Large granular lymphocytic leukemia - A retrospective study of 319 cases

Clinical features and prognosis of chronic natural killer cell lymphoproliferative disorders

OBJECTIVE

To analyze the current treatment status and prognostic regression of the chronic NK cell lymphoproliferative disorder (CLPD-NK).

METHODS

We retrospectively analyzed the clinical features, treatment and prognosis of 18 patients with CLPD-NK who were treated at our Hospital between September 2016 and September 2022.

RESULTS

Eighteen patients were included: three patients were treated with chemotherapy, five patients underwent immune-related therapy, one patient was treated with glucocorticoids alone, five patients were administered granulocyte colony-stimulating factor, blood transfusion therapy, or anti-infection therapy, followed by observation and follow-up, and four patients were observed without treatment. Fifteen patients survived, including two patients who achieved complete remission (CR) and seven patients who achieved partial remission (PR), of whom one patient progressed to Aggressive NK-cell leukemia (ANKL) and sustained remission after multiple lines of treatment; three patients were not reviewed, of which one patient was still in active disease, three patients developed hemophagocytic syndrome during treatment and eventually died, one of them had positive Epstein-Barr virus (EBV) expression. The 5-years overall survival rate was 83%.

CONCLUSION

Most patients with CLPD-NK have inert progression and a good prognosis, whereas some patients have a poor prognosis after progressing to ANKL and combined with hemophagocytic syndrome. Abnormal NK cells invading the center suggest a high possibility of ANKL development, and immunosuppressants and hormones are effective treatments for this disease.

Characteristics of large granular lymphocyte leukemia associated with variable common immunodeficiency disorders: A study of 12 cases

OBJECTIVES

Common Variable Immunodeficiency Disorders (CVID) and Large Granular Lymphocytes leukemia (LGLL) exhibit diverse clinical manifestations including infections, dysimmunity, and lymphoproliferation. Recent decades have seen the discovery of new genes in the lymphopoiesis pathway, such as JAK-STAT. This case series supplemented by a literature review aims to describe clinical and biological characteristics of patients with both CIVD and LGLL.

METHODOLOGY

Patients were included through a call for comments to French and Belgian centers and through a literature review via PubMed. Clinical characteristics were compared to two large French cohort involving CVID and LGLL patients.

RESULTS

Twelve patients were included. In all cases, CVID precedes LLGL (median diagnosis delay for LLGL was 7 years). Most cases presented with splenomegaly and autoimmune cytopenia. Ten out of 12 patients underwent splenectomy during follow up.

CONCLUSIONS

Patients with LGLL and CVID differ from patients without immune deficiency in term of clinical presentation and prognosis. We suggest CVID may act as a trigger of LGL lymphocytosis, due to endogenous and exogenous antigenic pressure leading to the selection of a dominant LGL clone and stimulation of the JAK-STAT pathway. The role of splenomegaly and splenectomy in LGLL onset warrant further investigation in future studies.

T-cell Large Granular Lymphocytic Leukemia with a STAT3 mutation successfully treated with Cord Blood Transplantation

A 64-year-old woman presented with agranulocytosis, anemia, and bacteremia, leading to a diagnosis of T-cell large granular lymphocytic leukemia (T-LGLL). A molecular analysis identified a signal transducer and activator of transcription 3 (STAT3) Y640F variant. Initial treatment with cyclophosphamide and prednisolone did not improve her condition, but serious infections were observed. The patient underwent cord blood transplantation (CBT) after preconditioning with fludarabine, busulfan, and total body irradiation, yielding a STAT3 Y640F variant disappearance, based on allele-specific quantitative polymerase chain reaction (AS-qPCR). In this case, CBT is a promising refractory T-LGLL treatment option, and the STAT3 Y640F variant AS-qPCR is a T-LGLL activity marker.

