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Clonal cytogenetic aberrations of the Philadelphia chromosome (Ph) positive hematopoiesis have been associated with the natural evolution of chronic myeloid leukemia (CML) to advanced disease. Clonal aberrations of Ph negative metaphases have been described after treatment with interferon or imatinib. This study evaluates the effect of dasatinib on Ph positive clones with additional cytogenetic aberrations and the frequency of novel aberrations in Ph positive and negative metaphases. Seventy-one patients treated with dasatinib after imatinib failure for a median of nine months were evaluated. Novel aberrations within Ph positive and negative clones appeared in six and three patients, respectively.

Early allogeneic hematopoietic stem cell transplantation (HSCT) has been proposed as primary treatment modality for patients with chronic myeloid leukemia (CML). This concept has been challenged by transplantation mortality and improved drug therapy. In a randomized study, primary HSCT and best available drug treatment (IFN based) were compared in newly diagnosed chronic phase CML patients. Assignment to treatment strategy was by genetic randomization according to availability of a matched related donor. Evaluation followed the intention-to-treat principle. Six hundred and twenty one patients with chronic phase CML were stratified for eligibility for HSCT. Three hundred and fifty four patients (62% male; median age, 40 years; range, 11-59 years) were eligible and randomized. One hundred and thirty five patients (38%) had a matched related donor, of whom 123 (91%) received a transplant within a median of 10 months (range, 2-106 months) from diagnosis. Two hundred and nineteen patients (62%) had no related donor and received best available drug treatment. With an observation time up to 11.2 years (median, 8.9 years), survival was superior for patients with drug treatment (P = .049), superiority being most pronounced in low-risk patients (P = .032). The general recommendation of HSCT as first-line treatment option in chronic phase CML can no longer be maintained. It should be replaced by a trial with modern drug treatment first.

Gender-related aspects in chronic myeloid leukemia (CML) have not been studied well. We therefore analyzed 856 patients with Ph/BCR-ABL-positive CML from the German randomized CML-studies I (interferon alpha (IFN) vs hydroxyurea (HU) vs busulfan) and II (IFN+HU vs HU alone). The median observation time was 8.6 years. A total of 503 patients (59%) were male. Female patients were older (51 vs 46 years; P<0.0001), presented with lower hemoglobin (11.7 vs 12.5 g/dl; P<0.0001), higher platelet counts (459 vs 355 x 10(9)/l; P<0.0001), smaller spleen size (3 vs 4 cm below costal margin; P=0.0097), a lower rate of additional cytogenetic aberrations (9 vs 15%; P=0.018) and a less favorable risk profile (P=0.036). The transplantation rate was 14% for female (n=48) and 22% for male patients (n=113). Median survival was longer in female patients (58 vs 49 months; P=0.035) mainly attributable to better survival in the low- and intermediate-risk groups and, independent from risk groups, in the HU group. These results were confirmed by matched-pair analyses based on German population data (n=496, 59 vs 45 months; P=0.0006). This is the first analysis of gender aspects in CML using randomized trials. It demonstrates the relevance of analyses of gender differences in CML and in malignant disease at large.

Background: The advent of imatinib has considerably changed the treatment of chronic myeloid leukemia (CML). Early studies demonstrated high rates of hematologic and cytogenetic responses in all phases of the disease after limited observation periods., Methods: The authors evaluated long-term outcome, rates of response, and resistance in 300 patients with BCR-ABL-positive leukemias (CML in chronic phase after failure to respond to interferon-alpha [CP], n = 139; accelerated phase [AP], n = 80; myeloid blast crisis [BC], n = 76; lymphoid BC and Philadelphia chromosome-positive acute lymphoblastic leukemia, n = 5) who entered clinical trials with imatinib in a single center after an observation time of 4.5 years., Results: In CP, hematologic remission was achieved in 97% and major (MCR) and complete cytogenetic remission (CCR) in 61% and 49% of patients, respectively. The chance to achieve MCR was higher in patients commencing imatinib earlier in the course of CML. In AP, the median survival period after the start of imatinib was 44 months, and MCR and CCR were observed in 31% and 26% of patients, respectively. In myeloid BC, the median survival period after the start of imatinib and after diagnosis of BC was 6 and 9 months, respectively. Hematologic resistance occurred in 25%, 41%, and 92% of patients in CP, AP, and myeloid BC, respectively, and was associated with BCR-ABL mutations in 45% of patients and with clonal evolution in 58% of patients., Conclusions: The data emphasized the need for a prolonged follow-up of patients treated with imatinib to define the clinical potential of the drug and to establish methods to optimize therapy., ((c) 2005 American Cancer Society.)

