Littérature scientifique sur le sujet « CML, TKI, AOEs, cytokines »

Abstract Background: Tyrosine kinase inhibitors (TKI) may offer a normal life expectancy to Chronic Myeloid Leukemia (CML) patients. However, during treatment with nilotinib, a higher than expected incidence of arterial occlusive events (AOEs) was observed. We retrospectively showed an "inflammatory status" during nilotinib treatment that may explain this increased incidence of AOEs. Here, we report results of a prospective multicenter (KIARO) study including 186 CML patients (89 imatinib, 59 nilotinib, 38 dasatinib) in which pro/anti-inflammatory cytokines were measured at diagnosis and during treatment, with the aim to investigate potential changes in each patient's inflammatory status possibly favoring AOEs. Aims: The aims of this study are: 1) to analyze prospectively inflammation status during TKI treatment; 2) to record AOEs; 3) to calculate the SCORE and evaluate its predictive role for AOEs; 4) to analyze possible associations of AOEs with altered inflammation status. Methods: Inflammatory status was evaluated by measuring IL6, IL10, TNFα, oxLDL and hs-CRP plasma levels at diagnosis and during treatment (+1, +3, +6, +12 months); additionally, clinical and biochemical pro-atherothrombotic profiles and the 10-year SCORE chart were also evaluated. Results: 186 newly-diagnosed CML patients starting either imatinib, nilotinib or dasatinib treatment, entered this study. Regarding the inflammation status, we observed that TNFα and IL6 levels were high at diagnosis and decreased during the first 12 months of treatment regardless the type of TKI; instead, IL10 levels were comparable among the 3 TKI cohorts at baseline, but showed a remarkably different evolution during treatment. In fact, IL10 levels were significantly higher after 6 and 12 months of imatinib (p=0.012 and p=0.009, respectively) and dasatinib (p=0.032 and p=0.014, respectively) compared to nilotinib. Consequently, TNFα/IL10 ratio was significantly higher in nilotinib cohort at 6 and 12 months respect to imatinib (p=0.044 at 6 months and p=0.041 at 12 months) and dasatinib (p=0.040 at 6 months and p=0.044 at 12 months). As well, IL6/IL10 ratio was significantly higher in nilotinib cohort compared to imatinib and dasatinib both at 6 (p=0.042 and p=0.049, respectively) and 12 months (p=0.040 and p=0.041, respectively) (Figure 1). OxLDL levels were similar in the 3 groups for the first 6 months. At 12 months we detected a significant increase of oxLDL levels in the nilotinib cohort (p=0.041), respect to imatinib and dasatinib. We did not find significant differences in hs-CRP levels across the 3 TKIs, although a trend for higher levels was observed in nilotinib cohort. Overall, these results suggest a TKI-driven pro-inflammatory status in nilotinib treated patients. After a median follow-up of 23.3 months of TKI treatment, 10 patients (5.4%) suffered an AOE, specifically: 6 ACS, 2 PAOD, 1 TIA and 1 stroke. 5 events (50%) occurred in patients treated with nilotinib, either in first line (4 patients) or in third line (1 patient, after failure following brief treatment with imatinib and dasatinib). In this subgroup of 10 patients experiencing an AOE, we observed a trend of increased IL6 and TNFα median values both at diagnosis and at each time point, compared with the remaining no-AOE patients. IL10 and oxLDL had similar median concentrations in both AOE and no-AOE cohorts, except for oxLDL at 12 months which resulted higher in patients who experienced AOEs. Moreover, regarding AOEs, nilotinib treatment showed a 3.1 times increased risk compared to other TKIs (HR 3.1, 95% CI 2.6-4.4 p< 0.001), whereas 10-year SCORE was not predictive in the whole cohort (HR 0.6, 95% CI 0.33-0.94 p= 0.094) or in any subgroup (imatinib HR 0.8, 95% CI 0.49-1.03 p= 0.067; nilotinib HR 0.4, 95% CI 0.29-0.76 p= 0.112, dasatinib HR 0.6, 95% CI 0.37-0.92 p= 0.082). Conclusions: Our results showed a pro-inflammatory/oxidative milieu increasing along treatment with nilotinib compared with imatinib or dasatinib, as demonstrated by higher IL6/IL10 and TNFα/IL10 ratios, higher levels of oxLDL and a trend for higher hs-CRP only in nilotinib cohort. However, due to the low number of observed events, a formal statistical analysis for any association between AOEs and pro/anti-inflammatory cytokines levels was not possible. Therefore, a longer follow-up is needed to further confirm the active role of nilotinib in AOEs pathogenesis. Figure 1 Figure 1. Disclosures Abruzzese: Incyte: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Bristol Myers Squibb: Consultancy, Honoraria. Galimberti: Incyte: Speakers Bureau; AbbVie, Janssen: Honoraria, Other: Travel grants. Stagno: Pfizer: Consultancy, Honoraria, Other: Support for attending meetings and/or travel; InCyte: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Other: Support for attending meetings and/or travel, Research Funding.

