Response In Chronic Myeloid Leukemia Research Articles

Disease Knowledge In Chronic Myeloid Leukemia (CML) Patients as a Predictor of Compliance to Treatment.

AbstractAbstract 4481 Background:Tyrosine kinase inhibitors (TKIs) targeting the BCR-ABL fusion protein have greatly improved outcome of patients with CML. Despite this, some patients fail to respond or lose their initial response on continued treatment. Reasons for this are not completely understood and may include poor patient compliance. We developed a questionnaire (CML-Q) to explore patient knowledge of CML and its predictive value in compliance and response to treatment. Relationship of compliance with serum drug levels was also studied. Methods:Patients enrolled in the CML program at LAC+USC Medical Center were eligible. CML-Q included 42 questions addressing patient demographics (14%), prior knowledge of CML (7%), specifics about cause and pathogenesis of CML (5%), self-perceived compliance (5%), satisfaction regarding treatment and healthcare providers (19%) and quality of life (50%). Physician assessed patient compliance was determined separately. In patients currently on imatinib, serum drug trough levels were determined using commercially available laboratory testing. T-test and Fisher Exact test were used for statistical analysis with a 0.05 nominal significance level. Results:The CML-Q was administered to 80 patients. Of these, 39 responded while the rest either declined or were lost to follow up. Amongst the 39 evaluable patients (18 females; 46%, 21 males; 55%) median age was 47.5 yr (range 25–78) and median time since diagnosis was 34.1 mth (range 9–230). Majority of these (n=33; 84.6%) were on TKIs at the time of analysis. Four (11%) patients had received previous stem cell transplant for CML. Amongst the patients 19 (49%) were on first, 7 (18%) on second, 5 (13%) on third, 5 (13%) on fourth, 2 (5%) on fifth and 1 (2%) on seventh line treatment. Twenty-six patients (66%) responded to the Spanish version of CML-Q, while 13 (34%) responded in English. Responses to CML-Q were complete in 49% cases, while others had some skipped or erroneous responses. In such cases, the skipped or erroneous answers were withdrawn from final analysis while questions with complete and unambiguous responses were included. Patient compliance was classified as patient-perceived or physician-perceived. A kappa statistic between these two groups was 0.13, suggesting only slight agreement between the patient's own and the physician's assessment of compliance to treatment. Thus, for compliance-related analysis, patients were divided into true-compliant (TC) (patient-perceived and physician-perceived compliant) (42%) and non-compliant (NC) (reported non-compliant by the patient or physician or both) (58%) groups. There was a significant difference between TC and NC responses to the CML-Q regarding time since CML diagnosis (< or >3 yr, respectively) (p=0.04), specific questions addressing compliance to medications (p=0.002) and those addressing treatment staff's explanation of the effects of treatment (p=0.01). In a subset of patients taking imatinib (n=20; TC=10, NC=10), serum trough imatinib levels were evaluated. There was no statistically significant difference between the mean serum imatinib trough level of TC (1448 ng/ml) and NC (1321 ng/ml) groups (p=0.99). Response to treatment for all patients was classified as optimal or suboptimal based on established CML response milestones. In the TC group 94% patients had optimal responses while 76% patients had optimal responses within the NC group. This was not statistically significant (p=0.19). Conclusions:There is limited data on factors that may affect treatment compliance in CML patients, and ultimately may dictate efficacy of therapeutic interventions. Using an extensive CML questionnaire, we observed that compliance may be perceived differently by patients and healthcare providers. Specific questions regarding treatment adherence were able to differentiate TC and NC groups. Patients were more likely to comply if they were aware of the treatment effects, as explained by healthcare personnel. There was no significant association between compliance and serum imatinib levels. NC patients were more likely to have a CML diagnosis for >3 yrs, suggesting that patient education should be reinforced with continued treatment. Although not statistically significant, compliant patients more often had optimal response to treatment. Our results suggest that patient compliance to treatment in CML should be further evaluated in larger cohorts prospectively. [Display omitted] [Display omitted] Disclosures:No relevant conflicts of interest to declare.

