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Epstein-Barr virus (EBV) is associated with hematologic and solid tumors. In this study, we utilized a hybridization capture-based next generation sequencing (NGS) platform that targets 400 genes associated with hematological malignancies to detect and quantify non-targeted viral-derived EBV reads that aligned to the EBV reference contig (NC_007605). We evaluated 5,234 samples from 3,636 unique patients with hematological neoplasms and found that 100 samples (1.9%) in 93 unique patients had ≥ 6 EBV reads (range, 6-32,325; mean, 827.5; median, 54). The majority (n=73, 73%) represented known EBV-associated conditions, and the most common was post-transplant lymphoproliferative disorders (n=21, 29%). Documented EBV viremia accounted for a moderate quantity of EBV reads in 4/27 samples corresponding to conditions not known to be EBV-associated, while suspected viremia or low-level activation was likely the etiology in the remaining 23 samples. A good correlation (Spearman r=0.8, 95% CI 0.74-0.85) was found between EBV reads by NGS and systematic semi-quantitative EBER ISH assessment in 162 available samples, particularly at higher level of EBV-involvement. An optimal threshold for significant morphologic EBV-involvement was found to be ≥10 reads by the receiver operating characteristic (ROC) analysis (AUC 0.990 and 95% CI 0.9974-1.000%). Thus, in addition to mutational analysis, hybrid-capture-based NGS panels can be used to detect and quantitate off-target EBV-derived viral DNA, which correlates well with morphology.

Patients treated with cytotoxic therapies, including autologous stem cell transplantation, are at risk for developing therapy-related myeloid neoplasms (tMN). Pre-leukemic clones (i.e., clonal hematopoiesis; CH) are detectable years before the development of these aggressive malignancies, though the genomic events leading to transformation and expansion are not well-defined. Here, leveraging distinctive chemotherapy-associated mutational signatures from whole-genome sequencing data and targeted sequencing of pre-chemotherapy samples, we reconstruct the evolutionary life-history of 39 therapy-related myeloid malignancies. A dichotomy is revealed, in which neoplasms with evidence of chemotherapy-induced mutagenesis from platinum and melphalan are hypermutated and enriched for complex structural variants (i.e., chromothripsis) while neoplasms with non-mutagenic chemotherapy exposures are genomically similar to de novo acute myeloid leukemia. Using chemotherapy-associated mutational signatures as temporal barcodes linked to a discrete clinical exposure in each patient's life, we estimate that several complex events and genomic drivers are acquired after chemotherapy is administered. For patients with prior multiple myeloma who were treated with high-dose melphalan and autologous stem cell transplantation, we demonstrate that tMN can develop from either a reinfused CH clone that escapes melphalan exposure and is selected following reinfusion, or from TP53-mutant CH that survives direct myeloablative conditioning and acquires melphalan-induced DNA-damage. Overall, we reveal a novel mode of tMN progression that is not reliant on direct mutagenesis or even exposure to chemotherapy. Conversely, for tMN that evolve under the influence of chemotherapy-induced mutagenesis, distinct chemotherapies not only select pre-existing CH, but also promote the acquisition of recurrent genomic drivers.

Introduction: Older adults with hematologic malignancies such as AML and MDS increasingly undergo allogeneic hematopoietic cell transplantation (alloHCT). The impact of the aging host environment, especially cellular senescence, remains unexplored, however. Objectives: We hypothesize that pre-transplant senescence-associated secretary phenotype (SASP) is associated with alloHCT outcomes among older patients and tested it in this biomarker correlative study. Methods: We measured ten SASP-related cytokines (IFNγ, IL1β, IL2, IL4, IL6, IL8, IL10, IL12, IL13, and TNFα, and C-reactive protein (CRP) from pre-transplant plasma samples of 155 patients (>50 years) who had undergone alloHCT at MSKCC from 2011 to 2019 for acute leukemias and other myeloid malignancies. Expression of aging biomarker p16 was measured on a subset of patients by immunohistochemistry. Results and Discussion: The median age was 64.1 years (IQR 58.3 – 67.8). Diseases included 57% acute leukemias (AML and ALL) and 43% MDS/MPN. KPS was 3 in 53% of patients. With median follow-up of 61 months for survivors, the 5-year OS and PFS is 50% and 46%, respectively. The 2-year cumulative incidence of non-relapse mortality (NRM) and relapse is 18% and 31%, respectively. At the baseline, these SASP-related cytokines have variable degree of association with KPS, chronologic age, and disease risk. IL2 trended toward significant positive association with OS (HR 1.19, 95% CI 1-1.43, p=0.052) and was significantly associated with PFS (HR 1.21, 95% CI 1.02-1.44, p=0025) in univariate analysis, but not in multivariate analysis after adjusting for clinical characteristics. No cytokine was associated with NRM. IL2 and IL4 were associated with relapse in univariate but not multivariate analysis. Several cytokines including IL12 p70, IL13, IL4, and TNFα were associated with 100d grade II-IV acute GVHD in patients who received CNI-based GVHD prophylaxis. In summary, we found potential association of SASP-related cytokines with patient characteristics and transplant outcomes. We aim to validate these findings and examine their therapeutic potential to improve alloHCT outcomes. Citation Format: Richard J Lin, Phillip Wong, Jessica R Flynn, Erika R Ritter, Caleb Ho, Josel D Ruiz, Ann A Jakubowski, Esperanza B Papadopoulos, Brian C Shaffer, Hugo R Castro-Malaspina, Christina J Cho, Doris R Ponce, Juliet N Barker, Roni Tamari, Craig S Sauter, Boglarka Gyurkocza, Marcel van den Brink, James W Young, Miguel-Angel Perales, Sean M Devlin, Sergio A Giralt. Aging-related, Senescence-associated Secretory Phenotype and Allogeneic Hematopoietic Cell Transplantation Outcomes in Older Adults [abstract]. In: Proceedings of the AACR Special Conference: Acute Myeloid Leukemia and Myelodysplastic Syndrome; 2023 Jan 23-25; Austin, TX. Philadelphia (PA): AACR; Blood Cancer Discov 2023;4(3_Suppl):Abstract nr A48.

The 2016 International Myeloma Working Group consensus recommendations emphasize high-sensitivity methods for minimal residual disease (MRD) detection, treatment response assessment, and prognostication. Next-generation sequencing (NGS) of IGH gene rearrangements is highly specific and sensitive, but its description in routine clinical practice and performance comparison with high-sensitivity flow cytometry (hsFC) remain limited. In this large, single-institution study including 438 samples from 251 patients, the use of NGS targeting the IGH and IGK genes for clonal characterization and monitoring, with comparison to hsFC, is described. The index clone characterization success rate was 93.6% (235/251), which depended on plasma cell (PC) cellularity, reaching 98% when PC ≥10% and below 80% when PC

Patients treated with cytotoxic therapies, including autologous stem cell transplantation, are at risk for developing therapy-related myeloid neoplasms1, 2. Pre-leukemic clones (i.e., clonal hematopoiesis) are detectable years before the development of these aggressive malignancies3-5, though the genomic events leading to transformation and expansion are not well-defined. Here, leveraging distinctive chemotherapy-associated mutational signatures6-12 from whole-genome sequencing data and targeted sequencing of pre-chemotherapy samples, we reconstruct the evolutionary life-history of 39 therapy-related myeloid malignancies. A dichotomy is revealed, in which neoplasms with evidence of chemotherapy-induced mutagenesis from platinum and melphalan are relatively hypermutated and enriched for complex structural variants (i.e., chromothripsis), while neoplasms with alternative exposures bear a similar profile to de novo acute myeloid leukemia. Using chemotherapy-associated mutational signatures as a temporal barcode in each patient’s life, we estimate that several complex events and genomic drivers are acquired after chemotherapy exposure. In the case of treatment with high-dose melphalan and autologous stem cell transplantation, we demonstrate that the procedure allows clonal hematopoiesis to escape chemotherapy exposure entirely, and to be reinfused to expand to malignancy. This information reveals a novel mode of malignant progression for therapy-related malignancies that is not reliant on direct mutagenesis or even exposure to chemotherapy, itself, and prompts further investigation into leukemia-permissive effects of cytotoxic drugs.

The prognosis of patients with relapsed or refractory (R/R) diffuse large B-cell lymphoma (DLBCL) is poor. Chimeric antigen receptor (CAR) T-cell therapy has been approved for R/R DLBCL after 2 prior lines of therapy based on data from single-arm phase 2 trials, with complete responses (CRs) in 40% to 60% of patients. However, a direct comparison with other treatments is not available and, moreover, its true efficacy in real-world patients is unknown. In this single center, retrospective, observational study of 215 patients, we compared outcomes in patients treated with CAR T-cell therapy (n = 69) with a historical population treated with alternate therapies (n = 146). Patients treated with CAR T cell vs alternate therapies demonstrated a CR rate of 52% vs 22% (P < .001), median progression-free survival (PFS) of 5.2 vs 2.3 months (P = .01), and median overall survival (OS) of 19.3 vs 6.5 months (P = .006), and this advantage appeared to persist irrespective of the number of lines of prior therapy. After adjusting for unfavorable pretreatment disease characteristics, superior overall response rate in the CAR T cohort remained significant; however, differences in PFS and OS between cohorts did not. In addition, patients who responded to alternate therapies demonstrated prolonged remissions comparable to those who responded to CAR T therapy. We contend that in select clinical scenarios alternate therapies may be as efficacious as CAR T therapy; thus, additional study is warranted, ideally with randomized prospective trials.

