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PubMed2006

Curcumin affects components of the chromosomal passenger complex and induces mitotic catastrophe in apoptosis-resistant Bcr-Abl-expressing cells.

The Bcr-Abl oncoprotein plays a major role in the development and progression of chronic myeloid leukemia and is a determinant of chemotherapy resistance occurring during the blast crisis phase of the disease. The aim of this article was to investigate the possibility of combating the resistance to apoptosis caused by Bcr-Abl by inducing an alternative cell death process. As a model of chronic myeloid leukemia, we employed Bcr-Abl-transfected mouse progenitor 32D cells with low and high Bcr-Abl expression levels corresponding to drug-sensitive and drug-resistant cells, respectively. The drug curcumin (diferuloylmethane), a known potent inducer of cell death in many cancer cells, was investigated for efficacy with Bcr-Abl-expressing cells. Curcumin strongly inhibited cell proliferation and affected cell viability by inducing apoptotic symptoms in all tested cells; however, apoptosis was a relatively late event. G(2)-M cell cycle arrest, together with increased mitotic index and cellular and nuclear morphology resembling those described for mitotic catastrophe, was observed and preceded caspase-3 activation and DNA fragmentation. Mitosis-arrested cells displayed abnormal chromatin organization, multipolar chromosome segregation, aberrant cytokinesis, and multinucleated cells-morphologic changes typical of mitotic catastrophe. We found that the mitotic cell death symptoms correlated with attenuated expression of survivin, a member of the chromosomal passenger complex, and mislocalization of Aurora B, the partner of survivin in the chromosomal passenger complex. Inhibition of survivin expression with small interfering RNA exhibited similar mitotic disturbances, thus implicating survivin as a major, albeit not the only, target for curcumin action. This study shows that curcumin can overcome the broad resistance to cell death caused by expression of Bcr-Abl and suggests that curcumin may be a promising agent for new combination regimens for drug-resistant chronic myeloid leukemia.

Animals↗
PubMed2001

[Selective inhibition of tyrosine kinases - a new therapeutic principle in oncology].

Tyrosine kinases are enzymes that regulate mitosis, differentiation, migration, neovascularization, and apoptosis. Their spectrum and association with specific malignancies offer multiple targets for therapeutic intervention. Chronic myelogenous leukemia (CML) represents an ideal target for a therapy using a selective inhibitor of the BCR-ABL tyrosine kinase. The 2-phenylpyrimidine derivative STI571 was rationally designed to inhibit ABL and BCR-ABL tyrosine kinase activities through competitive ATP-binding pocket interactions. Phase II data demonstrate hematologic and cytogenetic responses in interferon refractory chronic-phase, accelerated-phase and blast crisis patients. However, long-term observation is needed to confirm that response data result in prolongation of survival. STI571 is being studied in other malignancies, including leukemias characterized by expression of alternate molecular forms of BCR-ABL and those expressing protein tyrosine kinases with ATP-binding pockets structurally similar to ABL, e.g. c-kit and PDGF-R. Gastrointestinal stromal tumor (GIST) cells overexpress the stem cell factor receptor CD117, the product of the proto-oncogene c-kit. Inhibition of c-kit in vivo results in an immediate metabolic change of the tumor cells, detectable by positron emission tomography. Since c-kit overexpression is inhibited in small-cell lung cancer cell lines, a study with STI571 as second-line therapy of c-kit-positive small-cell lung cancer is in progress. Clinical studies are ongoing in malignancies associated with an enhanced activity of the PDGF-R, such as highgrade glioma, prostate cancer and leukemias with rearrangements of PDGF-R. The development of selective tyrosine kinase inhibitors is considered a promising approach for the design of new drugs. Clinical responses to STI571 in various malignancies may stimulate greater interest in the clinical use of tyrosine kinase inhibitors.

