ALBERT

Description: Introduction: Exportin-1 (XPO1), a nuclear transport protein critical for the export of tumor suppressor proteins (TSPs) and select mRNAs to the cytoplasm, is highly expressed in acute myeloid leukemia (AML) and correlates with poor survival. Selinexor, an oral, first-in-class, selective inhibitor of nuclear export, blocks XPO1 function. We previously reported that sequential treatment of AML blasts using the hypomethylating agent decitabine followed by selinexor exhibited strong anti-leukemic effects in vivo by inducing the expression of silenced TSPs that are kept in the nucleus by XPO1 inhibition (Ranganathan, Blood 2015). Methods: Based on these findings, a phase I dose-escalation study was initiated to evaluate the safety, feasibility, maximum tolerated dose (MTD), recommended phase 2 dose (RP2D), and preliminary clinical activity of selinexor in combination with decitabine in poor-risk AML pts (NCT02093403). Adults with relapsed or refractory (R/R) AML and older (age ≥60) unfit pts with untreated AML were eligible. Pts received 10-day decitabine induction(s) at 20mg/m2 on days 1-10 for up to four 28-day cycles in combination with selinexor once daily, twice weekly beginning on day 11. Pts with

Description: Monitoring BCR-ABL transcript levels in patients on TKI therapy using real-time quantitative PCR is standard of care in the management of CML, and achieving sensitivity to 4.5 logs below baseline is important in patients being considered for TKI discontinuation. In order to accurately assess treatment response, it is essential to ensure that variability in testing methodologies is tightly controlled. This has resulted in substantial efforts to standardize BCR-ABL molecular measurement across laboratories by introducing an International Scale (IS). Here we describe the development and analytical evaluation of Xpert® BCR-ABL Ultra, an automated cartridge-based BCR-ABL monitoring assay incorporating lot-specific standardization to the International Scale as defined by WHO. The BCR-ABL Ultra cartridge simplifies the generation of highly accurate and reproducible assay results by integrating nucleic acid extraction, target amplification, and quantification of the BCR-ABL b3a2 or b2a2 transcripts relative to ABL in peripheral blood specimens. The assay turn-around-time is approximately 2.5 hours and has a %BCR-ABL/ABL(IS) dynamic range of ~6 logs, including two key milestones for the assessment of clinical response at ~10% (IS) (SD=~0.08Log) and ~0.0033% (IS) (SD=~0.25Log) (CMR4.5). Lot-to-lot standardization is achieved using a secondary standard panel of controls derived from and aligned to the first WHO international genetic reference panel. The secondary standards are produced at Cepheid as part of the assay kit manufacturing process and applied to every production lot of cartridges in order to improve assay reliability and reporting comparability. Analytical sensitivity studies using spiked-in CML cell lines demonstrated a limit of detection (LoD) and limit of quantification (LoQ) of 0.003% BCR-ABL/ABL (IS) with a limit of blank (LoB) of 0.00017%. In an analytical specificity study, assay results were negative in 100% of 70 known CML-negative samples, including 20 AML or ALL patients and 50 healthy donors. A study was further conducted to estimate the lower limit of clinical sensitivity using blood from 12 CML patients on TKI therapy who had achieved and maintained MMR with reporting below 0.05% (IS). Eleven out of twelve low CML subjects were detected in at least 19 out of 20 replicates tested per subject over a range of 0.038% (SD=~0.17Log) to 0.0011% (IS) (SD=~0.4Log). In conclusion, the Xpert BCR-ABL Ultra assay demonstrates sensitivity in the range necessary to make clinical decisions regarding the continuation of TKI therapy in patients achieving CMR4.5, and every production lot of cartridges is assigned a unique conversion factor guaranteeing alignment to the WHO International Scale. Disclosures Uy: Novartis: Research Funding.

