ALBERT

Beschreibung: Abstract LBA-1 Background: Nilotinib is a highly potent and the most selective inhibitor of BCR-ABL, the only proven molecular target for CML therapy. ENESTnd (Evaluating Nilotinib Efficacy and Safety in Clinical Trials-Newly Diagnosed Patients) is a phase 3, randomized, open-label, multicenter study comparing the efficacy and safety of 300 or 400 mg bid nilotinib with 400 mg qd imatinib in patients (pts) with newly diagnosed Ph+ CML in chronic phase (CML-CP). Methods: 846 pts with newly diagnosed Ph+ CML-CP, diagnosed within 6 mos, and stratified by Sokal risk score, were randomized 1:1:1 to nilotinib 300 mg bid (n=282), nilotinib 400 mg bid (n=281), and imatinib 400 mg qd (n=283) arms. The primary endpoint was rate of major molecular response (MMR) at 12 months (mos). All pts had a minimum of 12 mos of treatment or discontinued early; median follow-up was 14 mos. MMR was defined as a value of ≤ 0.1% of BCR-ABL/ABL ratio on the International Scale. Molecular response was assessed by RQ-PCR at baseline, monthly for 3 mos and every 3 mos thereafter. Samples were analyzed at a central PCR laboratory. The major secondary endpoint was rate of complete cytogenetic response (CCyR) by 12 mos based on bone marrow cytogenetics. Results: Baseline demographics, disease characteristics, and Sokal scores were well balanced among the 3 arms; pts with high-risk Sokal scores were 28% in all arms. Median dose intensities of nilotinib delivered were 592 mg/day for 300 mg bid and 779 mg/day for 400 mg bid; imatinib dose intensity was 400 mg/day. Overall, 84%, 82%, and 79% of pts remained on the study for 300 mg bid nilotinib, 400 mg bid nilotinib, and 400 mg qd imatinib, respectively. Rates of MMR at 12 mos (Table) were superior for nilotinib 300 mg bid compared with imatinib 400 mg qd (44% vs. 22%,P 〈 .0001) and also for nilotinib 400 mg bid compared with imatinib 400 mg qd (43% vs. 22%,P 〈 .0001). Median time to MMR among pts who achieved MMR was faster for nilotinib 300 mg bid (5.7 mos) and nilotinib 400 mg bid (5.8 mos) compared with imatinib 400 mg qd (8.3 mos). Rates of CCyR by 12 mos were significantly higher for both nilotinib at either 300 mg bid compared with imatinib 400 mg qd (80% vs. 65%,P 〈 .0001) and for nilotinib 400 mg bid compared with imatinib 400 mg qd (78% vs. 65%,P = .0005). Overall, progression to advanced disease was lower for nilotinib 300 mg bid (2 pts) and nilotinib 400 mg bid (1 pt) compared with imatinib 400 mg qd (11 pts). Overall, both drugs were well-tolerated. Rates of discontinuation due to adverse events or laboratory abnormalities were 7% for nilotinib 300 mg bid, 11% for nilotinib 400 mg bid, and 9% for imatinib 400 mg qd. Pts were monitored for QT prolongation and LVEF. No patients in any treatment arm showed a QTcF interval 〉 500 msec. There was no decrease from baseline in mean LVEF anytime during treatment in any arm. The study is ongoing. Conclusions: Nilotinib at both 300 mg bid and 400 mg bid induced significantly higher and faster rates of MMR and CCyR compared with imatinib 400 mg qd, the current standard of care in pts with newly diagnosed CML. Nilotinib was effective across all Sokal scores. After only one year of treatment, both nilotinib arms resulted in a meaningful clinical benefit compared to imatinib, with reduction of transformation to AP/BC. Nilotinib exhibited a favorable safety and tolerability profile. The superior efficacy and favorable tolerability profile of nilotinib compared with imatinib suggests that nilotinib may become the standard of care in newly diagnosed CML. Disclosures: Saglio: Novartis: Consultancy, Speakers Bureau; BMS: Consultancy, Speakers Bureau. Off Label Use: Nilotinib is not currently approved for first-line treatment of CML. The presentation will report the results from a randomized study of imatinib versus nilotinib in patients with newly diagnosed Ph+ CML-CP. Kim:Novartis: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; BMS: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Wyeth: Research Funding. le Coutre:Novartis: Honoraria, Research