Antineoplastic Agents↗
PubMed1993

Subcellular localization of Bcr, Abl, and Bcr-Abl proteins in normal and leukemic cells and correlation of expression with myeloid differentiation.

We used specific antisera and immunohistochemical methods to investigate the subcellular localization and expression of Bcr, Abl, and Bcr-Abl proteins in leukemic cell lines and in fresh human leukemic and normal samples at various stages of myeloid differentiation. Earlier studies of the subcellular localization of transfected murine type IV c-Abl protein in fibroblasts have shown that this molecule resides largely in the nucleus, whereas transforming deletion variants are localized exclusively in the cytoplasm. Here, we demonstrate that the murine type IV c-Abl protein is also found in the nucleus when overexpressed in a mouse hematopoietic cell line. However, in both normal and leukemic human hematopoietic cells, c-Abl is discerned predominantly in the cytoplasm, with nuclear staining present, albeit at a lower level. In contrast, normal endogenous Bcr protein, as well as the aberrant p210BCR-ABL and p190BCR-ABL proteins consistently localize to the cytoplasm in both cell lines and fresh cells. The results with p210BCR-ABL were confirmed in a unique Ph1-positive chronic myelogenous leukemia (CML) cell line, KBM5, which lacks the normal chromosome 9 and hence the normal c-Abl product. Because the p210BCR-ABL protein appears cytoplasmic in both chronic phase and blast crisis CML cells, as does the p190BCR-ABL in Ph1-positive acute leukemia, a change in subcellular location of Bcr-Abl proteins between cytoplasm and nucleus cannot explain the different spectrum of leukemias associated with p210 and p190, nor the transition from the chronic to the acute leukemia phenotype seen in CML. Further analysis of fresh CML and normal hematopoietic bone marrow cells reveals that p210BCR-ABL, as well as the normal Bcr and Abl proteins, are expressed primarily in the early stages of myeloid maturation, and that levels of expression are reduced significantly as the cells mature to polymorphonuclear leukocytes. Similarly, a decrease in Bcr and Abl levels occurs in HL-60 cells induced by DMSO to undergo granulocytic differentiation. The action of p210BCR-ABL and its normal counterparts may, therefore, take place during the earlier stages of myeloid development.

Animals↗
PubMed2002

The effects of Bcr-Abl on C/EBP transcription-factor regulation and neutrophilic differentiation are reversed by the Abl kinase inhibitor imatinib mesylate.

The clinical progression of chronic myeloid leukemia (CML) from chronic phase to blast crisis is characterized by the increasing failure of myeloid precursors to differentiate into mature granulocytes. This study was undertaken to investigate the influence of Bcr-Abl and of the small molecule Abl tyrosine-kinase inhibitor imatinib mesylate on granulocyte colony-stimulating factor (G-CSF)-induced neutrophilic differentiation. We show that differentiation of 32Dcl3 cells into mature granulocytes is accompanied by the increased expression of the antigens macrophage adhesion molecule-1 (Mac-1) and Gr-1, of the G-CSF receptor (G-CSFR), of myeloid transcription factors (CCAAT/enhancer-binding protein-alpha [C/EBPalpha], C/EBPepsilon, and PU.1), and of the cyclin-dependent kinase inhibitor p27(Kip1). In 32Dcl3 cells transfected with the bcr-abl gene (32D(Bcr-Abl)), G-CSF did not trigger either granulocytic differentiation or the up-regulation of C/EBPalpha, C/EBPepsilon, and the G-CSFR. This could be correlated to a defect in c-Myc down-regulation. In contrast, the up-regulation of PU.1 and p27(Kip1) by G-CSF was not affected by Bcr-Abl. Importantly, incubation of 32D(Bcr-Ablwt) cells with the kinase inhibitor imatinib mesylate prior to G-CSF stimulation completely neutralized the effects of Bcr-Abl on granulocytic differentiation and on C/EBPalpha and C/EBPepsilon expression. Taken together, the results suggest that the Bcr-Abl kinase induces a reversible block of the granulocytic differentiation program in myeloid cells by disturbing regulation of hematopoietic transcription factors such as C/EBPalpha and C/EBPepsilon.

