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.

Abstract: Abstract 3746 Introduction: The increase of overall survival in chronic myeloid leukemia (CML) requires closer long-term observation in the face of a potential carcinogenicity of tyrosine kinase inhibitors (TKIs). Preclinical studies with imatinib in rats showed neoplastic changes in kidneys, urinary bladder, urethra, preputial and clitoral glands, small intestine, parathyroid glands, adrenal glands, and nonglandular stomach. Two epidemiologic studies on patients with chronic myeloproliferative neoplasms (CMPN) and CML (Frederiksen H et al., Blood 2011; Rebora P et al., Am J Epidemiol 2010) found an increased risk of secondary malignancies compared with the general population independent of treatment. In contrast, in a recent analysis of patients with CML and CMPN treated with TKI (Verma D et al., Blood 2011) a decreased risk of secondary malignancies was reported. Aims: To further elucidate the risk of TKI treated CML patients for the development of secondary malignancies we analysed data of the CML study IV, a randomized 5-arm trial (imatinib 400 mg vs. imatinib 800 mg vs. imatinib 400 mg in combination with interferon alpha vs. imatinib 400 mg in combination with AraC vs. imatinib 400 mg after interferon failure). Patients and methods: From February 2002 to April 2012, 1551 CML patients in chronic phase were randomized, 1525 were evaluable. Inclusion criteria allowed the history of primary cancer if the disease was in stable remission. Forty-nine malignancies were reported in 43 patients before the diagnosis of CML. If relapses occurred within 5 years after diagnosis of primary cancer they were not considered for further analysis. Median follow-up was 67.5 months. Age-standardized incidence rates were calculated from the age-specific rates using the European standard population (1976). Results: In total, 67 secondary malignancies in 64 patients were found in CML patients treated with TKI (n=61) and interferon alpha only (n=3). Twelve of these patients developed neoplasms after diagnosis of a primary cancer before diagnosis of CML, 5 patients with metastases or recurrence of the first malignancy (range of diagnosis 5–19 years after primary cancer). Median time to secondary malignancy was 2.5 years (range 0.1–8.3 years). The types of neoplasms were: prostate (n=9), colorectal (n=6), lung (n=6), non Hodgkin's lymphoma (NHL; n=7), malignant melanoma (n=5), skin tumors (basalioma n=4 and squamous cell carcinoma n=1), breast (n=5), pancreas (n=4), kidney (n=4), chronic lymphocytic leukemia (n=3), head and neck (n=2), biliary (n=2), sarcoma (n=2), and esophagus, stomach, liver, vulva, uterus, brain, cancer of unknown origin (each n=1). With these numbers the age-standardized incidence rates of secondary malignancies in CML patients were calculated: 534 cases per 100,000 for men (confidence interval [350;718]), and 582 for women (confidence interval [349;817] ). The incidence rates of the general population in Germany were 450 and 350 cases, respectively (“Krebs in Deutschland 2007/2008”, 8th ed., Robert Koch Institute, 2012). The incidence rate of NHLs was higher for CML patients than for the general population but this is not significant. Conclusions: In our cohort, the incidence rate of secondary neoplasms in CML patients was slightly increased compared to the general population. The most common secondary malignancies in CML patients under treatment were cancers of the skin, prostate, colon, lung and NHL. Since the occurrence of secondary neoplasia increases over time, long-term follow-up of CML patients is warranted. Disclosures: Müller: Novartis, BMS: Consultancy, Honoraria, Research Funding. Hochhaus:Novartis, BMS, MSD, Ariad, Pfizer: Consultancy Other, Honoraria, Research Funding. Hehlmann:Novartis: Research Funding.