Funding; BMS: Honoraria. Reiffers:Novartis: Research Funding. Pasquini:Novartis: Consultancy, Membership on an entity’s Board of Directors or advisory committees; BMS: Membership on an entity’s Board of Directors or advisory committees; Schering: Membership on an entity’s Board of Directors or advisory committees. Clark:Novartis: Honoraria, Research Funding, Speakers Bureau. Hughes:Novartis: Honoraria, Research Funding; BMS: Honoraria, Research Funding. Hochhaus:Novartis: Research Funding. Gallagher:Novartis: Employment, Equity Ownership. Hoenekopp:Novartis: Employment. Dong:Novartis: Employment, Equity Ownership. Haque:Novartis: Employment. Larson:Novartis:

Beschreibung: Dasatinib is a BCR-ABL inhibitor with 325-fold higher potency than imatinib against unmutated BCR-ABL in vitro. Imatinib failure is commonly caused by BCR-ABL mutations. Here, dasatinib efficacy was analyzed in patients recruited to phase 2/3 trials with chronic-phase chronic myeloid leukemia with or without BCR-ABL mutations after prior imatinib. Among 1043 patients, 39% had a preexisting BCR-ABL mutation, including 48% of 805 patients with imatinib resistance or suboptimal response. Sixty-threedifferent BCR-ABL mutations affecting 49 amino acids were detected at baseline, with G250, M351, M244, and F359 most frequently affected. After 2 years of follow-up, dasatinib treatment of imatinib-resistant patients with or without a mutation resulted in notable response rates (complete cytogenetic response: 43% vs 47%) and durable progression-free survival (70% vs 80%). High response rates were achieved with different mutations except T315I, including highly imatinib-resistant mutations in the P-loop region. Impaired responses were observed with some mutations with a dasatinib median inhibitory concentration (IC50) greater than 3nM; among patients with mutations with lower or unknown IC50, efficacy was comparable with those with no mutation. Overall, dasatinib has durable efficacy in patients with or without BCR-ABL mutations. All trials were registered at http://www.clinicaltrials.gov as NCT00123474, NCT00101660, and NCT00103844.

Beschreibung: Abstract 2212 Poster Board II-189 Treatment of Chronic Myeloid Leukemia (CML) has shown an outstanding progress while new understanding of the disease has increased significantly. Nevertheless in the era of targeted therapy, Sokal index remains a dominant prognostic determinant of newly diagnosed CML patients. Our study has aimed to identify novel prognostic indicators to improve both an initial assessment and subsequent monitoring of CML patients. Initially, we have found that the protein-tyrosine phosphatase SHP1, that has a tumour suppressor activity, may play an important role in the resistance to imatinib treatment. We applied gene profiling and proteomic bidimensional electrophoresis to compare the differential pattern of gene and protein expression between KCL22s (imatinib-sensitive) and KCL22r (imatinib-resistant) cell lines. We found SHP1 to be one of the most differentially expressed genes. By ESI-TRAP MS technique, we found that one of the main interactors of SHP1 is SHP2, a protein phosphatase well known as positive regulator of oncogenic pathways, including the Ras/MAPK pathway. Gain-of-function mutations in SHP2 gene, have been described in various haematopoietic neoplasias and myeloproliferative disorders including Juvenile Chronic Myelomonocytic Leukemia. This protein is regulated throw phosphorylation on 542- and 580-Tyr, and unlike SHP1, acts as a positive regulator of the same oncogenic pathways. We found that KCL22r cell line, that has low SHP1 levels, showed complete phosphorylation of both SHP2 tyrosine residues, while these residues are not phosphorylated in the KCL22s line, which could explain an important mechanism for imatinib sensitivity. Consistently with this hypothesis, knock-down of SHP2 phosphatase in KCL22r by a specific shRNA resulted in 60% inhibition of KCL22r proliferation. Furthermore, the KCL22rSHP2- cells showed significant reduction in STAT3 (60%) and ERK1/2 (70%) phosphorylation. Our initial