Hairy cell leukemia: 2020 update on diagnosis, risk stratification, and treatment

Hairy cell leukemia - etiopathogenesis, diagnosis and modern therapeutic approach

Hairy cell leukemia (HCL) represents 2% of all leukemia cases, with men aged above 55 years being the most affected. The most common symptoms of this type of leukemia include splenomegaly, monocytopenia, and neutropenia. In the basic blood count examination, leukopenia with monocytopenia and granulocytopenia, as well as aplastic anemia and/or thrombocytopenia occur. The mutation of β-rapidly accelerated fibrosarcoma (BRAF) proto-oncogene, which can be found in nearly 100% of patients, is an important feature of HCL. Immunophenotypic analysis of the HCL cells reveals high expression of B-lineage antigens, including CD19, CD20, and CD22. Additionally, CD11c, CD25, CD103, and CD123 belong to specific markers of HCL. Lactate dehydrogenase activity and β-2-microglobulin concentration are also important in the patient's assessment. The differential diagnosis between HCL, hairy cell leukemia variant (HCL-V) and splenic marginal zone lymphoma (SMZL) is of first importance. Currently, the main treatment for HCL involves the use of purine analogues, excluding pregnant women, individuals with severe infections, and those with relapsing HCL.

Molecular Pathology of Mature Lymphoid Malignancies

Lymphoid malignancies are a broad and heterogeneous group of neoplasms. In the past decade, the genetic landscape of these tumors has been explored and cataloged in fine detail offering a glimpse into the mechanisms of lymphomagenesis and new opportunities to translate these findings into patient management. A myriad of studies have demonstrated both distinctive and overlapping molecular and chromosomal abnormalities that have influenced the diagnosis and classification of lymphoma, disease prognosis, and treatment selection.

Detangling the Threads of Hairy Cell Leukemia, Beyond the Morphology and Into the Molecular

Hairy cell leukemia (HCL) makes up 2% of leukemias in the United States and encompasses great molecular heterogeneity. The standard treatment paradigm involves purine nucleoside analogues in the upfront setting with high complete response rate to initial therapy but frequent relapses. There is an increasing role for BRAF inhibitors, with or without rituximab, in refractory and even in untreated patients. The response to purine analogues in HCL variant cases, otherwise classified as splenic lymphoma with prominent nucleolus in the 5th WHO edition classification, is less robust. Several antibodies, small molecular inhibitors, and combination regimens have been explored in HCL but data is frequently limited by case reports or small case series. Here we review available treatment options including their efficacy and safety profiles. We also explore investigational agents and potential future targets. The goal is to present a comprehensive therapeutic review of this rare disease entity and outline the ever increasing and novel therapeutic management options which interrupt key pathways in the pathogenesis of this malignancy.

Enhancing Efficacy and Quality of Life in Patients with Herpes Zoster Infection in Hairy Cell Leukemia

Hairy cell leukemia (HCL) is an infrequent and persistent B-cell inert lymphoid leukemia. In this study, we present the case of a 71-year-old female patient with a previous diagnosis of variant HCL who experienced a severe herpes zoster infection leading to an extensive skin eruption. The patient's initial diagnosis of HCL occurred 7 years ago, and she underwent treatment with cladribine, interferon, COP (cyclophosphamide, vincristine, and prednisone), benztropine tablets + clarithromycin dispersible, and ibrutinib. Immune disorders resulting from repeated prior chemotherapy and targeted therapy may potentially precipitate herpes zoster infection. Despite an initial two-week period of unresponsiveness to antivirals and nerve nutrition treatments, the introduction of topical Coptis liquid to the treatment regimen yielded significant efficacy. This case report underscores the potential of Chinese medicine as an adjunct to conventional antiviral therapy in the management of herpes zoster infection in immunocompromised patients. This treatment protocol has the potential to enhance efficacy, enhance quality of life, and serve as a more robust foundation for clinical diagnosis and improved treatments.

The course of patients with hairy cell leukemia during the omicron surge of the Covid-19 pandemic

In this study, we aim to explore the outcomes of Covid-19 infection in patients with Hairy cell leukemia (HCL). The cohort is based on data obtained from electronic medical records. It includes 218 consecutive patients diagnosed with HCL between 16 June 1998, and 20 September 2022, out of which the coronavirus has infected 85 patients during the Omicron surge. Out of 85 patients with HCL who were infected by Covid-19; 7 patients (8.2%) have been hospitalized, and the mortality rate was 2.3% (two patients). Thirteen of the 85 patients had been infected by Covid-19 in previous waves, including 9/13 after vaccination, and none of them developed a severe disease. Humoral immune response after three doses of the BNT162b2 mRNA vaccination regimen was evaluated in 40 patients and was attained in 67.5%. Based on multivariate analysis: unfavorable outcome was significantly more common in patients with HCL above 65 years old, who had at least one cytopenia, and with comorbidity of cardiovascular disease or asplenia. Our results indicates that the course of COVID-19 in patients with HCL during the Omicron wave has been improved relatively favorable.

Long term follow-up of refractory/relapsed hairy cell leukaemia patients treated with low-dose vemurafenib between 2013 and 2022 at the Department of Internal Medicine and Oncology, Semmelweis University

Introduction: Hairy cell leukemia (HCL) is an indolent B-cell lymphoproliferative disease. BRAF V600E mutation is detected in nearly all classical HCL cases which offers the possibility of targeted therapy. Objective: The aim of our study was to assess the efficacy of low-dose vemurafenib as well as to assess the long term outcome of HCL patients treated with this drug at the Department of Internal Medicine and Oncology at Semmelweis University. Methods: We report on 10 patients with classical HCL treated with low-dose vemurafenib at our Department between 2013 and 2022. Results: As a result of fixed time low-dose vemurafenib treatment, 5 of 10 patients (5/10) achieved partial remission, 4 (4/10) had stable disease, and 1 (1/10) had MRD positivity. No patients achieved complete remission. The median progression-free survival was 28.5 months while the overall survival was 82 months. Conclusion: We confirm that low dose of vemurafenib is effective and safe in the vast majority of patients with HCL. This small-molecule oral treatment allows to gain valuable time-months or even years-before further, usually parenteral treatment options have to be given or before previous treatment has to be repeated. There are also promising data supporting the combination of vemurafenib with other drugs for the treatment of HCL patients which could provide even further possibility to bridge treatment.

Flow Cytometry of CD5-Positive Hairy Cell Leukemia

BACKGROUND AND OBJECTIVE

Hairy cell leukemia (HCL) is a chronic lymphoproliferative disorder for which diagnosis is typically straightforward, based on bone marrow morphology and flow cytometry (FC) or immunohistochemistry. Nevertheless, variants present atypical expressions of cell surface markers, as is the case of CD5, for which the differential diagnosis can be more difficult. The aim of the current paper was to describe diagnosis of HCL with atypical CD5 expression, with an emphasis on FC.

METHODS

The detailed diagnostic methodology for HCL with atypical CD5 expression is presented, including differential diagnosis from other lymphoproliferative diseases with similar pathologic features, by FC analysis of the bone marrow aspirate.