Description: Background:Spleen tyrosine kinase (SYK) is a nonreceptor cytoplasmic tyrosine kinase primarily expressed in cells of hematopoietic lineage. Constitutive activation of SYK in acute myeloid leukemia (AML) has been reported and targeted inhibition of SYK induced differentiation in vitro and demonstrated anti-leukemia activity in AML mouse models. SYK has also been shown to directly phosphorylate the FLT3 receptor, modulating its activation and possibly promoting its role in leukemogenesis. Entospletinib is an orally bioavailable, selective inhibitor of SYK shown to be clinically active in B-cell malignancies. Here we evaluate the combination of entospletinib in patients with untreated AML using a 14-day window phase to assess single-agent activity, then adding standard intensive chemotherapy. Methods: In this phase 1b/2 study (NCT02343939), patients age 18 to 70 years with previously untreated AML, preserved organ function, and ECOG ≤ 2 were eligible to receive dose escalated entospletinib for 14 days as monotherapy (days -14 to 0) followed by combination with daunorubicin 60 mg/m2/d, cycle 1 day 1 to 3, and cytarabine 100 mg/m2/d, cycle 1 day 1 to 7. All patients received entospletinib monotherapy for up to 14 days prior to starting induction. Chemotherapy could be initiated after 5 days of monotherapy (and entospletinib continued for 4+ weeks) in patients with leukemia-related complications necessitating chemotherapy. Patients enrolled to dose level (DL) 0 and DL 1 received entospletinib 200 mg po BID and 400 mg po BID, respectively. Patients with residual disease two weeks after chemotherapy received a second induction cycle identical to the first. Entospletinib was continued without interruption until remission was assessed at count recovery. Results:Twelve patients enrolled with a median age of 54 (range, 18-69) years. Patients were in the following European LeukemiaNet genetic risk groups: favorable (n=1), intermediate I (n=3), intermediate II (n=2), and adverse (n=4), respectively. Three patients were not evaluable for dose limiting toxicity (DLT) assessment and were replaced (due to detection of CNS disease requiring non-study therapy (n=1), and withdrawal of consent unrelated to drug toxicity (n=2)). Single-agent entospletinib during the window period was well tolerated; toxicities after combination with intensive chemotherapy were common and typical. Among 3 patients treated at 200mg BID, no DLT was observed. Of 3 patients treated at 400mg BID, a patient with documented fungal pneumonia developed grade 3 pneumonitis that was possibly related to entospletinib. Although this did not meet DLT criteria, DL 1 was expanded with 3 additional patients, none of whom experienced DLT. Overall, the most common non hematologic adverse events (inclusive of intensive chemotherapy periods) were febrile neutropenia, nausea, and diarrhea. Based on this clinical experience and compiled pharmacokinetic data demonstrating lack of benefit to further dose escalation, 400 mg BID was selected as the recommended phase 2 dose. Responses were seen at both levels. Among the 3 patients treated at 200 mg BID, two required a second induction but all achieved a complete remission (CR) (3/3; 100%). Of the 6 patients treated at 400mg BID, none required a second induction and the CR rate was also 100%. Remarkably, an 18 year old male with 11q23-rearranged AML achieved morphologic and cytogenetic CR after only the 14 day entospletinib monotherapy window (prior to chemotherapy). Another patient with 11q23-rearranged AML had significant platelet response during the window period (this patient refused disease evaluation by marrow aspiration prior to chemotherapy). Conclusions: Entospletinib appears to have significant clinical activity in AML, and its combination at doses up to 400mg BID with intensive chemotherapy is well tolerated. An extended phase 2 program is now underway. Patients with 11q23-rearranged AML may be uniquely sensitive to SYK inhibition by entospletinib. Detailed molecular analysis of these patients is ongoing and will be presented. Disclosures Walker: Gilead Sciences: Research Funding. Bhatnagar:Karyopharm: Research Funding. Marcondes:Gilead Sciences: Employment, Equity Ownership. DiPaolo:Gilead Sciences: Employment, Equity Ownership. Abella-Dominicis:Gilead Sciences: Employment, Equity Ownership.

