Ofir Wolach

Late-Onset Neutropenia After Rituximab Treatment Case Series and Comprehensive Review of the Literature

Rituximab is a chimeric monoclonal antibody against CD20 that is used mainly for the treatment of CD20-positive lymphoma. Recently, its use has been expanded to include treatment of other nonmalignant diseases such as rheumatologic diseases and autoimmune cytopenia. Correlating with the increased use of rituximab has been an increased number of reports of its late adverse effects. One of these is late-onset neutropenia (LON). Most investigators define LON as grade III-IV neutropenia occurring 3-4 weeks after the last treatment with rituximab, in the absence of an alternative explanation for the neutropenia. We report 6 cases of LON identified in our institution. Four patients were treated for diffuse large B-cell lymphoma, and 2 patients for follicular lymphoma. Median patient age was 68 years (range, 33-83 yr); LON appeared after a median interval of 77 days (range, 42-153 d) and lasted for a median of 5 days (range, 1-45 d). Five of the 6 patients presented with infectious complications, and 4 patients experienced recurrent episodes of neutropenia. One patient presented with LON and concomitant subacute pulmonary disease that was attributed to rituximab therapy. In addition to our own case series we present a systematic review of the literature, which we performed to compile data to describe better the syndrome of LON. Systematic studies, case series, and case reports were extracted. Most studies dealing with LON are retrospective by design and are limited by the heterogeneous populations included in the analysis. The incidence of LON is generally reported to be in the range of 3%-27%. Data regarding populations at risk are not consistent, and in some instances are conflicting. Patients considered at increased risk of LON include patients after autologous stem cell transplantation, patients treated for acquired immunodeficiency syndrome (AIDS)-related lymphoma, and patients treated with purine analogues. Patients who received previous cytotoxic treatment as well as those treated with more intensive chemotherapy or with chemotherapy in combination with radiotherapy are also considered to be at risk of LON. In addition, advanced stages of disease and having received multiple doses of rituximab are risk factors for LON. The mechanism of LON is poorly understood. Direct toxicity is very unlikely. Some speculate that there may be an infectious etiology involved, as well as an antibody-mediated process, but these ideas have not been substantiated. The concept of a lymphocyte subpopulation imbalance leading to LON has been presented based on the demonstration of T-LGL in peripheral blood and bone marrow of patients with LON. Perturbations in stromal-derived factor-1 and in the BAFF cytokine have also been discussed as potential players in the pathogenesis of LON. A recent study correlated specific polymorphism in the immunoglobulin G Fc receptor FC&ggr;RIIIa 158 V/F with increased rates of LON. The clinical significance of LON is important because it may affect treatment strategies. Of note, infectious complications are not very frequent and not very severe. Pooling data from the major retrospective studies reveals an infection rate of 16.9%. Most infections were mild and resolved promptly. One death occurred from infection during neutropenia. Repeated episodes of LON are not uncommon, but it is so far impossible to identify those patients at risk of these relapsing episodes of LON. Re-treatment with rituximab after LON may result in recurrent episodes, but the implications and risks are uncertain at the present time. The role of growth factors once LON appears is ill defined, and the decision to use them should be made on a case-by-case basis. Abbreviations: ACVB = adriamycin, cyclophosphamide, vindesine, and bleomycin, AIDS = acquired immunodeficiency syndrome, ASCT = autologous stem cell transplantation, CT = computed tomography, DLBCL = diffuse large B-cell lymphoma, G-CSF = granulocyte colony-stimulating factor, LON = late-onset neutropenia, NHL = non-Hodgkin lymphoma, R-CHOP = rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone, R-DA-EPOCH = dose-adjusted etoposide, prednisone, vincristine, cyclophosphamide, and hydroxydaunorubicin with rituximab, SDF-1 = stromal-derived factor 1, T-LGL = T-cell large granulocyte lymphocyte.

Adolescents and young adults with acute lymphoblastic leukemia have a better outcome when treated with pediatric-inspired regimens: systematic review and meta-analysis.