RESULTS

Diagnosis of HCL by means of FC started by gating all events based on side scatter (SSC) versus CD45 and B lymphocytes were selected from the lymphocytes gate as CD45/CD19 positive. The gated cells were positive for CD25, CD11c, CD20, and CD103, while CD10 proved to be dim to negative. Moreover, cells positive for CD3, CD4, and CD8, the three pan-T markers, as well as CD19, showed a bright expression of CD5. The atypical CD5 expression is usually correlated with a negative prognosis and thus chemotherapy with cladribine should be initiated.

CONCLUSION

HCL is an indolent chronic lymphoproliferative disorder and diagnosis is usually straightforward. However, atypical expression of CD5 renders its differential diagnosis more difficult, but FC is a useful tool that allows an optimal classification of the disease and allows initiation of timely satisfactory therapy.

Hairy Cell Leukemia: Hepatic Affinity Status Post Splenectomy

Hairy cell leukemia (HCL) is a rare neoplasm of the B-cell lineage that is characterized by an indolent course and infiltration of the spleen, the bone marrow, and the reticuloendothelial system. Splenectomy is considered an effective treatment for peripheral cytopenia in patients with HCL. Hepatic involvement of hairy cells with infiltration of the sinusoidal endothelial cells is rarely reported in the literature and is not well understood. We present the case of an 88-year-old male with a history of traumatic splenectomy who was found to have a relapse of classic hairy cell leukemia within the hepatic portal system.

Atraumatic Splenic Rupture as an Unusual Presentation of Hairy Cell Leukemia: A Case Report

Hairy cell leukemia (HCL) represents a rare B-cell malignancy with 2% of all leukemias and should be differentiated from HCL-like conditions, including HCL-variant (HCL-V) and splenic diffuse red pulp lymphoma (SDRPL). HCL gets its name from the short, thin projections that look like hair on its cells. It is associated with a specific immunophenotypic profile, cytopenia, and splenomegaly. Spontaneous splenic rupture can be a symptom of hematological malignancy such as HCL and is a life-threatening acute emergency. Here, we present a case of a 37-year-old man who presented to the hospital with signs of acute peritonitis and acute anemia and was found to have atraumatic splenic rupture secondary to splenomegaly. He underwent emergent angiography, where the bleeding splenic vessel was identified, and the patient was successfully treated with embolization. Immunophenotypic profile revealed that B-cells were positive for CD11c, CD103, CD25, and CD5, for which he received five days of cladribine and achieved complete clinical remission.

Hairy cell leukemia with isolated bone lesions

Key Clinical Message

¹⁸F-FDG PET/CT has clinical relevance in HCL at diagnosis and for the follow-up of patients treated, especially in case of atypical presentations such as bone involvements (which are probably underestimated) and poor bone marrow infiltration.

Abstract

Bone lesions are rarely reported in Hairy Cell Leukemia (HCL). We report two BRAF^V600E mutated HCL patients presented bone lesions at foreground, poor bone marrow involvement, and the important role ¹⁸F-FDG PET/CT played in their management. We discuss the crucial role that ¹⁸F-FDG PET/CT could play in HCL routine practice.

Hairy Cell Leukemia (HCL) Presenting with Joint Swelling: Case Report and Literature Review of a Rare Rheumatological Manifestation of a Hematological Disease

Hairy cell leukemia (HCL) is a rare malignancy that primarily affects the bone marrow, peripheral blood, and spleen. The most common presenting features of HCL are splenomegaly or cytopenias causing fatigue, infections, or hemorrhagic manifestations. Symptoms involving the soft tissue or bone are rare. HCL can rarely present with immune-mediated polyarthritis. This presentation can be confused for other pathological entities, such as Felty's syndrome, and can be differentiated from this with bone marrow biopsy. This case report looks into a rare presentation of HCL in which transient polyarthritis of the knees was the presenting symptom.

Long-term follow-up of patients with hairy cell leukemia in the south of Iran

BACKGROUND

Hairy cell leukemia (HCL) is an indolent chronic lymphoproliferative disorder and first-line treatment with either intravenous or subcutaneous cladribine generally leads to long-lasting remissions.

METHOD

All 131 patients with hairy-cell leukemia (HCL) were analyzed, with a median follow-up of 91 months. Data is from 2007 to 2020. We evaluated the response rate to cladribine as the first line and the response rate to cladribine with or without rituximab in relapsed patients. Further, we assessed relapse-free survival, complications, and secondary malignancy.

RESULTS

After a median follow-up of 91 months, the recurrence rate was 24%. The 5-year and 10-year RFS rates were 85% and 66%, respectively. Adding rituximab to 2-CDA leads to a better response rate than just cladribine (90% vs. 27.3%, p-value = 0.002) in the relapsed patients.

CONCLUSION

HCL patients have long-term survival when cladribine is the first line of treatment. Furthermore, adding rituximab to cladribine leads to a higher response rate.

A Frail Hairy Cell Leukemia Patient Successfully Treated with Pegylated Interferon-α-2A

Hairy cell leukemia (HCL) treatment in elderly, frail subjects is still unsatisfactory, and interferons, old-fashioned therapies, can be effectively used in this subset of patients. Here, to the best of our knowledge, we report for the first time an old, frail HCL patient effectively and safely treated with pegylated interferon-α-2a in monotherapy as a first-line treatment. At diagnosis, the patient arrived in a life-threating condition due to severe neutropenia and splenomegaly with high risk of splenic rupture. However, splenectomy was proposed and refused by the patient; therefore, a therapy with pegylated interferon-α-2a was initiated. After six months of therapy, the patient displayed the disappearance of palpable splenomegaly and of peripheral hairy cells at morphological examination without any drug-related adverse event. Our case report supports the use of pegylated interferon-α-2a in monotherapy as an effective and safe alternative therapeutic option in frail, elderly patients not eligible for purine analogous or targeted therapies.

Hodgkin Lymphoma and Hairy Cell Leukemia Arising from Chronic Lymphocytic Leukemia: Case Reports and Literature Review

Richter’s syndrome represents the progression of chronic lymphocytic leukemia (CLL) to more aggressive diseases, most frequently diffuse large B-cell lymphoma, while Hodgkin’s lymphoma (HL) and hairy cell leukemia (HCL) are rarely described. The first case involved a 67-year-old man with a diagnosis of a high-risk stage-II CLL treated with rituximab and ibrutinib, developed a HL nodular sclerosis variant after three months of therapy for CLL. After achieving a complete remission for HL and ibrutinib cessation because of drug-related cardiotoxicity, the patient relapsed after five months off-therapy and died due to disease progression after two cycles of brentuximab-vedotin. The second case involved an 83-year-old female with a diagnosis of stage-IV CLL treated with rituximab plus bendamustine who developed a HCL eight years later. Pentostatin was unsuccessfully employed as upfront HCL therapy, and the patient was then switched to rituximab while in remission for CLL. In conclusion, Richter’s transformation risk rate might be higher in patients treated with novel targeted therapies, and multiparametric flow cytometry and lymph node biopsy at relapse could help in early identifying small clones. The treatment of predominant neoplasia is mandatory, and disease-specific drugs are administered; however, clinical efficacy might be lower in these patients.

