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Ponatinib, the only third-generation pan-BCR::ABL1 inhibitor with activity against all known BCR::ABL1 mutations including T315I, has demonstrated deep and durable responses in patients with chronic-phase chronic myeloid leukemia (CP-CML) resistant to prior second-generation (2G) TKI treatment. We present efficacy and safety outcomes from the Ponatinib Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL) and CML Evaluation (PACE) and Optimizing Ponatinib Treatment in CP-CML (OPTIC) trials for this patient population. PACE (NCT01207440) evaluated ponatinib 45 mg/day in CML patients with resistance to prior TKI or T315I. In OPTIC (NCT02467270), patients with CP-CML and resistance to ≥2 prior TKIs or T315I receiving 45 or 30 mg/day reduced their doses to 15 mg/day upon achieving ≤1% BCR::ABL1

The BCR-ABL1 inhibitor ponatinib is approved for the treatment of adults with chronic myeloid leukemia or Philadelphia chromosome-positive acute lymphoblastic leukemia, including those with the T315I mutation. We report a population pharmacokinetic (PK) model-based analysis for ponatinib and its application to inform dose selection for pediatric development. Plasma concentration-time data were collected from 260 participants (86 healthy volunteers; 174 patients with hematologic malignancies) enrolled across 7 clinical trials. Data were analyzed using nonlinear mixed-effects modelling. Ponatinib PK was described by a 2-compartment model with first-order elimination from the central compartment. The final model included body weight and age as covariates on the apparent central volume of distribution; however, exposure variability explained by these covariates was small compared with overall variability in the population. None of the covariates evaluated, including sex, age (19-85 years), race, body weight (40.7-152.0 kg), total bilirubin (0.1-3.16 mg/dL), alanine aminotransferase (6-188 U/L), albumin (23.0-52.5 g/L), and creatinine clearance (≥28 mL/min) had clinically meaningful effects on apparent oral clearance. Simulations based on the final model predicted that daily doses of 15-45 mg result in steady-state average concentrations that are in the pharmacological range for BCR-ABL1 inhibition and approximate or exceed concentrations associated with suppression of T315I mutant clones. The final model was adapted using allometric scaling to inform dose selection for pediatric development. Clinicaltrials.gov identifier NCT00660920; NCT01667133; NCT01650805 This article is protected by copyright. All rights reserved.

Introduction SHP656 is the first factor VIII (FVIII) product developed using polysialylation (PSA) technology, in which full‐length recombinant (r) FVIII (anti‐haemophilic factor [recombinant]) is conjugated with a 20 kDa PSA polymer. Aim To compare the safety, immunogenicity and pharmacokinetics of SHP656 vs the parent rFVIII (octocog alfa) after single infusions of 25‐75 IU/kg in patients with severe haemophilia A (FVIII activity