T-cell large granular lymphocytic leukemia with a STAT3 mutation successfully treated with cord blood transplantation

A 64-year-old woman presented with agranulocytosis, anemia, and bacteremia, leading to a diagnosis of T-cell large granular lymphocytic leukemia (T-LGLL). A molecular analysis identified a signal transducer and activator of transcription 3 (STAT3) Y640F variant. Initial treatment with cyclophosphamide and prednisolone did not improve her condition, but serious infections were observed. The patient underwent cord blood transplantation (CBT) after preconditioning with fludarabine, busulfan, and total body irradiation, yielding a STAT3 Y640F variant disappearance, based on allele-specific quantitative polymerase chain reaction (AS-qPCR). In this case, CBT is a promising refractory T-LGLL treatment option, and the STAT3 Y640F variant AS-qPCR is a T-LGLL activity marker.

Aleukemic variant of T-cell large granular lymphocyte leukemia in patients with rheumatoid arthritis - diagnostically challenging subtype

INTRODUCTION

The typical clinical manifestations of T-cell large granular lymphocyte (T-LGL) leukemia are an increase in the number of large granular lymphocytes (LGLs) in the blood > 2000 cells/μL, neutropenia, and splenomegaly. In rare cases of so-called 'aleukemic' T-LGL leukemia, the number of LGLs is <400-500 cells/μL. In patients with rheumatoid arthritis (RA), distinguishing T-LGL leukemia with low tumor burden in the blood and bone marrow from Felty syndrome (FS) poses diagnostic challenges.

AREAS COVERED

This review aimed to describe the basic characteristics and variants of aleukemic T-LGL leukemia, with a special focus on aleukemic T-LGL leukemia with massive splenomegaly (splenic variant of T-LGL leukemia) and differential diagnosis of such cases with hepatosplenic T-cell lymphoma. The significance of mutations in the signal transducer and activator of transcription 3 (STAT3) gene for distinguishing aleukemic RA-associated T-LGL leukemia from FS is discussed, along with the evolution of the T-LGL leukemia diagnostic criteria. PubMed database was used to search for the most relevant literature.

EXPERT OPINION

Evaluation of STAT3 mutations in the blood and bone marrow using next-generation sequencing, as well as a comprehensive spleen study, may be necessary to establish a diagnosis of aleukemic RA-associated T-LGL leukemia.

Clinical characteristics and treatment outcomes of Asian patients with T-cell large granular lymphocytic Leukemia: a single-center analysis of 67 cases

Large granular lymphocytic (LGL) leukemia is a clonal lymphoproliferative disorder of LGLs derived from cytotoxic T lymphocytes or natural killer cells. However, the clinical features and treatment responses are still not fully understood because of the rarity of the disease. To describe and assess a cohort of patients with T-cell large granular lymphocytic leukemia (T-LGLL). Single-center, retrospective, observational study. We retrospectively collected the clinical data of patients diagnosed with T-LGLL at Seoul National University Hospital since 2006. We included 67 patients in this study. The median age at diagnosis was 60 years. Additionally, 37 patients (55%) were symptomatic, and 25 (37%) had splenomegaly; 54 patients (81%) required treatment. Cyclophosphamide (n = 35), methotrexate (n = 25), and cyclosporin A (n = 19) were used most frequently for treatment, and their overall response rates were similar: cyclophosphamide (77%), methotrexate (64%), and cyclosporin A (63%). Splenomegaly was associated with an increased response rate to first-line therapy and a decreased complete response rate. Thrombocytopenia was associated with decreased response rates to cyclophosphamide, methotrexate, cyclosporin A, and steroids. In contrast, a high LGL number (> 2000/µL) in the peripheral blood smear was associated with increased response rates to cyclophosphamide, methotrexate, cyclosporin A, and steroids. This study describes the clinical features and treatment outcomes of patients with T-LGLL, providing valuable information for clinical decision-making regarding T-LGLL treatment.

