Anti-thymocyte globulin exposure in patients with diffuse cutaneous systemic sclerosis undergoing autologous haematopoietic stem cell transplantation.

Introduction: Autologous haematopoietic stem cell transplantation improves event-free survival and lung function and reduces skin thickening in patients with progressive diffuse cutaneous systemic sclerosis. Anti-thymocyte globulin is a key lymphoablative constituent of conditioning protocols and is administered in a weight-based dosage. However, whether anti-thymocyte globulin exposure contributes to response to autologous haematopoietic stem cell transplantation and lymphocyte reconstitution in diffuse cutaneous systemic sclerosis patients is unknown. We aimed to explore the relationship between anti-thymocyte globulin exposure, lymphocyte reconstitution and treatment response in diffuse cutaneous systemic sclerosis patients undergoing autologous haematopoietic stem cell transplantation. Methods: A retrospective cohort of 15 diffuse cutaneous systemic sclerosis patients undergoing autologous haematopoietic stem cell transplantation was performed. Clinical characteristics and routine laboratory results were retrieved from electronic medical records. Anti-thymocyte globulin concentrations were measured in cryopreserved plasma samples at four time points (day 1 and week 1, 2 and 4) after stem cell reinfusion. Anti-thymocyte globulin exposure was estimated using a validated population pharmacokinetic model. Results: During a median follow-up of 45 months (interquartile range 19-66), 11 (73%) patients had a treatment response, and 4 (27%) were non-responders. Although all patients received the same weight-based anti-thymocyte globulin dosage, 7.5 mg/kg divided over 3 days, anti-thymocyte globulin exposure varied. Anti-thymocyte globulin exposure was higher in responders than in non-responders (163 AU*day/mL (interquartile range 153-183) and 137 AU*day/mL (interquartile range 101-149), respectively, p = .026). Anti-thymocyte globulin exposure was not correlated with lymphocyte reconstitution or infection rate. Conclusion: Weight-based dosing of anti-thymocyte globulin results in variable anti-thymocyte globulin exposure and treatment response across individuals.

Allogeneic Stem Cell Transplantation Platforms With Ex Vivo and In Vivo Immune Manipulations: Count and Adjust.

Various allogeneic (allo) stem cell transplantation platforms have been developed over the last 2 decades. In this review we focus on the impact of in vivo and ex vivo graft manipulation on immune reconstitution and clinical outcome. Strategies include anti-thymocyte globulin- and post-transplantation cyclophosphamide-based regimens, as well as graft engineering, such as CD34 selection and CD19/αßT cell depletion. Differences in duration of immune suppression, reconstituting immune repertoires, and associated graft-versus-leukemia effects and toxicities mediated through viral reactivations are highlighted. In addition, we discuss the impact of different reconstituting repertoires on donor lymphocyte infusions and post allo pharmacological interventions to enhance tumor control. We advocate for precisely counting all graft ingredients and therapeutic drug monitoring during conditioning in the peripheral blood, and for adjusting dosing accordingly on an individual basis. In addition, we propose novel trial designs to better assess the impact of variations in transplantation platforms in order to better learn from our diversity of "counts" and potential "adjustments." This will, in the future, allow daily clinical practice, strategic choices, and future trial designs to be based on data guided decisions, rather than relying on dogma and habits.

A randomised, open-label trial to assess the optimal treatment strategy in early diffuse cutaneous systemic sclerosis: the UPSIDE study protocol.

