Abstract: During the course of chronic myeloid leukemia (CML) progression to blast crisis (BC) is thought to be caused by genetic instability such as cytogenetic aberrations in addition to the translocation t(9;22)(q34;q11). We have shown previously that major route ACA indicate an unfavorable outcome (Fabarius et al., Blood 2011). We now investigate whether there is a correlation in time between appearance of major route ACA and increase in blast count. Methods: Cytogenetic data and blast count in the peripheral blood were available from 1,290 CML patients recruited to the German CML-studies III (621 patients) and IIIa (669 patients) from January 1995 to January 2004. Treatments were interferon-alpha-based or related allogeneic stem cell transplantation (HSCT). Presence of ACA and major route ACA was considered as a time-dependent covariate. Multivariate proportional hazards models were estimated taking Euro CML score, study III vs. IIIa and stem cell transplantability into account. Cumulative incidences of blast increases were calculated starting at the date of the first ACA or major route ACA, respectively, regarding death as a competing risk. Patients were censored at the date of HSCT with an unrelated donor. Results: 1,287 patients were evaluable with median observation times of 13 and 12 years and a 10-year survival of 48% and 61% in CML studies III and IIIa, respectively. 258 patients progressed to BC with a cumulative 10-year incidence of 20%. 195 patients displayed ACA during the course of disease. 45 patients (15.7%) showed ACA already at diagnosis. 44 patients showed unbalanced minor route, 29 balanced minor route aberrations, 23 -Y. 109 patients showed major route aberrations including 10 with other prior ACA. In a multivariate analysis on 1,257 patients, patients with ACA had a hazard ratio (HR) for a blast increase of between 2.0-2.2 (p 〈 0.001) for blast increases to ≥1%, ≥5%, ≥10%, ≥15%, ≥ 20% and ≥30% compared with patients without ACA (Table). When the same model was performed for major route ACA only at any time during disease, HRs of 2.2-2.7 (p 〈 0.001) were found. For ACA without major route ACA HRs were 1.6-2.1 (p 〈 0.001). In the multivariate analyses of major route ACA vs. no major route ACA a blast increase of 1-5% after diagnosis of major route ACA seems already indicative of progression. 5 years after the diagnosis of any ACA the cumulative incidence for a blast increase was 30% (95%- confidence interval (CI): 23-38%), of a major route ACA 40% (95%- CI: 28-49%). The 6-year probability of death without blast increase was 10%. 14 additional patients received an unrelated transplant of which 6 died. We conclude that ACA, particularly major route ACA, precede an increase of blasts. Major route ACA have to be considered as a prognostic indicator for disease progression at any time. Table 1. Blast increase to HR (univariate): ACA vs. no ACA HR(multivariate)*: ACA vs. no ACA HR (univariate): major route ACA vs. no major route ACA HR (multivariate)*: major route ACA vs. no major route ACA ≥30% 2.409 2.139 2.646 2.203 ≥20% 2.413 2.144 2.656 2.211 ≥15% 2.415 2.161 2.868 2.426 ≥10% 2.416 2.160 2.799 2.357 ≥5% 2.286 2.047 2.719 2.278 ≥1% 2.209 1.999 3.171 2.684 *adjusted to Euro-Score, study (III vs. IIIa) and transplantability Disclosures Saussele: ARIAD: Honoraria; BMS: Honoraria, Other: Travel grant, Research Funding; Pfizer: Honoraria, Other: Travel grant; Novartis Pharma: Honoraria, Other: Travel grant, Research Funding. Haferlach:MLL Munich Leukemia Laboratory: Employment, Equity Ownership. Scheid:Janssen-Cilag: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees. Baerlocher:Geron Corporation: Research Funding; Novartis: Research Funding. Schnittger:MLL Munich Leukemia Laboratory: Employment, Equity Ownership. Müller:BMS: Consultancy, Honoraria, Research Funding; Ariad: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria, Research Funding. Hochhaus:ARIAD: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding; Bristol-Myers Squibb: Honoraria, Research Funding; Novartis: Honoraria, Research Funding. Pfirrmann:BMS: Consultancy, Honoraria; Novartis Pharma: Consultancy, Honoraria. Baccarani:Bristol-Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; NOVARTIS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; ARIAD Pharmaceuticals, Inc.: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; PFIZER: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Hehlmann:BMS: Consultancy; Novartis Pharma: Research Funding.

