Serial monitoring of BCR-ABL by peripheral blood real-time polymerase chain reaction predicts the marrow cytogenetic response to imatinib mesylate in chronic myeloid leukaemia

Comparison of 3-month cytogenetic and molecular assays for early assessment of long-term clinical impact after BCR-ABL1 tyrosine kinase inhibitor treatment in chronic myeloid leukemia

To compare the clinical significance of 3-month cytogenetic and molecular monitoring, we analyzed 1,410 paired cytogenetic and molecular data from 705 chronic-phase chronic myeloid leukemia patients. Based on early cytogenetic response (ECyR, Ph+≤35 %) and molecular response (EMR, BCR-ABL1^IS≤10 %) at 3 months, the patients were divided into four groups (group 1: ECyR + EMR, n = 560; group 2: no ECyR + EMR, n = 27; group 3: ECyR + no EMR, n = 55; group 4: no ECyR + no EMR, n = 63). By 10 years, major molecular response (MMR), deep molecular response (MR4.5), overall survival (OS), and progression-free survival (PFS) rates were significantly high in group 1 (P < 0.001). Comparing groups 2 and 3, the MMR (P = 0.096), MR4.5 (P = 0.945), OS (P = 0.832), and PFS (P = 0.627) rates tended to be higher in group 2, although not significantly. Thus, the cytogenetic assay can not only be useful but its addition may also provide a more precise prediction of MR4.5.

Multiplex technologies for the assessment of minimal residual disease and low-level mutation detection in leukaemia: mass spectrometry versus next-generation sequencing

With the focus of leukaemia management shifting to the implications of low-level disease burden, increasing attention is being paid on the development of highly sensitive methodologies required for detection. There are various techniques capable of identification of measurable residual disease (MRD) either evidencing as relevant mutation detection [e.g. nucleophosmin 1 (NPM1) mutation] or trace levels of leukaemic clonal populations. The vast majority of these methods only permit detection of a single clone or mutation. However, mass spectrometry and next-generation sequencing enable the interrogation of multiple genes simultaneously, facilitating a more complete genomic profile. In the present review, we explore the methodologies of both techniques in conjunction with the important advantages and limitations associated with each assay. We also highlight the evidence and the various instances where either technique has been used and propose future strategies for MRD detection.

New Tool for Monitoring Molecular Response in Patients With Chronic Myeloid Leukemia

OBJECTIVE

Chronic myeloid leukemia treatment monitoring using polymerase chain reaction-based peripheral blood testing of t9;22 BCR-ABL1 provides improved test sensitivity over cytology but suffers from inadequate standardization in most laboratories due to variations inherent in the existing polymerase chain reaction methodologies. We performed the initial analytic performance evaluation of a novel competitive template-based peripheral blood b2a2/b3a2 transcript abundance method, called standardized nucleic acid quantification (SNAQ) test, with hypothesis that this will produced more consistent results with less frequent interlaboratory variations.

MATERIALS AND METHODS

Thirty-six chronic myeloid leukemia patients treated at our institution were enrolled. We compared SNAQ test with 2 laboratory developed test at the MD Anderson molecular diagnostic laboratory and Cancer Genetics Institute for analyzing BCR-ABL1 from peripheral blood samples. Each test result (n=36) was ranked against all the other samples tested by the same method.

RESULTS

The Pearson correlation between SNAQ and laboratory developed test done at 2 labs was met by correlations of 0.97, 0.96, 0.96, and 0.94. Analysis of variance of log %BCR-ABL1 interlaboratory results indicated no significant difference (P=0.98). Post hoc analysis of method agreement showed the SNAQ method had a 95% limit of agreement of ±3-fold between laboratories.

CONCLUSIONS

In this pilot study, SNAQ methodology performed consistent with half-log accuracy. Additional studies from a larger sample size and correlation with clinical outcomes are required to confirm this observation.

Factors Affecting Early Molecular Response in Chronic Myeloid Leukemia

OBJECTIVES

There is controversy about whether 3- or 6-month molecular assessment predicts progression-free and overall survival in those with chronic myeloid leukemia (CML). The factors predicting molecular response at 3, 6, and 12 months have not been studied extensively. The study objective was to study the factors affecting molecular response at 3 and 6 months in patients with CML who are receiving imatinib mesylate.

METHODS

We prospectively enrolled patients with newly diagnosed CML who were receiving imatinib mesylate as the initial therapy for CML. The diagnosis of CML was based on clinical examination, bone marrow, and demonstration of BCR ABL(IS) transcripts by polymerase chain reaction. The molecular response(IS) was assessed at 3, 6, and 12 months by GeneXpert (Cepheid, Sunnyvale, CA) and co-related with various baseline characteristics of patients. We also looked at whether early achievement of a complete hematologic response within 6 weeks predicts molecular response at 3 or 6 months. The study took place at a tertiary care hospital in Northwest India catering to patients belonging to low-middle socioeconomic status.

RESULTS

We enrolled 131 patients with CML in the chronic phase from July 1, 2013, to August 31, 2014. The median age of the patients was 40 years (range, 13-67) with a male preponderance (61% were male). Most patients presented with symptoms of low-grade fever (52.7%) and abdominal fullness (26.7%). Spleen was palpable in 84.7% of patients. The median hemoglobin at presentation was 10.8 g/dL (range, 4.8-18.4 g/dL), white cell count was 138.3 × 10(9)/L (4.1-697 × 10(9)/L), and platelet count was 326 × 10(9)/L (85-1819 × 10(9)/L). The median number of peripheral blood basophils was 3% (range, 0%-20%), and blasts were 3% (range, 0%-10%). Myelofibrosis of more than grade 1 was present in 30% of patients. Most patients belonged to intermediate Sokal (45.8%) and Hasford (55%) scores and low EUropean Treatment Outcome Study (78.6%) score. Of 128 evaluable patients at 3 months, 96.9% achieved complete hematologic remission (CHR) and 82.3% achieved BCR ABL(IS) of less than 10%. None of the patients who had BCR ABL(IS) > 10% at 3 months achieved BCR ABL(IS) < 1% at 6 months or < 0.1% at 12 months. Early achievement of CHR (< 6 weeks), peripheral blood blast count of < 5%, and lactate dehydrogenase < 851 U/L were significantly associated with achievement of BCR ABL(IS) < 10% at 3 months and BCR ABL(IS) < 1% at 6 months.

