Keywords Kúcové slová: DEFINITION AND BASIC INFORMATION Hairy cell leukaemia (HCL) is a rare, chronic, slowly progressive, lymphoproliferative haematological malignancy with an incidence of approximately 0.3/100,000 people. It represents almost 2% of the incidence of all leukaemias. This malignant disease affects the B-lymphocytes and belongs to the indolent lymphomas. Leukaemic B cells developmentally stand between B chronic lymphocytic leukaemia (B-CLL) and plasmacytoma cells in the classical form (c-HCL), or between * firstname.lastname@example.org © Acta Facultatis Pharmaceuticae Universitatis Comenianae prolymphocytic leukaemia and plasmacytoma cells in the variant form (v-HCL). The name is derived from the characteristic morphology of leukaemic B cells in panoptic stain, phase contrast or electron microscopy. The cells are typically present with their hair-like cytoplasmic projections in the peripheral blood, bone marrow and an enlarged spleen. However, they can infiltrate the lymph nodes, liver or other organs in the human body. The median of average age in patients with HCL is 52 years; however, the age range is very broad, while children are not affected. The disease occurs up to four times more often in men than in women. The cause of HCL is still unknown. Amongst other exogenous risk factors, exposure to ionising radiation, organic solvents, insecticides or herbicides is being discussed (Oleske et al., 1985). Accurate diagnosis requires a multidisciplinary approach, including an experienced haematologist, oncologist, haematopathologist, and a precise haematological, genetic and biopsy centre using modern investigative procedures. ESTABLISHING THE DIAGNOSIS c-HCL is characterised by cell morphology (Figure 1) and cell arrangement in the bone marrow (hair-like projections in the peripheral blood, fried eggs appearance in the bone marrow), presentation of surface antigens (CD11c, CD20, CD22, CD25, CD103, CD123), cytochemical positivity for tartrate-resistant acid phosphatase (TRAP), immunohistochemical (CD20, DBA.44) and reticulin staining, the presence of specific annexin ANXA1, and BRAF V600E mutation. The classic form has a relatively good prognosis with long-term remission in most patients after standard treatment with purine analogues. v-HCL, which represents up to 10% of HCL, lacking expression of CD25, annexin A1, presents BRAF wild-type genotype, and the response for TRAP is modest to none. These patients respond poorly to purine analogues, with only partial response in less than 50% and relatively poor overall survival from diagnosis. HCL expressing the IGHV4-34 (14q32.33) immunoglobulin rearrangement has a poor prognosis like vHCL, whether immunophenotypically consistent with v-HCL or c-HCL (Arons et al., 2009). Approximately in all cases of c-HCL in peripheral blood, pancytopenia of varying degree is present, most often leucocytopenia expressed with neutropenia, and severe monocytopenia. The incidence of leucocytosis with absolute lymphocytosis is sometimes extreme, ranging from 15 to 400 × 109/l, accompanied by v-HCL. The majority of patients have thrombocytopenia, which is often severe and accompanied by bleeding tendency. Anaemia of varying degrees is usually with normal mean corpuscular volume and mild anisocytosis and poikilocytosis. Low blood cell counts result from progressive bone marrow failure caused by a combination of leukaemic infiltration, suppressive cytokines (TNF-) and reticulin fibrosis, and as a consequence of splenomegaly. Circulating hairy cells can be demonstrated in more than 95% of cases (Figure 2). Bone marrow aspirate accompanied by reticulin fibrosis is diagnostically important, sometimes causing dry tap, but the morphology of HCL in blood smear and trephine biopsy is typical of the diagnosis. The HCL cells with a pale cytoplasm in a fine network of reticulin fibres appear in the form of fried eggs. Morphologically suspected HCL is necessary to be confirmed in the bone marrow by multiparameter flow cytometry (FC) immunophenotypic examination of HCL-presenting antigens (CD11c, CD20, CD22, CD25, CD103, CD123) (Figure 3), and at least four fluorescent parameters are needed with sensitivity of < 0.001% cells. The cytochemical or immunohistochemical (particularly TRAP and ANXA1 antibody) determination of TRAP isoenzyme 5 and annexin ANXA1, immunohistochemical analysis (IHCA) of CD20, DBA. 44 antigens, and cytogenetic analysis for gene mutation BRAF V600E are useful for additional and differential diagnostic distinction (Matutes et al., 