Abstract: Background. The end phase or metamorphosis is one of the remaining challenges of chronic myeloid leukemia (CML) management. Blast crisis (BC) is a late marker. Earlier diagnosis may improve outcome. The detection of additional chromosomal abnormalities (ACA) at low blast levels might allow earlier treatment when outcome is better. Methods. We made use of 1536 Ph+CML-patients in chronic phase followed in the randomized CML study IV (Hehlmann et al, Leukemia 2017) for a median of 8.6 years. 1510 cytogenetically evaluable patients were analyzed for ACA and blast increase (Flow chart). According to impact on survival ACA were grouped into high-risk (+ 8; +Ph; i(17q); +17; +19 +21; 3q26; 11q23; -7; complex) and low-risk (all other). Prognosis with +8 alone was clearly better than with +8 accompanied by further abnormalities, but still worse than with low-risk ACA. +8 alone was therefore included in the high-risk group. The presence of high- and low-risk ACA was linked to 6 thresholds of blast increase (1%, 5%, 10%, 15%, 20%, and 30%) in a Cox proportional hazards model. Results. 139 patients (9.2%) displayed ACA at any time before BC diagnosis, 88 (5.8%) had high-risk and 51 (3.4%) low-risk ACA. ACA emerged after a median of 17 (0-133) months. 79 patients developed BC. 43 (61%) of 71 cytogenetically evaluable patients with BC had high-risk ACA. 3-year survival after emergence of high-risk ACA was 48%, after emergence of low-risk ACA 92%. At low blast levels (1-15%), high-risk ACA showed an increased hazard to die (ratios: 3.66 in blood; 6.84 in marrow) compared to no ACA in contrast to low-risk ACA. This effect was not observed anymore at blast increases to 20-30% (Figure). 38 patients with high-risk ACA died, 36 with known causes of death which were almost exclusively BC (n=26, 72%) and progression-related transplantation (n=8, 22%). Only 2 patients died of CML-unrelated causes. Conclusions. High-risk ACA herald death by BC already at low blast levels and may help to define CML end phase in a subgroup of patients at an earlier time than is possible with current blast thresholds. Cytogenetic monitoring is indicated when signs of progression surface and response to therapy is unsatisfactory. More intensive therapy may be indicated at emergence of high-risk ACA. Disclosures Hehlmann: Novartis: Research Funding. Haferlach:MLL Munich Leukemia Laboratory: Employment, Equity Ownership. Fabarius:Novartis: Research Funding. Krause:Siemens: Research Funding; Takeda: Honoraria; MSD: Honoraria; Gilead: Other: travel; Celgene Corporation: Other: Travel. Baerlocher:Novartis: Research Funding. Burchert:Novartis: Research Funding. Brümmendorf:Novartis: Consultancy, Research Funding; Janssen: Consultancy; Merck: Consultancy; Ariad: Consultancy; Pfizer: Consultancy, Research Funding; University Hospital of the RWTH Aachen: Employment. Hochhaus:Pfizer: Research Funding; Novartis: Research Funding; BMS: Research Funding; Incyte: Research Funding; MSD: Research Funding. Saussele:BMS: Honoraria, Research Funding; Incyte: Honoraria, Research Funding; Pfizer: Honoraria; Novartis: Honoraria, Research Funding. Baccarani:Novartis: Consultancy, Speakers Bureau; Incyte: Consultancy, Speakers Bureau; Takeda: Consultancy.

Abstract: Background Chronic myeloid leukemia (CML)-study IV was designed to explore whether treatment with imatinib (IM) at 400mg/day (n=400) could be optimized by doubling the dose (n=420), adding IFN (n=430) or cytarabine (n=158) or using IM after IFN-failure (n=128). Methods From July 2002 to March 2012, 1551 newly diagnosed patients in chronic phase were randomized into a 5-arm study. The study was powered to detect a survival difference of 5% at 5 years. The impact of patients' and disease factors on survival was prospectively analyzed. At the time of evaluation, at least 62% of patients still received imatinib, 26.2% were switched to 2nd generation tyrosine kinase inhibitors. Results After a median observation time of 9.5 years, 10-year overall survival was 82%, 10-year progression-free survival 80% and 10-year relative survival 92%. In spite of a faster response with IM800mg, the survival difference between IM400mg and IM800mg was only 3% at 5 years. In a multivariate analysis, the influence on survival of risk-group, major-route chromosomal aberrations, comorbidities, smoking and treatment center (academic vs. other) was significant in contrast to any form of initial treatment optimization. Patients that reached the response milestones 3, 6 and 12 months, had a significant survival advantage of about 6% after 10 years regardless of therapy. The progression probability to blast crisis was 5.8%. Blast crisis was proceeded by high-risk additional chromosomal aberrations. Conclusions For responders, monotherapy with IM400mg provides a close to normal life expectancy independent of the time to response. Survival is more determined by patients' and disease factors than by initial treatment selection. Although improvements are also needed for refractory disease and blast crisis, more life-time can currently be gained by carefully addressing non-CML determinants of survival. Disclosures Hehlmann: Novartis: Research Funding; BMS: Consultancy. Saussele: Pfizer: Honoraria; Incyte: Honoraria; Novartis: Honoraria, Research Funding; BMS: Honoraria, Research Funding. Pfirrmann: BMS: Honoraria; Novartis: Honoraria. Krause: Novartis: Honoraria. Baerlocher: Novartis: Honoraria; BMS: Honoraria; Pfizer: Honoraria. Bruemmendorf: Novartis: Research Funding. Müller: Novartis: Honoraria, Research Funding; BMS: Honoraria, Research Funding; Ariad: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding. Jeromin: MLL Munich Leukemia Laboratory: Employment. Hänel: Roche: Honoraria; Novartis: Honoraria. Burchert: BMS: Honoraria. Waller: Mylan: Consultancy, Honoraria. Mayer: Eisai: Research Funding; Novartis: Research Funding. Link: Novartis: Honoraria. Scheid: Novartis: Honoraria. Schafhausen: Novartis: Honoraria; BMS: Honoraria; Pfizer: Honoraria; Ariad: Honoraria. Hochhaus: Incyte: Research Funding; MSD: Research Funding; Pfizer: Research Funding; Novartis: Research Funding; BMS: Research Funding; ARIAD: Research Funding.