We sought to determine dynamics of BCR-ABL mRNA expression levels in 139 patients with chronic myelogenous leukemia (CML) in early chronic phase, randomized to receive imatinib (n=69) or interferon (IFN)/Ara-C (n=70). The response was sequentially monitored by cytogenetics from bone marrow metaphases (n=803) and qualitative and quantitative RT-PCR from peripheral blood samples (n=1117). Complete cytogenetic response (CCR) was achieved in 60 (imatinib, 87%) vs 10 patients (IFN/Ara-C, 14%) after a median observation time of 24 months. Within the first year after CCR, best median ratio BCR-ABL/ABL was 0.087%, (imatinib, n=48) vs 0.27% (IFN/Ara-C, n=9, P=0.025). BCR-ABL was undetectable in 25 cases by real-time PCR, but in only four patients by nested PCR. Median best response in patients with relapse after CCR was 0.24% (n=3) as compared to 0.029% in patients with continuous remission (n=52, P=0.029). We conclude that (i) treatment with imatinib in newly diagnosed CML patients is associated with a rapid decrease of BCR-ABL transcript levels; (ii) nested PCR may reveal residual BCR-ABL transcripts in samples that are negative by real-time PCR; (iii) BCR-ABL transcript levels parallel cytogenetic response, and (iv) imatinib is superior to IFN/Ara-C in terms of the speed and degree of molecular responses, but residual disease is rarely eliminated.

A significant proportion of chronic myeloid leukemia (CML) patients achieve a major cytogenetic remission (MCR) to imatinib therapy after failing interferon (IFN) alpha-based protocols. We sought to determine levels of residual disease in patients with MCR using various molecular methods and to establish a relation between residual BCR-ABL transcript levels and rate of relapse in complete cytogenetic remission (CCR). Response was measured by conventional cytogenetic analysis, hypermetaphase and interphase fluorescence in situ hybridization (HM-FISH, IP-FISH) of bone marrow (BM) cells, qualitative nested and quantitative reverse transcriptase polymerase chain reaction (RT-PCR) for BCR-ABL transcripts. We investigated 323 peripheral blood (PB) and BM samples from 48 CML patients who achieved a complete (Ph+ 0%; n=41) or partial (Ph+ 1-34%; n=7) cytogenetic remission after 3-20 months of imatinib therapy. Prior to imatinib, 35 patients were in chronic phase (CP), eight in accelerated phase (AP), four in myeloid and one in lymphoid blast crisis. HM-FISH results correlated with ratios BCR-ABL/ABL in PB and BM. In patients with CCR, residual disease was detectable by HM-FISH (31%), IP-FISH (18%), and RT-PCR (100%). During follow-up, BCR-ABL became undetectable in two patients (one CP, one AP) by both nested and quantitative RT-PCR. CCR is ongoing in 30 evaluable patients, 11 patients have relapsed. At the time of best response, median ratios BCR-ABL/ABL were 2.1% (range 0.82-7.8) in patients with subsequent relapse and 0.075% (range 0-3.9) in patients with ongoing remission (P=0.0011). All 16 CP patients, who achieved ratios BCR-ABL/ABL <0.1% as best molecular response are in continuous remission, while 6/13 patients (46%) with ratios >/=0.1% have relapsed (P=0.0036). We conclude that: (i) in patients with CCR to imatinib, HM-FISH and RT-PCR usually reveal residual BCR-ABL+ cells; (ii) RT-PCR results derived from PB and BM are comparable in CP CML; and (iii) low levels of residual disease with ratios BCR-ABL/ABL &<0.1% are associated with continuous remission.