CONCLUSIONS

We found that BCR ABL(IS) assessment at 3 months is superior to assessment at 6 months. Patients with CML in the chronic phase who achieve CHR within 6 weeks are more likely to achieve BCR ABL(IS) < 10% at 3 months and < 1% at 6 months than patients who achieve CHR between 7 and 12 weeks.

Treatment Outcomes in CML Patients Treated With Tyrosine Kinase Inhibitors at a Tertiary Teaching Hospital in South Africa

BACKGROUND

Chronic myeloid leukemia (CML) has become one of the most treatable hematologic neoplasms since the advent of the tyrosine kinase inhibitors (TKIs), but it was not known if similar treatment outcomes could be achieved in a resource-limited country. We tested the hypothesis that, despite challenges to access to second-generation TKIs, excellent responses could be replicated in the setting of limited resources.

PATIENTS AND METHODS

Records of 58 patients with newly diagnosed CML in the chronic phase treated with TKIs at a tertiary teaching hospital in Cape Town, South Africa between 2003 and 2012 were reviewed and assessed according to European LeukemiaNet (ELN) criteria.

RESULTS

After a median follow-up of 60.5 months, progression-free survival at 60 and 96 months was 79.98% and 68.4%, respectively. Overall survival at 60 and 96 months was 92.9% and 83.6%, respectively. Progression to blast phase at 60 months was associated with poorer survival (P = .0002) but progression to accelerated phase was not (P = .1456). Attainment of a complete cytogenetic response at 12 months (P = .28) or major molecular response at 18 months (P = .268) did not have prognostic significance.

CONCLUSION

Despite delays in achievement of the target responses defined according to ELN criteria, the use of imatinib mesylate as a first-line treatment can still result in treatment outcomes comparable with those in developed countries. These data suggest opportunities for improvement and success might be even greater with uninterrupted access to second-generation or newer TKIs.

Reconsideration of BCR-ABL protein flow cytometric immunobead assay: how potent to diagnose and monitor chronic myeloid leukemia?

INTRODUCTION

Chronic myeloid leukemia (CML) is typically associated with the Philadelphia chromosome, resulting in the production of BCR-ABL fusion oncoprotein with upregulated tyrosine kinase activity. We aimed to evaluate a new flow cytometric immunobead assay to detect BCR-ABL protein in a group of patients with CML.

METHODS

We enrolled 49 patients with CML, whose qRT-PCR and/or cytogenetic analysis of Philadelphia chromosome aberration was available, including tyrosine kinase inhibitors (TKIs)-naïve and (TKIs)-treated patients with various levels of response. Twenty Philadelphia-negative healthy individuals were also enrolled to obtain analytical negative controls. Peripheral blood samples were analyzed for BCR-ABL fusion protein by flow cytometry.

RESULTS

The BCR-ABL fusion protein flow cytometric assay seemed efficacious to both diagnose the presence (P-value <0.0001) and distinguish the levels (P-value = 0) of the Philadelphia chromosome aberration. Groups of TKI-naïve and TKI-treated patients as well as levels of molecular/cytogenetic response to TKI-therapy were effectively discriminated (P-value <0.01). The receiver operating characteristic (ROC) curve analysis indicated the diagnostic value of the assay as excellent (AUC = 0.95, P-value = 0).

CONCLUSIONS

The evaluated BCR-ABL fusion protein assay might be useful for diagnosing and monitoring Philadelphia chromosome aberration.

Low leukotriene B4 receptor 1 leads to ALOX5 downregulation at diagnosis of chronic myeloid leukemia

ALOX5 is implicated in chronic myeloid leukemia development in mouse leukemic stem cells, but its importance in human chronic myeloid leukemia is unknown. Functional ALOX5 was assessed using an LTB4 ELISA and ALOX5, and LTB4R1 mRNA expression was determined via a TaqMan gene expression assay. LTB4R1 and 5-LOX protein levels were assessed by cell surface flow cytometry analysis. At diagnosis ALOX5 was below normal in both blood and CD34(+) stem cells in all patients. On treatment initiation, ALOX5 levels increased in all patients except those who were destined to progress subsequently to blast crisis. LTB4 levels were increased despite low ALOX5 expression, suggesting that the arachidonic acid pathway is functioning normally up to the point of LTB4 production. However, the LTB4 receptor (BLT1) protein in newly diagnosed patients was significantly lower than after a period of treatment (P<0.0001). The low level of LTB4R1 at diagnosis explains the downregulation of ALOX5. In the absence of LTB4R1, the arachidonic acid pathway intermediates (5-HEPTE and LTA4) negatively regulate ALOX5. ALOX5 regulation is aberrant in chronic myeloid leukemia patients and may not be important for the development of the disease. Our data suggest caution when extrapolating mouse model data into human chronic myeloid leukemia.

Correlations between cytogenetic and molecular monitoring among patients with newly diagnosed chronic myeloid leukemia in chronic phase: post hoc analyses of the Rationale and Insight for Gleevec High-Dose Therapy study

CONTEXT

Although bone marrow (BM) karyotyping has been the standard in monitoring patients with chronic myeloid leukemia, peripheral blood (PB) monitoring methods may be more convenient.

OBJECTIVE

To conduct post hoc analyses of the Rationale and Insight for Gleevec High-Dose Therapy study to evaluate correlations between results of cytogenetic testing and molecular monitoring from BM and PB during the first 18 months of high-dose imatinib therapy, and between early and late molecular responses.