TPS9158 Background: In cancer, the accumulation of adenosine in the tumor microenvironment (TME) mediates immune suppression mainly via the high affinity A2A receptor (A2AR), causing dysregulation of innate and adaptative immune cell subsets and dampening the antitumor immune response. This results in increased tumor cell survival and immune escape (Blay 1997; Merighi 2003; Muller-Haegele 2014). Therefore, inhibiting A2AR could reverse immunosuppression and re-establish immune surveillance in the tumor microenvironment. Inupadenant is an antagonist of the A2AR with potent inhibition of A2AR even at the high concentrations of adenosine present in the tumor microenvironment. Ongoing clinical studies have established inupadenant as a molecule with a favorable safety profile with preliminary evidence of clinical activity in multiple tumor types, including durable PRs in patients who have exhausted standard treatment options (Buisseret 2021). The standard treatment for patients without a driving mutation who progress on first-line IO is a platinum-based doublet chemotherapy regimen. Carboplatin plus Pemetrexed (C+P) is the preferred chemotherapy in nonsquamous mNSCLC. Study A2A-005 will evaluate the efficacy of inupadenant in combination with C+P as a second-line therapy in adult patients with nonsquamous mNSCLC (post-IO). A successful outcome from study A2A-005 will help address a high unmet need for this patient population and could lead to new therapeutic options. Methods: This is a 2-part study. The first part is an open label dose-finding part to determine the safety and recommended Phase 2 dose (RP2D) of inupadenant in combination with C+P (N = 40). In Part 2, 150 patients will be randomized 1:1 to inupadenant or placebo, both in combination with C+P. Tumor response will be determined according to RECIST 1.1 criteria and safety findings will be reviewed by the Safety Review Committee (for Part 1) and the Data Monitoring Committee (for Part 2). Key eligibility criteria include 1) mNSCLC of nonsquamous pathology, 2) have received only 1 line of anti-PD-(L)1 therapy in the metastatic setting, without concomitant chemotherapy, and have progressed (IO/IO combination therapy is allowed), 3) have measurable disease as defined by RECIST v1.1 criteria and 4) Eastern Cooperative Oncology Group status ≤1. Primary endpoints are RP2D (for Part 1) and PFS (for Part 2). Secondary endpoints include change in tumor size, ORR, OS, and adverse events. Correlative aims include assessing blood and tissue biomarkers for association with clinical benefit. The study will be conducted in approximately 11 countries in North America and Europe. Clinical trial information: EudraCT 2021-005487-22.

Introduction In this real-world study, the incidence of cardiovascular events (CV) including major adverse cardiac events (MACE), arterial occlusive events (AOE), and venous occlusive events (VOE) was evaluated in chronic myeloid leukemia (CML) patients treated with ponatinib or bosutinib in a US commercial database population. Materials and Methods CML patients aged ≥18 years with use of 1 or 2 prior tyrosine kinase inhibitors prescribed bosutinib or ponatinib were selected from the IBM® MarketScan® Research database. Cox proportional hazard model analyses were conducted to examine any difference in CV event risk. Results Ponatinib and bosutinib was associated with similar incidence and risk of CV events, including MACEs (HR: 1.02; 95% CI: 0.35, 3.01), AOEs (HR: 0.90; 95% CI: 0.43, 1.85) and VOEs (HR: 0.92; 95% CI: 0.44, 1.94). Conclusion Treatment with ponatinib or bosutinib was not associated with significant differences in the incidence of CV events in CML patients.

In PACE (Ponatinib Ph+ ALL and CML Evaluation), a phase 2 trial of ponatinib that included patients with chronic-phase chronic myeloid leukemia (CP-CML) resistant to multiple prior tyrosine kinase inhibitors (TKIs), ponatinib showed deep and durable responses, but arterial occlusive events (AOEs) emerged as notable adverse events. Post hoc analyses indicated that AOEs are dose dependent. We assessed the benefit/risk ratio across 3 ponatinib starting doses in the first prospective study to evaluate a novel, response-based, dose-reduction strategy for TKI treatment. Adults with CP-CML resistant to or intolerant of at least 2 prior BCR-ABL1 TKIs or with a BCR-ABL1 T315I mutation were randomly assigned 1:1:1 to 3 cohorts receiving ponatinib 45, 30, or 15 mg once daily. In patients who received 45 or 30 mg daily the dose was reduced to 15 mg upon response (BCR-ABL1IS transcript levels ≤1%). The primary end point was response at 12 months. From August 2015 through May 2019, 283 patients were randomly assigned to the cohorts: 282 (94 per dose group) received treatment (data cutoff, 31 May 2020). The primary end point (98.3% confidence interval) was achieved in 44.1% (31.7-57.0) in the 45-mg cohort, 29.0% (18.4-41.6) in the 30-mg cohort, and 23.1% (13.4-35.3) in the 15-mg cohort. Independently confirmed grade 3 or above treatment-emergent AOEs occurred in 5, 5, and 3 patients in the 45-, 30-, and 15-mg cohorts, respectively. All cohorts showed benefit in this highly resistant CP-CML population. Optimal benefit/risk outcomes occurred with the 45-mg starting dose, which was decreased to 15 mg upon achievement of a response. This trial is registered on www.clinicaltrials.gov as NCT02467270.