Long-term follow-up of cladribine treatment in hairy cell leukemia: 30-year experience in a multicentric Italian study

Hairy cell leukemia (HCL) is a rare lymphoproliferative disease with an excellent prognosis after treatment with cladribine (2CDA), although relapse may occur during follow-up. The aim of the study is to review the efficacy, safety, long-term remission rate, and overall survival (OS) in those patients who received 2CDA as first-line treatment. We retrospectively reviewed data of HCL patients treated with 2CDA between March 1991 and May 2019 at 18 Italian Hematological centers: 513 patients were evaluable for study purpose. The median age was 54 years (range 24–88) and ECOG was 0 in 84.9% of cases. A total of 330 (64.3%) patients received 2CDA intravenously and 183 (35.7%) subcutaneously. ORR was 91.8%: CR was obtained in 335 patients (65.3%), PR in 96 (18.7%), and hematological response in 40 (7.8%) patients; in 42 (8.2%) no response was observed. Hemoglobin value (p = 0.044), frequency of circulating hairy cells (p = 0.039), recovery of absolute neutrophil count (p = 0.006), and normalization of spleen (p ≤ 0.001) were associated with CR compared to PR in univariable analysis. At a median follow-up of 6.83 years (range 0.04–28.52), the median time to relapse was 12.2 years. A significant difference in duration of response was identified between patients that obtained a CR and PR (19.4 years versus 4.8 years, p < 0.0001). Non-hematological grade 3 or higher early toxicity was reported in 103 (20.1%) patients. Median OS was not reached: 95.3%, 92.4%, and 81.8% of patients were estimated to be alive at 5, 10, and 15 years, respectively. Forty-nine patients died (9.5%), following an infection in 14 cases (2.7%), natural causes in 14 (2.7%), cardiovascular events in 13 (2.5%), a second neoplasm in 6 (1.2%), and progression of HCL in 2 cases (0.4%). Following treatment of HCL with 2CDA, 80% of patients are estimated to be alive 15 years after diagnosis.

Digital Droplet PCR in Hematologic Malignancies: A New Useful Molecular Tool

Digital droplet PCR (ddPCR) is a recent version of quantitative PCR (QT-PCR), useful for measuring gene expression, doing clonality assays and detecting hot spot mutations. In respect of QT-PCR, ddPCR is more sensitive, does not need any reference curve and can quantify one quarter of samples already defined as "positive but not quantifiable". In the IgH and TCR clonality assessment, ddPCR recapitulates the allele-specific oligonucleotide PCR (ASO-PCR), being not adapt for detecting clonal evolution, that, on the contrary, does not represent a pitfall for the next generation sequencing (NGS) technique. Differently from NGS, ddPCR is not able to sequence the whole gene, but it is useful, cheaper, and less time-consuming when hot spot mutations are the targets, such as occurs with IDH1, IDH2, NPM1 in acute leukemias or T315I mutation in Philadelphia-positive leukemias or JAK2 in chronic myeloproliferative neoplasms. Further versions of ddPCR, that combine different primers/probes fluorescences and concentrations, allow measuring up to four targets in the same PCR reaction, sparing material, time, and money. ddPCR is also useful for quantitating BCR-ABL1 fusion gene, WT1 expression, donor chimerism, and minimal residual disease, so helping physicians to realize that "patient-tailored therapy" that is the aim of the modern hematology.

Remarkable Response of Hairy Cell Leukemia Variant to Single-Agent Cladribine

Classical hairy cell leukemia (cHCL) and related mature lymphoid B-cell neoplasms including hairy cell leukemia variant (HCLv) and splenic diffuse red pulp lymphoma (SDRPL) are a rare subset of lymphoid neoplasms. cHCL accounts for around 2% of all leukemias and is characterized by a peripheral smear with large lymphoid cells with cytoplasmic projections giving the cells a hairy appearance, splenomegaly, and cytopenias. Majority of cHCL cases harbor a BRAFV600E mutation. cHCL usually responds well to single-agent purine analogs. HCLv is even rarer and constitutes around 0.4% of lymphoid malignancies. Unlike cHCL, HCLv is less responsive to standard single-agent purine analogs and typically does not harbor the BRAFV600E mutation. The “hairy cells,” splenomegaly, and cytopenias are common in both. We report a case of a patient with HCLv who was treated with a single purine analog and achieved a near-complete response.

Prompt Hematological Recovery in Response to a Combination of Pegylated Interferon α-2a and Rituximab in a Profoundly Immuno-Suppressed Hairy Cell Leukemia Patient with a Mycobacterial Infection at Onset: Benefits and Drawbacks of Rapid Immune Reconstitution

The present paper reports, to the best of our knowledge for the first time, the efficacy and tolerability of the combination of interferon (IFN)α-2a in pegylated formulation and rituximab after a “priming” phase with IFN in the frontline treatment of hairy cell leukemia (HCL) in a profoundly immunosuppressed patient with a Mycobacterium abscessus infection at onset. This immunotherapy combination may represent a potential therapeutic option in patients with active severe infection and for whom the use of purine nucleoside analogues (PNA) is contraindicated. The benefits and drawbacks of remarkably rapid immune reconstitution in the context of opportunistic infections are highlighted as well, as the potentially paradoxical effects of immune recovery as a result of effective immunotherapy strategies, known as immune reconstitution inflammatory syndrome (IRIS), have to be taken into account when dealing with patients with opportunistic infections.

BRAF-Mutated Non-Small Cell Lung Cancer: Current Treatment Status and Future Perspective

V-Raf murine sarcoma viral oncogene homolog B (BRAF) kinase, which was encoded by BRAF gene, plays critical roles in cell signaling, growth, and survival. Mutations in BRAF gene will lead to cancer development and progression. In non-small cell lung cancer (NSCLC), BRAF mutations commonly occur in never-smokers, women, and aggressive histological types and accounts for 1%-2% of adenocarcinoma. Traditional chemotherapy presents limited efficacy in BRAF-mutated NSCLC patients. However, the advent of targeted therapy and immune checkpoint inhibitors (ICIs) have greatly altered the treatment pattern of NSCLC. However, ICI monotherapy presents limited activity in BRAF-mutated patients. Hence, the current standard treatment of choice for advanced NSCLC with BRAF mutations are BRAF-targeted therapy. However, intrinsic or extrinsic mechanisms of resistance to BRAF-directed tyrosine kinase inhibitors (TKIs) can emerge in patients. Hence, there are still some problems facing us regarding BRAF-mutated NSCLC. In this review, we summarized the BRAF mutation types, the diagnostic challenges that BRAF mutations present, the strategies to treatment for BRAF-mutated NSCLC, and resistance mechanisms of BRAF-targeted therapy.

