Consensus criteria for diagnosis, staging, and treatment response assessment of T-cell prolymphocytic leukemia.

T-cell prolymphocytic leukemia (T-PLL) is a rare, mature T-cell neoplasm with a heterogeneous clinical course. With the advent of novel treatment options that will potentially change the management of patients with T-PLL, it has become necessary to produce consensus guidelines for the design and conduct of clinical trials. The T-PLL International Study group (TPLL-ISG) set out to define standardized criteria for diagnosis, treatment indication, and evaluation of response. These criteria will facilitate comparison of results from clinical trials in T-PLL, and will thus support clinical decision making, as well as the approval of new therapeutics by healthcare authorities.

The assessment of platelet function by thromboelastometry as a point-of-care test to guide Intercept-treated platelet support in hemato-oncological patients and hematopoietic stem cell transplantation recipients.

BACKGROUND: Pathogen inactivation (PI) techniques for platelet concentrates (PCs) are one of the latest innovations to improve blood safety and reduce the risk of transfusion-transmitted infections (TTIs). An impaired function and in vivo recovery of platelets as well as an increased PC demand are concerns regarding these techniques. The intent of this study was to evaluate the hemostatic effect of PCs treated with the Intercept™ System by thromboelastometry (TEM) and to assess the clinical validity of its results in comparison to post-transfusion increase (PTI) and corrected count increment (CCI). STUDY-DESIGN AND METHODS: This prospective-observational study included 47 patients (m:f = 25:22; median age: 54 years [21-70]) of our Bone Marrow Transplantation unit with hemato-oncological malignancies transfused with Intercept™-treated PCs. Serial TEM measurements were performed just before and 1 hour after PC transfusion and were analyzed for their correlation with PTI and CCI as well as for clinical variables. RESULTS: The majority of our patients had received a hematopoietic stem cell transplantation (HSCT) (n = 41; 87%). In median 9 (1-50) PCs were transfused. Serial TEM, PTI, and CCI measurements were available for 150 transfusion episodes. The median platelet dose transfused was 2.65 × 1011 /unit (1.8-6). The median CCI was 9.250 (0-28.000). We observed a significant improvement in TEM parameters (p < 0.05) after transfusion of PI PCs, which did not mandatory correlate with the 1-hour PTI and CCI. CONCLUSION: Serial TEM measurements indicate the hemostatic effect of Intercept™-treated PCs. The 1-hour PTI and CCI may not appropriately reflect the in vivo function of platelets after PI PC transfusion.

First-in-human response of BCL-2 inhibitor venetoclax in T-cell prolymphocytic leukemia.

T-cell prolymphocytic leukemia (T-PLL) is a rare and aggressive T-lymphoid malignancy usually refractory to current treatment strategies and associated with short overall survival. By applying next-generation functional testing of primary patient-derived lymphoma cells using a library of 106 US Food and Drug Administration (FDA)-approved anticancer drugs or compounds currently in clinical development, we set out to identify novel effective treatments for T-PLL patients. We found that the B-cell lymphoma 2 (BCL-2) inhibitor venetoclax (ABT-199) demonstrated the strongest T-PLL-specific response when comparing individual ex vivo drug response in 86 patients with refractory hematologic malignancies. Mechanistically, responses to venetoclax correlated with protein expression of BCL-2 but not with expression of the BCL-2 family members myeloid cell leukemia 1 (MCL-1) and BCL-XL in lymphoma cells. BCL-2 expression was inversely correlated with the expression of MCL-1. Based on the ex vivo responses, venetoclax treatment was commenced in 2 late-stage refractory T-PLL patients resulting in clinical responses. Our findings demonstrate first evidence of single-agent activity of venetoclax both ex vivo and in humans, offering a novel agent in T-PLL.

Torquetenovirus Dynamics and Immune Marker Properties in Patients Following Allogeneic Hematopoietic Stem Cell Transplantation: A Prospective Longitudinal Study.

