ALBERT

Beschreibung: The 2016 revision of the World Health Organization classification of tumors of hematopoietic and lymphoid tissues is characterized by a closer integration of morphology and molecular genetics. Notwithstanding, the myelodysplastic syndrome (MDS) with isolated del(5q) remains so far the only MDS subtype defined by a genetic abnormality. Approximately half of MDS patients carry somatic mutations in spliceosome genes, with SF3B1 being the most commonly mutated one. SF3B1 mutation identifies a condition characterized by ring sideroblasts (RS), ineffective erythropoiesis, and indolent clinical course. A large body of evidence supports recognition of SF3B1-mutant MDS as a distinct nosologic entity. To further validate this notion, we interrogated the data set of the International Working Group for the Prognosis of MDS (IWG-PM). Based on the findings of our analyses, we propose the following diagnostic criteria for SF3B1-mutant MDS: (1) cytopenia as defined by standard hematologic values, (2) somatic SF3B1 mutation, (3) morphologic dysplasia (with or without RS), and (4) bone marrow blasts

Beschreibung: Background: Myelodysplastic syndromes (MDS) have been associated with alterations in the bone marrow microenvironment and include abnormal innate and adaptive immune responses. The extent to which these changes contribute to the pathogenesis of MDS is unclear. The heterogeneous nature of MDS makes it difficult to distinguish changes in intrinsic cell function for microenvironmental alterations in the mutated myeloid compartment. T cells, which are in the lymphoid compartment and less frequently contain MDS mutations, can potentially be used to evaluate immune dysfunction in the presence of malignant myeloid cells. Here we examine the immunophenotypes and proliferative function of T lymphocyte and monocyte populations from higher-risk MDS patients. Methods: Peripheral blood mononuclear cells (PBMC) from patients with IPSS-R Intermediate/High/Very High-risk MDS (herein referred to collectively as higher-risk MDS) and age-matched healthy donors (n = 15 and n = 12, respectively) were polyclonally stimulated with an antibody against CD3 (OKT3) in the presence of IL-2 (50 U/mL). Phenotypic analysis was performed at baseline and 46 hours after the addition of OKT3 and IL-2. T cell proliferation was measured by staining PBMC with proliferation dye (CellTrace Violet) and measuring fold proliferation after eight days in culture. Proliferation statistical comparisons were made by unpaired t-test. Phenotypic parameters were measured by flow cytometry and statistical analysis performed with the Kruskal-Wallis one-way analysis. Results: As previously reported, higher-risk MDS patient T cells had decreased capacity for proliferation when compared to healthy donor counterparts (Figure 1A p = 0.0096). This difference in proliferative capacity was not associated with either the level of PD-1 on the surface of T cells (r = 0.2956) or the level of PD-L1 on monocytes (r = 0.3859) in stimulated PBMCs. Patients with higher-risk MDS tended to have lower PD-L1 surface expression on monocytes compared to healthy donor counterparts, albeit not significantly (Figure 1C p = 0.1). However, PD-1 expression on T cells was comparable between groups both before and after stimulation (Figure 1B CD4 cells: p = 0.58; CD8 cells p = 0.58). This suggests that T cell proliferation from patients with higher-risk MDS might not be inhibited through the PD-1/PD-L1 axis. Of note, higher-risk MDS patient monocytes expressed less CD80 and HLA-DR both pre- and post-stimulation when compared to healthy donors (Figure 1C CD80: p = 0.0001 and 0.037; DR: p = 0.012 and 0.019, respectively), implying a potential dysfunction in the monocytic stimulatory and antigen presentation capacity. PD-L1 surface expression is low at baseline (an average of

Beschreibung: INTRODUCTION: CG-806 is a potent, non-covalent oral inhibitor of Bruton's tyrosine kinase (BTK), FMS-like tyrosine kinase 3 (FLT3) and certain other validated driver kinases of malignancies, while sparing kinases typically associated with clinical toxicity. In cell lines and primary samples from chronic lymphocytic leukemia (CLL) patients, CG-806 suppressed BCR signaling (LYN, SYK, BTK, AKT, ERK) and pathways operative in AML (FLT3, AKT, CSF1R, MAPK, PDGFRα, others), killed malignant B-cell cells insensitive to ibrutinib or venetoclax at low nM concentrations, and showed enhanced activity in combination with venetoclax. CG-806 is currently being evaluated in a Phase 1 a/b trial in patients with CLL and select relapsed or refractory B-cell malignancies (NCT03893682). A parallel Phase 