results from CML patients (Esposito et al , ASH 2008 Abs 1106) have suggested a differential expression of SHP1 in patients with different response to imatinib treatment. To further explore the role of SHP1 as a determinant of imatinib sensitivity we evaluated the expression of SHP1 in 93 newly-diagnosed CML patients enrolled into the TOPS trial investigating 400mg versus 800mg imatinib (Cortes et al, EHA 2008). The results of this study indicate that the mRNA levels of SHP1, as assessed by QPCR in peripheral blood of patients at the time of enrolment, are significantly different between patients who do or don't achieve Major Molecular Response (MMR) by 12 months (7.9±4.0 vs. 5.9±3.4; p=0.01). Logistic regression was used to estimate regression coefficients and corresponding odds ratio using MMR by 12 months as outcome variable in our model. Since the 25th and 75th percentiles of SHP1 were 4.3 and 8.4, respectively (resulting in an interquartile range of 4.1), statistical analysis shown that a value of 4.1 or more in SHP1 is associated with almost 2-fold odds of achieving MMR by 12 months (OR=1.92; 95% CI=1.12, 3.29; p=0.018). Moreover, in a contingency table, chi-square analysis has been shown a high risk of not achieving MMR by 12 month in those patients with either low SHP1 expression and high Sokal score, when compared with patients with high-intermediate SHP1 expression and low-intermediate Sokal score (p=0.0068). In conclusion, these results suggest that, measuring expression levels of SHP1 could be of value in assessing newly diagnosed CP-CML patients and estimating treatment response, which could help optimizing Gleevec treatment, or recommending patients to more potent TKIs. Supported by Novartis Oncology, Clinical Development, TOPS Clinical Correlative Studies Network Disclosures: Saglio: Novartis: Honoraria; Celgene: Honoraria. Pane:Novartis: Research Funding; Ministero dell'Università/PRIN: Research Funding; Regione Campania: Research Funding; Ministero della Salute/Progetto integrato Oncologia: Research Funding.

Beschreibung: Abstract 2189 Poster Board II-166 Introduction. The organic cation transporter 1 (OCT-1) is the major active influx transporter for imatinib in PB mononuclear cells (MNC) from CML patients. We have previously demonstrated that the functional activity of the OCT-1 protein (OCT-1 Activity, OA) in MNC from chronic phase (CP) CML patients is highly variable (mean: 7.2 ng/200,000 cells, standard deviation: 6.4). We also demonstrated that the MNC OA is significantly related to a patient's sensitivity to imatinib-induced kinase inhibition, and their subsequent molecular response. In addition, we have recently demonstrated that OA is predictive of event free and transformation free survival to 5 years (White ASH submitted 2009). This is of a greater importance for those patients on lower doses of imatinib (below 600mg). For these patients who have a low MNC OA, 82% failed to achieve a major molecular response (MMR) by 18 months of imatinib treatment, as opposed to 17% for patients with a high MNC OA (p=0.022). Recently, we have shown that the OA in CML CD34+ cells is significantly lower than that found in mature CML cells (mean CD34+: 3.9, CD34-: 11.6 ng/200,000 cells, p

Beschreibung: Abstract 3282 Poster Board III-1 The kinase inhibitor dasatinib has demonstrated efficacy in patients with CML-CP who fail imatinib due to resistance or intolerance. Imatinib failure is often associated with the acquisition of resistant mutations within BCR-ABL. Failure of dasatinib is associated with a limited spectrum of mutations, which are T315I/A, V299L, and F317L/I/V, suggesting these mutations are dasatinib resistant (DR). Only a fraction of patients with T315I respond to dasatinib, most patients with F317L have hematologic responses but few have cytogenetic responses, and V299L is uncommon in imatinib-resistant patients but is mostly seen after dasatinib failure. In vitro data suggests Q252H and E255K/V also confer a degree of dasatinib resistance. However, their clinical association with dasatinib resistance or