Monitoring molecular response in chronic myeloid leukemia

Before the advent of tyrosine kinase inhibitor (TKI) therapy, the evaluation of hematologic and cytogenetic responses was sufficient to gauge treatment efficacy in patients with chronic myeloid leukemia. However, with more potent TKI therapies, the majority of patients achieve complete cytogenetic response. Furthermore, deeper molecular responses are now commonly achieved, necessitating a reliance on molecular monitoring to assess residual leukemic disease. The prognostic significance between molecular responses and duration of complete cytogenetic response, progression-free survival, and event-free survival is described herein. A discussion of the concept of complete molecular response is also provided, and the potential for imatinib treatment discontinuation is evaluated. The implications of rising BCR-ABL1 transcript levels and caveats of molecular monitoring are also described.

The poor response to imatinib observed in CML patients with low OCT-1 activity is not attributable to lower uptake of imatinib into their CD34+ cells

AbstractThe functional activity of the organic cation transporter 1 (OCT-1) protein in chronic myeloid leukemia (CML) mononuclear cells (MNCs) is highly predictive of molecular response in imatinib treated patients. Here we investigate whether the MNC OCT-1 activity (OA) provides a surrogate indicator of effective targeting of the more immature CD34+ cells. While confirming our previous findings that high MNC OA is significantly associated with the achievement of major molecular response (MMR; P = .017), the present studies found no relationship between high CD34+ OA and the achievement of MMR. Furthermore, no correlation was found between the MNC OA and the CD34+ OA in matched CML samples. These results suggest that the predictive value of the MNC OA may primarily reflect the effective targeting and subsequent reduction of mature CML cells. Therefore kinase inhibition in these mature cells, and not the CD34+ cells, may be the key determinant of response in CML.

Reply to V. Pitini et al

We appreciate the comments by Pitini et al highlighting the interesting mechanisms of action of interferon alfa (IFN) that supplement the activity of tyrosine kinase inhibitors in the treatment of chronic myeloid leukemia (CML). As monotherapy, IFNinduces heterogeneous responses in CML, with up to 80% of early chronic-phase patients achieving hematologic remission but only 8% to 30% achieving complete cytogenetic remission. Although response correlates with Euro and Sokal risk scores, the molecular basis for heterogeneous responses and indeed more broadly the mechanism of response to IFNremain poorly understood. Recent evidence suggested that IFNmay sensitize dormant stem cells to imatinib-induced apoptosis by inducing their cell cycle entry. This observation, which was discussed in our report, was made using short courses of high-dose IFNfollowed by fluorouracil in a non-CML mouse model. Hematopoietic stem cells (HSCs) respond to IFNtreatment by the increased phosphorylation of STAT1 and PKB/Akt, the expression of IFN target genes, and the upregulation of stem cell antigen-1 (Sca-1). In HSCs lacking the IFN/ receptor, STAT1 and Sca-1 are insensitive to IFN stimulation. Conversely, HSCs chronically activated by IFN are rapidly outcompeted in repopulation assays. Whereas chronic activation of the IFN pathway in HSCs impairs their function, acute IFN treatment promotes the proliferation of dormant HSCs in vivo. The anti-CML mechanism exerted by IFN has classically been linked to the effects on immune cells, including cytotoxic T cells. In our study, patients were predominantly treated with pegylated IFN-2a in low doses, which results in a continuous exposure of normal and neoplastic cells to the drug. Although an additional stem-cell activation effect of permanent IFNadministration cannot be excluded, the effect should have disappeared after chronic administration during maintenance therapy. Thus, for the concept of maintenance therapy with IFNafter tyrosine kinase inhibitor induction, the stimulation effect on cytotoxic T cells is the dominant cause of response, which persists even after discontinuation of all therapy including IFN. Because the model by Essers et al suggests a new mode of action of IFN in cancer therapy, the appropriate demonstration of applicability to CML in vivo is pending. Our data suggest the predominance of an immunophenomenon, which will persist even after discontinuation of IFN. Beginning CML therapy with IFNfollowed by imatinib therapy was tested in the pilot phase of the German CML Study IV. This schedule will be able to test for the stem cell recruiting activity of IFN, which will be used to increase the efficacy of tyrosine kinase inhibitors.