Description: Acute myeloid leukemia (AML) is an incurable disease with 5 year survival rates of 10% in patients over 60 years. Poor tolerance to chemotherapy, chemo resistance and high rate of relapse warrants less toxic and more effective regimens in AML. OSU-2S is a novel non-immunosuppressive derivative of FTY720, a sphingosine analogue. The promising in-vitro and in-vivo activity of OSU-2S against a number of leukemias and lymphomas, and other malignancies such as hepatocellular carcinoma, impelled us to evaluate the activity of OSU-2S in AML. The potent cytotoxic activity of the OSU-2S (5µM, 24hrs) in AML cell lines HL-60, MV411 and MOLM13 (n=3; HL-60: p=0.008; MV411: p=0.04; MOLM13: p=0.0094) encouraged us to evaluate the effect of OSU-2S in primary leukemic cells from AML patients. OSU-2S (5µM, 24 and 48 hrs) demonstrated significant cytotoxic activity against AML cells, including high risk FLT3-ITD mutated AMLs, (n=13, p

Description: Introduction: The optimal treatment approach for systemic AL amyloidosis remains unclear. Autologous stem cell transplant (ASCT) is the only modality associated with long term survival, but failure to show survival benefit in randomized clinical trial raises doubts about its efficacy 1, 2. Outcomes after ASCT are better in patients who achieve complete hematologic response after the ASCT3. One report has shown improved outcomes with combining one dose of the proteasome inhibitor bortezomib with high dose melphalan as part of conditioning regimen 4. Preliminary data from a recent study suggest that the outcome of treating AL amyloidosis with two cycles of bortezomib and dexamethasone followed by ASCT was superior to the outcome of the ASCT alone5. We describe our experience with giving 4-6 cycles of bortezomib and dexamethasone induction prior to high dose melphalan and ASCT in patients with systemic AL amyloidosis. Patients and methods: We included all patients who underwent autologous transplant for symptomatic systemic AL amyloidosis at our institution from October 2010 till June 2014. Five patients were included in the analysis and patient characteristics are described in table 1. All patient received 4 -6 cycles of induction with bortezomib and dexamethasone followed by autologous stem cell transplant using high dose melphalan (200 mg/m2). One patient also received six cycles of lenalidomide and dexamethasone prior to bortezomib based induction for lack of response. Hematologic and organ response were assessed using the definitions from the 10th International symposium on Amyloid and Amyloidosis. Overall survival was calculated by Kaplan Meyer’s method using Graphpad Prism 6.0 software. Results: There was no transplant related mortality. After median follow up of 13 months (12-25 months) all patient are alive. Toxicities from the ASCT were mostly cytopenias in the immediate post-transplant period which were managed as per the standard of care. Two patients achieved hematological complete response while one more had very good partial response and other two achieved partial response. Of the four patients with nephrotic range proteinuria, two patients had 〉 95% reduction in proteinuria, one had 〉 75% reduction in proteinuria and another patient had 〉 50% reduction in proteinuria. One patient had Liver involvement with elevated alkaline phosphatase which normalized post-transplant (table 2). The responses were maintained on last follow up and none of the patient had hematological or organ relapses. Discussion: Bortezomib alone and in combination with steroids has shown efficacy in AL amyloidosis, but its role in induction prior to high dose melphalan/ASCT to help achieve deeper hematological response is unknown. Our experience shows that this combination may be highly efficacious without significant toxicity. Limitations of our study include the small number of patients and absence of any patients with cardiac involvement, which is a worse prognostic marker. We conclude that the bortezomib and dexamethasone induction followed by high dose melphalan/ASCT for AL amyloidosis should be studied in prospective trials. Table 1.Patient Characteristics n=5Age, years 51.2 (44-62)Race (Caucasian)4 (80%)Gender ( female)3 (60%)Cardiac involvement 0 (0)Renal involvement 4 (80%)Serum creatinine ≥ 2.5 0 (0)Organ involvement ≥21 (20%)BM plasma cells 〉 10%1 (20%)Hgb ≤ 10 g/dl0 (0)LVEF 95% reduction, 1 〉75% reduction, 1 〉50 % reduction. Liver response n=1 Alkaline phosphatase 700 IU/L 62 IU/L Disclosures No relevant conflicts of interest to declare.