inferior response is unclear. This retrospective analysis seeks to determine if the mutation status at the start of dasatinib impacts the initial molecular response, and to examine the type of mutations lost and gained during therapy. To assess the significance of intermediate sensitivity (DI) mutations (Q252H and E255K/V), BCR-ABL levels were measured against the International Scale (IS), and mutation status was assayed at initiation of dasatinib (baseline), at progression, or study termination or completion (progression/completion). Data were taken from 479 patients with CML-CP treated with dasatinib 70 mg twice daily, after imatinib failure for the phase II START-C or -R studies. Patients were grouped according to their baseline mutation status: DR, DI, dasatinib sensitive (DS, all other mutations not DR or DI), and no mutations. Patients with more than one mutation at baseline that qualified for more than one grouping were rare, and classified according to the most resistant mutation. By 6 months of dasatinib therapy, patients with DR mutations at baseline had the highest levels of BCR-ABL transcripts (Table 1). By comparison, those with DI, DS, or no mutations had a reduced proportion with high transcript levels. In addition, no patients with DR at baseline achieved a reduction of BCR-ABL by 6 months to IS ratio 〈 1, whereas significant reductions were identified in patients with DI, DS, or no mutations. A subset of 267 patients had mutation analysis performed at progression/completion. Of these, 115 had mutations at baseline and 152 had no mutations. The patients with baseline imatinib resistance were more likely than those with imatinib intolerance to acquire new mutations. Of the resistant patients with no mutations at baseline, 7% (9/124) developed new mutations and the majority (7/9) was DR. Among resistant patients with baseline mutations, 23% (26/112) had new mutations and the majority was DR (20/26). Although 36 patients gained new mutations (including 16 T315I/A, 8 F317L, and 6 V299L), many baseline mutations were no longer detectable at progression/completion. DS mutations were lost in 68/102 patients. In total, 76 patients had detectable mutations at progression/completion, with 51% (39/76) having DR mutations but only 5% (4/76) with DI mutations. Patients with baseline DR mutations were more likely to retain their DR mutations (11/13). Of 8 patients with DI mutations at baseline, only 3 retained their DI mutations and 3 gained DR mutations. Of 94 patients with only DS mutations at baseline, 36 (38%) retained their DS mutations, and 17 (18%) developed DR mutations. Patients with high levels of BCR-ABL at 3 months had the highest incidence of new DR mutations at progression/completion (18/145 evaluable patients; 12%) compared to patients with lower levels (5/79; 6%). In conclusion, the development of new mutations during second-line dasatinib is rare (36/267). Patients who harbored DI mutations at baseline were also rare, and an expanded prospective analysis of dasatinib efficacy in this cohort may be necessary to clarify their significance. However, from the current analysis there is no compelling clinical evidence to suggest that these patients have an inferior molecular response. Relative to DR mutations, the DI mutations (Q252H and E255K/V) were rarely present at progression/completion. Patients with baseline mutations and 6-month BCR-ABL transcript level after second-line dasatinib IS ratio ≤ 1.0 1 〈 IS ratio ’ 10 IS ratio 〉 10 DR 0% (0/13) 23% (3/13) 77% (10/13) DI 56% (5/9) 0% (0/9) 44% (4/9) DS 36% (46/128) 20% (25/128) 45% (57/128) No mutations 42% (92/221) 18% (40/221) 40% (89/221) Disclosures: Branford: Bristol-Myers Squibb: Honoraria, Research Funding; Novartis: Honoraria, Research Funding. Hochhaus:Bristol-Myers Squibb: Research Funding; Novartis: Research Funding. Bahceci:Bristol-Myers Squibb: Employment. Ploughman:Bristol-Myers Squibb: Employment. Mukhopadhyay:Bristol-Myers Squibb: Employment. Hughes:Bristol-Myers Squibb: Advisor, Honoraria, Research Funding; Novartis: Advisor, Honoraria, Research Funding.

