Abstract: Depth of molecular remission on tyrosine kinase inhibitor (TKI) treatment is of rising importance for chronic myeloid leukemia (CML) patients (pts) with regard to possible treatment discontinuation and competing TKIs available to improve molecular response. At present, it is unknown which level of deep molecular response is necessary for optimal prognosis and for successfully stopping therapy. The aim of this work is both to evaluate the technical feasibility of molecular monitoring at the mentioned level and to search for factors allowing to predict MR5.0 in pts on imatinib (IM)-based treatment. Methods Real-time quantitative PCR on mRNA BCR-ABL transcripts in addition to total ABL transcripts as internal control has been performed on a LightCycler platform in 1,442 pts within the randomized CML-Study IV and adapted according to the International Scale (IS). In order to qualify for MR5.0 the BCR-ABLIS expression should meet one of the following criteria: a positive result ≤0.001% or a negative result with a minimum sample quality of 100,000 ABL copies (Cross et al., Leukemia 2012). Calculating cumulative incidences of remission or progression, the competing risks progression and/or death before possible progression were considered. Cox models were estimated for the multivariate analysis. Results In 1,198 of the 1,442 molecularly examined pts at least one sample fulfilled the sensitivity criteria for a MR5.0 (8,266 of 24,101 samples, 34.3%). Cumulative incidence of MR5.0 was 51% at 8 years. The median time to MR5.0 according to randomized treatment arms differed as follows: IM 800mg 79.7 months (mos), IM 400mg 95.0 mos, IM 400mg + IFNα 98.0 mos, IM 400mg + AraC 103.3 mos, IM 400mg after IFN failure 112.9 mos. A Cox model examining the different treatment arms compared to IM 400mg revealed a significantly higher chance for MR5.0 in the IM 800mg arm (HR 1.305, 95% CI 1.003-1.698, p=0.048). Baseline factors like thrombocytosis 〉 450/nl were associated with better responses (HR 1.701 compared to 〈 450/nl, 95% CI 1.405-2.059, p 〈 0.001) and higher leukocyte counts 〉 100/nl (HR 0.503 compared to 〈 50/nl, 95% CI 0.400-0.632, p 〈 0.001) and 50-100/nl (HR 0.746 compared to 〈 50/nl, 95% CI 0.591-0.942, p=0.014) with unfavorable responses. Other upfront factors like age, gender, blasts, eosinophils, hemoglobin, and EUTOS score did not significantly influence the probability for MR5.0. Taken all treatment arms together, our analyses have shown that the chance of achieving a MR5.0 by 8 years was considerably reduced if the pts had a BCR-ABLIS 〉 10% at 3 mos (40.2% vs 58.0%), 〉 1% at 6 mos (40.3% vs 68.7%), 〉 0.1% at 12 mos (37.7% vs 72.0%), and 〉 0.1% at 24 mos (21.5% vs 60.5%). Conclusion This evaluation of a large randomized trial reveals feasibility of MR5.0 detection in the majority of pts underlining the benefits of standardized molecular monitoring on the IS with optimized highly sensitive technologies. Baseline low leukocyte count, high thrombocyte count and high dose IM treatment are predictors of future MR5.0. Further, early molecular landmarks qualify for excellent outcome giving hope to a rising number of pts to successfully discontinue treatment and avoid possible side effects or comorbidities. Disclosures: Müller: Novartis: Consultancy, Honoraria, Research Funding; BMS: Consultancy, Honoraria, Research Funding; Ariad: Consultancy, Honoraria, Research Funding. Hehlmann:BMS: Consultancy, Research Funding; Novartis: Research Funding. Hochhaus:Novartis: Consultancy, Honoraria, Research Funding, Travel Other; BMS: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy, Honoraria; Ariad: Consultancy, Honoraria. Saussele:Novartis: Honoraria, Research Funding, Travel Other; BMS: Honoraria, Research Funding, Travel, Travel Other; Pfizer: Honoraria.

