Minimal residual disease in chronic lymphocytic leukemia: A consensus paper that presents the clinical impact of the presently available laboratory approaches

CD160 receptor in CLL: Current state and future avenues

CD160 is a glycosylphosphatidylinositol (GPI)-anchored cell surface glycoprotein expressed on cytotoxic natural killer (NK) cells and T-cell subsets. It plays a crucial role in the activation of NK-cell cytotoxicity and cytokine production. It also modulates the immune system and is involved in some pathologies, such as cancer. CD160 is abnormally expressed in B-cell chronic lymphocytic leukemia (CLL) but not expressed in normal B lymphocytes. Its expression in CLL enhances tumor cell proliferation and resistance to apoptosis. CD160 is also a potential prognostic marker for the detection of minimal residual disease (MRD) in CLL, which is important for the clinical management of CLL, the prevention of disease relapse, and the achievement of complete remission. In this review, we present an overview of CD160 and its involvement in the pathophysiology of CLL. We also discuss its use as a prognostic marker for the assessment of MRD in CLL.

A narrative review of central nervous system involvement in acute leukemias

Acute leukemias (both myeloid and lymphoblastic) are a group of diseases for which each year more successful therapies are implemented. However, in a subset of cases the overall survival (OS) is still exceptionally low due to the infiltration of leukemic cells in the central nervous system (CNS) and the subsequent formation of brain tumors. The CNS involvement is more common in acute lymphocytic leukemia (ALL), than in adult acute myeloid leukemia (AML), although the rates for the second case might be underestimated. The main reasons for CNS invasion are related to the expression of specific adhesion molecules (VLA-4, ICAM-1, VCAM, L-selectin, PECAM-1, CD18, LFA-1, CD58, CD44, CXCL12) by a subpopulation of leukemic cells, called “sticky cells” which have the ability to interact and adhere to endothelial cells. Moreover, the microenvironment becomes hypoxic and together with secretion of VEGF-A by ALL or AML cells the permeability of vasculature in the bone marrow increases, coupled with the disruption of blood brain barrier. There is a single subpopulation of leukemia cells, called leukemia stem cells (LSCs) that is able to resist in the new microenvironment due to its high adaptability. The LCSs enter into the arachnoid, migrate, and intensively proliferate in cerebrospinal fluid (CSF) and consequently infiltrate perivascular spaces and brain parenchyma. Moreover, the CNS is an immune privileged site that also protects leukemic cells from chemotherapy. CD56/NCAM is the most important surface molecule often overexpressed by leukemic stem cells that offers them the ability to infiltrate in the CNS. Although asymptomatic or with unspecific symptoms, CNS leukemia should be assessed in both AML/ALL patients, through a combination of flow cytometry and cytological analysis of CSF. Intrathecal therapy (ITT) is a preventive measure for CNS involvement in AML and ALL, still much research is needed in finding the appropriate target that would dramatically lower CNS involvement in acute leukemia.

Let's Talk About BiTEs and Other Drugs in the Real-Life Setting for B-Cell Acute Lymphoblastic Leukemia

Background: Therapy for acute lymphoblastic leukemia (ALL) are currently initially efficient, but even if a high percentage of patients have an initial complete remission (CR), most of them relapse. Recent data shows that immunotherapy with either bispecific T-cell engagers (BiTEs) of chimeric antigen receptor (CAR) T cells can eliminate residual chemotherapy-resistant B-ALL cells.

Objective: The objective of the manuscript is to present improvements in the clinical outcome for chemotherapy-resistant ALL in the real-life setting, by describing Romania's experience with bispecific antibodies for B-cell ALL.

Methods: We present the role of novel therapies for relapsed B-cell ALL, including the drugs under investigation in phase I-III clinical trials, as a potential bridge to transplant. Blinatumomab is presented in a critical review, presenting both the advantages of this drug, as well as its limitations.

Results: Bispecific antibodies are discussed, describing the clinical trials that resulted in its approval by the FDA and EMA. The real-life setting for relapsed B-cell ALL is described and we present the patients treated with blinatumomab in Romania.

Conclusion: In the current manuscript, we present blinatumomab as a therapeutic alternative in the bridge-to-transplant setting for refractory or relapsed ALL, to gain a better understanding of the available therapies and evidence-based data for these patients in 2019.