Minimal residual disease (MRD) tracking, by next generation sequencing of immunoglobulin sequences, is moving towards clinical implementation in multiple myeloma. However, there is only sparse information available to address whether clonal sequences remain stable for tracking over time, and to what extent light chain sequences are sufficiently unique for tracking. Here, we analyzed immunoglobulin repertoires from 905 plasma cell myeloma and healthy control samples, focusing on the third complementarity determining region (CDR3). Clonal heavy and/or light chain expression was identified in all patients at baseline, with one or more subclones related to the main clone in 3.2%. In 45 patients with 101 sequential samples, the dominant clonal CDR3 sequences remained identical over time, despite differential clonal evolution by whole exome sequencing in 49% of patients. The low frequency of subclonal CDR3 variants, and absence of evolution over time in active multiple myeloma, indicates that tumor cells at this stage are not under selective pressure to undergo antibody affinity maturation. Next, we establish somatic hypermutation and non-templated insertions as the most important determinants of light chain clonal uniqueness, identifying a potentially trackable sequence in the majority of patients. Taken together, we show that dominant clonal sequences identified at baseline are reliable biomarkers for long-term tracking of the malignant clone, including both IGH and the majority of light chain clones.

Approximately 15% of chronic lymphocytic leukemia/small lymphocytic lymphomas (CLL/SLL) transform into aggressive lymphomas, often diffuse large B cell lymphomas (DLBCL), known as Richter Syndrome ...

We present a novel approach for identifying approximate role-symmetric Nash equilibria in large simulation-based games. Our method uses neural networks to learn a mapping from mixed-strategy profiles to deviation payoffs—the expected values of playing pure-strategy deviations from those profiles. This learning can generalize from data about a tiny fraction of a game’s outcomes, permitting tractable analysis of exponentially large normal-form games. We give a procedure for iteratively refining the learned model with new data produced by sampling in the neighborhood of each candidate Nash equilibrium. Relative to the existing state of the art, deviation payoff learning dramatically simplifies the task of computing equilibria and more effectively addresses player asymmetries. We demonstrate empirically that deviation payoff learning identifies better approximate equilibria than previous methods and can handle more difficult settings, including games with many more players, strategies, and roles.

NPM1-mutated myeloid neoplasms (NPM1 + MNs) with

Background Lenalidomide maintenance improves progression-free survival for patients with multiple myeloma, although its optimal duration is unknown. Clearance of minimal residual disease (MRD) in the bone marrow results in superior outcomes, although its attainment or sustainment does not alter clinical decision-making. Studies that have evaluated MRD serially are limited in length. We therefore aimed to evaluate longitudinal changes in MRD-status (dynamics) and their association with progression-free survival in patients with multiple myeloma.In this single-centre, single-arm, phase 2 study, we enrolled patients aged 18 years and older from the Memorial Sloan Kettering Cancer Center (New York, NY, USA) who had newly diagnosed multiple myeloma following unrestricted frontline therapy and an Eastern Cooperative Oncology Group Performance Status of 2 or lower, including patients who started maintenance before study enrolment. All participants received lenalidomide maintenance at 10 mg for 21 days of 28-day cycles until progression or unacceptable toxic effects for up to 5 years on protocol. The primary endpoint was progression-free survival at 60 months per protocol and key secondary endpoints were MRD rates after completion of the 12th, 24th, and 36th cycle of maintenance and the association between progression-free survival and annual measurement of MRD status. MRD was assessed from first-pull bone marrow aspirates at baseline and annually by flow cytometry per International Myeloma Working Group criteria, (limit of detection of at least 1 × 10Between Sept 8, 2015, and Jan 25, 2019, 108 patients (100 evaluable for the primary endpoint) were enrolled. Median follow-up was 40·7 months (95% CI 38·7-45·0). At 60 months, progression-free survival was 64% (95% CI 52-79). Median progression-free survival was unreached (95% CI unreached-unreached). MRD dynamics were assessed using 340 MRD assessments done over 5 years for 103 evaluable patients. Patients who sustained MRD negativity for 2 years (n=34) had no recorded disease progression at median 19·8 months (95% CI 15·8-22·3) past the 2-year maintenance landmark. By contrast, patients who lost their MRD-negative responses (n=10) were more likely to progress than those with sustained MRD negativity (HR infinite; p0·0001) and those with persistent MRD positivity (HR 5·88, 95% CI 1·18-33·33; p=0·015) at the 2-year landmark. Haematological and non-haematological serious adverse events occurred in 19 patients (18%). The most common adverse events of grade 3 or worse were decreased lymphocyte count in 48 (44%) patients and decreased neutrophil count in 47 (44%) patients. One death occurred on study due to sepsis and heart failure and was considered unrelated to the study drug.Serial measurements of MRD allow for dynamic assessment of risk for disease progression. Early intervention should be investigated for patients with loss of MRD negativity. Sustained MRD positivity is not categorically an unfavourable outcome and might portend prolonged stability of low-level disease.Memorial Sloan Kettering and Celgene.

Breast implant associated anaplastic large cell lymphoma (BIA-ALCL) is a distinct type of ALCL, and a new provisional entity by the 2016 revision of the World Health Organization (WHO) classification of tumors of hematopoietic and lymphoid tissues. In contrast to systemic and primary cutaneous ALCLs, BIA-ALCLs have been genetically characterized by the absence of fusions and frequent activation of the JAK-STAT3 pathway through mutations in JAK1 and STAT3. In this study, we report the results of the genetic profiling of 9 BIA-ALCL cases supporting the role of the JAK-STAT pathway activation in this entity, including the identification of an activating STAT3-JAK2 fusion similar to those recently reported in T-cell lymphoproliferative disorders of the gastrointestinal tract. To our knowledge, this is the first fusion reported in BIA-ALCL, providing further insight into the overall genetic landscape of this rare entity as well as uncovering potential options for targeted therapy in cases with advanced disease.

For patients diagnosed with multiple myeloma (MM) there have been significant treatment advances over the past decade, reflected in an increasing proportion of patients achieving durable remissions. Clinical trials repeatedly demonstrate that achieving a deep response to therapy, with a bone marrow assessment proving negative for minimal residual disease (MRD), confers a significant survival advantage. To accurately assess for minute quantities of residual cancer requires highly sensitive methods; either multiparameter flow cytometry or next generation sequencing are currently recommended for MM response assessment. Under optimal conditions, these methods can detect one aberrant cell amongst 1,000,000 normal cells (a sensitivity of 10-6). Here, we will review the practical use of MRD assays in MM, including challenges in implementation for the routine diagnostic laboratory, standardisation across laboratories and clinical trials, the clinical integration of MRD status assessment into MM management and future directions for ongoing research.

Catalyst discovery and optimization is key to solving many societal and energy challenges including solar fuels synthesis, long-term energy storage, and renewable fertilizer production. Despite considerable effort by the catalysis community to apply machine learning models to the computational catalyst discovery process, it remains an open challenge to build models that can generalize across both elemental compositions of surfaces and adsorbate identity/configurations, perhaps because datasets have been smaller in catalysis than related fields. To address this we developed the OC20 dataset, consisting of 1,281,040 Density Functional Theory (DFT) relaxations (~264,890,000 single point evaluations) across a wide swath of materials, surfaces, and adsorbates (nitrogen, carbon, and oxygen chemistries). We supplemented this dataset with randomly perturbed structures, short timescale molecular dynamics, and electronic structure analyses. The dataset comprises three central tasks indicative of day-to-day catalyst modeling and comes with pre-defined train/validation/test splits to facilitate direct comparisons with future model development efforts. We applied three state-of-the-art graph neural network models (CGCNN, SchNet, Dimenet++) to each of these tasks as baseline demonstrations for the community to build on. In almost every task, no upper limit on model size was identified, suggesting that even larger models are likely to improve on initial results. The dataset and baseline models are both provided as open resources, as well as a public leader board to encourage community contributions to solve these important tasks., 37 pages, 11 figures, submitted to ACS Catalysis

In patients with multiple myeloma, plasmablastic transformation in the bone marrow is rare and associated with poor outcomes. The significance of discordant extramedullary plasmablastic transformation in patients with small, mature clonal plasma cells in the bone marrow has not been well studied. Here, we report the clinicopathologic, cytogenetic, and molecular features of 10 such patients (male/female: 6/4, median age: 65 y, range: 48 to 76 y) with an established diagnosis of multiple myeloma in the bone marrow composed of small, mature plasma cells in parallel with a concurrent or subsequent extramedullary plasmablastic transformation. Eight patients with available survival data showed an overall aggressive clinical course with a median survival of 4.5 months after the diagnosis of extramedullary plasmablastic transformation, despite aggressive treatment and even in patients with low-level bone marrow involvement. Pathologically, the extramedullary plasmablastic myeloma were clonally related to the corresponding bone marrow plasma cells, showed high levels of CMYC and/or P53 expression with a high Ki-67 proliferation index by immunohistochemistry and harbored more complex genomic aberrations including frequent mutations in the RAS pathway and MYC rearrangements compared with their bone marrow counterparts. In summary, although genetic and immunohistochemical studies were not uniformly performed on all cases due to the retrospective nature of this study, our data suggest that discordant extramedullary plasmablastic transformation of multiple myeloma has an aggressive clinical course and is characterized by frequent mutations in the RAS pathway and more complex genomic abnormalities.