Adamantiades-Behçet disease: from clinical heterogeneity to diagnosis during the COVID-19 pandemic

Adamantiades-Behçet Disease (ABD) is a systemic disease with vasculitis, characterised by recurrent oral aphthosis and ocular, cutaneous, articular, vascular, cardiopulmonary manifestations and it is mainly found in the territories of the antique "silk road. ABD pathogenesis remains unknown although genetic, infectious and environmental factors seem to be implicated in the development of the disease, which is considered an auto-inflammatory condition. COVID-19 infection can present some symptoms, in particular at the level of oral and pulmonary mucosa, which require a differential diagnosis with ABD. Furthermore, the immunological alterations of this disease, and the drugs used for its treatment could influence the infection by COVID-19, and its clinical evolution. Nevertheless, vaccination anti-COVID-19 is recommended in ABD patients. The most commonly used diagnostic criteria for ABD are those established in 2014 by the International Team for the Revision of the International Criteria for BD (ITR-ICBD). Furthermore, criteria for disease severity according to the Overall Damage Index of Behçet's syndrome (BODI) have recently been proposed in order to quantify the severity of the disease as well as the evolution during follow-up. In ABD patients it is mandatory to investigate on the presence of active/latent tuberculosis, because of the common organ involvement, such as eyes and bowel. ABD has a high morbidity and low mortality, sometimes linked to the rupture of an arterial aneurysm and/or neurological complications. This article is based on a general review on ABD ranging from the history of ABD to possible causes and clinical manifestations. A specific section has been dedicated to the COVID-19 pandemic.

Advances in the Treatment of Hairy Cell Leukemia Variant

OPINION STATEMENT

Hairy cell leukemia variant (HCL-V) is a rare B cell lymphoproliferative disorder with a clinical-pathological distinction from the classic form of hairy cell leukemia (HCL-C). HCL-V is more aggressive in nature, has a higher tendency to be refractory to conventional purine analog pharmacotherapies, and leads to a poorer prognosis. Hence, these differing features bring paramount importance to the diagnosis and management of HCL-V. While there is no genetic mutation diagnostic of HCL-V, genetic profiling efforts have identified potential therapeutic targets (i.e., MAP2K1, KDM6A, CREBBP, ARID1A, CCND3, U2AF1, KMT2C) and yielded prognostic markers (i.e., IGHV4-34 rearrangements). To date, combination chemoimmunotherapies, such as cladribine and rituximab, have shown the best results in HCL-V. Future directions include targeted therapies such as moxetumomab pasudotox, ibrutinib, trametinib, and binimetinib and potentially anti-CD22 chimeric antigen receptor T cell therapy. The purpose of this review is to provide an outline of the diagnostic approach and an update on the therapeutic advancements in HCL-V.

The Genomics of Hairy Cell Leukaemia and Splenic Diffuse Red Pulp Lymphoma

Classical hairy cell leukaemia (HCLc), its variant form (HCLv), and splenic diffuse red pulp lymphoma (SDRPL) constitute a subset of relatively indolent B cell tumours, with low incidence rates of high-grade transformations, which primarily involve the spleen and bone marrow and are usually associated with circulating tumour cells characterised by villous or irregular cytoplasmic borders. The primary aim of this review is to summarise their cytogenetic, genomic, immunogenetic, and epigenetic features, with a particular focus on the clonal BRAFV600E mutation, present in most cases currently diagnosed with HCLc. We then reflect on their cell of origin and pathogenesis as well as present the clinical implications of improved biological understanding, extending from diagnosis to prognosis assessment and therapy response.

A Case of Hemophagocytic Lymphohistiocytosis Triggered by Disseminated Tuberculosis and Hairy Cell Leukaemia after SARS-CoV2 Infection

Hemophagocytic Lymphohistiocytosis (HLH) is a rare but life-threatening disease that can occur either as a primary condition or as a consequence of a variety of triggers, including infectious diseases. Here we present a case of secondary HLH triggered by systemic Mycobacterium tuberculosis infection in a 59-year-old immunocompromised Hairy Cell Leukemia and previous SARS-CoV2 infected patient. This case report underlines the role of Etoposide-based chemotherapy in treating the severe inflammation that is the defining factor of HLH, suggesting how, even when such therapy is not effective, it may still give the clinicians time to identify the underlying condition and start the appropriate targeted therapy. Moreover, it gives insight on our decision to treat the underlying haematological condition with a BRAF-targeted therapy rather than purine analog-based chemotherapy to reduce the risk of future severe infections.

Different Susceptibility of T and B Cells to Cladribine Depends On Their Levels of Deoxycytidine Kinase Activity Linked to Activation Status

Deoxycytidine kinase (dCK) and 5' deoxynucleotidase (NT5C2) are involved in metabolism of cladribine (2CdA), the immunomodulatory drug for multiple sclerosis; by mediating phosphorylation (activation) or phosphorolysis (deactivation) of 2CdA, respectively, these enzymes promote or prevent its accumulation in the cell, which leads to cell death. In particular, lymphocytes which present with a high intracellular dCK/NT5C2 ratio are more sensitive to 2CdA than other immune cells. We aim at determining if the expression of these enzymes and/or their activity differ in specific progenitor and mature immune cells and are influenced by cellular activation and/or exposure to 2CdA. Flow cytometry analysis showed no difference in dCK/NT5C2 ratio in progenitor and mature immune cells. 2CdA induced apoptosis in stimulated T and B cells and unstimulated B cells. dCK expression was enhanced by 2CdA at mRNA and protein levels in activated T cells and mRNA level in activated B cells. dCK activity, measured through an in-house luminescence release enzyme assay was higher in activated T and B cells, and such an increase was abrogated in activated B cells, but not T cells, upon exposure to 2CdA. These results reveal an important relationship between dCK activity and the effect of 2CdA on B and T cells, according to their activation status. Further study is warranted to evaluate whether dCK activity could, in the future, be a suitable predictive biomarker of lymphocyte response to 2CdA.

Ovarian cancer subtypes based on the regulatory genes of RNA modifications: Novel prediction model of prognosis

BACKGROUND

Ovarian cancer (OC) is a female reproductive system tumor. RNA modifications play key roles in gene expression regulation. The growing evidence demonstrates that RNA methylation is critical for various biological functions, and that its dysregulation is related to the progression of cancer in human.

METHOD

OC samples were classified into different subtypes (Clusters 1 and 2) based on various RNA-modification regulatory genes (RRGs) in the process of RNA modifications (m1A, m6A, m6Am, m5C, m7G, ac4C, m3C, and Ψ) by nonnegative matrix factorization method (NMF). Based on differently expressed RRGs (DERRGs) between clusters, a pathologically specific RNA-modification regulatory gene signature was constructed with Lasso regression. Kaplan-Meier analysis and receiver operating characteristic (ROC) curves were used to evaluate the prognostic ability of the identified model. The correlations of clinicopathological features, immune subtypes, immune scores, immune cells, and tumor mutation burden (TMB) were also estimated between different NMF clusters and riskscore groups.