Animals↗
PubMed2003

BCR/ABL alters the function of NK cells and the acquisition of killer immunoglobulin-like receptors (KIRs).

Natural killer (NK) cells decrease in function during chronic myelogenous leukemia (CML) progression from chronic phase to blast crisis, and they can become BCR/ABL(+) late in the disease course. To study this altered function, NK92 cells were transduced with the BCR/ABL oncogene. In contrast to the parental cells, which died when deprived of interleukin 2 (IL-2), p210(+) NK92 cells proliferated and survived indefinitely in the absence of IL-2. BCR/ABL also decreased the natural cytotoxicity of NK92 cells against K562 targets, without affecting IL-2, interferon gamma (IFN-gamma), or tumor necrosis factor alpha (TNF-alpha) production. Although the ABL-specific tyrosine kinase inhibitor imatinib mesylate (STI-571) had no effect on parental NK92 cells, it markedly decreased the growth and survival of IL-2-independent p210(+) NK92 cells. In contrast to the parental cell line, serial analysis of p210(+) NK92 cells detected small populations that clonally expressed one or more killer immunoglobulin-like receptors (KIRs). Unlike the decreased natural cytotoxicity, the function of the activating CD158j receptor remained intact. Southern blotting and hybridization with an enhanced green fluorescence protein (eGFP) probe showed that KIR(-) and KIR(+) NK92 cells were all derived from the same clone, suggesting that KIR acquisition remains dynamic at the maturational stage represented by the NK92 cell line. When tested in primary CD56(+bright) NK cells, p210 induced partial IL-2-independent growth and increased KIR expression similar to findings in NK92 cells. This is the first study to show that BCR/ABL, well known for its effects on the myeloid lineage, can alter the function of lymphoid cells, which may be associated with the defect in innate immunity associated with CML progression.

Benzamides↗
PubMed2005

Adaphostin-induced oxidative stress overcomes BCR/ABL mutation-dependent and -independent imatinib resistance.

The BCR/ABL kinase has been targeted for the treatment of chronic myelogenous leukemia (CML) by imatinib mesylate. While imatinib has been extremely effective for chronic phase CML, blast crisis CML and Ph+ acute lymphoblastic leukemia (ALL) are often resistant. In particular, mutation of the T315 residue in the bcr/abl activation loop renders cells highly resistant to imatinib and to second-generation kinase inhibitors such as BMS-354825 or AMN107. Adaphostin is a tyrphostin that was originally intended to inhibit the BCR/ABL kinase by competing with its peptide substrates. Recent findings have in addition implicated reactive oxygen species (ROS) in the cytotoxic mechanism of adaphostin. In view of this unique mode of action, we examined the effects of adaphostin on numerous imatinib-resistant leukemia models, including imatinib-resistant CML and Ph+ ALL cell lines, cells harboring point mutations in BCR/ABL, and specimens from imatinib-resistant CML patients, using assays for intracellular ROS, apoptosis, and clonogenicity. Every model of imatinib resistance examined remained fully sensitive to adaphostin-induced cell death. Collectively, these data suggest that ROS generation by adaphostin overcomes even the most potent imatinib resistance in CML and Ph+ ALL.

Adamantane↗
PubMed2006

Leukemogenesis induced by wild-type and STI571-resistant BCR/ABL is potently suppressed by C/EBPalpha.

