ALBERT

Description: In Ph+ ALL, the absence of detectable disease has shown prognostic value for a reduced risk of relapse and improved survival. However, as the level of undetectable disease is determined by the lower limit of detection of the test in use, standardization of such an endpoint for a drug regulatory submission is critical. To date, no tyrosine kinase inhibitor (TKI) has received approval for the newly diagnosed Ph+ ALL adult patient population in the US. Takeda (Millennium Pharmaceuticals, Inc.) is conducting a phase 3, randomized, open-label, multicenter efficacy study comparing ponatinib versus imatinib, administered in combination with reduced-intensity chemotherapy, in participants with newly diagnosed Ph+ ALL (NCT03589326). The primary endpoint for this study is minimal residual disease (MRD)-negative complete remission (CR), where MRD-negativity is defined as a BCR-ABL:ABL raw ratio of ≤0.01% (MR4.0) in bone marrow aspirate samples at the end of induction. Patients who achieve post-induction ponatinib or imatinib maintained MRD-negative CR will potentially delay or avoid stem cell transplantation. Previously, for the purposes of initiating and monitoring treatment free remission or discontinuation of TKI therapy in chronic phase CML patients, we developed and validated the MRDx® BCR-ABL Test which is an FDA authorized test for the quantitative detection of BCR-ABL e13a2 or e14a2 transcripts. This test will be used in this study and reports BCR-ABL:ABL levels on the International Scale (IS) with traceability to the World Health Organization (WHO) first International Genetic Reference Panel and with a limit of detection below 0.0032% (i.e., MR4.5). Similarily, for assessment of the e1a2 (p190) BCR-ABL:ABL transcripts, we developed and validated a one-step reverse transcription, quantitative polymerase chain reaction (RT-qPCR) test in order to accurately and precisely assess all clinical decision points and disease levels for this study. Because of the lack of available reference material for e1a2, a droplet digital PCR (ddPCR) based test was co-developed to quantify e1a2 BCR-ABL copy numbers in bone marrow aspirates, as well as in peripheral blood samples (to allow assessment of concordance). e1a2 in vitro transcribed RNA calibrators assign copy numbers to determine the e1a2 BCR-ABL:ABL raw % ratios of unknown samples. The e1a2 RT-qPCR test exceeded an analytical sensitivity of MR4.5 (0.0032% raw ratio of BCR-ABL:ABL) with a dynamic linear range from MR4.5 to MR1.0. The test also includes cell line derived RNA assay controls formulated to 10%, 0.1% and 0.01% BCR-ABL:ABL, necessary for decision points in the clinical trial. Validation studies included limit of blank, limit of detection (LOD), limit of quantification, assay range, analytical specificity, repeatability, reproducibility (multi-day, multi-operator, and multi-instrument), and accuracy by comparison to a reference method (ddPCR). The validation of the e1a2 RT-qPCR test with bone marrow aspirate samples was conducted with 1 µg RNA inputs per well and LOD was also verified with 0.5 µg RNA input per well. In conclusion, the validated e1a2 RT-qPCR test allows for accurate standardization of BCR-ABL:ABL measurement across multiple centers in an international Phase 3 study. The e1a2 RT-qPCR test data will be used to assess the primary endpoint in the first registrational trial to be conducted in newly diagnosed Ph+ ALL adult patients. Disclosures Drafahl: MolecularMD, Corp: Employment. Smith:MolecularMD, Corp: Employment. Graham:MolecularMD, Corp: Employment. Glynn:MolecularMD, Corp: Employment. Spittle:MolecularMD, Corp: Employment. Verrow:Takeda (Millennium Pharmaceuticals, Inc.): Employment. Rivera:Takeda (Millennium Pharmaceuticals, Inc.): Consultancy. Srivastava:Takeda (Millennium Pharmaceuticals, Inc.): Employment. Hawkins:MolecularMD, Corp: Employment. Galderisi:MolecularMD, Corp: Employment, Equity Ownership.

Description: 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.

Description: 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.