Abstract: Current evidence indicates that acquired genetic instability in chronic myeloid leukemia (CML) as a consequence of the balanced reciprocal translocation t(9;22)(q34;q11) or the variant translocation t(v;22) and the resulting BCR-ABL fusion causes the continuous acquisition of additional chromosomal aberrations (ACA) and mutations and thereby progression to accelerated phase and blast crisis (BC). At least 10% of patients in chronic phase (CP) CML show ACA already at diagnosis and more than 80% of patients acquire ACA during the transformation process into BC. Therefore, alterations at diagnosis as well as acquisition of chromosomal changes during treatment are considered as a poor prognostic factor. Differences in progression-free survival (PFS) and overall survival (OS) have been detected depending on the type of ACA. Patients with major route ACA (+8, i(17)(q10), +19, +der(22)t(9;22)(q34;q11)) and with other alterations like -X, del(1)(q21), del(5)(q11q14), +10, -21 at diagnosis resulting in an unbalanced karyotype have a worse outcome. Patients with minor route ACA (for example reciprocal translocations other than the t(9;22)(q34;q11) (e.g. t(1;21), t(2;16), t(3;12), t(4;6), t(5;8), t(15;20)) resulting in a balanced karyotype show no differences in OS and PFS compared to patients with the standard translocation, a variant translocation or the loss of the Y chromosome (Fabarius et al., Blood 2011). Here we compare the type of chromosomal changes (i.e. balanced vs. unbalanced karyotypes) during the course of the disease from CP to BC aiming to provide a valid parameter for future risk stratification. Patients and Methods Clinical and cytogenetic data available from 1,346 out of 1,524 patients at diagnosis (40% females vs. 60% males; median age 53 years (range, 16-88)) with Philadelphia and BCR-ABL positive CP CML included until March 2012 in the German CML-Study IV (a randomized 5-arm trial to optimize imatinib therapy) were investigated. ACA were comparatively analyzed in CP and in BC. Results At diagnosis 1,174/1,346 patients (87%) had the standard t(9;22)(q34;q11) only and 75 patients (6%) had a variant t(v;22). Ninety-seven patients (7%) had additional cytogenetic aberrations. Of these, 44 patients (3%) lacked the Y chromosome (-Y) and 53 patients (4%) had ACA. Regarding the patients with ACA thirty-six of the 53 patients (68%) had an unbalanced karyotype and 17/53 patients (32%) a balanced karyotype. During the course of the disease 73 patients (out of 1,524 patients) developed a BC during the observation time (5%). Cytogenetic data were available in 52 patients with BC (21 patients with BC had no cytogenetic analysis). Three patients had a normal male or female karyotype after stem cell transplantation. Nine patients showed the translocation t(9;22)(q34;q11) or a variant translocation t(v;22) (six and three patients, respectively) only and in 40 patients ACA could be observed in BC (40/49 (82%)). Out of these 40 patients with ACA, 90% showed an unbalanced karyotype whereas only 10% of patients had a balanced karyotype. No male patient in BC showed the loss of the Y chromosome pointing to a minor effect of this numerical alteration on disease progression. Conclusion We conclude that patients with CML and unbalanced karyotype at diagnosis are under higher risk to develop CML BC compared to patients with balanced karyotypes or compared to patients without ACA. In BC, 90% of CML patients showed unbalanced karyotypes (only 68% of CML patients at diagnosis have unbalanced karyotypes) supporting the hypothesis that the imbalance of chromosomal material is a hallmark of disease progression, representing the natural history of the disease from CP to BC and indicating therefore a strong prognostic impact. Consequently, different therapeutic options (such as intensive therapy or stem cell transplantation) should be considered for patients with unbalanced karyotypes in CP CML at diagnosis. Disclosures: Haferlach: MLL Munich Leukemia Laboratory: Employment, Equity Ownership. Hehlmann:BMS: Consultancy, Research Funding; Novartis: Research Funding. Hochhaus:Novartis: Consultancy, Honoraria, Research Funding, travel Other; BMS: Consultancy, Honoraria, Research Funding; Pfizer : Consultancy, Honoraria; Ariad : Consultancy, Honoraria. Müller:Ariad: Honoraria; BMS: Honoraria, Research Funding; Novartis: Honoraria, Research Funding, Speakers Bureau. Saussele:Pfizer: Honoraria; BMS: Honoraria, Research Funding, Travel, Travel Other; Novartis: Honoraria, Research Funding, Travel Other.

Abstract: Introduction: The clonal selection of a mutant BCR-ABL positive clone can be observed in about one of two patients with imatinib-resistant chronic myeloid leukemia (CML). The early detection of BCR-ABL kinase domain mutations is crucial, since it allows to change the tyrosine kinase inhibitor (TKI) regimen in a timely manner and may therefore prevent disease progression and the accumulation of further genetic lesions. European LeukemiaNet (ELN) recommendations suggest a mutation analysis if optimal response criteria are not achieved at 3, 6, 12 or 18 months, or whenever a loss of optimal response occurs (Soverini et al., Blood 2011). Several attempts have been made to derive this indication from a specific increase of BCR-ABL levels. Here we report on the correlation of a rise in BCR-ABL transcript levels and the prevalence of BCR-ABL kinase domain mutations in imatinib-treated patients of the CML-Study IV. Methods: A total of 1,173 patients were enrolled until 2009 and randomized to one of four imatinib-based treatment arms. BCR-ABLIS of 988 patients was determined in 7,876 samples by quantitative RT-PCR in the central laboratory (median sample number per patient: 8.4, range 1-37; median follow up: 34 months, range 0-86), representing the eligible patients for the study. Thereby, the estimated intra-laboratory variance is assumed to be about 20%. A first rise of BCR-ABLIS to at least two-fold and 〉 0.1% between two samples of a patient's molecular course defined a sample suspected of bearing a mutant BCR-ABL positive clone. A mutation analysis was performed on this critical sample by direct sequencing of ABL exons 4 to 10. Results: A critical rise in BCR-ABLIS was observed in 231 of 988 patients (23%) after a median of 15.2 months on