RESULTS

In this study, 59 RRGs in the process of RNA modifications (m1A, m6A, m6Am, m5C, m7G, ac4C, m3C, and Ψ) were obtained from TCGA database. These RRGs were interactional, and sample clusters based on these regulators were significantly correlated with survival rate, clinical characteristics (involving survival status and pathologic stage), drug sensibility, and immune microenvironment. Furthermore, Lasso regression based on these 21 DERRGs between clusters 1 and 2 constructed a four-DERRG signature (ALYREF, ZC3H13, WTAP, and METTL1). Based on this signature, 307 OC patients were classified into high- and low-risk groups based on median value of riskscores from lasso regression. This identified signature was significantly associated with overall survival, radiation therapy, age, clinical stage, cancer status, and immune cells (involving CD4+ memory resting T cells, plasma cells, and Macrophages M1) of ovarian cancer patients. Further, GSEA revealed that multiple biological behaviors were significantly enriched in different groups.

CONCLUSIONS

OC patients were classified into two subtypes per these RRGs. This study identified four-DERRG signature (ALYREF, ZC3H13, WTAP, and METTL1) in OC, which was an independent prognostic model for patient stratification, prognostic evaluation, and prediction of response to immunotherapy in ovarian cancer by classifying OC patients into high- and low-risk groups.

CD103-CD23+ classical hair cell leukemia: A case report and review of the literature

INTRODUCTION

This case report is presented to improve our understanding of the atypical immunophenotype of hairy cell leukemia.

PATIENT CONCERNS

A 58-year-old woman presented to our department with fatigue for >10 days.

DIAGNOSIS

The patient was diagnosed with an increased proportion of abnormal lymphocytes in peripheral blood and bone marrow smear, positive for CD11c, CD19, CD20, CD22, CD25, CD123, CD200, and Kappa, partial expression of CD23, but no expression of CD103, positive for BRAF V600E mutation.

INTERVENTIONS AND OUTCOMES

Cladribine combined with rituximab achieved complete remission of minor residual disease negativity.

CONCLUSION

Hairy cell leukemia is rare, and the diagnosis and differential diagnosis should be made by combining the patient's medical history, clinical manifestations, immunophenotype, gene detection, and other means. Purine nucleoside analogs are the first-line treatments.

How to Diagnose and Treat CD5-Positive Lymphomas Involving the Spleen

Patients with CD5-expressing lymphomas presenting with splenomegaly are frequently diagnosed with chronic lymphocytic leukemia. The most important differential diagnosis is mantle cell lymphoma, both in its classical and leukemic, non-nodal forms, given its prognostic and therapeutic implications. Other small B-cell neoplasms that frequently involve the spleen and occasionally express CD5 include the splenic marginal zone lymphoma, hairy cell leukemia and, rarely, lymphoplasmacytic lymphoma. The frequency of CD5 positivity depends in part on the sensitivity of the detection methods employed. Usually, a combination of morphological, immunophenotypic and molecular findings allows for a precise sub-classification of CD5-positive, low-grade B-cell lymphomas of the spleen. Some of these tumors may display a mixture of small and larger B cells, raising the possibility of more aggressive lymphomas, such as diffuse large B-cell lymphomas (DLBCL). Approximately 5-10% of DLBCL are CD5-positive and some may manifest as primary splenic lesions. When available, the morphology of DLBCL in the splenic tissue is distinctive and a leukemic picture is very rare. In conclusion, the appropriate morphological and clinical context assisted by flow cytometry panels and/or immunohistochemistry allows the differential diagnosis of CD5-positive, non-Hodgkin, B-cell lymphomas involving the spleen.

Rituximab Treatment of Hairy Cell Leukemia in a Patient with Mycobacterium kansasii Infection: A Case Report

INTRODUCTION

Infectious complications represent a major cause of morbidity and mortality in hairy cell leukemia (HCL) patients. Due to the immunosuppressive nature of the disease, these patients are frequently affected by opportunistic infections and rare pathogens. Furthermore, cytotoxic chemotherapy might lead to poor or even fatal outcomes in the setting of an active infection.

CASE PRESENTATION

We report the case of a 62-year-old HCL patient who presented with recurrent fever episodes, pancytopenia, and mediastinal lymphadenopathy. A treatment decision against purine analogs and for rituximab mono was made as lymph node tissue revealed disseminated Mycobacterium kansasii infection. Together with specific antimycobacterial treatment, rituximab mono led to complete hematologic remission after 6 months without aggravating the accompanying infection.

CONCLUSION

Here, we demonstrate successful treatment of HCL with rituximab in a patient with concomitant disseminated M. kansasii infection.

Clinical Utility of Targeted Next-Generation Sequencing in the Evaluation of Low-Grade Lymphoproliferative Disorders

OBJECTIVES

We investigated the usefulness of a custom-designed 31-gene next-generation sequencing (NGS) panel implemented on a routine basis for the evaluation of low-grade lymphoproliferative disorders (LPDs).

METHODS

In total, 147 blood, bone marrow, and tissue specimens were sequenced, including 81% B-cell, 15% T-cell, and 3% natural killer (NK)-cell neoplasms.

RESULTS

Of the cases, 92 (63%) of 147 displayed at least one pathogenic variant while 41 (28%) of 147 had two or more. Low mutation rates were noted in monoclonal B-cell lymphocytoses and samples with small T- and NK-cell clones of uncertain significance. Pathogenic molecular variants were described in specific disorders and classified according to their diagnostic, prognostic, and potential therapeutic value. Diagnostically, in addition to confirming the diagnosis of 15 of 15 lymphoplasmacytic lymphomas, 10 of 12 T large granular lymphocytic leukemias, and 2 of 2 hairy cell leukemias (HCLs), the panel helped resolve the diagnosis of 10 (62.5%) of 16 challenging cases lacking a specified diagnosis based on standard morphology, phenotype, and genetic analysis.

CONCLUSIONS

Overall, implementation of this targeted lymphoid NGS panel as part of regular hematopathology practice was found to be a beneficial adjunct in the evaluation of low-grade LPDs.

In Vitro Sensitivity to Venetoclax and Microenvironment Protection in Hairy Cell Leukemia

Current standard treatment of patients with hairy cell leukemia (HCL), a chronic B-cell neoplasia of low incidence that affects the elderly, is based on the administration of purine analogs such as cladribine. This chemotherapy approach shows satisfactory responses, but the disease relapses, often repeatedly. Venetoclax (ABT-199) is a Bcl-2 inhibitor currently approved for the treatment of chronic lymphocytic leukemia (CLL) and acute myeloid leukemia (AML) in adult patients ineligible for intensive chemotherapy. Given that HCL cells express Bcl-2, our aim was to evaluate venetoclax as a potential therapy for HCL. We found that clinically relevant concentrations of venetoclax (0.1 and 1 µM) induced primary HCL cell apoptosis in vitro as measured by flow cytometry using Annexin V staining. As microenvironment induces resistance to venetoclax in CLL, we also evaluated its effect in HCL by testing the following stimuli: activated T lymphocytes, stromal cells, TLR-9 agonist CpG, and TLR-2 agonist PAM3. We found decreased levels of venetoclax-induced cytotoxicity in HCL cells exposed for 48 h to any of these stimuli, suggesting that leukemic B cells from HCL patients are sensitive to venetoclax, but this sensitivity can be overcome by signals from the microenvironment. We propose that the combination of venetoclax with drugs that target the microenvironment might improve its efficacy in HCL.