DESIGN

Newly diagnosed patients with chronic-phase chronic myeloid leukemia received imatinib 400 mg twice daily and were monitored quarterly for up to 18 months. Cytogenetic testing was performed by karyotyping using BM or by fluorescence in situ hybridization using PB. Molecular testing was performed by quantitative reverse transcriptase polymerase chain reaction using BM and PB.

RESULTS

Significant pairwise correlations were found between results obtained by karyotyping, fluorescence in situ hybridization, and quantitative reverse transcriptase polymerase chain reaction using PB or BM (all pairwise correlations >0.8; P < .001). At 12 months, cytogenetic response by karyotyping correlated well with response by fluorescence in situ hybridization. A median 2.579-log reduction in BCR-ABL1 level from a standardized baseline correlated with fluorescence in situ hybridization-negative status. Patients with greater than 2-log reduction in BCR-ABL1 level at 3, 6, and 9 months were more likely to achieve major molecular response at 18 months than those with 2-log reduction or less.

CONCLUSIONS

Our findings support the feasibility of molecular monitoring using PB and suggest that molecular monitoring conducted at a single reliable reference laboratory can adequately track response without invasive BM testing. Our findings are consistent with other work indicating that early response to imatinib predicts favorable long-term outcome.

Chronic myeloid leukemia treatment with Imatinib: An experience from a private tertiary care hospital

The data presents 75 chronic myeloid leukemia patients diagnosed over a period 6 years i.e. from 2002 to 2008. The most common presentation was splenomegaly and 97% achieved complete hematological response at median duration of 4.3 weeks. The uniqueness of this study is follow-up with molecular response monitoring. Nearly, 30% patients achieved major molecular response (MMoR) by 12 months. 70% of patients achieved MMoR by median time of 60 months. Only 10% of the patient who achieved MMoR by 18 months had lost their responses subsequently.

Report of chronic myeloid leukemia in chronic phase from Tata Memorial Hospital, Mumbai, 2002-2008

Background:

Chronic myeloid leukemia (CML) is the commonest hematological malignancy in India. This manuscript is a single center analysis CML in chronic phase (CP).

Materials and Methods:

We did retrospective analysis of almost 1000 patients registered as chronic myeloid leukemia over a period of 6 years at Tata Memorial Hospital.

Results:

We found striking difference in cytogenetic response among patients presenting in late chronic phase (CP) compared with the patients in early CP. The rate of complete cytogenetic response among patients in late CP was 60% while in early CP it was 80%, which was statistically significant (P = 0.0001). The overall survival was 86%, at a median follow-up of 51 months. Innovator glivec was taken by 671 patients among which complete cytogenetic response (CCyR) was seen in 72% whereas generic veenat was taken by 237 patients and CCyR was seen in 75% of them.

Conclusion:

Availability of imatinib has dramatically changed the outlook for CML in India. The response was identical for those treated with innovator brand of imatinib as compared to the generic brand. Hence quality generics provide a cost effective solution, which is particularly relevant in the current global scenario.

A population study showing that the advent of second generation tyrosine kinase inhibitors has improved progression-free survival in chronic myeloid leukaemia

BACKGROUND

Population based data suggest the proportion of patients failing imatinib in chronic myeloid leukaemia (CML) is higher than the reported one-third of patients in clinical trials. Clinical trials have demonstrated second generation tyrosine kinase inhibitors (TKI) dasatinib and nilotinib can restore complete cytogenetic remission (CCR) and major molecular response (MMR) to many patients failing imatinib, but their impact in the general population is not clear.

DESIGN AND METHODS

We report CML outcome in a population of 2.3 million people in a geographically contiguous area of North West England and North Wales.

RESULTS

Between 2003 and 2009, 192 new CML cases were diagnosed, of whom 184 were in chronic phase and 160 started on imatinib. The maximal CCR rate was 65% at 24 months and the maximal MMR rate was 50% at 36 months. Patients diagnosed since second generation TKI became available for imatinib failure had a more rapid cumulative CCR and MMR rate and a significantly improved progression free survival (p=0.022) than those diagnosed before this time.

CONCLUSION

The study indicates that second generation TKI have improved CML outcome in the general population.

Monitoring of BCR-ABL levels in chronic myeloid leukemia patients treated with imatinib in the chronic phase - the importance of a major molecular response

BACKGROUND

Real time PCR has become the most common technique to monitor BCR-ABL transcript levels of patients treated with kinase inhibitors. The aim of this study was to evaluate BCR-ABL levels of chronic myeloid leukemia patients treated with imatinib in the chronic phase and correlate the response to therapy and event-free survival.

METHODS

BCR-ABL levels were measured in peripheral blood cell samples using Real time PCR at diagnosis and then every 3 months after starting therapy with imatinib. Major molecular response was defined as a three-log reduction from the standardized baseline value. Major molecular response values were adjusted to international scale using a conversion factor of 1.19. The results are reported as a BCR-ABL/ABL ratio (%).

RESULTS

Hematological, major cytogenetic and complete cytogenetic responses were achieved by 57 (95%), 45 (75%) and 38 (63%) patients, respectively. Twenty-four out of sixty patients achieved a major molecular response (40%) in a median time of 8.5 months. Overall survival and event free survival were higher for patients with (100%) versus patients without (77%) a complete cytogenetic response (p-value = 0.01) at 48 months. Patients with complete cytogenetic response and major molecular response had a higher event free survival compared to patients with complete cytogenetic response but without major molecular response (p-value = 0.007).

CONCLUSION

In conclusion, the prognostic impact of achieving complete cytogenetic response and a major molecular response and also the importance of molecular monitoring in the follow-up of chronic myeloid leukemia patients were demonstrated.s.