No abstract available Keywords: AML; CTLA-4 antagonist; P2RY8-CRLF2 fusion; immunotherapy.

Integration of morphological, immunohistochemical, and molecular methods is often necessary for the precise diagnosis and optimal clinical management of sarcomas. We have validated and implemented a clinical molecular diagnostic assay, MSK- Fusion Solid, for detection of gene fusions in solid tumors, including sarcomas. Starting with RNA extracted from formalin-fixed paraffin-embedded tumor material, this targeted RNA sequencing assay utilizes anchored multiplex PCR to detect oncogenic fusion transcripts involving 62 genes known to be recurrently rearranged in solid tumors including sarcomas without prior knowledge of fusion partners. From 1/2016 to 1/2018, 192 bone and soft tissue tumors were submitted for MSK- Fusion Solid analysis and 96% (184/192) successfully passed all the pre-sequencing quality control parameters and sequencing steps. These sarcomas encompass 24 major tumor types, including 175 soft tissue tumors and 9 osteosarcomas. Ewing and Ewing-like sarcomas, rhabdomyosarcoma, and sarcoma-not otherwise specified were the three most common tumor types. Diagnostic in-frame fusion transcripts were detected in 43% of cases, including 3% (6/184) with novel fusion partners, specifically TRPS1-PLAG1, VCP-TFE3, MYLK-BRAF, FUS-TFCP2, and ACTB-FOSB, the latter in two cases of pseudomyogenic hemangioendothelioma, representing a novel observation in this sarcoma. Our experience shows that this targeted RNA sequencing assay performs in a robust and sensitive fashion on RNA extracted from most routine clinical specimens of sarcomas thereby facilitating precise diagnosis and providing opportunities for novel fusion partner discovery.

Background: Patients treated with cytotoxic chemotherapies and/or autologous stem-cell transplantation (ASCT) are at risk for therapy-related myeloid neoplasms (tMN). As these agents yield increased mutation burden in relapsed malignancies and leave evidence of exposure via mutational signatures, we studied the genomic and temporal relationship between chemo exposure and progression of clonal hematopoiesis (CH) to tMN. Methods: We analyzed 32 tMN whole genomes (WG) from 31 patients [27 acute myeloid leukemias (AML), 4 myelodysplastic syndromes]. For 7 patients with tMN post-high-dose melphalan/ASCT, we investigated the presence of antecedent CH using targeted sequencing (MSK-IMPACT; Bolton et al. Nat Gen 2020) on pre-melphalan blood mononuclear cells, granulocytes, or CD34+ apheresis samples. Results: TMN was diagnosed a median of 4.2 years (IQR, 2.6-6.6) following primary treatment. When compared to data from 200 de novo AML from TCGA (NEJM, 2013), tMNs had fewer mutations in FLT3 (9.7% v 28.0%; p = 0.028) and NPM1 (3.2% v 27.0%; p = 0.003). TP53 loss was enriched in tMNs (25.8% v 10.5%; p = 0.035 ). Mutational signature analysis revealed 5 known single base substitution (SBS) signatures in tMN: the hematopoietic stem-cell (SBS-HSC), aging (SBS1), melphalan (SBS-MM1), and platinum signatures (E-SBS1, E-SBS20) (Rustad et al. Nat Comm 2020, Pich et al. Nat Gen 2019). Complex structural variants (SV), defined as ≥3 breakpoint pairs involved in simultaneous copy number changes (Rustad et al. Blood Can Disc 2020), were observed in 7 tMNs; including chromothripsis in 6 tumors (19.4%), chromoplexy in 2 (6.5%), templated insertion in 1 (3.2%), and unspecified complex SV in 2 (6.5%). Chromothripsis has not been previously reported in de novo AML and, in 4 cases, involved chromosome 19 with hyper-amplification of the SMARCA4 locus (≥5 copies). CH variants that became clonal in tumor were seen in 5/7 pre-melphalan/ASCT samples and included mutations in TP53, RUNX1, NCOR1, NF1, CREBBP, DNMT3A, and PPM1D. Chemotherapy introduces hundreds of mutations, leaving each exposed cell with a unique catalogue (i.e., barcode). In fact, TMNs with evidence of chemo signatures had a higher mutation burden (median 1574 single nucleotide variants) than those without (median 938; p = 0.004). Detection of chemo signatures in bulk genome sequencing relies on one cell, with its catalogue of mutations, to expand to clonal dominance (Fig 1a, Landau et al. Nat Comm 2020). Given the long latency between exposure and tMN diagnosis, this single-cell expansion model was expected for all samples exposed to melphalan or platinum-based regimens (i.e., agents with a measurable signature). Strikingly, all patients with pre-tMN platinum exposure (n=7) had evidence of platinum SBS signatures whereas only 2 of 7 patients with prior melphalan/ASCT had a melphalan signature (SBS-MM1). As all platinum-exposed tMN had mutational evidence of exposure, a CH clone must have existed prior to exposure, supporting a single-cell expansion model. Absence of a chemo signature for 5/7 post-melphalan/ASCT tumors despite exposure implies tumor progression driven either by multiple clones in parallel (Fig 1b) or by an unexposed clone. As latency largely excludes the former, this suggests pre-tMN CH clones were re-infused during SCT, thus avoiding chemo exposure (Fig 1c). This is supported by two lines of evidence: 1) tMNs from 2 patients exposed to sequential platinum and melphalan/ASCT had platinum but not melphalan signatures confirming single-cell expansion of the pre-tMN CH clone post-platinum but with escape from exposure to melphalan in the ASCT (Fig 1d); 2) targeted sequencing of pre-tMN samples from melphalan/ASCT patients identified tMN genomic mutations at the CH level in 5/7 cases, including in all 3 tested apheresis samples - one of which (TP53) expanded to dominance without a melphalan signature. Conclusion: WG sequencing identified novel features of tMN revealing the key driver role of complex SV. Mutational signature analyses and targeted sequencing of pre-tMN samples can increase our understanding of tMN pathogenesis and demonstrate that tMNs arising post-ASCT are often driven by CH clones that re-engraft after escaping melphalan exposure. This mode of expansion suggests that a permissive, immunosuppressed, post-transplant environment might play a more important role than chemotherapy-induced mutagenesis in tMN pathogenesis. Figure 1 Figure 1. Disclosures Diamond: Sanofi: Honoraria; Medscape: Honoraria. Watts: Rafael Pharmaceuticals: Consultancy; Genentech: Consultancy; Bristol Myers Squibb: Consultancy; Takeda: Consultancy, Research Funding; Jazz Pharmaceuticals: Consultancy; Aptevo Therapeutices: Research Funding. Kazandjian: Arcellx: Honoraria, Membership on an entity's Board of Directors or advisory committees; BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees. Bradley: AbbVie: Consultancy, Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Bolli: Amgen: Honoraria; Takeda: Honoraria; Janssen: Consultancy, Honoraria; Celgene/BMS: Consultancy, Honoraria. Papaemmanuil: Isabl Technologies: Divested equity in a private or publicly-traded company in the past 24 months; Kyowa Hakko Kirin Pharma: Consultancy. Scordo: Kite - A Gilead Company: Membership on an entity's Board of Directors or advisory committees; i3 Health: Other: Speaker; Omeros Corporation: Consultancy; Angiocrine Bioscience: Consultancy, Research Funding; McKinsey & Company: Consultancy. Lahoud: MorphoSys: Membership on an entity's Board of Directors or advisory committees. Stein: Jazz Pharmaceuticals: Consultancy; Foghorn Therapeutics: Consultancy; Blueprint Medicines: Consultancy; Gilead Sciences, Inc.: Consultancy; Abbvie: Consultancy; Janssen Pharmaceuticals: Consultancy; Genentech: Consultancy; Celgene: Consultancy; Bristol Myers Squibb: Consultancy; Agios Pharmaceuticals, Inc: Consultancy; Novartis: Consultancy; Astellas: Consultancy; Syndax Pharmaceuticals: Consultancy; PinotBio: Consultancy; Daiichi Sankyo: Consultancy; Syros Pharmaceuticals, Inc.: Consultancy. Sauter: Precision Biosciences: Consultancy; Kite/Gilead: Consultancy; Bristol-Myers Squibb: Research Funding; GSK: Consultancy; Gamida Cell: Consultancy; Celgene: Consultancy, Research Funding; Genmab: Consultancy; Novartis: Consultancy; Spectrum Pharmaceuticals: Consultancy; Juno Therapeutics: Consultancy, Research Funding; Sanofi-Genzyme: Consultancy, Research Funding. Hassoun: Celgene, Takeda, Janssen: Research Funding. Mailankody: Bristol Myers Squibb/Juno: Research Funding; Physician Education Resource: Honoraria; Plexus Communications: Honoraria; Takeda Oncology: Research Funding; Jansen Oncology: Research Funding; Fate Therapeutics: Research Funding; Allogene Therapeutics: Research Funding; Legend Biotech: Consultancy; Evicore: Consultancy. Korde: Medimmune: Membership on an entity's Board of Directors or advisory committees; Amgen: Research Funding. Hultcrantz: Daiichi Sankyo: Research Funding; Intellisphere LLC: Consultancy; Curio Science LLC: Consultancy; GlaxoSmithKline: Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Research Funding. Shah: Bristol Myers Squibb: Research Funding; Janssen: Research Funding. Shah: Janssen Pharmaceutica: Research Funding; Amgen: Research Funding. Park: Servier: Consultancy; Affyimmune: Consultancy; Autolus: Consultancy; Minerva: Consultancy; PrecisionBio: Consultancy; BMS: Consultancy; Novartis: Consultancy; Kura Oncology: Consultancy; Curocel: Consultancy; Artiva: Consultancy; Innate Pharma: Consultancy; Intellia: Consultancy; Amgen: Consultancy; Kite Pharma: Consultancy. Landau: Genzyme: Honoraria; Takeda, Janssen, Caelum Biosciences, Celgene, Pfizer, Genzyme: Membership on an entity's Board of Directors or advisory committees; Takeda: Research Funding. Sekeres: BMS: Membership on an entity's Board of Directors or advisory committees; Takeda/Millenium: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees. Ho: Blueprint Medicine: Membership on an entity's Board of Directors or advisory committees. Roshal: Celgene: Other: Provision of services; Auron Therapeutics: Other: Ownership / Equity interests; Provision of services; Physicians' Education Resource: Other: Provision of services. Lesokhin: pfizer: Consultancy, Research Funding; Janssen: Honoraria, Research Funding; Iteos: Consultancy; Serametrix, Inc: Patents & Royalties; Genetech: Research Funding; Trillium Therapeutics: Consultancy; bristol myers squibb: Research Funding; Behringer Ingelheim: Honoraria. Morgan: BMS: Membership on an entity's Board of Directors or advisory committees; Jansen: Membership on an entity's Board of Directors or advisory committees; Karyopharm: Membership on an entity's Board of Directors or advisory committees; Oncopeptides: Membership on an entity's Board of Directors or advisory committees; GSK: Membership on an entity's Board of Directors or advisory committees. Landgren: Janssen: Other: IDMC; Janssen: Research Funding; Amgen: Honoraria; Celgene: Research Funding; Janssen: Honoraria; Amgen: Research Funding; Takeda: Other: IDMC; GSK: Honoraria. Maura: OncLive: Honoraria; Medscape: Consultancy, Honoraria.