treatment (range 2.8-59.4). In the corresponding sample 33 mutant clones could be detected in 31 patients (13%). Thereby a steeper rise of BCR-ABLIS was correlated with a higher incidence of BCR-ABL mutations in the respective group (table). A total of 18 different mutations could be detected, the most frequent were: M244V, n=7 (21%); E255K, n=4 (12%); T315I, n=3 (9%); L248V, G250E, L387M and F486S, n=2 (6%), respectively. Mutations occur in a substantial proportion (8%) of patients with an only 2 to 3-fold rise of BCR-ABLIS transcript levels (table). Therefore, the most sensitive cut-off should be applied and mutation analysis may be triggered by a doubling of BCR-ABL transcripts at levels 〉 0.1% IS. Conclusion: BCR-ABL kinase domain mutations occur already in a substantial proportion of patients with a doubling of BCR-ABL transcript levels, which should determine mutation analysis. Table 1. Rise of BCR-ABL expression Patients (n) Patients with BCR-ABL mutations (n) Patients with BCR-ABL mutations (%) Inter-sample interval(median, days) 2 to 3-fold 72 6 8.3 98 3 to 5-fold 50 3 6.0 100 5 to 10-fold 39 4 10.3 99 10 to 100-fold 49 10 20.4 98 〉 100-fold 21 8 38.1 125 〉 2-fold (total) 231 31 13.4 101 Disclosures Hanfstein: Novartis: Research Funding; Bristol-Myers Squibb: Honoraria. Hehlmann:Novartis: Research Funding; Bristol-Myers Squibb: Research Funding. Saussele:Novartis: Honoraria, Research Funding, Travel Other; Bristol-Myers Squibb: Honoraria, Research Funding, Travel, Travel Other; Pfizer: Honoraria, Travel, Travel Other. Schnittger:MLL Munich Leukemia Laboratory: Equity Ownership. Neubauer:MedUpdate: Honoraria, Speakers Bureau. Kneba:Novartis: Consultancy, Equity Ownership, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Pfirrmann:Novartis: Consultancy; Bristol-Myers Squibb: Honoraria. Hochhaus:Pfizer: Consultancy, Research Funding; ARIAD: Honoraria, Research Funding; Bristol-Myers Squibb: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Research Funding. Müller:Novartis: Honoraria, Research Funding; Bristol Myers Squibb: Honoraria, Research Funding; ARIAD: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding.

Abstract: Abstract 3761 Introduction: Early assessment of molecular and cytogenetic response at 3 months of imatinib treatment has been shown to predict survival and might trigger treatment intensification in slow responders who are supposed to harbor a BCR-ABL positive clone with inferior susceptibility to tyrosine kinase inhibition (Hanfstein et al., Leukemia 2012). BCR-ABL transcript levels at 3 months depend on levels at diagnosis and the subsequent decline under treatment. Which of both parameters determines the clinical course and allows for prediction of survival is unclear. The BCR-ABL/ABL ratio is supposed to be skewed for high values, e.g. 〉 10%, due to the fact that ABL transcripts are also amplified from the fusion gene and in fact BCR-ABL/(ABL + BCR-ABL) is determined. Therefore, Beta-glucuronidase (GUS) was used as reference gene to determine high transcript levels at diagnosis. In addition, the linearity of the BCR-ABL/GUS scale allowed for an optimization of prognostic cut-off levels. We compared the significance of 1) BCR-ABL/GUS at diagnosis, 2) BCR-ABL/GUS at 3 months, 3) the individual reduction of transcripts given by (BCR-ABL/GUS at 3 months)/(BCR-ABL/GUS at diagnosis), and 4) the established 10% BCR-ABL/ABL landmark expressed on the international scale (BCR-ABLIS). Patients and methods: A total of 337 patients (pts) were investigated. According to the protocol of the German CML study IV pts could have been pre-treated with imatinib up to 6 weeks before randomization. 56 pts with imatinib onset before initial blood sampling within the study were excluded from the analysis. A total of 281 evaluable patients (median age 51 years, range 17–85, 42% female) were treated with an imatinib-based therapy consisting of imatinib 400 mg/d (n=76), imatinib 800 mg/d (n=110) and combinations of standard dose imatinib with interferon alpha (n=84) and low-dose cytarabine (n=11). Median follow-up was 4.8 years (range 1–10). Transcript levels of BCR-ABL, ABL, and GUS were determined by quantitative RT-PCR from samples taken before imatinib onset (“at diagnosis”) and 3 month samples. Only patients expressing typical BCR-ABL transcripts (b2a2 and/or b3a2) were considered. Disease progression was defined by the incidence of accelerated phase, blastic phase or death from any reason. A landmark analysis was performed for progression free survival (PFS) and overall survival (OS) after dichotomizing patients by a cut-off optimized by the cumulative martingale residuals method. Results: The median BCR-ABL/GUS ratio was 15.5% at diagnosis (0.07–271) and 0.62% at 3 months (0–34.7) reflecting a decline by 1.4 log. Disease progression was observed in 17 patients (6.0%), 14 of them died (5.0%). With regard to the above described parameters the following findings were observed: 1) at diagnosis no cut-off level could be identified for BCR-ABL/GUS ratios to separate two prognostic groups according to long-term PFS or OS. 2) At 3 months an optimized 2.8% BCR-ABL/GUS cut-off separated a high-risk group of 61 pts (22% of pts, 8-year PFS 78%, 8-year OS 81%) from a good-risk group of 220 pts (78% of pts, 8-year PFS 94%, 8-year OS 94%, p 〈 0.001, respectively). 3) At 3 months an individual reduction of BCR-ABL transcripts to at least 40% (0.4 log) of the initial level separated best and divided a high-risk group of 33 pts (12% of pts, 8-year PFS 74%, 8-year OS 80%) from a good-risk group of 248 pts (88% of pts, 8-year PFS 93%, 8-year OS 93%, p 〈 0.001, respectively). 4) When the established 10% BCR-ABLIS at 3 months was investigated, 63 pts were high-risk (22% of pts, 8-year PFS 82%, 8-year OS 85%) and 218 good-risk (78% of pts, 8-year PFS 91%, 8-year OS 93%, p=0.002 for PFS, p=0.011 for OS). Conclusions: Initial BCR-ABL transcript levels at diagnosis did not show prognostic significance. To predict survival at 3 months of treatment the absolute transcript level normalized by ABL or GUS can be used. Disclosures: Schnittger: MLL Munich Leukemia Laboratory: Equity Ownership. Hochhaus:Novartis, BMS, MSD, Ariad, Pfizer: Consultancy Other, Honoraria, Research Funding. Müller:Novartis, BMS: Consultancy, Honoraria, Research Funding.