Large Granular Lymphocytic Leukemia: Clinical Features, Molecular Pathogenesis, Diagnosis and Treatment

Large granular lymphocytic (LGL) leukemia is a lymphoproliferative disorder characterized by persistent clonal expansion of mature T- or natural killer cells in the blood via chronic antigenic stimulation. LGL leukemia is associated with specific immunophenotypic and molecular features, particularly STAT3 and STAT5 mutations and activation of the JAK-STAT3, Fas/Fas-L and NF-κB signaling pathways. Disease-related deaths are mainly due to recurrent infections linked to severe neutropenia. The current treatment is based on immunosuppressive therapies, which frequently produce unsatisfactory long-term responses, and for this reason, personalized approaches and targeted therapies are needed. Here, we discuss molecular pathogenesis, clinical presentation, associated autoimmune disorders, and the available treatment options, including emerging therapies.

The complex relationship between large granular lymphocyte leukemia and rheumatic disease

INTRODUCTION

Large granular lymphocytic (LGL) leukemia is a rare lymphoproliferative disorder characterized by an expansion of clonal T or NK lymphocytes. Neutropenia-related infections represent the main clinical manifestation. Even if the disease follows an indolent course, most patients will ultimately need treatment in their lifetime. Interestingly, LGL leukemia is characterized by a high frequency of autoimmune disorders with rheumatoid arthritis being the most frequent.

AREAS COVERED

This review covers the pathophysiology, clinic-biological features and the advances made in the treatment of LGL leukemia. A special focus will be made on the similarities in the pathophysiology of LGL leukemia and the frequently associated rheumatic disorders.

EXPERT OPINION

Recent advances in the phenotypic and molecular characterization of LGL clones have uncovered the key role of JAK-STAT signaling in the pathophysiology linking leukemic cells expansion and autoimmunity. The description of the molecular landscape of T- and NK-LGL leukemia and the improved understanding of the associated rheumatic disorders open the way to the development of new targeted therapies effective on both conditions.

Peripheral neuropathy associated with chronic lymphoproliferative disorders of natural killer cells (CLPD-NK): a case report and literature review

BACKGROUND

Chronic lymphoproliferative disorders of natural killer cells (CLPD-NK) is a rare lymphoproliferative disease. Peripheral neuropathy is an unusual symptom of CLPD-NK. We report a case of peripheral neuropathy associated with CLPD-NK and perform a review of literatures.

CASE PRESENTATION

a 62-year-old woman presented with progressive numbness and weakness in both extremities. Electrophysiological examinations indicated a sensorimotor polyneuropathy. Peripheral blood examination revealed that the number of white blood cells (WBC) and lymphocytes were significantly increased. Flow cytometry analysis identified that 84% of the lymphocytes are NK cells that mainly expressed CD56, combined with variable expression of CD16, CD2, CD7, CD94, granzyme B, perforin, and CD158 but negative for CD3. Sural nerve biopsy revealed that a plethora of NK cells infiltrated into nerve fascicles. On treatment with combined cyclophosphamide and corticosteroids, her symptoms rapidly improved. Moreover, the absolute lymphocyte count and its proportion recovered to normal range after 3 months' treatment.

CONCLUSION

To the best of our knowledge, this is the first case report of peripheral neuropathy associated with CLPD-NK from Chinese. This rare lymphoproliferative disease should be considered if peripheral neuropathy combines with increased WBC or lymphocytes. Immunosuppressive drugs are the major treatment and most patients can achieve a good prognosis.

Large granular lymphocyte leukemia: An indolent clonal proliferative disease associated with an array of various immunologic disorders

Large granular lymphocyte leukemia (LGLL) is a chronic lymphoproliferative disorder characterized by the proliferation of T or NK cytotoxic cells in the peripheral blood, the spleen and the bone marrow. Neutropenia leading to recurrent infections represents the main manifestation of LGLL. One specificity of LGLL is its frequent association with auto-immune disorders, among them first and foremost rheumatoid arthritis, and other hematologic diseases, including pure red cell aplasia and bone marrow failure. The large spectrum of manifestations and the classical indolent course contribute to the diagnosis difficulties and the frequency of underdiagnosed cases. Of importance, the dysimmune manifestations disappear with the treatment of LGLL as the blood cell counts normalize, giving a strong argument for a pathological link between the two entities. The therapeutic challenge results from the high rate of relapses following the first line of immunosuppressive drugs. New targeted agents, some of which are currently approved in autoimmune diseases, appear to be relevant therapeutic strategies to treat LGLL, by targeting key activated pathways involved in the pathogenesis of the disease, including JAK-STAT signaling.