Torquetenovirus (TTV) has been proposed as a marker of immune function in patients receiving immunosuppression after solid organ transplantation. This study aimed to define TTV plasma dynamics and investigate clinical associations in patients following allogeneic hematopoietic stem cell transplantation (HSCT). This was a single-center prospective longitudinal study involving 50 consecutive patients treated with HSCT between March 2015 and April 2016. TTV plasma DNA levels were measured with quantitative PCR at 12 consecutive time points during the first year after HSCT. Forty of the 50 patients (80%) had detectable TTV viremia before HSCT (median level, 5.37 log10 copies/mL; interquartile range [IQR], 3.51-6.44 log10 copies/mL). All patients subsequently developed TTV viremia during the follow-up period. Plasma viral loads evolved dynamically over time, with a peak of 8.32 log10 copies/mL (IQR, 7.33-9.35 log10 copies/mL) occurring at 79 days (IQR, 50-117 days) following HSCT and a stable plateau toward the end of the follow-up period. The type of malignancy, the use of antithymocyte globulin during conditioning, and the occurrence of acute graft-versus-host disease requiring systemic therapy had temporary effects on TTV dynamics. TTV levels showed a significant correlation with absolute lymphocyte counts following engraftment (rs = -.27; P < .01) and with cytomegalovirus (CMV; rs=.39; P < .01) and Epstein-Barr virus (EBV; rs=.45; P = .02) viral loads during phases of viremia. Immune-related clinical events were not predicted by TTV levels. TTV viremia occurred universally and was sustained throughout the first year after HSCT. Several variables and events before and after HSCT were correlated with TTV levels and hint toward immune marker properties of TTV, but their complex interactions might perturb the capability of TTV to predict immune-related complications in this population.

Extracorporeal photopheresis as second-line therapy for patients with acute graft-versus-host disease: does the number of cells treated matter?

BACKGROUND: Extracorporeal photopheresis (ECP) has demonstrated efficacy as second-line treatment for steroid-refractory (SR) acute graft-versus-host disease (aGVHD). The aim of our study was to analyze whether the amount of ECP-treated cells in patients with SR, aGVHD has an impact on response at 1 month. STUDY DESIGN AND METHODS: Data on white blood cells, lymphocytes, monocytes, mononuclear cells, and neutrophils, including absolute counts and counts per kilogram of body weight in ECP products from patients with aGVHD, were collected. For each cell population, the median dose per single ECP and the cumulative doses collected during the first week and the first month of treatment were compared with the response to ECP. RESULTS: In total, 99 patients underwent 1215 ECP procedures. Overall response was defined as a complete response if all signs of aGVHD resolved or a partial response if greater than 50% resolution was reached without other, additional immunosuppression. An overall response was obtained by 75% of patients, including 53% complete responses. Univariate analysis showed a correlation of lymphocytes and mononuclear cells/kg body weight for a single procedure and overall response. In logistic regression analysis, no tested variable had an influence on response. In receiver operating characteristic curve analysis, cutoffs of 8.4 × 106 /kg body weight lymphocytes and 13.9 × 106 /kg body weight mononuclear cells were associated with an overall response to ECP at 1 month with 75% sensitivity. CONCLUSION: Our results in patients with steroid-refractory aGVHD confirm that response rates to ECP are high and that certain cutoff values for lymphocytes and mononuclear cells/kg body weight in each individual procedure can predict an overall response to ECP at 1 month.

Influence of body mass index on survival in indolent and mantle cell lymphomas: analysis of the StiL NHL1 trial.