Chronic phase-to-blast crisis transition in chronic myelogenous leukemia (CML) is associated with differentiation arrest and down-regulation of C/EBPalpha, a transcription factor essential for granulocyte differentiation. Patients with CML in blast crisis (CML-BC) became rapidly resistant to therapy with the breakpoint cluster region-Abelson murine leukemia (BCR/ABL) kinase inhibitor imatinib (STI571) because of mutations in the kinase domain that interfere with drug binding. We show here that the restoration of C/EBPalpha activity in STI571-sensitive or -resistant 32D-BCR/ABL cells induced granulocyte differentiation, inhibited proliferation in vitro and in mice, and suppressed leukemogenesis. Moreover, activation of C/EBPalpha eradicated leukemia in 4 of 10 and in 6 of 7 mice injected with STI571-sensitive or -resistant 32D-BCR/ABL cells, respectively. Differentiation induction and proliferation inhibition were required for optimal suppression of leukemogenesis, as indicated by the effects of p42 C/EBPalpha, which were more potent than those of K298E C/EBPalpha, a mutant defective in DNA binding and transcription activation that failed to induce granulocyte differentiation. Activation of C/EBPalpha in blast cells from 4 patients with CML-BC, including one resistant to STI571 and BMS-354825 and carrying the T315I Abl kinase domain mutation, also induced granulocyte differentiation. Thus, these data indicate that C/EBPalpha has potent antileukemia effects even in cells resistant to ATP-binding competitive tyrosine kinase inhibitors, and they portend the development of anti-leukemia therapies that rely on C/EBPalpha activation.

Animals↗
PubMed2001

Restoration of sensitivity to STI571 in STI571-resistant chronic myeloid leukemia cells.

STI571 induces sustained hematologic remission in patients with chronic myeloid leukemia (CML) in chronic phase. However, in advanced phases, especially blast crisis, the leukemia usually becomes resistant within months. It has been investigated whether resistance to STI571 is stable and immutable or whether it can be reversed in selected CML cell lines. Withdrawal of STI571 for varying lengths of time from cultures of 3 resistant lines (K562-r, KCL22-r, and Baf/BCR-ABL-r1) did not restore sensitivity to the inhibitor. In contrast, LAMA84-resistant cells experienced a sharp reduction in survival and proliferation during the first week of STI571 withdrawal but recovered thereafter. Moreover, when left off the inhibitor for 2 months or longer, this cell line reacquired sensitivity to STI571. It is hypothesized, therefore, that patients who have become resistant to the drug may respond again if STI571 therapy is temporarily interrupted.

Animals↗
PubMed2003

Tyrosine kinase inhibitor as a therapeutic drug for chronic myelogenous leukemia and gastrointestinal stromal tumor.

The Philadelphia chromosome found in leukemia cells of chronic myelogenous leukemia (CML) patients is produced by translocation between chromosomes 9 and 22, resulting in expression of a chimera protein of Bcr and Abl kinase in the cytoplasm. Bcr-Abl kinase attracted oncology researchers as a molecular target for CML therapy, and a variety of small Abl kinase inhibitors were synthesized. STI571 (imatinib mesylate) was produced by modification of 2-phenylaminopyrimidine, a core structure of protein kinase C inhibitor, to improve selectivity, stability, solubility, and bioavailability. STI571 competitively binds to the ATP binding site of Bcr-Abl kinase and inhibits Abl tyrosine kinase activity. STI571 showed significant efficacy in the clinical study with CML patients at all stages: chronic phase, accelerated phase, and blast crisis. More than 90% of the patients showed good hematologic response to STI571. STI571 is also a potent inhibitor of a receptor-type c-Kit tyrosine kinase. Therefore, STI571 was examined for therapeutic efficacy against malignant Gastro-Intestinal Stromal Tumors (GIST), which are mainly caused by aberrant expression of a mutated c-Kit that is constitutively active without binding of a ligand, stem cell factor (SCF). More than a half of the metastatic GIST patients enrolled in the clinical study responded to STI571. Thus, STI571 is now used as a therapeutic drug for both CML and GIST in more than 80 countries worldwide. Certain point mutations in the ATP binding site were found to be a cause of resistance to STI571 in both Bcr-Abl and c-Kit kinases. Therefore, it would be better to make a precise therapeutic strategy with STI571 based on the gene analysis data. It is also expected that it will be possible to design an inhibitor to overcome such resistance by using the structural information on the mutants.