Complete molecular response in CML after p210 BCR–ABL1-derived peptide vaccination

A 63-year-old woman with chronic myeloid leukemia (CML) received treatment with interferon (IFN)-α for 6 years. After achieving a complete cytogenetic response that was repetitively documented, IFN-α treatment was stopped. Despite maintenance of a complete cytogenetic response, a progressive rise of the BCR-ABL1 transcript was detected and loss of major molecular response occurred about 2 years after stopping IFN-α therapy. Disease remained at molecular level. Peripheral blood quantitative real-time PCR every 3 months and periodical bone marrow aspirate were performed to monitor disease. Chronic-phase, Philadelphia-positive CML that was still detectable after complete cytogenic response 2 years after cessation of IFN-α therapy. The patient was treated with a target immune approach receiving a therapeutic vaccine that consisted of an immunogenic 25-mer b2a2 breakpoint-derived peptide (CMLb2a2-25) with binding properties for several HLA-DR molecules. After nine boosts of vaccine the patient developed an adequate b2a2-25 peptide-specific CD4(+) T-cell response and BCR-ABL1 transcript started to decline in peripheral blood. No hematological or extrahematological effects were documented during therapy. At the last evaluation, 39 months since vaccinations commenced, the patient is in complete molecular response with an undetectable level of BCR-ABL1 transcript both in peripheral blood and in bone marrow and she continues to receive boosts of vaccine every 3 months as the only treatment.

Expression, epigenetic regulation, and humoral immunogenicity of cancer-testis antigens in chronic myeloid leukemia

ObjectiveCancer-testis (CT) antigens represent attractive targets for tumor immunotherapy based on their tumor-restricted expression and immunogenicity. However, a broad picture of the expression of CT antigens and associated humoral immune responses in chronic myeloid leukemia (CML) is still missing. MethodsWe screened CML cell lines and bone marrow (BM) samples from healthy donors by RT-PCR for the expression of 31 CT antigens before and after treatment with epigenetic agents. Expression of tumor-restricted antigens was further examined in 60 CML patients and humoral immune responses against 15 CT antigens were screened by ELISA. ResultsIn untreated cell lines we detected the expression of 17 CT antigens that were absent from normal BM. Expression of most antigens increased following demethylating treatment with 5′-Aza-2′-Deoxycytidine. In these samples, only PRAME was repeatedly detected and expression correlated with several clinicopathological parameters and decreased overall survival. We further show that a lower frequency of PRAME-positive samples during imatinib treatment was not caused by gene-specific downregulation. Analyzing the patients’ antibody responses we found that the vast majority of patients lacked spontaneous immunity against CT antigens including PRAME. ConclusionsCT antigen expression can be increased by the application of epigenetic agents and the expression of PRAME correlates with clinicopathological parameters and overall survival in patients with CML, but does not lead to humoral immune responses. PRAME-specific immunotherapy might represent a promising approach for the eradication of residual therapy-resistant leukemic cells due to its frequent expression and stability under imatinib treatment.

Multidrug resistance gene (MDR1) polymorphisms correlate with imatinib response in chronic myeloid leukemia

The human multidrug resistance gene (MDR1, ABCB1) codes for P-glycoprotein (P-gp) that affects the pharmacokinetics of many drugs. MDR1 single nucleotide polymorphisms (SNPs) are associated with drug clearance. Imatinib is a substrate of P-gp-mediated efflux. We investigated the MDR1 T1236C, G 2677T/A, and C3435T polymorphism in 52 patients with chronic myeloid leukemia treated with imatinib. The distribution of MDR1 1236, 2677, or 3435 genotypes was significantly different between the resistance patients and sensitivity patients. The resistance incidence correlated with the number of T alleles at locus 1236 and 3435. Resistance was higher for patients homozygous for the 1236T allele when compared to patients with CT/CC genotype groups (75% vs. 31.3%, P = 0.004). For the G2677T/A polymorphism, a better complete cytogenetic remission was observed for patients with genotype AG/AT/AA, when compared to other genotype groups (TT/GT/GG, P = 0.02). Patients with 3435 TT/CT genotypes showed a higher resistance when compared with patients with CC genotype (59.4% vs. 25%, P = 0.023). In conclusion, determination of 1236T, C3435T, and G2677T MDR1 polymorphisms might be useful in response prediction to therapy with imatinib in patients with CML.