Obesity is a well-known risk factor for the development of cancer, but its influence on the course of disease is still controversial. We investigated the influence of body mass index (BMI) on overall survival (OS) in 502 patients with indolent non-Hodgkin's lymphoma or mantle cell lymphoma in a subgroup analysis of the StiL (Study Group Indolent Lymphomas) NHL1 trial. We defined a cut-off of 22.55 kg/m2 by ROC calculation and Youden Index analysis and stratified patients into "low BMI" and "high BMI". Five-year OS was significantly longer in the high BMI group (82.2%) when compared to that of the low BMI group (66.2%) (HR 0.597; 95%CI 0.370-0.963; p = 0.034). BMI was also an independent prognostic factor for OS in multivariate analysis (HR 0.541; 95%CI 0.332-0.883; p = 0.014). Of note, patients had a significantly lower BMI in the presence than patients in the absence of B-symptoms (p = 0.025). BMI significantly impacts on OS in indolent non-Hodgkin's lymphoma and mantle cell lymphoma, which may be influenced by the effect of B-symptoms on BMI.

Development of a comprehensive prognostic index for patients with chronic lymphocytic leukemia.

In addition to clinical staging, a number of biomarkers predicting overall survival (OS) have been identified in chronic lymphocytic leukemia (CLL). The multiplicity of markers, limited information on their independent prognostic value, and a lack of understanding of how to interpret discordant markers are major barriers to use in routine clinical practice. We therefore performed an analysis of 23 prognostic markers based on prospectively collected data from 1948 CLL patients participating in phase 3 trials of the German CLL Study Group to develop a comprehensive prognostic index. A multivariable Cox regression model identified 8 independent predictors of OS: sex, age, ECOG status, del(17p), del(11q), IGHV mutation status, serum ß2-microglobulin, and serum thymidine kinase. Using a weighted grading system, a prognostic index was derived that separated 4 risk categories with 5-year OS ranging from 18.7% to 95.2% and having a C-statistic of 0.75. The index stratified OS within all analyzed subgroups, including all Rai/Binet stages. The validity of the index was externally confirmed in a series of 676 newly diagnosed CLL patients from Mayo Clinic. Using this multistep process including external validation, we developed a comprehensive prognostic index with high discriminatory power and prognostic significance on the individual patient level. The studies were registered as follows: CLL1 trial (NCT00262782, http://clinicaltrials.gov), CLL4 trial (ISRCTN 75653261, http://www.controlled-trials.com), and CLL8 trial (NCT00281918, http://clinicaltrials.gov).

A modified scoring of the NCCN-IPI is more accurate in the elderly and is improved by albumin and ß2 -microglobulin.

The International Prognostic Index (IPI) has been used for decades in diffuse large B-cell lymphoma (DLBCL). A retrospective cancer registry analysis in North America showed significantly improved results when an enhanced IPI, the National Comprehensive Cancer Network (NCCN)-IPI was applied. This novel score puts more weight on age and high levels of lactate dehydrogenase (LDH). Nevertheless, it remains unclear if these results can be extrapolated to the general population. This retrospective bi-centre analysis included 499 unselected DLBCL patients who were treated with rituximab and anthracycline-based chemoimmunotherapy between 2004 and 2013. In our cohort, the NCCN-IPI was more accurate in identifying patients at low or high risk, despite older age, and more patients with increased LDH. Nevertheless, a modified scoring of the risk factors was required to more accurately identify elderly patients with a very favourable diagnosis, suggesting an impaired value of the original NCCN-IPI in the elderly. Serum ß2 -microglobulin and albumin were retained as independent prognostic factors for survival in a multivariate analysis. Our data confirm, for the first time, the superior prognostic power of the NCCN-IPI in an unselected, middle-European cohort. We furthermore propose a modified NCCN-IPI for more accurate prognostication in the elderly. Albumin and ß2 -microglobulin levels are likely to add significant information to the NCCN-IPI.

Interactions between comorbidity and treatment of chronic lymphocytic leukemia: results of German Chronic Lymphocytic Leukemia Study Group trials.

