-term survivors after both types of HCT, indicating growing populations of surviving patients requiring long-term care and observation.

Immunological Basis of Bone Marrow Failure after Allogeneic Hematopoietic Stem Cell Transplantation

Bone marrow failure (BMF) syndromes are severe complications of allogeneic hematopoietic stem cell transplantation (allo-HSCT). In this paper, we distinguish two different entities, the graft failure (GF) and the poor graft function (PGF), and we review the current understanding of the interactions between the immune and hematopoietic compartments in these conditions. We first discuss how GF occurs as the result of classical alloreactive immune responses mediated by residual host cellular and humoral immunity persisting after conditioning and prevented by host and donor regulatory T cells. We next summarize the current knowledge about the contribution of inflammatory mediators to the development of PGF. In situations of chronic inflammation complicating allo-HSCT, such as graft-versus-host disease or infections, PGF seems to be essentially the result of a sustained impairment of hematopoietic stem cells (HSC) self-renewal and proliferation caused by inflammatory mediators, such as interferon-γ (IFN-γ) and tumor necrosis factor-α, and of induction of apoptosis through the Fas/Fas ligand pathway. Interestingly, the production of inflammatory molecules leads to a non-MHC restricted, bystander inhibition of hematopoiesis, therefore, representing a promising target for immunological interventions. Finally, we discuss immune-mediated impairment of bone marrow microenvironment as a potential mechanism hampering hematopoietic recovery. Better understanding of immunological mechanisms responsible for BMF syndromes after allo-HSCT may lead to the development of more efficient immunotherapeutic interventions.

[Non-infectious lung diseases after hematopoietic stem cell transplantation]

Non-infectious pulmonary complications following hematopoietic stem cell transplantation are entities occuring early or late, depending on whether they occur before or after 100 days post-transplantation. They have firstly to be differentiated from infectious complications, which is not always easy, as their clinical and radiological aspects can mimic a viral or bacterial pneumonia. Corticosteroids are the most given treatment but a significant subset of patients have a fatal outcome. This article will review the clinical, radiological, functionnal features and the therapeutic options of six entities (engraftment syndrome, diffuse alveolar hemorrage, idiopathic pneumonia syndrome, organizing pneumonia, bronchiolitis obliterans, post-transplantation lympho-proliferative disease).

NK Cell Functional Impairment after Allogeneic Hematopoietic Stem Cell Transplantation Is Associated with Reduced Levels of T-bet and Eomesodermin

NK cells play a major role in protection against tumor recurrence and infection after allogeneic hematopoietic stem cell transplantation (HSCT). It has been shown that NK cell function after HSCT is impaired, but underlying molecular mechanisms are not well-known. In this report we show that the level of T-bet and Eomesodermin (Eomes), two T-box transcription factors regulating lymphocyte effector functions, is strongly reduced in NK cells from HSCT recipients compared with healthy control subjects. Reduction of T-bet and Eomes expression appeared early and persisted for years after HSCT, affecting all peripheral blood NK cells independently of their differentiation status. Reduced T-bet levels in NK cells from allogeneic HSCT recipients significantly correlated with reduced perforin expression. Acute, but not chronic, graft-versus-host disease, as well as CMV reactivation, was associated with further downregulation of T-bet expression in NK cells. Lower levels of T-bet expression in NK cells were associated with less favorable outcome after HSCT as a result of increased nonrelapse mortality. Collectively, our results provide a possible molecular explanation for the previously reported functional exhaustion of NK cells after allogeneic HSCT and suggest an impact of the NK transcriptional machinery status on HSCT outcome.