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: Background In newly diagnosed acute myeloid leukemia (AML), the general recommendation is to start treatment immediately after the diagnosis has been made. This paradigm is based both on the observation that untreated acute leukemia has a poor prognosis and on retrospective analyses demonstrating a shorter survival in younger AML patients (pts) in whom treatment was delayed by more than 5 days (Sekeres et al., 2009). A more recent single-center analysis came to a different conclusion, showing no prognostic effect for the time from diagnosis to treatment (TDT; Bertoli et al., 2013). We explored the relationship between TDT and prognosis on a large set of real-world data from the AML registry of the Study Alliance Leukemia (SAL) and compared it to the published cohorts. Methods The SAL runs a transregional AML registry in 46 treatment centers across Germany (NCT03188874). All registered patients with an intensive induction treatment, a minimum follow-up time of 12 months and no acute promyelocytic leukemia were selected (n=2,200). Treatment start was defined by the first day of cytarabine, whereas single agent hydroxyurea (HU) was labeled as pretreatment. We analyzed the influence of TDT on complete remission (CR), early death (ED) and overall survival (OS) in univariable analyses for each day of treatment delay, in groups of 0-5, 6-10, 11-15 and & gt;15 days of TDT, and by using the restricted cubic spline (RCS) method for data modelling. In order to adjust for the influence of established prognostic variables on the outcomes, we used multivariable regression models and propensity score weighting. The influence of HU pretreatment on outcomes was investigated by introducing an interaction term between TDT and the presence of HU pretreatment. Results The median age was 59 years (y) (IQR 50-68), the proportion of pts with favorable, intermediate and adverse genetic risk according to ELN was 27%, 53%, and 20%; & gt;95% of pts received induction treatment with standard 7+3. HU pretreatment was administered in 4% of pts. The median TDT was 3 days (IQR 2-6). Descriptive statistics after grouping of pts showed the highest median age and the lowest proportion of NPM1 mutated and favorable risk in the TDT group 11-15. Of all pts, 79% achieved a CR/CRi; unadjusted CR rates for the patient groups with TDT of 0-5, 6-10, 11-15 and & gt;15 days were 80%, 77%, 74% and 76%, respectively (p=0.317). In multivariable analysis accounting for the influence of ELN risk, age, WBC, LDH, de novo versus secondary AML and ECOG, the OR for each additional day of TDT was 0.99 (95%-CI, 0.97-1.00; p=0.124). Four percent of pts died within the first 30 days from treatment start. The respective rates in the four TDT categories were 4.0%, 3.8%, 5.1% and 4.1% (p=0.960). In multivariable analysis, the OR for TDT was 1.01 (95%-CI, 0.98-1.05; p=0.549). After a median follow-up of 40 months, the 2-y OS of all pts was 51%. The unadjusted 2-y OS rates stratified by TDT of 0-5, 6-10, 11-15, & gt;15 days were 52, 49, 46, and 51% (see Table 1 and Figure 1). The hazard ratio (HR) for each day of treatment delay was 1.00 (95%-CI; 0.99-1.01; p=0.317). In multivariable Cox regression analysis, the HR for TDT as continuous variable was 1.00 (95%-CI, 0.99-1.01; p=0.689). When OS was analyzed separately stratified for age ≤60 and & gt;60 ys and for high versus lower initial WBC defined by a threshold of 50 x 109/L, no significant differences between TDT groups were observed. Multivariable models using TDT as a grouped variable or with RCS did not provide evidence for a significant influence of TDT on outcomes. Propensity score matching of pts in the four TDT groups did not reveal an influence on outcomes. The use of HU was not associated with CR, ED nor OS. Conclusion Our study on 2,200 newly diagnosed registry pts receiving consistent intensive induction with standard-dose cytarabine plus daunorubicin (7+3) suggests that TDT is not related to response or survival, neither in younger nor in older pts. Despite multivariable analyses, a bias towards longer TDT intervals in pts judged to be clinically stable by the treating physician cannot be excluded entirely. As treatment stratification in intensive first-line treatment of AML evolves, the TDT data suggests that it may be a safe and reasonable approach to wait for genetic and other laboratory test results in order to assign clinically stable pts to the best available treatment option before the start of intensive treatment. Disclosures Krämer: Daiichi-Sankyo: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bayer: Research Funding; BMS: Research Funding; Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Hänel:Roche: Honoraria; Amgen: Honoraria; Celgene: Other: advisory board; Novartis: Honoraria; Takeda: Other: advisory board. Jost:Daiichi: Honoraria; Sanofi: Honoraria; Gilead: Other: travel grants; Jazz Pharmaceuticals: Honoraria. Brümmendorf:Merck: Consultancy; Janssen: Consultancy; Novartis: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; University Hospital of the RWTH