T-cell clonality testing for the diagnosis of T-cell large granular lymphocytic leukemia: Are we identifying pathology or incidental clones?

INTRODUCTION

T-cell clonality testing by T-cell receptor (TCR) gene rearrangement is key to the diagnosis of T-cell lymphoproliferative disorders such as T-cell large granular lymphocytic (T-LGL) leukemia. Benign clonal T-cell expansions, however, are commonly found in patients without identifiable disease, a condition referred to as T-cell clones of uncertain significance (T-CUS). In practice, T-cell clonality testing is performed for a range of reasons and results are often challenging to interpret given the overlap between benign and malignant clonal T-cell proliferations and uncertainties in the management of T-CUS.

METHODS

We conducted a 5-year retrospective cohort study of 211 consecutive patients who underwent PCR-based T-cell clonality testing for suspected T-LGL leukemia at our institution to characterize the use of T-cell clonality testing and its impact on patient management.

RESULTS

Overall, 46.4% (n = 98) of individuals tested had a clonal T-cell population identified. Patients with a monoclonal T-cell population were more likely to be older, have rheumatoid arthritis and have higher lymphocyte counts compared to patients with polyclonal populations. The majority of patients eventually diagnosed and treated for T-LGL leukemia had rheumatoid arthritis and lower neutrophil counts compared to untreated patients with monoclonal T-cell populations. A diagnosis of T-LGL leukemia was made in only a minority of patients (n = 48, 22.7%), and only a small proportion were treated (n = 17, 8.1%).

CONCLUSION

Our study suggests that T-cell clonality testing most commonly identifies incidental T-cell clones with only a minority of patients receiving a diagnosis of T-LGL leukemia and fewer requiring active treatment. These finding indicate an opportunity to improve utilization of T-cell clonality testing in clinical practice to better target patients where the results of testing would impact clinical management.

Molecular Features and Diagnostic Challenges in Alpha/Beta T-Cell Large Granular Lymphocyte Leukemia

Large granular lymphocyte leukemia is a rare chronic lymphoproliferative disease of cytotoxic lymphocytes. The diagnosis, according to the WHO, is based on a persistent (>6 months) increase in the number of LGL cells in the peripheral blood without an identifiable cause. A further distinction is made between T-LGL and NK-LGL leukemia. The molecular sign of LGL leukemia is the mutation of STAT3 and other genes associated with the JAK/STAT pathway. The most common clinical features are neutropenia, anemia, and thrombocytopenia, and it is often associated with various autoimmune conditions. It usually has an indolent course. Due to the rarity of the disease, no specific treatment has yet been identified. Immunosuppressive therapy is used and may allow for disease control and long-term survival, but not eradication of the leukemic clone. Here, we discuss the clinical presentation, diagnostic challenges, pathophysiology, and different treatment options available for alpha/beta T-LGL leukemia, which is the most common disease (85%), in order to better understand and manage this often misunderstood disease.

Clinical Study of the Relationship between Sjögren Syndrome and T-Cell Large Granular Lymphocytic Leukemia: Single-Center Experience

The relationship between Sjögren syndrome (SS) and T-cell large granular lymphocytic (T-LGL) leukemia remains unclear. In this paper, we report for the first time a large case series of 21 patients with primary and secondary SS associated with T-LGL leukemia. Our results suggest the importance of considering T-LGL leukemia in the diagnostic evaluation of SS patients, particularly when neutropenia occurs. We also postulate that elevated antinuclear antibody titers in patients with T-LGL leukemia indicate the need for the clinical assessment of SS. To assess whether SS affects the frequency of the signal transducer and activator of transcription 3 (STAT3) gene mutations in T-LGL leukemia, we examined STAT3 mutations by next-generation sequencing in two cohorts of patients: with SS-associated T-LGL leukemia and T-LGL leukemia in the setting of rheumatic diseases but without SS. While our results suggest that SS, per se, is not associated with an increased frequency of STAT3 mutations in T-LGL leukemia, further studies are needed to better assess the role of the STAT pathway in the development of concomitant SS and T-LGL leukemia.