Background: TP53 mutant mantle cell lymphoma (MCL) is associated with poor survival outcomes with chemoimmunotherapy (Eskelund Blood 2017) and there is no standard frontline treatment for this high-risk patient population. The combination of Bruton's Tyrosine Kinase (BTK) inhibition and the BCL2 inhibition have been shown to be synergistic and active in relapsed, refractory MCL, including in patients with TP53 mutation (Tam NEJM 2018). Obinutuzumab, ibrutinib, and venetoclax has been shown to be well tolerated and associated with high response rates in relapsed and untreated MCL patients (Le Gouill Blood 2021). We hypothesize that treatment with zanubrutinib (B; BGB-3111; BTK inhibitor), obinutuzumab (O; CD20 antibody), and venetoclax (Ven; BCL2 inhibitor) (BOVen) will be well tolerated and efficacious in untreated TP53 mutant MCL. Methods: In this multicenter, investigator-initiated phase 2 trial (NCT03824483), eligible pts had previously untreated MCL with TP53 mutation (any variant allele frequency allowed) and ECOG PS1, PLT >75, HGB >=9 (unless if due to MCL). BOVen is administered in 28D cycles: B 160 mg PO BID starting D1; O 1000 mg IV D1 or split D1-2, 8, 15 of C1, D1 of C2-8; Ven ramp up initiated C3D1 (target 400 mg QD). Tx duration is 2 years at minimum and primary endpoint is 2-year progression-free survival. Adverse events (AE) were assessed per CTCAE v5. Results: 12 patients have been enrolled of the 25 total planned accrual. The median age on study was 67.5 years (range 29 - 79); 83% were male (10/12); various histologic subtypes were included (9 conventional MCL, 2 non-nodal leukemic, and 1 blastoid variant); 100% stage IV (12/12); by MIPI: 75% high risk (9/12), 17% intermediate (2/12), and 8% low risk MIPI score (1/12); 90% Ki67 >=30% (n=9/10); 50% Ki67>=50% (n=5/10); and 50% 17p deletion (n=6/12). All 12 patients were evaluable for toxicity. The grade 3 treatment-related AEs were limited to infusion-related reaction (17%, n=2 pts), neutropenia (8%, n=1 pt) that resolved with GCSF support, and elevation of transaminases (8%, n=1 pt). The most common treatment-related AEs (occurred in more than 1 patient) were low-grade and included: infusion-related reaction (17%, grade 1-2, n=3), neutropenia (17%, grade 1-2, n=2), thrombocytopenia (25%, grade 1, n=3), nausea (33%, grade 1, n=4), elevation of transaminases, (17%, grade 1, n=2), and rash (17%, grade 1, n=2). There was one treatment-related serious adverse event of fever without neutropenia that occurred on C3D2 after BOVen treatment. Pt was discharged after brief hospitalization in stable condition with resolution of fever and negative infectious work up. No dose reductions or modifications were required. No pts had laboratory/clinical TLS (Howard). Median follow up was 4 months (0 - 11 months). One pt has progressed and eleven pts remain on study in continued response. Of the 10 patients who have undergone disease restaging by Lugano criteria at C3 post BO, 80% (n=8/10) achieved PET-CR which has been maintained in 2 patients at C7. One patient, who has TP53, CARD11, and SMARCA4 mutations, achieved stable disease at C3, converted to a partial response at C7, and is now progressing during C12. The other patient had progressive disease by Lugano criteria at C3 with a mixed response on PET/CT with some sites of tumor regression, but after the addition of venetoclax pt had resolution of bulky palpable adenopathy and systemic symptoms. All patients had baseline positive peripheral blood flow cytometry (PBFC) and at C3 90% (n=9/10) had negative PBFC. Conclusions: BOVen was well tolerated in untreated TP53 mutant MCL. The preliminary efficacy is promising in this high-risk subset of MCL, however, follow-up is limited. Updated response data, including minimal residual disease assessment using a next-generation immunosequencing (IS) assay, will be presented at the meeting. Disclosures Kumar: Kite Pharmaceuticals: Other: advisory board , Research Funding; Celgene: Honoraria, Other: advisory board, Research Funding; Abbvie Pharmaceuticals: Research Funding; Seattle Genetics: Research Funding; Pharmacyclics: Research Funding; Adaptive Biotechnologies, Celgene, Abbvie Pharmaceticals, Pharmacyclics, Seattle Genetics: Research Funding; Astra Zeneca: Honoraria, Other: Advisory Board, Research Funding. Soumerai: AstraZeneca: Consultancy; Adaptive Biotechnologies: Consultancy, Research Funding; BeiGene: Consultancy, Research Funding; BMS: Consultancy; AbbVie: Consultancy; BostonGene: Research Funding; GlaxoSmithKline: Research Funding; Seattle Genetics: Consultancy; TG Therapeutics: Consultancy, Research Funding. Abramson: Morphosys: Consultancy; AbbVie: Consultancy; Novartis: Consultancy; EMD Serono: Consultancy; Kymera: Consultancy; Seagen Inc.: Research Funding; Allogene Therapeutics: Consultancy; BeiGene: Consultancy; Kite Pharma: Consultancy; C4 Therapeutics: Consultancy; Bristol-Myers Squibb Company: Consultancy, Research Funding; Bluebird Bio: Consultancy; Genmab: Consultancy; Incyte Corporation: Consultancy; Astra-Zeneca: Consultancy; Karyopharm: Consultancy; Genentech: Consultancy. Batlevi: Kite Pharma: Consultancy; TG Therapeutics: Consultancy; Viatris: Current holder of individual stocks in a privately-held company; Juno/Celgene: Consultancy; ADC Therapeutics: Consultancy; Seattle Genetics: Consultancy; Karyopharm: Consultancy; Medscape: Honoraria; BMS: Current holder of individual stocks in a privately-held company; Pfizer: Current holder of individual stocks in a privately-held company; Regeneron: Current holder of individual stocks in a privately-held company; Moderna: Current holder of individual stocks in a privately-held company; TouchIME: Honoraria; Dava Oncology: Honoraria; Life Sciences: Consultancy; Memorial Sloan Kettering Cancer Center: Current Employment; Bayer: Research Funding; GLG Pharma: Consultancy; Xynomic: Research Funding; Roche/Genentech: Research Funding; Novartis: Research Funding; Epizyme: Research Funding; Janssen: Research Funding; Autolus: Research Funding. Dogan: Takeda: Consultancy, Research Funding; Physicians' Education Resource: Honoraria; Peer View: Honoraria; Roche: Consultancy, Research Funding; EUSA Pharma: Consultancy; Seattle Genetics: Consultancy. Falchi: Roche: Research Funding; Genmab: Consultancy, Research Funding; Abbvie: Consultancy, Research Funding; Genetech: Research Funding. Ho: Blueprint Medicine: Membership on an entity's Board of Directors or advisory committees. Khan: Seattle Genetics: Research Funding. Matasar: IGM Biosciences: Research Funding; Merck: Consultancy; GlaxoSmithKline: Honoraria, Research Funding; Daiichi Sankyo: Consultancy; Genentech, Inc.: Consultancy, Honoraria, Research Funding; ImmunoVaccine Technologies: Consultancy, Honoraria, Research Funding; TG Therapeutics: Consultancy, Honoraria; Juno Therapeutics: Consultancy; Pharmacyclics: Honoraria, Research Funding; Rocket Medical: Consultancy, Research Funding; Memorial Sloan Kettering Cancer Center: Current Employment; Teva: Consultancy; Takeda: Consultancy, Honoraria; Merck Sharp & Dohme: Current holder of individual stocks in a privately-held company; Bayer: Consultancy, Honoraria, Research Funding; F. Hoffmann-La Roche Ltd: Consultancy, Honoraria, Research Funding; Janssen: Honoraria, Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding. Abdel-Wahab: Foundation Medicine Inc: Consultancy; Prelude Therapeutics: Consultancy; Merck: Consultancy; LOXO Oncology: Consultancy, Research Funding; H3B Biomedicine: Consultancy, Research Funding; Lilly: Consultancy; AIChemy: Current holder of stock options in a privately-held company, Membership on an entity's Board of Directors or advisory committees; Envisagenics Inc.: Current holder of stock options in a privately-held company, Membership on an entity's Board of Directors or advisory committees. Zelenetz: Gilead: Honoraria, Research Funding; MEI Pharma: Honoraria, Research Funding; AstraZeneca: Honoraria; Gilead: Honoraria; Janssen: Honoraria; Pharmacyclics: Honoraria; Amgen: Honoraria; Novartis: Honoraria; MorphoSys: Honoraria; Genentech/Roche: Honoraria, Research Funding; Verastem: Honoraria; Abbvie: Honoraria, Research Funding; BMS/Celgene/JUNO: Honoraria, Other; Beigene: Honoraria, Other, Research Funding; SecuraBio: Honoraria; LFR: Other; MethylGene: Research Funding; NCCN: Other.