Beschreibung: Abstract 1127 Poster Board I-149 Background In the TOPS study, IM trough levels (Cmin) were collected from different race groups, mainly Caucasian and Asian, but also Black and others. Inter-ethnic differences in the PK of a drug are known to be important factors accounting for inter-individual variation in drug responsiveness. This analysis reports the comparison between Caucasian and Asian CML patients (pts) treated at doses of 400 mg QD and 400 mg bid (800 mg daily) of IM Cmin on Day 29 of initial treatment, clinical response, safety and tolerability. Methods Steady state IM Cmin on Day 29 and clinical response and safety data obtained during the first 12 months (mos) of treatment were obtained from pts randomized 2:1 to 800 mg or 400 mg daily IM. The steady-state Cmin was defined as predose concentration collected approximately within ±3 hours of the scheduled dosing time on Day 29. The associations of race with the rates of major molecular response (MMR) and complete cytogenetic response (CCyR) were evaluated. Correlation of IM exposure with clinical response (MMR and CCyR) was assessed by grouping pts into quartiles based on their measured IM Cmin levels at Day 29. The safety endpoint for each pt was the presence or absence of an adverse event (AE) of grade 3 or higher in the first 12 mos from the first dose. Results IM Cmin levels were available from 229 pts in TOPS including 54 Caucasians, 18 Asians, and 14 Black and others at 400 mg (total 86) and 103 Caucasians, 29 Asians, and 11 Black and others at 800 mg (total 143). For the first 12 mos, the means of the average dose intensities for Asian (mean [range], 362 [267-400] in 400 mg and 666 [226-800] in 800 mg) were not significantly different from Caucasian (386 [204-597] in 400 mg and 666 [289-800] in 800 mg) (P=0.070 and P=0.995 for the 400 mg and 800 mg arms, respectively). Mean (± SD) of IM Cmin levels (ng/mL) with respect to race are shown in Table 1. IM Cmin was slightly over-proportional to dose and showed large interpatient variability (CV=42-60%) for both dose groups regardless of the race group. In the lower quartile Cmin group (Cmin

Beschreibung: Abstract 3292 Poster Board III-1 Background: Nilotinib is a potent and highly selective BCR-ABL kinase inhibitor, approved for the treatment of Philadelphia positive CML patients (pts) in CP or accelerated phase (CML-AP) who are resistant or intolerant to prior therapy including imatinib. A recent analysis demonstrated an association between BCR-ABL transcript levels at 3 months (mos) and response in pts treated with second-line tyrosine kinase inhibitors (Branford et al. Blood. 2008). This multi-center analysis was conducted to examine the association specifically between the initial molecular response to nilotinib with response and outcomes. Methods: CML-CP pts (N = 321) with imatinib resistance or intolerance were included and post-baseline BCR-ABL transcript levels were available for 294 patients. Intolerant pts also exhibited some degree of resistance to imatinib and were not eligible for the study if demonstrating major cytogenetic response (MCyR), the primary study endpoint. We aimed to determine if the initial molecular response to nilotinib could predict the response and outcome of patients with or without BCR-ABL mutations at baseline or those with imatinib resistance or intolerance. BCR-ABL transcript levels at 3 mos were used to perform a landmark analysis to assess the association between the initial molecular response and estimated probability of MCyR, major molecular response (MMR), and event-free survival (EFS) at 24 mos. Events were defined as loss of hematologic or cytogenetic response, progression to AP/BC, discontinuation due to progression or death. The analysis excludes patients who had already attained MCyR (n = 111) or MMR [BCR-ABL% (IS) ≤ 0.1%] (n = 28) or who