1 a/b clinical study of CG-806 in patients with relapsed or refractory (R/R) FLT3-mutant or FLT3-wildtype AML is in progress (NCT04477291). AIMS: The primary objectives of the clinical study NCT03893682 are to assess the safety and tolerability of CG-806 and to determine the recommended Phase 2 dose for future clinical trials in patients with advanced CLL/small lymphocytic lymphoma (SLL) or non-Hodgkin lymphoma (NHL). Key secondary objectives include elucidation of the pharmacokinetic (PK) and pharmacodynamic (PD) characteristics, preliminary evidence of antitumor activity, and selection of a starting dose for a trial in patients with R/R AML. METHODS: Eligible patients are those with CLL/SLL or NHL for which either the standard treatment has failed, is no longer effective, or can no longer be administered safely. Treatment emergent adverse events (TEAEs) and tumor responses are evaluated per disease specific guidelines. CG-806 is administered as capsules PO BID in 28-day cycles. RESULTS: As of July 24, 2020, a total of 11 patients (age 66.2 ± 7.4 years, male 54.5%, female 45.5%, 5 CLL/SLL, 3 follicular lymphoma, 1 Richter transformation lymphoma, 1 Waldenstrom's macroglobulinemia, 1 mantle cell lymphoma) with a median of 7 prior systemic regimens have been treated with CG-806 at doses of 150 mg (n=1), 300 mg (n=1), 450 mg (n=5), and 600 mg (n=4). No dose limiting toxicities or related serious adverse event have been reported. The most common drug related or possible related TEAEs included diarrhea, nausea, neutropenia in 3 (27.3%) each; fatigue, lymphocytosis and vomiting in 2 (18.2%) patients each. Drug related or possible related grade 3 or greater TEAEs included diarrhea (n=1, 9.1%) and neutropenia (n=2, 18.2%), but no fevers were reported - those two neutropenia events occurred in a patient with Richter transformation from CLL who had failed 12 prior regimens including ibrutinib, venetoclax, binutuzumab, CAR-NK and CAR-T and was found to have a prior therapy-related myeloid neoplasm after enrollment. Among three classic CLL patients placed on study, all experienced on-target lymphocytosis upon initiation of CG-806 therapy, as well as inhibition of phospho-BTK measured in the whole blood by ELISA and measured by a plasma inhibitor activity (PIA) assay with reporter cells. Steady state plasma levels of CG-806 in patients treated with CG-806 at 300 mg or higher doses dramatically reduced phosphorylated BTK-Y551, BTK-Y223, SYK-Y525/526, ERK-T202/Y204 and FLT3-Y591 in EOL-1 reporter cells, as determined by PIA assay, documenting multi-target engagement. Preliminary PK analyses showed the steady-state (Cmin) plasma levels of CG-806 on cycle 2 day 1 in patients treated with ≥300 mg BID were generally in the 1µM range and were sustained over multiple cycles. CONCLUSIONS: CG-806 demonstrated a favorable safety profile in patients treated to date with 150, 300, 450 or 600 mg BID over multiple cycles. Oral absorption in patients produced plasma concentrations known to be effective in murine leukemia models. Pharmacodynamic studies using patient whole blood and plasma documented inhibition of SYK, BTK and ERK in the BCR signaling pathway. Further, the trial allowed selection of a potentially therapeutically active starting dose for AML patients (450mg). Enrollment of patients with R/R CLL/SLL and NHL at dose level 5 (750mg) is ongoing and updated clinical data will be presented at the meeting. Disclosures Bejar: Aptose Biosciences, Inc: Current Employment, Current equity holder in publicly-traded company. Zhang:Aptose Biosciences, Inc.: Current Employment, Current equity holder in publicly-traded company. Rastgoo:Aptose Biosciences, Inc.: Current Employment, Current equity holder in publicly-traded company. Benbatoul:Aptose Biosciences, Inc.: Current Employment, Current equity holder in publicly-traded company. Jin:Aptose Biosciences, Inc.: Current Employment, Current equity holder in publicly-traded company. Thayer:Aptose Biosciences, Inc.: Current Employment, Current equity holder in publicly-traded company. Sheng:Aptose Biosciences, Inc.: Current Employment, Current equity holder in publicly-traded company. Chow:Aptose Biosciences, Inc.: Current Employment, Current equity holder in publicly-traded company. Montalvo-Lugo:Aptose Biosciences, Inc.: Current Employment, Current equity holder in publicly-traded company. Marango:Aptose Biosciences, Inc.: Current Employment, Current equity holder in publicly-traded company. Howell:Aptose Biosciences, Inc.: Current equity holder in publicly-traded company. Rice:Aptose Biosciences, Inc.: Current Employment, Current equity holder in publicly-traded company.