Abstract INTRODUCTION: Chronic myeloid leukemia (CML) is a bone marrow and blood disorder accounting for 15% of adult leukemia. A shift in CML management has occurred over the past decade with the introduction of tyrosine kinase inhibitors (TKIs), changing CML status from fatal to a chronic, lifelong illness. However, an association between TKI use and cardiovascular events has been observed. This study aimed to compare major adverse cardiac events (MACE), arterial occlusive events (AOEs), and venous thrombotic events (VTEs) among CML patients in chronic phase (CP-CML) treated with different TKIs. METHODS: A retrospective observational study of adult (aged ≥18 years) CP-CML patients prescribed a TKI was conducted using the IBM® MarketScan® Research Databases from July 2012-June 2017. The index date was defined as the index drug prescription date, identified based on TKI use during the identification period (January 2013-December 2016) in hierarchical order: ponatinib, bosutinib without ponatinib, and other TKIs (imatinib, dasatinib, nilotinib) excluding ponatinib and bosutinib. Patients were required to have continuous health plan enrollment for ≥6 months pre-index date (baseline period) and at least 6 months post-index date (follow-up period). Patients with use of one or two previous TKI(s) before the index date were examined separately. Cardiovascular events occurring through the earliest of discontinuation of index TKI, switch to another TKI, or end of follow-up period using ICD-9/10-CM diagnosis codes were calculated as the number of events per 100 person-years. MACE was defined as a composite of stroke (hemorrhagic stroke and ischemic stroke), myocardial infarction, and inpatient death; AOEs included cardiovascular, cerebrovascular, and peripheral vascular events; VTEs included pulmonary embolism and deep vein thrombosis. RESULTS: After applying the selection criteria, 161 patients had one previous use of a TKI, with 50 ponatinib, 80 bosutinib and 31 other TKI patients. Mean ages were 54, 57, and 58 years for ponatinib, bosutinib, and other TKI cohorts, respectively. Most ponatinib patients initiated treatment with a dose of 45 mg (60%); most bosutinib patients initiated with a dose of 500 mg (53%) . For patients with use of one previous TKI, the average Charlson Comorbidity Index score was 1.4 for ponatinib, 1.8 for bosutinib and 0.8 for other TKI patients. Common baseline comorbid conditions by drug included anemia (ponatinib: 50%; bosutinib 31%; other TKI: 19%), hypertension (ponatinib: 32%, bosutinib: 43%, other TKI: 29%), and diabetes (ponatinib: 16%; bosutinib: 28%; other TKI: 10%). CP-CML patients were observed to have cardiovascular events prior to index TKI use, especially MACE (ponatinib: 4%, bosutinib: 16%, other TKI: 3%), and AOEs (ponatinib: 12%; bosutinib: 25%; other TKI: 19%). During the follow-up period, no significant differences were found for cardiovascular events across patients with TKI use (Table 1); the incidence of MACE was 4.7-8.3, AOEs: 25.8-33.3, and VTE: 2.3-9.1 (in 100 person-years). For those with use of two types of TKIs before the index date, 29 ponatinib, 29 bosutinib, and 4 other TKI patients were identified, with an average age of 51, 59, and 65 years, respectively. A similar trend was observed for patients with use of two prior TKIs. CONCLUSION: CP-CML patients treated with different TKIs (ponatinib, bosutinib, imatinib, dasatinib, and nilotinib) did not have different incidence of cardiovascular events (MACE, AOEs, VTEs) in this small cohort of real-world patients with ≥6-month of follow-up. The results were consistent among patients with prior use of one and two TKI types. Disclosures Levy: Takeda (Millennium Pharmaceuticals, Inc.): Consultancy. Xie:STATinMED Research: Employment. Wang:STATinMED Research: Employment. Neumann:Takeda (Millennium Pharmaceuticals, Inc.): Employment. Srivastava:Takeda (Millennium Pharmaceuticals, Inc.): Employment. Naranjo:Takeda (Millennium Pharmaceuticals, Inc.): Employment. Zhang:STATinMED Research: Employment. Dalal:Millennium Pharmaceuticals, Inc., a wholly owned subsidiary of Takeda Pharmaceutical Company Ltd, Cambridge, MA, USA: Employment, Equity Ownership.