INTRODUCTION: Systemic sclerosis (SSc) is a chronic, autoimmune connective tissue disease associated with high morbidity and mortality, especially in diffuse cutaneous SSc (dcSSc). Currently, there are several treatments available in early dcSSc that aim to change the disease course, including immunosuppressive agents and autologous haematopoietic stem cell transplantation (HSCT). HSCT has been adopted in international guidelines and is offered in current clinical care. However, optimal timing and patient selection for HSCT are still unclear. In particular, it is unclear whether HSCT should be positioned as upfront therapy or rescue treatment for patients refractory to immunosuppressive therapy. We hypothesise that upfront HSCT is superior and results in lower toxicity and lower long-term medical costs. Therefore, we propose this randomised trial aiming to determine the optimal treatment strategy for early dcSSc by comparing two strategies used in standard care: (1) upfront autologous HSCT versus (2) immunosuppressive therapy (intravenous cyclophosphamide pulse therapy followed by mycophenolate mofetil) with rescue HSCT in case of treatment failure. METHODS AND ANALYSIS: The UPSIDE (UPfront autologous hematopoietic Stem cell transplantation vs Immunosuppressive medication in early DiffusE cutaneous systemic sclerosis) study is a multicentre, randomised, open-label, controlled trial. In total, 120 patients with early dcSSc will be randomised. The primary outcome is event-free survival at 2 years after randomisation. Secondary outcomes include serious adverse events, functional status and health-related quality of life. We will also evaluate changes in nailfold capillaroscopy pattern, pulmonary function, cardiac MR and high-resolution CT of the chest. Follow-up visits will be scheduled 3-monthly for 2 years and annually in the following 3 years. ETHICS AND DISSEMINATION: The study was approved by the Dutch Central Committee on Research Concerning Human Subjects (NL72607.041.20). The results will be disseminated through patient associations and conventional scientific channels. TRIAL REGISTRATION NUMBERS: NCT04464434; NL 8720.

αß T-cell graft depletion for allogeneic HSCT in adults with hematological malignancies.

We conducted a multicenter prospective single-arm phase 1/2 study that assesses the outcome of αß T-cell depleted allogeneic hematopoietic stem cell transplantation (allo-HSCT) of peripheral blood derived stem cells from matched related, or unrelated donors (10/10 and 9/10) in adults, with the incidence of acute graft-versus-host disease (aGVHD) as the primary end point at day 100. Thirty-five adults (median age, 59; range, 19-69 years) were enrolled. Conditioning consisted of antithymocyte globulin, busulfan, and fludarabine, followed by 28 days of mycophenolic acid after allo-HSCT. The minimal follow-up time was 24 months. The median number of infused CD34+ cells and αß T cells were 6.1 × 106 and 16.3 × 103 cells per kg, respectively. The cumulative incidence (CI) of aGVHD grades 2-4 and 3-4 at day 100 was 26% and 14%. One secondary graft failure was observed. A prophylactic donor lymphocyte infusion (DLI) (1 × 105 CD3+ T cells per kg) was administered to 54% of the subjects, resulting in a CI of aGVHD grades 2-4 and 3-4 to 37% and 17% at 2 years. Immune monitoring revealed an early reconstitution of natural killer (NK) and γδ T cells. Cytomegalovirus reactivation associated with expansion of memory-like NK cells. The CI of relapse was 29%, and the nonrelapse mortality 32% at 2 years. The 2-year CI of chronic GVHD (cGVHD) was 23%, of which 17% was moderate. We conclude that only 26% of patients developed aGVHD 2-4 after αß T-cell-depleted allo-HSCT within 100 days and was associated with a low incidence of cGVHD after 2 years. This trial was registered at www.trialregister.nl as #NL4767.

Cardiovascular adverse events in patients with non-Hodgkin lymphoma treated with first-line cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) or CHOP with rituximab (R-CHOP): a systematic review and meta-analysis.