had an event (n = 22) within the first 3 mos of therapy for each respective landmark analysis. Patients censored within the first 3 mos were also excluded. Patients were then grouped according to their level of BCR-ABL% (IS). Results: BCR-ABL% (IS) at 3 mos correlated with MCyR rates at 24 mos; pts with BCR-ABL% (IS) ≤ 10 had better probability of response compared with pts with BCR-ABL% (IS) 〉 10 (62% vs 35%, respectively). This difference in MCyR rate was most significant for pts with baseline mutations (60% vs 19%, P = .006) and those with imatinib resistance (63% vs 33%, P = 0.0007). A similar trend was observed for patients without baseline mutations (64% vs 47%) and imatinib intolerance (57% vs 40%). BCR-ABL% (IS) at 3 mos was highly predictive of MMR rates at 24 mos (Table). Pts with BCR-ABL% (IS) values 〉 0.1 - ≤ 1 had significantly higher probability (65%) of achieving MMR for all patient groups, whereas those with BCR-ABL% (IS) 〉 10 had estimated rates of 10% or less. The BCR-ABL% (IS) value at 3 mos was also found to correlate with EFS at 24 mos (Table). The estimated EFS rate at 24 mos was highest for pts with BCR-ABL% (IS) values of ≤ 1 at 3 mos for each patient group and ranged from 75% to 100%. Patients with BCR-ABL% (IS) values 〉 10 at 3 mos had the poorest outcome and the estimated EFS rates ranged from 36% for patients with baseline mutations to 57% for those without baseline mutations. Conclusion: BCR-ABL% (IS) at 3 mos predicts response and long-term outcomes of imatinib-resistant and intolerant pts regardless of baseline mutation status at 24 mos on nilotinib therapy. Rapid reduction of BCR-ABL may be important for optimal response and outcome. Pts whose BCR-ABL % (IS) levels decreased below 10% at 3 mos demonstrated a high probability of achieving MMR and MCyR at 24 mos. Pts who achieve early molecular response may also have an increased probability of improved long-term outcomes on nilotinib therapy, while pts with BCR-ABL% (IS) value 〉 10 at 3 mos may have poorer prognosis. Disclosures: Branford: Novartis Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol-Myers Squibb: Honoraria, Research Funding. Kim:Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Wyeth: Research Funding. Haque:Novartis: Employment. Shou:Novartis: Employment. Woodman:Novartis: Employment. Kantarjian:Novartis: Research Funding. Radich:Novartis: Consultancy, Honoraria, Research Funding. Saglio:Novartis: Consultancy, Speakers Bureau; BMS: Consultancy, Speakers Bureau. Hughes:Bristol-Myers Squibb: Advisor, Honoraria, Research Funding; Novartis: Advisor, Honoraria, Research Funding. Hochhaus:Novartis: Research Funding.

Beschreibung: Abstract 3250 Poster Board III-1 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. Fig 1 In CML-CD34+ cells, Jak kinase inhibition abrogates the rescuing effect of cytokines on cell death induced by BCR-ABL blockade: In the absence of cytokines (No GF, n=11) short-term culture with 100 nM dasatinib (D100ST) reduced CFCs by 67% of control, however in the presence of 6-GFs (n=10), GM-CSF (n=10) or G-CSF (n=4) it could reduce CFCs by only 24%, 32% or 5% of control respectively (B) In the presence of GM-CSF (n= 4) or G-CSF (n= 4), combination of Jak inhibition and D100ST reduced CFC compared to dasatinib alone. Fig 1. In CML-CD34+ cells, Jak kinase inhibition abrogates the rescuing effect of cytokines on cell death induced by BCR-ABL blockade: In the absence of cytokines (No GF, n=11) short-term culture with 100 nM dasatinib (D100ST) reduced CFCs by 67% of control, however in the presence of 6-GFs (n=10), GM-CSF (n=10) or G-CSF (n=4) it could reduce CFCs by only 24%, 32% or 5% of control respectively (B) In the presence of GM-CSF (n= 4) or G-CSF (n= 4), combination of Jak inhibition and D100ST reduced CFC compared to dasatinib alone. 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.