7012 Background: The tyrosine kinase inhibitor (TKI) ponatinib has potent activity against native and mutant BCR-ABL1 and is approved for use in pts with relapsed/intolerant CML or Ph+ ALL, or with BCR-ABL1/T315I. Methods: In the pivotal PACE study (NCT01207440), ponatinib (starting dose 45 mg/d) was assessed in pts with CML or Ph+ ALL resistant/intolerant to dasatinib or nilotinib, or with T315I. In Oct ’13, dose reductions were implemented due to observed arterial occlusive events (AOEs). Efficacy and safety at 5 yrs (data as of 3 Oct ’16) for CP-CML pts are reported. Results: Of 270 CP-CML pts in the safety population, 60% received ≥3 prior TKIs. At initiation of study closure, 99 pts were ongoing; among these pts, minimum follow-up was 52 months, and most (78%) had 15 mg/d as their last dose. In all CP-CML pts (n = 267, efficacy evaluable), cumulative response rates were: MCyR, 60%; CCyR, 54%; MMR, 40%; and MR4.5, 24%. Among pts who achieved MCyR (n = 148) or MMR (n = 108), the Kaplan-Meier (KM) estimated probability of remaining in response at 5 yrs was 74% (95% CI, 62 – 83) and 61% (95% CI, 51 – 70), respectively. Regardless of dose reduction in Oct ’13, maintenance of response was high (Table). KM estimated 5-yr rate for PFS/OS was 49%/77%. TEAEs in ≥45% of CP-CML pts were rash 47%, abdominal pain 46%, and thrombocytopenia 46%. Most newly occurring AEs were observed within the first year. The incidence of any AOEs/serious AOEs for CP-CML pts was 29%/23%. Among CP-CML pts with no prior AOEs who had a prospective dose reduction, 17% (11/63) had a first AOE occurring after Oct ‘13. Conclusions: Long-term (5-yr) results from PACE demonstrate that ponatinib continues to show clinical benefit, irrespective of dose reductions, with deep and lasting responses in heavily pretreated CP-CML pts. Safety results were consistent with the safety profile across the ponatinib clinical program. Clinical trial information: NCT01207440. [Table: see text]

INTRODUCTION: Chronic myeloid leukemia (CML) is a bone marrow and blood disorder accounting for 15% of adult leukemia. Tyrosine kinase inhibitors (TKIs) have been the standard of care for CML treatment. However, an association between TKI use and cardiovascular events has been observed. Ponatinib and bosutinib are introduced to provide more options for patients who failed their first-line treatment. The incidence of major adverse cardiac events (MACEs), arterial occlusive events (AOEs), and venous occlusive events (VOEs) were assessed among CML patients who were prescribed ponatinib vs bosutinib. METHODS: A retrospective observational study was conducted among adult CML patients aged ≥18 years with use of 1 or 2 prior TKIs who were prescribed bosutinib or ponatinib. Study patients were selected from the IBM® MarketScan® Research database from July 2012-June 2017. The index date was defined as the index drug prescription date, identified based on TKI use during the identification period (January 2013-December 2016) in a hierarchical order based on the sequence of treatment lines: ponatinib and bosutinib without ponatinib. Continuous health plan enrollment for ≥6 months pre-index date (baseline period) and at least 6 months post-index date (follow-up period) was required. Cardiovascular (CV) events (MACEs, AOEs, VOEs) using ICD-9/10-CM diagnosis codes occurring through the earliest of index TKI discontinuation, switch to another TKI, or end of follow-up period, were calculated as the number of events per 100 person-years (PYs). Inverse probability of treatment weighting (IPTW) was applied to adjust for differences in baseline characteristics between the treatment cohorts. Kaplan-Meier (KM) and Cox proportional hazard model analyses were conducted on the adjusted sample to examine any difference in CV event risk. RESULTS: After applying the selection criteria, 79 and 109 patients were included in the ponatinib and bosutinib cohorts, respectively. Mean ages were 53 years (ponatinib cohort) and 58 years (bosutinib cohort). The average Charlson Comorbidity Index (CCI) scores - defined by categorizing comorbidities using diagnosis codes - were 1.23 for ponatinib and 1.81 for the bosutinib cohort. Common baseline comorbid conditions included anemia (ponatinib: 49%; bosutinib 34%), hypertension (ponatinib: 33%, bosutinib: 46%), and diabetes (ponatinib: 15%; bosutinib: 29%). Some patients were observed to have CV events, specifically MACEs (ponatinib 8%; bosutinib 16%) and AOEs (ponatinib 15%; bosutinib 28%), before index ponatinib or bosutinib use. In the follow-up period, ponatinib patients were associated with a similar incidence of MACEs (14.70 vs 10.46 per 100 PYs; p=0.464), AOEs (29.56 vs 34.50 per 100 PYs; p=0.632), and VOEs (36.21 vs 