The prognostic significance of FLT3 mutations in acute promyelocytic leukemia (APL) is not firmly established and is of particular interest given the opportunities for targeted therapies using FLT3 inhibitors. We studied 203 patients with PML-RARA-positive APL; 43% of the patients had an FLT3 mutation (65 internal tandem duplications [ITDs], 19 D835/I836, 4 ITD؉D835/I836). Both mutations were associated with higher white blood cell (WBC) count at presentation; 75% of the patients with WBC counts of 10 ؋ 10 9 /L or greater had mutant FLT3. FLT3/ITDs were correlated with M3v subtype (P < .001), bcr3 PML breakpoint (P < .001), and expression of reciprocal RARA-PML transcripts (P ‫؍‬ .01). Microarray analysis revealed differences in expression profiles among patients with FLT3/ITD, D835/I836, and wild-type FLT3. Patients with mutant FLT3 had a higher rate of induction death (19% vs 9%; P ‫؍‬ .04, but no significant difference in relapse risk (28% vs 23%; P ‫؍‬ .5) or overall survival (59% vs 67%; P ‫؍‬ .2) at 5 years. In in vitro differentiation assays using primary APL blasts (n ‫؍‬ 6), the FLT3 inhibitor CEP-701 had a greater effect on cell survival/proliferation in FLT3/ITD ؉ cells, but this inhibition was reduced in the presence of ATRA. IntroductionMost cases of acute promyelocytic leukemia (APL) are characterized by t(15;17)(q22;q21) leading to formation of the promyelocytic leukemia-retinoic acid receptor ␣ (PML-RARA) fusion protein. 1 PML-RARA plays a critical role in determining disease phenotype, mediating the characteristic differentiation block through the repression of genes implicated in myelopoiesis, which is overcome by pharmacologic levels of retinoic acid. 1 However, evidence derived largely from transgenic mouse models has suggested that PML-RARA is insufficient for leukemogenesis, 2,3 although the precise nature of the cooperating events implicated in generating the full disease phenotype remains uncertain. A number of potential candidates have been proposed to play a role in this process. These include the reciprocal fusion gene product RARA-PML, which is expressed in approximately 75% of patients [4][5][6] and has been postulated to contribute to leukemogenesis by promoting genomic instability, thereby predisposing to the acquisition of additional oncogenic lesions. 7 There has also been considerable interest in the potential role of activating mutations of genes encoding receptor tyrosine kinases (RTKs), which commonly accompany acute myelocytic leukemia (AML)-associated translocations including t(15;17), giving rise to the proposition that they could provide a common class of cooperating mutation in the development of the disease. 8 Fms-like tyrosine kinase 3 (FLT3) is an RTK expressed on hematopoietic progenitors. Mutation of the FLT3 gene is common in AML. [9][10][11][12] Numerous mutations have been identified. The majority, present in approximately 25% of patients, are internal tandem duplications (ITDs) that lead to in-frame insertions within the juxtamembrane region of the receptor. Le...

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Acute promyelocytic leukaemia (APL; AML M3) is identified by a unique t(15;17) translocation which fuses the PML gene to the retinoic acid receptor alpha gene (RARA). Reverse transcription coupled with the polymerase chain reaction (RT-PCR) has been used to develop a diagnostic test for APL based on the PML-RARA fusion message. Separate PCR assays were designed to amplify either PML-RARA (15q+ derived) or RARA-PML (17q- derived) chimaeric transcripts. PML-RARA transcripts were detected in every case from a series of 18 APL patients with cytogenetically confirmed t(15;17) translocations, whereas RARA-PML messages were detected in only 67% (12/18) of these patients. This suggests that it is the 15q+ derivative which mediates leukaemogenesis. Furthermore the PCR approach (or Southern analysis) may be used to identify in which of the alternative PML introns the breakpoint occurs; 52% of cases (15/29 patients) utilize a 5' PML intron and 48% the 3' intron (14/29 cases). Neither the choice of PML intron nor the expression of the 17q- derivative could be correlated with the microgranular variant of APL (M3V), overall survival rate, age, sex or presence of coagulopathy. Finally, the fusion message is undetectable in five remission samples. This indicates a possible use for RT-PCR in monitoring remission patients for evidence of relapse.

Thirty patients with the 8;21 translocation and three with closely related variants have been studied. Ages ranged from 3 to 64 years (mean 28.3). Thirty-one were entered into the MRC's 8th Acute Myeloid Leukaemia Trial. Twenty-nine (88%) achieved complete remission. Marrow smears from most patients showed granulocytic maturation (M2, FAB classification) with characteristic abnormalities, but at least six showed predominantly myeloblastic (M1) morphology. The blast cells were markedly heterogeneous with regard to size and nuclear cytoplasmic ratio. Typical staining patterns were observed in the blast cells using Sudan black B and diaminobenzidine peroxidase stains, and to a lesser extent with periodic acid-Schiff and chloroacetate esterase. Butyrate esterase was negative in all cases. Auer rods were present in the granulocyte precursors in 31 cases and in eosinophil precursors in two cases. In most cases the existence of the translocation was predicted from the cytological and cytochemical findings. Seven patients developed solid leukaemic deposits, principally in the mastoid cavities, orbital cavities or thoracic spine (extradural).

