Correspondence 1027 CCR on imatinib. A recently published study also showed that 4 Smit WM, Rijnbeek M, van Bergen CA, de Paus RA, Vervenne HA, normal plasmacytoid DC number and secretion of IFN-a could van de Keur M et al. Generation of dendritic cells expressing be restored in imatinib responding CML patients.12 This may be BCR–ABL from CD34-positive chronic myeloid leukemia precur- advantageous, since leukaemic DC may not process antigen sor cells. Hum Immunol 1997; 53: 216–223. 6 5 Jiang YZ, Mavroudis D, Dermime S, Hensel N, Couriel D, normally in CML. However, disappearance of the BCR–ABL Molldrem J et al. Alloreactive CD4+ T can exert positive DC population may be disadvantageous, since DC can cytotoxicity to chronic myeloid leukaemia cells processing and then no longer present leukaemia-specific endogenously presenting exogenous antigen. Br J Haematol 1996; 93: 606–612. derived BCR–ABL peptides to the immune system. Further 6 Dong R, Cwynarski K, Entwistle A, Marelli-Berg F, Dazzi F, studies are required to define whether imatinib treatment may Simpson E et al. Dendritic cells from CML patients have altered also modify BCR–ABL directed T-cell responses. actin organization, reduced antigen processing, and impaired migration. 2003; 101: 3560–3567. 1 7 Wang C, Al-Omar HM, Radvanyi L, Banerjee A, Bouman D, Squire L Wang 1Department of Haematology, Royal Liverpool J et al. Clonal heterogeneity of dendritic cells derived from patients 1 University Hospital, Prescot St, NM Butt with chronic myeloid leukemia and enhancement of their T-cells 2 Liverpool L7 8XP, UK; MG Atherton stimulatory activity by IFN-a. Exp Hematol 1999; 27: 1176–1184. 1 2Merseyside and Cheshire Cytogenetics RE Clark 8 O’Brien SG, Guilhot F, Larson RA, Gathmann I, Baccarani M, Laboratory, Liverpool Women’s Hospital, Cervantes F et al. Imatinib compared with interferon and low-dose Crown St, Liverpool L8 7SS, UK cytarabine for newly diagnosed chronic-phase chronic myeloid leukemia. N Engl J Med 2003; 348: 994–1004. 9 Wang L, Pearson K, Pillitteri L, Ferguson JE, Clark RE. Serial References monitoring of BCR–ABL by peripheral blood real time polymerase chain reaction predicts the marrow cytogenetic response to 1 Clark RE, Dodi IA, Hill SC, Lill JR, Aubert G, MacIntyre AR et al. imatinib mesylate in chronic myeloid leukaemia. Br J Haematol Direct evidence that leukaemic cells present HLA-associated 2002; 118: 771–777. immunogenic peptides derived from the BCR–ABL b3a2 fusion 10 Auffermann-Gretzinger S, Lossos IS, Vayntrub TA, Leong W, protein. Blood 2001; 98: 2887–2893. Grumet FC, Blume KG et al. Rapid establishment of 2 Choudhury A, Gajewski JL, Liang JC, Popat U, Claxton DF, Kliche chimerism in allogeneic hematopoietic cell transplant recipients. KO et al. Use of leukemic dendritic cells for the generation of Blood 2002; 99: 1442–1448. antileukemic cellular cytotoxicity against Philadelphia chromo- 11 Dietz AB, Bulur PA, Erickson MR, Wettstein PJ, Litzow MR, Wyatt some-positive chronic myelogenous leukemia. Blood 1997; 89: WA et al. Optimizing preparation of normal dendritic cells and 1133–1142. BCR–ABL positive mature dendritic cells derived from immuno- 3 Eibl B, Ebner S, Duba C, Bock G, Romani N, Erdel M et al. magnetically purified CD14 positive cells. J Hematother Stem Cell Dendritic cells generated from blood precursors of chronic Res 2000; 9: 95–101. myelogenous leukemia patients carry the Philadelphia transloca- 12 Mohty M, Jourdan E, Ben Mami N, Vey N, Damaj G, Blaise D et al. tion and can induce a CML-specific primary cytotoxic T-cell Imatinib and plasmacytoid dendritic cell function in chronic response. Genes Chromosomes Cancer 1997; 20: 215–223. myeloid leukemia patients. Blood 2004, Jan 8 [Epub ahead of print].