Survival of adults with acute lymphoblastic leukemia (ALL) is inferior to that of pediatric patients. Strategies to improve the outcome of adult population are warranted. This study aims to evaluate the efficacy and safety of pediatric‐inspired regimens given to adolescents and young adults (AYA), usually defined as 16–39 years, with ALL. Systematic review and meta‐analysis of comparative trials of AYA patients with ALL given induction chemotherapy with either pediatric‐inspired regimens or conventional‐adult chemotherapy was conducted. Relative risks (RR) with 95% confidence intervals (CIs) were estimated and pooled. Our search yielded 11 trials, including 2,489 patients. AYA patients given pediatric‐inspired regimens had a statistically significant lower all cause mortality rate at 3 years (RR 0.58; 95% CI 0.51–0.67). Complete remission rate after induction chemotherapy and event free survival were superior in the pediatric‐inspired regimens arm (RR 1.05; 95% CI 1.01–1.10 and RR 1.66; 95% CI 1.39–1.99, respectively). Relapse rate was also lower in patients given pediatric‐inspired regimens (RR 0.51; 95% CI 0.39–0.66) with comparable nonrelapse mortality between the two groups (RR 0.53, 95% CI 0.19–1.48). Pediatric‐inspired regimens are superior to conventional‐adult chemotherapy in AYA ALL patients. Further randomized controlled studies to investigate this approach in adult ALL patients are warranted. Am. J. Hematol. 87:472–478, 2012.

Mutant Calreticulin Requires Both Its Mutant C-terminus and the Thrombopoietin Receptor for Oncogenic Transformation

UNLABELLED Somatic mutations in calreticulin (CALR) are present in approximately 40% of patients with myeloproliferative neoplasms (MPN), but the mechanism by which mutant CALR is oncogenic remains unclear. Here, we demonstrate that expression of mutant CALR alone is sufficient to engender MPN in mice and recapitulates the disease phenotype of patients with CALR-mutant MPN. We further show that the thrombopoietin receptor MPL is required for mutant CALR-driven transformation through JAK-STAT pathway activation, thus rendering mutant CALR-transformed hematopoietic cells sensitive to JAK2 inhibition. Finally, we demonstrate that the oncogenicity of mutant CALR is dependent on the positive electrostatic charge of the C-terminus of the mutant protein, which is necessary for physical interaction between mutant CALR and MPL. Together, our findings elucidate a novel paradigm of cancer pathogenesis and reveal how CALR mutations induce MPN. SIGNIFICANCE The mechanism by which CALR mutations induce MPN remains unknown. In this report, we show that the positive charge of the CALR mutant C-terminus is necessary to transform hematopoietic cells by enabling binding between mutant CALR and the thrombopoietin receptor MPL.

Neutropenia after rituximab treatment: new insights on a late complication.

Purpose of reviewLate-onset neutropenia (LON) after rituximab administration may be encountered in various clinical settings. The identification of neutropenia after rituximab treatment may have immediate implications for the clinical management of the patient and on subsequent treatment strategies. Although the pathogenesis of LON is incompletely understood, various putative mechanisms are suggested. These may be of special importance in the advent of the newer monoclonal anti-CD20 antibodies. Recent findingsThe incidence of LON varies with the clinical setting in which rituximab is administered. Administration of rituximab in the setting of stem cell transplantation significantly increases the risk for LON. The timing of rituximab administration after transplantation may affect the risk and severity of neutropenia. Recent data suggest that in rheumatologic diseases, the incidence of LON is comparable to that in the hematologic population. Suggested mechanisms for LON include humoral and cellular immune mechanisms as well processes that stem from B-cell recovery and its impact on neutrophil kinetics. Recently, an association between specific polymorphism in the immunoglobulin G Fc receptor FC&ggr;RIIIa 158 V/F and LON was demonstrated. SummaryLON is an increasingly recognized late adverse event of rituximab therapy. Acquaintance with the incidence, risk factors, natural history, and expected complications of LON may improve proper clinical management. Many aspects in the clinical management of LON remain to be answered during further studies aimed at this goal.