Context: PON, a third-generation tyrosine kinase inhibitor (TKI), demonstrated deep, long-lasting responses/survival in patients 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 adverse events/response. We present the primary analysis of OPTIC (NCT02467270), an ongoing, randomized, phase 2 trial in resistant/intolerant CP-CML to evaluate safety and efficacy of PON response–based dosing regimens. Methods: Patients 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), 30 mg (B), and 15 mg (C) once daily. Doses were reduced to 15 mg with achievement of ≤1% BCR-ABL1IS in cohorts A and B. Primary endpoint is Results: 283 patients 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 32-mo median follow-up, 134 patients (47%; n=50/41/43) remained on treatment and 204 patients (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; cohort A met the primary endpoint. Progression-free survival/overall survival at 36 months was 73/89% (A), 66/89% (B), and 70/92% (C). Most common grade ≥3 treatment-emergent adverse events (TEAEs) were thrombocytopenia, 27%; neutropenia, 17%; and anemia, 7%. Arterial occlusive events (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. Observed ≤1% BCR-ABL1IS responses are supported by robust survival outcomes in patients with and without BCR-ABL1 mutations. The OPTIC study is sponsored by ARIAD Pharmaceuticals, Inc., a wholly owned subsidiary of Takeda Pharmaceutical Company Limited, with additional funding from Incyte Corporation (Wilmington, DE).

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.

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.

Objectives In the PACE trial 5-year analysis evaluating use of ponatinib in patients with refractory chronic myeloid leukemia (CML) and Ph+ acute lymphoblastic leukemia, a 25% incidence of AOEs was identified (Cortes, Blood 2018) using Medical Dictionary for Regulatory Activities (MedDRA) preferred terms (PTs). We performed a retrospective review using a charter-based independent Adjudication Committee (AC) to better understand clinically relevant AOE rates in PACE. Methods The AC (3 cardiologists, 1 hematologist, and 1 neurologist) evaluated AOEs (identified using >500 terms) in PACE using established definitions developed by the American College of Cardiology/American Heart Association (ACC/AHA), US Food and Drug Administration (FDA), and Standardized Data Collection for Cardiovascular Trials Initiative (SCTI). The AC also reviewed patient profiles including event, severity, concomitant medication, and hospitalization data. These adjudicated results were compared with pre-adjudication MedDRA PT search results. The AC was blind to dose, dose modification, and investigator causality opinion. Events not associated with a cardiovascular etiology or that failed to meet the ACC/AHA, FDA, and SCTI definitions were determined by the AC not to be AOEs. Results This review included all 449 heavily pretreated patients with Ph+ leukemia enrolled in PACE (median age, 59 y; 47% female; 93% ≥2 tyrosine kinase inhibitors). At a median follow-up of 37.3 months, adjudicated AOEs occurred in 17.4% of the overall patient population compared with 24.7% pre-adjudication. The majority of the pre-adjudication serious AOEs were adjudicated as serious AOEs (20% pre-adjudication vs 16% adjudicated). The most common adjudicated AOE (>2%) was peripheral arterial occlusive disease. Exposure-adjusted incidence of newly occurring adjudicated AOEs decreased over time. Analyses by baseline risk factors demonstrated that patients with the following baseline risk factors had higher incidence rates of adjudicated AOEs than those without ischemic cardiac disease, hypertension, hypercholesterolemia, and diabetes. Conclusions Independent AC review of the PACE trial identified a lower rate of clinically relevant AOEs than previously reported, suggesting an earlier possible overestimation that may not accurately reflect the risk of AOEs with ponatinib. The ongoing ponatinib dose-ranging OPTIC study will further evaluate dose-dependent AOE incidence rates.