BACKGROUND: Patients treated for non-Hodgkin lymphoma are at risk of cardiovascular adverse events, with the risk of heart failure being particularly high. A regimen of cyclophosphamide, doxorubicin, vincristine, and prednisone, with (R-CHOP) or without (CHOP) rituximab is the standard first-line treatment for aggressive non-Hodgkin lymphoma, and doxorubicin and cyclophosphamide are both associated with left ventricular dysfunction. The aim of this systematic review and meta-analysis was to evaluate the cardiovascular toxicity of this regimen. METHODS: We systematically searched PubMed, EMBASE, and the Cochrane Library from database inception to June 3, 2019, for clinical trials and observational studies in adult patients with non-Hodgkin lymphoma (diffuse large B-cell lymphoma, follicular lymphoma, mantle cell lymphoma, peripheral T-cell lymphoma, and non-Hodgkin lymphoma not otherwise specified) that received first-line treatment with R-CHOP or CHOP. Studies reporting on cardiovascular adverse events and treatment-related cardiovascular mortality were included. Abstracts and articles not written in English were excluded. The main outcomes were the proportion of patients with grade 3-4 cardiovascular adverse events and heart failure. Meta-analyses of one-sample proportions were done in all patients receiving CHOP or R-CHOP. Subgroup analyses on summary estimates were done to determine the effect of number of CHOP or R-CHOP cycles, cycle interval, age, and sex. FINDINGS: Of 2314 identified entries, 137 studies (21 211 patients) published between April, 1984, and June, 2019 were eligible (9541 patients treated with CHOP, 11 293 patients treated with R-CHOP, 377 both regimens used in the study; median follow-up 39·0 months [IQR 25·5-52·8]). From the included studies, 85 subgroups were treated with CHOP, 76 with R-CHOP, and in four studies both CHOP and R-CHOP were used without a subdivision in separate groups. The pooled proportion for grade 3-4 cardiovascular adverse events, based on 77 studies (n=14 351 patients), was 2·35% (95% CI 1·81-2·93; heterogeneity test Q=326·21; τ2=0·0042; I2=71·40%; p<0·0001). For heart failure, the pooled proportion, based on 38 studies (n=5936 patients), was 4·62% (2·25-7·65; heterogeneity test Q=527·33; τ2=0·0384; I2=95·05%; p<0·0001), with a significant increase in reported heart failure from 1·64% (95% CI 0·82-2·65) to 11·72% (3·00-24·53) when cardiac function was evaluated post-chemotherapy (p=0·017). 53 (39%) of 137 studies were rated as having high risk of bias for incomplete outcome data and 54 (39%) for selective reporting. INTERPRETATION: The considerable increase of reported heart failures with cardiac monitoring, indicates that this complication often remains undiagnosed in patients with non-Hodgkin lymphoma who received first-line R-CHOP or CHOP. Our findings are of importance to raise awareness of this complication among clinicians treating patients with non-Hodgkin lymphoma and stresses the need for cardiac monitoring during and after chemotherapy. Prompt initiation of treatment for heart failure in the presymptomatic phase can mitigate the progression to more advanced heart failure stages. FUNDING: None.

Cancer Therapy-Related Cardiac Dysfunction of Nonanthracycline Chemotherapeutics: What Is the Evidence?

Cancer therapy-related cardiac dysfunction (CTRCD) is one of the most concerning cardiovascular side effects of cancer treatment. Important reviews within the field of cardio-oncology have described various agents to be associated with a high risk of CTRCD, including mitomycin C, ifosfamide, vincristine, cyclophosphamide, and clofarabine. The aim of this study was to provide insight into the data on which these incidence rates are based. We observed that the reported cardiotoxicity of mitomycin C and ifosfamide is based on studies in which most patients received anthracyclines, complicating the interpretation of their association with CTRCD. The high incidence of vincristine-induced cardiotoxicity is based on an incorrect interpretation of a single study. Incidence rates of clofarabine remain uncertain due to a lack of cardiac screening in clinical trials. The administration of high-dose cyclophosphamide (>1.5 g/m2/day) is associated with a high incidence of CTRCD. Based on our findings, a critical re-evaluation of the cardiotoxicity of these agents is warranted.

IGFBP7 Induces Differentiation and Loss of Survival of Human Acute Myeloid Leukemia Stem Cells without Affecting Normal Hematopoiesis.

