Long-term follow-up of patients with hairy cell leukaemia after treatment with pentostatin or cladribine

We report the long-term follow-up results on two groups of patients with hairy cell leukaemia (HCL) treated with either pentostatin (deoxycoformycin) or cladribine (2-chlorodeoxyadenosine). 165 HCL patients received treatment with pentostatin (between 1986 and 1994), and 45 were treated with cladribine (between 1992 and 1997). Age and sex characteristics were similar in the two groups. 38 patients in the pentostatin group and 12 in the cladribine group were previously untreated. 22 patients in the cladribine group had received prior treatment with pentostatin; four were resistant, 17 had relapsed following partial (four) or complete (13) responses, and one was not evaluable for response. The response rates were the same in the two groups: 82% complete response (CR), 15% partial response (PR) for pentostatin and 84% CR, 16% PR for cladribine. Relapse rates were 24% for pentostatin and 29% for cladribine after median follow-up of 71 and 45 months respectively. At 45 months, however, the relapse rate for pentostatin was only 9.7%. We found a statistically significant difference in the disease-free interval (DFI) between the two groups suggesting that patients may relapse more quickly after cladribine. The majority of relapsed patients achieved second remissions following further therapy with either pentostatin or cladribine, with no evidence of cross resistance between the two agents. The 5-year survival for all patients was 97% and treatment- related toxicity was low. We conclude that both pentostatin and cladribine induce durable remissions in the majority of HCL patients. Longer follow-up is required to establish whether some patients are cured as there is no plateau in DFI, and which of these two agents may be the treatment of choice.     

Revised guidelines for the diagnosis and management of hairy cell leukaemia and hairy cell leukaemia variant*

The British Committee for Standards in Haematology first produced guidelines for the diagnosis and management of hairy cell leukaemia and hairy cell leukaemia variant in 2000. This revision updates those guidelines and covers the areas of diagnosis, treatment and assessment of response to therapy.     

A morphometric study of bone marrow angiogenesis in hairy cell leukaemia with clinicopathological correlations

Bone marrow angiogenesis has recently been implicated in the pathophysiology and course of various haematological malignancies. Little is known, however, about the significance of this phenomenon in hairy cell leukaemia (HCL). We evaluated various morphometric characteristics of microvessels, highlighted by means of anti-CD34 immunohistochemistry, in the bone marrow of 44 patients with typical HCL, before and after treatment with interferon-alpha (IFN-alpha). Overall, bone marrow from 103 HCL patients and 20 controls was examined. Microvessel density (MVD) and several size- and shape-related parameters were quantified in the region of most intense vascularization using image analysis. MVD, size-related parameters and the percentage of branching microvessels were higher in HCL than in controls. Likewise, perimeter counts were higher in partial/non-responders than in complete responders. Achievement of complete response was accompanied by smaller calibre microvessels. IFN-alpha induced a decrease in MVD and branching values in cases with diffuse marrow involvement. In univariate analysis, progression-free survival was adversely affected by MVD, branching and major axis length. Multivariate analysis indicated that MVD/branching independently affected progression-free survival and the likelihood of complete response. Our data suggest that the generation of bone marrow microvessels indicated an increased risk of progression and IFN-alpha treatment failure in HCL. Furthermore, the prognostic significance of angiogenesis requires the concomitant assessment of MVD and the complexity of the microvascular network.     

How I manage patients with hairy cell leukaemia

Patients with hairy cell leukaemia (HCL ) have highly favourable outcomes after purine analogue therapy. However, most patients subsequently relapse and require re‐treatment. A minority of patients develop purine analogue‐refractory disease. Targeted therapies have improved outcomes for such patients. Recently, the BRAF V600E mutation was identified in most patients with classical HCL , resulting in constitutive mitogen‐activated protein kinase pathway activation; impressive responses are achieved in heavily pre‐treated patients with BRAF inhibition. The CD 22‐targeted immunoconjugate moxetumomab pasudotox and BTK inhibitor ibrutinib also achieve responses in relapsed and refractory patients. HCL variant and the IGHV 4‐34 molecular variant of HCL lack BRAF mutation and have inferior outcomes with standard purine analogue therapy. The addition of rituximab to purine analogues achieves very high rates of minimal residual disease‐negative complete remission and improves outcomes for patients with HCL variant. Given the rarity of HCL , optimal integration of novel therapies into treatment algorithms will require well‐designed, collaborative studies.     