LGL Clonal Expansion and Unexplained Cytopenia: Two Clues Don't Make an Evidence

Clonal expansions of large granular lymphocytes (LGL) have been reported in a wide spectrum of conditions, with LGL leukemia (LGLL) being the most extreme. However, the boundaries between LGLL and LGL clones are often subtle, and both conditions can be detected in several clinical scenarios, particularly in patients with cytopenias. The intricate overlap of LGL clonal expansion with other disease entities characterized by unexplained cytopenias makes their classification challenging. Indeed, precisely assigning whether cytopenias might be related to inadequate hematopoiesis (i.e., LGL as a marginal finding) rather than immune-mediated mechanisms (i.e., LGLL) is far from being an easy task. As LGL clones acquire different pathogenetic roles and relevance according to their diverse clinical settings, their detection in the landscape of bone marrow failures and myeloid neoplasms has recently raised growing clinical interest. In this regard, the current availability of different diagnostic techniques, including next generation sequencing, shed light on the relationship between LGL clones and cytopenias, paving the way towards a better disease classification for precision medicine treatments. Herein, we discuss the clinical relevance of LGL clones in the diagnostic algorithm to be followed in patients presenting with cytopenias, offering a foundation for rational management approaches.

STAT3 mutations in “gray-zone” cases of T-cell large granular lymphocytic leukemia associated with autoimmune rheumatic diseases

A persistently increased T-cell large granular lymphocyte (T-LGL) count in the blood of more than 2 × 10⁹/L for at least 6 months is necessary for a reliable diagnosis of T-LGL leukemia. In cases with LGL counts of approximately 0.5–2 × 10⁹/L, a diagnosis of T-LGL leukemia can be made if clonal rearrangement of T-cell receptor (TCR) genes is present and if the patient shows typical manifestations of T-LGL leukemia, such as cytopenia, splenomegaly, or concomitant autoimmune disease. However, in cases with LGL counts of less than 0.5 × 10⁹/L, the diagnosis of T-LGL leukemia is questionable (termed as “gray-zone” cases). Although mutations in signal transducer and activator of transcription 3 (STAT3) gene are the molecular hallmark of T-LGL leukemia, their diagnostic value in the “gray-zone” cases of T-LGL leukemia has not been evaluated – our study has been aimed to examine the prevalence of STAT3 mutations in these cases. Herein, we describe 25 patients with autoimmune rheumatic diseases, neutropenia, clonal rearrangement of TCR genes, and circulating LGL count of less than 0.5 × 10⁹/L. Splenomegaly was observed in 19 (76%) patients. Mutations in the STAT3 were detected in 56% of patients using next-generation sequencing. Importantly, in 3 patients, no involvement of the blood and bone marrow by malignant LGLs was noted, but examination of splenic tissue revealed infiltration by clonal cytotoxic T-lymphocytes within the red pulp, with greater prominence in the cords. We suggest using the term “splenic variant of T-LGL leukemia” for such cases.

Allogeneic Bone Marrow Transplant as a Cure for Refractory T-Cell Large Granular Lymphocytic Leukemia in an Adolescent

T-cell large granular lymphocytic (T-LGL) leukemia is a rare, typically indolent neoplasm with a median age of onset above 60 years. Pathogenesis involves clonal T-cell expansion, and nearly all reported pediatric cases have been associated with concurrent autoimmune disease. Immunosuppressive therapy often mitigates sequelae, but definitive cure is not routinely achieved. Here we present an otherwise healthy 13-year-old with T-LGL leukemia refractory to all standard treatments. Our patient ultimately underwent allogeneic bone marrow transplant (BMT) and is now stable in remission 3 years post-BMT. BMT may offer a viable definitive cure for refractory T-LGL leukemia in very young patients.