Sperm associated antigen 9 expression and humoral response in chronic myeloid leukemia

Early diagnosis and cure for patients with chronic myeloid leukemia (CML) exhibit significant clinical challenges because of the disease progression from chronic phase (CP) into a rapidly fatal blast crisis. Our earlier studies suggested an association of sperm associated antigen 9 (SPAG9) with various human malignancies. The present investigation revealed that SPAG9 mRNA and protein are expressed in CML patients (88%), in K562 and KCL-22 cells. Further, SPAG9 protein expression was also detected on cell surface suggesting that this molecule may be a suitable target for immunotherapy. Interestingly, 90% CML-CP patients showed humoral response against SPAG9, suggesting its important role in early diagnostic of CML-CP. Further investigation is warranted in establishing the potential of SPAG9 as a biomarker and immunotherapeutic target for early treatment of CML-CP patients.

Failure of copy Imatib (CIPLA, India) to maintain hematologic and cytogenetic responses in chronic myeloid leukemia in chronic phase

A 50-year-old woman presented with CML-CP and was initially treated with branded imatinib (Glivec) 400 mg/day. She rapidly achieved a complete hematologic response (CHR), at which point she switched therapy to a copy version of imatinib (Imatib). She received 400 mg/day of Imatib for 3 months, during which time her platelet count decreased from 250 x 10(9) to 105 x 10(9)/L and her hemoglobin count fell from 12.8 to 11 g/dL. The patient's total leukocyte count rose rapidly from 4 x 10(9) to 70 x 10(9)/L, and the CHR was lost. At this point, therapy was switched back to Glivec at 400 mg/day, and the CHR was rapidly regained. Furthermore, the patient achieved a major cytogenetic response by 6 months after reintroduction of Glivec. This case report suggests a difference in clinical efficacy between the authorized form of imatinib (Glivec) and the copy version of the drug (Imatib). The exact reasons for the observed difference in clinical efficacy are unknown, but likely relate to the use of alternative polymorphic forms of the drug. Glivec can be obtained directly from the manufacturer (Novartis Pharmaceuticals) through a variety of patient access programs that should be fully explored when needed.

A polymorphism associated with STAT3 expression and response of chronic myeloid leukemia to interferon

Interferon alpha (IFN) induces variable responses in chronic myeloid leukemia (CML), with 8-30% of early chronic phase cases achieving a complete cytogenetic response. We hypothesized that polymorphic differences in genes encoding IFN signal transduction components might account for different patient responses. We studied 174 IFN-treated patients, of whom 79 achieved less than 35% Philadelphia-chromosome (Ph) positive metaphases (responders) and 95 failed to show any cytogenetic response (more than 95% Ph-positive metaphases; non-responders). We compared 17 single nucleotide polymorphisms (SNPs) at IFNAR1, IFNAR2, JAK1, TYK2, STAT1, STAT3 and STAT5a/b between the two groups and found a significant difference for rs6503691, a SNP tightly linked to STAT5a, STAT5b and STAT3 (minor allele frequency 0.16 for non-responders; 0.06 for responders, P=0.007). Levels of STAT3 mRNA correlated with rs6503691 genotype (P<0.001) as assessed by real time quantitative PCR and therefore we conclude that rs6503691 is associated with the STAT3 expression levels and response of CML patients to IFN.

Persistence of derivative chromosome 22 after achieving a major molecular response in chronic myeloid leukemia with a cryptic BCR-ABL1 fusion gene

We herein report the findings of a 47-year-old Japanese female with chronic myeloid leukemia (CML) with a cryptic BCR-ABL1 transcript on chromosome 9 and a derivative chromosome 22 unrelated to BCR-ABL1. Although she achieved and continued to demonstrate a major molecular response to imatinib treatment following interferon-alpha, there was persistence of a derivative chromosome 22. A detailed chromosome/molecular studies, including serial karyotyping analysis, finally resulted in the karyotyping at the disease onset to be 47,XX,+del(22)(q11.2), with two genetic evens, namely a cryptic BCR-ABL1 transcript on chromosome 9 and derivative chromosome 22 unrelated to BCR-ABL1. This CML case with these two rare genetic events thus raises diagnostic issues such as the difficulty in making a concise evaluation of the chromosomal/molecular events and an accurate disease prognosis, as well as the difficulty in determining the disease remission status after treatment.