Description: Introduction: The use of 2G TKIs in patients with CP-CML who have failed ≥1 2G TKIs is not associated with durable responses; there is limited clinical evidence to support that switching to alternate 2G TKI therapy improves long-term clinical outcomes for these patients. Patients with resistant and intolerant CP-CML with substantial prior 2G treatment demonstrated deep, lasting responses to PON in the pivotal PACE trial. A post hoc modeling analysis of the data from PACE suggested a relationship between dose and safety events (including arterial occlusive events [AOEs]). The OPTIC trial was designed to prospectively evaluate response-based PON dosing regimens with the aim of optimizing its efficacy and safety in patients with CP-CML; the interim analysis (IA) demonstrated clinically manageable safety and AOE profiles with response-based PON dosing regimens. The combined PACE and OPTIC trials comprise the largest patient population in a post-2G TKI setting. We present the efficacy and safety outcomes of these patients over time. Methods: PACE (NCT01207440) evaluated PON in patients with refractory CML or Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukemia (ALL). OPTIC (NCT02467270) is a multicenter, randomized Phase 2 trial characterizing the safety and efficacy of PON over a range of 3 starting doses (45, 30, or 15 mg/day); patients with CP-CML receiving 45 or 30 mg/day reduced their doses to 15 mg/day upon achieving ≤1% BCR-ABL1IS. Data from patients with CP-CML in PACE (n=254) and the 45-mg starting dose cohort (45 mg→15 mg) in OPTIC (n=92) who have been treated with ≥1 2G TKI are presented; OPTIC data are from the IA. Efficacy data includes molecular responses (measured using polymerase chain reaction and performed at the same central lab for both studies) and survival outcomes over time. Safety data, including treatment-emergent AOE rates following adjudication, are also presented. Results: A combined 350 PON-treated patients from the PACE and OPTIC trials who have received ≥1 prior 2G TKI were analyzed; efficacy results are summarized in Table 1. The ≤1% BCR-ABL1IS response rates increased over time and ranged from 42% to 52% in the OPTIC IA 45-mg starting dose cohort and in PACE. Progression-free survival and overall survival were 52% and 73%, respectively, in PACE (up to 5 years) and 81% and 93%, respectively, at the OPTIC IA (up to 2 years) (Table 1). Serious treatment-emergent adverse event (AE) and AOE rates (including exposure-adjusted AOE rates) were lower in OPTIC IA with a response-adjusted dosing regimen compared with PACE (Table 2). Propensity score analyses comparing AOE incidence among all patients in OPTIC vs PACE demonstrate that the relative risk for adjudicated AOEs is 64% lower in OPTIC when compared with PACE after adjusting for baseline differences, duration of exposure, and total PON dose received. Analyses on responses by mutation status also will be presented. Conclusions: In this analysis, comprising the largest patient population of CP-CML patients in a post-2G TKI setting, ponatinib shows high response rates and robust survival outcomes in patients who have failed 2G TKIs. With the response-adjusted dosing regimen in OPTIC (starting at 45 mg and reducing to 15 mg upon response), efficacy outcomes were consistent with that of PACE, while the overall incidences of AOEs and serious treatment emergent-AEs were lower; exposure-adjusted AOEs during the first 2 years were also lower. The ongoing OPTIC study is also evaluating lower starting doses of ponatinib (30 and 15 mg) and primary analysis of this study will provide a refined understanding of the benefit:risk profile of the 3 starting doses of ponatinib in CP-CML patients. Disclosures Kantarjian: Adaptive biotechnologies: Honoraria; Ascentage: Research Funding; Actinium: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria; Pfizer: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Sanofi: Research Funding; Immunogen: Research Funding; BMS: Research Funding; Daiichi-Sankyo: Honoraria, Research Funding; Aptitute Health: Honoraria; BioAscend: Honoraria; Delta Fly: Honoraria; Amgen: Honoraria, Research Funding; Abbvie: Honoraria, Research Funding; Oxford Biomedical: Honoraria; Jazz: Research Funding. Deininger:Fusion Pharma: Consultancy; Blueprint Medicines Corporation: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: part of a study management