Pathogenesis and Treatment of T-Large Granular Lymphocytic Leukemia (T-LGLL) in the Setting of Rheumatic Disease

A complex relationship exists between rheumatic diseases and cancer. This delicate balance between chronic inflammation and malignant cell transformation in hematologic neoplasms has been observed, but is not well defined. Large Granular Lymphocyte (LGL) leukemia is at the intersection of a clonal lymphoproliferative disease, chronic inflammation, and autoimmunity. The association between rheumatoid arthritis (RA) and the spectrum of Felty’s Syndrome is well-known. Other rheumatic disorders have been reported including systemic lupus erythematosus (SLE), Sjogren’s Syndrome (SS), vasculitis, Behcet’s Disease (BD) and systemic sclerosis. The association between T-LGLL and rheumatic disease pathogenesis has been hypothesized, but has not yet been fully understood. Components of a shared pathogenesis includes chronic antigen stimulation, JAK-STAT pathway activation and overlap of various cytokines. We will summarize current knowledge on the molecular understanding between T-LGLL and rheumatic disease. There are many potential areas of research to help meet this need and lead to development of targeted therapeutic options.

Case Report: First Report of T-Cell Large Granular Lymphocytic Leukemia With NPL-DHX9 Gene Fusion Successfully Treated With Cladribine: Clinical Experience and Literature Review

Background

T-cell large granular lymphocytic leukemia (T-LGLL) is a rare lymphoproliferative disorder that starts in T cells and is usually indolent. Long-term use of immunosuppressants, combined with agranulocytosis, is a double-edged sword, as both can lead to serious infections, especially in patients with combined hematologic malignancies and immune defects.

Case Presentation

A 30-year-old female patient was admitted to the hospital because of agranulocytosis for five years, with chest tightness, fatigue, and fever for two days. Pathology and metagenomic next-generation sequencing (mNGS) detected Aspergillus. Although she received cyclosporine and methylprednisolone, the patient showed drug intolerance and progression with invasive pulmonary fungal infections. After a bone marrow aspiration biopsy and other related examinations, she was diagnosed with T-LGLL and invasive pulmonary aspergillosis (IPA). T-cell immunophenotype was CD45+CD3dim+CD5-CD4-CD8+CD7+CD57p+CD25-CD30-, TCRγδ+, transducer and activator of transcripton-3 (STAT3) Y640F mutation and fusion gene NPL-DHX9 rearrangement were confirmed, which has never been reported in hematological diseases. After voriconazole regimen adjustment during treatment based on therapeutic drug concentration monitoring (TDM) and improvement in lung infection, the patient finally treated with purine nucleoside analogues (PNA) cladribine as a single agent at 0.14 mg/kg/d for 5 days. Complete response was achieved after four-cycles cladribine treatment (WBC 2.1*109/L, HGB 117 g/L, PLT 196*109/L, ANC 1.6*109/L, and ALC 0.2*109/L).

Conclusions

To our knowledge, this is the first case of T-LGLL with a rare γδ type and fusion gene NPL-DHX9 rearrangement. The patient was successfully treated with cladribine, suggesting that this regimen could be a promising therapeutic strategy for patients with aggressive T-LGLL.

Clinical characteristics and outcomes of 100 adult patients with pure red cell aplasia

Adult pure red cell aplasia (PRCA) is a rare syndrome characterized by a severe normocytic anemia, reticulocytopenia, and absence of erythroblasts from bone marrow. The standard treatment has not yet been established for PRCA, although cyclosporine (CsA), corticosteroids (CS) showed a response in PRCA. We retrospectively analyzed the clinical data of 60 primary and 40 secondary adult patients with acquired PRCA. The proportion of secondary PRCA is relatively high and commonly associated with large granular lymphocyte leukemia (LGLL) (28 cases, 70.0%). The remission-induced regimens included CS, CsA, or other agents, and the response rate was 66.7%, 71.4%, and 50%, respectively (P = 0.336). When treating with CsA, the response rate of LGLL-associated PRCA was lower than primary PRCA (42.1% vs 85.7%, P = 0.001). Logistic regression analysis showed that ORR was inversely related to LGLL-associated PRCA. LGLL-associated PRCA had poor therapeutic efficacy to CsA.