34.70 per 100 PYs; p=0.890) compared to bosutinib patients. After applying IPTW, similar risks of the CV events (MACE, AOEs, VTEs) were observed in the KM analysis (Figure 1) expressed as time to CV event. After adjusting for additional confounders using Cox models, compared to those with bosutinib use, ponatinib patients were associated with similar rate of MACEs (Hazard Ratio [HR]: 1.02; 95% CI: 0.34, 3.01), AOEs (HR: 0.90; 95% CI: 0.43, 1.85), and VOEs (HR: 0.92; 95% CI: 0.44, 1.94). CONCLUSION: Among CML patients treated with ponatinib or bosutinib in second or third line, similar risks of cardiovascular events (MACE, AOEs, VTEs) were observed in the follow-up in this study in a community setting. Figure 1 Disclosures Levy: Takeda (Millennium Pharmaceuticals): Consultancy. Xie:STATinMED Research: Other: I am a paid employee of STATinMED Research which is a paid consultant to Takeda Pharmaceutical Corporation. . Wang:STATinMED Research: Other: I am a paid employee of STATinMED Research which is a paid consultant to Takeda Pharmaceutical Company. . Neumann:Millennium Pharmaceuticals (Takeda): Employment, Other: I am a paid employee of Millennium Pharmaceuticals, Inc., a wholly owned subsidiary of Takeda Pharmaceutical Company Ltd. Srivastava:Millennium Pharmaceuticals (Takeda): Other: I am a paid employee of Millennium Pharmaceuticals, Inc., a wholly owned subsidiary of Takeda Pharmaceutical Company Ltd. Naranjo:Millennium Pharmaceuticals (Takeda): Other: I am a paid employee of Millennium Pharmaceuticals, Inc., a wholly owned subsidiary of Takeda Pharmaceutical Company Ltd. Xu:Millennium Pharmaceuticals (Takeda): Other: I am a paid employee of Millennium Pharmaceuticals, Inc., a wholly owned subsidiary of Takeda Pharmaceutical Company Ltd. Zhang:STATinMED Research: Other: I am a paid employee of STATinMED Research which is a paid consultant to Takeda Pharmaceutical Corporation.. Dalal:Millennium Pharmaceuticals (Takeda): Other: I am a paid employee of Millennium Pharmaceuticals, Inc., a wholly owned subsidiary of Takeda Pharmaceutical Company Ltd.

7000 Background: PON, a third-generation tyrosine kinase inhibitor (TKI), demonstrated deep and long-lasting responses and survival in patients (pts) with chronic-phase chronic myeloid leukemia (CP-CML) resistant/intolerant to second-generation TKI therapy (PACE; NCT01207440); post hoc analysis suggested a relationship between dose and both adverse events and response. Here we present the primary analysis of OPTIC (NCT02467270), an ongoing, randomized, phase 2 trial with a novel response-based dosing regimen of PON in pts with resistant/intolerant CP-CML. Methods: Pts with CP-CML resistant/intolerant to ≥2 TKIs or with the BCR-ABL1 T315I mutation were randomized to PON starting doses of 45 mg (cohort A; 45 mg → 15 mg), 30 mg (B; 30 mg →15 mg), and 15 mg (C) once daily. Doses were reduced to 15 mg with achievement of ≤1% BCR-ABL1IS in cohorts A and B. The primary endpoint is ≤1% BCR-ABL1IS at 12 mo; secondary endpoints include cytogenetic and molecular responses and safety outcomes. AOEs were adjudicated prospectively by an independent review committee. Results: 283 pts were randomized (A/B/C: n=94/95/94) and had the following baseline characteristics: median age 48 y (18‒81 y); 98% received ≥2 (55% ≥3) TKIs; 99% had resistant disease; 40% had ≥1 baseline mutations (23% T315I). At the primary analysis with 32 mo median follow-up, 134 pts (47%; n=50/41/43) remained on treatment and 204 pts (72%) had PON exposure ≥12 mo. At 12 mo, 44% (41/93) in A, 29% (27/93) in B, and 23% (21/91) in C achieved ≤1% BCR-ABL1IS (Table); primary endpoint was met by cohort A. Dose reductions to 15 mg after achieving response (A/B) were 48/29%. Most common grades ≥3 TEAEs were thrombocytopenia, 27%; neutropenia, 17%; and anemia, 7%. AOEs/serious AOEs were reported in cohorts A (10%/4%), B (5%/4%), and C (3%/3%). Dose reductions or discontinuations for TEAEs (A/B/C) were 46/35/32% and 19/16/14%, respectively. Conclusions: The OPTIC primary analysis demonstrates the optimal benefit:risk profile for PON was achieved with a response-based dosing regimen starting with 45 mg/d, followed by dose reduction to 15 mg/d upon achieving ≤ 1% BCR-ABL1IS; 30 mg→15 mg and 15 mg cohorts may provide benefit, especially in pts without T315I mutation (Table). The observed ≤1% BCR-ABL1IS responses are supported by robust survival outcomes in pts with CP-CML resistant to second-generation BCR-ABL1 TKI therapy, both with and without BCR-ABL1 mutations. Clinical trial information: NCT02467270. [Table: see text]