Peroxisome proliferator-activated receptor activation increases imatinib uptake and killing of chronic myeloid leukemia cells

Low pretreatment expression of the imatinib uptake transporter human organic cation transporter 1 (hOCT1) is associated with inferior complete cytogenetic response rates, progression-free survival, and overall survival in imatinib-treated chronic myeloid leukemia (CML). Upregulation of hOCT1 can therefore increase the uptake of imatinib. The hOCT1 gene is transactivated by hepatocyte nuclear factor 4α in human liver, and peroxisome proliferator-activated receptors (PPAR) α and γ activation increases OCT1 expression in mouse hepatocytes. Here we report that no isoform of hepatocyte nuclear factor 4α is expressed in CML lines or in CML primary cells. In contrast, both PPARα and γ were expressed in all CML cell lines and primary cells studied. PPARα agonist treatment increased imatinib killing of CML KCL22 cells and primitive CD34(+) cells, and also upregulates hOCT1 gene expression and increases imatinib uptake into KCL22 cells and primary cells. PPARα agonists might potentially be of clinical use in CML patients failing imatinib.

Predictive value of early molecular response in patients with chronic myeloid leukemia treated with first-line dasatinib

Dasatinib is effective therapy for newly diagnosed patients with chronic myeloid leukemia, but not all patients respond well. We analyzed the outcome of patients treated with dasatinib as first-line therapy to identify patients who are more likely to fare poorly. The 8.6% of patients who at 3 months had a BCR-ABL1/ABL1 ratio > 10% had a significantly worse 2-year cumulative incidence of complete cytogenetic response (58.8% vs 96.6%, P < .001) and molecular responses than the remaining patients with a lower transcript levels. The predictive value of the 3-month transcript level could be improved using the dasatinib-specific transcript level cut-offs, namely, 2.2%, 0.92%, and 0.57% for complete cytogenetic response, 3 log and 4.5 log reductions in the transcript level, respectively. The study was registered at www.clinicaltrials.gov as #NCT01460693.

Cancerous inhibitor of PP2A (CIP2A) at diagnosis of chronic myeloid leukemia is a critical determinant of disease progression

Prospective identification of patients whose chronic myeloid leukemia (CML) will progress to blast crisis is currently not possible. PP2A is a phosphatase and tumor suppressor that regulates cell proliferation, differentiation, and survival. Cancerous inhibitor of PP2A (CIP2A) is a recently described inhibitor of PP2A in breast and gastric cancer. The aim of this study was to investigate whether CIP2A played a role in CML and whether PP2A or its inhibitor proteins CIP2A or SET could predict clinical outcome. At the time of diagnosis of CML, patients who will later progress to blast crisis have significantly higher levels of CIP2A protein (P < .0001) than patients who do not progress, suggesting that PP2A is functionally inactive. We show that the potential mechanism for disease progression is via altered phosphorylation of the oncogene c-Myc. Knockdown of CIP2A results in increased PP2A activity, decreased c-Myc levels, and a decrease in BCR-ABL1 tyrosine kinase activity. We demonstrate that CIP2A levels at diagnosis can consistently predict patients who will progress to blast crisis. The data show that CIP2A is biologically and clinically important in CML and may be a novel therapeutic target.

High-density single nucleotide polymorphism array analysis and ASXL1 gene mutation screening in chronic myeloid leukemia during disease progression

We have undertaken a genome-wide single nucleotide polymorphism (SNP) array analysis of 41 chronic myeloid leukemia (CML) patients. In total, 44 regions of uniparental disomy (UPD) >3 Mb were identified in 24 of 32 patients in chronic phase (CP), and 21 regions of UPD >3 Mb were identified in 13 of 21 patients in blast crisis (BC). Chromosome 8 had the highest frequency of UPD regions in both CP and BC samples. Eight recurrent regions of UPD were observed among the 41 patients, with chromosome 8 showing the highest frequency. Ten regions of copy number change (CNC) >3 Mb were observed in 4 of 21 patients in BC, whereas none were observed in CP. We have identified several recurrent regions of UPD and CNC in CML that may be of pathogenetic importance. Overrepresentation of genomic aberrations (UPD and copy number gain) mapping to chromosome 8 was observed. Selected candidate genes mapping within the aberrant genomic regions were sequenced and mutation of the TP53 gene was observed in one case in BC and of the ASXL1 gene in 6 of 41 cases in CP or BC. Mutation of ASXL1 represents an important new molecular abnormality in CML.

The use of imatinib mesylate as a lifesaving treatment of chronic myeloid leukemia relapse after bone marrow transplantation

We describe the response of imatinib as lifesaving treatment of chronic myeloid leukemia (CML) relapse in seven patients who underwent allogeneic bone marrow transplantation (alloBMT) at our institution over a period of 4 years. Retrospective analysis of their medical records revealed that a mean age at transplant was 45.2 years. The median time to diagnosis was 7.4 years after transplant. At relapse, four, two, and one patients were classified as having hematologic, major molecular, and cytogenetic relapse, respectively. At imatinib initiation, five had CML in a chronic phase, while one patient was diagnosed as having accelerated phase and blast crisis. All these patients could be evaluated for the therapeutic efficacy. At a mean of follow-up of 1.9 years of therapy, all evaluable patients achieved major molecular response without compromising safety. Consistent with available data, our results indicate that imatinib is safe and effective treatment option for patients with relapse after BMT.

Molecular diagnosis of hematopoietic and lymphoid neoplasms

This chapter summarizes the significance and molecular diagnostic detection of genetic abnormalities commonly associated with hematolymphoid neoplasms. Methodologic aspects of laboratory diagnosis are presented, as well as discussion of multiparameter genotyping of tumors for prognosis and the role of minimal residual disease monitoring in specific neoplasms.