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]

Objectives In PACE ( NCT01207440 ), heavily pretreated patients with chronic-phase chronic myeloid leukemia (CP-CML) demonstrated deep, lasting ponatinib responses; long-term follow-up showed increasing rates of arterial occlusive events (AOEs). We present OPTIC ( NCT02467270 ) interim analysis (IA) results, evaluating the association between ponatinib exposure, efficacy, and safety. Methods This phase 2 trial randomized patients with CP-CML resistant/intolerant to ≥2 tyrosine kinase inhibitors (TKIs) or with a T315I mutation to ponatinib starting doses of 45 mg (cohort A), 30 mg (B), and 15 mg (C) qd. Doses were reduced to 15 mg qd on achievement of ≤1% BCR-ABL1IS in A/B. Primary endpoint: 12-month ≤1% BCR-ABL1IS; secondary endpoints include cytogenetic and molecular response, and AOE, venous thromboembolism (VTE), and treatment-emergent adverse event rates. IA results are descriptive and will be inferential by adjusting multiplicity across 3 cohorts at final analysis. Results 283 patients were randomized (A/B/C: n=94/95/94); median age 48 y (range, 18-81 y). 26% had hypertension history; 2/43/55% received 1/2/ ≥3 TKIs; 40% had ≥1 baseline mutations, with 23% T315I, all well balanced between cohorts. At IA data cutoff (20 Jul 2019), 162 patients (57%; n=57/51/54) remained on treatment. Within the safety population (N=282), median duration of exposure was ∼1 y (A/B/C, 14/12/12 mo). At 12 mo, 39% (95% CI, 27.6, 50.6), 27% (17.6, 39.1), and 26% (16.5, 38.6) in A, B, and C, respectively, achieved ≤1% BCR-ABL1IS. Dose reductions due to efficacy (A/B): 35/21%. Molecular responses were maintained in all patients who were on the reduced dose for at least 90 days (n=37). Most common TEAEs (any grade/≥3): thrombocytopenia 39/27%, neutropenia 25/17%. AOEs/serious AOEs were reported by (A, B, C) in 5%/2%, 4%/3%, and 1%/0%. Dose reductions for TEAEs: (A/B/C): 44/31/28%; discontinuations due to TEAEs: 18/15/14%. There were 4 (1.4%) on-study deaths; A, sudden death, n=2; C, pneumonia, n=2; no deaths were due to AOEs. Conclusions OPTIC IA shows a trend toward dose-dependent efficacy and safety, and may provide a refined understanding of the ponatinib benefit:risk profile and its relation to dose. Data from longer follow-up may support an alternate dosing regimen for patients with CP-CML.

7502 Background: In PACE (NCT01207440) heavily pretreated patients (pts) with chronic-phase CML (CP-CML) had deep, lasting responses to PON; long-term follow-up showed increasing rates of arterial occlusive events (AOEs). We present IA results from OPTIC (NCT02467270), evaluating the association between PON exposure, efficacy, and safety, and response-based dose reduction in pts with CP-CML. Methods: This ongoing, multicenter, randomized phase 2 trial enrolled pts with CP-CML resistant or intolerant to ≥2 TKIs or with a T315I mutation to receive PON at a starting dose of 45 mg (cohort A), 30 mg (B), and 15 mg (C) qd. Doses were reduced to 15 mg qd on achievement of ≤1% BCR-ABL1IS in A/B. Primary endpoint: 12 mo ≤1% BCR-ABL1IS; secondary endpoints include cytogenetic and molecular response and AOE, VTE, and TEAE rates. Results are descriptive at this IA and will be inferential by adjusting multiplicity across 3 cohorts at final analysis. Results: 283 pts were randomized (A/B/C: n = 94/95/94); median age 48 y (18‒81 y). 26% had hypertension history; 2/43/55% received 1/2/≥3 TKIs; 40% had ≥1 baseline (BL) mutations, with 23% T315I. At IA data cutoff (20 Jul 2019), 162 pts (57%; n = 57/51/54) remained on study treatment. Among 282 pts in the safety population, median duration of exposure was ≈1 y (A/B/C, 12.9/11.2/11.0 mo). At 12 mo, 39% (95% CI, 27.6, 50.6), 27% (17.6, 39.1), and 26% (16.5, 38.6) in A, B, and C, respectively, achieved ≤1% BCR-ABL1IS. Additional efficacy in Table. Dose reductions due to efficacy (A/B): 35/21%. Most common TEAEs (any grade/≥3): thrombocytopenia 39/27%, neutropenia 25/17%. AOEs/serious AOEs were reported by (A, B, C) 5%/2%, 4%/3%, and 1%/0%. Dose reductions due to TEAEs: (A/B/C): 44/31/28%; discontinuations due to TEAEs: 18/15/14%. There were 4 (1.4%) on-study deaths; A, sudden death, n = 2; C, pneumonia, n = 2; no deaths were due to AOEs. Clinical trial information: NCT01207440 . Conclusions: OPTIC IA shows a trend toward dose-dependent efficacy and safety and may provide a refined understanding of the PON benefit:risk profile and its relation to dose. Data from longer follow-up may support an alternate dosing regimen for pts with CP-CML. [Table: see text]