Aachen: Employment; Ariad: Consultancy. Krause:Siemens: Research Funding; Takeda: Honoraria; MSD: Honoraria; Gilead: Other: travel; Celgene Corporation: Other: Travel. Scholl:Novartis: Other: Project funding; Pfizer: Other: Advisory boards; Gilead: Other: Project funding; Daiichi Sankyo: Other: Advisory boards; AbbVie: Other: Advisory boards. Hochhaus:Pfizer: Research Funding; Novartis: Research Funding; BMS: Research Funding; Incyte: Research Funding; MSD: Research Funding. Kiani:Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Middeke:Sanofi: Research Funding, Speakers Bureau; Roche: Speakers Bureau; AbbVie: Consultancy, Speakers Bureau; Gilead: Consultancy; Janssen: Consultancy, Speakers Bureau; MSD: Consultancy. Thiede:AgenDix GmbH: Employment, Equity Ownership; Novartis: Research Funding, Speakers Bureau; Bayer: Research Funding; Daiichi-Sankyo: Speakers Bureau. Stoelzel:JAZZ Pharmaceuticals: Consultancy; Neovii: Other: Travel funding; Shire: Consultancy, Other: Travel funding. Platzbecker:Celgene: Consultancy, Honoraria, Research Funding; Abbvie: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Research Funding.

Abstract: Introduction: Chronic myeloid leukemia (CML) is a clonal stem cell disorder characterized by the bcr-abl translocation. Recent data provides evidence that CML chronic phase (CP) can be classified into early and late CP depending on the degree of expansion of the leukemic stem cell (LSC) clone. Patients in late CP have a higher LSC burden going along with an inferior response to TKI therapy. Telomeres shorten with each cell division and telomere length (TL) reflects the replicative history of a cell. We postulate that the LSC burden correlates with accelerated telomere shortening due to clonal replicative expansion of bcr-abl positive cells. Previous studies evaluating TL in peripheral blood cells of CML patients already revealed a correlation of age-adapted TL with disease stage, response to treatment and duration of CP. However, the high intra-individual, mostly genetic inter-individual variability in TL limits the predictive value of TL measurements when no patient specific bcr-abl negative cells were available for comparison. The aim of our study was to analyze TL in the LSC and non-clonal HSC compartment of patients with CP using a modified Q-FISH technique allowing the TL analysis in bcr-abl positive and negative cells. Methods and Patients: 11 patients diagnosed with CML in CP of the NCT00852566 study (Nordic CML Group) were included into our retrospective analysis. Mean age of the patients was 58.9 years. Bone marrow samples from initial diagnosis were sorted for CD34+/CD38- cells reflecting the leukemic stem cell compartment. Samples were analyzed with the FISH method using dual fusion dual color BCR-ABL1 probe following standard procedures. After capturing the bcr-abl staining using confocal microscopy, samples were re-processed for TL analysis by Q-FISH using established protocols. Optimized microscopy techniques allowed for TL to be assessed in all previously captured cells allowing the identification of bcr-abl positive and negative cells within the same sample. Analysis and quantification of bcr-abl FISH staining and TL measurement by Q-FISH were performed in single-blinded fashion. Results: Bcr-abl negative cells represent the non-clonal hematopoiesis and were used to correct TL. We observed significant shortened TL in the bcr-abl positive cells compared to bcr-abl negative cells (-2.18 ± 2.08 kilobases (kb), p=0.01) in line with previously published results. Next, we correlated the clone size (i.e. the proportion of bcr-abl positive cells) with the degree of telomere shortening in the leukemic stem cell compartment. Mean clone size of the patients was 67.4 ± 21.7 % S.D. Despite of the relatively small sample size studied, we found a significant negative correlation (R²=0.45, p=0.04) between TL and clone size strongly supporting the notion that increased expansion of the bcr-abl positive LSC pool leads to accelerated telomere shortening. Conclusions: In this study, we provide evidence for accelerated telomere shortening in bcr-abl positive LSC as compared to their normal CD34+/CD38- counterpart in CP CML samples at diagnosis. Furthermore, the degree of TL shortening correlates with the clone size in the HSC compartment, i.e. a parameter that reflects duration of CP. Thus, this allows the discrimination of early vs. late CP and might as such be used as a prognostic (and potentially predictive) biomarker in CML. Disclosures Richter: Novartis: Honoraria, Research Funding; BMS: Honoraria, Research Funding; Ariad: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding. Fioretos:Cantargia: Equity Ownership. Mustjoki:Ariad: Research Funding; Bristol-Myers Squibb: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding; Novartis: Honoraria, Research Funding. Brümmendorf:Pfizer: Consultancy, Honoraria; Bristol-Myers Squibb: Consultancy, Honoraria; Ariad: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Research Funding; Patent on the use of imatinib and hypusination inhibitors: Patents & Royalties.