Abstract: Background Five-year overall survival (OS) of chronic myeloid leukemia (CML) patients treated with imatinib exceeds 90%. With many tyrosine kinase inhibitors (TKI) available as treatment options for CML, the influence of TKI therapy on OS is difficult to define. Comorbidities can complicate randomized trials. Their influence on OS in CML has not been studied so far. Aims We sought to evaluate the influence of comorbidities at diagnosis of CML on remission rates and OS of patients with Philadelphia and/or BCR-ABL positive chronic-phase CML. The CML-Study IV, a randomized five-arm trial designed to optimize imatinib therapy alone or in combination, used very few exclusion criteria as compared to other studies which typically excluded patients with severe illnesses. Methods The age-adjusted Charlson Comorbidity Index (CCI) is the most extensively studied comorbidity index (Charlson ME et al., 1987) and has been validated for long-term studies. The score weighs a) the severity of comorbidities (e.g. one point is allocated to myocardial infarction and diabetes, two points to non-active malignancies) and b) the age of patients (with one point for each decade above 40 years). The CCI at diagnosis was calculated for each randomized patient. For the analyses, patients were grouped into CCI 2, 3-4, 5-6, and ≥7. Performance status was measured by the Karnofsky Score (KS) and patients were grouped into 50-80, 〉 80- 〈 100, and 100. Correlation analyses were performed by the chi-square test. Survival probabilities were calculated by Kaplan-Meier curves. Calculating cumulative incidences, the competing risks progression and/or death were considered. Cox models were estimated for the multivariate analysis to analyse the prognostic influence of the candidate factors age, sex, leukocytes, hemoglobin, EUTOS score, KS, and CCI on OS. Results 1551 patients were randomized from 2002 to 2012, 1524 patients were evaluable. Median follow-up time was 67.5 months. Additional to CML, 521 index comorbidities were reported in 1519 patients resulting in the following CCI groups: i) CCI 2: 589 patients, ii) CCI 3 or 4: 599 patients, iii) CCI 5 or 6: 229 patients, and iv) CCI ≥ 7: 102 patients. Median value of the CCI was 3 (range: 2-12). The distribution of the CCI groups was not different between treatment arms. Most common comorbidities were diabetes (n=106), non-active cancer (n=102), chronic pulmonary disease (n=74), renal insufficiency (n=47), myocardial infarction (n=38), cerebrovascular disease (n=29), congestive heart failure (n=28), and peripheral vascular disease (n=28). Between patients with CCI 2, 3-4, 5-6, and ≥7 no significant differences in remission rates were found neither for time to complete cytogenetic remission (CCR) nor for time to major molecular remission (MMR). Median times to CCR were 12.9, 12.6, 13.7, and 13.1 months and to MMR 17.5, 15.9, 16.5, and 18.1 months, respectively. No differences were observed between the CCI groups for the cumulative incidences of progression. As expected, significant differences in OS according to CCI at diagnosis were observed (s. Fig. 1, p 〈 0.001). Probabilities of OS at 8 years for patients with CCI 2, 3-4, 5-6, and ≥7 were 93.6%, 89.4%, 78.7%, and 45.2%. We found a correlation between CCI and KS (p 〈 0.001). In multivariate analysis CCI (p 〈 0.001), KS (p=0.022), and EUTOS Score (p=0.012) were significant predictors of OS. Hazard ratios for the CCI group 3-4, 5-6, 〉 7 (each vs. 2), were 1.695 (95%-confidence interval, CI 1.066-2.695), 3.231 (CI 1.942-5.376) and 6.495 (CI 3.817-11.111), respectively. Separating the CCI into an age-related part and a comorbidity-related part, the comorbidity-related part was still an important risk factor (Wald test, p=0.002). Conclusions Comorbidities of CML-patients do not seem to have an impact on the success of imatinib treatment. In CML-Study IV, even patients with a considerable comorbidity benefitted from imatinib as the chances to achieve MMR and CCR did not differ from those of healthier CML-patients. Our data also indicate that OS alone is not any more an appropriate measure for the effectiveness of a specific treatment for CML, as TKI have reduced the CML-related lethality to too low levels. Adjusting for comorbidity is essential for a valid comparison and interpretation of OS observed with different TKIs in CML-patients. Disclosures: Saussele: Pfizer: Honoraria; BMS: Honoraria, Research Funding, Travel, Travel Other; Novartis: Honoraria, Research Funding, Travel Other. Hehlmann:BMS: Consultancy, Research Funding; Novartis: Research Funding. Hochhaus:Novartis: Consultancy, Honoraria, Research Funding, Travel Other; BMS: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy, Honoraria; Ariad: Consultancy, Honoraria. Müller:Ariad: Honoraria; BMS: Honoraria, Research Funding; Novartis: Honoraria, Research Funding, Speakers Bureau.