committee, Research Funding; SPARC: Research Funding; DisperSol: Consultancy; Leukemia & Lymphoma Society: Research Funding; Novartis: Consultancy, Other, Research Funding; Medscape: Consultancy; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol-Myers Squibb: Consultancy, Honoraria, Other, Research Funding; Galena: Consultancy, Honoraria, Other; Pfizer: Honoraria, Other, Research Funding; Ariad: Consultancy, Honoraria, Other; Celgene: Research Funding; Gilead Sciences: Research Funding; Sangamo: Consultancy, Membership on an entity's Board of Directors or advisory committees; Incyte: Consultancy, Honoraria, Other, Research Funding. Abruzzese:Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Incyte: Consultancy, Membership on an entity's Board of Directors or advisory committees; Bms: Honoraria. Apperley:Pfizer: Honoraria, Research Funding, Speakers Bureau; Novartis: Honoraria, Speakers Bureau; Incyte: Honoraria, Research Funding, Speakers Bureau; Bristol Myers Squibb: Honoraria, Speakers Bureau. Cortes:Pfizer: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Takeda: Consultancy, Research Funding; Jazz Pharmaceuticals: Consultancy, Research Funding; Sun Pharma: Research Funding; BiolineRx: Consultancy, Research Funding; Amphivena Therapeutics: Research Funding; Telios: Research Funding; BioPath Holdings: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol-Myers Squibb: Research Funding; Astellas: Research Funding; Daiichi Sankyo: Consultancy, Research Funding; Merus: Research Funding; Immunogen: Research Funding; Arog: Research Funding. Chuah:Pfizer: Other: Travel, Research Funding; Korea Otsuka Pharmaceutical: Honoraria; Bristol-Myers Squibb: Honoraria, Research Funding; Novartis: Honoraria. DeAngelo:Jazz: Consultancy; Autolos: Consultancy; Novartis: Consultancy, Research Funding; Abbvie: Research Funding; Forty-Seven: Consultancy; Amgen: Consultancy; Agios: Consultancy; Blueprint Medicines Corporation: Consultancy, Research Funding; Takeda: Consultancy; Glycomimetics: Research Funding; Pfizer: Consultancy; Shire: Consultancy; Incyte Corporation: Consultancy. DiPersio:Magenta Therapeutics: Membership on an entity's Board of Directors or advisory committees. Hochhaus:Bristol-Myers Squibb: Honoraria, Research Funding; Incyte: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding; Takeda: Honoraria; MSD: Research Funding. Lipton:Takeda: Consultancy, Honoraria, Research Funding; Ariad: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Bristol-Myers Squibb: Honoraria; BMS: Consultancy, Research Funding; Pfizer: Consultancy, Honoraria, Research Funding. Nicolini:Sun Pharma Ltd: Consultancy; Incyte: Research Funding, Speakers Bureau; Novartis: Research Funding, Speakers Bureau. Pinilla Ibarz:Takeda: Consultancy, Speakers Bureau; Sanofi: Consultancy; TG Therapeutics: Consultancy; Sunesis Pharmaceuticals: Consultancy; Abbvie: Consultancy, Speakers Bureau; Janssen: Consultancy, Speakers Bureau; Novartis: Consultancy; Pharmacyclics: Consultancy, Speakers Bureau; AstraZeneca: Consultancy, Speakers Bureau. Rea:BMS: Membership on an entity's Board of Directors or advisory committees; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Incyte: Honoraria, Membership on an entity's Board of Directors or advisory committees. Rosti:Pfizer: Research Funding, Speakers Bureau; Bristol-Myers Squibb: Speakers Bureau; Incyte: Speakers Bureau; Novartis: Speakers Bureau. Rousselot:Pfizer: Consultancy, Research Funding; Incyte: Consultancy, Research Funding; Takeda: Consultancy; Bristol-Myers Squibb: Consultancy; Novartis: Consultancy. Shah:Bristol-Myers Squibb: Research Funding. Talpaz:IMAGO: Consultancy; BMS: Membership on an entity's Board of Directors or advisory committees; Takeda: Research Funding; Novartis: Research Funding; Constellation Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees. Srivastava:Takeda: Current Employment. Lu:Millennium Pharmaceuticals, Inc., a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Current Employment. Mauro:Bristol-Myers Squibb: Consultancy, Honoraria, Other: Travel, Accommodation, Expenses, Research Funding; Pfizer: Consultancy, Honoraria, Other: Travel, Accommodation, Expenses, Research Funding; Sun Pharma/SPARC: Research Funding; Takeda: Consultancy, Honoraria, Other: Travel, Accommodation, Expenses, Research Funding; Novartis: Consultancy, Honoraria, Other: Travel, Accommodation, Expenses, Research Funding.