Abstract: TL in LSCs is significantly shortened at diagnosis of CML and correlates with LSC burden. TL in nonleukemic myeloid cells in deep molecular remission is unaffected by long-term TKI treatment.

Abstract: Introduction: The single nucleotide polymorphism (SNP) rs460089 (G/C) located in the promotor of SLC22A4 (transporter hOCTN1) was identified as a prognostic factor for the outcome of chronic myeloid leukaemia patients treated with imatinib first line (Jaruskova et al. JECCR 2017). Patients with GC genotype had significantly higher probability of achievement of sustained major molecular response (MMR, BCR-ABL≤0.1% IS) as compared with patients with GG. We investigated differences in the outcome after imatinib cessation in EURO-SKI patients according to the genotypes of the SNP rs460089. Methods: DNA analysis was performed by TaqMan SNP genotyping assay using StepOnePlus RQ-PCR System (Thermofisher Scientific). In addition to the inclusion criteria defined for prognostic analysis in Saussele et al. (Lancet Oncology 2018), all patients with interferon pre-treatment were excluded. Data on sex, duration of IM treatment, of deep molecular response and age at time of imatinib discontinuation as well as molecular status at 6 months thereafter were available for 178 patients. Logistic regression was used to investigate factors affecting MMR maintenance at 6 months. Level of significance was 0.05. Results: Of 178 patients, 106 (60%) maintained MMR 6 months after imatinib stop. GC genotype was identified in 64 patients, GG in 96 and CC in 18. Most beneficial for MMR maintenance was genotype GC (72%, 95% confidence interval (CI): 60-82%), followed by CC (61%, CI: 38-80%) and GG (51%, CI: 41-61%). Overall, the SNP rs460089 was associated with MMR maintenance (p=0.0335) with a significantly higher odds ratio (OR) for maintenance for GC genotype vs. GG (2.451, CI: 1.247-4.819, p=0.0093) but not for CC vs. GG (1.507, CI: 0.539-4.216, p=0.4343). Only duration of TKI treatment was significant (OR: 1.157, CI: 1.014-1.319, p=0.0303) when added to genotypes in multiple regression. The OR of GC vs. GG was slightly modified to 2.311 (1.164-4.588, p=0.0166). Conclusions: Based on observed data we suppose that the GC genotype of the SNP rs460089 is associated with sufficient intracellular concentration of imatinib allowing more efficient targeting of CML cells during the treatment. This resulted in a higher proportion of patients who sustained MMR after imatinib stop as compared with patients with GG. Longer duration of imatinib treatment increased the probability of MMR maintenance after imatinib cessation also in patients with GG. The frequency of CC was low and outcome in between GC and GG. The SNP rs460089 may provide an independent prognostic factor for molecular response maintenance after imatinib cessation. Supported by MZCR 00023736. Disclosures Machova: Novartis: Consultancy; BMS: Consultancy, Research Funding; Incyte: Consultancy. Fabarius:Novartis: Research Funding. Brümmendorf:Pfizer: Consultancy, Research Funding; University Hospital of the RWTH Aachen: Employment; Merck: Consultancy; Ariad: Consultancy; Novartis: Consultancy, Research Funding; Janssen: Consultancy. Burchert:Novartis: Research Funding. Mustjoki:BMS: Honoraria, Research Funding; Novartis: Research Funding; Pfizer: Research Funding. Mayer:AOP Orphan Pharmaceuticals AG: Research Funding. Žáčková:Bristol Myers Squibb: Consultancy; Angelini: Consultancy; Incyte: Consultancy; Novartis: Consultancy. Panayiotidis:Bayer: Other: Support of clinical trial. Richter:Novartis: Consultancy; Pfizer: Consultancy, Research Funding. Hjorth-Hansen:BMS: Research Funding; Pfizer: Consultancy, Research Funding; Austrian Orphan Pharma: Consultancy, Research Funding. Saussele:Novartis: Honoraria, Research Funding; BMS: Honoraria, Research Funding; Pfizer: Honoraria; Incyte: Honoraria, Research Funding.