Imatinib Plasma Levels and Its Correlation with Response in Chronic-Phase Chronic Myeloid Leukemia: Experience of One Centre.

Abstract 4284 IntroductionImatinib (IM), 400 mg/d. induces durable responses in chronic myeloid leukaemia (CML) in chronic phase (CP). However, although IM-biodisponibility is fairly good, its plasma levels are variable and can not be predicted. Recently, these plasma concentrations have been related both to the dose being administrated and to the cytogenetic and molecular responses. Thus, Imatinib pharmacokinetics could be an issue towards treatment optimisation in CML patients. Recent studies suggest that therapeutic IM plasma levels should be above 1040 ng/dl. AimsTo evaluate the association between IM dose and throughout plasma levels with different clinical outcomes. ResultsIn this study, we looked for an association between plasma concentrations and clinical outcomes in 16/86 CML chronic phase patients who did not achieve optimal responses following the European Leukemia Net guidelines (ELN) (table 1). Patients with optimal responses and treated with the same standard doses were also analysed as a control group. Patients receiving doses above 400 mg showed throughout plasma levels considered as appropriate. In 7 of 16 patients (47.5%) not achieving optimal responses (ELN criteria), plasma levels were below the supposed therapeutic ranges. We have found no evidence for a correlation between clinical risk factors at diagnosis and the measurement of optimal plasma levels. ConclusionsIM plasma levels are well correlated with IM dose administrated in the patients studied. In almost 50% of patients who did not achieve optimal responses, IM plasma levels were under the ranges considered therapeutic. Probably these are the patients who may benefit of a dose increase. Obviously, to learn more about the practical value of these measurements a longer follow up with a larger number of patients is needed.IMATINIB RESPONSEIMATINIB DOSESIMATINIB PLASMA LEVELS (ng/dl)MUTATIONS1SUBOPTIMAL400733NO2SUBOPTIMAL8001600NO3SUBOPTIMAL4003490NO4SUBOPTIMAL400853YES5SUBOPTIMAL4002142NO6SUBOPTIMAL400899NO7SUBOPTIMAL4002328NO8SUBOPTIMAL400661NO9SUBOPTIMAL400282NO10SUBOPTIMAL4002208NO11SUBOPTIMAL6001090NO12SUBOPTIMAL4002967NO13SUBOPTIMAL4004221NO14SUBOPTIMAL6001030NO15SUBOPTIMAL4002321NO16SUBOPTIMAL4001469NO Disclosures:No relevant conflicts of interest to declare.

Targeting Isoprenylcysteine Carboxyl Methyltransferase to Overcome Resistance and Improve Responses in Chronic Myeloid Leukemia.

Abstract 3273Poster Board III-1A strategy to overcome resistance of chronic myeloid leukemia (CML) to Bcr-Abl tyrosine kinase inhibitors (TKI) is by targeting alternative pathways. Increasing evidence suggests that activation of the Ras family of small GTPases is important in leukaemogenic transformation by Bcr-Abl. Ras and Rho GTPases play important roles in the initiation and progression of cancer by disrupting the normal regulation of specific intracellular signalling pathways, promoting cell cycle progression and resistance to apoptosis. The biological function of Ras and Rho GTPases is, to a large extent, dependent on prenylation, a three-step post-translational modification process. The first step is catalysed by farnesyl transferase or geranylgeranyl transferase and the final step is catalysed by isoprenylcysteine carboxyl methyltransferase (Icmt). We have found inhibition of Icmt by a novel selective inhibitor, cysmethynil, enhanced the anti-proliferative effect of imatinib in CML cell lines. The combination of cysmethynil and imatinib was synergistic in inducing apoptosis in the imatinib-sensitive K562 and Bafp210 CML cell lines and apoptosis was further increased when the drugs were given sequentially, with cysmethynil added after imatinib. This combination was also effective in the imatinib-resistant Bcr-Abl- and P-glycoprotein-overexpressing LAMA84 cell line. The synergy was also observed when cysmethynil was combined with dasatinib in both the imatinib-sensitive Bafp210 and imatinib-resistant Bafp210 Y253F mutant but not in the Bafp210 T315I mutant cell lines. The combination therapy was more effective than single agent in inducing apoptosis in treatment-naive primary CML CD34+ cells and was not toxic to cord blood CD34+ cells (Figure 1). [Display omitted] Imatinib decreases p-CrkL through its inhibition of Bcr-Abl kinase. Interestingly, in both K562 and Bafp210, cysmethynil also decreases p-CrkL and when combined with imatinib, p-CrkL levels are reduced further (Figure 2). CrkL activation is dependent on a multimeric protein complex containing PI-3 kinase, docking protein 2, CrkL, Vav and the Rho GTPase, Rac. We hypothesise that inhibition of CrkL phosphorylation in the CML cell lines by cysmethynil is through the inhibition of Rac prenylation. This may be responsible for the synergistic activity observed when cysmethynil is combined with imatinib. In conclusion, our preliminary results suggest that the combination of a Bcr-Abl TKI and an Icmt inhibitor exerts a selective apoptotic effect in CML cells and this combination should be explored further as a useful tool to overcome resistance and improve responses in CML. [Display omitted] Disclosures:Druker:MolecularMD: Equity Ownership; Novartis Pharmaceuticals: ; Bristol-Myers Squibb:.

