Contribution of ABL kinase domain mutations to imatinib resistance in different subsets of Philadelphia-positive patients: by the GIMEMA Working Party on Chronic Myeloid Leukemia.

PURPOSE: ABL kinase domain mutations have been implicated in the resistance to the BCR-ABL inhibitor imatinib mesylate of Philadelphia-positive (Ph+) leukemia patients. EXPERIMENTAL DESIGN: Using denaturing high-performance liquid chromatography and sequencing, we screened for ABL kinase domain mutations in 370 Ph+ patients with evidence of hematologic or cytogenetic resistance to imatinib. RESULTS: Mutations were found in 127 of 297 (43%) evaluable patients. Mutations were found in 27% of chronic-phase patients (14% treated with imatinib frontline; 31% treated with imatinib post-IFN failure), 52% of accelerated-phase patients, 75% of myeloid blast crisis patients, and 83% of lymphoid blast crisis/Ph+ acute lymphoblastic leukemia (ALL) patients. Mutations were associated in 30% of patients with primary resistance (44% hematologic and 28% cytogenetic) and in 57% of patients with acquired resistance (23% patients who lost cytogenetic response; 55% patients who lost hematologic response; and 87% patients who progressed to accelerated phase/blast crisis). P-loop and T315I mutations were particularly frequent in advanced-phase chronic myeloid leukemia and Ph+ ALL patients, and often accompanied progression from chronic phase to accelerated phase/blast crisis. CONCLUSIONS: We conclude that (a) amino acid substitutions at seven residues (M244V, G250E, Y253F/H, E255K/V, T315I, M351T, and F359V) account for 85% of all resistance-associated mutations; (b) the search for mutations is important both in case of imatinib failure and in case of loss of response at the hematologic or cytogenetic level; (c) advanced-phase chronic myeloid leukemia and Ph+ ALL patients have a higher likelihood of developing imatinib-resistant mutations; and (d) the presence of either P-loop or T315I mutations in imatinib-treated patients should warn the clinician to reconsider the therapeutic strategy.     

Sudden blast crisis in patients with Philadelphia chromosome-positive chronic myeloid leukemia who achieved complete cytogenetic remission after imatinib therapy

BACKGROUND: Most patients with Philadelphia chromosome (Ph)-positive chronic myeloid leukemia (CML) in chronic phase (CP) who receive treatment with imatinib achieve complete cytogenetic remission (CCR), which is correlated tightly with long-term progression-free survival. In these patients, the occurrence of blastic crisis (BC) is rare, and its clinical biologic characteristics are not well known. METHODS: Among 164 patients who received imatinib and were followed for a median of 35 months, 11 patients (6.7%) developed a BC; this was sudden (i.e., it occurred within 3 months of a documented CCR) in 6 patients (54.5%). Those patients were analyzed with respect to their clinical and biologic features and were compared with previous reports. RESULTS: At the time of diagnosis, there were 3 low-risk patients and 3 intermediate-risk patients; 4 patients had received pretreatment with interferon, and 2 patients received only imatinib. The median CP was 18 months, and the median duration of imatinib therapy was 7 months. The median time to CCR was 3 months, and the median time from CCR to BC was 4 months. BC phenotype was lymphoid in 2 patients, myeloid in 3 patients (including 2 patients who had extramedullary localization), and biclonal in 1 patient. Karyotype evolution was detected in 4 patients, whereas a Ph-positive/Ph-negative mosaicism was evident in all 6 patients. One patient presented an M351T mutation. The overall median survival was 3 months. CONCLUSIONS: Sudden BC generally is an uncommon phenomenon that may be relatively frequent in patients with CML who receive imatinib. Clinical and biologic features also seem to characterize this peculiar type of abrupt disease evolution, which intervenes in patients' response to this drug. Close monitoring of disease markers and full disease eradication are warranted.     

EUTOS score predicts survival and cytogenetic response in patients with chronic phase chronic myeloid leukemia treated with first-line imatinib

Sokal, Euro and newly developed EUTOS scoring systems were validated in 220 Chinese chronic phase chronic myeloid leukemia (CP-CML) patients treated with frontline imatinib. In the EUTOS low-risk and high-risk groups, the 5-year OS was 98.7% vs. 71.4% (P < 0.0001), and the 5-year cumulative incidence of complete cytogenetic response (CCyR) was 92.4% vs. 53.8% (P < 0.0001). EUTOS score also predicted progression-free survival and duration of CCyR. Low EUTOS index predicted for CCyR. However, Sokal and Euro scores mainly could not discriminate the intermediate-risk from high-risk group in either survival or CCyR. EUTOS score forecasts the prognosis of CP-CML patients treated with first-line imatinib.     