Infections associated with chronic granulomatous disease: linking genetics to phenotypic expression

Chronic granulomatous disease (CGD) is an inherited primary immunodeficiency characterized by the absence or malfunction of the NADPH oxidase in phagocytic cells. As a result, there is an impaired ability to generate superoxide anions and the subsequent reactive oxygen intermediates. Consequently, CGD patients suffer from two clinical manifestations: recurrent, life-threatening bacterial and fungal infections and excessive inflammatory reactions leading to granulomatous lesions. Although the genotype of CGD was linked to the phenotypic expression of the disease, this connection is still controversial and poorly understood. Certain correlations were reported, but the clinical expression of the disease is usually unpredictable, regardless of the pattern of inheritance. CGD mainly affects the lungs, lymph nodes, skin, GI tract and liver. Patients are particularly susceptible to catalase-positive microorganisms, including Staphyloccocus aureus, Nocardia spp. and Gram-negative bacteria, such as Serratia marcescens, Burkholderia cepacea and Salmonella spp. Unusually, catalase-negative microorganisms were reported as well. New antibacterial and antimycotic agents considerably improved the prognosis of CGD. Therapy with IFN-γ is still controversial. Bone marrow stem cell transplantation is currently the only curative treatment and gene therapy needs further development. In this article, the authors discuss the genetic, functional and molecular aspects of CGD and their impact on the clinical expression, infectious complications and the hyperinflammatory state.

Lymphoma and Leukemia Cells Possess Fractal Dimensions That Correlate with Their Biological Features

Background: Living cells can be viewed as complex adaptive systems that exhibit non-linear dynamics and fractal features. We investigated the fractal qualities of normal and malignant hematological cells and their potential as a tool for characterizing cell phenotype and clinical behavior. Methods: A mathematical algorithm and an optic tool for fractal analysis of nuclei were developed. A total of 4,713 lymphoid cells derived from 66 patients of five distinct diagnostic groups (normal and reactive lymphocytes, low-grade lymphomas and an aggressive lymphoma) were assessed for their fractal dimension. In addition, in 19 patients fractal analysis of leukemia cells was compared to clinical endpoints. Results: After validating our method, hematological cells possessed fractal dimensions corresponding to their clinical entity. There was a highly significant overall difference in fractal dimensions between various types of hematological malignancies. A preliminary correlation was found between the fractal dimension and the clinical outcome of leukemia patients. Conclusions: Hematological cells possess fractal dimensions that correlate with their biological properties. Measurement of fractal dimension seems to be a sensitive method to assess the hematological cell phenotype and to define a clinical group. This tool may be potentially useful for the evaluation of clinical behavior of hematological diseases.

Allogeneic transplantation is not superior to chemotherapy in most patients over 40 years of age with Philadelphia-negative acute lymphoblastic leukemia in first remission.

Survival of patients ≥40 years of age with Philadelphia‐negative acute lymphoblastic leukemia (ALL) remains poor with current therapeutic approaches. It is unknown whether allogeneic hematopoietic stem‐cell transplantation (HSCT) in first remission confers a survival benefit compared to a chemotherapy‐only approach. We retrospectively compared the outcome of patients >40 years treated with HSCT or chemotherapy alone in first remission (n = 40 in each cohort). Three‐year overall survival (OS) and disease‐free survival (DFS) were not significantly different between the chemotherapy‐only and HSCT groups (OS, 46% [31–68] vs. 40% [27–59], P = 0.35; DFS, 31% [18–52] vs. 40% [27–59], P = 0.98). The 3‐year cumulative incidence of relapse (CIR) and non‐relapse mortality (NRM) were 61% [41–76] and 9% [2–21] for the chemotherapy‐only group and 28% [15–43] and 32% [17–47] for the transplant group (CIR, P = 0.011; NRM, P = 0.014). Allogeneic transplantation for patients ≥40 years with Ph‐negative ALL in first remission is associated with a lower CIR, but this benefit is offset by considerable NRM as compared with chemotherapy‐only approach. HSCT may be beneficial in patients with high‐risk disease features. Am. J. Hematol. 91:793–799, 2016.