Abstract Background . Arterial occlusive events (AOEs) represent emerging complications in chronic myeloid leukemia (CML) patients treated with ponatinib, with a cumulative incidence correlated with the higher dose of the drug and longer treatment duration. Current recommendations highlight the importance of a careful evaluation of cardiovascular (CV) risk factors at baseline.Moreover, a preventive strategy with primary prophylaxis based on aspirin still remains under discussion and no data have been reported on secondary prophylaxis. Methods. We investigated a consecutive series of adult CML patients (mean age 50 years, range 24-81) who initiated ponatinib, between January 2012 and December 2016 at 15 Italian centers. Patients were stratified according to the Systematic Coronary Risk Evaluation (SCORE) assessment, based on gender, age, smoking habits, systolic blood pressure, and total cholesterol levels. Additional risk factors were considered the presence of diabetes, body mass index > 24.5 kg/m2, mild or severe renal insufficiency, and dyslipidemia. CML patients were also evaluated for both comorbidities and a positive anamnesis of CV diseases.Primary and secondary CV prophylaxis before starting ponatinib was also reported. We evaluated the cumulative incidence of AOEs (myocardial infarction, angina, ischemic cerebrovascular events and peripheral vascular disease) after initiating treatment with ponatinib, and their management. Results. A total of 71 patients were retrospectively identified. The reasons for treatment with ponatinib were inefficacy of previous tyrosine kinase inhibitors (TKIs) in 80.2% and intolerance in 19.8%. The median time of exposure to ponatinib was 16 months (range 3-69).The 60-month cumulative incidence of AOEs was 30.9±11.5%.Patients aged ≥60 years showed a higher incidence of AOEs (61.8±19.5% vs 19.5±12.0%, p=0.001) (Figure 1). The majority of patients (95%) were classified as at low-intermediate SCORE risk and 5% as at high-very high SCORE risk. Patients with a high-very high SCORE showed a significantly higher incidence of AOEs (100% vs. 25.8±11.5%; p<0.002). In multivariate analysis, no association was found with positive anamnesis of CV diseases, CV risk factors, dose of ponatinib (15, 30, 45 mg), exposure time to ponatinib, and number of TKI treatments; only age ≥60 years showed a significative association (p=0.016) . Overall, 13 patients underwent aspirin 100 mg primary prophylaxis before starting ponatinib and showed a a lower albeit not statistically significant incidence of AOEs (14.3±13.2% vs 33.4±12.8%, p=NS). In 6 of these patients with age < 60 years, no AOEs was reported. Conversely, the cumulative incidence of AOEs in the 6 patients undergoing secondary prophylaxis (anticoagulant, cardioaspirin) for previous events was 100% at 30 months. Overall, 23 CV AEs were registered; 52.1% of CV AEs were graded as 3/4 according to common toxicity criteria. In 43.4% of cases, ponatinib treatment did not require dose modification, 34.8% of patients reduced the dose and 21.8% discontinued the treatment. The majority of patients required additional diagnostic tests as ECG/cardiac ultrasound, peripheral vascular Doppler or cranial/CT; 4 patients underwent a coronarography procedure and 1 patient required invasive procedures as percutaneous transluminal angioplasty and application of coronary stents. Finally, the 5-year cumulative incidence of MR4 following ponatinib treatment was 45.0±12.3% and it was not influenced significantly by AOEs occurrence. Conclusions. This study confirms the increased risk of AOEs in CML patients treated with ponatinib in the real-life, particularly in patients aged ≥60 years. Our findings emphasize the need of personalized prevention strategies based on CV risk factors, in close collaboration with cardio-oncologists, angiologists and vascular surgeons. We suggest that patients treated with ponatinib should undergo prophylaxis with aspirin 100 mg. Data on the efficacy of primary prophylaxis need to be confirmed in larger cohorts of patients and in prospective randomised trials. Figure 1.Arterial Occlusive Events (AOEs) cumulative incidence according to age ≥ 60 years in 71 CML patients treated with ponatinib Figure. Figure. Disclosures Abruzzese: BMS: Consultancy; Novartis: Consultancy; Ariad: Consultancy; Pfizer: Consultancy. Bonifacio:Incyte: Consultancy; Pfizer: Consultancy; Amgen: Consultancy; Novartis: Research Funding; Bristol Myers Squibb: Consultancy. Foà:CELTRION: Other: ADVISORY BOARD; GILEAD: Speakers Bureau; ABBVIE: Other: ADVISORY BOARD, Speakers Bureau; CELGENE: Other: ADVISORY BOARD, Speakers Bureau; NOVARTIS: Speakers Bureau; ROCHE: Other: ADVISORY BOARD, Speakers Bureau; INCYTE: Other: ADVISORY BOARD; AMGEN: Other: ADVISORY BOARD; JANSSEN: Other: ADVISORY BOARD, Speakers Bureau. Breccia:Incyte: Honoraria; BMS: Honoraria; Novartis: Honoraria; Pfizer: Honoraria.