Persistent Large Granular Lymphocyte Clonal Expansions: “The Root of Many Evils”—And of Some Goodness

Simple Summary

Large granular lymphocyte leukemia (LGLL) is a chronic disorder of either mature T or NK lymphocytes. As clonal expansions of the immune system cells, difficulties in the distinction between a true neoplasia and a physiological reactive process have been common since its description. We review here the different conditions associated with persistent clonal LGL expansions and discuss their potential origin and whether they can modulate the clinical features.

Abstract

Large granular lymphocyte leukemia (LGLL) is a chronic disease of either mature phenotype cytotoxic CD3+ T lymphocytes or CD3- NK cells. LGLL diagnosis is hampered by the fact that reactive persistent clonal LGL expansions may fulfill the current criteria for LGLL diagnoses. In addition to the presence of characteristic clinical and hematological signs such as anemia or neutropenia, LGLL/LGL clonal expansions have been associated with an array of conditions/disorders. We review here the presence of these persistent clonal expansions in autoimmune, hematological disorders and solid neoplasms and after hematopoietic stem cell transplantation. These associations are a unique translational research framework to discern whether these persistently expanded LGL clones are causes or consequences of the concomitant clinical settings and, more importantly, when they should be targeted.

Large Granular Lymphocytic Leukemia: Current State of Diagnosis, Pathogenesis and Treatment

PURPOSE OF REVIEW

This manuscript aims at updating the knowledge on the clinico-biological characteristics, pathogenesis, and the diagnostic challenges of T-LGLL and CLPD-NK disorders and reviews the advances in the management and treatment of these patients.

RECENT FINDINGS

It has been shown that clonal large granular lymphocyte (LGL) expansions arise from chronic antigenic stimulation, leading to resistance to apoptosis. All the above findings have facilitated the diagnosis of LGLL and provided insights in the pathogenesis of the disease. At present, there is no standard first-line therapy for the disease. Immunosuppressive agents are the treatment routinely used in clinical practice. However, these agents have a limited capacity to eradicate the LGL clone and induce long-lasting remission. Advances in the knowledge of pathogenesis have made it possible to explore new therapeutic targets with promising results. Since LGLL is a rare disease, international efforts are needed to carry on prospective clinical trials with new potentially active drugs that could include a large number of patients.

Isolated anemia in patients with large granular lymphocytic leukemia (LGLL)

Patients with large granular lymphocytic leukemia (LGLL) frequently present with neutropenia. When present, anemia is usually accompanied by neutropenia and/or thrombocytopenia and isolated anemia is uncommon. We evaluated a cohort of 244 LGLL patients spanning 15 years and herein report the clinicopathologic features of 34 (14%) with isolated anemia. The patients with isolated anemia showed a significantly male predominance (p = 0.001), a lower level of hemoglobulin (p < 0.0001) and higher MCV (p = 0.017) and were less likely to have rheumatoid arthritis (p = 0.023) compared to the remaining 210 patients. Of the 34 LGLL patients with isolated anemia, 13 (38%) presented with pure red cell aplasia (PRCA), markedly decreased reticulocyte count and erythroid precursors, and more transfusion-dependence when compared to non-PRCA patients. There was no other significant clinicopathologic difference between PRCA and non-PRCA patients. 32 patients were followed for a median duration of 51 months (6-199). 24 patients were treated (11/11 PRCA and 13/21 non-PRCA patients, p < 0.02). The overall response rate to first-line therapy was 83% [8/11 (72.7%) for PRCA, 12/13 (92.3%) for non-PRCA], including 14 showing complete response and 6 showing partial response with a median response duration of 48 months (12-129). Half of non-PRCA patients who were observed experienced progressive anemia. During follow-up, no patients developed neutropenia; however, 5/27 (18.5%) patients developed thrombocytopenia. No significant difference in overall survival was noted between PRCA and non-PRCA patients. In summary, this study demonstrates the unique features of LGLL with isolated anemia and underscores the importance of recognizing LGLL as a potential cause of isolated anemia, which may benefit from disease-specific treatment. LGLL patients with PRCA were more likely to require treatment but demonstrated similar clinicopathologic features, therapeutic responses, and overall survival compared to isolated anemia without PRCA, suggesting PRCA and non-PRCA of T-LGLL belong to a common disease spectrum.