Differential downregulation of telomerase activity by bortezomib in multiple myeloma cells-multiple regulatory pathways in vitro and ex vivo

Background:The importance of telomerase in multiple myeloma (MM) is well established; however, its response to bortezomib has not been addressed.Methods:The effect of bortezomib on telomerase activity and cell proliferation was evaluated in four MM cell lines and in myeloma cells obtained from eight patients. The mechanism of telomerase regulation on epigenetic, transcriptional, and post-translational levels was further assessed in two selected cell lines: ARP-1 and CAG. Clinical data were correlated with the laboratory findings.Results:Bortezomib downregulated telomerase activity and decreased proliferation in all cell lines and cells obtained from patients, albeit in two different patterns of kinetics. ARP-1 cells demonstrated higher and earlier sensitivity than CAG cells due to differential phosphorylation of hTERT by PKCα. Methylation of hTERT promoter was not affected. Transcription of hTERT was similarly inhibited in both lines by decreased binding of SP-1 and not of C-Myc and NFκB. The ex vivo results confirmed the in vitro findings and suggested existence of clinical relevance.Conclusion:Bortezomib downregulates telomerase activity in MM cells both transcriptionally and post-translationally. MM cells, both in vitro and in patients, exhibit different sensitivity to the drug due to different post-translational response. The effect of bortezomib on telomerase activity may correlate with resistance to bortezomib in patients, suggesting its potential utility as a pre-treatment assessment.

Blinatumomab for the Treatment of Philadelphia Chromosome–Negative, Precursor B-cell Acute Lymphoblastic Leukemia

Blinatumomab is a CD19/CD3 bispescific antibody designed to redirect T cells toward malignant B cells and induce their lysis. It recently gained accelerated approval by the FDA for the treatment of relapsed or refractory Philadelphia chromosome–negative B-cell acute lymphoblastic leukemia (RR-ALL). In the phase II trial that served as the basis for approval, blinatumomab demonstrated significant single-agent activity and induced remission [complete remission (CR) and CR with incomplete recovery of peripheral blood counts (CRh)] in 43% of 189 adult patients with RR-ALL; the majority of responders (82%) also attained negative minimal residual disease (MRD−) status that did not generally translate into long-term remissions in most cases. Additional studies show that blinatumomab can induce high response rates associated with lasting remissions in patients in first remission treated for MRD positivity, suggesting a role for blinatumomab in the upfront, MRD-positive setting. Blinatumomab infusion follows a predictable immunopharmacologic profile, including early cytokine release that can be associated with a clinical syndrome, T-cell expansion, and B-cell depletion. Neurologic toxicities represent a unique toxicity that shares similarities with adverse effects of other T-cell engaging therapies. Further studies are needed to clarify the optimal disease setting and timing for blinatumomab therapy. Additional insights into the pathogenesis, risk factors, and prevention of neurologic toxicities as well as a better understanding of the clinical consequences and biologic pathways that are associated with drug resistance are needed. Clin Cancer Res; 21(19); 4262–9. ©2015 AACR.

Mixed-phenotype acute leukemia: current challenges in diagnosis and therapy

Purpose of review Mixed-phenotype acute leukemia (MPAL) is a rare disease that poses many diagnostic and therapeutic challenges. Patients with MPAL are considered to have poor outcomes. The difficulties in classifying this leukemia, the lack of prospectively collected data concerning therapeutic outcomes, and rare incidence result in much uncertainty as to the best approach for patients with MPAL. Recent findings Recent studies demonstrated that most MPALs are associated with cytogenetic abnormalities; genetic sequencing studies disclose a high frequency of somatic mutations in genes encoding epigenetic regulators, tumor suppressors, and transcription factors. The limited available data suggest that higher remission rates are achieved with acute lymphoblastic leukemia-like induction regimens compared with acute myeloid leukemia-type approaches. Allogeneic transplantation in first remission may be associated with improved survival compared with consolidation chemotherapy. Summary Advances in understanding the genetic landscape of MPAL may allow a more biologically driven classification of this heterogeneous group of leukemias in the future that will lead to optimized therapies for individual patients. Most data that inform therapy are based on retrospective, uncontrolled studies; prospective trials that incorporate targeted approaches based on genetics and immunophenotype are needed.