Description: Introduction: In PACE (NCT01207440), patients with refractory chronic-phase chronic myeloid leukemia (CP-CML) with substantial prior second-generation tyrosine kinase inhibitor (TKI) treatment demonstrated deep, lasting responses to ponatinib. However, long-term follow-up identified rates of arterial occlusive events (AOEs) as a risk. OPTIC (NCT02467270) is a randomized Phase 2 trial evaluating ponatinib at 3 starting doses: 45 mg, 30 mg, and 15 mg daily in patients with CP-CML resistant/intolerant to ≥2 TKIs or with a T315I mutation. The interim analysis showed that the 45-mg (vs 30 mg or 15 mg) starting dose (with reduction to 15 mg upon response) provided the best clinical outcomes and responses were maintained in 〉75% of patients who dose reduced. Here, we present efficacy and safety outcomes by baseline mutation status and line of treatment for the 3 dose cohorts. Methods: Patients with CP-CML resistant/intolerant to ≥2 TKIs or with T315I mutation were randomized to ponatinib starting doses of 45 mg (Cohort A; 45 mg → 15 mg), 30 mg (B; 30 mg → 15 mg), and 15 mg (C) once daily (qd). Doses were reduced to 15 mg on achievement of ≤1% BCR-ABL1ISin Cohorts A and B. Doses also could be reduced for safety. The primary endpoint is ≤1% BCR-ABL1IS at 12 months. In this analysis, the outcome was analyzed by baseline mutation status (none, any, T315I, and non-T315I) and number of prior TKIs (≤2 or ≥3) in the intent-to-treat (ITT) population. Treatment-emergent adverse events (TEAEs), serious TEAEs, and AOEs by adjudication were summarized by number of prior TKIs (≤2 or ≥3). Interim analysis results are descriptive. Results: Patients (N=283) were randomized: A/B/C n=94/95/94; median age was 48 y (18‒81 y). Seven patients were excluded from the intent-to-treat population (N=276) because they had atypical transcripts. Mutation status was well balanced between cohorts; 59% had no mutation, 41% had ≥1 baseline mutation, 24% had T315I, and 17% had a non-T315I mutation. In all categories of mutation status, the rate of ≤1% BCR-ABL1IS by 12 months was highest in Cohort A, with the most notable differences seen in patients with T315I (A: 60%, B: 25%, C: 6%) (Table 1). Patients with no mutations or other mutations had smaller differences but the outcomes all still favored 45 mg. Patients in all cohorts were treated with multiple TKIs, with 54% (A), 60% (B), and 53% (C) having 3 or more prior TKIs. The rate of ≤1% BCR-ABL1IS by 12 months was highest in Cohort A, both in patients treated with ≤2 or ≥3 prior TKIs (43% and 49%, respectively) (Table 1). Table 2 shows rates of TEAEs and TE-AOEs by cohort and number or prior TKIs. There was a trend toward higher event rates in Cohort A and for patients treated with ≥3 TKIs. Rates of adjudicated AOEs were low (≤6%) in all 3 cohorts irrespective of the number of prior TKIs. Conclusions: At this interim analysis with a median follow-up of ~21 months, the maximum benefit:risk, regardless of mutation status or number of prior TKIs, was observed in patients treated with a 45-mg starting dose, with a reduction to 15 mg upon achievement of response. Patients with the T315I mutation who initiated ponatinib at 45 mg experienced better response rates than those who initiated ponatinib at 30-mg or 15-mg starting doses. Primary analysis will provide a refined understanding of the benefit:risk profile of 3 different starting doses of ponatinib. Disclosures Cortes: BioPath Holdings: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Sun Pharma: Research Funding; Telios: Research Funding; Amphivena Therapeutics: Research Funding; Astellas: Research Funding; Bristol-Myers Squibb: Research Funding; BiolineRx: Consultancy, Research Funding; Arog: Research Funding; Jazz Pharmaceuticals: Consultancy, Research Funding; Daiichi Sankyo: Consultancy, Research Funding; Immunogen: Research Funding; Merus: Research Funding. Apperley:Bristol Myers Squibb: Honoraria, Speakers Bureau; Incyte: Honoraria, Research Funding, Speakers Bureau; Novartis: Honoraria, Speakers Bureau; Pfizer: Honoraria, Research Funding, Speakers Bureau. Hochhaus:Novartis: Honoraria, Research Funding; Incyte: Honoraria, Research Funding; Bristol-Myers Squibb: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding; Takeda: Honoraria; MSD: Research Funding. Mauro:Sun Pharma/SPARC: Research Funding; Pfizer: Consultancy, Honoraria, Other: Travel, Accommodation, Expenses, Research Funding; Takeda: Consultancy, Honoraria, Other: Travel, Accommodation, Expenses, Research Funding; Novartis: Consultancy, Honoraria, Other: Travel, Accommodation, Expenses, Research Funding; Bristol-Myers Squibb: Consultancy, Honoraria, Other: Travel, Accommodation, Expenses, Research Funding. Rousselot:Bristol-Myers Squibb: Consultancy; Pfizer: Consultancy, Research Funding; Novartis: Consultancy; Takeda: Consultancy; Incyte: Consultancy, Research Funding. Sacha:Incyte: Consultancy, Honoraria, Speakers Bureau; Bristol-Myers Squibb Company: Consultancy, Honoraria, Speakers Bureau; Adamed: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Speakers Bureau; Pfizer: Consultancy, Honoraria, Speakers Bureau. Talpaz:Novartis: Research Funding; IMAGO: Consultancy; Constellation Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; BMS: Membership on an entity's Board of Directors or advisory committees; Takeda: Research Funding. Chuah:Korea Otsuka Pharmaceutical: Honoraria; Pfizer: Other: Travel, Research Funding; Novartis: Honoraria; Bristol-Myers Squibb: Honoraria, Research Funding. Lipton:Bristol-Myers Squibb: Honoraria; Pfizer: Consultancy, Honoraria, Research Funding; BMS: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Ariad: Consultancy, Research Funding; Takeda: Consultancy, Honoraria, Research Funding. Deininger:SPARC: Research Funding; Novartis: Consultancy, Other, Research Funding; Sangamo: Consultancy, Membership on an entity's Board of Directors or advisory committees; Incyte: Consultancy, Honoraria, Other, Research Funding; Blueprint Medicines Corporation: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: part of a study management committee, Research Funding; Fusion Pharma: Consultancy; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Medscape: Consultancy; DisperSol: Consultancy; Leukemia & Lymphoma Society: Research Funding; Gilead Sciences: Research Funding; Ariad: Consultancy, Honoraria, Other; Bristol-Myers Squibb: Consultancy, Honoraria, Other, Research Funding; Galena: Consultancy, Honoraria, Other; Celgene: Research Funding; Pfizer: Honoraria, Other, Research Funding. Schiffer:BMS: Consultancy; Novartis: Consultancy; Takeda: Research Funding. García Gutiérrez:Pfizer: Honoraria, Other: travel/accommodations/expenses, Research Funding; Novartis Pharma AG: Consultancy, Honoraria, Other: travel/accommodations/expenses, Research Funding; Incyte: Consultancy, Honoraria, Other: travel/accommodations/expenses, Research Funding. de Lavallade:Novartis: Honoraria; Pfizer: Honoraria; BMS: Honoraria, Research Funding; Incyte: Honoraria, Research Funding. Etienne:Bristol-Myers Squibb: Consultancy, Research Funding, Speakers Bureau; Novartis: Consultancy, Research Funding, Speakers Bureau; Pfizer: Consultancy, Speakers Bureau; Incyte: Consultancy, Speakers Bureau. Lu:Millennium Pharmaceuticals, Inc., a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Current Employment. Srivastava:Takeda: Current Employment. Rosti:Novartis: Speakers Bureau; Incyte: Speakers Bureau; Bristol-Myers Squibb: Speakers Bureau; Pfizer: Research Funding, Speakers Bureau.