Human papillomavirus (HPV)-negative cervical carcinomas are uncommon and typically encompass unusual histologic subtypes. Mesonephric adenocarcinoma is one such subtype. Mesonephric tumors in the female genital tract are thought to arise from Wolffian remnants, and are extremely rare tumors with widely variable morphology. Sarcomatoid dedifferentiation has been previously described in a few cases, but other forms of dedifferentiation have not been reported. Neuroendocrine carcinoma of the cervix (e.g. small cell carcinoma) is associated with HPV infection, typically HPV 18. These tumors often arise in association with a conventional epithelial component such as squamous cell carcinoma or usual-type endocervical adenocarcinoma. We describe a case of mesonephric adenocarcinoma of the uterine cervix associated with an HPV-negative high-grade neuroendocrine carcinoma at the morphologic and immunophenotypic level, for which we performed targeted massively parallel sequencing analysis of the two elements. Both components shared identical mutations in U2AF1 p.R156H (c.467G>A) and GATA3 p.M422fs (c.1263dupG), as well as MYCN amplification. In addition, the neuroendocrine carcinoma harbored TP53 and MST1R mutations not present in the mesonephric carcinoma. Our data suggest a clonal origin of the two components of this rare entity, rather than a collision tumor.

Background: Fit patients (pts) with mantle cell lymphoma (MCL) are commonly treated with immunochemotherapy and consolidative high-dose therapy + stem cell rescue (cHDT/SCR), yet this approach has not demonstrated an overall survival (OS) benefit in a randomized trial. Outcomes for pts with high-risk MCL (TP53 aberrancy, high proliferation index, blastic histology) after cHDT/SCR are poor, and not all pts with MCL are eligible for this approach. Methods: We conducted a phase II study of sequential immunochemotherapy incorporating lenalidomide enriching for pts with high-risk disease features (defined as blastoid/pleomorphic histology and/or Ki67 >=30%). The three phases of tx were: 1) lenalidomide (15 mg daily, days 1-14) plus R-CHOP for four 21-day cycles; 2) R-HiDAC for 2 cycles (initially age-based cytarabine 1-3 g/m2; 3 g/m2 dose removed after 16 pts due to hematologic toxicity); and 3) rituximab monthly plus lenalidomide (15 mg daily) for 6 months (mos). Eligibility requirements were untreated stage II-IV MCL, KPS ≥70%, and adequate organ function; we sought ≥2/3 high-risk pts. We performed MRD testing on peripheral blood (cellular DNA) using the clonoSEQ Assay (Adaptive Biotechnologies). We obtained PET/CT and MRD testing after each phase of treatment and also MRD evaluation at 6 mos post-rituximab + lenalidomide maintenance. The primary endpoint was the rate of 3-yr progression-free survival (PFS), (acceptable PFS ≥75%, unacceptable ≤60%, based on desired proportion of high-risk pts). Results: Among 49 pts enrolled, 47 were evaluable for PFS (1 had progressive disease (PD) and 1 had toxicity during len-R-CHOP). Characteristics for 47 evaluable pts are shown in Table 1: 64% were high-risk and 18% had TP53 mutation. 45 completed maintenance (1 had PD during R-HiDAC and 1 withdrew to pursue cHDT/SCR) and 43 achieved complete response (CR), 1 stable disease, and 1 PD at end of treatment (EoT), yielding overall response rate of 91%, all CR (Figure 1). With a median follow-up of 2.8 yrs among survivors, the 3-yr PFS was 64% (95 CI 50, 82) and OS 85% (95 CI 74, 99). Three-yr PFS differed by TP53 status (14% mut vs. 85% wt, P < 0.0001, Table 2). Of 4 pts with PD, 3 had TP53 mutation and 1 had an unknown mutation status. Among TP53 wt pts, there was no significant difference in outcomes by risk (Table 2). MRD results were not obtained in 4 pts. Among 45 pts with MRD results, tumor clonal characterization for MRD evaluation was successful in 87% (39/45). MRD results are shown in Figure 2. Examining the initial phase of treatment (len-R-CHOP and R-HiDAC), among 37 pts with results at 1x10-5 sensitivity (1E5) following len-RCHOP, a substantial proportion (32%, 12/37 pts) remained MRD+ and 11 of 12 MRD+ pts post len-RCHOP converted to MRD- following R-HiDAC. At 1x10-6 sensitivity (1E6) following R-HiDAC, 5/20 pts were MRD+, and among responding pts, shorter median PFS was observed in MRD+ versus MRD- pts (23.1 mos vs. NR, P = 0.03). Examining the final phase of treatment (rituximab + lenalidomide maintenance) and observation period, among 37 pts with MRD results at 1E5 at EoT, 4 were MRD+, 2 of which were simultaneous (within 2 weeks of testing) with relapse; the remaining two MRD+ pts had median PFS 4.9 mos versus 37.4 mos for the 32 non-relapsed MRD- pts (P < 0.001). At 1E6, 6 pts who were MRD- at EoT converted to MRD+ after 6 mos of observation. MRD status at 1E6 at 6-mos post-EOT correlated with PFS: among 20 non-relapsed pts (6 MRD+, 14 MRD-), median PFS was 30.8 mos for MRD- versus 13.2 mos for MRD+ (P = 0.02). Conclusions: In a novel approach of sequential immunochemotherapy plus lenalidomide enrolling majority high-risk pts, outcomes for TP53-mutant pts were poor and we did not reach our primary endpoint of 3-yr PFS ≥75%. Among TP53-wt pts, this treatment program was highly effective even among pts with elevated Ki-67 (>=30%) and was associated with a high response rate, a 3-yr rate of PFS of 85%, and a high rate of MRD- at EoT. A substantial proportion of pts converted to MRD- after receipt of R-HiDAC, highlighting the efficacy of cytarabine in MCL. There was a high rate of MRD- after induction chemoimmunotherapy (Len-R-CHOP + R-HiDAC) at 1E5 (97%) and at 1E6 (80%), and the latter predicted remission duration. Several pts converted from MRD- to MRD+ at 6-mos post-EOT and eventually relapsed, suggesting that a more prolonged period of maintenance may be beneficial. Finally, MRD at 1E6 at 6 mos following EoT predicted response duration. Disclosures Batlevi: Life Sci, GLG, Juno/Celgene, Seattle Genetics, Kite: Consultancy; Janssen, Novartis, Epizyme, Xynomics, Bayer, Autolus, Roche/Genentech: Research Funding. Dogan:National Cancer Institute: Research Funding; EUSA Pharma: Consultancy; Takeda: Consultancy; Seattle Genetics: Consultancy; Corvus Pharmaceuticals: Consultancy; Physicians Education Resource: Consultancy; Roche: Consultancy, Research Funding; AbbVie: Consultancy. Drullinsky:Novartis: Research Funding; Roche: Research Funding. Gerecitano:Janssen: Current Employment. Hamlin:Portola Pharmaceutics: Consultancy; J&J Pharmaceuticals: Research Funding; Juno Therapeutics: Consultancy; Celgene: Consultancy; Incyte: Research Funding; Molecular Templates: Research Funding; Portola: Research Funding; Karyopharm: Consultancy. Ho:Invivoscribe, Inc.: Honoraria. Jacob:Adaptive Biotechnologies: Current Employment, Current equity holder in publicly-traded company. Matasar:Rocket Medical: Consultancy, Research Funding; Seattle Genetics: Consultancy, Honoraria, Research Funding; Daiichi Sankyo: Consultancy; Takeda: Consultancy, Honoraria; GlaxoSmithKline: Honoraria, Research Funding; IGM Biosciences: Research Funding; Janssen: Honoraria, Research Funding; Pharmacyclics: Honoraria, Research Funding; Immunovaccine Technologies: Honoraria, Research Funding; Merck: Consultancy; Bayer: Consultancy, Honoraria, Research Funding; Juno Therapeutics: Consultancy; F. Hoffmann-La Roche Ltd: Consultancy, Honoraria, Research Funding; Teva: Consultancy; Genentech, Inc.: Consultancy, Honoraria, Research Funding. Moskowitz:Incyte: Research Funding; Imbrium Therapeutics, L.P.: Consultancy; Seattle Genetics: Consultancy; Miragen Therapeutics: Consultancy; Merck: Consultancy; Seattle Genetics: Research Funding; Bristol-Myers Squibb: Research Funding; Merck: Research Funding. Mullins:Adaptive Biotechnologies: Current Employment, Other: shareholder. Straus:Elsevier: Membership on an entity's Board of Directors or advisory committees, Other: CME writer; NY Lymphoma Rounds: Consultancy; Imedex, Inc.: Speakers Bureau; Karyopharm Therapeutics: Membership on an entity's Board of Directors or advisory committees; Targeted Oncology: Consultancy, Speakers Bureau; ASH: Other: Conference in December 2019 on HL to other physicians during ASH; Seattle Genetics: Consultancy, Membership on an entity's Board of Directors or advisory committees; OncLive: Speakers Bureau; Takeda Pharmaceuticals: Research Funding, Speakers Bureau. Younes:BioPath: Consultancy; Daiichi Sankyo: Consultancy; Takeda: Consultancy; Novartis: Consultancy; AstraZeneca: Current Employment; BMS: Consultancy; Curis: Consultancy; Epizyme: Consultancy; HCM: Consultancy; Janssen: Consultancy. Zelenetz:Amgen: Consultancy; Celgene: Research Funding; Genentech/Roche: Consultancy; Sandoz: Research Funding; Novartis: Consultancy; Janssen: Consultancy; Adaptive Biotechnology: Consultancy; Celgene: Consultancy; Gilead: Consultancy; BeiGene: Membership on an entity's Board of Directors or advisory committees; Gilead: Research Funding; MorphoSys: Research Funding; MEI Pharma: Research Funding; Roche: Research Funding. Kumar:Celgene: Honoraria, Other: Honoraria for Advisory Board; Astra Zeneca: Honoraria, Other: Honoraria for Advisory Board; Celgene: Research Funding; Pharmacyclics: Research Funding; Adaptive Biotechnologies,: Research Funding; AbbVie: Research Funding; Seattle Genetics: Research Funding; Kite Pharmaceuticals: Honoraria, Other: Honoraria for Advisory Board.