Abstract: Early assessment of BCR-ABL transcript levels at 3 months allows the prediction of survival and may serve as a trigger for treatment intensification in CML patients with slow response to imatinib. The exact decline of BCR-ABL transcript levels within the first 3 months of treatment is defined by the ratio BCR-ABL transcripts at 3 months to BCR-ABL transcripts at baseline. This ratio might better reflect the individual biology of disease and its susceptibility to tyrosine kinase inhibition. Methods A total of 408 chronic phase CML patients (pts) with baseline and 3 month blood samples available in one single laboratory were investigated. Pts with pre-treatment before first blood sampling were excluded (imatinib with or without hydroxyurea, n=58; hydroxyurea only, n=49). A total of 301 evaluable pts (median age 52 years, range 18-85, 41% female) were treated with an imatinib-based therapy within the CML-Study IV. Median follow-up was 4.8 years. Transcript levels of BCR-ABL, total ABL, and beta-glucuronidase (GUS) were determined by quantitative RT-PCR. Exploratory landmark analyses were performed with regard to overall and progression-free survival (OS, PFS) to evaluate the prognostic significance of (i) BCR-ABL/GUS before treatment, (ii) the individual reduction of transcripts given by (BCR-ABL/GUS at 3 months) / (BCR-ABL/GUS before treatment), and (iii) the 3-month 10% BCR-ABLIS landmark. Results The median BCR-ABL/GUS ratio was 15.5% at diagnosis (0.06-107) and 0.63% at 3 months (0-84) reflecting a decline to the 0.04-fold (1.4 log reduction). i) No prognostic cut-off could be identified for BCR-ABL/GUS before treatment. ii) A reduction to the 0.35-fold of the initial BCR-ABL transcript level at diagnosis (0.46 log reduction) was identified as best cut-off according to a hazard ratio of 5.6 (95%-CI 2.3-13.4, p 〈 0.001 for PFS). Using this cut-off a high-risk group of 48 pts (16% of pts, 5-year PFS and OS: 77% and 83%) was separated from a good-risk group of 253 pts (84% of pts, 5-year PFS and OS: 96% and 98%). iii) As a comparison we investigated the 10% BCR-ABLIS landmark at 3 months with a hazard ratio of 2.4 (95%-CI 1.0-5.8, p=0.06 for PFS). With this landmark a high-risk group of 67 pts (22% of pts, 5-year PFS and OS: 87% and 90%) was separated from a good-risk group of 234 pts (78% of pts, 5-year PFS and OS: 95% and 97%). Conclusion A two-group risk stratification according to the individual reduction of BCR-ABL transcripts to the 0.35-fold of pre-treatment levels yields a superior separation of risk groups with a 5-year difference of 19% for PFS and 15% for OS. This predictive marker might identify patients at risk more precisely than 3-month 10% BCR-ABLIS. Disclosures: Hehlmann: BMS: Consultancy, Research Funding; Novartis: Research Funding. Saussele:Novartis: Honoraria, Research Funding, Travel Other; BMS: Honoraria, Research Funding, Travel, Travel Other; Pfizer: Honoraria. Hochhaus:Novartis: Consultancy, Honoraria, Research Funding, Travel Other; BMS: Consultancy, Honoraria, Research Funding; ARIAD: Consultancy, Honoraria; Pfizer: Consultancy. Müller:Novartis: Consultancy, Honoraria, Research Funding; BMS: Consultancy, Honoraria, Research Funding; Ariad: Consultancy, Honoraria, Research Funding.

Abstract: Tyrosine kinase inhibitors (TKI) have changed the natural course of CML. Their efficacy leads to normal life expectancy in the vast majority of patients. With the advent of 2nd generation TKI and the now available choice of drugs, safety issues have gained interest. We have used the randomized CML-Study IV for a long-term safety evaluation of imatinib. Study and Patients CML-Study IV comprises 1551 patients randomized to 5 treatment arms with 3 imatinib-based combinations and 2 different imatinib-dose schedules. 1501 patients have received imatinib and were evaluable. Median age at diagnosis was 53 years, 88% were EUTOS low risk. At the last evaluation (04/11/2013) 1003 patients still received imatinib, 164 had died, 275 were switched to a 2nd generation TKI, 106 were transplanted. The longest observation time was 11.5 years, the median observation time was 6.5 years, with a 10-year survival probability of 84 %. The median time to imatinib discontinuation has not been reached after 10.2 years. 80 patients are under observation for more than 10 years, 18 of these have discontinued imatinib. Out of the 1501 patients that had received imatinib, 1375 patients received imatinib as first-line treatment and had a sufficient documentation of treatment. Methods AE were reported at each follow-up visit. The CTC AE list of the NCI was used for coding of AE and severity grading. Additionally, for detection of hematologic AE lab results were screened for deviations from reference ranges. The AE were analyzed according to the “as treated” principle, using Kaplan-Meier curves (virtually no competing risks, almost all patients died after end of imatinib treatment). Only the first event of the respective type was considered. All analyses started at the first day of imatinib treatment and were censored when the patient discontinued imatinib, received another treatment or died. To assess the differences between men and women, Cox models were estimated. Results In 1137 out of 1375 patients (83%) non-hematologic AE (5160 singular events) were reported during imatinib treatment (all grades), in 322 grade 3/4 AE (23%) (645 singular events). At 3 years, probability of a non-hematologic AE (any grade) was already 76% (95%-CI: 73-79%), at 6 years 85% (95%-CI: 82-88%) and at 8 years 91% (Fig.1). The probability of grade 3/4 non-haematologic AE was 38% (95%-CI: 34-42%) at 6 years and 43% (CI: 37-48%) at 8 years. 