Immunophenotypic normalization of aberrant mast cells accompanies histological remission in imatinib-treated patients with eosinophilia-associated mastocytosis

Leukemia (2004) 18, 1027–1029. doi:10.1038/sj.leu.2403329 A 30-year-old male presented with a 5-month history of Published online 11 March 2004 fatigue, fever, night sweat and 20 kg weight loss. He was found to have splenomegaly, anemia and leukocytosis of 30 Â 109/l with TO THE EDITOR 16% . aspirate and biopsy performed elsewhere were reported as being consistent with a myeloproli- Imatinib mesylate produces complete hematologic and cytoge- ferative disorder. Stool and blood tests were negative for bacterial netic remissions in chronic myeloid leukemia (CML) by or parasitic infection. Electrocardiogram and echocardiogram effectively inhibiting the resident BCR/ABL oncoprotein.1 More were normal and there was no evidence of end-organ disease. recently, the drug was also shown to be active in eosinophilic Subsequent follow-up demonstrated progressive splenomegaly and disorders in the absence of the bcr/abl mutation.2,3 (6 cm below the left costal margin) and worsening anemia The drug target in the latter disorders was subsequently (hemoglobin was 7.7 g/dl) with a dramatic peripheral leukocy- discovered to be an activating mutation of the -derived 9 tosis to 140 Â 10 /l with 14% eosinophils and 2% blasts. He was growth factor receptor-a gene (FIP1L1-PDGFRA).4,5 In the managed elsewhere with transfusions and a prolonged course of current case report, we demonstrate a morphologic as well as hydroxyurea therapy at 3 g/day. Allogeneic bone marrow immunophenotypic normalization of bone marrow mast cells in transplantation was considered, but typing of his seven siblings a patient with eosinophilia-associated systemic mastocytosis failed to identify a donor. Profound hydroxyurea-induced treated with imatinib mesylate. pancytopenia led to transfer to our institution. Bone marrow biopsy at our institution led to the diagnosis of systemic mastocytosis with associated eosinophilia. The BM was markedly Correspondence: Dr A Tefferi, Mayo Clinic, 200 First Street, hypercellular (95% cellularity) with aggregates of atypical mast SW, Rochester, MN 55905, USA; Fax: + 507 266 4972; E-mail: [email protected] cell infiltrates (15% involvement) associated with intense Received 27 May 2003; accepted 28 January 2004; Published online eosinophilia, monocytosis and left-shifted granulopoiesis 11 March 2004 (Figure 1a). Immunohistochemical staining demonstrated

Leukemia Correspondence 1028

Figure 1 Bone marrow histology before (a) and after (b) treatment with imatinib mesylate showed marked improvement and was accompanied by a corresponding mast cell immunophenotypic remission (c, d).

aggregates of c-Kit (CD117)-and tryptase-positive atypical After failing an initial treatment trial with interferon-a,a mast cells in a perivascular location. Flow cytometry revealed therapeutic trial with imatinib mesylate at the dose of 400 mg/ that the bone marrow mast cells coexpressed CD117 and CD25 day was initiated based on our previous successful experience but not CD2 (Figure 1c). Bone marrow cytogenetic studies and with the treatment of bcr/abl-negative hypereosinophilic syn- fluorescent in situ hybridization (FISH) for bcr/abl were negative. drome.2 Within 2 days, the leukocyte count decreased from PCR analysis for c-kit mutations (D816 V and V569G) were 69.8 Â 109 to 9.4 Â 109/l and the platelet count remained negative. stable at 31 Â 109/l. After 5 days, the leukocyte count was at