Background. Consensus from prior studies shows that the use of maintenance therapy after completion of combination therapy leads to longer progression-free survival (PFS) for patients with multiple myeloma with some studies showing an overall survival (OS) benefit. Currently, lenalidomide is the standard of care; however, there are limited published data on long-term use regarding ability to sustain minimal residual disease (MRD)-negativity and late toxicities. We were motivated to develop a study focusing on continuous, induction-agnostic lenalidomide maintenance with integration of clinical and correlative data. Here, we report formal results of this phase II study with focus on MRD dynamics and tolerability. Methods. This single arm, phase II trial enrolled 100 evaluable patients. Lenalidomide 10 mg is given days 1-21 on a 28-day cycle. Per protocol, patients underwent bone marrow biopsies and aspirates as well as PET/CT at baseline, annually, at progression/end of study; blood work was done every 3 months. The study was statistically powered for the primary endpoint of PFS at 36 months. Correlative assays included MRD testing (10-color single-tube flow cytometry and IGHV sequencing; sensitivity ≤10-5), genomic characterization of detectable disease, and profiling of the bone marrow microenvironment performed on serially banked samples. Results. 100 evaluable patients were enrolled (63% males) between September 2015 and January 2019. Baseline characteristics include median age 63 years (range 38-87 years) and median ECOG score 1 (range 0-1). Prior to enrollment, 22 (30%) patients had high-risk FISH/SNP signature defined as one or more of: 1q+, t(4;14), t(14;16), t(14;20), and 17p- and 48 patients had undergone autologous hematopoietic cell transplantation (AHCT). At abstract submission, median cycles delivered is 39 (range 9-62). 74% of patients have completed ³24 cycles and 55% have completed ³36 cycles. Overall PFS at 36 months was 77% (95% CI: 0.69-0.87) and PFS at 60 months was 63% (95% CI: 0.51-0.78). All patients had MRD testing at least once. 46% were MRD-negative at enrollment. 7 patients who were MRD+ at enrollment converted to MRD-negative. At median follow up 39.4 months (range 7-56 months), 20/100 patients (20%) have progressed. In consideration of the entire follow-up time from initial MRD-negativity, 44 (of 95 tested; 46%) and 37 (of 73 tested; 51%) achieved sustained MRD-negativity at 1 and 2 years, respectively. 22 patients were MRD-negative at 3 years (of 51 tested; 43%). Among those who sustained MRD-negativity for 2 years, with median follow-up of 19 months past the 2-year landmark analysis (max 120 months), there were no progression events. Age, induction regimen, and MRD status at enrollment were the only significant variables associated with PFS regardless of cytogenetic risk or transplant status. At 1 and 2-year landmark analysis, MRD-negativity superseded all else as the most significant factor associated with PFS with HR 0.06(p=0.0004) and HR 1/Inf (p=0.015), respectively. Toxicities (grade 3) included neutrophil count decrease (20%), hypertension (3%), diarrhea (3%), lung infection (2%), and maculo-papular rash (2%), and toxicities (grade 4) include sepsis (2%) and platelet count decrease (7%). The most common non-grade 3/4 toxicities were diarrhea (55%), fatigue (36%), and upper respiratory infection (30%). 7% developed a secondary malignancy on study: 3 adenocarcinoma, 1 squamous cell carcinoma, 1 CMML, 1 MDS, 1 ALL, and 1 glioblastoma. One evaluable patient required dose reduction due to toxicities/tolerability. Conclusions. This prospective study of continuous lenalidomide maintenance, agnostic to induction regimen or AHCT usage, was designed to evaluate the dynamics of MRD-negativity in relation to PFS. It expands on the importance of MRD as a predictor of outcome and illustrates how continuous maintenance therapy can deepen and sustain MRD-negative responses achieved with modern combination therapy. For this cohort, MRD-negativity at each landmark profoundly outweighed the impact of all other variates. Among those who had sustained MRD-negativity at 2 years (37% of the cohort), regardless of MRD status at enrollment, none have had progression events at median 43 months. Our results support cross-sectional MRD testing as a surrogate endpoint for drug approval, and the use of longitudinal MRD tracking in clinical management. Disclosures Korde: Amgen: Research Funding; Astra Zeneca: Other: Advisory Board. Lesokhin:Genentech: Research Funding; Janssen: Research Funding; GenMab: Consultancy, Honoraria; Juno: Consultancy, Honoraria; Takeda: Consultancy, Honoraria; Serametrix Inc.: Patents & Royalties; BMS: Consultancy, Honoraria, Research Funding. Smith:Precision Biosciences: Consultancy; Bristol Myers Squibb: Consultancy, Patents & Royalties, Research Funding; Fate Therapeutics: Consultancy. Shah:Physicians Education Resource: Honoraria; Celgene/BMS: Research Funding. Mailankody:Physician Education Resource: Honoraria; PleXus Communications: Honoraria; Takeda Oncology: Research Funding; Janssen Oncology: Research Funding; Allogene Therapeutics: Research Funding; Juno Therapeutics, a Bristol-Myers Squibb Company: Research Funding. Hultcrantz:Intellisphere LLC: Consultancy; Amgen: Research Funding; Daiichi Sankyo: Research Funding; GSK: Research Funding. Hassoun:Takeda: Research Funding; Celgene: Research Funding; Novartis: Consultancy. Scordo:McKinsey & Company: Consultancy; Angiocrine Bioscience, Inc.: Consultancy, Research Funding; Omeros Corporation: Consultancy; Kite - A Gilead Company: Other: Ad-hoc advisory board. Chung:Genentech: Research Funding. Shah:Amgen: Research Funding; Janssen Pharmaceutica: Research Funding. Lahoud:MorphoSys: Other: Advisory Board. Thoren:Sebia: Research Funding; The Binding Site: Research Funding. Ho:Invivoscribe, Inc.: Honoraria. Dogan:AbbVie: Consultancy; EUSA Pharma: Consultancy; Takeda: Consultancy; Seattle Genetics: Consultancy; Corvus Pharmaceuticals: Consultancy; Physicians Education Resource: Consultancy; Roche: Consultancy, Research Funding; National Cancer Institute: Research Funding. Giralt:MILTENYI: Consultancy, Research Funding; ACTINUUM: Consultancy, Research Funding; KITE: Consultancy; OMEROS: Consultancy, Honoraria; NOVARTIS: Consultancy, Honoraria, Research Funding; CELGENE: Consultancy, Honoraria, Research Funding; JAZZ: Consultancy, Honoraria; AMGEN: Consultancy, Research Funding; TAKEDA: Research Funding. Landgren:Takeda: Other: Independent Data Monitoring Committees for clinical trials, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Binding Site: Consultancy, Honoraria; Karyopharma: Research Funding; Janssen: Consultancy, Honoraria, Other: Independent Data Monitoring Committees for clinical trials, Research Funding; Seattle Genetics: Research Funding; Glenmark: Consultancy, Honoraria, Research Funding; Takeda: Other: Independent Data Monitoring Committees for clinical trials, Research Funding; Janssen: Consultancy, Honoraria, Other: Independent Data Monitoring Committees for clinical trials, Research Funding; Pfizer: Consultancy, Honoraria; Merck: Other; Cellectis: Consultancy, Honoraria; BMS: Consultancy, Honoraria; Juno: Consultancy, Honoraria; Glenmark: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy, Honoraria; Seattle Genetics: Research Funding; Karyopharma: Research Funding; Merck: Other; Adaptive: Consultancy, Honoraria; Amgen: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Binding Site: Consultancy, Honoraria; BMS: Consultancy, Honoraria; Cellectis: Consultancy, Honoraria; Juno: Consultancy, Honoraria.