Abstract: Background: Patients with AML who are not eligible for intensive therapy or stem cell transplantation have a dismal prognosis. Autocrine and paracrine secretion of angiogenic and hematopoietic growth factors such as vascular endothelial growth factor in the bone marrow (BM) microenvironment may promote proliferation and survival of leukemic blasts. The oral multikinase inhibitor pazopanib was reported to exert growth inhibitory and proapoptotic effects in myeloid cells. Methods: This phase II study evaluated pazopanib (800 mg orally once daily) in patients with relapsed or refractory AML or at initial diagnosis when no intensive treatment is possible. All patients who received pazopanib for 14 days or longer were included into the analysis of safety, tolerability and efficacy. Response criteria are defined according to the Revised Recommendations of the International Working Group for Diagnosis, Standardization of Response Criteria, Treatment Outcomes, and Reporting Standards for Therapeutic Trials in Acute Myeloid Leukemia. Co-primary endpoints were cumulative response rate (CR, CRp, CRi, PR) within up to one year and reduction of BM microvessel density (MVD) on day 28. Overall survival (OS) and progression free survival (PFS, time from first dose until progression or death from any cause) were measured from the first day of treatment until death of any cause or progression of disease. Results: Between February 2012 and September 2015, 20 AML patients with a median (range) age of 76 (52 - 86) years were treated with pazopanib. The majority of patients (n = 15, 75%) had relapsed (n = 7) or refractory (n = 8) AML, five patients (25%) were enrolled with newly diagnosed AML. Median (range) ECOG performance status was 1 (1 - 3). According to ELN 2010 criteria, four patients (20%) had adverse risk, 15 (75%) had intermediate risk, and one patient (5%) had favorable cytogenetic/molecular risk. Overall, the safety profile of pazopanib was similar to that reported in previous studies. The most common AEs of any grade, related to pazopanib as assessed by the investigator, were gastrointestinal AEs, including nausea (n = 8), diarrhea (n = 6), inappetence (n = 5) and vomiting (n = 3). Two out of 20 treated patients (10%) had a partial remission (reduction of blast count 〉 50%) and 14 (70%) a stable disease (SD) while on pazopanib. Four patients (20%) experienced initial PD. Median PFS was 65 days (95% CI 29 - 105). After the end of study period three remarkable responses occurred on subsequent therapies such as demethylating agents resulting in one CRi and one CRp and one CR after secondary BM transplantation. All these patients had SD while on pazopanib and improved general condition allowing escalation of therapy. However, at the time of OS evaluation all patients had died due to PD and/or infections. Median OS of the treated study cohort was 191 days (95% CI 87 - 435), and 1-year survival altogether was 35%. There was no significant change in BM MVD between day 1 and day 28. Conclusion: Pazopanib was found to be safe in patients with AML not eligible for intensive therapy. The survival data are encouraging but clearly necessitate a controlled randomized clinical trial for confirmation. Clinical trial information: NCT01361334. Disclosures Stelljes: Amgen: Honoraria; JAZZ: Honoraria; MSD: Consultancy; Pfizer: Consultancy, Honoraria, Research Funding; Novartis: Honoraria. Lenz:Roche: Consultancy, Honoraria, Other: Travel, Accomodations, Expenses, Research Funding; Bayer: Consultancy, Honoraria, Research Funding, Speakers Bureau; Novartis: Research Funding; Gilead: Consultancy, Honoraria; Janssen: Consultancy, Honoraria, Other: Travel, Accomodations, Expenses, Research Funding, Speakers Bureau; Celgene Corp.: Consultancy, Honoraria, Other: Travel, Accomodations, Expenses, Research Funding, Speakers Bureau. Brümmendorf:Takeda: Consultancy; Novartis: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Janssen: Consultancy; Merck: Consultancy.