Description: Introduction Intensive treatment of acute myeloid leukemia (AML) is associated with severe pancytopenia. Thrombopoietic agents have so far failed to mitigate treatment-associated thrombocytopenia. Platelet factor 4 (PF4) is a potent negative regulator of megakaryopoeisis and its levels correlate with platelet transfusion requirements in children treated for acute lymphoblastic leukemia. Anti-PF4 antibodies diminish chemotherapy-induced thrombocytopenia in mice. ODSH (2-O, 3-O Desulfated Heparin), a heparin derivative with low anticoagulant activity, is a potent inhibitor of PF4, mitigates heparin-induced thrombocytopenia and, like other heparins, may inhibit the CXCL12/CXCR4 axis. The purpose of this pilot study was to obtain preliminary data on the effect of ODSH when combined with intensive AML treatment. Methods Adult patients with newly diagnosed untreated AML (excluding acute promyelocytic and acute megakaryoblastic leukemia) were enrolled. Induction therapy consisted of cytarabine (100 mg/m2 as a continuous 24-hour infusion on days 1 – 7) and idarubicin (12 mg/m2 by intravenous bolus on days 1 – 3). During induction cycles, ODSH was given as a bolus of 4 mg/kg on day 1 followed by a continuous infusion of 6 mg/kg/day on days 1 – 7. Patients 60 or older received further post-induction therapy off study. Patients younger than 60 received consolidation therapy with high dose cytarabine (3 g/m2 every 12 hours on days 1, 3, and 5) along with ODSH given as a bolus of 4 mg/kg on day 1 followed by a continuous infusion of 6 mg/kg/day on days 1 – 5. Patients received transfusion and antibiotic support per standard guidelines. Patients did not receive growth factor support during induction cycles. Primary endpoints were to determine the safety and tolerability of ODSH combined with intensive AML therapy, and to obtain preliminary data on the effect of ODSH on platelet count recovery. Secondary endpoints included obtaining preliminary data on the effect of ODSH on complete remission rate and tolerability of chemotherapy. Data presented here are for induction cycles. Data for consolidation cycles will be presented at the meeting. Results Ten patients were enrolled. Two patients did not complete the full induction cycle due to complications unrelated to ODSH therapy and are not included in the analysis. The median age of the 8 patients (3 women) who completed the full induction cycle and were analyzed was 55 (range: 22 – 74). There were no ODSH-associated adverse events. Based on cytogenetic, molecular, or antecedent hematologic disorder, 1, 5, and 2 patients fell into the better, intermediate, and poor risk categories, respectively. Day 14 bone marrow biopsies were obtained on all 8 patients and were aplastic without detectable leukemia in all. Seven out of 8 patients who completed induction had evidence of a morphologic complete remission upon count recovery using IWG criteria. One of the 7 patients in morphologic remission had evidence of minimal residual disease by flow cytometry and cytogenetics. It is noteworthy that the 2 patients who did not receive a full course of induction therapy (treatment discontinued on Day 3 and Day 5 of the induction cycle, respectively) achieved a complete remission upon count recovery using IWG criteria with evidence of minimal residual disease by molecular testing. All 8 patients who received a full course of induction therapy were evaluable for platelet count recovery. Among those patients, the median day to obtain a sustained platelet count above 20,000/ml without transfusion was day 20 (range: 16 – 22). Five of the 8 patients who received a full course of induction therapy were evaluable for neutrophil count recovery. Among those patients, the median day to a neutrophil count above 1,000/mL was day 23 (range: 21 – 27). Conclusion We conclude that ODSH is well tolerated when combined with aggressive therapy for the treatment of AML. Results from this pilot study show that ODSH may enhance count recovery and treatment efficacy. These results justify further study of this strategy in a randomized trial. Disclosures Kennedy: Cantex Pharmaceuticals: Equity Ownership. Bavisotto:Cantex Pharmaceuticals: Consultancy. Marcus:Cantex Pharmaceuticals: Employment, Equity Ownership. Shami:JSK Therapeutics: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Lone Star Thiotherapies: Equity Ownership; Cantex Pharmaceuticals: Research Funding.