Beschreibung: INTRODUCTION: APTO-253 is the only known small molecule in clinical development to target a conserved G-quadruplex structure in the promoter of the MYC oncogene and interrupt MYC gene expression. In preclinical studies of acute myeloid leukemia (AML) cell lines, APTO-253 potently down-regulates MYC gene expression, reduces MYC mRNA and protein level, depletes cells of the MYC oncoprotein and induces apoptosis (Local et al., 2018). APTO-253 demonstrated broad killing of primary mononuclear cells isolated from the bone marrow of patients with AML, MDS, or MPN and enhanced AML cell killing when combined with BET bromodomain inhibitors or FLT3 inhibitors (Kurtz, et al., 2017). Fe(253)3, a ferrous complex formed from parental APTO-253 when it chelates iron, exhibits similar in vitro anti-tumor potency as its monomeric form (Tsai, et al., 2018). Because dysregulated MYC is considered a major oncogenic operator in AML and myelodysplasias, and because APTO-253 has such a distinct cytotoxic mechanism, APTO-253 has been granted orphan drug designation for the treatment of AML by the US FDA and is currently in a Phase 1a/b clinical trial (NCT02267863) in patients with relapsed or refractory AML (R/R AML) or high-risk myelodysplasias (high-risk MDS). AIMS: Primary objectives are to determine the safety and tolerability of APTO-253, to determine the maximum tolerated dose and the dose limiting toxicities (DLT), and to establish the recommended Phase 2 dose for future clinical trials in patients with R/R AML or high-risk MDS. Key secondary objectives are to assess the pharmacokinetic (PK) profile, pharmacodynamic (PD) activity, and preliminary evidence of antitumor activity. METHODS: Eligible patients are those with R/R AML or high-risk MDS for which either standard treatment has failed, is no longer effective, or can no longer be administered safely. Treatment- emergent adverse events (TEAEs) and tumor responses are evaluated using International Working Group criteria. APTO-253 is administered by IV infusion once weekly on days 1, 8, 15, and 22 of each 28-day cycle; ascending dose cohorts will enroll at a starting dose of 20 mg/m2 with planned escalating to 403 mg/m2. RESULTS: As of July 28, 2020, a total of 10 patients (age 66.1 ± 13.58 years, male 50%, female 50%, 8 AML and 2 MDS) have been treated with APTO-253 in this clinical trial at doses of 20 mg/m2 (n=1), 40 mg/m2 (n=1), 66 mg/m2 (n=4), and 100 mg/m2 (n=4). All 8 AML patients and 1 MDS patient were RBC and platelet transfusion dependent; 1 MDS patient was RBC transfusion dependent. No DLTs or drug-related serious adverse events have been reported. Possible drug related grade 2 TEAEs included fatigue, increased alkaline phosphatase, decreased appetite, hematoma, hypokalemia, thrombophlebitis, upper respiratory tract in 1 (10%) patient each. Only 1 TEAE of grade 3 or greater (fatigue, considered possibly drug-related) has occurred to date. Preliminary PK analysis showed plasma levels of APTO-253 were dose proportional. Cmax and AUC0-24h on cycle 1 day 1 (C1D1) were 0.18, 0.07, 0.28 ± 0.15 and 0.77 ± 0.63 µM and 0.08, 0.13, 1.14 ± 0.57, 1.84 ± 0.41 µM*h for dose levels of 20 mg/m2, 40 mg/m2, 66 mg/m2, and 100 mg/m2, respectively. Not surprisingly, Fe(253)3 was detected in the patients' plasma immediately after dosing and at a significantly higher concentration than the APTO-253 monomer. For example, Cmax and AUC0-24h of Fe(253)3 on C1D1 of patients in Cohort 66 mg/m2 were 3- and 8-fold higher than the monomer at 0.92 ± 0.29 µM and 20.61 ± 9.01 µM*h, respectively. The levels of MYC mRNA in the whole blood, a PD biomarker of APTO-253 and Fe(253)3 measured by RT-qPCR, were reduced 20-48% at 24 h post-dose as compared to pre-dose in the first 3 cohorts (other samples of Cohort 100 mg/m2 in process), suggesting target engagement by the drug. CONCLUSIONS: APTO-253 has been well-tolerated in patients treated with 20, 