Abstract: Background: Tyrosine kinase inhibitors (TKIs) used in the treatment of chronic myeloid leukemia (CML) are not entirely selective for the BCR-ABL1 kinase but also inhibit a variety of other kinases, sometimes triggering unpredicted biological effects. As an example, the TKIs dasatinib and bosutinib both inhibit Src-kinases, which are important mediators of T-cell function. Earlier in vitro data has shown that dasatinib can suppress activation and proliferation of T and NK cells, but it can also elicit signs of immunostimulation in patients, including rapid mobilization of lymphocytes and LGL lymphocytosis. No extensive analyses of the immunological in vivoeffects of bosutinib have been performed thus far. Therefore, we aimed at characterizing T and NK cell phenotypes and functional features in CML patients in a clinical setting in the context of first-line bosutinib and imatinib treatment. Methods:Peripheral blood samples were obtained from newly diagnosed CML CP patients enrolled in the BFORE clinical trial (NCT02130557), receiving bosutinib (n=13) or imatinib (n=20) as frontline TKI treatment. Samples were drawn at diagnosis and following 3 and 12 months of therapy. Detailed immunophenotyping of NK and T cells was performed with multicolor flow cytometry. In addition, mononuclear cells were used to study the function of NK and T cells (CD107ab degranulation upon stimulation with K562 cells and detection of IFN-γ/TNF-α secretion after stimulation with anti-CD3/anti-CD28 antibodies, respectively). Moreover, blood differential counts were taken before and 2 hours after drug intake at 3 and 12 months to examine the direct effects on lymphocyte counts (mobilization). Results: No significant changes were observed in absolute white blood cell or lymphocyte counts directly (2 hours) after bosutinib or imatinib intake, in contrast to what has been observed in dasatinib treated patients. Analysis of T cell subsets during bosutinib treatment revealed that the proportion of CD4+ cells increased after the start of treatment (median dg. 60.0% vs. 3 months 62.0% p=0.06; vs. 12 months 72.8% p=0.03), but no significant changes were observed in the phenotype. Correspondingly, the proportion of CD8+ T-cells decreased moderately (dg. 31.6% vs. 3 months 25.5% p=0.01) after the therapy start. Interestingly, the proportion of PD1+ (dg. 19.6% vs. 3 months 11.9%, p=0.06; vs. 12 months 14.3%, p=0.11) and DNAM+ CD8+ T-cells decreased (dg. 73.1% vs. 3 months 66.2% p=0.004; vs. 12 months 64.6% p=0.02). No changes in the cytokine production of any of the studied subgroups of T-cells was observed. Moreover, the proportion, phenotype and function of NK-cells were not affected by bosutinib treatment. In contrast, during imatinib treatment the proportion of CD56+CD16+ NK-cells significantly increased (dg 4.3% vs. 3 months 9.9% p=0.0005; vs 12 months 14.4% p=0.002; 8.1% in bosutinib treated patients). Moreover, in imatinib patients NK-cells downregulated CD27 (dg 9.0% vs. 3 months 5.2% p=0.004; vs. 12 months 4.9%; p=0.002). Further, NK-cells from imatinib-treated patients expressed more CD107ab upon stimulation with K562 at 3 and 12 months, when compared to samples from diagnosis (dg 13.0% vs. 3 months 16.1%, p=0.01; vs. 12 months 23.2%, p=0.008). The proportion of CD4+ T-cells increased 3 months after the start of imatinib treatment (dg 60.1% vs. 3 months 63.5% p=0.01), whereas the percentage of CD8+ T-cells decreased (dg. 38.6% vs. 3 months 31.5% p=0.02). Decreased expression of DNAM (dg 73.5% vs. 3 months 67.9% p=0.0008; vs. 12 months 62.4% p=0.002) was observed in the CD4+ T-cells. Similarly as in bosutinib treated patients, the proportion of PD1+ CD8+ cells decreased during imatinib treatment (dg 18.2% vs. 3 months 14.7%, p=0.02; vs. 12 months 14.8%, p=0.03). Both CD4+ and CD8+ T-cell subsets from imatinib-treated patients secreted less cytokines after the start of treatment when compared to the pre-treatment samples. Conclusions: Despite of the Src-kinase inhibitory profile of bosutinib, no major changes were observed in T- or NK-cell phenotype or function during first-line bosutinib treatment. In contrast, in imatinib treated patients the proportion of NK-cells increased and their degranulation responses were significantly higher than in untreated CML patients. Comparison of these data with the clinical variables and treatment outcome is warranted. Disclosures Stentoft: Novartis: Research Funding; Bristol-Myers-Squibb: Research Funding; Pfizer: Research Funding; Ariad: Research Funding. Gjertsen:BerGenBio AS: Consultancy, Research Funding. Janssen:Pfizer: Honoraria; Novartis: Research Funding; Ariad: Honoraria; BMS: Honoraria. Brümmendorf:Pfizer: Research Funding; Novartis: Research Funding. Richter:BMS: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Ariad: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding. Mustjoki:Pfizer: Honoraria, Research Funding; Ariad: Research Funding; Bristol-Myers Squibb: Honoraria, Research Funding; Novartis: Honoraria, Research Funding.