7550 Background: The final 5-year analysis of the PACE trial, which evaluated use of PON in pts with refractory chronic myeloid leukemia (CML) and Ph+ acute lymphoblastic leukemia, identified a 25% incidence of AOEs (Cortes, Blood 2018) from a search utilizing > 400 preferred terms (PTs) defined by MedDRA and related to vascular ischemia or thrombosis. We performed a retrospective review using an independent Endpoint Adjudication Committee (EAC) to better understand clinically relevant AOE rates in PACE. Methods: The EAC consisted of 3 cardiologists, 1 hematologist, and 1 neurologist to review AOEs (identified using > 500 terms) in PACE using American College of Cardiology/American Heart Association (ACC/AHA) definitions for major adverse cardiovascular events (MACE), and to review pt profiles including event, severity, concomitant medication, and hospitalization data. These results were compared with MedDRA PT search results. The EAC was blind to dose, dose modification, and investigator causality opinion. Results: The PACE review included 449 heavily pretreated pts with Ph+ leukemia (median age, 59 y; 47% female; 93% ≥2 tyrosine kinase inhibitors). With median follow-up 37.3 mo in all pts, AOEs were identified by MedDRA PT search in 25% of pts and EAC-verified in 17% (Table). In each category listed in the table, the EAC verification identified fewer AOEs and serious AOEs. Serious AOEs were identified by MedDRA PT search in 20% of pts and EAC-verified in 16%. Events that were not associated with a cardiovascular etiology or failed to meet the MACE definition set forth by the ACC/AHA were determined by the EAC not to be an AOE. Conclusions: The independent EAC review showed a lower rate of clinically relevant AOEs than was reported in PACE, suggesting an earlier possible overestimation that may not accurately reflect the risk of AOEs with PON. The ongoing PON dose-ranging OPTIC study will further evaluate the PON risk:benefit profile. 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.