156 patients reported hematologic grade 3/4 AE (187 singular events).The probability of hematologic grade 3/4 AE was 17% at 6 years (95%-CI: 15-21%) with most events observed during the first year of treatment (probability after one year 10.5%). The most frequently reported non-hematologic AE (all grades, any time) were gastrointestinal (6-year-probability 52%, 95%-CI: 48-56%), fluid overload or edema (6y-prob. 45%, 95%-CI: 40-49%), rash (6y-prob. 32%, 95%-CI: 28-36%), myalgia or arthralgia (6y-prob. 30%, 95%-CI: 27-34%), fatigue (6y-prob. 26%, 95%-CI: 22-29%), flu-like symptoms (6y-prob. 22%, 95%-CI: 19-26%), infections (6y-prob. 24%, 95%-CI: 20-28%) and neurological symptoms (6y-prob. 26%, 95%-CI: 22-29%). AE probability profiles over time have been generated for each AE (Figs. 2-3). For women the risk for non-hematologic events was increased 1.35-fold (95% CI: 1.18-1.55) for all grades (Figs. 1-3) and 1.13-fold (95% CI: 0.91-1.41) for grade 3/4, and 1.26-fold (95% CI: 0.91-1.71) for grade 3/4 hematologic AE. In 5 patients peripheral arterial occlusive disease grade 2 or 3 was reported, but none could be clearly assigned to imatinib (vascular risk profile of one patient incompletely reported). A definite association between any AE and death was not found. Conclusion As AE by definition may or may not be considered related to the medical treatment an exact assessment of the safety of imatinib is difficult. Most AE were recorded during the first three years with decreasing frequency later on. The increased AE risk in women was mostly grade 1/2 and is commonly seen also in other treatment areas. Given that no imatinib-related death was recorded and that grade 3/4 AE could typically be properly treated we consider imatinib as a safe, comparably well tolerated TKI even after prolonged treatment. After 10 years imatinib continues to be an excellent choice for the treatment of CML in most patients. Disclosures: Hehlmann: Novartis: Research Funding; BMS: Consultancy, Research Funding. Hochhaus:Novartis: Consultancy, Honoraria, Research Funding, Travel Other; BMS: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy, Honoraria; Ariad: Consultancy, Honoraria. Müller:Novartis: Honoraria, Research Funding, Speakers Bureau; BMS: Honoraria, Research Funding; Ariad: Honoraria. Saussele:Novartis: Honoraria, Research Funding, Travel Other; BMS: Honoraria, Research Funding, Travel, Travel Other; Pfizer: Honoraria.

Abstract: Abstract 913 Introduction: Acquired genetic instability in chronic myeloid leukemia (CML) as a consequence of the translocation t(9;22)(q34;q11) and the resulting BCR-ABL fusion causes the continuous acquisition of additional chromosomal aberrations and mutations and thereby progression to accelerated phase (AP) and blast crisis (BC). At least 10% of patients in chronic phase (CP) CML show additional alterations at diagnosis. This proportion rises during the course of the disease up to 80% in BC. Acquisition of chromosomal changes during treatment is considered as a poor prognostic indicator, whereas the impact of chromosomal aberrations at diagnosis depends on their type. Patients with major route additional chromosomal alterations (major ACA: +8, i(17)(q10), +19, +der(22)t(9;22)(q34;q11) have a worse outcome whereas patients with minor route ACA show no difference in overall survival (OS) and progression-free survival (PFS) compared to patients with the standard translocation, a variant translocation or the loss of the Y chromosome (Fabarius et al., Blood 2011). However, the impact of balanced vs. unbalanced (gains or losses of chromosomes or chromosomal material) karyotypes at diagnosis on prognosis of CML is not clear yet. Patients and methods: Clinical and cytogenetic data of 1346 evaluable out of 1544 patients with Philadelphia and BCR-ABL positive CP CML randomized until December 2011 to the German CML-Study IV, a randomized 5-arm trial to optimize imatinib therapy by combination, or dose escalation and stem cell transplantation were investigated. There were 540 females (40%) and 806 males (60%). Median age was 53 years (range, 16–88). The impact of additional cytogenetic aberrations in combination with an unbalanced or balanced karyotype at diagnosis on time to complete cytogenetic and major molecular remission (CCR, MMR), PFS and OS was investigated. Results: At diagnosis 1174/1346 patients (87%) had the standard t(9;22)(q34;q11) only and 75 patients (6%) had a variant t(v;22). In 64 of 75 patients with t(v;22), only one further chromosome was involved in the translocation; In 8 patients two, in 2 patients three, and in one patient four further chromosomes were involved. Ninety seven patients (7%) had additional cytogenetic aberrations. Of these, 44 patients (3%) lacked the Y chromosome (-Y) and 53 patients (4%) had major or minor ACA. Thirty six of the 53 patients (2.7%) had an unbalanced karyotype (including all patients with major route ACA and patients with other unbalanced alterations like -X, del(1)(q21), del(5)(q11q14), +10, t(15;17)(p10;p10), -21), and 17 (1.3%) a balanced karyotype with reciprocal translocations [e.g. t(1;21); t(2;16); t(3;12); t(4;6); t(5;8); t(15;20)]. After a median observation time of 5.6 years for patients with t(9;22), t(v;22), -Y, balanced and unbalanced karyotype with ACA median times to CCR were 1.05, 1.05, 1.03, 2.58 and 1.51 years, to MMR 1.31, 1.51, 1.65, 2.97 and 2.07 years. Time to CCR and MMR was longer in patients with balanced karyotypes (data statistically not significant). 5-year PFS was 89%, 78%, 87%, 94% and 69% and 5-year OS 91%, 87%, 89%, 100% and 73%, respectively. In CML patients with unbalanced karyotype PFS (p 〈 0.001) and OS (p 〈 0.001) were shorter than in patients with standard translocation (or balanced karyotype; p 〈 0.04 and p 〈 0.07, respectively). Conclusion: We conclude that the prognostic impact of additional cytogenetic alterations at diagnosis of CML is heterogeneous and consideration of their types may be important. Not only patients with major route ACA at diagnosis of CML but also patients with unbalanced karyotypes identify a group of patients with shorter PFS and OS as compared to all other patients. Therefore, different therapeutic options such as intensive therapy with the most potent tyrosine kinase inhibitors or stem cell transplantation are required. Disclosures: Haferlach: MLL Munich Leukemia Laboratory: Equity Ownership. Hochhaus:Novartis, BMS, MSD, Ariad, Pfizer: Consultancy Other, Honoraria, Research Funding. Müller:Novartis, BMS: Consultancy, Honoraria, Research Funding.