Telomeres are composed of TTAGGG repeats and associated proteins. In somatic cells, telomere repeats are lost with each cell division, eventually leading to genetic instability and cellular senescence. In previous studies, we described substantial and disease stage-specific telomere shortening in peripheral blood (PB) leukocytes from patients with chronic myeloid leukemia (CML). Here, we sought to determine whether age-adjusted telomere length in PB granulocytes (deltaTEL(gran)) is associated with response to treatment with the selective tyrosine kinase inhibitor imatinib. A total of 517 samples from 206 patients in chronic phase (CP), accelerated phase (AP), and blast crisis (BC) before and up to 706 days after initiation of imatinib therapy (median: 144 days) were analyzed by quantitative fluorescence in situ hybridization of interphase cells in suspension (Flow-FISH); telomere fluorescence was expressed in molecular equivalents of soluble fluorochrome units (MESF). Telomere length in samples from start of treatment up to day 144 was significantly shorter (mean +/- SE; -1.5 +/- 0.3 kMESF) compared to samples from patients treated for more than 144 days (-0.8 +/- 0.3 kMESF, p = 0.035). In patients with repeated measurements, a significant increase in telomere length under treatment was observed. Median telomere length in major remission was found to be significantly longer compared to patients without response to treatment measured either by cytogenetics (n = 246, p < 0.05), interphase FISH (n = 204, p = 0.002), or quantitative RT-PCR (n = 371, p < 0.05). In conclusion, the increase in telomere length under treatment with imatinib reflects a shift from Ph+ to Ph- cells in the PB of patients with CML.

Chronic myeloid leukemia (CML) is a clonal disease of hematopoietic stem cells caused by a reciprocal translocation of the long arms of chromosomes 9 and 22. In human leukocyte antigen A*0201(+) (HLA-A*0201(+)) individuals, response after interferon-alpha (IFN-alpha) was shown to be associated with the emergence of CML-specific cytotoxic T cells that recognize PR-1, a myeloblastin (MBN)-derived nonapeptide. In contrast, imatinib potently induces remissions from CML by specific inhibition of the ABL tyrosine kinase. Here, we explored molecular regulations associated with CML responses under different treatment forms using cDNA-array. Expression of MBN was found to be down-regulated in remission under imatinib therapy (0 of 7 MBN(+) patients). In contrast, MBN transcription was readily detectable in the peripheral blood in 8 of 8 tested IFN-alpha patients in complete remission (P =.0002). IFN-alpha-dependent MBN transcription was confirmed in vitro by stimulation of peripheral blood mononuclear cells (PBMCs) with IFN-alpha and by IFN-alpha-mediated activation of the MBN promoter in reporter gene assays. Finally, with the use of HLA-A*0201-restricted, MBN-specific tetrameric complexes, it was demonstrated that all of 4 IFN-alpha-treated patients (100%), but only 2 of 11 imatinib patients (19%), in complete hematological or cytogenetic remission developed MBN-specific cytotoxic T cells (P =.011). Together, the induction of MBN expression by IFN-alpha, but not imatinib, may contribute to the specific ability of IFN-alpha to induce an MBN-specific T-cell response in CML patients. This also implies that the character of remissions achieved with either drug may not be equivalent and therefore a therapy modality combining IFN-alpha and imatinib may be most effective.

Selective inhibition of the BCR-ABL tyrosine kinase by imatinib (STI571, Glivec/Gleevec) is a promising new therapeutic strategy in patients with chronic myelogenous leukemia (CML). Despite significant hematologic and cytogenetic responses, resistance occurs, particularly in patients with advanced disease. We sought to determine the underlying mechanisms. Sixty-six patients with CML in myeloid blast crisis (n = 33), lymphoid blast crisis (n = 2), accelerated phase (n = 16), chronic phase (n = 13), and BCR-ABL-positive acute lymphoblastic leukemia (n = 2) resistant to imatinib were investigated. Median duration of imatinib therapy was 148 days (range 6-882). Patients were evaluated for genomic amplification of BCR-ABL, overexpression of BCR-ABL transcripts, clonal karyotypic evolution, and mutations of the imatinib binding site in the BCR-ABL tyrosine kinase domain. Results were as follows: (1) Median levels of BCR-ABL transcripts, were not significantly changed at the time of resistance but 7/55 patients showed a >10-fold increase in BCR-ABL levels; (2) genomic amplification of BCR-ABL was found in 2/32 patients evaluated by fluorescence in situ hybridization; (3) additional chromosomal aberrations were observed in 19/36 patients; (4) point mutations of the ABL tyrosine kinase domain resulting in reactivation of the BCR-ABL tyrosine kinase were detected in 23/66 patients. In conclusion, although the heterogeneous development of imatinib resistance is challenging, the fact that BCR-ABL is active in many resistant patients suggests that the chimeric oncoprotein remains a good therapeutic target. However, patients with clonal evolution are more likely to have BCR-ABL-independent mechanisms of resistance. The observations warrant trials combining imatinib with other agents.