Antineoplastic Agents↗
PubMed2006

Coexistence of inversion 16 and the Philadelphia chromosome in acute and chronic myeloid leukemias : report of six cases and review of literature.

We report 5 cases of chronic myelogenous leukemia (CML) and 1 case of acute myeloid leukemia (AML) with the dual presence of t(9;22) and inv(16). The 6 patients were 5 men and 1 woman with a median age of 42.5 years. All cases were BCR-ABL+ with p210 products detected in all CML cases and a p190 product detected in the AML case. An increase in bone marrow eosinophils was detected in 3 of 5 cases, and abnormal eosinophils were identified in these 3 cases. The CBFbeta-MYH11 fusion gene was confirmed in all 3 CML cases and the 1 AML case tested, and this correlated with the presence of abnormal eosinophils with coarse basophilic granules. Of 5 patients with CML, 4 had a rapid transformation to myeloid accelerated phase of blast crisis. The coexistence of t(9;22) and inv(16) in CML seems to correlate with more rapid transformation.

Adult↗
PubMed1992

Molecular mechanisms in the evolution of chronic myelocytic leukemia.

Chronic myelocytic or Ph1-positive acute lymphoblastic leukemias have been analyzed for alterations in a variety of proto-oncogenes and anti-oncogenes implicated in the progression of chronic myeloid leukemia (CML) from its chronic phase to blast crisis. The most frequent genetic change found in disease evolution is an alteration of the p53 gene involving a point mutation, a rearrangement or a deletion. These gene changes are common in myeloid and undifferentiated variants of blast crisis but are usually undetectable in lymphoid leukemic transformants. Other molecular changes also occur in the clonal evolution of CML. The retinoblastoma-susceptibility (Rb) gene is an anti-oncogene. Structural abnormalities of Rb are frequent in all types of human acute leukemia, but are particularly common in Ph1-positive leukemia of lymphoid phenotype including both Ph1-positive ALL and lymphoid blast crisis of CML. Changes in Rb occur early in the transition to blast crisis with loss of Rb protein being the common factor. Mutations in the N-RAS gene also occur, but are rare in typical blast crisis. They are sometimes seen in Ph1-negative myeloid blast crisis. Since changes in the p53 gene are generally associated with progression of disease of a myeloid phenotype and changes in the Rb gene occur more often with a lymphoid phenotype, a particular molecular alteration may influence the character of disease evolution in CML.

Blast Crisis↗
PubMed1997

The role of autologous natural killer cells in chronic myelogenous leukemia.

Chronic myelogenous leukemia (CML) is a lethal disease of the hematopoietic stem cell. Bone marrow transplantation has highlighted the importance of allogeneic disparity in maintaining remissions in CML. However, it has been unclear whether the immune effect against CML is mediated by T cells, natural killer cells (NK) or a combination of both. We have previously demonstrated that autologous activated NK are capable of selectively lysing malignant CML progenitors while sparing benign progenitors. NK effectors may play an important role in CML since NK lytic function, clonogenic frequency and proliferative capacity decrease as CML progresses from chronic phase to advanced phase and blast crisis. Incubation of CML NK with IL-2 is capable of restoring cytolytic activity to normal levels. We hypothesize that activated NK represent a potential therapy against CML to maintain remissions in a minimal residual disease setting induced by autologous transplantation. Clinical trials are in progress to test whether IL-2 based immunotherapy and activated cell infusions play a therapeutic role in CML.

Disease Progression↗
PubMed2006

Proliferation studies on chromosome preparations of bone marrow in hematological disease.

