2010 115: 21-28 Prepublished online Oct 20, 2009; doi:10.1182/blood-2009-06-195370
How I treat hairy cell leukemia
Michael R. Grever
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From www.bloodjournal.org by on November 29, 2010. For personal use only.
How I treat
How I treat hairy cell leukemia
Michael R. Grever1
of Internal Medicine, Ohio State University, Columbus
The description of hairy cell leukemia as a speciﬁc clinical entity was published 50 years ago. The clinical outcome for patients washampered 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 nucleo-
side analogs transformed this disease into a highly treatable form ofleukemia, 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 ofdurable 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 tooptimize therapy for this disease. (Blood. 2010;115:21-28)
In 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 manyclinical 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.3-8 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...