40, 66, and 100 mg/m2 over multiple cycles. PK analysis revealed APTO-253 monomer rapidly transformed to and co-existed with the Fe(253)3 complex in peripheral blood and their exposures resulted in suppression of MYC expression in whole blood samples from R/R AML and high-risk MDS patients. Enrollment of patients at the 150 mg/m2 dose level is underway and updated clinical data will be presented at the meeting. Disclosures Bejar: Aptose Biosciences, Inc: Current Employment, Current equity holder in publicly-traded company. Zhang:Aptose Biosciences, Inc.: Current Employment, Current equity holder in publicly-traded company. Rastgoo:Aptose Biosciences, Inc.: Current Employment, Current equity holder in publicly-traded company. Benbatoul:Aptose Biosciences, Inc.: Current Employment, Current equity holder in publicly-traded company. Jin:Aptose Biosciences, Inc.: Current Employment, Current equity holder in publicly-traded company. Thayer:Aptose Biosciences, Inc.: Current Employment, Current equity holder in publicly-traded company. Sheng:Aptose Biosciences, Inc.: Current Employment, Current equity holder in publicly-traded company. Chow:Aptose Biosciences, Inc.: Current Employment, Current equity holder in publicly-traded company. Montalvo-Lugo:Aptose Biosciences, Inc.: Current Employment, Current equity holder in publicly-traded company. Marango:Aptose Biosciences, Inc.: Current Employment, Current equity holder in publicly-traded company. Howell:Aptose Biosciences, Inc.: Current equity holder in publicly-traded company. Rice:Aptose Biosciences, Inc.: Current Employment, Current equity holder in publicly-traded company.

Beschreibung: Introduction: The NHLBI National MDS Study (NCT02775383) is a prospective cohort study conducted at 92 community hospitals and 29 academic centers. It enrolls patients undergoing work up for suspected MDS to understand the genetic, epigenetic, and biological factors associated with the initiation and progression of the disease. Previously untreated, cytopenic participants undergo both local and centralized pathology review and are assigned a diagnosis, including MDS, MDS/MPN, AML with blasts 〈 30%, and "Other". Emerging data suggests that Next Generation Sequencing (NGS), along with cytogenetics and clinical variables, may improve MDS diagnostic precision. Given that our study relies on central review (with additional tertiary pathology review used to adjudicate disagreements), we examined whether targeted gene sequencing data could be used to increase the agreement between local and central pathologic diagnosis of MDS vs. Other. Methods: Peripheral blood and bone marrow (BM) biopsy specimens from cytopenic patients, along with clinical history, CBC, and other results including karyotyping, FISH and pathology reports from local pathologists were reviewed by central pathologists. The updated 2016 WHO classifications were used to diagnose MDS. Targeted exon sequencing of 96 genes was performed using BM specimens. A subset of 648 individuals that were classified as MDS (n=212) or Other (n=436, including 90 CCUS and 89 individuals with other cancers) by pathology assessments were selected. A mean coverage of 1,317X was achieved and variants had a minimum variant allele frequency (VAF) of 2% (except FLT3). Variants for 596 subjects were manually reviewed to retain likely disease-causing variants to build a binary classifier (MDS vs. Other) using the maximum VAF per gene as input (Figure 1). Subjects diagnosed with MDS or Other by both central and local pathology were used for training, validation, and testing, and were considered "gold standard" (GS) cases (n=546). These subjects were split into 4 random groups with equal proportions of MDS cases. 