Toward a Better Classification System for NK-LGL Disorders

Large granular lymphocytic leukemia is a rare lymphoproliferative disorder characterized by a clonal expansion of T-lineage lymphocyte or natural killer (NK) cells in 85 and 15% of cases respectively. T and NK large granular leukemia share common pathophysiology, clinical and biological presentation. The disease is characterized by cytopenia and a frequent association with autoimmune manifestations. Despite an indolent course allowing a watch and wait attitude in the majority of patients at diagnosis, two third of the patient will eventually need a treatment during the course of the disease. Unlike T lymphocyte, NK cells do not express T cell receptor making the proof of clonality difficult. Indeed, the distinction between clonal and reactive NK-cell expansion observed in several situations such as autoimmune diseases and viral infections is challenging. Advances in our understanding of the pathogenesis with the recent identification of recurrent mutations provide new tools to prove the clonality. In this review, we will discuss the pathophysiology of NK large granular leukemia, the recent advances in the diagnosis and therapeutic strategies.

Neutropenia and Large Granular Lymphocyte Leukemia: From Pathogenesis to Therapeutic Options

Large granular lymphocyte leukemia (LGLL) is a rare lymphoproliferative disorder characterized by the clonal expansion of cytotoxic T-LGL or NK cells. Chronic isolated neutropenia represents the clinical hallmark of the disease, being present in up to 80% of cases. New advances were made in the biological characterization of neutropenia in these patients, in particular STAT3 mutations and a discrete immunophenotype are now recognized as relevant features. Nevertheless, the etiology of LGLL-related neutropenia is not completely elucidated and several mechanisms, including humoral abnormalities, bone marrow infiltration/substitution and cell-mediated cytotoxicity might cooperate to its pathogenesis. As a consequence of the multifactorial nature of LGLL-related neutropenia, a targeted therapeutic approach for neutropenic patients has not been developed yet; moreover, specific guidelines based on prospective trials are still lacking, thus making the treatment of this disorder a complex and challenging task. Immunosuppressive therapy represents the current, although poorly effective, therapeutic strategy. The recent identification of a STAT3-mediated miR-146b down-regulation in neutropenic T-LGLL patients emphasized the pathogenetic role of STAT3 activation in neutropenia development. Accordingly, JAK/STAT3 axis inhibition and miR-146b restoration might represent tempting strategies and should be prospectively evaluated for the treatment of neutropenic LGLL patients.

Large Granular Lymphocytic Leukemia: From Immunopathogenesis to Treatment of Refractory Disease

Large Granular Lymphocyte Leukemia (LGLL) is a rare, chronic lymphoproliferative disorder of effector cytotoxic T-cells, and less frequently, natural killer (NK) cells. The disease is characterized by an indolent and often asymptomatic course. However, in roughly 50% of cases, treatment is required due to severe transfusion-dependent anemia, severe neutropenia, or moderate neutropenia with associated recurrent infections. LGLL represents an interesting disease process at the intersection of a physiological immune response, autoimmune disorder, and malignant (clonal) proliferation, resulting from the aberrant activation of cellular pathways promoting survival, proliferation, and evasion of apoptotic signaling. LGLL treatment primarily consists of immunosuppressive agents (methotrexate, cyclosporine, and cyclophosphamide), with a cumulative response rate of about 60% based on longitudinal expertise and retrospective studies. However, refractory cases can result in clinical scenarios characterized by transfusion-dependent anemia and severe neutropenia, which warrant further exploration of other potential targeted treatment modalities. Here, we summarize the current understanding of the immune-genomic profiles of LGLL, its pathogenesis, and current treatment options, and discuss potential novel therapeutic agents, particularly for refractory disease.

A non-cytotoxic regimen of decitabine to treat refractory T-cell large granular lymphocytic leukemia

We report on a novel, successful, non-cytotoxic therapy to treat multiply-refractory T-LGL in an elderly patient.