Blocking of Cytokine Survival Signals along with Intense Bcr-Abl Kinase Inhibition May Eradicate CML Progenitor Cells.

Abstract 3250Poster Board III-1▪▪This icon denotes an abstract that is clinically relevant.Preclinical studies of imatinib set the paradigm of continuous Bcr-Abl kinase inhibition for optimal response in chronic myeloid leukemia (CML). However, the clinical success of once daily dasatinib, despite its short serum half life, implies that intermittent inhibition of Bcr-Abl kinase activity is sufficient for clinical response. In vitro studies also demonstrated that short-term intense (≥90%) Bcr-Abl kinase inhibition triggers cell death in BCR-ABL + cell lines, demonstrating their oncogene addiction. However, the effect of short-term intense kinase inhibition on CD34+ CML progenitors is not studied. Clinical, mathematical modelling and in vitro studies suggest that leukemic stem cells (LSC) are difficult to eradicate and hence the majority of CML patients may not be cured with tyrosine kinase inhibitors (TKI). Inadequate Bcr-Abl kinase inhibition has been postulated to cause refractoriness of LSC to TKI's. This may be due to increased expression of ABCB1 and ABCG2 efflux proteins, or the quiescent state of LSC. However, the phenomenon could be independent of Bcr-Abl kinase activity. In vivo leukemic progenitors live in a cytokine rich environment which may be providing a mechanism for Bcr-Abl independent resistance. We have assessed the impact of short-term intense Bcr-Abl kinase inhibition on CML cell lines and CML CD34+ primary cells in the presence and absence of cytokines. In CML cell lines, short-term (cells were cultured with dasatinib for 30 min and following thorough drug washout, cells were recultured in drug free media for 72 hr) intense Bcr-Abl kinase inhibition with 100 nM dasatinib triggers cell death. In CML-CD34+ cells 30 min of culture with 100 nM dasatinib (n=13) or 30 μM IM (n=7) reduced the level of p-Crkl (surrogate marker of Bcr-Abl kinase activity) by 97±3% and 96±4% respectively. In the presence of either a six growth factors cocktail (6-GF; n=10) or GM-CSF (n=11) or G-CSF (n=4) alone, despite 97% inhibition of p-Crkl, short-term culture with 100 nM dasatinib (D100ST) reduced colony forming cells (CFC) by only 24%, 32% or 5%, respectively. However without cytokines, D100ST reduced CML-CD34+ CFCs by 70%. Consistent with the results observed with dasatinib, short-term culture with 30 μM imatinib (IM) (n=3) also reduced 90% CFC in the absence of cytokines but by only 38% in the presence of 6-GF. These results suggest that in CML-CD34+ cells, GM-CSF, G-CSF or 6-GF mediate Bcr-Abl independent TKI resistance. It is possible that cytokines may be promoting cell survival via signalling pathways that are refractory to dasatinib. To examine this possibility, we assessed the effect of D100ST on p-STAT5 signalling in CML-CD34+ cells, in the presence and absence of GM-CSF, G-CSF or 6-GF. STAT5 was constitutively phosphorylated in CML-CD34+ cells, and in the absence of cytokines, D100ST reduced the p-STAT 5. STAT5 phosphorylation was not inhibited by D100ST when cells were cultured with 6-GFs or GM-CSF however, the combination of D100ST and a Janus kinase (Jak) inhibitor dramatically reduced p-STAT5. Similarly, in the presence of GM-CSF (32.35±5.16% vs. 68.33±14.90%) or G-CSF (58.13±13 vs. 94.68±21.12) combination of D100ST and JAK inhibitor significantly reduced CFC compared to D100ST only. Thus our data suggest that in contrast to CML cell lines, primary CML progenitors may not be completely dependent on the BCR-ABL oncogene and that activation of the cytokine mediated JAK-2/STAT-5 pathway may circumvent the need for BCR-ABL signalling for maintenance of survival. Thus a therapeutic strategy based on short-term intense kinase inhibition may have limited success unless critical redundant cytokine-induced survival pathways are also inhibited. We postulate that blockade of cytokine signalling along with short-term intense Bcr-Abl kinase inhibition with a potent second generation TKI may provide a novel strategy to eradicate primitive CML cells. [Display omitted] Disclosures:White:Novartis and Britol-Myers Squibb: Research Funding. Hughes:BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding.