Minimal residual disease and stem cell transplantation outcomes

Risk classification and tailoring of treatment are essential for improving outcome for patients with acute myeloid leukemia or high-risk myelodysplastic syndrome. Both patient and leukemia-specific characteristics assessed using morphology, cytogenetics, molecular biology, and multicolor flow cytometry are relevant at diagnosis and during induction, consolidation, and maintenance phases of the treatment. In particular, minimal residual disease (MRD) during therapy has potential as a prognostic factor of outcome, determination of response to therapy, and direction of targeted therapy. MRD can be determined by cell surface markers using multicolor flow cytometry, whereas leukemia-specific translocations and mutations are measured using polymerase chain reaction-based techniques and recently using next-generation sequencing. All these methods of MRD detection have their (dis)advantages, and all need to be standardized, prospectively validated, and improved to be used for uniform clinical decision making and a potential surrogate end point for clinical trials testing novel treatment strategies. Important issues to be solved are time point of MRD measurement and threshold for MRD positivity. MRD is used for stem cell transplantation (SCT) selection in the large subgroup of patients with an intermediate risk profile. Patients who are MRD positive will benefit from allo-SCT. However, MRD-negative patients have a better chance of survival after SCT. Therefore, it is debated whether MRD-positive patients should be extensively treated to become MRD negative before SCT. Either way, accurate monitoring of potential residual or upcoming disease is mandatory. Tailoring therapy according to MRD monitoring may be the most successful way to provide appropriate specifically targeted, personalized treatment.

Statistics and measurable residual disease (MRD) testing: uses and abuses in hematopoietic cell transplantation

SERIES EDITORS' NOTE

The decision whether to recommend a transplant to someone with acute leukemia in first remission is complex and challenging. Diverse, often confounded co-variates interact to influence one's recommendation. Briefly, the decision metric can be viewed in three spheres: (1) subject-; (2) transplant-; and (3) disease-related co-variates. Subject-related co-variates include items such as age and comorbidities. Transplant-related co-variates include items such as donor-types, graft source, proposed conditioning and pre- and post-transplant immune suppression.But what of disease-related variables? Previously haematologists relied on co-variates such as WBC at diagnosis, chemotherapy cycles to achieve first remission, cytogenetics and most recently, mutation topography. However, these co-variates have largely been replaced by results of measurable residual disease (MRD)-testing. Many chemotherapy-only and transplant studies report strong correlations between results of MRD-testing on therapy outcomes such as cumulative incidence of relapse (CIR), leukemia-free survival (LFS) or survival. (CIR makes biological sense in a transplant context whereas LFS and survival do not give competing causes of death such as transplant-related mortality (TRM), graft-versus-host disease and interstitial pneumonia unrelated to relapse probability).This raises the question of how useful results are of MRD-testing in predicting CIR after transplants. Elsewhere we discussed accuracy and precision of MRD-testing in predicting outcomes of therapy of acute myeloid leukemia (Estey E, Gale RP. Leukemia 31:1255-1258, 2017; Hourigan CS, Gale RP, Gormley NJ, Ossenkoppele GJ, Walter RB. Leukemia 31:1482-1490, 2017). Briefly put, not terribly good. Although results of MRD-testing are often the most powerful predictor of CIR in multivariable analyses, the C-statistic (a measure of prediction accuracy) is often only about 0.75. This is much better than flipping a fair coin but far from ideal.In the typescript which follows, Othus and colleagues discuss statistical issues underlying MRD-testing in the context of haematopoietic cell transplants. We hope readers, especially haematologists who often need to make transplant recommendations to people with acute leukemia in first remission, will read it carefully and critically. The bottom line is MRD-test data are useful but considerable uncertainty is unavoidable with substantial false-positive and -negative rates. We need to acknowledge this uncertainty to ourselves and to the people we counsel. The authors quote Voltaire who said: Doubt is not a pleasant condition, but certainty is an absurd one. Sadly so, but we do the best we can. Robert Peter Gale, Imperial College London, and Mei-Jie Zhang, Medical College of Wisconsin and CIBMTR.

LEAM vs. BEAM vs. CLV Conditioning Regimen for Autologous Stem Cell Transplantation in Malignant Lymphomas. Retrospective Comparison of Toxicity and Efficacy on 222 Patients in the First 100 Days After Transplant, On Behalf of the Romanian Society for Bone Marrow Transplantation