TPS7061 Background: Therapies for adults with newly diagnosed Ph+ ALL are limited and associated with poor outcomes. PON, a potent TKI, is active against native BCR-ABL1 and all identified single resistance mutations, including T315I, which confers resistance to other TKIs (Zhou. Chem Biol Drug Des 2011;77). In the phase 2 PACE study, PON had a 41% major hematologic response rate in heavily pretreated Ph+ ALL, but responses were not durable mainly due to compound mutations (Cortes. Blood 2018;132; Pritchard. Blood 2016;128). As PON suppresses single BCR-ABL1 resistance mutations, resistance in Ph+ ALL is acquired through compound mutations. Decreased likelihood of compound mutations with first-line PON in Ph+ ALL may lead to more durable responses compared with PON in later lines of therapy. In a phase 2 study of PON with CT in newly diagnosed Ph+ ALL, long-term outcomes were improved vs first/second-generation TKIs (Jabbour. Lancet Haematol 2018;5). The PhALLCON trial compares first-line PON vs IM with reduced-intensity CT. Methods: This open-label trial (NCT03589326) is enrolling 230–320 pts (≥18 y) with newly diagnosed Ph+ or BCR-ABL1–positive ALL (p190/p210) and ECOG status ≤2. Pts are randomized 2:1 to PON 30 mg/d or IM 600 mg/d PO with reduced-intensity CT in induction (cycles [C] 1-3), consolidation (C4-9), and maintenance (C10-20). PON dose is reduced to 15 mg once pt achieves minimal residual disease–negative (MRD−) complete remission (CR). After 20C, pts stay on single-agent PON/IM. CNS prophylaxis: 2x/mo in C1-6. Primary endpoint: MRD− (BCR-ABL/ABL1 ≤0.01%) CR (end of induction). Key secondary endpoint: EFS; others in the Table. Subgroup analysis: pts with/without HSCT. Exploratory endpoints include mutation status. Initiated Aug 2018; to include ~110 sites in ≤35 countries. Currently, 5 active sites (4 US, 1 Spain); accrual ongoing. Clinical trial information: NCT03589326. [Table: see text]

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.

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.

The 5-HT3 1 receptor is a member of the Cys-loop superfamily of ligand-gated ion channels (LGICs) and mediates excitatory fast synaptic transmission in the central and peripheral nervous systems (1). Presynaptic localized 5-HT3 receptors modulate the release of several neurotransmitters, including acetylcholine, dopamine, and γ-aminobutyric acid (2, 3) . In common with all members of the Cys-loop family of LGICs, 5-HT3 receptors are assembled as a pentamer of subunits that surround, in a pseudosymetric manner, a cation-selective ion channel (4–6). Of the five subunits (A–E) cloned to date, only the 5-HT3A and 5-HT3B subunits have been demonstrated to have functional significance in the central or peripheral nervous system (1, 7–9). The 5-HT3A subunit is able to assemble as a homomeric pentamer and is the predominant form of the 5-HT3 receptors present in the rodent brain (10). In contrast, the other 5-HT3R subunits (B–E) must coassemble with the 5-HT3A subunit to form functional receptors (9). The 5-HT3A subunit, along with all Cys-loop LGIC subunits, share a common structural architecture that is comprised of a large extracellular N-terminal domain, four transmembrane domains/α-helices (M1–M4), connected by extracellular (M2–M3) and intracellular (M1–M2 and M3–M4) loops, and an extracellular C-terminus (11–12). The five M2 helices are arranged about a central axis orthogonal to the membrane forming the channel lumen, and the M1, M3, and M4 helices form an outer ring that shields M2 from the lipid bilayer. Due to the abundance and purity of muscle-type nicotinic acetylcholine receptors (nAChRs) in preparations from the electric organ of the Torpedo electric ray, it is the most studied and understood member of the Cys-loop LGIC superfamily, and many of the structural/functional features of the Torpedo nAChR may be generalized to other member of the Cys-loop superfamily. The 5-HT3A subunit shares about 22–30% sequence identity/homology with Torpedo AChR subunits (1, 13) and a variety of studies utilizing different methodologies, including the construction of functional α7AChR/5-HT3AR chimeras, have contributed to the consensus view that the Torpedo AChR, the 5-HT3AR and other Cys-loop LGIC members display a common three-dimensional architecture (11–14). Nevertheless, direct structural information regarding the 5-HT3AR is currently lacking. This is in large part due to the low expression level of 5-HT3ARs (