Abstract: 7049 Background: It is unclear whether IM 400 mg is the optimum choice for the successful treatment of CML. Treatment optimization was therefore attempted. Methods: From July 2002 to March 2012, 1551 newly diagnosed patients in chronic phase (CP) were randomized into a 5-arm study to analyze 2 IM doses and 3 combinations. 1536 patients were evaluable, 400 for IM 400 mg, 420 for IM 800 mg, 430 for IM + Interferon (IFN), 158 for IM + Ara C and 128 for IM after IFN. Recruitment to the latter two arms was stopped after a pilot phase. Results: 10-year overall survival (OS) of all patients was 82%, 10-year progression free survival (PFS) 80%. 10-year OS was 80% with IM 400 mg, 79% with IM 800 mg, 84% with IM + IFN, 84% with IM + Ara C and 79% with IM after IFN. The differences were not significant. 10-year PFS was 80% with IM 400mg, 77% with IM 800mg, 83% with IM + IFN, 82% with IM + Ara C and 75% with IM after IFN. The differences were not significant either. Survival with any treatment was not significantly different from IM 400mg at any risk level by any risk score (Euro Sokal, EUTOS, ELTS). 87 patients progressed to blast crisis (BC). The 10-year cumulative incidence of BC was 5.8% (95% CI: 4.7%; 7.1%) equally distributed across treatment arms. Most BC occurred in the first 2 years. Median survival after BC was 7.9 months across treatment arms. 275 patients have died, 23 after stem cell transplantation in first CP. Two thirds of deaths were unrelated to CML. Incidence of death due to CML by competing risk analysis with death unrelated to CML as competing risk was not different between the 5-treatment arms. 10-year relative survival probability was 92% when compared to matched general population data. Patients reaching the cytogenetic or molecular response landmarks according to European LeukemiaNet criteria ( 〈 10% BCR-ABL IS at 3 months, 〈 1% BCR-ABL IS or complete cytogenetic remission at 6 months, 〈 0.1% BCR-ABL IS (MMR) at 12 months) had a significantly better survival than those not reaching the landmarks regardless of therapy. Conclusions: In conclusion, outcome of CML is currently more determined by prognostic markers than by choice of therapy. IM400 mg remains an excellent choice for initial therapy of CP-CML. Clinical trial information: NCT00055874.

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: Blast crisis is one of the remaining challenges in chronic myeloid leukemia (CML). Whether additional chromosomal abnormalities (ACAs) enable an earlier recognition of imminent blastic proliferation and a timelier change of treatment is unknown. One thousand five hundred and ten imatinib-treated patients with Philadelphia-chromosome-positive (Ph+) CML randomized in CML-study IV were analyzed for ACA/Ph+ and blast increase. By impact on survival, ACAs were grouped into high risk (+8, +Ph, i(17q), +17, +19, +21, 3q26.2, 11q23, −7/7q abnormalities; complex) and low risk (all other). The presence of high- and low-risk ACAs was linked to six cohorts with different blast levels (1%, 5%, 10%, 15%, 20%, and 30%) in a Cox model. One hundred and twenty-three patients displayed ACA/Ph+ (8.1%), 91 were high risk. At low blast levels (1–15%), high-risk ACA showed an increased hazard to die compared to no ACA (ratios: 3.65 in blood; 6.12 in marrow) in contrast to low-risk ACA. No effect was observed at blast levels of 20–30%. Sixty-three patients with high-risk ACA (69%) died ( n  = 37) or were alive after progression or progression-related transplantation ( n  = 26). High-risk ACA at low blast counts identify end-phase CML earlier than current diagnostic systems. Mortality was lower with earlier treatment. Cytogenetic monitoring is indicated when signs of progression surface or response to therapy is unsatisfactory.