This study investigated the impact of comorbidity in 555 patients with chronic lymphocytic leukemia enrolled in two trials of the German Chronic Lymphocytic Leukemia Study Group on first-line treatment with fludarabine plus cyclophosphamide, fludarabine, or chlorambucil. Patients with two or more comorbidities and patients with less than two comorbidities differed in overall survival (71.7 versus 90.2 months; P<0.001) and progression-free survival (21.0 versus 31.5 months; P<0.01). After adjustment for other prognostic factors and treatment, comorbidity maintained its independent prognostic value in a multivariate Cox regression analysis. Chronic lymphocytic leukemia was the major cause of death in patients with two or more comorbidities. Disease control in patients with two or more comorbidities was better with fludarabine plus cyclophosphamide than with fludarabine treatment, but not with fludarabine compared to chlorambucil treatment. These results give insight into interactions between comorbidity and therapy of chronic lymphocytic leukemia and suggest that durable control of the hematologic disease is most critical to improve overall outcome of patients with increased comorbidity. The registration numbers of the trials reported are NCT00276848 and NCT00262795.

Lenalidomide in combination with vorinostat and dexamethasone for the treatment of relapsed/refractory peripheral T cell lymphoma (PTCL): report of a phase I/II trial.

Given the poor outcome of relapsed and refractory peripheral T cell lymphoma (PTCL), we explored a combination of lenalidomide, vorinostat, and dexamethasone to test the feasibility of this therapy in relapsed and refractory PTCL. Eight patients were accrued: two peripheral T cell lymphoma, unspecified; five angioimmunoblastic T cell lymphoma; and one ALK-negative anaplastic large-cell lymphoma. A dose escalation of lenalidomide (days 1-21, q28) was planned using a 3 + 3 design. As two patients treated with 10 mg/day experienced dose-limiting toxicity (thrombocytopenia grade 3, stroke grade 4), the primary end point of our trial was reached; the maximal tolerable dose of lenalidomide was 5 mg/day (level -I). Adverse events grade ≥3 were observed as thrombocytopenia (23 %), leukocytopenia (15 %), anemia (8 %), and neutropenia (8 %). One complete remission (10.3 months), one partial remission (11.3 months), one stable disease (11.9 months), and four progressive disease (overall response rate 25 %) were observed. The median progression-free survival was 2.2 months and the median OS was 6.7 months. In conclusion, the poor results obtained with lenalidomide in combination with vorinostat and dexamethasone provide no arguments that could justify further investigation of this drug combination for the treatment of relapsed PTCL.

Sequential chemoimmunotherapy of fludarabine, mitoxantrone, and cyclophosphamide induction followed by alemtuzumab consolidation is effective in T-cell prolymphocytic leukemia.

BACKGROUND: Scarce systematic trial data have prevented uniform therapeutic guidelines for T-cell prolymphocytic leukemia (T-PLL). A central need in this historically refractory tumor is the controlled evaluation of multiagent chemotherapy and its combination with the currently most active single agent, alemtuzumab. METHODS: This prospective multicenter phase 2 trial assessed response, survival, and toxicity of a novel regimen in previously treated (n = 9) and treatment-naive (n = 16) patients with T-PLL. Induction by fludarabine, mitoxantrone, and cyclophosphamide (FMC), for up to 4 cycles, was followed by alemtuzumab (A) consolidation, up to 12 weeks. RESULTS: Of the 25 patients treated with FMC, 21 subsequently received alemtuzumab. Overall response rate to FMC was 68%, comprising 6 complete remissions (all bone-marrow confirmed) and 11 partial remissions. Alemtuzumab consolidation increased the intent-to-treat overall response rate to 92% (12 complete remissions; 11 partial remissions). Median overall survival after FMC-A was 17.1 months and median progression-free survival was 11.9 months. Progression-free survival tended to be shorter for patients with high-level T-cell leukemia 1 oncoprotein expression. Hematologic toxicities were the most frequent grade 3/4 side effects under FMC-A. Exclusively in the 21 alemtuzumab-consolidated patients, 13 cytomegalovirus reactivations were observed; 9 of these 13 represented a clinically relevant infection. CONCLUSIONS: FMC-A is a safe and efficient protocol in T-PLL, which compares favorably to published data.