Description: Background: Consolidation therapy with allogeneic hematopoietic stem cell transplant (HSCT) is recommended to prevent relapse and improve survival in patients with intermediate and poor risk acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). Due to toxicity, older patients with comorbidities were historically not candidates for HSCT. The development of reduced-intensity conditioning (RIC) regimens has allowed more patients to proceed to HSCT by reducing toxicities associated with myeloablative conditioning (MAC).The cornerstone of reducing conditioning regimen intensity is modification of busulfan exposure, expressed as an area under the curve (AUC). This can be achieved by the use of patient-specific pharmacokinetic targets. Previous studies (including BMT CTN 0901) have demonstrated RIC regimens were associated with less toxicity at the cost of potentially decreased survival relative to weight-based MAC regimens. At OSU, we have utilized an AUC target of 4,000 μmol-min/L per day x 4 days in a subset of patients to balance reduced toxicity with risk of relapse. Here we compare outcomes of AUC 4,000 to weight-based RIC Flu/Bu2. Methods: To compare the two regimens, a retrospective, IRB-approved cohort study was conducted. The inclusion criteria were as follows: age 18-89 years, HSCT for a diagnosis of AML or MDS, and fludarabine + busulfan conditioning regimen ± antithymocyte globulin. In the AUC 4,000 group, the target busulfan exposure was 16,000 μmol-min/L divided over 4 daily doses. In the RIC group, patents received busulfan 0.8 mg/kg/dose for 8 doses (Flu/Bu2). The primary outcome was relapse free survival (RFS). Secondary outcomes included overall survival (OS); time to neutrophil recovery; time to platelet recovery; incidence of acute and chronic graft vs host disease (GVHD); sinusoidal obstructive syndrome; febrile neutropenia; graft failure; and grade 3-5 mucositis, acute kidney injury, or hepatic dysfunction. The log-rank test was used to compare RFS and OS, and Cox proportional hazard regression model was used to estimate the hazard ratio. Gray's test was used for competing risks analysis of relapse, acute GVHD, and chronic GVHD. Fine and Gray regression models were used to estimate the hazard ratio. Results: Seventy-four patients who received conditioning from 2015-2018 with either AUC 4,000 or RIC were identified. Disease type was similar between groups with 61.8% AML in the AUC 4,000 group and 52.5% in the RIC group. There were no significant differences in disease risk status. In the AUC 4,000 group, 17.6% had either AML with myelodysplastic changes or therapy-related AML/MDS, compared to 17.5% in the RIC group. The percent of patients with HCT-Comorbidity Index score of ≥ 3 was 52.9% for AUC 4,000 and 77.5% for RIC. At 18 months, RFS was not significantly different, at 66.9% with AUC 4,000 compared to 57.5% with RIC (p=0.37) (A). Eighteen-month overall survival was also not significantly different with 66.9% alive in the AUC 4,000 group and 60% in the RIC group (p=0.63) (B). Cumulative incidence of acute and chronic GVHD were not significantly different (p=0.82, p=0.18, respectively) (C,D). There was, however, a statistically significant difference in the cumulative incidence of relapse over 18 months in favor of the AUC 4,000 regimen (hazard ratio 4.08, 95% confidence interval 1.15-14.5) (E). Grade 2-4 mucositis was more common in the AUC 4,000 group (85.3% vs 30%, p

Description: Background: NGS of myeloid mutations is an integral part of AML clinical decision-making. There is currently no information regarding concordance between NGS panels in AML using samples from the same patient across various platforms in different diagnostic laboratories. To study this important question, we analyzed NGS of myeloid mutations in diagnostic samples from The Beat AML Master Trial (BAMT) for newly diagnosed older AML patients, and compared variant calls made between institutional laboratories enrolling the study subject with those made by Foundation Medicine (FM), the central laboratory used for treatment assignment in this precision medicine trial. Methods: We identified newly diagnosed AML patient samples (peripheral blood (PB) and/or bone marrow (BM)) from 2 lead institutions in the BAMT(Ohio State, OSU and Oregon Health and Sciences University, OHSU) that were analyzed by both the institutional and by FM from Nov 15, 2016 to Apr 15, 2019. Samples sent to both laboratories 〉3 days apart were excluded. Samples were analyzed at the institutional laboratories using their respective NGS mutational panels and by FM using the FoundationOne®Heme(FMH) NGS panel which utilizes capture based sequencing. The OSU NGS assay utilizes sequencing on Illumina MiSeq. The OHSU NGS assay employs