Multiple BCR-ABL kinase domain mutations confer polyclonal resistance to the tyrosine kinase inhibitor imatinib (STI571) in chronic phase and blast crisis chronic myeloid leukemia

Through sequencing analysis of blood or bone marrow samples from patients with chronic myeloid leukemia, we identified BCR-ABL kinase domain mutations in 29 of 32 patients whose disease relapsed after an initial response to the tyrosine kinase inhibitor imatinib. Fifteen different amino acid substitutions affecting 13 residues in the kinase domain were found. Mutations fell into two groups-those that alter amino acids that directly contact imatinib and those postulated to prevent BCR-ABL from achieving the inactive conformational state required for imatinib binding. Distinct mutations conferred varying degrees of imatinib resistance. Mutations detected in a subset of patients with stable chronic phase disease correlated with subsequent disease progression. Multiple independent mutant clones were detected in a subset of relapsed cases. Our data support a clonal selection model of preexisting BCR-ABL mutations that confer imatinib resistance.     

甲磺酸马替尼治疗慢性髓细胞白血病急性髓性变的疗效

背景与目的:慢性髓细胞白血病急性髓性变后,治疗非常困难,预后极差。本文旨在探讨特异性BCR/ABL酪氨酸激酶抑制剂(甲磺酸马替尼,格列卫)治疗慢性髓细胞白血病急性髓性变的疗效。方法:甲磺酸马替尼治疗组19例与历史对照组22例均先用含阿糖胞苷的标准化疗方案诱导治疗2疗程后,治疗组用甲磺酸马替尼400mg/d继续巩固或诱导治疗,治疗4周如无效,则将剂量增加至600mg/d,继续治疗8周;如有效,则用该剂量继续维持,仍无效则停用。历史对照组则采用其他方案继续巩固或诱导治疗。结果:治疗组标准诱导治疗无效的16例患者用甲磺酸马替尼治疗,6例(38%)取得完全的血液学缓解,获大部分遗传学效应;2例(13%)获部分血液学缓解,1例(6%)回到慢性期,获小部分遗传学效应;总的血液学有效率为56%。存活1年者6例(38%)。对照组诱导治疗无效的18例患者采用其他方案诱导化疗,仅2例(11%)取得完全的血液学缓解;1例(6%)获部分血液学缓解,总有效率为17%;1年内存活者仅1例(6%)。两组比较,差异有显著性(P<0.05)。结论:甲磺酸马替尼治疗慢性髓细胞白血病急性髓性变疗效高、生存时间延长,且耐受性好。但仍存在复发和耐药问题。     

Dasatinib early intervention after cytogenetic or hematologic resistance to imatinib in patients with chronic myeloid leukemia

BACKGROUND:

Although many patients with chronic myeloid leukemia (CML) respond well to imatinib therapy, a significant proportion loses their initial response. Loss of response on imatinib is often because of BCR‐ABL mutations. Dasatinib is a 325‐fold more potent inhibitor of Bcr‐Abl than imatinib and has been associated with high rates of durable responses in patients with CML in chronic phase (CP) after imatinib failure.

METHODS:

To determine the optimal time for initiating dasatinib after loss of response on imatinib, data from dasatinib trials in CML‐CP were analyzed. Patients were grouped according to whether they received early intervention with dasatinib (ie, after cytogenetic recurrence on imatinib), rather than after both cytogenetic and hematologic recurrence.

RESULTS:

Overall, 72% of patients who received dasatinib after loss of a major cytogenetic response (MCyR) on imatinib achieved a complete cytogenetic response (CCyR) compared with 42% of patients who were treated after loss of both MCyR and complete hematologic response (CHR). Event‐free survival (EFS) also was higher after earlier dasatinib treatment (24‐month EFS rates: 89% after loss of MCyR on imatinib vs 29% after loss of both MCyR and CHR). Among patients who were treated after loss of CHR on imatinib with no prior MCyR, 26% achieved a CCyR with dasatinib, and the 24‐month EFS rate was 64%. In all 3 groups, CCyR rates were similar in patients with or without pre‐existing BCR‐ABL mutations.

CONCLUSIONS:

The results of the current study suggested that optimal outcomes are achieved when dasatinib is administered early after imatinib resistance. Cancer 2009. © 2009 American Cancer Society.     