Fatal cold anti-i autoimmune haemolytic anaemia complicating hairy cell leukaemia

Hairy cell leukaemia (HCL) is a rare lymphoproliferative disorder associated with pancytopenia, splenomegaly and the presence of typical hairy B lymphocytes in the bone marrow and/or peripheral blood. The most significant complication relates to opportunistic infections that arise as a consequence of neutropenia and monocytopenia. HCL is occasionally associated with systemic autoimmune disorders including polyarteritis nodosa and rheumatoid disease. Secondary autoimmune haemolytic anaemia (AIHA) appears to be rare. We report on two cases of HCL complicated by fatal cold anti-i AIHA. Fulminant haemolysis causing death is rare in cold AIHA and only a few individual cases have been reported, none having anti-i specificity.     

Analysis of leucocyte differentiation antigens in blood and bone marrow in patients with refractory anaemia (RA) and RA with sideroblasts. Prognostic implications of sequential and follow-up data

34 patients with primary myelodysplastic syndrome (MDS), initially diagnosed as subtypes refractory anaemia (RA) and RA with ringed sideroblasts (RA-S), were followed to investigate the distribution of lymphoid and myeloid differentiation antigens in the blood and bone marrow in search of potential prognostic significance with regard to progression to RA with an excess of blasts (RAEB) or acute myeloid leukaemia, and for relations to clinical, morphological and cytogenetic findings. Patients who later progressed to RAEB had significantly decreased percentages of anti-T8 positive T-suppressor cells in the blood at diagnosis compared to those who did not (p = 0.05). Sequential analysis showed a decrease with time also in the percentages of anti-T8-positive cells (p = 0.05). In the bone marrow, progressing patients initially showed significantly increased percentages of anti-My9-positive immature myeloid cells (p less than 0.001), and the percentages of anti-My9-positive cells in the bone marrow increased with time (p less than 0.005). Analysis of the pooled data revealed a statistically significant relation between increasing percentages of anti-My9-positive cells and the frequencies of clonally abnormal (p less than 0.001) and abnormal (p = 0.004) metaphases.     

Low-dose cladribine for symptomatic hairy cell leukaemia

Cladribine is an effective therapy for hairy cell leukaemia (HCL), but the standard regime is frequently complicated by neutropenic fever and prolonged T-cell depression. We studied 102 patients with active HCL following treatment with various doses of cladribine given for 7 d. Two patients received 1 mg cladribine/m²/d without toxicity or effect. Eight subsequent patients received 2 mg cladribine/m²/d, and normalized cytopenia as quickly as 94 control patients receiving a standard dose (3.4mg/m² or 0.085 mg/kg), with significantly less lymphopenia and a similar complete remission rate.     

Severe decrease in peripheral blood dendritic cells in hairy cell leukaemia

Clinical studies in hairy cell leukaemia (HCL) have linked the frequent occurrence of infections due to intracellular pathogens and a profound monocytopenia. More recently, dendritic cells (DC), a subset of which are related to monocytes, were shown to be the professional antigen-presenting cells which stimulate the adaptive immune response. Using membrane markers and flow cytometry, we determined in peripheral blood whether various DC subsets and monocytes were impaired in HCL. Lymphoid and myeloid DC were virtually absent in five HCL patients with active disease. After treatment, both DC and monocytes recovered slowly. The decrease in DC suggests that defective antigen presentation could affect susceptibility to intracellular pathogens in HCL.     

Hypereosinophilia during 2-chlorodeoxyadenosine treatment for hairy cell leukaemia

A 43-year-old male with newly diagnosed hairy cell leukaemia underwent a single course of 2-chlorodeoxyadenosine (2-CdA). Skin rash, facial swelling and marked eosinophilia developed 20 d after treatment and were resolved by 7 d of steroid therapy. Eosinophil peak in peripheral blood reached 1230 cells/μl. Flow cytometric analysis of the eosinophil population showed a high expression of the IL-2 receptor α-chain (CD25), representing up to 94% of gated cells. HLA-DR and CD4 antigens were constantly negative; eosinophils strongly reacted with the secretory form of the eosinophil cationic protein (ECP), recognized by EG2 monoclonal antibody. IL-5 serum levels were markedly elevated at the onset of eosinophilia, returned to normal levels after its disappearance and positively correlated with eosinophil count ( r  = 0.94, P  = 0.016). Eosinophilia is an uncommon finding after treatment with 2-CdA. It is unclear whether these phenomena represented a true allergic reaction to the drug or the effect of massive tumour cell lysis and haemopoietic pancytopenia with immunosuppression, which induced the release of IL-5 and possibly other cytokines.     