Leukemic stem cells (LSCs) are thought to be the major cause of the recurrence of acute myeloid leukemia (AML) due to their potential for self-renewal. To identify therapeutic strategies targeting LSCs, while sparing healthy hematopoietic stem cells (HSCs), we performed gene expression profiling of LSCs, HSCs, and leukemic progenitors all residing within the same AML bone marrow and identified insulin-like growth factor-binding protein 7 (IGFBP7) as differentially expressed. Low IGFBP7 is a feature of LSCs and is associated with reduced chemotherapy sensitivity. Enhancing IGFBP7 by overexpression or addition of recombinant human IGFBP7 (rhIGFBP7) resulted in differentiation, inhibition of cell survival, and increased chemotherapy sensitivity of primary AML cells. Adding rhIGFBP7 reduced leukemic stem and/or progenitor survival and reversed a stem-like gene signature, but it had no influence on normal hematopoietic stem cell survival. Our data suggest a potential clinical utility of the addition of rhIGFBP7 to current chemotherapy regimens to decrease AML relapse rates.

Interleukin-2 receptor alpha-chain (CD25) expression on leukaemic blasts is predictive for outcome and level of residual disease in AML.

We investigated the role of CD25 as a prognostic marker in acute myeloid leukaemia (AML). Seventy-two newly diagnosed patients < or =60 years were retrospectively analysed by flow cytometry for CD25 positivity of AML blasts. Patients with CD25 expression of >10%, when compared to < or =10%, had a significantly shorter overall survival (OS, p=0.0005) and relapse-free survival (RFS, p=0.005). In multivariate analysis CD25 expression is an independent adverse factor for OS and RFS. High CD25 combined with FLT3-ITD positivity resulted in the poorest OS and RFS (p=0.001 and p=0.003, respectively). CD25 expression remained prognostic within the intermediate cytogenetic risk group. In addition, after the first cycle of chemotherapy, a significantly higher MRD frequency was found in patients expressing CD25 above cut-off (p=0.003). Our results show that CD25 expression is an independent adverse prognostic marker in AML patients < or =60 and correlates with MRD.

Identification of a small subpopulation of candidate leukemia-initiating cells in the side population of patients with acute myeloid leukemia.

In acute myeloid leukemia (AML), apart from the CD34(+)CD38(-) compartment, the side population (SP) compartment contains leukemic stem cells (LSCs). We have previously shown that CD34(+)CD38(-) LSCs can be identified using stem cell-associated cell surface markers, including C-type lectin-like molecule-1 (CLL-1), and lineage markers, such as CD7, CD19, and CD56. A similar study was performed for AML SP to further characterize the SP cells with the aim of narrowing down the putatively very low stem cell fraction. Fluorescence-activated cell sorting (FACS) analysis of 48 bone marrow and peripheral blood samples at diagnosis showed SP cells in 41 of 48 cases that were partly or completely positive for the markers, including CD123. SP cells in normal bone marrow (NBM) were completely negative for markers, except CD123. Further analysis revealed that the SP fraction contains different subpopulations: (a) three small lymphoid subpopulations (with T-, B-, or natural killer-cell markers); (b) a differentiated myeloid population with high forward scatter (FSC(high)) and high sideward scatter (SSC(high)), high CD38 expression, and usually with aberrant marker expression; (c) a more primitive FSC(low)/SSC(low), CD38(low), marker-negative myeloid fraction; and (d) a more primitive FSC(low)/SSC(low), CD38(low), marker-positive myeloid fraction. NBM contained the first three populations, although the aberrant markers were absent in the second population. Suspension culture assay showed that FSC(low)/SSC(low) SP cells were highly enriched for primitive cells. Fluorescence in situ hybridization (FISH) analyses showed that cytogenetically abnormal colonies originated from sorted marker positive cells, whereas the cytogenetically normal colonies originated from sorted marker-negative cells. In conclusion, AML SP cells could be discriminated from normal SP cells at diagnosis on the basis of expression of CLL-1 and lineage markers. This reveals the presence of a low-frequency (median, 0.0016%) SP subfraction as a likely candidate to be enriched for leukemia stem cells.

The novel AML stem cell associated antigen CLL-1 aids in discrimination between normal and leukemic stem cells.