75% of the GS cases were used to train and validate lasso-regularized logistic regression models using 3-fold cross validation. ROC curve analysis was carried out using the remaining 25% of GS cases (Test Set 1) on the best model to identify an optimal probability cut off point for classifying subjects as MDS. Model performance was then tested on 50 subjects for which the central and local pathology diagnosis disagreed (Test Set 2), as well as on 52 additional subjects irrespective of agreement (Test Set 3). Results : The best performing logistic regression model retained 7 genes as most informative in a discriminating diagnosis of MDS from Other based on their VAFs, in order of impact: TP53, SF3B1, U2AF1, ASXL1, TET2,STAG2, and SRSF2. We used this model to assign probabilities for each of the subjects in Test Set 1 and to estimate the performance using ROC analysis (Figure 1), resulting in a high area under the curve (AUC) of 0.89. We chose a probability cut-off of ≥0.17, being associated with a high percentage of correct classification of MDS with a sensitivity and specificity of 0.90 and 0.81, respectively. Among the cohort of 50 subjects with a discordant local and central pathology diagnosis (Test Set 2), the classifier accurately reassigned 37 subjects (accuracy = 74%) from the local to the central pathology. The blinded tertiary pathology reviewer agreed with central in all Test Set 2 cases. This included 24/34 MDS cases that had been labeled as Other by local pathology (positive predictive value [PPV]=0.89). 3/16 final pathology-classified Other cases were mis-classified as MDS by the local pathologist (negative predictive value [NPV] = 0.57). Next, we assessed the ability of the model to predict MDS vs. Other for 52 additional independent subjects using the third pathologist's diagnosis to break any ties (Test Set 3). The classifier correctly predicted 15/21 MDS cases (PPV=0.83) and misclassified 6/31 Others as MDS (NPV=0.82). The overall accuracy was 83%. Conclusions: We identified that VAFs for 7 genes can correctly re-classify subjects as either MDS or Other in 74% of cases that were misclassified between local and central pathology review. Further assessment on an independent cohort showed an accuracy of 83% of the model. Taken together, these data suggest that complementing pathology reviews with targeted sequencing of 7 genes could improve MDS diagnosis. Disclosures Lindsley: MedImmune: Research Funding; Jazz Pharmaceuticals: Consultancy, Research Funding; Bluebird Bio: Consultancy; Takeda Pharmaceuticals: Consultancy. Bejar:Aptose Biosciences: Current Employment; AbbVie/Genentech: Honoraria; Astex/Otsuka: Honoraria; Takeda: Honoraria, Research Funding; Celgene/BMS: Honoraria, Research Funding; Daiichi-Sankyo: Honoraria; Forty-Seven/Gilead: Honoraria; Genoptix/NeoGenomics: Honoraria. DeZern:MEI: Consultancy; Astex: Research Funding; Abbvie: Consultancy; Celgene: Consultancy, Honoraria. Foran:H3Biosciences: Research Funding; Aptose: Research Funding; Kura Oncology: Research Funding; Trillium: Research Funding; Takeda: Research Funding; Revolution Medicine: Consultancy; Xencor: Research Funding; Agios: Honoraria, Research Funding; Aprea: Research Funding; Actinium: Research Funding; Servier: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Abbvie: Research Funding; BMS: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees; Boehringer Ingelheim: Research Funding. Gore:Abbvie: Consultancy, Honoraria, Research Funding. Komrokji:Acceleron: Honoraria; Incyte: Honoraria; Abbvie: Honoraria; Agios: Speakers Bureau; BMS: Honoraria, Speakers Bureau; Jazz: Honoraria, Speakers Bureau; Geron: Honoraria; Novartis: Honoraria. Maciejewski:Alexion, BMS: Speakers Bureau; Novartis, Roche: Consultancy, Honoraria. Padron:Novartis: Honoraria; BMS: Research Funding; Incyte: Research Funding; Kura: Research Funding. Starczynowski:Captor Therapeutics: Consultancy; Tolero Therapeutics: Research Funding; Kurome Therapeutics: Consultancy, Current equity holder in private company, Research Funding. Sekeres:BMS: Consultancy; Takeda/Millenium: Consultancy; Pfizer: Consultancy.