Abstract: In acute leukemias, specific cytogenetic aberrations frequently correlate with myeloid or lymphoid phenotype of blasts and influence risk stratification. In chronic myeloid leukemia (CML) blast crisis (BC) it is not clear whether myeloid or lymphoid phenotype of blasts could be distinguished by specific chromosomal aberrations and have prognostic value. At diagnosis of CML, major route additional cytogenetic aberrations (ACA) like +8, i(17)(q10), +19, +der(22)t(9;22)(q34;q11) and minor route ACA like -X, del(1)(q21), del(5)(q11q14), +10,-21, resulting in an unbalanced karyotype have been described to adversely affect 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 did not show differences in overall survival and progression free survival compared to patients with the standard translocation, a variant translocation or the loss of the Y chromosome. Aim of this study was to analyze the impact of the phenotype (myeloid or lymphoid) on time to BC and on cytogenetic pattern. Methods 73 out of 1524 evaluable patients (4.8%) randomized until March 2012 to the German CML-Study IV (a 5-arm trial to optimize imatinib therapy) progressed to BC. Cytogenetic data of 23 out of 32 patients with myeloid BC and 14 out of 21 patients with lymphoid BC were available. In 15 patients, cytogenetic analysis were missing whereas 2 and 3 patients had megakaryoblastic and mixed phenotype, respectively and were not considered in this analysis. Karyotypes of lymphoid and myeloid BC were divided in major route and minor route ACA and balanced and unbalanced karyotypes. Categorical covariates were compared with Fisher’s exact test, while continuous covariates were compared with the Mann-Whitney-Wilcoxon test. Survival probabilities after BC were compared using the log-rank test. Results Out of 23 patients with myeloid BC, 14 (61%) had major route unbalanced ACA (n=10) or minor route unbalanced ACA (n=4), 4 had minor route balanced ACA and 5 patients had the translocation t(9;22)(q34;q11) or a variant translocation t(v;22) without ACA.13 out of 14 (93%) patients with lymphoid BC had major route unbalanced (n=10) or minor route unbalanced ACA (n=3) and 1 had the standard translocation t(9;22)(q34;q11) only. Between myeloid and lymphoid BC, the difference in the distribution of unbalanced ACA was apparent, but not statistically significant (p=0.06). The most frequently observed major route ACA was trisomy 8 in both groups (7 vs. 6), +der (22)t(9;22)(q34;q11) was more frequently found in myeloid than lymphoid BC (6 vs. 2), +19 was found in both phenotypes (3 vs. 3) whereas an isochromosome i(17)(q10) and an isoderivative chromosome ider(22)t(9;22)(q34;q11) were less frequent and found only in myeloid BC (1 for each vs 0 for each aberration). In lymphoid BC, 5 of 14 patients (36%) had ACA which involved chromosome 7 (del(7)(q22) and -7) whereas in myeloid BC only 2 patients (9%) had -7 (p=0.08). The balanced karyotype with a translocation t(3;21)(q26;q22) and the translocation t(9;11)(p22;q23) described in acute myeloid leukemia was observed in 3 patients with myeloid CML (2 and 1, respectively) and in none with lymphoid phenotype. No differences were observed in time to BC for patients with lymphoid vs. myeloid BC (p=0.31, median time: 409 vs. 453 days) and survival after onset of BC (p=0.9, median time: 544 vs. 284 days). Conclusions The proportion of unbalanced karyotypes was higher in lymphoid than in myeloid BC. In lymphoid BC alterations of chromosome 7 were more often present whereas +der(22)t(9;22)(q34;q11) was observed more frequently in myeloid BC. The reciprocal translocations t(3;21)(q26;q22) and t(9;11)(p22;q23) described in acute myeloid leukemias were only observed in myeloid BC. However these cytogenetic differences do not seem to alter the course of BC. Disclosures: Haferlach: MLL Munich Leukemia Laboratory: Employment, Equity Ownership. Hehlmann:Novartis: Research Funding; BMS: Consultancy, Research Funding. Hochhaus:Ariad: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; BMS: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria, Research Funding, Travel Other. Müller:Novartis: Honoraria, Research Funding, Speakers Bureau; BMS: Honoraria, Research Funding; Ariad: Honoraria. Saussele:Pfizer: Honoraria; BMS: Honoraria, Research Funding, Travel, Travel Other; Novartis: Honoraria, Research Funding, Travel Other.

