How I treat hairy cell leukemia

Abstract

The description of hairy cell leukemia as a specific clinical entity was published 50 years ago. The clinical outcome for patients was hampered by ineffective chemotherapy, and splenectomy was the major therapeutic approach to improve peripheral blood counts. The median survival after diagnosis was 4 years. With the introduction of ␣-interferon in 1984, marked improvements in patient responses were observed. Shortly thereafter, the introduction of the purine nucleoside analogs transformed this disease into a highly treatable form of leukemia, and patients with the classic form of this rare leukemia now have a near-normal life expectancy. However, other clinical entities mimicking this disease do not respond; thus, accurate diagnosis is important. Immunophenotypic features in classic hairy cell leukemia show that the leukemic cells express CD11c, CD25, CD103, and CD123 and display bright CD20. Despite the high percentage of durable complete remissions with modern therapy, the long-term disease-free survival curves have not reached a plateau. Many patients who achieve a complete remission by morphologic criteria have minimal residual disease demonstrable by either flow cytometry or immunohistochemical staining, and this population may be at higher risk for earlier relapse. Continued clinical research is essential to optimize therapy for this disease. (Blood. 2010;115:21-28) IntroductionIn 1958, Bouroncle et al described a series of patients with leukemic reticuloendotheliosis. 1 Although this collection of cases established that the previously described isolated reports actually represented a distinct hematologic malignancy, the classic manuscript contained a very thorough presentation of the many clinical facets of this disease now known as hairy cell leukemia (HCL). Furthermore, it established that therapeutic intervention was limited either to careful titration of alkylating agents or to splenectomy. The ability to alter the clinical course of the patients with this rare form of leukemia did not substantially change until the introduction of ␣-interferon in 1984. 2 Shortly thereafter, observations that a purine nucleoside analog (pentostatin) could induce a high degree of complete remissions (eg, 75%-89%) in this previously "untreatable" chronic leukemia changed the natural history of HCL in record time. [3][4][5][6][7][8] Another purine nucleoside analog (cladribine) produced remarkably high remission rates (eg, 91%) with a single course of therapy. 9,10 The outstanding results with this agent delivered as a single course of therapy led to cladribine being the initial therapy selected by most hematologists. Many of the initial studies with this agent excluded patients with active infection from enrollment, but studies from multiple institutions confirmed the high complete remission rate with this drug. [11][12][13][14] Thus, patients who are treated with either purine nucleoside analog as front-line therapy will achieve a high rate of complete remission (75%-90%). 7,10 The long-term studies reported at 5 to 10...

Clinical and laboratory features of leukemias at the time of diagnosis: An analysis of 1,004 consecutive patients

“…Unlike the frequency of symptoms, the spectrum of symptoms did not differ from historical studies [2,[7][8][9]15,16]. Similarly, the spectrum of findings during physical examination at the time of diagnosis did not differ from published data; however the incidence was again notably lower.…”

“…Although textbooks and reviews have described several different signs and symptoms of the various types of leukemia [1][2][3][4][5][6][7][8], the real incidence of these findings has not been described. Only a few studies specifically address this issue [9] and are usually several decades old [10,11].…”

Molecular detection of BRAF‐V600E is superior to flow cytometry for disease evaluation in hairy cell leukaemia

“…The differential diagnosis includes myelofibrosis, splenic marginal zone lymphoma and hairy cell variant (HCLv) that is CD25 negative. Making the correct diagnosis is essential as treatment with nucleoside analogues, such as cladribine and pentostatin, or with interferon or rituximab is usually highly effective in HCL [2].…”

An unusual indication for splenectomy in hairy cell leukaemia: a report of three cases with persistent splenomegaly after chemoimmunotherapy

“…Purine analogues have revolutionized the treatment of hairy cell leukaemia (HCL) with overall responses in more than 85% of patients and a median progression‐free survival (PFS) of up to 15 years (Else et al , 2009; Grever, 2010). …”