semiconductor-based sequencing (Ion Torrent PGM platform). The variant allele frequency (VAF) sensitivity for detection for all 3 laboratories range from 1-2%. We evaluated the ability to identify mutations in 8 genes : FLT3, IDH1/ 2, NPM1, TET2, DNMT3A, WT1 and TP53 used in treatment assignment in theBAMT. A detection cutoff of 2% was used to define the presence or absence of a mutation. Overall, agreement was defined as the number of times the local and central laboratories made the same call divided by the total number of patients. Sensitivity was defined as the number of present calls made locally divided by the number of present calls made centrally, and specificity as the number of absent calls made locally divided by the number of absent calls made centrally. The overall kappa statistic, controlling for institution, provided another measure of agreement between local and central calls, where a value of 1 indicates perfect agreement. Results: 194 patient samples were identified using methods above and analyzed locally at the screening institution (125 at OSU, 69 at OHSU) and centrally at FM. Type of tissue analyzed for variants between local site and FM were 59 PB, 129 BM, and 6 with BM/PB mismatch. Overall agreement in presence/absence calls between local and central results for each of the 8 genes was over 95% (Table 1). There was perfect agreement for NPM1. The sensitivity was above 94% for all genes except TP53 (88.6%) and WT1 (63.6%). Failure to detect a mutation locally was primarily due to reporting of all TP53 variants, including variants of unknown significance (VUS) (5) by FM as agreed upon in the study protocol, detection at low levels below local site sensitivity cutoff (1), detection of variants in a portion of gene not covered at the local site(1)and possible artifact (1). For the WT1 gene, discordance in 5 samples included VUS (3) reported by FM ,a variant detected in a portion of the gene not covered at the local site(1).and difference in leukemic tissue analyzed with mutation not detected by the central laboratory on a PB sample, and present at the institutional lab on a BM sample; affecting the overall agreement and specificity but not sensitivity. Specificity was at least 98% for each of the 8 genes. Finally, most discrepancies in reported mutations in FLT3 (n=2), IDH1 (n=1), IDH2 (n=2), DNMT3A (n=4) and TET2 (n=5) were due to reporting of VUS in one laboratory and not by another. Conclusion: Detection of pathogenic myeloid mutations using orthogonal assays showed a high degree of concordance for genes used in therapeutic assignment on the BAMT.The small number of discordant results, in TP53 and WT1, were attributed to the reporting of VUS. This study illustrates the importance of quality control and standardization as NGS continues to be widely utilized in AML for clinical decision making, with a variety of platforms across multiple laboratories. Our next steps involve evaluating the differences in VAFs reported between local and central laboratories when a given mutation is identified, as well as the potential reasons for observed differences and clinical implications of known pathogenic mutations vs putative VUS. Disclosures Borate: Daiichi Sankyo: Consultancy; AbbVie: Consultancy; Novartis: Consultancy; Takeda: Consultancy; Pfizer: Consultancy. Vergilio:Foundation Medicine: Employment; Roche Holding AG: Equity Ownership. Stein:Novartis: Membership on an entity's Board of Directors or advisory committees; Celgene Corporation: Membership on an entity's Board of Directors or advisory committees; Daiichi Sankyo, Inc.: Membership on an entity's Board of Directors or advisory committees; Agios: Consultancy, Membership on an entity's Board of Directors or advisory committees; Astellas Pharma US, Inc: Membership on an entity's Board of Directors or advisory committees; Bioline: Membership on an entity's Board of Directors or advisory committees; Genentech: Membership on an entity's Board of Directors or advisory committees; PTC Therapeutics: Membership on an entity's Board of Directors or advisory committees; Syros: Membership on an entity's Board of Directors or advisory committees. Patel:France Foundation: Honoraria; Dava Oncology: Honoraria; Celgene: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Baer:Astellas: Research Funding; Abbvie: Research Funding; AI Therapeutics: Research Funding; Forma: Research Funding; Incyte: Research Funding; Kite: Research Funding; Takeda: Research Funding. Stock:Daiichi: Membership on an entity's Board of Directors or advisory committees; Astellas: Membership on an entity's Board of Directors or advisory committees; Agios: Membership on an entity's Board of Directors or advisory committees; Research to Practice: Honoraria; UpToDate: Honoraria; Kite, a