Beschreibung: Abstract 1130 Poster Board I-152 Background Nilotinib is a selective and potent BCR-ABL inhibitor, with in vitro activity against most BCR-ABL mutants (excluding T315I) indicated for the treatment of patients with Philadelphia chromosome positive (Ph+) CML in CPor AP resistant or -intolerant to prior therapy, including imatinib. In a previous analysis of nilotinib in patients with BCR-ABL mutations, mutations occurring at three specific amino acid residues (E255K/V, Y253H, and F359C/V) were shown to be associated with less favorable response to nilotinib. The current analysis is based on mature data with a minimum follow-up of 24-months for all patients. Outcomes of patients at 24 months were analyzed by mutation type. Methods Imatinib-resistant CML-CP (n = 200) and CML-AP (n = 93) patients were subdivided into the following mutational subsets: no mutation, sensitive mutations (including mutations with unknown in vitro IC50). or E255K/V, Y253H, or F359C/V mutations at baseline. Patients with mutations of unknown in vitro sensitivity were classified as sensitive in this analysis based on a previous finding that patients with these mutations responded similarly to nilotinib as patients with sensitive mutation. Patients with baseline T315I mutations were excluded from this analysis. Patient groups were analyzed for kinetics and durability of cytogenetic and molecular response to nilotinib, as well as event-free survival (EFS), defined as loss of hematologic or cytogenetic response, progression to AP/BC, discontinuation due to disease progression, or death, and overall survival (OS). Results In CML-CP and -AP patients with no mutation, sensitive mutations, or E255K/V, Y253H, or F359C/V mutations, hematologic, cytogenetic and molecular responses are provided in the Table. Overall, patients with no mutations responded similarly to patients with sensitive mutations, whereas patients with E255K/V, Y253H, or F359C/V mutations had less favorable responses. This correlation was observed in both CML-CP and CML-AP patients, respectively. Median time to CCyR was 3.3 months (range, 1.0–26.7) for CML-CP patients with no mutations, and 5.6 months (range, 0.9–22.1) for patients with sensitive mutations. At 24 months, CCyR was maintained in 74% of CML-CP patients with no mutation and in 84% of patients with sensitive mutations. One patient with CML-CP and an E255K mutation achieved CCyR at 25 months and maintained until last assessment at 30 months. Median time to MMR was similar at 5.6 months (range, 0.9–25.8) for CML-CP patients with no mutations and 5.6 months (range, 2.7–22.1) for patients with sensitive mutations. No patient with a less sensitive mutation achieved MMR. Median EFS and 24-month estimated OS rate are provided in the Table. Conclusions Imatinib-resistant CML-CP and CML-AP patients treated with nilotinib therapy with BCR-ABL mutations (excluding E255K/V, Y253H, or F359C/V) achieved rapid and durable cytogenetic responses, and estimated EFS and OS at 24 months similar to that of patients with no mutations, respectively. Patients with E255K/V, Y253H, or F359C/V mutations had lower and less-durable responses and shorter EFS than patients with sensitive mutations. Alternative therapies may be considered for patients with these uncommon mutations (E255K/V, Y253H, and F359C/V). Disclosures Radich: Novartis: Consultancy, Honoraria, Research Funding. Hochhaus:Novartis: Research Funding. Branford:Novartis Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol-Myers Squibb: Honoraria, Research Funding. Shou:Novartis: Employment. Haque:Novartis: Employment. Woodman:Novartis: Employment. Kantarjian:Novartis: Research Funding. Hughes:Bristol-Myers Squibb: Advisor, Honoraria, Research Funding; Novartis: Advisor, Honoraria, Research Funding. Kim:Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Wyeth: Research Funding. Saglio:Novartis: Consultancy, Speakers Bureau; BMS: Consultancy, Speakers Bureau.

Beschreibung: Abstract 1129 Poster Board I-151 Background Nilotinib is a selective and potent BCR-ABL inhibitor, developed through structure-based drug design, indicated for the treatment of Philadelphia chromosome positive (Ph+) CML patients in CP or accelerated phase (AP) resistant or intolerant to prior therapy including imatinib. Recently, 24-month follow-up data from the pivotal nilotinib 2101 study demonstrated achievement of rapid and durable cytogenetic responses in the majority of patients and an excellent overall survival (OS) rate of 87%. The current update focuses on the major molecular response (BCR-ABL transcript levels ≤ 0.1% according to the international scale; MMR) of patients treated with nilotinib. Methods Imatinib-resistant and -intolerant CML-CP patients (n=321) were treated with nilotinib 400 mg twice daily and