Lack of efficacy of pyridoxine (vitamin B6) treatment in acquired idiopathic sideroblastic anaemia, including refractory anaemia with ring sideroblasts

Pyridoxine, or vitamin B6, is commonly used to treat acquired idiopathic sideroblastic anaemia (AISA, including refractory anaemia with ring sideroblasts), but the efficacy of this therapy in an unselected AISA population (i.e. patients without confirmed ALAS2 or other pyridoxine-responsive germline mutations) has not been established. We reviewed clinical data from 231 patients with AISA and found that 42% of 203 evaluable patients had been treated with pyridoxine. Only 6.8% of pyridoxine-treated patients experienced a haemoglobin improvement (≥ 1.5 g/dL) meeting 2006 International Working Group for Myelodysplastic Syndromes standardised response criteria. As some patients received combination therapy with erythropoietin or other agents, improvement could be attributed to pyridoxine monotherapy in only one patient (1.4%). Smaller, less meaningful increments in haemoglobin levels of 0.5 g/dL were observed in 13.5% of patients. Response to therapy did not correlate with International Prognostic Scoring System (IPSS) risk group or multilineage vs unilineage dysplasia. New symptomatic peripheral neuropathy was noted in 2.3% of patients treated with pyridoxine. In this large series of unselected patients with sideroblastic anaemia, pyridoxine therapy was ineffective and was associated with a risk of adverse effects. Pyridoxine therapy should be reserved for patients with known or suspected pyridoxine-responsive mutations.     

VH gene expression in hairy cell leukaemia

Hairy cells are characterized by their typical morphology and expression of specific surface antigens. Although their B-cell origin is now confirmed, their exact position in B-cell development remains unclear. To better define the origin of hairy cells, we analysed the immunophenotype and the Ig VH nucleotide sequence of seven cases of hairy cell leukaemia (HCL). Six of them were typical HCL and the remaining case corresponded to a variant HCL. Analysis of sequenced VH genes revealed that the VH1 family was used in one case, VH2 in one, VH3 in two, VH4 in two and VH5 in one. No preferential usage of VH genes was observed in this small series. In five cases high rates of somatic mutations were observed, with a predominance of mutations and replacements in CDR regions for three, indicating that these cells originate from cells that have been exposed to the hypermutation mechanism. The distribution of mutations in our small series provides some evidence of a selective mutational process.     

Long-term follow-up of 233 patients with hairy cell leukaemia, treated initially with pentostatin or cladribine, at a median of 16 years from diagnosis

Hairy cell leukaemia (HCL) was first described 50 years ago. Median survival was then 4 years. The purine analogues, introduced in the 1980s, transformed this prognosis. We reviewed data retrospectively from 233 patients, treated with pentostatin ( n  = 188) or cladribine ( n  = 45), to investigate the current long-term outlook. Median follow-up was 16 years. There were no significant differences in outcome between the two agents. Overall, the complete response (CR) rate was 80% and median relapse-free survival was 16 years. After relapse ( n  = 79) or non-response ( n  = 5), 26 patients received pentostatin and 58 cladribine; 69% achieved CR and median relapse-free survival was 11 years. After third-line therapy ( n  = 23), 50% achieved CR and median relapse-free survival was 6·5 years. However, CRs were equally durable, whether after first, second or third-line therapy. Complete responders and those with both haemoglobin >100 g/l and platelet count >100 × 10⁹/l before treatment had the longest relapse-free survival ( P  < 0·0001). Patients still in CR at 5 years had only a 25% risk of relapse by 15 years. Outcomes for patients with recurrent disease improved with the monoclonal antibody rituximab, combined with either purine analogue. Overall only eight patients died of HCL-related causes. Patients achieving a CR can expect a normal lifespan.     