Abstract: In fit patients with newly diagnosed acute myeloid leukemia (AML), immediate treatment start is recommended due to the poor prognosis of untreated acute leukemia. We explored the relationship between time from diagnosis to treatment start (TDT) and prognosis in a large real-world data set from the German Study Alliance Leukemia–Acute Myeloid Leukemia (SAL-AML) registry. All registered non–acute promyelocytic leukemia patients with intensive induction treatment and a minimum 12 months of follow-up were selected (n = 2263). We analyzed influence of TDT on remission, early death, and overall survival (OS) in univariable analyses for each day of treatment delay, in groups of 0 to 5, 6 to 10, 11 to 15, and & gt;15 days of TDT, adjusted for influence of established prognostic variables on outcomes. Median TDT was 3 days (interquartile range, 2-7). Unadjusted 2-year OS rates, stratified by TDT of 0 to 5, 6 to 10, 11 to 15, and & gt;15 days, were 51%, 48%, 44%, and 50% (P = .211). In multivariable Cox regression analysis accounting for established prognostic variables, the TDT hazard ratio as a continuous variable was 1.00 (P = .617). In OS analyses, separately stratified for age ≤60 and & gt;60 years and for high vs lower initial white blood cell count, no significant differences between TDT groups were observed. Our study suggests that TDT is not related to survival. As stratification in intensive first-line AML treatment evolves, TDT data suggest that it may be a feasible approach to wait for genetic and other laboratory test results so that clinically stable patients are assigned the best available treatment option. This trial was registered at www.clinicaltrials.gov as #NCT03188874.

Abstract: Introduction: Tyrosine kinase inhibitor therapy has been associated with cardiovascular (CV) events. BOS is approved for patients (pts) with newly diagnosed Philadelphia chromosome-positive (Ph+) chronic phase (CP) CML and Ph+ CML resistant/intolerant to prior therapy. We analyzed cardiac, vascular and hypertension treatment-emergent adverse events (TEAEs) in pts with newly diagnosed CP CML receiving BOS or IMA after 5 yrs follow-up in BFORE. Methods: In the open-label, phase 3 BFORE trial (NCT02130557), 536 pts with newly diagnosed CP CML were randomized 1:1 to receive first-line 400 mg once-daily BOS (n=268) or IMA (n=268; 3 untreated). The current analysis included all pts who received ≥1 dose of study drug. TEAEs were monitored from first dose of study drug until 28 d after last dose; monitoring of non-serious adverse events (AE) ended at the start of a new cancer treatment. Prespecified MedDRA terms (cardiac, n=133; vascular, n=502) comprised clusters of investigator-assessed TEAEs (Table). Multivariable proportional subdistribution hazard models predicting time to first TEAE included treatment group; baseline demographic information; history of cardiac events, vascular events, hypertension, diabetes, hyperlipidemia, and tobacco use; as well as hypertension, cardiac (for vascular model) and vascular (for cardiac model) TEAEs. CI excluding 1 was considered predictive of outcome. This analysis was based on 17-Apr-20 last pt last visit (12-Jun-20 database lock), 5 y (240 wks) after last enrolled pt. Results: At study completion, 59.7% of BOS pts and 58.1% of IMA pts were still on treatment. Median duration of treatment was 55 mo for pts receiving BOS or IMA; respective median (range) dose intensity was 393.6 (39-583) vs 400.0 (189-765) mg/d. In the BOS vs IMA arm, 57.8% vs 56.2% of pts had ≥1 CV risk factor at baseline; 20.9% vs 17.7% had ≥3 risk factors, respectively. The most common risk factors were a history of hypertension (BOS, 34.0%; IMA, 30.6%), BMI & gt;30 (BOS, 23.1%; IMA, 21.9%), age ≥65 y (BOS, 19.8%; IMA, 17.4%), and history of hyperlipidemia (BOS, 16.8%; IMA, 18.9%). Rates of cardiac, vascular and hypertension TEAEs; serious adverse events (AEs); AEs leading to treatment withdrawal and drug-related TEAEs (per investigator) were low in both arms (Table). Exposure-adjusted rates of cardiac, vascular and hypertension