Abstract Background Tyrosine kinase inhibitors (TKIs) currently represent the main therapy for chronic myeloblastic leukemia (CML). Although they are therapeutically effective, some TKI-related events such as pleural effusion and elevation of large granular lymphocytes (LGL) have been reported. In addition, these events itself may affect the therapeutic response to TKIs. In the present study, we measured the levels of some cytokines, chemokines, soluble factors and coagulation markers in patients with CML, and investigated the relationship between these markers and TKI-related events. Methods The subjects were 48 patients with CML. Blood samples were collected and levels of cytokines (interleukin (IL)-6, tumor necrosis factor-α, high-mobility group box 1), chemokines (monocyte chemotactic protein (MCP)-1, RANTES), soluble molecules (soluble vascular cell adhesion molecule-1, soluble E-selectin, angiopoietin-2, vascular endothelial growth factor, and soluble thrombomodulin) and coagulation markers (plasminogen activator inhibitor (PAI)-1, platelet-derived microparticles (PDMP)) were measured by ELISA. Results Levels of all markers except IL-6 and MCP-1 were significantly increased in patients with de novo CML. Level of LGL/lymphocyte was significantly higher in dasatinib-treated CML patients compared to other TKI-treated patients. LGL/lymphocyte and many biomarkers exhibit the time-dependent increase after dasatinib treatment. In addition, LGL/lymphocyte was already increasing in patients with pleural effusion before dasatinib treatment. Conclusion These results suggest that LGL and endothelial-cell-related factors play an important role in the pathophysiology of CML and its response to TKIs. Disclosures: No relevant conflicts of interest to declare.

Abstract Abstract 857 Tyrosine kinase inhibitors (TKI) like imatinib and dasatinib are the current treatment of choice for patients with chronic myeloid leukemia (CML). Although most patients enter a complete remission during treatment, cure of the disease is usually not achieved since recurrence of the disease is seen in the majority of patients upon discontinuation of the treatment, indicating that the leukemic stem cell is not efficiently targeted. Furthermore, in accelerated phase and blast crisis of CML TKI treatment only results in temporary control of the disease. In these situations allogeneic stem cell transplantation (allo-SCT) and application of donor T cells may be the only curative treatment. Besides the direct anti-leukemic effect of allo-SCT, alloreactive T cells recognizing CML (progenitor) cells, and the formation of immunological memory may lead to effective lifelong immune surveillance. Therefore, we investigated whether the leukemic cells persisting during TKI treatment are susceptible targets for the anti-leukemic effect mediated by donor T cells after allo-SCT and whether continuous TKI treatment may have an additive effect during the immunological intervention. To investigate the anti-leukemic effect of the two strategies, CD34+ positive CML cells were isolated from bone marrow, and labeled with the fluorescent dyes CFSE or PKH to allow monitoring of single cell proliferation. CML cells were exposed to imatinib (1-100μM) or dasatinib (0.01-50nM), and/or to CD8+ alloreactive cytotoxic T lymphocyte (CTL) clones in the presence of proliferation-inducing cytokines. The number, phenotype, and proliferative status of the CML cells persisting after single and combined interventions were measured by quantitative flowcytometric analysis. In the absence of therapeutic interventions the majority of CD34+ CML cells entered proliferation. However, a small population of CD34+ CML stem cells residing in the non-dividing peak could be identified despite the addition of cytokines. Addition of imatinib or dasatinib resulted in efficient dose-dependent induction of cell death of the leukemic cells (99% lysis by 25μM imatinib or 10nM dasatinib). However, the population of quiescent CD34+ CML stem cells was not affected. Moreover, the number of cells present in the non-dividing population increased 2-fold compared to the non-treated controls at the highest TKI concentrations, indicating additional growth arrest of a population of proliferating CML precursor cells. We next tested the capacity of different HLA-A2-restricted CD8+ CTL clones to kill non-treated or imatinib or dasatinib treated CML cells. Whereas the proliferating CD34+ CML precursors were efficiently lysed, the population of quiescent stem cells was capable of withstanding CTL exposure. Detailed phenotypic analysis revealed significant downregulation of HLA-A2 and the adhesion molecules CD49d and CD58 on these quiescent cells, probably resulting in the impaired ability of these target cells to form a high avidity interaction with the T cells. The increased population of non-dividing cells as a result of the TKI pretreatment showed similar resistance to T cell induced cell death, indicating that TKI treatment may even diminish the anti-leukemic effect of allo-SCT. In the absence of therapeutic control, as mimicked by the removal of T cells and TKI from the cultures, outgrowth of the leukemic cells re-occurred, illustrating their capacity to give rise to a relapse of the disease. Next, we analyzed the effect of TKI treatment on T cell survival and functionality. Whereas resting primary T cells were insensitive to TKI treatment, T cells activated by either polyclonal stimulation with anti-CD3/CD28 beads or stimulation with allogeneic stimulator cells died after TKI exposure at similar concentrations as the leukemic cells. In conclusion, TKI treatment results in selection of a population of quiescent leukemic stem cells showing cross-resistance to CTL-induced cell death, most likely due to their inability to form a high avidity interaction. Moreover, T cells actively participating in the anti-leukemic immune response after allo-SCT are suppressed by TKI. These data indicate that continuous TKI treatment may potentially hamper the curative effect of allo-SCT. Disclosures: No relevant conflicts of interest to declare.