followed for at least 24 months. In this report, the efficacy parameters studied were: rate of MMR, rate of major and complete cytogenetic response (MCyR, CCyR), time to and duration of response, time to progression (TTP), and OS. Efficacy parameters were also analyzed based on the presence or absence of a CHR at study entry. Results The median duration of exposure to nilotinib was 18.7 months (〈 1.0–36.5), with 62% of patients on therapy for at least 12 months and 42% on therapy for ≥ 24 months. Median dose intensity of nilotinib was 788.5 mg/day, very close to planned dosing. Overall, 58% of patients required dose interruption (defined conservatively ≥ 1 day of interruption regardless of reason) with a median cumulative duration of interruption of 20 days (4% of days of exposure). Importantly, 73% of patients that required treatment interruptions resumed treatment after interruption at the planned dose. The achievement of MMR in imatinib-resistant and -intolerant CML-CP patients who had BCR-ABL transcript levels available post-baseline (n=294) were included in this efficacy analysis (Table). Of these patients, 105/294 (36%) entered the study with a CHR and 189/294 (64%) did not have a CHR at study entry. The overall MMR rate was 28%; MMR was higher in patients with CHR at study entry (38% vs. 22%). Overall, CCyR was achieved in 46% of patients, among whom 56% achieved MMR. Median time to MMR was 5.6 months. Overall, 77% and 84% of responding patients maintained MCyR and CCyR at 24 months, respectively. Overall (n=321), the estimated rate of progression-free survival (PFS), defined as progression to AP/BC or discontinuation due to progression or death, at 24 months was 64%, however, only 9 patients (3%) progressed to AP/BC based on actual laboratory values. PFS rate at 24 months was higher for patients with baseline CHR (77%) compared with patients without CHR at study entry (56%). OS at 24 months is 87% for the entire patient population. The safety profile of nilotinib remains unchanged at 24 months of follow-up. The majority of first episodes of grade 3/4 bilirubin and lipase elevations occurred within the first month of therapy and were brief in duration (median duration 15 days). The incidences of hepatic and pancreatic disorders on nilotinib were 1.3 and 1.7 per 100-patient years of therapy and no cumulative risk of hepatic and pancreatic events was observed in this population with longer follow-up. Importantly, discontinuations due to hepatobiliary adverse events were uncommon (n=2; 〈 1.0%). Conclusions Nilotinib therapy led to the achievement of MMR in a majority of patients with CCyR, and in 38% of patients with CHR at study entry. Furthermore, the response and outcomes of patients treated with nilotinib was higher in patients with CHR at baseline suggesting that patients with imatinib resistance and intolerance who lost cytogenetic response but not hematologic response have a more favorable response compared to those patients who have lost hematologic response when switched to nilotinib. Overall, the safety profile of nilotinib remains well-tolerated with long-term follow-up. At 24 months, nilotinib therapy remains an effective and tolerable therapy for patients with imatinib-resistant or -intolerant CML. Disclosures Kantarjian: Novartis: Research Funding. Giles:Novartis: Consultancy, Research Funding; BMS: Research Funding; Merck: Research Funding; Clavis: Research Funding. Bhalla:Novartis: Honoraria, Research Funding; Merck: Honoraria. Pinilla-Ibarz:Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Larson:Novartis: Consultancy, Honoraria, Research Funding. Gattermann:Novartis, Celgene: Honoraria, Participation in Advisory Boards on deferasirox clinical trials, Research Funding. Ottmann:Novartis: Consultancy, Honoraria, Research Funding, Speakers Bureau; Bristol-Myers Squibb: Consultancy, Honoraria, Research Funding. Hochhaus:Novartis: Research Funding. Radich:Novartis: Consultancy, Honoraria, Research Funding. Saglio:Novartis: Consultancy, Speakers Bureau; BMS: Consultancy, Speakers Bureau. Hughes:Bristol-Myers Squibb: Advisor, Honoraria, Research Funding; Novartis: Advisor, Honoraria, Research Funding. Martinelli:Novartis: Research Funding. Kim:Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Wyeth: Research Funding. Shou:Novartis: Employment. Gallagher:Novartis: Employment, Equity Ownership. Wang:Novartis: Employment. Cortes-Franco:Novartis: Honoraria, Research Funding, Speakers Bureau; Wyeth: Honoraria, Research Funding, Speakers Bureau; BMS: Honoraria, Research Funding, Speakers Bureau. Baccarani:Novartis Pharma: Consultancy, Honoraria, Research Funding, Speakers Bureau; Bristol-Mayer Squibb: Consultancy, Honoraria, Research Funding, Speakers Bureau. le Coutre:Novartis: Honoraria, Research Funding; BMS: Honoraria.