Molecular Pathology of Mature Lymphoid Malignancies

Lymphoid malignancies are a broad and heterogeneous group of neoplasms. In the past decade, the genetic landscape of these tumors has been explored and cataloged in fine detail offering a glimpse into the mechanisms of lymphomagenesis and new opportunities to translate these findings into patient management. A myriad of studies have demonstrated both distinctive and overlapping molecular and chromosomal abnormalities that have influenced the diagnosis and classification of lymphoma, disease prognosis, and treatment selection.

[Hairy cell leukemia: What are the best treatment options for relapsed or refractory patients?]

Hairy cell leukemia is a rare form of leukemia: three hundred new cases are diagnosed each year in France. The diagnosis is based on: (1) morphological examination of the blood and bone marrow smear, (2) analysis by flow cytometry of hairy cells, which express three or the four following markers: CD11c, CD25, CD103 and CD123, (3) identification of the BRAF^V600E mutation, a true molecular marker of the disease. The management of treatment has evolved considerably in recent years. As of today, the purine analogues remain the standard treatment in the first line. Relapses are however observed in about 40% of cases. In the event of a first relapse, the preferred option is treatment with immunochemotherapy i.e. a combination of cladribine plus rituximab. Subsequent relapses are treated with moxetumomab pasudotox or BRAF inhibitors which provide indisputable benefits if third-line treatment is required. We will discuss in patients with relapsed/refractory hairy cell leukemia the needs for personalized medicine and the advantages and disadvantages of each treatment modality. The good prognosis for LT requires treatments that are not immunosuppressive, non-myelotoxic, and do not increase the risk of secondary cancers.

Vemurafenib plus Rituximab in Refractory or Relapsed Hairy-Cell Leukemia

BACKGROUND

Hairy-cell leukemia (HCL) is a CD20+ indolent B-cell cancer in which a BRAF V600E kinase-activating mutation plays a pathogenetic role. In clinical trials involving patients with refractory or relapsed HCL, the targeting of BRAF V600E with the oral BRAF inhibitor vemurafenib led to a response in 91% of the patients; 35% of the patients had a complete response. However, the median relapse-free survival was only 9 months after treatment was stopped.

METHODS

In a phase 2, single-center, academic trial involving patients with refractory or relapsed HCL, we assessed the safety and efficacy of vemurafenib (960 mg, administered twice daily for 8 weeks) plus concurrent and sequential rituximab (375 mg per square meter of body-surface area, administered for 8 doses over a period of 18 weeks). The primary end point was a complete response at the end of planned treatment.

RESULTS

Among the 30 enrolled patients with HCL, the median number of previous therapies was 3. A complete response was observed in 26 patients (87%) in the intention-to-treat population. All the patients who had HCL that had been refractory to chemotherapy (10 patients) or rituximab (5) and all those who had previously been treated with BRAF inhibitors (7) had a complete response. Thrombocytopenia resolved after a median of 2 weeks, and neutropenia after a median of 4 weeks. Of the 26 patients with a complete response, 17 (65%) were cleared of minimal residual disease (MRD). Progression-free survival among all 30 patients was 78% at a median follow-up of 37 months; relapse-free survival among the 26 patients with a response was 85% at a median follow-up of 34 months. In post hoc analyses, MRD negativity and no previous BRAF inhibitor treatment correlated with longer relapse-free survival. Toxic effects, mostly of grade 1 or 2, were those that had previously been noted for these agents.

CONCLUSIONS

In this small study, a short, chemotherapy-free, nonmyelotoxic regimen of vemurafenib plus rituximab was associated with a durable complete response in most patients with refractory or relapsed HCL. (Funded by the European Research Council and others; HCL-PG03 EudraCT number, 2014-003046-27.).

MAP-Kinase-Driven Hematopoietic Neoplasms: A Decade of Progress in the Molecular Age

Mutations in members of the mitogen-activated protein kinase (MAPK) pathway are extensively studied in epithelial malignancies, with BRAF mutations being one of the most common alterations activating this pathway. However, BRAF mutations are overall quite rare in hematological malignancies. Studies over the past decade have identified high-frequency BRAF V600E, MAP2K1, and other kinase alterations in two groups of MAPK-driven hematopoietic neoplasms: hairy cell leukemia (HCL) and the systemic histiocytoses. Despite HCL and histiocytoses sharing common molecular alterations, these are phenotypically distinct malignancies that differ in respect to clinical presentation and suspected cell of origin. The purpose of this review is to highlight the molecular advancements over the last decade in the histiocytic neoplasms and HCL and discuss the impact these insights have had on our understanding of the molecular pathophysiology, cellular origins, and therapy of these enigmatic diseases as well as perspectives for future research directions.

Current and Emerging Therapeutic Options for Hairy Cell Leukemia Variant

Hairy cell leukemia variant (HCL-v) is a rare B-cell lymphoproliferative disorder with distinct immunophenotypic and molecular characteristics when compared to classical hairy cell leukemia (HCL-c). In contrast to the enormous progress in therapeutic options for HCL-c, HCL-v remains a therapeutic challenge due to inferior outcomes with standard chemoimmunotherapy and BCR signaling pathway inhibitors, and due to the fact that HCL-v has limited molecular therapeutic targets. In addition, because of the rarity of the disease, there is a paucity of later phase studies or multicenter trials to guide treatment decisions. In this article, we briefly review the diagnostic criteria and clinical characteristics of HCL-v and present a comprehensive overview of current therapeutic options in HCL-v.