Abstract: Abstract 781FN2 Introduction: Data on second line therapy with second generation tyrosine kinase inhibitors (TKI) in CML treatment were generated mainly from phase II/III industry initiated trials (Review Hehlmann Exp Op. 2011). 24-month overall survival (OS) varies between 88% and 94% after intolerance and/or resistance to imatinib for chronic phase (CP) and between 67% and 72% for accelerated phase (AP) or blast crisis (BC). Intention to treat analyses including outcome of patients after discontinuation of first line therapies have not been available as yet. We thought to evaluate overall and progression-free survival (OS and PFS) of imatinib intolerant vs. resistant patients under second line TKI with long-term follow-up within an investigator initiated trial. Methods: We analyzed data of the German CML study IV, a randomized 5-arm trial to optimize imatinib therapy on an intention to treat basis. According to protocol, follow-up of patients on and after second generation TKI after imatinib intolerance and/or resistance was continued for OS and PFS. Analysis of PFS was only relevant, if intolerance and resistance to imatinib therapy occurred while a patient was still in chronic phase (CP). Patients were censored at the time of allogeneic stem cell transplantation (allo-SCT). Results: From July 2002 to December 2010, 1,502 patients with Philadelphia chromosome and /or BCR-ABL positive CML in CP were randomized. 129 patients of the “imatinib after interferon arm” and 36 other patients had to be excluded (14 due to incorrect randomization or withdrawal of consent, 22 with missing baseline information). 1337 were randomized to primary imatinib treatment (imatinib 400 mg vs. imatinib 800 mg vs. imatinib in combination with either interferon alpha or araC). Of these, 234 (17%) discontinued imatinib therapy. 156 patients were treated with 2nd generation TKI, 61 were directly referred to allo-SCT, 17 patients received other regimens (including interferon alpha only or hydroxyurea). 120 of 156 patients started second generation TKI therapy (nilotinib, n=41, dasatinib, n=75, bosutinib, n=2, nilotinib and dasatinib, n=2) within 3 months after stopping imatinib, received treatment for at least one week and were evaluable for PFS and OS. 36 patients received second TKI later (median 10 months, range 3.5–61.4). Median age was 50 years (range 16–78), 42.5% were female. 48 patients were intolerant, 48 failed imatinib within CP and 24 after loss of CP (accelerated phase, n=10, blast crisis, n=14). Median time to second generation TKI was 17 months (range 1.4–97 months) and median follow-up after start of second-line TKI 31 months (range 0.2–71 months). Risk stratification according to the EUTOS Score was high in 20 patients (17%) and low in 94 patients (78%) and unknown in 6 patients (5%). OS for all 120 patients 3 years after start of second generation TKI was 73%, 96% for intolerant and 80% for resistant patients in CP and 19% for resistant patients in advanced disease (s. Fig. 1). According to EUTOS score, 3-year OS was 78% for low and 56% for high risk patients. Probability of PFS of the 96 patients in 1st CP after 3 years was 96% for intolerant and 76% for resistant patients. After 2nd generation TKI, 18 patients received an allo-SCT: all were in CP, 2 patients after imatinib intolerance, 16 patients after imatinib resistance. Conclusion: Survival on second generation TKI is high for imatinib intolerant patients in first CP but much lower for resistant patients in first CP or for patients with advanced disease phases. Alternative treatment strategies are warranted for these patient groups. Disclosures: Krause: Micromet: Research Funding. Kneba:Hoffmann La Roche: Honoraria. Hochhaus:Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Ariad: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. German CML Study Group:Deutsche Krebshilfe: Research Funding; Novartis: Research Funding; BMBF: Research Funding; EU: Research Funding; Roche: Research Funding; Essex: Research Funding.