The xeroderma pigmentosum group D (XPD) gene encodes a DNA helicase that functions in nucleotide excision repair of chemotherapy-induced DNA damage, the efficiency of which is predicted to be affected by a lysine to glutamine variant at codon 751. We hypothesized that this constitutive genetic variant may modify clinical response to chemotherapy, and we have examined its association with outcome following chemotherapy for acute myeloid leukemia (AML) in 341 elderly patients entered into the United Kingdom Medical Research Council AML 11 trial, and with the risk of developing chemotherapy-related AML. Among subjects treated for AML, disease-free survival at one year was 44% for lysine homozygotes, compared with 36% for heterozygotes and 16% for glutamine homozygotes (hazard ratio [HR], 1.30; 95% confidence interval [CI], 1.01-1.70; P ‫؍‬ .04). Similarly, overall survival at one year was 38% for lysine homozygotes, 35% for heterozygotes, and 23% for glutamine homozygotes (HR, 1.18; 95% CI, 0.99-1.41; P ‫؍‬ .07). Furthermore, homozygosity for the XPD codon 751 glutamine variant was associated with a significantly increased risk of developing AML after chemotherapy (odds ratio, 2.22 for Gln/Gln vs Lys/Lys; 95% CI, 1.04-4.74). These data suggest that the XPD codon 751 glutamine variant protects against myeloid cell death after chemotherapy. IntroductionThe affect of somatic alterations in genes such as RAS, FLT3, and P53 on the prognosis of acute myeloid leukemia (AML) has been well documented. [1][2][3][4] In contrast, relatively little is known about how constitutive genetic variation may influence the response of either leukemic or normal myeloid cells to chemotherapy. Recent efforts have identified polymorphisms in chemotherapy-metabolizing genes, including the glutathione S-transferase genes, which modulate AML prognosis after chemotherapy and also the etiology of chemotherapy-related AML. 5,6 Genetic variation in other pathways that mediate cellular response to chemotherapy, such as DNA repair, may also modulate prognosis and etiology of AML after chemotherapy.Nucleotide excision DNA repair (NER) protects against mutagenicity and toxicity by removing deleterious DNA lesions from the genome, including those induced by nitrogen mustards and several other classes of chemotherapy. [7][8][9][10] The chemotherapeutic nitrogen mustards, including melphalan and cyclophosphamide, are not only used in the treatment of AML, 11,12 but are also suspected myeloid leukemogens. 13 As such, constitutive variation in NER activity is predicted to affect how leukemic and normal myeloid cells respond to mustard-based therapies.The xeroderma pigmentosum group B (XPB) and group D (XPD) genes encode DNA helicases that mediate DNA unwinding required for initiation of both NER and basal transcription. 14 Such is the complexity of their roles in cellular function that rare constitutive mutations in XPB and XPD can give rise to 3 distinct human disorders: xeroderma pigmentosum, Cockayne syndrome, and trichothiodystrophy, 14-15 all of whi...

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Summary. Acute myeloid leukaemia (AML) with the t(8;21)(q22;q22) is deemed to be a 'good-risk' disease. 396 patients with AML at diagnosis were screened for the presence of t(8;21) and AML1/ETO fusion transcripts by cytogenetic and RT-PCR techniques respectively. 32 cases of t(8;21) were detected, all of which were also PCR positive. A further 19 cases were detected at the molecular level, predominantly but not exclusively in M1 and M2 FAB types. Approximately 12% of all new cases of AML are estimated to have AML1/ETO fusion transcripts and it is suggested that molecular screening should be performed in all cases with the possible exception of the M3 FAB type.

115 patients with acute promyelocytic leukaemia (APL) were studied retrospectively to evaluate prognostic factors and assess therapeutic approaches, particularly the use of heparin in the management of disseminated intravascular coagulation (DIC). The remission rate was 86% (30/35 patients) in those who received heparin and 49% (39/80 patients) in those who received no heparin (P = 0.0002). This difference in remission rates was accounted for by a marked decrease in the number of haemorrhagic deaths, especially those due to intracranial haemorrhage (ICH), in the heparin treated group. Other factors associated with a poor remission rate were prothrombin ratio (PTR) greater than 1.3 (P = 0.008), fibrinogen less than 1.5 g/l (P = 0.02) and WCC greater than 2.0 x 10(9)/l (P = 0.03).