8501 Larynx preservation using induction chemotherapy followed by radiation – five-year evaluation of swallowing and laryngeal functions for patients enrolled in the GORTEC 2000–01 randomized study

Chronic myeloid leukemia (CML) is associated to the BCR-ABL1 oncogene and can successfully be treated with tyrosine kinase inhibitors (TKIs). However, it remains still under investigation which molecular factors may influence CML risk or varying responses to TKIs. The aim of this study was to assess the role of Glutathione-S-transferases (GSTs) genetic polymorphisms in CML susceptibility and TKI clinical outcome.Deletion polymorphisms in GSTM1 and GSTT1 genes and the single nucleotide polymorphism in GSTP1 c.319A > G (rs1695; p.105Ile > Val) were genotyped by PCR methods in 141 CML treated patients and 141 sex- and age-matched healthy individuals.Individual analysis of each GST gene showed no association with CML risk. A trend toward significance (p = 0.07) for a recessive model was found for GSTP1 (OR: 2.04; CI: 0.94-4.4). However, the combined analysis showed that GSTM1-null/GSTP1-GG as well as GSTT1-null/GSTP1-GG were associated with CML development (p = 0.03; OR: 3.54 CI: 1.2-14.57; p = 0.05; OR: 12.65; CI: 1.17-21.5). The relationship with treatment outcome showed that the presence of GSTM1 gene was significantly linked with an inferior rate of major molecular response (p = 0.048) and poor event free-survival (EFS) (p = 0.02). Furthermore, a group of patients with GSTP1-GG genotype were significantly associated with reduced EFS comparing to those carrying other GSTP1 genotypes (p = 0.049). GSTP1-GG genotypes had short time to treatment failure in a group of patients unresponsive to TKIs comparing to other GSTP1 genotypes (p = 0.03).This study highlights the significance of GSTM1 and GSTP1 polymorphisms on CML susceptibility and response to TKIs in the Argentinean population.

Monitoring chronic myeloid leukemia (CML) response to tyrosine kinase inhibitors (TKI) and homoharringtonine (HHT) using peripheral blood (PB) fluorescence in situ hybridization (FISH) and quantitative RT-PCR (Q-PCR): Are bone marrow biopsies still needed?