Limited clinical relevance of imaging techniques in the follow-up of patients with advanced chronic lymphocytic leukemia: results of a meta-analysis.

The clinical value of imaging is well established for the follow-up of many lymphoid malignancies but not for chronic lymphocytic leukemia (CLL). A meta-analysis was performed with the dataset of 3 German CLL Study Group phase 3 trials (CLL4, CLL5, and CLL8) that included 1372 patients receiving first-line therapy for CLL. Response as well as progression during follow-up was reassessed according to the National Cancer Institute Working Group1996 criteria. A total of 481 events were counted as progressive disease during treatment or follow-up. Of these, 372 progressions (77%) were detected by clinical symptoms or blood counts. Computed tomography (CT) scans or ultrasound were relevant in 44 and 29 cases (9% and 6%), respectively. The decision for relapse treatment was determined by CT scan or ultrasound results in only 2 of 176 patients (1%). CT scan results had an impact on the prognosis of patients in complete remission only after the administration of conventional chemotherapy but not after chemoimmunotherapy. In conclusion, physical examination and blood count remain the methods of choice for staging and clinical follow-up of patients with CLL as recommended by the International Workshop on Chronic Lymphocytic Leukemia 2008 guidelines. These trials are registered at http://www.isrctn.org as ISRCTN 75653261 and ISRCTN 36294212 and at http://www.clinicaltrials.gov as NCT00281918.

Mixed-phenotype acute leukemia: clinical and laboratory features and outcome in 100 patients defined according to the WHO 2008 classification.

The features of 100 mixed-phenotype acute leukemias (MPALs), fulfilling WHO 2008 criteria, are documented. Myeloid and T-lineage features were demonstrated by cytoplasmic myeloperoxidase and CD3; B-lineage features were demonstrated by at least 2 B-lymphoid markers. There were 62 men and 38 women; 68% were adults. Morphology was consistent with acute lymphoblastic leukemia (ALL; 43%), acute myeloid leukemia (AML; 42%), or inconclusive (15%). Immunophenotyping disclosed B + myeloid (59%), T + myeloid (35%), B + T (4%), or trilineage (2%) combinations. Cytogenetics evidenced t(9;22)/(Ph(+)) (20%), 11q23/MLL rearrangements (8%), complex (32%), aberrant (27%), or normal (13%) karyotypes. There was no correlation between age, morphology, immunophenotype, or cytogenetics. Response to treatment and outcome were available for 67 and 70 patients, respectively; 27 received ALL, 34 AML, 5 a combination of ALL + AML therapy, and 1 imatinib. ALL treatment induced a response in 85%, AML therapy in 41%; 3 of 5 patients responded to the combination therapy. Forty (58%) patients died, 33 of resistant disease. Overall median survival was 18 months and 37% of patients are alive at 5 years. Age, Ph(+), and AML therapy were predictors for poor outcome (P < .001; P = .002; P = .003). MPAL is confirmed to be a poor-risk disease. Adults and Ph(+) patients should be considered for transplantation in first remission.

Rituximab serum concentrations during immuno-chemotherapy of follicular lymphoma correlate with patient gender, bone marrow infiltration and clinical response.