The growth rate of neoplastic cells has been the subject of numerous scientific and diagnostic approaches. The study presented here analyses the relationship between mitotic activity in standardised cytogenetic bone marrow preparations from three haematological diseases and diagnostic and clinical parameters, most importantly the outcome. The disorders studied were: Acute lymphoblastic leukemia (ALL) (N=107), chronic myeloid leukemia (CML) (N=166) and aplastic anemia in childhood (AA) (N=39). A strict protocol of quantitative standardisation of cytogenetic slides was adhered to ensuring comparability both cross-sectionally and longitudinally. The samples were studied after short-term incubation without mitogenic in vitro stimuli. The most important findings include: i) ALL: Immunological subtypes can be differentiated according to their proliferation profile; there is a striking difference between childhood and adult ALL in proliferation activity; most importantly initial proliferation is much higher in patients who will relapse than in those with stable remission. ii) CML: Philadelphia-positive CML shows proliferation activities quite distinct from Philadelphia-negative CML; however there is only a small change in the proliferative activity from the chronic phase to the accelerated phase or blast crisis. iii) AA: Very low proliferation scores rise quickly to near normal levels during immunosuppressive therapy in most patients. Higher levels at diagnosis are associated with a faster and better response to therapy. In conclusion, assessment of the proliferative activity in cytogenetic preparations made from bone marrow samples of patients with haematological disease may add valuable information as to diagnostic sub-groups and clinical course and may contribute to therapeutic decisions.

Adolescent↗
PubMed2005

BCR-ABL kinase domain mutations in chronic myeloid leukemia: not quite enough to cause resistance to imatinib therapy?

Patients with chronic myeloid leukemia (CML) treated with imatinib in early chronic phase tend to have durable remissions, but there is a high rate of relapse in patients with advanced disease. Mutations in the kinase domain of BCR-ABL that impair drug binding have been identified as the major mechanism of resistance. It is not known when exactly these mutations arise, but in some patients retrospective analysis of pretherapeutic samples demonstrated identical mutations, suggesting selection in the presence of drug. In the present study we have used a highly sensitive PCR assay to screen for kinase domain mutations in pretherapeutic samples from CML patients, irrespective of their subsequent response to imatinib. We find that kinase domain mutations are demonstrable in approximately 1/3 of patients with accelerated phase or blast crisis and that the presence of two copies of the Philadelphia chromosome is strongly correlated with mutation detection. Unexpectedly, kinase domain mutant clones were not invariably selected in the presence of drug, suggesting that additional mechanisms must contribute to a fully drug resistant leukemia.

Adult↗
PubMed2002

[Bcr-Abl inhibition as molecular therapy approach in chronic myeloid leukemia].

BACKGROUND: Bcr-Abl, a constitutively activated tyrosine kinase, is a product of the Philadelphia chromosome (Ph) translocation t(9;22), present in nearly all cases of chronic myeloid leukemia (CML) and in about 20% of cases with acute lymphoblastic leukemia. CML, a myeloproliferative disorder, progresses through three phases--chronic phase, accelerated phase and blast crisis. Current therapies include drug regimens such as interferon alpha, hydroxyurea, busulfan or allogeneic bone marrow transplantation, the only curative treatment for CML, which is, however, limited to younger patients with a suitable donor. INHIBITION OF BCR-ABL AS EFFECTIVE AND SELECTIVE TREATMENT IN CML: In vitro studies and studies in animal models have shown, that Bcr-Abl is the molecular cause CML. Therefore inhibition of the Bcr-Abl tyrosine kinase is expected to be an effective and selective treatment modality for CML. STI571 was shown to be a competitive inhibitor at the ATP-binding site of the Bcr-Abl tyrosine kinase, the platelet-derived growth factor receptor and c-kit tyrosine kinases. It shows effects on proliferation and survival of Bcr-Abl-expressing cells without affecting normal cells or Ph-negative leukemic cells. DRUG RESISTANCE TO STI571: Several mechanisms of resistance have been identified from in vitro studies with Bcr-Abl-positive cell lines. Mechanisms include amplification or overexpression of Bcr-Abl or an increased expression of P-gly-coprotein. In a mouse model the binding of STI571 to acidic alpha 1 glycoprotein (AAG) has been proposed to be involved in the development of STI571 resistance. Recent studies with clinical samples from resistant patients have shown that point mutations in the kinase domain of Bcr-Abl play a role in the development of resistance to STI571. CONCLUSIONS: STI571 is a promising example of a moleculary targeted therapy directed towards the molecular cause of CML. To maximize the therapeutic value and to avoid the induction of resistance, a combination of the drug with other chemotherapies should be considered. According to its pharmacological profile, STI571 could also be useful in the treatment of tumors with deregulated PDGF receptor or c-kit signaling, e.g., in chronic myelomonocytic leukemia with a t(5;12) chromosomal translocation or in cases with gastrointestinal stromal tumors (GIST). STI571 shows a new paradigm in the development of new targeted therapies for the treatment of malignant diseases.