TEAEs were similar between arms (Table). Risk factors for cardiac TEAEs (HR; 95% CI) were age in years (1.04 [1.02-1.07]), race other than Asian or black compared to white ( & lt;0.01 [ & lt;0.01- & lt;0.01]), a history of tobacco use (6.94 [1.89-25.40] ) and cardiac events (3.59 [1.68-7.65]), hypertension (3.07 [1.20-7.84] ) and vascular TEAEs (5.27 [1.53-18.18]). Risk factors for vascular TEAEs (HR [95% CI] ) were black race compared to white ( & lt;0.01 [ & lt;0.01- & lt;0.01]), a history of vascular events (4.65 [1.81-11.97] ) and cardiac TEAEs (7.73 [2.31-25.84]). In multivariable analyses, treatment group was not predictive of time to initial cardiac (HR 0.87 [95% CI 0.45-1.70] ) or vascular (HR 2.17 [95% CI 0.94-45.04) TEAEs. The most common cardiac, vascular, and hypertension TEAEs, respectively, were sinus bradycardia (2.2%), angina pectoris (3.0%) and hypertension (9.7%) with BOS vs electrocardiogram QT prolongation (3.8%), peripheral coldness (1.1%) and hypertension (10.9%) with IMA. One grade 5 cardiac (acute cardiac failure) and one vascular (myocardial ischemia) TEAE were reported with BOS, and one vascular (cerebrovascular accident) TEAE with IMA; none were considered related to study drug. Successful treatment rechallenge was achieved in the majority of pts with dose interruptions due to cardiac (BOS, 85.7%; IMA, 100%) and vascular (BOS, 100%; IMA, not applicable) TEAEs who were readministered study drug. No pts had dose interruptions due to hypertension TEAEs. Cardiac, vascular and hypertension TEAEs resolved in 57.7%, 75.0% and 35.7% of pts receiving BOS and 65.2%, 66.7% and 48.3% receiving IMA. Conclusions: In this final analysis of BFORE, the incidence of cardiac, vascular, and hypertension TEAEs in pts with newly diagnosed CP CML receiving BOS or IMA was low and was similar between treatment groups. These AEs infrequently led to treatment discontinuation. In addition to continued improved efficacy with BOS vs IMA after 5 yrs follow-up (Brümmendorf et al., ASH 2020), these safety results support the use of first-line BOS as a standard of care in pts with CP CML. Disclosures Cortes: Bristol-Myers Squibb: Research Funding; BiolineRx: Consultancy, Research Funding; Takeda: Consultancy, Research Funding; BioPath Holdings: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Consultancy, Research Funding; Amphivena Therapeutics: Research Funding; Arog: Research Funding; Jazz Pharmaceuticals: Consultancy, Research Funding; Telios: Research Funding; Astellas: Research Funding; Sun Pharma: Research Funding; Merus: Research Funding; Daiichi Sankyo: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Immunogen: Research Funding. le Coutre:Incyte: Honoraria; Pfizer: Honoraria; Novartis: Honoraria. Gambacorti-Passerini:Bristol-Myers Squibb: Consultancy; Pfizer: Honoraria, Research Funding. Hjorth-Hansen:Pfizer: Honoraria, Research Funding; Austrian Orphan Pharma: Honoraria, Research Funding; Bristol-Myers Squibb: Research Funding. Garcia-Gutiérrez:Novartis: Consultancy, Other: Travel, Accommodation, Expenses, Research Funding; Bristol-Myers Squibb: Consultancy, Other: Travel, Accommodation, Expenses, Research Funding; Pfizer: Consultancy, Other: Travel, Accommodation, Expenses, Research Funding; Incyte: Consultancy, Other: Travel, Accommodation, Expenses, Research Funding. Kota:Ariad: Honoraria; Incyte: Honoraria; Xcenda: Honoraria; Novartis: Consultancy, Honoraria; Millennium Pharmaceuticals, Inc., a wholly owned subsidiary of Takeda Pharmaceutical, Company Ltd, Cambridge, MA, USA: Honoraria; Pfizer: Consultancy, Honoraria. Purcell:Pfizer: Current Employment, Current equity holder in publicly-traded company. Viqueira:Pfizer: Current Employment, Current equity holder in publicly-traded company. Leip:Pfizer: Current Employment, Current equity holder in publicly-traded company. Brümmendorf:Takeda: Consultancy; Janssen: Consultancy; Merck: Consultancy; Pfizer: Consultancy, Honoraria, Other: Travel, Accommodation, Expenses, Research Funding; Novartis: Consultancy, Other: travel, accommodation, expenses, Research Funding.