BACKGROUND: Treatment of follicular lymphoma with rituximab is currently recommended at a dose of 375 mg/m(2). We aimed to provide a rationale for optimal dosing and scheduling of this anti-CD20 antibody based on pharmacokinetics. DESIGN AND METHODS: Clinical efficacy of immunochemotherapy with rituximab, fludarabine and mitoxantrone followed by 2-monthly rituximab maintenance was evaluated in 29 patients with previously untreated follicular lymphoma in a prospective phase II trial (AGMT-NHL9). Pharmacokinetic analysis was assessed in 17 patients. RESULTS: Induction treatment resulted in high clinical response rates (complete remission 66%; ORR 100%). Significantly higher complete remission rates were observed in female patients (86 vs. 47%; Odds Ratio 6.8, 95% CI: 1.12; 41.82; P=0.05). Rituximab pharmacokinetic analysis showed a high variability ranging over almost 1 order of magnitude at maintenance cycle 1 (area under the curve 1,540-12,025 g/L*days). Median area under the curve was lower in men (81%) and in patients with initial bone marrow infiltration (76%). Higher rituximab serum concentrations before next therapy (C(trough)) were associated with female sex (P=0.04) as well as with absence of initial bone marrow infiltration (P=0.001). C(trough) correlated with remission quality (complete vs. partial remission; P=0.005) and progression-free survival (P=0.03). A decline in rituximab C(trough) below 25,000 ng/mL was observed 9.5 to 62 months before clinical relapse (P=0.008). CONCLUSIONS: The results of this pilot trial suggest that more differentiated dosing schedules based on gender and bone marrow infiltration should be explored for rituximab therapy for lymphoma. This study was registered in ClinicalTrials.gov (Identifier: NCT01560117).

The frequency of differentiated CD3+CD27-CD28- T cells predicts response to CART cell therapy in diffuse large B-cell lymphoma.

Background: Chimeric antigen receptor T (CART) cell therapy targeting the B cell specific differentiation antigen CD19 has shown clinical efficacy in a subset of relapsed/refractory (r/r) diffuse large B cell lymphoma (DLBCL) patients. Despite this heterogeneous response, blood pre-infusion biomarkers predicting responsiveness to CART cell therapy are currently understudied. Methods: Blood cell and serum markers, along with clinical data of DLBCL patients who were scheduled for CART cell therapy were evaluated to search for biomarkers predicting CART cell responsiveness. Findings: Compared to healthy controls (n=24), DLBCL patients (n=33) showed significant lymphopenia, due to low CD3+CD4+ T helper and CD3-CD56+ NK cell counts, while cytotoxic CD3+CD8+ T cell counts were similar. Although lymphopenic, DLBCL patients had significantly more activated HLA-DR+ (P=0.005) blood T cells and a higher frequency of differentiated CD3+CD27-CD28- (28.7 ± 19.0% versus 6.6 ± 5.8%; P<0.001) T cells. Twenty-six patients were infused with CART cells (median 81 days after leukapheresis) and were analyzed for the overall response (OR) 3 months later. Univariate and multivariate regression analyses showed that low levels of differentiated CD3+CD27-CD28- T cells (23.3 ± 19.3% versus 35.1 ± 18.0%) were independently associated with OR. This association was even more pronounced when patients were stratified for complete remission (CR versus non-CR: 13.7 ± 11.7% versus 37.7 ± 17.4%, P=0.001). A cut-off value of ≤ 18% of CD3+CD27-CD28- T cells predicted CR at 12 months with high accuracy (P<0.001). In vitro, CD3+CD8+CD27-CD28- compared to CD3+CD8+CD27+CD28+ CART cells displayed similar CD19+ target cell-specific cytotoxicity, but were hypoproliferative and produced less cytotoxic cytokines (IFN-γ and TNF-α). CD3+CD8+ T cells outperformed CD3+CD4+ T cells 3- to 6-fold in terms of their ability to kill CD19+ target cells. Interpretation: Low frequency of differentiated CD3+CD27-CD28- T cells at leukapheresis represents a novel pre-infusion blood biomarker predicting a favorable response to CART cell treatment in r/r DLBCL patients.

Functional Precision Medicine Provides Clinical Benefit in Advanced Aggressive Hematologic Cancers and Identifies Exceptional Responders.