Chronic myeloid leukemia patients with the e13a2 BCR-ABL fusion transcript have inferior responses to imatinib compared to patients with the e14a2 transcript

BACKGROUND

Chronic myeloid leukemia is characterized by a reciprocal translocation between chromosomes 9 and 22, creating the fusion gene BCR-ABL. The clinical significance of the type of BCR-ABL transcript in newly diagnosed patients in chronic phase treated with imatinib 400 mg from initial diagnosis remains unknown.

DESIGN AND METHODS

We analyzed the clinical outcome of 78 newly diagnosed chronic phase patients, aged 16 or over, treated with imatinib 400 mg. Of these, 71 expressed either e13a2 or e14a2 transcripts. BCR-ABL transcripts were assayed by quantitative real-time polymerase chain reaction.

RESULTS

After 12 months of treatment, 54% of the e14a2 patients had achieved a complete cytogenetic response, compared to 25% of the e13a2 patients (p=0.01). Kaplan-Meier analysis of the time to achieve complete cytogenetic response revealed that e14a2 patients had more rapid response rates, compared to e13a2 patients (p=0.006). e14a2 patients had a higher event-free survival rate in the first 12 months of treatment, although overall survival did not differ significantly between the patients with the two types of transcript. Human organic cation transporter protein 1 mRNA levels did not differ between the patients with the two types of transcript. The pre-treatment pCrKL/CrKL ratio (a surrogate marker of BCR-ABL tyrosine kinase activity) was higher in patients with e13a2 transcripts than in those with e14a2 (p=0.017).

CONCLUSIONS

Patients expressing the e14a2 transcript type have a higher rate and more rapid complete cytogenetic responses than e13a2-expressing patients, which may be due to higher BCR-ABL tyrosine kinase activity. Knowledge of the transcript type may yield additional prognostic information, although this requires testing on larger datasets.

Desirable performance characteristics for BCR-ABL measurement on an international reporting scale to allow consistent interpretation of individual patient response and comparison of response rates between clinical trials

An international basis for comparison of BCR-ABL mRNA levels is required for the common interpretation of data derived from individual laboratories. This will aid clinical decisions for individual patients with chronic myeloid leukemia (CML) and assist interpretation of results from clinical studies. We aligned BCR-ABL values generated by 38 laboratories to an international scale (IS) where a major molecular response (MMR) is 0.1% or less. Alignment was achieved by application of laboratory-specific conversion factors calculated by comparisons performed with patient samples against a reference method. A validation procedure was completed for 19 methods. We determined performance characteristics (bias and precision) for consistent interpretation of MMR after IS conversion. When methods achieved an average BCR-ABL difference of plus or minus 1.2-fold from the reference method and 95% limits of agreement within plus or minus 5-fold, the MMR concordance was 91%. These criteria were met by 58% of methods. When not met, the MMR concordance was 74% or less. However, irrespective of precision, when the bias was plus or minus 1.2-fold as achieved by 89% of methods, there was good agreement between the overall MMR rates. This indicates that the IS can deliver accurate comparison of molecular response rates between clinical trials when measured by different laboratories.

Reverse transcription with random pentadecamer primers improves the detection limit of a quantitative PCR assay for BCR-ABL transcripts in chronic myeloid leukemia: implications for defining sensitivity in minimal residual disease

BACKGROUND

Real-time quantitative reverse transcription PCR (RQ-PCR) assay for BCR-ABL is used to monitor treatment response in chronic myeloid leukemia (CML). BCR-ABL transcript levels decline over several years of imatinib treatment, and increasing numbers of patients have BCR-ABL transcripts at or below the limit of detection. More sensitive PCR methods are required to assess whether these patients have a long-term continuing decline in residual disease.

METHODS

We used random pentadecamer (R15) primers for reverse transcription in RQ-PCR and compared the results with our established method that uses random hexamers. An increase in assay sensitivity would be detected as an increase in the number of BCR-ABL transcripts.

RESULTS

BCR-ABL transcripts increased by 86% with R15 primers. We used R15 primers to retest 19 samples from selected CML patients who had no BCR-ABL transcripts recently detectable with hexamer primers and detected BCR-ABL transcripts in 68% of the samples. Use of R15 primers showed variable increases in the transcripts for control genes BCR (breakpoint cluster region), ABL1 (c-abl oncogene 1, receptor tyrosine kinase), and GUSB (glucuronidase, beta), depending on the gene examined. The reported BCR-ABL/control gene ratio was affected, and the estimated detection limit of the assay, which was based on increased control gene copy number, was different for each control gene.

CONCLUSIONS

This simple modification to the reverse transcription methodology improved the detection limit of the RQ-PCR assay for BCR-ABL transcripts. In the field of CML, these results have important implications for defining the detection limit of an assay when the BCR-ABL transcript is undetectable. Random pentadecamer primers may also be useful in other reverse transcription PCR assays for which the abundance of the target RNA is low.

Quantitative detection of bcr-abl transcripts in chronic myeloid leukemia

The optimal management of malignant haematological disorders depend on the degree of tumor load reduction after therapy. Chronic myeloid leukemia constitutes a clinical model for molecular detection and therapy surveillance of malignant disease since this entity was the first leukemia shown to be associated with a specific bcr-abl fusion gene in the patient's leukemia cells. Molecular monitoring of bcr-abl transcript levels by real-time quantitative PCR is increasingly used to assess treatment response in patients with chronic myeloid leukemia (CML). This has become particularly relevant in the era of imatinib therapy when residual levels of leukaemia usually fall below the level of detection by bone marrow cytogenetic analysis. We monitored bcr-abl transcript levels by quantitative real time PCR in 50 tunisian patients treated with imatinib for chronic myeloid leukemia in chronic phase for a median of 29 months (3-60) after they started imatinib.