High-dose chemotherapy (HDT) followed by autologous hematopoietic stem cell transplantation (ASCT) is widely used in patients with malignant lymphomas. In Europe over 8,000 ASCTs for lymphoma were performed out of a total of 40,000 transplants according to the European Bone Marrow Transplant (EBMT) activity survey in 2017. ASCT is considered the standard treatment for eligible patients failing to achieve remission after first line chemotherapy or patients with relapsed or refractory lymphomas, including classical Hodkin's lymphoma, diffuse large B-cell lymphoma, mantle cell lymphoma, and follicular lymphoma, as well as consolidation therapy in first remission in mantle cell lymphoma. BEAM (BCNU/carmustine, etoposide, cytarabine, and melphalan) is the most commonly used conditioning regimen for ASCT in patients with relapsed/refractory (R/R) lymphomas in Europe, whereas the CBV (cyclophosphamide, BCNU, and etoposide) regimen is also widely used in North America. Recently, concerns regarding BCNU toxicity as well as restricted availability of BCNU and melphalan has determined an increasing number of transplant centers to use alternative conditioning regimens. Currently, only a few comparative studies, most of them retrospective, between different conditioning protocols regarding efficacy and toxicity have been published. Thus, in the current manuscript, we report the experience of 2 transplant centers in ASCT in R/R lymphomas with three types of conditioning: BEAM, CLV (cyclophosphamide, lomustine, etoposide) and LEAM (lomustine, etoposide, cytarabine, and melphalan), with the aim to evaluate the results of alternative conditioning regimens using lomustine (LEAM and CLV) and compare them with the standard BEAM regarding early toxicity, engraftment, and transplant related mortality (TRM). All patients developed grade IV neutropenia, anemia with/without transfusion necessity. Severe thrombocytopenia with transfusion requirements is reported in most cases. Median time to platelet engraftment and neutrophil engraftment was 13 days (range) and 10 days (range), respectively. Gastrointestinal toxicity was the most common non-hematologic toxicity after all three conditioning regimens. Oral mucositis in various grades from I to IV was diagnosed in most cases. Other side effects include vomiting, diarrhea, colitis, and skin rash but with low severity grades. For the LEAM arm, one patient died after transplant, before engrafting, one patient didn't achieve platelet engraftment in day 100, one patient developed grade 3 upper gastrointestinal bleeding, one patient died (grade 5 toxicity) with acute renal failure, one patient developed hypoxic events up to grade 4 acute respiratory failure and one patient developed grade 3 itchy skin rash. For the CLV arm, one patient died after transplant, before engrafting, one patient developed grade 3 colitis, one patient with grade 3 hepatic cytolysis, one patient with cardiac toxicity followed by death (grade 5) caused by an acute myocardial infarction with ST elevation and one patient with pulmonary toxicity clinically manifested with grade 3 pleurisy. For the BEAM arm, one patient developed grade 3 cardiac toxicity with sinus bradycardia and afterwards grade 4 with acute pulmonary edema, three patients presented a grade 3 pruritic skin rash and two patients developed grade 3 seizures. In the present study we presented the differences that were observed between BEAM, LEAM, and CLV conditioning regimens offering clinical arguments for an SCT practitioner choice in the ideal situation, but also of choice for alternative regimens in the case that one regimen cannot be used.

Approach to the Adult Acute Lymphoblastic Leukemia Patient

During recent decades, understanding of the molecular mechanisms of acute lymphoblastic leukemia (ALL) has improved considerably, resulting in better risk stratification of patients and increased survival rates. Age, white blood cell count (WBC), and specific genetic abnormalities are the most important factors that define risk groups for ALL. State-of-the-art diagnosis of ALL requires cytological and cytogenetical analyses, as well as flow cytometry and high-throughput sequencing assays. An important aspect in the diagnostic characterization of patients with ALL is the identification of the Philadelphia (Ph) chromosome, which warrants the addition of tyrosine kinase inhibitors (TKI) to the chemotherapy backbone. Data that support the benefit of hematopoietic stem cell transplantation (HSCT) in high risk patient subsets or in late relapse patients are still questioned and have yet to be determined conclusive. This article presents the newly published data in ALL workup and treatment, putting it into perspective for the attending physician in hematology and oncology.

Transient leukemia of Down syndrome

Childhood leukemia is mostly a "developmental accident" during fetal hematopoiesis and may require multiple prenatal and postnatal "hits". The World Health Organization defines transient leukemia of Down syndrome (DS) as increased peripheral blood blasts in neonates with DS and classifies this type of leukemia as a separate entity. Although it was shown that DS predisposes children to myeloid leukemia, neither the nature of the predisposition nor the associated genetic lesions have been defined. Acute myeloid leukemia of DS is a unique disease characterized by a long pre-leukemic, myelodysplastic phase, unusual chromosomal findings and a high cure rate. In the present manuscript, we present a comprehensive review of the literature about clinical and biological findings of transient leukemia of DS (TL-DS) and link them with the genetic discoveries in the field. We address the manuscript to the pediatric generalist and especially to the next generation of pediatric hematologists.

Clinical Approach to the Patient in Critical State Following Immunotherapy and/or Stem Cell Transplantation: Guideline for the On-Call Physician

The initial management of the hematology patient in a critical state is crucial and poses a great challenge both for the hematologist and the intensive care unit (ICU) physician. After years of clinical practice, there is still a delay in the proper recognition and treatment of critical situations, which leads to late admission to the ICU. There is a much-needed systematic ABC (Airway, Breathing, Circulation) approach for the patients being treated on the wards as well as in the high dependency units because the underlying hematological disorder, as well as disease-related complications, have an increasing frequency. Focusing on score-based decision-making on the wards (Modified Early Warning Score (MEWS), together with Quick Sofa score), active sepsis screening with inflammation markers (C-reactive protein, procalcitonin, and presepsin), and assessment of microcirculation, organ perfusion, and oxygen supply by using paraclinical parameters from the ICU setting (lactate, central venous oxygen saturation (ScVO₂), and venous-to-arterial carbon dioxide difference), hematologists can manage the immediate critical patient and improve the overall outcome.