Extramedullary blast crisis in a patient with Philadelphia chromosome-positive chronic myelogenous leukemia in complete cytogenetic remission

Treatment of Philadelphia (Ph) chromosome-positive chronic myelogenous leukemia (CML) with recombinant interferon-alpha (IFN-A) results in complete disappearance of the Ph chromosome in about 10% to 15% of patients in early chronic phase. This group has a long survival and very low incidence of blast crisis. The first known case is reported of extramedullary blastic transformation in a patient with medullary complete cytogenetic response (0% Ph-positive metaphases) to IFN-A. Four episodes of extramedullary blast crisis have occurred in this patient. The first three episodes were lymphoid by morphology and cytochemical stains. Molecular analysis confirmed breakpoint cluster region rearrangement. The most recent transformation was myeloid in nature and involved bone and pulmonary parenchyma. The patient is currently undergoing a second autologous transplantation with stored bone marrow that is Ph negative. The patient has survived more than 18 months since the first episode of blast crisis, and the bone marrow is normal.     

伊马替尼联合异基因造血干细胞移植治疗慢性粒细胞白血病急淋变三例

 目的　探讨采用伊马替尼（STI571，商品名：格列卫）联合异基因造血干细胞移植（allo-HSCT）治疗慢性粒细胞白血病（CML）急淋变的疗效。方法　3例CML急淋变患者移植前后均口服伊马替尼（200～800 mg／d）。以改良全身照射（TBI）＋环磷酰胺（Cy）或改良白消安（Bu）＋Cy为预处理方案。结果　3例患者均造血重建。3例患者均发生急性移植物抗宿主病（aGVHD），1例发生慢性GVHD（cGVHD）。2例患者复发，但最终均获得缓解。3例患者均无病生存，中位随访时间28（11～35）个月。结论　伊马替尼联合allo-HSCT治疗CML急淋变，能够降低移植前白血病细胞负荷，有利于移植后复发的治疗，是一种安全有效的治疗方法。。     

Addition of sargramostim (GM-CSF) to imatinib results in major cytogenetic response in a patient with chronic myeloid leukemia

Imatinib mesylate, an inhibitor of BCR/ABL tyrosine kinase, has remarkable activity in chronic myeloid leukemia resulting in an 87% major cytogenetic response. We describe a woman who failed to achieve any cytogenetic response after 2.5 years of imatinib, 400mg daily. When daily sargramostim (GM-CSF) 100 microg/m2 was added, cytogenetic studies revealed a gradual increase in percentage of normal cells from start, 4, 9, and 15 months at 0%, 10%, 55%, and 85%, respectively. She became transfusion independent after starting GM-CSF. The addition of GM-CSF to imatinib resulted in a clinical benefit and a major cytogenetic response in this patient.     

Acute blast crisis with EBV-infected blasts, in a patient with chronic myeloid leukemia, and vasculitis

Unless they undergo transplantation, all patients with chronic myeloid leukemia (CML) will eventually develop a late phase of acute blast crisis (ABC). Although additional chromosomal abnormalities to the Philadelphia (Ph) chromosome may herald ABC in many CML cases, the mechanisms leading to this fatal event are obscure. Viral etiology, including the Epstein-Barr virus (EBV) has never been implicated in the pathogenesis of ABC in CML. Iloprost is an analogue of epoprostenol (prostacyclin; PGI2) commonly used for the treatment of peripheral vascular diseases and acts via inhibition of platelet activation, and by vasodilation. A case of ABC with blasts of undetermined lineage showing EBV infection in a male patient with Ph positive CML is described here. This unusual event developed during a course of treatment with the prostacyclin analogue, iloprost administered for vasculopathic leg ulcers. The proliferating blasts stained positively by immunohistochemistry only for the leukocyte common antigen (LCA/CD-45), and the EBV-latent membrane protein 1 (LMP-1). The only chromosomal abnormality detected by cytogenetic analysis was the conventional Ph-chromosome. It is suggested that ABC in this case of CML, was associated with EBV-activated blasts of undetermined lineage.     

The addition of daunorubicin to imatinib mesylate in combination with cytarabine improves the response rate and the survival of patients with myeloid blast crisis chronic myelogenous leukemia (AFR01 study)

Background

The median survival of patients with chronic myelogenous leukemia in myeloid blast crisis (MBC-CML) is poor even for patients treated with tyrosine kinase inhibitors (TKIs).

Design and methods

We conducted a dose-escalating study of daunorubicin combined to fixed doses of IM (imatinib mesylate, 600 mg/d) and cytarabine (200 mg/d for 7 days), followed by hematopoietic stem cell transplantation or maintenance therapy with single-agent IM in patients with MBC-CML at onset or after failure of therapy excluding TKIs.