Gilead Company: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees. Schiller:Amgen: Other, Research Funding; Astellas: Research Funding; Biomed Valley Discoveries: Research Funding; Bristol Myer Squibb: Research Funding; Celgene: Research Funding, Speakers Bureau; Constellation Pharmaceutical: Research Funding; Daiichi Sankyo: Research Funding; Eli Lilly and Company: Research Funding; FujiFilm: Research Funding; Genzyme: Research Funding; Gilead: Research Funding; Incyte: Research Funding; J&J: Research Funding; Jazz Pharmaceuticals: Honoraria, Research Funding; Karyopharm: Research Funding; Novartis: Research Funding; Onconova: Research Funding; Pfizer Pharmaceuticals: Equity Ownership, Research Funding; Sangamo Therapeutics: Research Funding; Agios: Research Funding, Speakers Bureau. Blum:AmerisourceBergen: Consultancy; Boehringer Ingelheim: Research Funding; Celgene: Research Funding; Astellas,: Research Funding; Xencor: Research Funding; Forma: Research Funding. Kovacsovics:Pfizer: Research Funding; Jazz: Consultancy; Novartis: Research Funding; Abbvie: Research Funding; Amgen: Consultancy, Research Funding. Foran:Agios: Honoraria, Research Funding. Druker:Pfizer: Research Funding; OHSU (licensing fees): Patents & Royalties: #2573, Constructs and cell lines harboring various mutations in TNK2 and PTPN11, licensing fees ; Cepheid: Consultancy, Honoraria; Aileron Therapeutics: #2573, Constructs and cell lines harboring various mutations in TNK2 and PTPN11, licensing fees , Membership on an entity's Board of Directors or advisory committees; ALLCRON: Membership on an entity's Board of Directors or advisory committees; Amgen: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Aptose Biosciences: Consultancy, Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Beta Cat: Membership on an entity's Board of Directors or advisory committees, Other: Stock options; GRAIL: Equity Ownership, Other: former member of Scientific Advisory Board; Patient True Talk: Consultancy; The RUNX1 Research Program: Membership on an entity's Board of Directors or advisory committees; Vivid Biosciences: Membership on an entity's Board of Directors or advisory committees, Other: Stock options; Beat AML LLC: Other: Service on joint steering committee; CureOne: Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy; Gilead Sciences: Other: former member of Scientific Advisory Board; ICON: Other: Scientific Founder of Molecular MD, which was acquired by ICON in Feb. 2019; Monojul: Other: former consultant; Novartis: Other: PI or co-investigator on clinical trial(s) funded via contract with OHSU., Patents & Royalties: Patent 6958335, Treatment of Gastrointestinal Stromal Tumors, exclusively licensed to Novartis, Research Funding; Bristol-Myers Squibb: Other: PI or co-investigator on clinical trial(s) funded via contract with OHSU., Research Funding; Pfizer: Other: PI or co-investigator on clinical trial(s) funded via contract with OHSU., Research Funding; Merck & Co: Patents & Royalties: Dana-Farber Cancer Institute license #2063, Monoclonal antiphosphotyrosine antibody 4G10, exclusive commercial license to Merck & Co; Dana-Farber Cancer Institute (antibody royalty): Patents & Royalties: #2524, antibody royalty; Burroughs Wellcome Fund: Membership on an entity's Board of Directors or advisory committees; Blueprint Medicines: Consultancy, Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Patents & Royalties, Research Funding. Byrd:Gilead: Other: Travel Expenses, Research Funding, Speakers Bureau; Genentech: Research Funding; Acerta: Research Funding; TG Therapeutics: Other: Travel Expenses, Research Funding, Speakers Bureau; Novartis: Other: Travel Expenses, Speakers Bureau; Pharmacyclics LLC, an AbbVie Company: Other: Travel Expenses, Research Funding, Speakers Bureau; Janssen: Consultancy, Other: Travel Expenses, Research Funding, Speakers Bureau; BeiGene: Research Funding; Ohio State University: Patents & Royalties: OSU-2S. Levine:C4 Therapeutics: Membership on an entity's Board of Directors or advisory committees; Isoplexis: Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Research Funding; Roche: Consultancy, Research Funding; Loxo: Membership on an entity's Board of Directors or advisory committees; Qiagen: Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria; Prelude Therapeutics: Research Funding; Novartis: Consultancy; Gilead: Consultancy; Lilly: Honoraria; Imago Biosciences: Membership on an entity's Board of Directors or advisory committees. Mims:Jazz Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Astellas Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; PTC Therapeutics: Membership on an entity's Board of Directors or advisory committees; Agios Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees.