History and Clinical Findings: A 60-year-old woman presented with night-sweats and increasing weakness. Physical examination revealed no abnormalities. For 27 years she had been treated for Philadelphia-positive chronic myeloid leukemia (CML). Because of progressive disease treatment with the tyrosine kinase inhibitor imatinib (STI571, Glivec (R)) had been started 9 months before. She had achieved complete hematological remission within 8 weeks, but not a cytogenetic response., Investigations: Elevated WBC count (26.7/nl) with a differential displaying typical features of acceleration in bone marrow aspirate confirmed CML in accelerated phase. Sequencing of the ATP binding site of the BCR-ABL gene, which - at protein level - is the target for imatinib, revealed the clonal selection of cells harboring a point mutation leading to the exchange of amino acid 253 from tyrosine to histidine. This was considered to be the cause of resistance to imatinib., Treatment and Course: Dose increase of imatinib up to 600 mg daily and administration of cytarabine did not overcome resistance. Imatinib therapy was discontinued; hematologic remission was induced by oral therapy with hydroxyurea and mercaptopurine. In the course of the following 6 months a gradual decrease of the resistant clone from 100 % down to lower than the detection limit of the method was demonstrated., Conclusions: Clonal mutations are often the cause of resistance to imatinib therapy. They can be detected by sequencing of the ATP binding site of BCR-ABL in specialized laboratories. This case shows that discontinuation of imatinib therapy can significantly reduce the mutated (resistant) clone and thereby restore sensitivity to imatinib.

The degree of tumor load reduction as measured by cytogenetic response is an important prognostic factor for chronic myelogenous leukemia (CML) patients on therapy. We sought to determine whether BCR-ABL transcript levels can predict chromosomal response. Residual disease was evaluated in 120 CML patients in chronic phase (CP) treated with the selective tyrosine kinase inhibitor imatinib after resistance or intolerance to interferon alpha (IFN). Median time of therapy was 401 days (range 111-704). BCR-ABL and total ABL transcripts were measured in 486 peripheral blood (PB) specimens with a real time RT-PCR approach using fluorescent-labeled hybridization probes (LightCycler technology) and results were expressed as the ratio BCR-ABL/ABL. Cytogenetic response was determined in 3-monthly intervals: From 101 evaluable patients, 42 achieved a complete (CR, 0% Philadelphia chromosome (Ph)- positive metaphases), 18 a partial (PR, 1-34% Ph+), 13 a minor (MR, 35-94% Ph+), and 26 no response (NR, >94% Ph+). All PB samples were RT-PCR positive. The proportion of Ph+ metaphases and simultaneous BCR-ABL/ABL ratios correlated with r = 0.74, P < 0.0001. In order to investigate whether early molecular analysis may predict cytogenetic response, quantitative RT-PCR data obtained after 1 and 2 months of therapy were compared with cytogenetic response at 6 months. BCR-ABL/ABL ratios after 1 month were not predictive, but results after 2 months correlated with the consecutive cytogenetic response (P = 0.0008). The probability for a major cytogenetic response was significantly higher in patients with a BCR-ABL/ABL ratio <20% after 2 months of imatinib therapy. We conclude that: (1) quantitative determination of residual disease with real time RT-PCR is a reliable and sensitive method to monitor CML patients on imatinib therapy; (2) BCR-ABL/ABL ratios correlate well with cytogenetic response; (3) in IFN-pretreated patients all complete responders to imatinib have evidence of residual disease with the limited follow-up available; and (4) cytogenetic response at 6 months of therapy in CP patients is predictable with real time RT-PCR at 2 months.

Standard Treatment: According to the evidence-based guidelines for the therapy of chronic myelogenous leukemia (CML) the combination of interferon alpha (IFN) and hydroxyurea with or without low dose ara-C is the standard treatment for chronic phase CML, if no allogeneic stem cell transplantation is requested. STI571: In cases of IFN failure the new tyrosine kinase inhibitor STI571 (Glivec) shows high response rates. STI571 specifically inhibits the BCR-ABL fusion protein which is pathogenetically relevant for CML and shows abnormal tyrosine kinase activity. 91% of all CML patients in chronic phase achieve a hematologic remission within 11 months and 55% cytogenetic remission. In blast crisis, 29% achieve hematologic remission which may be durable., Conclusion: The available data represent response rates. Until survival data are available, the evidence-based recommendations will remain valid.

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., (Copyright 2001 S. Karger GmbH, Freiburg)