Clinical evaluation of BCR-ABL peptide immunisation in chronic myeloid leukaemia: results of the EPIC study

Peptides from the e14a2 BCR-ABL junction will elicit T-cell responses in vitro. Here, 19 imatinib treated CML patients in first chronic phase were vaccinated with BCR-ABL peptides spanning the e14a2 fusion junction, some of which were linked to the pan DR epitope PADRE to augment CD4+ T cell help. Six vaccinations were given over 9 weeks, together with sargramostim. All patients developed mild local reactions. T cell responses to PADRE were seen in all patients. Fourteen of 19 patients developed T cell responses to BCR-ABL peptides. The development of an anti-BCR-ABL T cell response correlated with a subsequent fall in BCR-ABL transcripts. No molecular benefit was seen in the 5 patients not in major cytogenetic response (MCR) at baseline. However, of the 14 patients in MCR at baseline, 13 developed at least 1 log fall in BCR-ABL transcripts, though this occurred several months after completing vaccination, consistent with an effect at a primitive CML stem cell level. Vaccination may improve the fall in BCR-ABL transcripts in patients who have received imatinib for more than 12 months. BCR-ABL peptide vaccination may improve control of CML, especially in patients responding well to imatinib. Randomised trials are required to address this further.

Expression of the uptake drug transporter hOCT1 is an important clinical determinant of the response to imatinib in chronic myeloid leukemia

Some chronic myeloid leukemia (CML) patients do not respond to imatinib, whereas others lose an initial response. To identify potential imatinib failures, we investigated the expression of imatinib uptake transporter (human organic cation transporter 1; hOCT1) and efflux transporters (ATP-binding cassette transporters ABCB1, ABCG2, and ABCC1) using real-time quantitative reverse transcription-polymerase chain reaction in 70 CML patients. Patients with high pretreatment hOCT1 expression had superior complete cytogenetic response (CCR) rates (P=0.008), progression-free and overall survival (P=0.01 and 0.004). Pretreatment ABCB1, ABCG2, and ABCC1 levels did not correlate with treatment outcome. Regression analysis demonstrated that pretreatment hOCT1 expression was the most powerful predictor of CCR achievement at 6 months (P=0.002). Imatinib uptake into a CML cell line with high hOCT1 expression was greater than into those with modest or low expression (P=0.002). The expression of hOCT1, but not efflux transporters, is important in determining the clinical response to imatinib.

Imatinib: a review of its use in chronic myeloid leukaemia

Imatinib (Gleevec, Glivec) is a synthetic tyrosine kinase inhibitor used in the treatment of chronic myeloid leukaemia (CML). It is specifically designed to inhibit the breakpoint cluster region (BCR)-Abelson (ABL) fusion protein that results from the chromosomal abnormality known as the Philadelphia chromosome. CML is characterised by this abnormality, which leads to abnormalities of the peripheral blood and bone marrow including an increase in the number of granular leukocytes. Imatinib is approved in numerous countries worldwide for the treatment of newly diagnosed Philadelphia chromosome-positive (Ph+) chronic-phase CML, Ph+ accelerated-phase or blast-crisis CML, and in patients with Ph+ chronic-phase CML who have failed to respond to interferon-alpha therapy. It is also indicated in paediatric patients with newly diagnosed Ph+ chronic-phase CML, in accelerated-phase or blast-crisis CML, or in chronic-phase CML after failure of interferon-alpha therapy or when the disease has recurred after haematopoietic stem cell transplantation (HSCT). Approved indications, however, may vary by country. Imatinib is effective and generally well tolerated in patients with Ph+ CML. In patients with newly diagnosed chronic-phase CML, imatinib was more effective than interferon-alpha plus cytarabine in preventing progression of the disease and in achieving haematological and cytogenetic responses. Overall survival rates remain high after 5 years of follow-up, and historical comparisons with other treatments demonstrate improved overall survival with imatinib in the long term. Patients with accelerated-phase or blast-crisis CML, or those who have not responded to prior interferon-alpha therapy also benefit from imatinib treatment. Some patients become resistant or intolerant to imatinib therapy; management strategies to overcome these problems include dosage adjustment, other treatments, or combination therapy with imatinib and other agents. Allogeneic HSCT is currently the only potentially curative treatment, but it is associated with high rates of morbidity and mortality and is not suitable for all patients. The introduction of imatinib has had a marked impact on outcomes in patients with CML. It remains a valuable treatment for all stages of the disease, especially initial treatment of newly diagnosed Ph+ chronic-phase CML, and is endorsed by European and US treatment guidelines as a first-line option.

Usefulness of quantitative assessment of JunB gene expression as a marker for monitoring chronic myeloid leukemia patients undergoing imatinib therapy

JunB is a component of the activator protein 1 transcription factors and has been identified to be important in hematopoiesis. Transgenic mice lacking JunB expression develop myeloproliferative disease resembling human chronic myeloid leukemia (CML). JunB expression was significantly decreased in CML patients. We used real-time quantitative reverse transcription-polymerase chain reaction analysis to monitor both JunB and BCR-ABL expression during imatinib therapy. Nineteen patients were evaluated every 2 to 4 weeks, and their levels of JunB expression before therapy were significantly decreased compared with those of healthy individuals. After imatinib therapy, an increase in JunB expression was found in 5 patients, all of whom achieved a complete cytogenetic response (CCR) and molecular response (MR), with a decrease in BCR-ABL expression. JunB expression decreased to a very low level in 2 patients, both of whom showed progression to blast crisis. Variable JunB expression was found in the other 12 patients, and their outcomes were mostly driven by BCR-ABL levels. The patients with an increase in JunB expression were statistically more likely to achieve a major cytogenetic response (P = .045), CCR (P = .033), and MR (P = .033) than the group with no increase in JunB expression, and a durable response was observed. This study revealed that an increase in JunB expression is a good prognostic marker for predicting clinical response in CML patients treated with imatinib when such data are combined with an evaluation of BCR-ABL expression.