New developments in non-Hodgkin lymphoid malignancies

The revised fourth edition of the World Health Organization (WHO) Classification of Tumours of Haematopoietic and Lymphoid Tissues (2017) reflects significant advances in understanding the biology, genetic basis and behaviour of haematopoietic neoplasms. This review focuses on some of the major changes in B-cell and T-cell non-Hodgkin lymphomas in the 2017 WHO and includes more recent updates. The 2017 WHO saw a shift towards conservatism in the classification of precursor lesions of small B-cell lymphomas such as monoclonal B-cell lymphocytosis, in situ follicular and in situ mantle cell neoplasms. With more widespread use of next generation sequencing (NGS), special entities within follicular lymphoma and mantle cell lymphoma were recognised with recurrent genetic aberrations and unique clinicopathological features. The diagnostic workup of lymphoplasmacytic lymphoma and hairy cell leukaemia has been refined with the discovery of MYD88 L265P and BRAF V600E mutations, respectively, in these entities. Recommendations in the immunohistochemical evaluation of diffuse large B-cell lymphoma include determining cell of origin and expression of MYC and BCL2, so called 'double-expressor' phenotype. EBV-positive large B-cell lymphoma of the elderly has been renamed to recognise its occurrence amongst a wider age group. EBV-positive mucocutaneous ulcer is a newly recognised entity with indolent clinical behaviour that occurs in the setting of immunosuppression. Two lymphomas with recurrent genetic aberrations are newly included provisional entities: Burkitt-like lymphoma with 11q aberration and large B-cell lymphoma with IRF4 rearrangement. Aggressive B-cell lymphomas with MYC, BCL2 and/or BCL6 rearrangements, so called 'double-hit/triple-hit' lymphomas are now a distinct entity. Much progress has been made in understanding intestinal T-cell lymphomas. Enteropathy-associated T-cell lymphoma, type II, is now known to not be associated with coeliac disease and is hence renamed monomorphic epitheliotropic T-cell lymphoma. An indolent clonal T-cell lymphoproliferative disorder of the GI tract is a newly included provisional entity. Angioimmunoblastic T-cell lymphoma and nodal T-cell lymphomas with T-follicular helper phenotype are included in a single broad category, emphasising their shared genetic and phenotypic features. Anaplastic large cell lymphoma, ALK- is upgraded to a definitive entity with subsets carrying recurrent rearrangements in DUSP22 or TP63. Breast implant-associated anaplastic large cell lymphoma is a new provisional entity with indolent behaviour. Finally, cutaneous T-cell proliferations include a new provisional entity, primary cutaneous acral CD8-positive T-cell lymphoma, and reclassification of primary small/medium CD4-positive T-cell lymphoma as lymphoproliferative disorder.

Moxetumomab pasudotox in heavily pre-treated patients with relapsed/refractory hairy cell leukemia (HCL): long-term follow-up from the pivotal trial

Background

Moxetumomab pasudotox is a recombinant CD22-targeting immunotoxin. Here, we present the long-term follow-up analysis of the pivotal, multicenter, open-label trial (NCT01829711) of moxetumomab pasudotox in patients with relapsed/refractory (R/R) hairy cell leukemia (HCL).

Methods

Eligible patients had received ≥ 2 prior systemic therapies, including ≥ 2 purine nucleoside analogs (PNAs), or ≥ 1 PNA followed by rituximab or a BRAF inhibitor. Patients received 40 µg/kg moxetumomab pasudotox intravenously on Days 1, 3, and 5 of each 28-day cycle for up to six cycles. Disease response and minimal residual disease (MRD) status were determined by blinded independent central review. The primary endpoint was durable complete response (CR), defined as achieving CR with hematologic remission (HR, blood counts for CR) lasting > 180 days.

Results

Eighty adult patients were treated with moxetumomab pasudotox and 63% completed six cycles. Patients had received a median of three lines of prior systemic therapy; 49% were PNA-refractory, and 38% were unfit for PNA retreatment. At a median follow-up of 24.6 months, the durable CR rate (CR with HR > 180 days) was 36% (29 patients; 95% confidence interval: 26–48%); CR with HR ≥ 360 days was 33%, and overall CR was 41%. Twenty-seven complete responders (82%) were MRD-negative (34% of all patients). CR lasting ≥ 60 months was 61%, and the median progression-free survival without the loss of HR was 71.7 months. Hemolytic uremic and capillary leak syndromes were each reported in ≤ 10% of patients, and ≤ 5% had grade 3–4 events; these events were generally reversible. No treatment-related deaths were reported.

Conclusions

Moxetumomab pasudotox resulted in a high rate of durable responses and MRD negativity in heavily pre-treated patients with HCL, with a manageable safety profile. Thus, it represents a new and viable treatment option for patients with R/R HCL, who currently lack adequate therapy.

Trial registration

ClinicalTrials.gov identifier: NCT01829711; first submitted: April 9, 2013. https://clinicaltrials.gov/ct2/show/NCT01829711

Supplementary information

Supplementary information accompanies this paper at 10.1186/s13045-020-01004-y.

Long-term follow-up after rituximab plus bendamustine in a patient with relapsed or refractory hairy cell leukemia variant: A case report

INTRODUCTION

Hairy cell leukemia variant (HCL-v) is a rare lymphoproliferative disorder regarded as a splenic B-cell lymphoma/leukemia, unclassifiable tumor in the 2017 World Health Organization classification of lymphoid tumors. The prognosis of HCL-v is much worse than that of classical hairy cell leukemia and there is no consensus regarding the optimal treatment strategy for HCL-v. For patients with indolent lymphoma, rituximab plus bendamustine (RB) has proven effective in several clinical trials. Thus, RB is expected to be a treatment option for patients with HCL-v, but there have been few reports of its use in these patients.

PATIENT CONCERNS

A 64-year-old man presented with leukocytosis and abnormal lymphocytes in peripheral blood in a medical examination. Computed tomography revealed mild splenomegaly, but no lymph node enlargement.

DIAGNOSIS

The patient was initially diagnosed with low-grade B-cell lymphoma. After he experienced a second relapse, his clinical data were reviewed again; subsequently, he was diagnosed with HCL-v on the basis of clinical presentation, flow cytometry findings, and cytogenetic abnormalities.

INTERVENTIONS

The patient was first treated with the cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) regimen. After the regimen was ineffective, he received six cycles of RB. After relapse, the patients received an additional six cycles of RB.

OUTCOMES

The patients exhibited a slight reduction of the abnormal lymphocyte level but insufficient therapeutic efficacy during CHOP therapy. After the first cycle of RB, the patient exhibited an immediate response with the absence of minimal residual disease. He remained relapse-free for approximately 67 months. After a second relapse, complete response was again achieved with the absence of minimal residual disease following RB re-administration. He remained relapse-free for approximately 29 months after the second RB.

CONCLUSION

RB could be a treatment option for patients with relapsed or refractory HCL-v. Further research is needed to establish the optimal treatment regimen for patients of HCL-v.

Massive splenomegaly in hairy cell leukemia causing urinary retention

Hairy cell leukemia can cause massive splenomegaly which may lead to urinary retention and constipation. Patients usually require a splenectomy for relief of symptoms.

Massive Splenomegaly and Pancytopenia: It's a Hairy Situation

A 33-year-old previously healthy Middle Eastern male presented to the emergency department with four weeks of progressively worsening fatigue, dyspnea on exertion, night sweats, and a 10-pound weight loss after suffering a self-limiting viral upper respiratory illness. He was found to be profoundly anemic and thrombocytopenic with normal white blood cell count with a lymphocytic predominance. His anemia was refractory to red blood cell transfusions, to which he developed hyperbilirubinemia. A CT scan revealed hepatomegaly and massive splenomegaly associated with multi-station abdominopelvic lymphadenopathy. A peripheral blood smear revealed several lymphocytes with hairy cell features and bone marrow biopsy revealed hypercellularity with interstitial infiltration by mature lymphoid cells. Flow cytometry confirmed the diagnosis of hairy cell leukemia (HCL) and this patient was initiated on cladribine chemotherapy. This case illustrates the uniqueness of this patient presenting within a short time course, at an atypical age, and with uncommon features for HCL including lymphadenopathy, hepatomegaly, and petechial skin rash. This case also highlights an important point regarding the management of severe anemia in the acute setting while undergoing splenic sequestration. His lack of response to red blood cell transfusions highlights the need for more research on the use of transfusions in patients who are not current surgical candidates for splenectomy.