Abstract: Background: In the current ELN recommendations (Baccarani et al., Blood 2013) the optimal time point to achieve major molecular remission (MMR) is defined at 12 months after diagnosis of CML. MMR is not a failure criterion at any time point leading to uncertainties when to change therapy in CML patients not reaching MMR after 12 months. Aims: We sought to evaluate a failure time point for MMR using data of the CML-Study IV, a randomized five-arm trial designed to optimize imatinib therapy alone or in combination. In addition the optimal time-point to achieve a MMR should be evaluated. Methods: Patients with valid molecular analysis on MR4 level were divided randomly into a learning (LS) and a validation sample (VS). For the LS, MR2 (defined as BCR-ABL 〈 1% which corresponds to complete cytogenetic remission (Lauseker et al. 2014)), MMR and deep molecular remission levels (MR4 or deeper) monthly landmarks were defined between one and five years after diagnosis. A patient was considered to be in MR2, MMR or MR4 from the first diagnosis of the corresponding remission level and could only change to a higher level of response. Patients were censored after SCT. The best prediction time was found via dynamic prediction by landmarking (van Houwelingen, Scand J Stat 2007). For the failure time point analysis, for each of the resulting 48 landmarks, a Cox model was used to define the time to progression with age and EUTOS score as additional prognostic factors. Additionally, the regression coefficients of the model of one landmark were converted to hazard ratios (HR) and treated as dependent on the HRs of the other landmarks, using a cubic smoothing function (see Fig 1). The minimum of this function was considered to be the optimal landmark point for the prediction of progression-free survival (PFS). For the calculated time point, landmark analysis for probability of PFS (defined as appearance of accelerated phase, blast crisis or death) was performed in the VS. For the evaluation of the optimal time point of achieving a MMR the same analysis was done from 0.25 to 5 years to define the time to MR4 or deeper. Results: 1551 patients were randomized from 2002 to 2012, 1358 had a valid molecular analysis on the MR4 level. 114 patients in the imatinib after IFN arm and 16 patients with missing EUTOS score were excluded. Of the 1228 evaluable patients two thirds were randomly allocated to the LS (n=818) and one third to the VS (n=410). Percentage of patients of the LS in MR2, MMR and MR4 or deeper at one year was 28%, 29% and 14%, and at 5 years 5%, 21% and 71%, respectively. Monthly time points in between were also calculated. 44 patients of the LS reached MMR on second generation tyrosine kinase inhibitors.. The minimum of the cubic function of the HRs was found for MMR at 2.34 years with a HR of 0.25 (compared to patients without any remission) and 0.75 compared to those in MR2. For MR4 or deeper no exact time point could be calculated (see Fig. 1), although it was shown that the risk of progression was slightly lower for MR4 than for MMR. Since the time interval for molecular evaluation in the study is 3 months, the validation was done with 2.25 instead of 2.34 years. 364 of the 410 of the VS were still at risk at this time point and evaluable. A significant PFS advantage for patients in MMR could be demonstrated (p=0.018). At 8 years, the probability of PFS for patients in MMR was 90.8% (confidence interval 87.0-93.7%) vs. 80.5% (confidence interval 70.2-88.6%) for patients not in MMR (see Fig 2). For the optimal MMR analysis no singular time point could be calculated as the earlier a MMR was reached the higher was the chance to achieve a MR4. Conclusions: In this model, an optimal time point to predict PFS in patients with MMR was defined at 2.25 years after diagnosis and could be validated as significant. Nevertheless, patients being in MMR had a lower risk of progression than patients not being in MMR on any other time point as well. With this model we can give hints when to define MMR as failure and a change in therapy should be considered. Despite this we should keep in mind that the earlier MMR was achieved the higher was the chance to achieve deep molecular response later during therapy. Figure 1 Cubic smoothing function of the HR to predict PFS with confidence intervals Figure 1. Cubic smoothing function of the HR to predict PFS with confidence intervals Figure 2 Landmark analysis at 2.25 years for PFS of the VS Figure 2. Landmark analysis at 2.25 years for PFS of the VS Disclosures Saussele: Novartis: Honoraria, Research Funding, Travel Other; Bristol-Myers Squibb: Honoraria, Research Funding, Travel, Travel Other; Pfizer: Honoraria, Travel, Travel Other. Hehlmann:Bristol-Myers Squibb: Research Funding; Novartis: Research Funding. Schnittger:MLL Munich Leukemia Laboratory: Equity Ownership. Hanfstein:Novartis: Research Funding; Bristol-Myers Squibb: Honoraria. Neubauer:MedUpdate: Honoraria, Speakers Bureau. Kneba:Novartis: Consultancy, Equity Ownership, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Pfirrmann:Novartis: Consultancy; Bristol-Myers Squibb: Honoraria. Hochhaus:Novartis: Consultancy, Honoraria, Research Funding; Bristol-Myers Squibb: Consultancy, Honoraria; ARIAD: Honoraria, Research Funding; Pfizer: Consultancy, Research Funding. Müller:Novartis: Honoraria, Research Funding; Bristol Myers Squibb: Honoraria, Research Funding; ARIAD: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding.