Rationale for the recommendations for harmonizing current methodology for detecting BCR-ABL transcripts in patients with chronic myeloid leukaemia

Molecular monitoring for patients with chronic myeloid leukaemia (CML) has become an important practice in the era of imatinib therapy. For successful widespread introduction into the mainstream patient monitoring schedule, many procedural aspects of the complex real-time quantitative polymerase chain reaction (RQ-PCR) technique for measuring BCR-ABL transcripts require optimization. Recommendations for harmonizing the differing methodologies have recently been proposed. These recommendations were designed to maximize reliability of analysis for clinical decision making and proposed the adoption of an International Scale of measurement. The purpose of this review is to present the evidence and supporting data for specific recommendations. These recommendations include use of the same source of cells, either blood or marrow, for analysis; for validation of equal PCR amplification efficiencies of cDNA and standards when using a plasmid to construct standard curves and for ensuring ongoing high-level performance by undertaking a quality assurance programme. Clinicians must know the measurement reliability of an RQ-PCR assay to be able to determine the significance of a change in BCR-ABL level. An assay with poor precision limits the clinical usefulness of results. International harmonization should establish RQ-PCR measurement of BCR-ABL as the best method for monitoring treatment response for patients with CML.

Monitoring CML patients responding to treatment with tyrosine kinase inhibitors: review and recommendations for harmonizing current methodology for detecting BCR-ABL transcripts and kinase domain mutations and for expressing results

The introduction in 1998 of imatinib mesylate (IM) revolutionized management of patients with chronic myeloid leukemia (CML) and the second generation of tyrosine kinase inhibitors may prove superior to IM. Real-time quantitative polymerase chain reaction (RQ-PCR) provides an accurate measure of the total leukemiacell mass and the degree to which BCR-ABL transcripts are reduced by therapy correlates with progression-free survival. Because a rising level of BCR-ABL is an early indication of loss of response and thus the need to reassess therapeutic strategy, regular molecular monitoring of individual patients is clearly desirable. Here we summarize the results of a consensus meeting that took place at the National Institutes of Health (NIH) in Bethesda in October 2005. We make suggestions for (1) harmonizing the differing methodologies for measuring BCR-ABL transcripts in patients with CML undergoing treatment and using a conversion factor whereby individual laboratories can express BCR-ABL transcript levels on an internationally agreed scale; (2) using serial RQ-PCR results rather than bone marrow cytogenetics or fluorescence in situ hybridization (FISH) for the BCR-ABL gene to monitor individual patients responding to treatment; and (3) detecting and reporting Philadelphia (Ph) chromosome-positive subpopulations bearing BCR-ABL kinase domain mutations. We recognize that our recommendations are provisional and will require revision as new evidence emerges.

Prediction of response to imatinib by prospective quantitation of BCR-ABL transcript in late chronic phase chronic myeloid leukemia patients

Imatinib mesylate (STI571), a specific Bcr-Abl inhibitor, has shown a potent antileukemic activity in clinical studies of chronic myeloid leukemia (CML) patients. Early prediction of response to imatinib cannot be anticipated. We used a standardized quantitative reverse-transcriptase polymerase chain reaction (QRT-PCR) for BCR-ABL transcripts on 191 out of 200 late-chronic phase CML patients enrolled in a phase II clinical trial with imatinib 400 mg/day. Bone marrow samples were collected before treatment, after 12, 20 and at the end of study treatment (52 weeks) while peripheral blood samples were obtained after 2, 3, 6, 10, 14, 20 and 52 weeks of therapy. The amount of BCR-ABL transcript was expressed as the ratio of BCR-ABL to beta2-microglobulin (beta2M). We show that, following initiation of imatinib, the early BCR-ABL level trends in both bone marrow and peripheral blood samples made it possible to predict the subsequent cytogenetic outcome and response. We propose this method as the method of choice for monitoring patients on imatinib therapy. QRT-PCR studies may be able to identify degrees of molecular response that predict both complete cytogenetic response and long term stability, as well as patterns of response that provide an early indication of relapse and imatinib resistance.

Limited clinical value of regular bone marrow cytogenetic analysis in imatinib-treated chronic phase CML patients monitored by RQ-PCR for BCR-ABL

Real-time quantitative polymerase chain reaction (PCR) for BCR-ABL mRNA in the peripheral blood (RQ-PCR) provides an accurate and reliable measure of response to therapy in chronic myeloid leukaemia (CML). We wanted to determine in what circumstances additional clinically relevant information was provided by simultaneous cytogenetic analysis in RQ-PCR monitored patients receiving imatinib treatment. We analysed 828 simultaneous RQ-PCR and bone marrow cytogenetic analyses from 183 patients with chronic phase CML with a median follow-up of 20 months. Cytogenetic progression was defined as Philadelphia (Ph)-positive clonal evolution, loss of complete cytogenetic response or an increase of > or = 20% Ph-positive cells. Cytogenetic progression occurred in 24/183 (13%) patients. At the time of cytogenetic progression, none of the 24 patients had a major molecular response (MMR; > or = 3-log reduction in BCR-ABL from standardised baseline). There were 320 RQ-PCR results from 95 patients indicating MMR. No abnormality was detected in any of the corresponding cytogenetic analyses. A policy of regular RQ-PCR monitoring with cytogenetic analysis targetted only to patients who have not achieved, or have lost MMR would represent a rational approach to monitoring and spare most patients the discomfort of multiple marrow aspirates. This approach depends upon availability of an accurate, reproducible RQ-PCR assay with ongoing quality assurance.