Beschreibung: Background: Patients with MDS continue to report gaps in knowledge, particularly where understanding of disease risk, prognosis and treatment options are concerned.1 A recent online social media survey on experiences in myelodysplastic syndromes revealed that patients/caregivers' (n=127) have a general lack of information about MDS and insufficient knowledge regarding treatment options and are unable to make fully informed decisions.2 Efforts to improve patient and caregiver understanding of MDS, including treatment options, are critical to individualized treatment planning and shared decision-making. MDS patients commonly use multimedia and online resources to seek disease information.3 The MDSF introduced an online 'animated,' visual format educational program in July 2018 aimed at improving patient and caregiver knowledge.4 Evaluation of this project, including determining changes in patient knowledge and intent-to-implement a change in behavior are described as parameters of advancing and benefiting health outcomes. Methods: An Animated Patient's Guide to MDS (APG), a multimedia educational initiative was launched globally in July 2018. Recruitment was conducted via search engine marketing, social media promotions and email campaigns to MDS patients, caregivers and oncology provider audiences. Video views, duration of use, and learner responses to questions on the APG website were collected from July 2018 to July 2020 (24 months). Total APG views, most frequently viewed MDS animations and MDS expert videos were monitored on the website and on You Tube, to measure learner responses to outcome-based questions, and learner intent-to-implement changes. Results: A total of 151,231 views, including 58,947 unique visitors visited the APG online resource. Of these, 81% were from the U.S. and 19% from other countries (〉 50 countries). Unique visitors from U.S. consisted of 28,171 patients, 15,279 family/caregivers, and 1,910 health providers. Among responses indicating a 'commitment to change', 96% reported they will 'use new information learned to better self-manage their MDS' (n = 917), 93% reported they 'will discuss information learned with their doctor' (n = 355), and 97% reported they 'plan to discuss MDS treatment options with their doctor' (n = 734). Patients who reported they 'learned new information about MDS' identified that they 'learned new general information about MDS' (95%, n = 193), 'learned new information about the diagnosis of MDS' (86%, n = 195), 'learned about new treatment options for MDS' (89%, n = 195), 'learned about new information related to bone marrow transplant in MDS' (85%, n = 177) and intended to 'ask their doctor about how to take part in healthcare decisions' (96%, n = 187). Conclusion: Multimedia education, including visual 'animated' formats, tailored to the needs of MDS patients has the potential to provide effective learning, increase knowledge and improve engagement in shared decision-making. Ongoing monitoring and further analysis of this multimedia educational resource for MDS patients will be necessary to understand how tailored education provided via this format impacts and benefits patient health outcomes. References: 1. Kurtin, S., Chang, E., & Bently, T. (2015). MDS patient characteristics associated with use of disease-modifying therapy: results of a patient survey. The International MDS Symposia, Washington, D.C. 2. Booth, A., Bell, T., Halhol, S., Pan, S., Welch, V., Merinopoulou, E., Lambrelli, D., Cox, A. Using Social Media to Uncover Treatment Experiences and Decisions in Patients with Acute Myeloid Leukemia or Myelodysplastic Syndrome Who Are Ineligible for Intensive Chemotherapy. J Med Internet Res 2019 Nov; 21(11) e-14285 3. Kurtin, S., Harrison, L., Iraca, T., Hassan, A., Nichols, A. Health Technology Engagement and Communicative Health Literacy in Older Adults MDS Patients. Myelodysplastic Syndromes, 15th International Symposia on Myelodysplastic Syndromes. Copenhagen. May 8-1, 2019. Poster presentation. 4. MDS Foundation, Inc. and Mechanisms in Medicine Inc. (2019-06-26). You And MDS: An Animated Patient's Guide to Myelodysplastic Syndromes. www.YouAndMDS.com Disclosures Sallman: Agios, Bristol Myers Squibb, Celyad Oncology, Incyte, Intellia Therapeutics, Kite Pharma, Novartis, Syndax: Consultancy; Celgene, Jazz Pharma: Research Funding. Iraca:MDS Foundation: Membership on an entity's Board of Directors or advisory committees. Bejar:Celgene/BMS: Honoraria, Research Funding; Forty-Seven/Gilead: Honoraria; Genoptix/NeoGenomics: Honoraria; AbbVie/Genentech: Honoraria; Daiichi-Sankyo: Honoraria; Aptose Biosciences: Current Employment; Takeda: Honoraria, Research Funding; Astex/Otsuka: Honoraria. Kurtin:MDS Foundation: Membership on an entity's Board of Directors or advisory committees.