Chronic myeloid neoplasms are group of clinically heterogenous diseases characterized by a wide range of abnormalities affecting the function of cells in the myeloid lineage. Their classification is based on an integrated, multimodality approach that requires the strict correlation of clinical, morphologic, and genetic features. Cytogenetic and molecular genetic studies are an essential component of the assessment of these patients at the time of diagnosis and in the monitoring phase to assess disease progression and for risk stratification across the disease spectra. In this chapter, we highlight the most common somatic genetic abnormalities identified in this group of diseases.

Immunoglobulin heavy chain (IGH) clonality testing by next-generation sequencing (NGS) offers unique advantages over current low-throughput methods in the assessment of B-cell lineage neoplasms. Clinical use remains limited because assays are not standardized and validation/implementation guidelines are not yet developed. Herein, we describe our clinical validation and implementation of NGS IGH clonality testing and summarize our experience based on extensive routine use. NGS-based clonality testing targeting IGH FR1, FR2, FR3, and the conserved leader sequence upstream of FR1 was validated using commercially available kits. Data were analyzed by commercial and in-house–developed bioinformatics pipelines. Performance characteristics were evaluated directly comparing with capillary electrophoresis (CE) assays (BIOMED-2 primers). Assays were monitored after implementation (>1.5 years), concurrently testing by CE methods. A total of 1189 clinical samples were studied (94 validation, 1095 postimplementation). NGS showed superior performance compared with CE assays. For initial assessment, clonality detection rate was >97% for all malignancy types. Concordance with CE was 96%; discordances were related to higher sensitivity/resolution of NGS and improved detection in cases with high somatic hypermutation. Routine NGS clonality assessment is feasible and superior to existing assays, enabling accurate and specific index clone assessment and future tracking of all rearrangements in a patient sample. Successful implementation requires new standardization, validation, and implementation processes, which should be performed as a multicenter and multidisciplinary collaboration.

NPM1-mutated myeloid neoplasms (NPM1(+) MNs) with

Multiple Myeloma, the second most prevalent hematologic malignancy, yet lacks an established curative therapy. However, overall response rate to modern four-drug regimens approaches 100%. Major efforts have thus focused on the measurement of minute quantities of residual disease (minimal residual disease or MRD) for prognostic metrics and therapeutic response evaluation. Currently, MRD is assessed by flow cytometry or by next generation sequencing to track tumor-specific immunoglobulin V(D)J rearrangements. These bone marrow-based methods can reach sensitivity thresholds of the identification of one neoplastic cell in 1,000,000 (10(−6)). New technologies are being developed to be used alone or in conjunction with established methods, including peripheral blood-based assays, mass spectrometry, and targeted imaging. Data is also building for MRD as a surrogate endpoint for overall survival. Here, we will address the currently utilized MRD assays, challenges in validation across labs and clinical trials, techniques in development, and future directions for successful clinical application of MRD in multiple myeloma.

Lymphoid neoplasms show great diversity in morphology, immunophenotypic profile, and postulated cells of origin, which also reflects the variety of genetic alterations within this group of tumors. This review discusses many of the currently known genetic alterations in selected mature B-cell and T-cell lymphoid neoplasms, and their significance as diagnostic, prognostic, and therapeutic markers. Given the rapidly increasing number of genetic alterations that have been described in this group of tumors, and that the clinical significance of many is still being studied, this is not an entirely exhaustive review of all of the genetic alterations that have been reported.