In CD34(+) acute myeloid leukemia (AML), the malignant stem cells reside in the CD38(-) compartment. We have shown before that the frequency of such CD34(+)CD38(-) cells at diagnosis correlates with minimal residual disease (MRD) frequency after chemotherapy and with survival. Specific targeting of CD34(+)CD38(-) cells might thus offer therapeutic options. Previously, we found that C-type lectin-like molecule-1 (CLL-1) has high expression on the whole blast compartment in the majority of AML cases. We now show that CLL-1 expression is also present on the CD34(+)CD38(-) stem- cell compartment in AML (77/89 patients). The CD34(+)CLL-1(+) population, containing the CD34(+)CD38(-)CLL-1(+) cells, does engraft in nonobese diabetic/severe combined immunodeficiency (NOD/SCID) mice with outgrowth to CLL-1(+) blasts. CLL-1 expression was not different between diagnosis and relapse (n = 9). In remission, both CLL-1(-) normal and CLL-1(+) malignant CD34(+)CD38(-) cells were present. A high CLL-1(+) fraction was associated with quick relapse. CLL-1 expression is completely absent both on CD34(+)CD38(-) cells in normal (n = 11) and in regenerating bone marrow controls (n = 6). This AML stem-cell specificity of the anti-CLL-1 antibody under all conditions of disease and the leukemia-initiating properties of CD34(+)CLL-1(+) cells indicate that anti-CLL-1 antibody enables both AML-specific stem-cell detection and possibly antigen-targeting in future.

New approaches for the detection of minimal residual disease in acute myeloid leukemia.

The detection of minimal residual disease (MRD) in patients with acute leukemia has been studied for about 15 years by different groups in both the United States and Europe. It has been found that MRD detection can be performed using molecular and immunophenotypic aberrancies that are present in the leukemic clone at diagnosis and not in normal bone marrow. When performing MRD assessments after chemotherapy, it is possible to identify patients at risk for relapse. This review is not an overview of all MRD studies, but rather discusses the possibilities for optimizing MRD detection, the use of flow cytometry versus polymerase chain reaction techniques, and the implications for future patient treatment. When informative, we compare literature on MRD in acute myeloid leukemia (AML) with information from MRD studies in acute lymphoblastic leukemia. Finally, we address the promising detection of AML stem cells, the likely cells of origin in AML, for prediction of clinical outcome and guidance of future therapies.

High stem cell frequency in acute myeloid leukemia at diagnosis predicts high minimal residual disease and poor survival.

PURPOSE: In CD34-positive acute myeloid leukemia (AML), the leukemia-initiating event originates from the CD34(+)CD38(-) stem cell compartment. Survival of these cells after chemotherapy may lead to minimal residual disease (MRD) and subsequently to relapse. Therefore, the prognostic impact of stem cell frequency in CD34-positive AML was investigated. EXPERIMENTAL DESIGN: First, the leukemogenic potential of unpurified CD34(+)CD38(-) cells, present among other cells, was investigated in vivo using nonobese diabetic/severe combined immunodeficient mice transplantation experiments. Second, we analyzed whether the CD34(+)CD38(-) compartment at diagnosis correlates with MRD frequency after chemotherapy and clinical outcome in 92 AML patients. RESULTS: In vivo data showed that engraftment of AML blasts in nonobese diabetic/severe combined immunodeficient mice directly correlated with stem cell frequency of the graft. In patients, a high percentage of CD34(+)CD38(-) stem cells at diagnosis significantly correlated with a high MRD frequency, especially after the third course of chemotherapy. Also, it directly correlated with poor survival. In contrast, total CD34(+) percentage showed no such correlations. CONCLUSIONS: Both in vivo data, as well as the correlation studies, show that AML stem cell frequency at diagnosis offers a new prognostic factor. From our data, it is tempting to hypothesize that a large CD34(+)CD38(-) population at diagnosis reflects a higher percentage of chemotherapy-resistant cells that will lead to the outgrowth of MRD, thereby affecting clinical outcome. Ultimately, future therapies should be directed toward malignant stem cells.