Evidence for a paracrine pathway of B-cell stimulation in hairy cell leukaemia

It is a well-known phenomenon that the growth of malignant B-lymphocytes, i.e. hairy cells, is regulated by cytokines. Several investigators have suggested that the stimulating cytokines are produced by the malignant B cells themselves, indicating an autocrine growth regulation. In this paper we demonstrate that T-lymphocyte clones produce soluble mediators which stimulate the growth of malignant B lymphocytes. The incidence of the growth-stimulating T-cell clones derived from peripheral blood is identical in patients with hairy cell leukaemia (HCL) and healthy controls. About 50% of the clones stimulate the growth of hairy cells, but not the growth of purified B lymphocytes of healthy donors. The stimulating activity of a single clone varies when tested on different hairy cells. Interferon alpha (IFNa), but not antibodies against tumour necrosis factor alpha (TNFQ) or interleukin-2 (IL-2), completely inhibit the growth-stimulating activity. Our results indicate that a paracrine growth regulation has to be considered in addition to the postulated autocrine loop in the growth regulation of malignant B cells.     

Rituximab as treatment for minimal residual disease in hairy cell leukaemia

Abstract:  Purine analogues have dramatically improved the outcome of patients affected by hairy cell leukemia (HCL), although complete eradication of disease was achieved in few cases. The purpose of this study was to evaluate the role of Rituximab in eradicating minimal residual disease (MRD) in HCL patients after a pre-treatment with 2-chloro-deoxy-adenosine (2-CdA). Ten patients received four cycles of Rituximab after administration of Cladribrine. Before starting anti-CD20 antibody, two patients were in complete remission, six in partial remission and two showed no significant response to Cladribrine. All cases resulted IgH-positive. Median time from the last 2-CdA infusion was 5.7 months. Eight of 10 patients [four in partial remission (PR), two in complete remission (CR) and two unresponsive after 2-CdA] were evaluable for response. Two months after the end of anti-CD20 therapy, all evaluated patients presented a complete haematological remission. Moreover, Rituximab increased percentage of molecular remission up to 100% 1 yr after the end of treatment. Interestingly, in all cases but one, including those persistently polymerase chain reaction (PCR)-positive, semi-quantitative molecular analyses showed MRD levels lower than those found before Rituximab administration. Toxicity was very mild. The present results not only confirm the therapeutic effect of Rituximab, but also show its relevance in eradicating MRD in HCL.     

Immunologic effects on the haematopoietic stem cell in marrow failure

Acquired bone marrow failure (BMF) syndromes comprise a diverse group of diseases with variable clinical manifestations but overlapping features of immune activation, resulting in haematopoietic stem and progenitor cells (HSPC) damage and destruction. This review focuses on clinical presentation, pathophysiology, and treatment of four BMF: acquired aplastic anaemia, large granular lymphocytic leukaemia, paroxysmal nocturnal haemoglobinuria, and hypoplastic myelodysplastic syndrome. Autoantigens are speculated to be the inciting event that result in immune activation in all of these diseases, but specific pathogenic antigens have not been identified. Oligoclonal cytotoxic T cell expansion and an active role of proinflammatory cytokines, primarily interferon gamma (IFN-γ) and tumor necrosis factor alpha (TNF-α), are two main contributors to HSPC growth inhibition and apoptosis in BMF. Emerging evidence also suggests involvement of the innate immune system.     

Primary splenic hairy cell leukaemia: a case report and review of the literature

Hairy cell leukaemia affecting primarily the spleen is a very rare feature of this disease at presentation. Splenectomy in such cases would seem to provide a cure. We report a case of primary splenic hairy cell leukaemia in which clinical and haematological remission were achieved after splenectomy, and we review the literature.     

Treatment outcomes and secondary cancer incidence in young patients with hairy cell leukaemia

Repeated therapy of hairy cell leukaemia (HCL) with treatments that have potential long‐term toxicities has raised concerns regarding increased risk for younger patients. We compared clinical outcomes and disease complications in 63 patients with HCL aged ≤40 years at diagnosis with 268 patients >40 years treated at Memorial Sloan Kettering Cancer Center. The rate of complete remission following initial therapy was 87% and 83% (P = 0·71) and estimated 10‐year overall survival was 100% and 82% (P = 0·25) in younger and older patients, respectively. Younger patients required therapy earlier and had a significantly shorter time between first and second therapy (median: 63 months vs. 145 months) (P = 0·008). Younger patients required significantly more lines of therapy during follow‐up. The 10‐year cumulative incidence of secondary malignancies in young and old patients was 0·205 and 0·287, respectively (P = 0·22). The incidence of secondary cancers in patients aged >40 years at diagnosis increased with the number of treatments for HCL (P = 0·018). These results highlight that young patients with HCL have shorter responses to treatment and require more lines of therapy to maintain disease control, while attaining similar long‐term survival. This has implications in the design of future clinical trials given our findings that secondary malignancies increase with more chemotherapy exposure.