Animals↗
PubMed2003

[Down-regulation of expression of vascular endothelial growth factor induced by arsenic trioxide in bone marrow cells of chronic myeloid leukemia].

To investigate the effect of arsenic trioxide (As(2)O(3)) on vascular endothelial growth factor (VEGF) expression in different courses of chronic myeloid leukemia (CML), VEGF level was measured with ELISA in the cultural supernatants of bone marrow mononuclear cells from CML patients. The results showed that supernatants of cultured bone marrow cells from 35 CML patients (20 chronic, 8 accelerated and 7 blast crisis phases) contained significantly higher VEGF levels (649.16 +/- 382.20 pg/ml, 560.27 +/- 409.14 pg/ml and 587.18 +/- 415.28 pg/ml, respectively) than that in 15 normal control samples (152.16 +/- 150.09 pg/ml; P < 0.01), but no significant differences were found in VEGF levels among different phases of CML. The bone marrow cells treated with As(2)O(3) (5 x 10(-6)mol/L) for 72 hours resulted in significant reduction of VEGF levels (down to 396.66 +/- 257.47 pg/ml, 363.42 +/- 239.85 pg/ml and 407.47 +/- 219.38 pg/ml, respectively) (P < 0.05). In conclusion, abnormal high expression of VEGF plays a role in the pathogenetic course of CML and it is probably an additional anticancer mechanism for As(2)O(3) to inhibit VEGF expression of leukemic cells.

Adolescent↗
PubMed2003

Imatinib: new indication. Chronic myeloid leukaemia, first-line option: favourable findings to be confirmed.

(1) For many years the reference first-line treatment for patients with chronic myeloid leukaemia who do not qualify for bone marrow transplantation was interferon alfa-2, possibly combined with cytarabine. (2) Imatinib, a tyrosine kinase inhibitor, was initially approved for second-line treatment of adults with chronic myeloid leukaemia and in the accelerated phase or blast crisis. This indication has now been extended to cover first-line treatment and children. (3) An unblinded trial in 1106 adults compared imatinib (400 mg/day by mouth) as a first-line treatment with the combination of interferon (5 MIU/m2/day) and cytarabine (20 mg/m2/day, 10 days a month) subcutaneously. After 18 months, imatinib significantly increased progression-free survival rate (92.1% versus 73.5%) and quality of survival, but not overall survival. (4) In the paediatric setting, there are follow-up data from only 17 children who received imatinib as a first- or second-line treatment. The results were similar to those obtained in adults. (5) In the only available trial in adults, the number of treatment withdrawals for adverse events was lower among patients taking imatinib. Fatigue and depression were the two serious adverse events reported more commonly by people taking interferon + cytarabine. (6) Imatinib is given by mouth, which is more convenient than subcutaneous route required for interferon + cytarabine. (7) In practice, pending a second comparative trial and further follow-up, imatinib seems a therapeutic advance in the first-line treatment of chronic myeloid leukaemia.

Adult↗