1994, Falini et al., 2004, Tiacci et al., 2011). Infiltration of the red pulp of the spleen is responsible for the often bulky and massive splenomegaly with the formation of "blood lakes", which are blood-filled areas surrounded by hairy cells, formed by disruption of splenic sinusoidal vascular architecture, while the white pulp obliterates in time. Evidence of hairy cells can also be found through electron microscopy showing characteristic wrinkled surface with cytoplasmic projections that line the entire surface of the cells displaying the ribosomal lamellar complex within. The values of serum soluble IL-2 receptors (IL-2R, CD25) are high and the level correlates with disease activity (Steis et al., 1988). CLINICAL MANIFESTATION Clinical presentation results from haematological abnormalities associated with pancytopenia, splenomegaly (present in up to 90% of the advanced stages), to less common hepatomegaly in 4050%, abdominal lymphadenopathy in 1520% and peripheral lymphadenopathy in 10% of patients. For most patients suffering from non-specific symptoms such as increased fatigue, malaise and general weakness, their condition is often due to ongoing infection, splenomegaly or abnormal number of blood cells in the blood count. Lymphoproliferative malignancies (including HCL) accompany B-cells such as non-infectious fever of unknown origin, excessive sweating and weight loss of 10% in the last 6 months. Untreated HCL is fatal with an increasing number of bleeding and infectious complications. The incidence of infections is dependent on the degree of neutropenia and monocytopenia as well as the decrease of antigen-presenting dendritic cells and T-cell immunity disorders. Approximately 15% of patients have various autoimmune disorders such as vasculitis, polyarthritis nodosa, cryoglobulinemia, glomerulonephritis, autoimmune haemolytic anaemia, immune thrombocytopenia, rheumatoid arthritis, thyroiditis, pernicious anaemia or formation of antibodies to coagulation factor VIII (Polliack, 2002). Some studies reported an increased rate of secondary neoplasms (Hisada et al., 2007). TREATMENT Indication for the treatment of patients with HCL is mainly correction in the progression of cytopenia and clinical problems associated with anaemic syndrome, recurrent infections and bleeding. Rarely, asymptomatic patients with nonsevere cytopenias and mild splenomegaly are not in need Figure 1. Hairy cell B-lymphocyte in the peripheral blood smear. Figure 1.: Hairy cell B-lymphocyte in the peripheral blood smear. Figure 2. Peripheral blood with hairy cells in panoptic stain. Figure 2: Peripheral blood with hairy cells in panoptic stain. Figure 3. Flow cytometry analysis of the hairy cells (blue). of immediate treatment. In order to decide on the onset of therapy, the dynamics of decline of various haematological parameters in the time period, in addition to the absolute count of blood elements, are monitored. Therapy is indicated for the symptomatic anaemia with a decrease in haemoglobin Hb < 80100 g/l, thrombocytopenia Tr < 50100×109/l, neutropenia Neu < 0.51.0×109/l as well as leucocytosis in peripheral blood with a high proportion of hairy cells (v-HCL), recurrent infections, symptomatic splenomegaly, massive or painful lymphadenopathy, autoimmune disorders including vasculitis and osteolytic bone lesion (Seshadri and Seshadri, 2001). The goal of the therapy is to achieve CR characterised by the disappearance of the hairy cells from peripheral blood and bone marrow, treatment of clinical signs present at the time of diagnosis, and normalisation of organ manifestations, such as splenomegaly, hepatomegaly and lymphadenopathy. Before 1984, splenectomy was the only standard treatment modality in almost all patients. By removing the spleen, it is not possible to induce pathological remission in bone marrow since over time there is still progression. After splenectomy, half of the patients require systemic therapy over a median interval of 8.3 months (Golde, 1982). Today, it is used only as a palliative procedure if all other treatment options fail, or as a diagnostic method in rare cases. Unlike splenectomy, interferon- (IFN-) can partially eradicate hairy cells from the bone marrow, but its potential is not curative. It has been used to treat HCL since 1984 with RRs up to 8090%, mostly as partial remissions (PRs) and CRs in only 530%. Overall survival in 5th year after treatment exceeds 85%; relapses occur after a median of 1825 months (Frassoldati et al., 1994). At the present time, the standard therapy