TPS7073 Background: Ponatinib is an oral TKI with potent activity against BCR-ABL1. The pivotal PACE study (NCT01207440) formed the basis for approval of ponatinib in the US for the treatment of patients with resistant/intolerant CML or Ph+ ALL, or those with the T315I mutation. Long-term follow-up of PACE showed a higher cumulative incidence of vascular occlusive events (VOEs) than reported at the time of approval — dose reductions were later implemented to mitigate VOEs. VOEs comprise arterial occlusive events (AOE) and venous thromboembolic events. The exposure-adjusted incidence of AOEs has not increased over time in PACE; in patients with a history of ischemic disease, the relative risk of serious AOEs was 2.6 in those with ≥2 vs 0 risk factors. The primary objective of this patient registry is to assess VOEs occurring during ponatinib use in routine clinical practice in the US. Methods: OMNI (NCT02455024) is a prospective observational registry of eligible patients (Table) with CML or Ph+ ALL for whom the decision to initiate treatment with ponatinib has already been made for the approved US indications. Patients voluntarily enroll into the registry, which is non-interventional with no protocol-mandated tests/procedures — all treatment decisions are made at the discretion of the health care practitioner in consultation with their patient. Study duration is anticipated as ~30 mo (~18-mo enrollment followed by 12 mo of data collection, which will occur every 3 mo). The primary analysis will be performed 12 mo after last patient enrolled and will estimate the incidence of VOEs by duration of ponatinib exposure. To understand differences between those with and without VOEs, exploratory analyses will be performed, considering factors such as patient demographics, risk factors for developing VOEs, dose and duration of ponatinib treatment, and concomitant medications. VOE outcomes also will be assessed. Enrollment will begin in 2017, with a target of ≥300 patients. Clinical trial information: NCT02455024. [Table: see text]

Abstract Chronic myelogenous leukemia (CML) is maintained by a minor population of leukemic stem cells (LSCs) that exhibit innate resistance to tyrosine kinase inhibitors (TKIs) targeting BCR-ABL. Innate resistance can be induced by cytokines and growth factors secreted by bone marrow stromal cells (BMSFs) that protect CML-LSCs from TKIs, resulting in minimal residual disease. Developing therapies that can be combined with TKIs to eradicate TKI-insensitive CML-LSCs, is critical for disrupting innate TKI resistance and preventing disease relapse. Cancer cells balance reactive oxygen species (ROS) and antioxidants at higher than normal levels, which promotes their proliferation and survival, but also makes them susceptible to damage by ROS-generating agents. BCR-ABL expression increases cellular ROS levels, whereas, TKI inhibition of BCR–ABL reduces ROS. Furthermore, BMSFs, which are implicated in innate TKI resistance, can increase ROS levels in CML cells. Thus, we postulated that BMSF mediated increases in ROS might enhance triggering of ROS-mediated damage in TKI treated CML-LSCs by chaetocin, a mycotoxin with anticancer properties that imposes oxidative stress by inhibiting thioredoxin reductase-1. To investigate chaetocin effects on innate TKI resistance, we first compared its activity with imatinib against TonB210, a murine hematopoietic cell line with inducible BCR-ABL expression, in response to BMSFs. Imatinib did not affect the growth of BCR-ABL(-) TonB210 cells but suppressed BCR-ABL(+) Ton-B210 growth, and BMSFs protected against imatinib growth suppression. In contrast, chaetocin significantly suppressed the growth of both BCR-ABL(-) and BCR-ABL(+) TonB210 cells, and these effects were potentiated by BMSFs. We then compared the effects of chaetocin as a single agent, and in combination with imatinib, on the growth of CML-LSCs derived from an established murine retroviral transduction/transplantation model of CML blast crisis, in response to BMSFs. The presence of BMSFs reduced cytotoxicity and apoptosis induction by imatinib, but potentiated these effects in chaetocin treated CML-LSCs. Colony formation by CML-LSCs was significantly inhibited by treatment with either imatinib or chaetocin. However, BMSFs conferred significant protection from colony inhibition by imatinib, whereas, no colony formation was observed in cells exposed to chaetocin and BMSFs. Both BMSFs and chaetocin increased ROS in CML-LSCs and the addition of BMSFs and chaetocin resulted in