Clonal dynamics in a composite chronic lymphocytic leukemia and hairy cell leukemia-variant

Composite lymphoma is the rare simultaneous manifestation of two distinct lymphomas. Chronic lymphocytic leukemia (CLL) has a propensity for occurring in composite lymphomas, a phenomenon that remains to be elucidated. We applied cytogenetics, droplet digital polymerase chain reaction, and massively parallel sequencing to analyze longitudinally a patient with CLL, who 3 years later showed transformation to a hairy cell leukemia-variant (HCL-V). Outgrowth of the IGHV4-34-positive HCL-V clone at the expense of the initially dominant CLL clone with trisomy 12 and MED12 mutation started before CLL-guided treatment and was accompanied by a TP53 mutation, which was already detectable at diagnosis of CLL. Furthermore, deep sequencing of IGH showed a composite lymphoma with presence of both disease components at all analyzed timepoints (down to a minor clone: major clone ratio of ~1:1000). Overall, our analyses showed a disease course that resembled clonal dynamics reported for malignancies with intratumoral heterogeneity and illustrate the utility of deep sequencing of IGH to detect distinct clonal populations at diagnosis, monitor clonal response to therapy, and possibly improve clinical outcomes.

A Rare Case of Hairy Cell Leukemia with Unusual Loss of CD123 Associated with COVID-19 at the Time of Presentation

Coronavirus disease 2019 (COVID-19) pandemic has been a serious threat and has been reported with different presentations and complications. Older age, along with comorbidities such as diabetes, hypertension, or cardiac disease, increases the risk factors for COVID-19 severity and death [N Engl J Med. 2020;382(18):1708–20 and Lancet Respir Med. 2020 05;8(5):475–81]. It is proposed that cancer patients have a significantly higher incidence of severe incidents including admission to the intensive care unit, the necessity for assisted ventilation, and even death after catching the virus compared with non-cancer patients [Lancet Oncol. 2020;21(3):335–7]. It is also described that cancer patients appear to be twice as likely to contract infection with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) [JAMA Oncol. 2020;6(7):1108–10]. Hairy cell leukemia (HCL) is a rare B-cell lymphoproliferative disorder, with patients typically presenting with cytopenias, marked splenomegaly in 80–90% of patients, circulating leukemia cells, bone marrow infiltration and the presence of BRAF V600E somatic mutation [Indian J Hematol Blood Transfus. 2014;30(Suppl 1):413–7]. Leukemic cells classically have central nuclei and abundant cytoplasm with hairy-like projections and express CD11c, CD25, CD103, and CD123 [Indian J Hematol Blood Transfus. 2014;30(Suppl 1):413–7]. Loss of CD123 in HCL has been rarely reported in the literature [Am J Hematol. 2019;94(12):1413–22]. We describe a unique case of a COVID-19-positive male who presented with severe respiratory symptoms, deteriorated quickly, and was intubated. Workup of severe progressive pancytopenia and bone marrow examination revealed HCL without splenomegaly and with atypical unusual loss of CD123. To our knowledge, this is the first case of CD123-negative HCL without splenomegaly associated with COVID-19 infection as the initial presentation.

IL2RA Promotes Aggressiveness and Stem Cell-Related Properties of Acute Myeloid Leukemia

Overexpression of IL2RA, which encodes the alpha chain of the IL2 receptor, is associated with chemotherapy resistance and poor outcome in acute myeloid leukemia (AML). The clinical potential of anti-IL2RA therapy is, therefore, being explored in early-stage clinical trials. Notwithstanding, only very limited information regarding the biological function of IL2RA in AML is available. Using genetic manipulation of IL2RA expression as well as antibody-mediated inhibition of IL2RA in human cell lines, mouse models, and primary patient samples, we investigated the effects of IL2RA on AML cell proliferation and apoptosis, and on pertinent signaling pathways. The impact of IL2RA on the properties of leukemic stem cells (LSC) and on leukemogenesis were queried. IL2RA promoted proliferation and cell-cycle activity and inhibited apoptosis in human AML cell lines and primary cells. These phenotypes were accompanied by corresponding alterations in cell-cycle machinery and in pathways associated with cell survival and apoptosis. The biological roles of IL2RA were confirmed in two genetically distinct AML mouse models, revealing that IL2RA inhibits differentiation, promotes stem cell-related properties, and is required for leukemogenesis. IL2RA antibodies inhibited leukemic, but not normal, hematopoietic cells and synergized with other antileukemic agents in this regard. Collectively, these data show for the first time that IL2RA plays key biological roles in AML and underscore its value as a potential therapeutic target in this disease. SIGNIFICANCE: This study identifies IL2RA as a potential therapeutic target in AML, where it is shown to regulate proliferation, differentiation, apoptosis, stem cell-related properties, and leukemogenesis.

Bone lesions in hairy cell leukemia: Diagnosis and treatment

Skeletal involvement is a rare complication of hairy cell leukemia (HCL) with an incidence of approximately 3%. Bone lesions are commonly lytic, and the most common sites of involvement are the femoral head and neck. Skeletal involvement is typically associated with high tumor burden and bone marrow infiltration. However, isolated cases of skeletal disease without splenomegaly or bone marrow involvement are occasionally reported. This review focuses on skeletal lesions in HCL, particularly the pathogenesis, clinical symptoms, diagnostic methods, and treatment approach. A literature review of the MEDLINE database for articles in English concerning hairy cell leukemia, skeletal symptoms, bone involvement was conducted via PubMed. Publications from January 1970 to May 2020 were scrutinized. Additional relevant publications were obtained by reviewing the references from the chosen articles.

Concurrent chronic lymphocytic leukemia/small lymphocytic lymphoma and hairy cell leukemia: clinical, pathologic and molecular features

Simultaneous occurrence of hairy cell leukemia (HCL) and chronic lymphocytic leukemia/small lymphocytic lymphoma (termed CLL) is very rare. Clinical characteristics, pathology and management of these cases have not been well described. We present six patients with CLL and HCL or HCL variant (HCL-v). Of six patients, three were initially diagnosed with CLL and later developed concurrent HCL. Two patients had concurrent HCL or HCL-v and CLL at initial diagnosis. One had HCL first, followed by concurrent CLL. Polymerase chain reaction analysis demonstrated B-cell clonality in all cases, with two distinct clonal populations in four cases, and three clonal populations in one case. Five patients were treated with a combination of a purine analog such as fludarabine, cladribine, and pentostastin with either rituximab or ibrutinib, while one received dabrefenib and trametinib. All patients achieved a durable response to either CLL or HCL-directed therapy with reduction or ablation of coexisting B-cell clones.