Role of JAK-STAT Signaling in the Pathogenesis of Myeloproliferative Disorders

The identification of JAK2V617F mutations in polycythemia vera (PV), essential thrombocytosis (ET), and myelofibrosis (MF) represents an important advance in our understanding of these myeloproliferative disorders (MPD). Most, if not all, patients with PV and a significant number of patients with ET and MF are JAK2V617F positive, and the mutation likely arises in the hematopoietic stem cell compartment. JAK2V617F is a constitutively active tyrosine kinase that is able to activate JAK-STAT signaling most efficiently when co-expressed with the erythropoietin receptor (EPOR), the thrombopoietin receptor (MPL), or the granulocyte colony-stimulating factor receptor (GCSFR). Data from murine models supports the central role of JAK2V617F in the pathogenesis of MPD, as expression of JAK2V617F in a bone marrow transplantation assay results in polycythemia and myelofibrosis in recipient mice. Activation of JAK-STAT signaling by JAK2V617F in some, but not all MPD patients with ET and MF led to the identification of the constitutively active MPLW515L allele in ET and MF. Small molecule inhibitors of JAK-STAT signaling are currently being developed, which offer potential for molecularly targeted therapy for patients with PV, ET, and MF. Despite these advances, many questions remain regarding the role of a single disease allele in three phenotypically distinct MPD, the potential clinical efficacy of JAK2 inhibitors, and the identity of oncogenic alleles in JAK2V617F/MPLW515-negative MPD.

Sustained complete molecular remissions after treatment with imatinib-mesylate in patients with failure after allogeneic stem cell transplantation for chronic myelogenous leukemia: results of a prospective phase II open-label multicenter study

PURPOSE

In the era of molecular therapy of chronic myelogenous leukemia (CML) applying BCR-ABL tyrosine kinase inhibitors, the usefulness of molecular end points, in particular, quantitative polymerase chain reaction (PCR) for BCR-ABL in monitoring responses has been broadly accepted. Therefore, we have designed a prospective phase II trial in CML, which, for the first time, evaluated the feasibility and safety of molecular end points as surrogate markers to guide through a stratified treatment algorithm within a multicenter trial.

PATIENTS AND METHODS

As a clinical model, we adopted minimal residual disease (MRD) found in relapse after allogeneic stem cell transplantation (SCT) in CML. Forty-four patients were enrolled and received the BCR-ABL tyrosine kinase inhibitor imatinib (IM) at a starting dose of 400 mg/d. The quality of molecular responses achieved then decided on discontinuation of IM or dose escalation up to 800 mg/d, and finally, on application of donor lymphocyte infusions. Results Seventy percent of patients achieved a complete molecular response (CMR), defined as nested PCR-negativity for BCR-ABL in three consecutive samples. Interestingly, in four out of 10 patients who discontinued IM, CMR was durable even after cessation of IM with a median follow-up of 494 days. This suggests the possibility of long-term tumor control in a subset of patients.

CONCLUSION

The treatment strategy showed that IM treatment was well-tolerated and highly efficacious in MRD after allogeneic SCT. Moreover, this study demonstrated that evaluation of a molecular end point within a multicenter trial can be a safe and effective tool for clinical decision making.

Early prediction of molecular remission by monitoring BCR-ABL transcript levels in patients achieving a complete cytogenetic response after imatinib therapy for posttransplantation chronic myelogenous leukemia relapse

Imatinib induces a high complete cytogenetic response (CCR) rate in relapsed chronic myelogenous leukemia. By analyzing minimal residual disease (MRD) under the levels of CCR, we tried to assess the molecular response after imatinib therapy. By using real-time quantitative reverse transcriptase-polymerase chain reaction (Q-RT-PCR), MRD was evaluated in 23 patients (3 in cytogenetic relapse, 6 in chronic phase, 9 in accelerated phase, and 5 in blast crisis) who were treated with standard-dose imatinib for relapsed chronic myelogenous leukemia after allogeneic stem cell transplantation. With a median therapy time of 399 days (range, 35-817 days), 19 (83%) patients achieved a CCR. Meanwhile, 11 (58%) of them achieved a molecular remission (MR), which was associated with improved survival. The Q-RT-PCR data were compared according to the best response (MR, n = 11; CCR, n = 8) in the patients achieving a CCR. The BCR-ABL/ABL ratios were similar in 2 groups at 3 months but were significantly different at 6 months (median, 0.0000012 for MR and 0.00022 for CCR; P =.003). The probability of a subsequent MR was significantly higher in patients with a lower BCR-ABL/ABL ratio at 6 months (100% for <0.0001 versus 33% for >/=0.0001; P =.006) or a greater reduction in the level between 3 and 6 months (log-reduction >/=1.0;, 100%; <1.0, 17%; P =.003). Q-RT-PCR is a reliable method for monitoring MRD: the early trends in the BCR-ABL/ABL ratio may be clinically useful in discriminating patients who will achieve an MR from those who will remain in CCR.

Molecular monitoring of BCR-ABL as a guide to clinical management in chronic myeloid leukaemia

Molecular monitoring of BCR-ABL transcript levels by real-time quantitative PCR is increasingly used to assess treatment response in patients with chronic myeloid leukaemia (CML). This has become particularly relevant in the era of imatinib therapy when residual levels of leukaemia usually fall below the level of detection by bone marrow cytogenetic analysis. Studies of imatinib-treated patients have determined that BCR-ABL levels measured early in therapy can predict subsequent response and the probability of acquired resistance. The defining of a molecular level of response that indicates a high probability of progression-free survival highlights the relevance of molecular analysis for clinical management. Small increases in the BCR-ABL level can identify patients with kinase domain mutations that lead to imatinib resistance. Therefore, these assays can be used as a screening strategy for mutation analysis. As second generation kinase inhibitors commence clinical trials, the molecular response will be a primary end-point that determines efficacy.

Cytogenetic testing for therapeutic indication in cancer

The association of cytogenetic abnormalities with cancer is well established. However, due to the historic lack of specific insight into the functional role of these anomalies, they have mostly served as diagnostic and/or prognostic indicators. Recent developments in chronic myelogenous leukemia and breast cancer have raised hopes for specific cytogenetic alterations to serve as therapeutic targets. This article reviews the aid provided by molecular diagnostics in these exciting developments in the cancer arena.