Abstract: Introduction: Bosutinib is approved for patients with Philadelphia chromosome-positive (Ph+) chronic myeloid leukemia (CML) resistant/intolerant to prior therapy and patients with newly diagnosed Ph+ chronic phase (CP) CML. The phase 4 BYOND trial (NCT02228382) further evaluated the efficacy and safety of bosutinib in patients with previously treated CML. We report the final results from BYOND. Methods: Patients with CML resistant/intolerant to previous tyrosine kinase inhibitor therapy received bosutinib 500 mg once daily. This final analysis was based on a November 23, 2020 database lock, after 3 years of follow-up. Results: Of 163 patients who received bosutinib, 156 had Ph+ CP CML; 4 patients with accelerated phase CML and 3 with Ph−/BCR-ABL1+ CML were analyzed separately. At study completion (median follow-up, 47.8 months), 48.1% of patient with Ph+ CP CML were still receiving treatment, and 68.6% completed the study. Most common primary reason for treatment discontinuation was adverse events (AEs) (26.9% [n=42/156]). Median treatment duration was 40.9 months (range, 0.2−50.1) and median dose intensity 306.4 mg/day (range, 79.7−560.6). Dose interruptions due to AEs occurred in 76.3% of patients and dose reductions in 79.5% of patients. Dose reduction (without further reduction) to 400, 300, or 200 mg/day occurred in 35 (22.4%), 46 (29.5%), and 38 (24.4%) patients, respectively. In evaluable patients with Ph+ CP CML, 81.1% (95% CI: 73.7-87.2), 71.8% (95% CI: 63.9-78.9), 59.7% (95% CI: 51.4-67.7) and 48.3% (95% CI: 40.1−56.6) attained or maintained complete cytogenetic response, major molecular response (MMR), MR 4, and MR 4.5 respectively, at any time on treatment. The majority of patients achieved a deeper molecular response relative to baseline while on bosutinib (Table 1). Among responders, the Kaplan-Meier probabilities (95% CI) of maintaining MMR and MR 4 at 36 months were 87.2% (78.0−92.7) and 80.7% (69.4−88.1), respectively. No patients with Ph+ CP CML progressed to accelerated/blast phase on-treatment. At 48 months, the cumulative incidence of progression free-survival events was 5.1% (95% CI: 2.4-9.4) and the Kaplan-Meier overall survival rate 88.3% (95% CI: 81.8-92.6). There were 17 deaths; 2 were considered CML-related (off-treatment progression to AP/BP, n=1; cardiogenic shock, n=1) and none were considered to be treatment-related by the investigator. In the overall patient population (N=163), any grade treatment-emergent AEs (TEAEs) were reported by 99.4% of patients and grade 3/4 TEAEs were reported by 79.1% of patients (Table 2). Most common (≥10%) TEAEs leading to dose reduction were diarrhea (27.0%) and increased ALT (12.3%) and most common TEAEs leading to temporary dose interruption were diarrhea (30.7%), increased ALT (14.7%), vomiting (13.5%), increased AST (11.0%), and nausea (10.4%). AEs leading to treatment discontinuation in ≥2% of patients were increased ALT (4.9%) and AST (2.5%). Conclusions: After 3 years, bosutinib continued to show efficacy in previously treated patients with Ph+ CP CML. Long-term AEs were generally manageable and consistent with previous reports of bosutinib. These results confirm the use of bosutinib as a standard of care in previously treated patients with CML. Figure 1 Figure 1. Disclosures Gambacorti-Passerini: Pfizer: Honoraria, Research Funding; Bristol-Myers Squibb: Consultancy. Brümmendorf: Bristol Myers: Research Funding; Novartis: Honoraria, Patents & Royalties, Research Funding; Janssen: Honoraria; Pfizer: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Repeat Diagnostics: Research Funding; Takepart Media: Honoraria. Abruzzese: Incyte: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Bristol Myers Squibb: Consultancy, Honoraria. Kelly: Takeda: Consultancy; AstraZeneca: Consultancy; Sanofi-Aventis: Consultancy; Denovo Biopharma: Consultancy; Verastem: Consultancy; Amgen: Consultancy; Berkley Lights: Current equity holder in publicly-traded company; Agios: Current equity holder in publicly-traded company; Bayer: Speakers Bureau; Janssen: Speakers Bureau; Novartis: Speakers Bureau; Celgene: Speakers Bureau; Epizyme: Speakers Bureau; Pharmacyclics: Speakers Bureau; Karyopharm: Speakers Bureau; Gilead: Speakers Bureau. Oehler: OncLive: Honoraria; Takeda: Consultancy; Pfizer: Research Funding; BMS: Consultancy. Garcia-Gutiérrez: Bristol-Myers Squibb: Consultancy; Novartis: Consultancy; Incyte: Consultancy; Pfizer: Research Funding. Hjorth-Hansen: Pfizer: Research Funding; Novartis: Research Funding; AOP: Research Funding. Leip: Pfizer: Current Employment, Current equity holder in publicly-traded company. Purcell: Pfizer: Current Employment, Current equity holder in publicly-traded company. Luscan: Pfizer: Current Employment, Current equity holder in publicly-traded company. Viqueira: Pfizer: Current Employment, Current equity holder in publicly-traded company. Giles: Novartis: Consultancy; Actutate Therapeutics: Current Employment; Epigene Therapeutics: Consultancy, Current equity holder in publicly-traded company. Hochhaus: Pfizer: Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol-Myers Squibb: Research Funding; Incyte: Research Funding.