significantly higher levels compared to chaetocin or BMSFs alone. Pretreatment of CML-LSCs with the anti-oxidant N-acetyl-cysteine blocked chaetocin cytotoxicity, even in the presence of BMSFs. Chaetocin effects on CML-LSC self-renewal in vivo were assessed by transplanting CML-LSCs into secondary recipients following in vitro exposure to chaetocin, in the presence or absence of BMSFs. Disease latency in mice transplanted with CML-LSCs following chaetocin treatment more than doubled compared to mice transplanted with untreated CML-LSCs or CML-LSCs exposed to BMSFs. Mice transplanted with CML-LSCs following chaetocin treatment in the presence of BMSFs had significantly extended survival time compared to mice transplanted with CML-LSCs treated with chaetocin alone. Our findings indicate that chaetocin activity against leukemia initiating cells is significantly enhanced in the presence of BMSFs and suggest that chaetocin may be effective as a co-drug to complement TKIs in CML treatment by disrupting the innate resistance of CML-LSCs through an ROS dependent mechanism. Disclosures No relevant conflicts of interest to declare.

Chronic myeloid leukemia (CML) treatment with tyrosine kinase inhibitors (TKIs) has been associated to an increased risk of Arterial Occlusive Events (AOEs), mainly with nilotinib, but the mechanisms underlying these events have been not clarified yet. Previously, we confirmed in our retrospective cross-sectional study a higher cardiovascular (CV) risk in nilotinib treated patients, particularly if harboring the unfavorable OLR1 polymorphism and we found a nilotinib-associated pro-inflammatory effect. We started a multicenter prospective study of tyrosine Kinase Inhibitors induced pro-AtherothROmbotic (KIARO) status in CML patients to furtherly investigate a possible pro-atherothrombotic nilotinib-induced status in a cohort of chronic phase (CP)-CML patients treated with first-line imatinib, nilotinib and dasatinib. In particular, our intents were: to assess any changes in the inflammation status during TKI treatment by measuring pro/anti-inflammatory cytokines (IL-6, IL-10, TNFα and ox-LDL) plasma levels; 2) to record AOEs after applying CV SCORE and evaluate its predictive role; 3) to correlate AOEs with altered inflammation status. A total of 186 CP-CML patients were enrolled in this study of which 89/186 (48%) were treated with imatinib, 59/186 (32%) with nilotinib and 38/186 (20%) with dasatinib. Results from biochemical analyses performed by enzyme-linked immunosorbent assay (ELISA) test showed higher IL-10 levels at 6 and 12 months in imatinib (p=0.012 and p=0.009, respectively) and dasatinib (p=0.032 and p=0.014, respectively) cohorts compared to nilotinib, while ox-LDL levels increased at 12 months in the nilotinib cohort (p=0.041) in contrast to imatinib and dasatinib. Consequently, IL-6/IL-10 and TNFα/IL-10 ratios were higher in nilotinib cohort compared to imatinib (p=0.042, p=0.044 at 6 months; p=0.040, p=0.041 at 12 months) and dasatinib (p=0.049, p=0.040 at 6 months; p=0.041, p=0.044 at 12 months), suggesting a TKI-driven pro-inflammatory status in nilotinib treated patients. We recorded an AOE only in 5% of patients and, due to the small number of events detected, it was not possible to establish a correlation between AOEs and pro/anti-inflammatory cytokine levels. Although we applied the SCORE chart in all CML patients enrolled to better identify patients with high risk to experience AOEs, this parameter was not predictive for our cohort. This result may be explained by the strategic choice of TKI at diagnosis, as documented also by the lower median age of the nilotinib treated patients compared to the other two TKI subgroups and by the higher number of traditional CV risk factors in imatinib cohort respect to nilotinib and dasatinib. Considering that our results showed a pro-inflammatory status in nilotinib subgroup during the first year of treatment and that AOEs occurred after a median treatment duration of 19,1 months, we believe that a further evaluation of pro/anti-inflammatory cytokines at longer treatment follow-up should be performed to better investigate the correlation between pro-atherothrombotic status and AOEs. In conclusion, we suggest a careful selection of the TKI treatment, according to the presence of baseline CV risk factors and/or previous CV history, in order to offer the best and safe long-term TKI treatment for CML patients, considering as ultimate goal the possibility of reaching a safe TFR and reducing AOEs associated comorbidities.