Nicotinic acetylcholine receptor (nAChR) agonists, such as epibatidine and its molecular derivatives, are potential therapeutic agents for a variety of neurological disorders. In order to identify determinants for subtype-selective agonist binding, it is important to determine whether an agonist binds in a common orientation in different nAChR subtypes. To compare the mode of binding of epibatidine in a muscle and a neuronal nAChR, we photolabeled Torpedo alpha(2)betagammadelta and expressed human alpha4beta2 nAChRs with [(3)H]epibatidine and identified by Edman degradation the photolabeled amino acids. Irradiation at 254 nm resulted in photolabeling of alphaTyr(198) in agonist binding site Segment C of the principal (+) face in both alpha subunits and of gammaLeu(109) and gammaTyr(117) in Segment E of the complementary (-) face, with no labeling detected in the delta subunit. For affinity-purified alpha4beta2 nAChRs, [(3)H]epibatidine photolabeled alpha4Tyr(195) (equivalent to Torpedo alphaTyr(190)) in Segment C as well as beta2Val(111) and beta2Ser(113) in Segment E (equivalent to Torpedo gammaLeu(109) and gammaTyr(111), respectively). Consideration of the location of the photolabeled amino acids in homology models of the nAChRs based upon the acetylcholine-binding protein structure and the results of ligand docking simulations suggests that epibatidine binds in a single preferred orientation within the alpha-gamma transmitter binding site, whereas it binds in two distinct orientations in the alpha4beta2 nAChR.

Neuronal nAChR subtype-selective agonists have potential therapeutic uses in many neurological disorders. Determination of structural aspects unique to individual nAChR agonist binding sites (ABS) is important to the development of nAChR subtype-selective agonists/ligands. To this end, we photolabeled Torpedo, α4β2 and α4β4 nAChRs with [3H]Epibatidine. [3H]Epibatidine binds to α4β2 and α4β4 nAChRs with high affinity (10-200 pM) and binds with similar affinity at the α1-γ and α1-δ ABS of the Torpedo nAChR (∼11 nM). At the subunit level, [3H]Epibatidine photoincorporated into the principal component of the ABS (α1 and α4 subunits) and the complementary component of the ABS in γ and β4 subunits but not in the δ or β2 subunits. Since little is known about the photochemistry of [3H]Epibatidine and the stability of UV-induced [3H]Epibatidine-amino acid adducts under Edman degradation conditions, we first established the merit of [3H]Epibatidine as a photoaffinity probe by determining sites of [3H]Epibatidine labeling in the Torpedo nAChR. The principal sites of labeling were αTyr198 within Loop C and γLeu109 and γTyr117 within Loop E of ABS (see figure). Studies are currently underway to identify the sites of labeling within the α4 and β4 subunits.View Large Image | View Hi-Res Image | Download PowerPoint Slide

The development of nicotinic acetylcholine receptor (nAChR) agonists, particularly those that discriminate between neuronal nAChR subtypes, holds promise as potential therapeutic agents for many neurological diseases and disorders. To this end, we photoaffinity labeled human alpha4beta2 and rat alpha4beta4 nAChRs affinity-purified from stably transfected HEK-293 cells, with the agonists [(125)I]epibatidine and 5[(125)I]A-85380. Our results show that both agonists photoincorporated into the beta4 subunit with little or no labeling of the beta2 and alpha4 subunits respectively. [(125)I]epibatidine labeling in the beta4 subunit was mapped to two overlapping proteolytic fragments that begin at beta4V102 and contain Loop E (beta4I109-P120) of the agonist binding site. We were unable to identify labeled amino acid(s) in Loop E by protein sequencing, but we were able to demonstrate that beta4Q117 in Loop E is the principal site of [(125)I]epibatidine labeling. This was accomplished by substituting residues in the beta2 subunit with the beta4 homologs and finding [(125)I]epibatidine labeling in beta4 and beta2F119Q subunits with little, if any, labeling in alpha4, beta2, or beta2S113R subunits. Finally, functional studies established that the beta2F119/beta4Q117 position is an important determinant of the receptor subtype-selectivity of the agonist 5I-A-85380, affecting both binding affinity and channel activation.