consists of the purine analogues 2-dCF and 2-CdA, with responses to treatment in nearly all patients (2-dCF RR=83100%, 2-CdA RR=87100%), mostly with CRs (2-dCF CR=4289%, 2-CdA CR=7591%). Long-lasting remissions are achieved with a significant prolongation of overall survival of HCL patients even if the complete elimination of the disease is still not possible. The median to progression and relapse is 37.4 months (Robak et al., 1999). The presence and quantity of minimal residual Figure 3: Flow cytometry analysis of the hairy cells (blue). disease (MRD) in the bone marrow affect the risk of early and late relapses and progression. It is assumed that a certain degree of MRD is present in each patient after treatment; its detection depends on the technique used (FC, immunohistochemistry, polymerase chain reaction (PCR)). Today, HCL is considered as a highly treatable disease, despite the fact that complete eradication (complete cure) is not fully achievable, depending on persistent MRD with indolent behaviour. Other promising therapies that have proven their efficacy in refractory or relapsed patients, possibly with the potential to eradicate MRD, are some medicines used in the treatment of B-CLL or other malignancies (rituximab, alemtuzumab, fludarabine, bendamustine), experimental immunotoxins (BL22, LMB-2, HA22), tyrosine kinase inhibitors (ibrutinib) and B-Raf enzyme inhibitors (vemurafenib). Due to the relatively low incidence of HCL, it is necessary to await the results of larger studies to confirm the effectiveness and order in treatment. THERAPY AND RESULTS ON NCI By comparing these data at the Department of Clinical Oncology of the National Cancer Institute (NCI) over 15 years (19962010), we have confirmed our diagnostic skill in determining the HCL diagnosis, and the results of different therapeutic approaches from splenectomy, IFN-, 2-CdA to monoclonal antibody rituximab (anti-CD20). We have diagnosed and treated 38 patients (31 men, 7 women). To confirm the diagnosis, in addition to the clinical presentation, we have used morphological examination of peripheral blood and bone marrow, FC with the determination of CD markers and immunohistochemistry of trephine biopsy. One patient with hypersplenism was diagnosed after diagnostic splenectomy. In other patients, c-HCL was confirmed by morphological, immunophenotypic and immunohistochemical analysis of bone marrow. v-HCL was not present in any of our patients. The median age was 52 years at the time of diagnosis (21 77 years), and the ratio of affected men to women was 45:1. The clinical manifestations of HCL we observed are weakness and fatigue in 61%, B-symptoms in 42%, infection at the time of diagnosis in 55%, bleeding tendency in 34% and the DNA PCR in the absence of disease detectable by morphofeeling of pressure in the left upper abdomen in 11% of pa- logic criteria, ranging from 15% to 50% or more depending tients. Splenomegaly was verified by ultrasound or CT scan on the method of detection used (Grever, 2010). The presence and occurred in 95% of patients (except one patient after and the degree of MRD determined the risk of relapse and splenectomy in the past for other reason); hepatomegaly and the survival rate after 5 and 10 years. MRD was present in 91% lymphadenopathy were identified in approximately a third of patients with relapse, compared with a 54% incidence in of patients. Autoimmune phenomena in six of the patients patients without relapse. HCL relapsed with a median of 31.5 (16%) manifested as vasculitis, rheumatoid arthritis, autoim- months after the first treatment and occurred in 42% (16 pamune haemolytic anaemia, periarteritis nodosa and Sjögren's tients) of patients, and more times in 10% (4 patients). In the syndrome along with autoimmune hypothyroidism. We re- second-line, we administered 2-CdA in monotherapy (nine pacorded the occurrence of benign and malignant tumours tients), 2-CdA with rituximab (anti-CD20) (one patient), rituxiamong HCL patients in eight cases (21%), with six malignan- mab in monotherapy (one patient) and IFN- (three patients). cies including cutaneous basal cell carcinoma, carcinoma of Of the total group of 38 patients, death occurred in 6 cases, the colon, prostate, thyroid and bladder cancer. with a median of 50 months from the first treatment. Three As standard first-line therapy in 34 patients, we indicated 2-CdA patients died following repeated relapse of HCL and complicabecause of its easy administration (treatment lasts only one cy- tions arising from the progression, while the remaining three cle), availability and favourable toxicity profile. 