Leukemia Correspondence 1029 3.2 Â 109/l with an absolute count of 1670, an MA Elliott1 1Mayo Clinic, Rochester, MN, USA 1 absolute count (AEC) of below 0.1 Â 109/l, and a A Pardanani CY Li1 stable platelet count. The dose of imatinib was reduced to 1 100 mg daily after 1 week of therapy. Within 4, 5 and 6 weeks, A Tefferi the platelet, neutrophil and hemoglobin normalized, respec- tively, and the patient achieved complete clinical remission. A bone marrow biopsy after 3 months of imatinib therapy revealed References normal histology (Figure 1b) and a marked reduction (from 15% involvement to minimal evidence of morphologically abnormal 1 Druker BJ, Talpaz M, Resta DJ, Peng B, Buchdunger E, Ford JM et al. mast cells) in the previously dominant aberrant CD25-positive Efficacy and safety of a specific inhibitor of the BCR-ABL tyrosine mast cell population (Figure 1d). The AEC at that point was kinase in chronic myeloid leukemia. N Engl J Med 2001; 344: below 0.2 Â 109/l. The patient remains in complete remission at 1031–1037. 2 Gleich GJ, Leiferman KM, Pardanani A, Tefferi A, Butterfield JH. last follow-up (19 months) and laboratory studies on archival Treatment of hypereosinophilic syndrome with imatinib mesilate. tissue confirmed the presence of the FIP1-PDGFRA oncogenic Lancet 2002; 359: 1577–1578. mutation that is targeted by imatinib mesylate.4 3 Pardanani A, Elliott M, Reeder T, Li C-Y, Baxter EJ, Cross NCP et al. The current communication is the first to describe immuno- Imatinib for systemic mast-cell disease. Lancet 2003; 362: 535–536. phenotypic normalization of bone marrow mast cells in patients 4 Cools J, DeAngelo DJ, Gotlib J, Stover EH, Legare RD, Cortes J et al. with systemic mastocytosis treated with imatinib mesylate. It is A tyrosine kinase created by fusion of the PDGFRA and FIP1L1 genes as a therapeutic target of imatinib in idiopathic hypereosino- to be recalled that neoplastic mast cells are both morphologi- philic syndrome. N Engl J Med 2003; 348: 1201–1214. cally (spindle-shaped and hypogranular vs round with abundant 5 Pardanani A, Ketterling RP, Brockman SR, Flynn HC, Paternoster SF, cytoplasmic granules) and immunophenotypically (CD117 þ / Shearer BM et al. CHIC2 deletion, a surrogate for FIP1L1-PDGFRA CD25 þ vs CD117 þ /CD25À) different from their normal as well fusion, occurs in systemic mastocytosis associated with eosinophilia as reactive counterparts.6 The current case demonstrates the and predicts response to imatinib therapy. Blood 2003; 102: 3093–3096. value of bone marrow histology enhanced with tryptase or 6 Pardanani A, Kimlinger TK, Reeder TL, Li CY, Tefferi A. Differential CD117-based immunohistochemistry as well as bone marrow expression of CD2 on neoplastic mast cells in patients with systemic mast cell immunophenotyping in the monitoring of effective mast cell disease with and without an associated clonal haemato- therapy in systemic mastocytosis. logical disorder. Br J Haematol 2003; 120: 691–694.

Novel chromosomal aberrations in Philadelphia negative cells of chronic myelogenous leukemia patients on imatinib: report of three cases

Leukemia (2004) 18, 1029–1031. doi:10.1038/sj.leu.2403345 Case 1 Published online 18 March 2004 A 22-year-old male was diagnosed with CML in accelerated TO THE EDITOR phase in December 2001. Cytogenetic analysis of bone marrow (BM) mononuclear cells revealed t(9;22) (q34;q11) in all The emergence of novel chromosomal aberrations in Ph (À) metaphases tested. RT-PCR identified b3a2 chimeric BCR-ABL cells of chronic myelogenous leukemia (CML) patients treated mRNA transcripts. The patient was initially given hydroxyurea; with interferon-alpha (IFN-alpha) is a rare event; a recent review starting from March 2002, he was put on imatinib at 400 mg/ of the literature identified 10 such cases.1–2 day. At 6 months on imatinib, he had attained complete In most CML patients, treatment with imatinib mesylate hematological remission and a minimal cytogenetic response (Glivec), a specific ABL kinase inhibitor, leads to disappearance with 96% Ph( þ ) metaphases. Imatinib dose was then increased of the Ph chromosome; nevertheless, the long-term efficacy and to 600 mg/day; at 14 months, cytogenetic analysis demonstrated toxicity profile of imatinib remain largely unknown. Intriguingly, major cytogenetic response (25.9% (7/27) Ph ( þ ) metaphases) over the last 2 years, several groups have demonstrated Ph (À) concurrently with the appearance of a novel hypodiploid clone cytogenetically abnormal clones in patients with CML treated with monosomy 7 in 8/27 metaphases, all Ph (À); interestingly, with imatinib, at a rate seemingly higher than the one observed there was also a Ph (À) metaphase with trisomy 8. FISH analysis with IFN-alpha.2–8 confirmed isolated trisomy 8 and monosomy 7 in 6.5 and 29% In our department, in a cohort of 35 CML patients treated with of cells, respectively. Examination of BM aspirate and biopsy imatinib for a median duration of 16.0 months (range, 3–42 samples showed no evidence of myelodysplasia. The patient months), three patients developed novel chromosomal aberra- underwent allogeneic matched sibling hematopoietic cell tions in Ph (À) cells as reported below. transplantation in July 2003; he remains in complete hemato- logical, cytogenetic and molecular remission.

Correspondence: A Athanasiadou, Hematology Department and Case 2 HCT Unit, G Papanicolaou Hospital, 57010 Thessaloniki, Greece; Fax: 00 30 2310 350521; E-mail: [email protected] Received 8 January 2004; accepted 9 February 2004; Published A 43-year-old female subject was diagnosed with CML in online 18 March 2004 myeloid blast crisis (10% MPO þ CD34 þ BM blast cells;

Leukemia