Personalized medicine aims to match the right drug with the right patient by using specific features of the individual patient's tumor. However, current strategies of personalized therapy matching provide treatment opportunities for less than 10% of patients with cancer. A promising method may be drug profiling of patient biopsy specimens with single-cell resolution to directly quantify drug effects. We prospectively tested an image-based single-cell functional precision medicine (scFPM) approach to guide treatments in 143 patients with advanced aggressive hematologic cancers. Fifty-six patients (39%) were treated according to scFPM results. At a median follow-up of 23.9 months, 30 patients (54%) demonstrated a clinical benefit of more than 1.3-fold enhanced progression-free survival compared with their previous therapy. Twelve patients (40% of responders) experienced exceptional responses lasting three times longer than expected for their respective disease. We conclude that therapy matching by scFPM is clinically feasible and effective in advanced aggressive hematologic cancers. SIGNIFICANCE: This is the first precision medicine trial using a functional assay to instruct n-of-one therapies in oncology. It illustrates that for patients lacking standard therapies, high-content assay-based scFPM can have a significant value in clinical therapy guidance based on functional dependencies of each patient's cancer.See related commentary by Letai, p. 290.This article is highlighted in the In This Issue feature, p. 275.

Successful alemtuzumab retreatment in progressive B-cell chronic lymphocytic leukemia: a multicenter survey in 30 patients.

Although retreatment with alemtuzumab in relapsing B-cell chronic lymphocytic leukemia (CLL) may be beneficial, there has thus far been no thorough analysis available on this topic. Data were collected from 30 chemotherapy-pretreated patients with progressive CLL who had received alemtuzumab twice in consecutive, distinct therapy lines. The median dose of alemtuzumab retreatment was 402 mg (range, 43-1,090 mg). Retreatment with alemtuzumab induced an overall response rate of 47%. From the start of alemtuzumab retreatment, median progression-free survival (PFS) and overall survival (OS) were 6.3 and 20.0 months, respectively. Response rates, PFS and OS upon alemtuzumab retreatment were correlated with response to initial alemtuzumab treatment, the time interval between the initial course of alemtuzumab and start of retreatment, and the hemoglobin concentration prior to retreatment. Reported toxicities from 24 cases included infections (50%), febrile reactions upon alemtuzumab administration (38%), exanthema (21%), and grade 4 neutropenia (13%) and thrombocytopenia (17%). We conclude that alemtuzumab retreatment represents an effective and tolerable therapeutic option for selected patients with CLL.

Anti-Apoptotic Molecule BCL2 Is a Therapeutic Target in Steroid-Refractory Graft-Versus-Host Disease.

Graft-versus-host disease (GVHD) is the leading cause of mortality after hematopoietic stem cell transplantation and primarily affects barrier organs such as the skin. One-third of cases are refractory to steroid treatment resulting in poor outcomes and the need for novel therapies. Longitudinal analysis of T-cell transcriptomes in patients before the appearance of GVHD symptoms revealed the upregulation of anti-apoptotic regulator B-cell lymphoma 2 (BCL2) at GVHD initiation. To determine the potential of BCL2 inhibition in active GVHD, we analyzed tissues of 88 patients with acute or chronic GVHD. BCL2 RNA was elevated in multiple organs affected by GVHD and expression correlated with transplant-related mortality and steroid-refractory GVHD. BCL2-expressing lymphocytes were present in skin lesions and peripheral blood of patients with acute and chronic GVHD. Inhibition of BCL2 increased the CD4 to CD8 ratio in allogeneic T cells in vitro and induced apoptosis of T cells from patients with steroid-pretreated chronic GVHD ex vivo. In addition, the higher ratio of regulatory to nonregulatory T cells upon blockage of BCL2 could add to the anti-inflammatory effect of BCL2 blockage. Collectively, our results highlight BCL2 as an important factor for GVHD development and introduce BCL2 inhibition as previously unreported and urgently needed targeted therapy in the treatment of steroid-refractory GVHD.