Beschreibung: Background: Clinical responses to hypomethylating agents (HMA) occur in the minority of patients with myelodysplastic syndromes (MDS) and related disorders and require months of treatment. Robust biomarkers of HMA response would have great clinical utility but remain elusive. Combinations of HMA and novel agents may improve response rates and latency and be associated with distinct biomarkers. Predictive baseline DNA methylation (DNAm) profiles have yet to be identified in MDS, although responders show more global hypomethylation after response occurs. DNAm changes shortly after treatment may add predictive power as they reflect additional factors including effective cellular exposure and the rate of DNAm recovery between treatment cycles. To determine if DNAm profiling at baseline and early during treatment can improve our ability to predict response, we examined targeted DNAm profiles in samples from patients with higher-risk MDS (HR-MDS), chronic myelomonocytic leukemia (CMML), and low-blast count acute myeloid leukemia (LB-AML), previously untreated with HMA who were enrolled in the Pevonedistat-2001 (P-2001) Phase 2 study of azacitidine (AZA) with or without pevonedistat (PEV). Methods: Targeted DNAm was quantified using bisulfite padlock probes (BSPP) at ~141,000 unique regions known to contain differentially methylated CpG sites. BSPP sequencing was performed on 130 genetically and clinically annotated bone marrow mononuclear cell DNA samples collected at screening and Cycle 2 Day 22±3 (C2D22). Data from 15 samples were removed due to low CpG coverage resulting in 115 samples with 〉10X coverage of 322,387 CpGs each. There were 27 patients with paired samples, 30 with screening only, and 31 with C2D22 only (Table 1, Figure 1A). Responses for HR-MDS and CMML were categorized according to the IWG-2006 modified criteria and for LB-AML according to the IWG-2003 criteria. Differentially methylated CpGs were identified using the R package 'DSS' v2.35.0. Non-negative matrix factorization-based unsupervised clustering was performed using the Onco-GPS method within the Python 'ccal' package. Statistical analyses were carried out using R version 3.6.2. Results: Differential DNAm analysis between screening and C2D22 for the 27 paired samples shows global demethylation after treatment in nearly all cases but is more pronounced in responders (mean change in global DNAm: response = -5.5%; non-response = -2.0%; t-test p 〈 0.001). There was no significant difference in demethylation between AZA and AZA+PEV treated groups (AZA: -5.3%; AZA+PEV: -4.1%; t-test p = 0.32). Patients who attained a complete response (CR) in the AZA+PEV arm tended to have more demethylated CpGs than those with a CR in the AZA arm (Figure 1B. Mean number of demethylated CpGs in complete responders: AZA = 16,459; AZA+PEV = 24,731; t-test p = 0.396). In general, responding patients strictly defined by CR or partial response had steeper declines in mean DNAm levels (Figure 1C) than patients with other types of responses, but did not show an association between demethylation and time to response (TTR). Unsupervised clustering of the top 3% most variably methylated CpGs using Onco-GPS did not identify clusters associated with response at screening, but did resolve a cluster highly enriched for responders assessed at C2D22 (Figure 1D. Cluster B, Fisher's exact test p = 0.011; odds-ratio 95% CI = 1.52-Inf). Analysis of the CpG sites that define Cluster B and creation of a formalized statistical predictor of response based on DNAm patterns is ongoing. Conclusions: DNAm patterns early in the course of HMA treatment correlate with eventual response, with CRs associated with the greatest degree of demethylation. Responders are more likely to have greater demethylation that may reflect greater effective AZA exposure or slower remethylation dynamics. Addition of PEV may intensify site-specific demethylation in responders and increase the proportion of responding patients. With a median TTR of 3-4 months in the P-2001 study, depth of demethylation at the C2D22 timepoint may help predict eventual response. Strategies to augment demethylation with adjunctive agents or HMA dose escalation in patients with early inadequate demethylation should be investigated. Ongoing work will incorporate mutation status and focus on refining DNAm signatures that can predict eventual response. Disclosures Luger: Arcturus Therapeutics: Current Employment. Zhao:Millennium Pharmaceuticals Inc., a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Current Employment. Fram:Takeda, Bristol Myers, Gilead, Pfizer, Baxter, Teva: Current equity holder in publicly-traded company; BeyondSpring Pharmaceuticals Inc.: Consultancy; Takeda Pharmaceuticals Intl. Co.: Current Employment; Vertex Pharmaceuticals: Patents & Royalties: No Royalties; Patent 10/728,114 (Vertex Pharmaceuticals). Dash:Millennium Pharmaceuticals, Inc., a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Current Employment, Other: Stockholder. Bejar:Forty-Seven/Gilead: Honoraria; Genoptix/NeoGenomics: Honoraria; Daiichi-Sankyo: Honoraria; Takeda: Honoraria, Research Funding; Celgene/BMS: Honoraria, Research Funding; Astex/Otsuka: Honoraria; AbbVie/Genentech: Honoraria; Aptose Biosciences: Current Employment.