Results

Thirty-six patients were evaluated. Median follow-up is 6.1 years. Daunorubicin was escaladed up to 45 mg/m²/d 3 days. Twenty eight patients (77.7%) had hematologic response including 20 patients (55.5%) in complete hematologic response (CHR). Patients who received daunorubicin at 30-45 mg/m²/d had higher CHR rates compared to other patients. Median overall survival was 16 months. Overall survival in patients with hematological response was 35.4 months. Better results were observed in patients diagnosed with MBC-CML at onset.

Conclusions

The combination of IM with a standard “3 + 7” regiment was well tolerated and provided a high response rate. More than 55% of the patients achieved CHR and hematopoietic stem cell transplantation (SCT) was feasible in half of the cases. This trial was registered at www.clinicaltrials.gov as # NCT00219765.     

Frequent p53 gene mutations in blast crisis of chronic myelogenous leukemia, especially in myeloid crisis harboring loss of a chromosome 17p.

We investigated chromosome alterations and mutations of the p53 gene in 118 samples from 92 patients with chronic myelogenous leukemia in various clinical phases, i.e., chronic phase, accelerated phase, and blast crisis (BC). Single-strand conformation polymorphism analysis and subsequent nucleotide sequencing disclosed no alteration of the p53 gene in chronic phase (no mutation in 80 samples), while five of 31 BC samples showed point mutations: four in myeloid and one in lymphoid crisis. One of seven accelerated phase samples also showed a p53 gene mutation. Ten of 31 BC samples showed loss of one of the short arms of chromosome 17 (17p) through the formation of isochromosome 17q, i(17q), or unbalanced translocations. Loss of heterozygosity at the p53 locus in the accelerated phase and BC was detected only in two cases with i(17q) but not in seven cases with normal chromosome 17 homologues, suggesting that loss of one p53 allele is rare without cytogenetically detectable loss of a 17p. Among those six samples with p53 gene mutations, five showed loss of a 17p cytogenetically, and only one lymphoid crisis case exhibited normal chromosome 17 homologues. Thus, mutations of the p53 gene were closely associated with myeloid crisis with loss of a 17p (four mutations in ten samples), in contrast to myeloid crisis with normal chromosome 17 homologues (zero in 13) or lymphoid crisis (one in seven). Our results also suggest that alterations of the p53 gene might occur after loss of a 17p during the course of chronic myelogenous leukemia.     

Extramedullary blast crisis in a patient with chronic myelogenous leukemia in complete cytogenetic and molecular remission on interferon-alpha therapy

We report the previously undescribed occurrence of extramedullary blast crisis in a patient with chronic myelogenous leukemia in complete cytogenetic and molecular remission on interferon-alpha. Development of bilateral testicular swelling prompted a biopsy showing stromal infiltration with CD20 and TdT positive immature cells. On repeated examinations, the bone marrow remained BCR/ABL negative by RT-PCR analysis. However, the cerebrospinal fluid (CSF) contained atypical lymphocytes positive for the P210 BCR-ABL product. Following treatment with testicular irradiation, intrathecal methotrexate, systemic chemotherapy and an unrelated donor transplant, the patient showed no evidence of disease until 9 months post-transplant, when he relapsed in lymphoid blast crisis in both bone marrow and CSF.     

Allogeneic stem-cell transplantation provides excellent results in advanced stage chronic myeloid leukemia with major cytogenetic response to pre-transplant imatinib therapy

To determine the impact of imatinib therapy prior to allogeneic stem-cell transplantation in advanced stage chronic myelogenous leukaemia (CML), 30 CML patients who had received imatinib as part of pre-transplant treatment were analysed, with special emphasis on the cytogenetic response to imatinib therapy shortly before transplantation. Median patient age was 51 years (range, 24 - 64). At the time of transplantation all patients were in second or higher chronic phase (CP). The median follow-up after allogeneic transplantation was 360 days (range, 24 - 1524). Cox regression analysis revealed that the quality of cytogenetic response was a prognostic factor for transplant-related mortality (p = 0.050), relapse incidence (p = 0.015), leukaemia-free survival (p = 0.002) and overall survival (p = 0.006). A cytogenetic response with <35%BCR-ABL-positive interphase nuclei in FISH analysis from bone marrow was associated with a probability of overall survival of 81% at 3 years. In conclusion, our data suggest that advanced stage CML has an excellent outcome after allogeneic haematopoietic stem-cell transplantation when transplanted in the phase of cytogenetic response to imatinib.