Description: Introduction: NPM1 gene mutations are a common molecular aberration in acute myeloid leukemia (AML). In the absence of concurrent high FLT3-ITD ratio mutations (〉0.5), NPM1 mutations typically associate with higher complete remission (CR) rates following intensive induction chemotherapy. NPM1 mutations have been shown to be stable markers of persistent disease or impending relapse during CR or complete remission with incomplete count recovery (CRi). Given the clinical implications that persistent NPM1 mutations can have during CR/CRi, we used Deep Amplicon sequencing on CR/CRi bone marrow (BM) samples collected from adult de novoNPM1-mutated AML patients to determine the ability of NPM1 mutations at both a high and lower sensitivity next generation sequencing methods and also the presence of additional clonal abnormalities on relapse risk. Methods: We performed targeted next generation sequencing (NGS) analysis in addition to NPM1 Deep Amplicon sequencing on paired BM or blood samples collected from 38 newly diagnosed NPM1-mutated AML patients during CR/CRi after successful induction (1-2 courses of 7 + 3) and, if available, at relapse. NPM1 mutated NGS libraries were prepared using a KAPA HyperPlus Kit (Roche, Pleasanton, CA) and xGen Lockdown Probes (IDT, Coralville, IA). Libraries were sequenced using the Illumina HiSeq 4000 (Illumina, San Diego, CA). GATK's MuTect2 was used to perform variant calling. Variant allele frequency (VAF) cut-off for the NGS panel was 0.05 (5%) with the exception of hotspot variants in IDH1 (R132) and IDH2 (R140) where variants detected to a level of 0.01 (1%) were included. The VAF cut off used for NPM1 Deep Amplicon sequencing was 0.00012 (0.012%). Results: Targeted NGS analysis and NPM1 Deep Amplicon sequencing had exceptional concordance at the level of detection of VAF= 0.05 (Figure 1). Of 38 patients, 23 patients had undetectable NPM1 mutations as analyzed through NPM1 Deep Amplicon sequencing of whom 9 (38.1%) relapsed. In contrast, 15 patients were positive by NPM1 Deep Amplicon sequencing and 9 (60%) relapsed. Only 4 patients had detectable persistent NPM1 mutations after induction according to both detection techniques and two of these relapsed. We next examined the potential impact of clearing both NPM1 mutation and co-occurring mutations together on relapses (Figure 2). A total of 15 patients cleared all of their clonal abnormalities and 5 (27%) relapsed. In contrast, of the 23 patients who did not clear the NPM1 mutation and/or another co-occurring mutation at remission, 14 (61%) have relapsed. Eleven of the relapsed patients had relapse samples available of whom all had persistent NPM1 mutation at this time. Paired CR/CRi and relapsed samples showed acquisition or recurrence of several other mutations, most notably FLT3-ITD, IDH1, and IDH2 which are all targetable with small molecule therapeutics. Conclusions: The use of Deep Amplicon sequencing to identify NPM1 mutations at a lower detection threshold compared to standard NGS techniques was more sensitive, but did not appear to fully inform relapse rates in NPM1-mutated AML patients after receipt of induction therapy. The appearance of other AML-associated mutations, identified together with NPM1 at time of remission, was more frequent among patients relapsing. These pilot data provide support for concurrent assessment of Deep Amplicon sequencing together with a broad standard NGS AML mutational assay to further enhance risk stratification of NPM1-mutated patients. Additionally, while NPM1 clones are present in all patients examined at the time of relapse, persistence or development of targetable clones justifies repeat broad NGS sequencing at this time. Figure Disclosures Bhatnagar: Novartis and Astellas: Consultancy, Honoraria; Cell Therapeutics, Inc.: Other: Research support; Karyopharm Therapeutics: Other: Research support. Mims:Agios Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Astellas Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Jazz Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees; PTC Therapeutics: Membership on an entity's Board of Directors or advisory committees. Behbehani:Fluidigm corporation: Other: Travel funding. Byrd:Novartis: Other: Travel Expenses, Speakers Bureau; TG Therapeutics: Other: Travel Expenses, Research Funding, Speakers Bureau; Genentech: Research Funding; Pharmacyclics LLC, an AbbVie Company: Other: Travel Expenses, Research Funding, Speakers Bureau; BeiGene: Research Funding; Janssen: Consultancy, Other: Travel Expenses, Research Funding, Speakers Bureau; Acerta: Research Funding; Gilead: Other: Travel Expenses, Research Funding, Speakers Bureau; Ohio State University: Patents & Royalties: OSU-2S.