Beschreibung: Background: With the rapid decline of sequencing costs and the introduction of next-generation sequencing (NGS) instruments with higher processing capacity, the rate-limiting step in reporting genetic test results is moving away from sequencing production towards data interpretation. Powerful bioinformatics tools have been created to address this bottleneck. Though substantial advances have been made in clinical variant classification, much work remains. This is particularly true in the evaluation of somatic variants, where there is currently a high degree of variability in how members of the global molecular genetics and pathology community establish and validate bioinformatics pipelines and apply classification guidelines, and in how results are reported to clinicians. Aim: Create a reliable and widely available resource for variants relevant for hematologic malignancies and make their classification readily accessible to the wider hematology community, facilitating NGS diagnostics and improve the consistency and robustness of testing results to improve patient care . Methods: The ASH Somatic Working Group (SWG) is comprised of hematologists, hematopathologists, molecular biologists and bioinformaticians. The group was formed under the auspices of ASH two years ago to improve clarity around the various gene panels being used in our community and in the reporting of genetic variants associated with hematologic malignancies. The group collected 1) the list of genes (i.e. entity-specific panels) that are typically used in research or clinical laboratory applications at 8 different and specialized laboratories; 2) the variants within those genes and their respective internally developed tiering and interpretations among 6 laboratories; and 3) the institutional bioinformatics pipelines used for those interpretations. The working group identified 70 genes most commonly used in assays for myeloid and lymphoid diseases. A three-class system for defining somatic pathogenicity was used, to unify the submissions from 6 institutions. Pathogenic variants are those that have been clearly determined to be associated with tumorigenesis . Variants of unknown significance (VUS) may have evidence supporting or refuting their effect on somatic pathogenicity, but this evidence is not yet strong enough to classify the variants as pathogenic or benign. Benign variants have been determined not to drive tumorigenesis and are typically polymorphisms that are present throughout the (healthy) population at variable frequency. Individual variant assessment was performed by the contributing institutions using a variety of resources, including ClinVar, COSMIC, cBioPortal/OnkoKB, St. Jude PCGP, ARUP, LOVD, dbSNP and IARC databases, as well as population frequency information from gnomAD/ExAC and in-silico mutation impact prediction tools included SIFT, PolyPhen2, Mutation assessor, LRT, FATHMM, CADD, REVEL and dbNSFP. Additionally, evidence was uncovered through manual literature review. Results: Through an iterative process, the SWG has initially identified 202 variants of high confidence (with highly concordant interpretation amongst contributing laboratories) in 42 of 70 genes. These results will be publicly available as both as a multi-institutional collaborative manuscript on best practices in this field as well as a searchable web application on the ASH web site (www.hematology.org/research) to aid other clinicians and investigators. On this website variants can be queried using genomic coordinates based on hg19, GRCh38 or Gene and HGVSc nomenclature. With the ongoing process of resolving remaining discrepancies, the high-confidence data will be updated regularly, with evidence provided to support classification. Conclusions: ASH has created an application to serve as a resource for NGS diagnostics based on a systematic review process, which we anticipate will lead to more consistency in molecular testing reports for patients undergoing evaluation of myeloid and lymphoid malignancies. Regular updates will help hematology professionals to use NGS in routine patient care on an ongoing basis. Disclosures Wagner: Nationwide Children´s Hospital: Current Employment. Bejar:Genoptix/NeoGenomics: Honoraria; Forty-Seven/Gilead: Honoraria; Daiichi-Sankyo: Honoraria; Celgene/BMS: Honoraria, Research Funding; Takeda: Honoraria, Research Funding; Astex/Otsuka: Honoraria; AbbVie/Genentech: Honoraria; Aptose Biosciences: Current Employment. Ewalt:University of Colorado: Current Employment; Memorial Sloan Kettering Cancer Center: Current Employment. Kim:Brigham and Women´s Hospital: Current Employment. Le Beau:Varian Medical Systems: Membership on an entity's Board of Directors or advisory committees; American Cancer Society: Membership on an entity's Board of Directors or advisory committees. Shammo:Onconova: Research Funding; Abbive: Current equity holder in publicly-traded company; Sanofi: Speakers Bureau; Takeda: Current equity holder in publicly-traded company; Agios: Consultancy; Novartis: Consultancy; Regeneron: Consultancy; BMS: Consultancy, Research Funding, Speakers Bureau; Celgene: Consultancy, Research Funding, Speakers Bureau; Apellis: Consultancy; Incyte: Consultancy, Research Funding, Speakers Bureau; Baxter: Current equity holder in publicly-traded company; Alexion: Consultancy, Research Funding, Speakers Bureau. Ryan:American Society of Hematology: Current Employment. Steensma:Aprea Therapeutics: Research Funding; Arrowhead Pharmaceuticals: Current equity holder in publicly-traded company; Astex Pharmaceuticals, Otsuka: Consultancy; H3 Biosciences: Research Funding; Takeda: Consultancy; BMS/Celgene: Consultancy; Onconova: Consultancy; Arena: Current equity holder in publicly-traded company; CRISPR: Current equity holder in publicly-traded company. Zehir:Memorial Sloan Kettering Cancer Center: Current Employment; Illumina: Honoraria.