2-CdA proved deaths were caused by cerebrovascular stroke, sudden cardiac to be effective even in 9 from 10 relapsed patients (CR 70%, death and advanced colon carcinoma with metastases in liver. PR 20%). The remaining four patients were cured in the first- We found the presence of atypical larger lymphoid hairy cells line by splenectomy (three patients) and one with IFN-. The in blast transformation with identical immunophenotype at original scheme of continuous administration of 2-CdA (7 days the time of diagnosis and loss of response to 2-CdA and rituxiat a dose of 0.1 mg/kg/day (18 patients)) was later replaced mab treatment in each of the three patients who died of HCL. with more convenient administration of 0.14 mg/kg/day in Morphological changes of larger atypical hairy cells, with poly2 hour infusion (2 patients) or with a subcutaneous bolus morphism and variability in size from small to medium, more (14 patients) in 5 consecutive days. The treatment response of compact chromatin and more basophilic cytoplasm still with a single cycle of 2-CdA in the first-line was 100% in our group "hair-like" projections, and CD20 and DBA.44 positivity had a faof patients, with 79% (27 patients) of CRs, and 21% (7 patients) tal prognosis. Together, 16 patients with relapse of the disease of PRs (Greksák et al., 2011). Out of the patients who under- survived 3 years, 94% (15 patients) survived 5 years and 81% went the first treatment, 95% survived three years, 89% five (13 patients) survived 10 years after the first progression (Figyears, and 87% ten years (Figure 4). In the majority of patients ure 5). An important factor responsible for the relapsed HCL is (69%), MRD of the variable quantity (120%) detected by FC or the sensitivity to first-line therapy and the extent of persistent IHCA method remained in the bone marrow. MRD is defined infiltrate in the bone marrow after treatment (MRD), quantias identification of persistent HCL after treatment using im- fied by the FC and immunochemistry (IC) methods (Greksák, munophenotypic analysis, immunohistochemical staining or 2012). 100 90 patients [%] 80 70 60 50 40 0 50 100 150 time [months] Figure 4: Overall survival after first line treatment of 38 patients with HCL. Figure 4. Overall survival after first line treatment of 38 patients with HCL. Figure 4: Overall survival after first line treatment of 38 patients with HCL. patients [%] 40 0 50 100 150 time [months] Figure 5: Difference in survival patients patients with (red) and without (blue) relapse of Figure 5. Difference in survival betweenbetweenwith (red) and without (blue) relapse of HCL. Crossing lines caused by death of 2 older patients at 26 and 31 months from other reason than HCL. HCL. Crossing lines caused by death of 2 older patients at 26 and 31 months from other reason than HCL. CONCLUSIONS Despite the low incidence of HCL, in our group of 38 patients, we verified the diagnostic and treatment methods that changed the prognosis of this originally fatal disease over the last 25 years of research. Most patients now survive for a long time in CR or with persistence of MRD without any symptoms of the disease. In addition to morphological characteristics of hairy cells, modern diagnostic techniques such as FC reveal the immunophenotypic profile of leukaemic cells; immunohistochemical analysis of biopsies and, recently, cytogenetic analysis now allow the most reliable designation of the diagnosis HCL and differentiation from other lymphoproliferative diseases. Use of new drugs, such as monoclonal antibodies, immunotoxins, tyrosine kinase inhibitors and B-Raf enzyme inhibitors, requires the results of recent studies that can clarify their position in the treatment and the therapeutic prospects for the smaller group of patients refractory to standard treatment with purine analogues (v-HCL) or with early relapsed HCL. They might have potential to eliminate MRD after first-line therapy and thereby reduce the risk of relapse (Greksák, 2010). Our results are comparable with global data and help us to verify the diagnostics and therapeutic methods that allow the long-term control of the disease and long-term survival of patients without any symptoms of relapse. Thus, HCL has become a treatable disease with a relatively good prognosis although we have not yet achieved a complete cure that may require the use of new drugs.
Acta Facultatis Pharmaceuticae Universitatis Comenianae – de Gruyter
Published: Aug 30, 2014