7064 Background: The purpose of this study is to compare simultaneously obtained PB and bone marrow (BM) BCR-ABL FISH and Q-PCR to monitor response to TKI and HHT in CML. Methods: Between January 2005 and December 2008, 52 patients (pts) with chronic (n = 37, 80%), accelerated (n = 6, 7%), and blast phase (n = 9, 14%) CML had 112 simultaneous PB and BM FISH and Q-PCR before and/or after start of imatinib (IM, n = 27), dasatinib (n = 9), nilotinib (n = 1), bosutinib (n = 13), or HHT (n = 2) for newly diagnosed (n = 27), IM resistant (n = 20), or IM intolerant (n = 5) CML. 13 (26%) had chromosomal abnormalities in addition to the Philadelphia chromosome, and 10 (20%) had a detectable BCR-ABL mutation including the T315I in 2 pts. Results: 24 (46%) had simultaneous PB and BM FISH and/or Q-PCR measurements obtained at 1 time point, 9 (17%) at 2; 9 (17%) at 3; 10 (20%) at &gt; 4 time points before and/or post-initiation of TKI or HHT. Excellent concordance was observed between PB and BM at all time points for both FISH (r = 0.96; p = 0.0003) and Q-PCR (r = 0.88; p= 0.0015). Correlation was not affected by the presence of additional chromosomal abnormalities, phase of the disease, treatment (TKI or HHT), or the number of prior therapies. Conclusions: FISH and Q-PCR are reliable methods to monitor CML response to TKI and HHT in patients with CML and may render the need for BM biopsy monitoring obsolete. No significant financial relationships to disclose.

Correlation between trough imatinib plasma concentration and clinical response in chronic myeloid leukemia

Correlation between trough imatinib plasma concentration and clinical response in chronic myeloid leukemia

Targeted treatment of chronic myeloid leukemia: role of imatinib.

Chronic myeloid leukemia (CML) is a myeloproliferative disorder characterized by clonal expansion of pleuripotent hematopoetic stem cells. The incidence of CML is 1 to 2 cases per 100,000 people per year; in the Western Hemisphere, CML accounts for 15% of leukemias in adults. Discovery of the specific karyotypic abnormality of the Philadelphia (Ph) chromosome in the pathogenesis of CML has led to a better understanding of the disease and hence to an advancement of targeted therapeutics. Availability of imatinib as an accepted targeted therapy in newly diagnosed patients has changed the treatment paradigm in CML. The majority of CML patients in chronic phase achieve excellent and durable responses with standard-dose imatinib. Mechanisms of primary and secondary resistance to imatinib in CML have been extensively studied and newer tyrosine kinase inhibitors are now being evaluated for clinical use. It is important that at any time the CML treatment and response remain optimal and thus patients on imatinib require continuous monitoring for early detection of resistance. This review will discuss the treatment and guidelines for monitoring CML patients in the imatinib era.

Suboptimal responses in chronic myeloid leukemia: milestones and mechanisms

Patients with chronic myeloid leukemia who fail to achieve timely treatment responses have a worse prognosis. Although many patients respond well to first-line treatment with imatinib, a significant proportion relapse or experience an inadequate response. Since effective alternative Bcr-Abl inhibitors are available (i.e., dasatinib or nilotinib), several regional groups have proposed milestones for imatinib failure or suboptimal response based on the achievement of specified levels of response within a defined treatment duration. A suboptimal response indicates that, although patients may continue to receive a benefit from continuing imatinib treatment at the assigned dose, long-term outcome may be better with an alternative strategy. The underlying mechanisms behind suboptimal responses are multifactorial and may differ from those causing relapse.

Role of gene-expression profiling in chronic myeloid leukemia

Gene-expression profiling enables disease classification and risk stratification, and provides important insights into possible pathogenetic mechanisms. The clinical management and prognosis of chronic myeloid leukemia (CML) has substantially changed after the introduction of targeted therapies, such as imatinib and the second-generation tyrosine kinase inhibitors nilotinib and dasatinib. Although exact characterization of CML pathogenetics has been performed by showing the causal pathogenetic relevance of the reciprocal translocation between chromosomes 9 and 22 for CML development, the disease still exhibits a marked clinical and biological heterogenicity. Thus, prognostic scores for a more exact disease classification, as well as for prediction of response to tyrosine kinase inhibitor therapy are warranted, especially because scores established within the interferon era have lost their prognostic value when applied to patients treated with imatinib. Gene-expression profiling has been proven to represent a powerful tool for early identification of nonresponders to cancer therapy. Several profiling studies in CML have been reported thus far. However, the available data are inconsistent, which is mainly due to technical reasons, such as the use of various different chips, different biostatistical algorithms for data analysis and, most importantly, the use of various different cellular sources (i.e., mononuclear cells from peripheral blood, whole bone marrow cells or selected bone marrow-derived stem/progenitor cells). This review will summarize the recent literature on gene-expression profiling for CML classification and response prediction.