Abstract: Abstract 67 Dose optimized imatinib (IM) at doses of 400– 800mg has been shown to induce faster and deeper cytogenetic and molecular – responses than standard IM (400mg/day). Since complete molecular remission (CMR 4.5) identifies a subgroup of patients who may stay in remission even after discontinuation of treatment, it was of interest to analyse whether CMR 4.5 is reached faster with dose optimized IM and whether CMR 4.5 correlates with survival. CMR 4 and CMR 4.5 are defined as ≤ 0.01% BCR-ABL IS or ≥ 4. log reduction and ≤ 0.0032% BCR-ABL IS or ≥ 4.5 log reduction, respectively, from IRIS baseline as determined by real-time PCR. CML-Study IV is a five arm randomized study of IM 400 mg vs IM 400 mg + IFN vs. IM 400 mg + Ara C vs. IM after IFN failure vs. IM 800 mg. In the IM 800 arm, a 6 weeks run in period at IM 400 mg was followed by a dose increase to 800 mg and then by a dose reduction according to tolerability. Grade 3 or 4 adverse effects (AE) were to be avoided. From July 2002 to March 2012 a total of 1551 patients with newly diagnosed chronic phase CML were randomized of whom 1525 were evaluable. Median age was 52 years, 88% were EUTOS low risk, 12% high risk, 36% were Euro score low risk, 52% intermediate and 12% high risk, 38% were Sokal low risk, 38% intermediate and 24% high risk. 113 patients were transplanted, 246 received 2nd generation TKI. 152 patients have died, 90 of CML or unknown reasons, 62 of not directly CML-related causes. After a median observation time of 67,5 months 6 years OS was 88.2% and PFS 85.6%. CCR, MMR, CMR 4 and CMR 4,5 were achieved significantly faster with dose optimized IM (400 – 800 mg). No significant differences in remission rates were observed between IM 400 mg and the combination arms IM 400 mg + IFN and IM 400 mg + Ara C, whereas IM after IFN failure thus far yielded significantly slower response rates. After 4 years CCR rates were for IM 400, IM 400 + IFN, IM 400 + Ara C, IM 400 after IFN, and IM 800, 80%, 75%, 73%, 59% and 80%, respectively, MMR rates 84%, 77%, 82%, 61% and 88%, CMR 4 rates 57%, 55%, 55%, 40% and 65%, and CMR 4.5 rates 40%,42%, 42%, 28% and 52%, respectively. CMR 4 was reached after a median of 27 months with IM 800 and 41.5 months with IM 400. CMR 4.5 was reached after a median of 41.5 months with IM 800 and 63 months with IM 400. EUTOS low risk patients reached all remissions faster than EUTOS high risk patients. The differences of CMR 4 rates between IM 800 and IM 400 at 3 years were 13% and at 4 years 8%, and of CMR 4.5 rates at 3 years 10% and at 4 years 13%. Grade 3 and 4 AE were not different between IM 400 and dose optimized IM 800. Independent of treatment approach, CMR 4 and more clearly CMR 4.5 at 3 years predicted better OS and PFS, if compared with patients without CMR 4 or CMR 4.5, respectively. CMR 4 and 4.5 were stable. After a median duration of CMR 4 of 3.7 years only 4 of 792 patients with CMR 4 have progressed. Life expectancy with CMR 4 and 4.5 was identical to that of the age matched population. We conclude that dose optimized IM induces CMR 4.5 faster than IM 400 and that CMR 4 and CMR 4.5 at 3 years are associated with a survival advantage. Dose optimized IM may provide an improved therapeutic basis for unmaintained treatment discontinuation in patients with CML. Disclosures: Hehlmann: Novartis: Research Funding. Müller:Novartis, BMS: Consultancy, Honoraria, Research Funding. Haferlach:MLL Munich Leukemia Laboratory: Equity Ownership. Schnittger:MLL Munich Leukemia Laboratory: Equity Ownership. Hochhaus:Novartis, BMS, MSD, Ariad, Pfizer: Consultancy Other, Honoraria, Research Funding.