INTRODUCTION. Recent studies show that ~25% of newly diagnosed multiple myeloma patients treated with 8 cycles of bortezomib, lenalidomide and dexamethasone (VRd) achieve minimal residual disease (MRD) negativity. Recently, 42% stringent complete response (sCR) rates were reported with the use of VRd combined with the CD38-targeted monoclonal antibody daratumumab (VRd-D). Here, we present the final results from a phase 2 study using weekly dosing of carfilzomib 56 mg/m2 with lenalidomide and dexamethasone in combination with daratumumab (wKRd-D). The primary endpoint of our study was to demonstrate >60% and to target up to 80% MRD negativity rate with wKRd-D. METHODS. This phase II clinical trial is based on Simon's optimal two-stage design. The wKRd-D dosing schedule is as follows: 8 cycles of treatment; 28-day cycles with IV carfilzomib 20/56 mg/m2 days 1, 8, and 15; PO lenalidomide 25 mg days 1-21; PO/IV dexamethasone 40 mg weekly cycles 1-4, 20 mg after cycle 4; and IV daratumumab 16 mg/kg days 1, 8, 15, and 22 cycles 1-2, days 1 and 15 cycles 3-6, and day 1 cycles 7-8. For fit patients, stem cell collection is recommended after 4 to 6 cycles of therapy; wKRd-D therapy resumed after collection to a total of 8 cycles wKRd-D. Treatment response is being assessed with parallel bone marrow-based MRD assays (10-color single tube flowcytometry and invivoscribe IGHV sequencing); per IMWG guidelines both MRD assays allows detection of 1 myeloma cell in 100,000 cells (10^-5). Baseline bone marrow samples are evaluated with targeted DNA sequencing for FISH-Seq and somatic mutational characteristics (myTYPE). RESULTS. The study is fully enrolled; between October 2018 and November 2019 a total of 41 evaluable patients were enrolled. Baseline characteristics include; median age 59 years (range 30-70 years); 25 (61%) females;16 (39%) males; 20 (49%) patients had high-risk FISH/SNP signature defined as one or more of the following: 1q+, t(4;14), t(14;16), t(14;20), and 17p-. At submission of this abstract, 39 out of 41 patients have completed 8 cycles of treatment and end of treatment evaluations. Of those 39, 29 patients were MRD negative and 10 patients MRD positive. Two patients are pending end of treatment evaluations for response (currently receiving cycle 8 of wKRd-D). Thus, among patients treated on the weekly cohort (wKRd-D) and who were evaluable for the MRD primary endpoint at this analysis, we found 29/39 (74%) to be MRD negative. We further show no added major clinical toxicities with wKRd-D compared to our institution standard of care KRd. At a median follow-up of 10 months, none of the MRD negative patients have progressed. Among 29 patients found to be MRD negative after 8 cycles of wKRd-D, 2 patients have been assessed for MRD at 1 year of follow-up and 2/2 (100%) show 1-year sustained MRD negativity. There are no deaths on the study. CONCLUSIONS. Among patients evaluable for the MRD primary endpoint, in the absence of an autologous bone marrow transplant, here we show a 29/39 (74%) MRD negativity rate among newly diagnosed multiple myeloma patients treated with wKRd-D, including weekly carfilzomib 56 mg/m2 dosing. At a median follow-up of 10 months, none of the MRD negative patients have progressed. These results compare favorably with previously published results with KRd, VRd, or VRd-D. Using optimized IV fluid management (250 ml saline prior to first dose of carfilzomib only, and thereafter no IV fluids) coupled with baseline work-up with EKG/echocardiograms for all patients, we did not observe excess rates of cardiovascular or renal adverse event. The wKRd-D dosing schedule has a total of 27 infusions and offers an attractive treatment modality for newly diagnosed multiple myeloma patients. Based on these promising results, a large randomized multi-center study ("ADVANCE") evaluating wKRd-D in relation to established standard of care has been opened for enrollment. Disclosures Landgren: Adaptive: Consultancy, Honoraria; BMS: Consultancy, Honoraria; Juno: Consultancy, Honoraria; Cellectis: Consultancy, Honoraria; BMS: Consultancy, Honoraria; Binding Site: Consultancy, Honoraria; Karyopharma: Research Funding; Merck: Other; Pfizer: Consultancy, Honoraria; Seattle Genetics: Research Funding; Juno: Consultancy, Honoraria; Glenmark: Consultancy, Honoraria, Research Funding; Cellectis: Consultancy, Honoraria; Glenmark: Consultancy, Honoraria, Research Funding; Takeda: Other: Independent Data Monitoring Committees for clinical trials, Research Funding; Amgen: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Honoraria, Other: Independent Data Monitoring Committees for clinical trials, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Seattle Genetics: Research Funding; Merck: Other; Pfizer: Consultancy, Honoraria; Takeda: Other: Independent Data Monitoring Committees for clinical trials, Research Funding; Binding Site: Consultancy, Honoraria; Karyopharma: Research Funding; Janssen: Consultancy, Honoraria, Other: Independent Data Monitoring Committees for clinical trials, Research Funding. Hultcrantz:Intellisphere LLC: Consultancy; Amgen: Research Funding; GSK: Research Funding; Daiichi Sankyo: Research Funding. Lesokhin:BMS: Consultancy, Honoraria, Research Funding; Genentech: Research Funding; Janssen: Research Funding; GenMab: Consultancy, Honoraria; Juno: Consultancy, Honoraria; Takeda: Consultancy, Honoraria; Serametrix Inc.: Patents & Royalties. Mailankody:Janssen Oncology: Research Funding; Juno Therapeutics, a Bristol-Myers Squibb Company: Research Funding; Allogene Therapeutics: Research Funding; PleXus Communications: Honoraria; Physician Education Resource: Honoraria; Takeda Oncology: Research Funding. Hassoun:Novartis: Consultancy; Celgene: Research Funding; Takeda: Research Funding. Shah:Celgene/BMS: Research Funding; Physicians Education Resource: Honoraria. Scordo:McKinsey & Company: Consultancy; Angiocrine Bioscience, Inc.: Consultancy, Research Funding; Omeros Corporation: Consultancy; Kite - A Gilead Company: Other: Ad-hoc advisory board. Chung:Genentech: Research Funding. Shah:Amgen Inc.: Research Funding; Janssen: Research Funding. Lahoud:MorphoSys: Other: Advisory Board. Thoren:The Binding Site: Research Funding; Sebia: Research Funding. Murata:Abbott Laboratories: Research Funding. Ho:Invivoscribe, Inc.: Honoraria. Dogan:Roche: Consultancy, Research Funding; Physicians Education Resource: Consultancy; Corvus Pharmaceuticals: Consultancy; Seattle Genetics: Consultancy; Takeda: Consultancy; EUSA Pharma: Consultancy; AbbVie: Consultancy; National Cancer Institute: Research Funding. Giralt:CSL Behring: Research Funding; Jazz: Research Funding; Actinuum: Research Funding; Amgen: Research Funding; Janssen: Research Funding; Celgene: Research Funding; Quintiles: Research Funding; Pfizer: Research Funding; Sanofi: Research Funding; Adienne: Research Funding; Kite: Research Funding. Korde:Astra Zeneca: Membership on an entity's Board of Directors or advisory committees; Amgen: Research Funding. OffLabel Disclosure: Daratumumab, Carfilzomib, Lenalidomide, and Dexamethasone in Newly-Diagnosed Multiple Myeloma. These drugs are included in the current clinical and correlative Phase II study

TP53 alterations portend extremely poor prognosis in patients with mantle cell lymphoma treated with standard treatment modalities. We reviewed outcomes of 42 patients with available TP53 status who had received a reduced-intensity or non-myeloablative allogeneic haematopoietic cell transplant at our institution. We demonstrated a 2-year overall survival and progression-free survival of 78% [95% confidence interval (CI) 60-88] and 61% (95% CI 43-75), respectively. The 2-year cumulative incidences of relapse and non-relapse mortality were 19% and 20%, respectively. Importantly, there is no significant difference among patients with and without TP53 alterations, suggesting for the first time a beneficial treatment modality for these high-risk patients.

After therapy or stem cell transplantation, multiple myeloma patients achieving complete response or stringent complete response can still have a significant risk of disease relapse. This highlights the importance of using highly sensitive laboratory methods for minimal residual disease detection and prognostication. Older methods such as allele-specific oligonucleotide real time quantitative polymerase chain reaction and fluorescent polymerase chain reaction have their drawbacks. Meanwhile, the recent generation of multiparametric flow cytometry and next-generation sequencing (NGS)-based detection methods currently offer the highest technical sensitivities, and are likely to gain more widespread use and be recognized as the standard of care for disease monitoring in myeloma patients.

Background: Over 300 somatic molecular variants in hematologic diseases are either specified as diagnostic criteria in the World Health Organization (WHO) Classification of Tumors of Hematopoietic and Lymphoid Tissues, recognized as potentially actionable biomarkers in the National Comprehensive Cancer Network (NCCN) compendia, or supported by published well-powered clinical studies. Moreover, new molecular alterations with potential clinical implications in hematologic disease are continuously emerging in the scientific literature. These have critical use for a wide spectrum of clinicians, including hematopathologists who diagnose patient-specific hematologic malignancies, heme-oncologists who direct patient care, and clinical trial nurses who assist patients in finding appropriate clinical trials. Importantly, the utility of this information critically depends on the clinician's ability to interpret the significance of variants in a point-of-care setting. Therefore, there is an urgent and unmet need for a clinical decision support system that 1) distills the clinical implications associated with molecular alterations into a standardized and easily interpretable format and 2) democratizes access of this information to all members of the heme-oncology community. Methods: OncoKB is an established expert-guided precision oncology knowledge base that annotates the oncogenic effect and therapeutic implications of somatic molecular alterations (Chakravarty, D. et al., JCOPO, 2017). Previously, OncoKB was focused primarily on solid tumor mutation annotation. Recently, we expanded OncoKB to include alterations in hematologic malignancies. The heme-specific annotation efforts were guided by heme-oncology and hematopathology physician scientists at Memorial Sloan Kettering (MSK). Supplementing the previously published therapeutic levels of evidence (Fig. 1a), we further added level of evidence systems for diagnostic and prognostic implications (Fig. 1b, c). These three sets of evidence levels are consistent with the criteria set forth by the joint consensus of the ASCO/CAP/AMP guidelines (Li, MM. et al., J Mol Diagn, 2017). We assigned the newly curated heme-specific molecular alterations with diagnostic, prognostic or therapeutic levels of evidence, when applicable. Finally, we annotated and analyzed 1569 hematologic tumor samples from the AACR Project GENIE (release 6.1) with these levels of evidence. Results: In addition to alterations with both solid and heme clinical implications already curated in OncoKB, we annotated 288 unique heme-specific mutations, fusions, and copy number alterations in 156 newly curated cancer-associated genes. Based on MSK-expert consensus, the WHO and NCCN guidelines, and the scientific literature, we identified a total of 192 alterations with unique diagnostic levels of evidence, 65 alterations with unique prognostic levels of evidence and 55 alterations with unique therapeutic levels of evidence across 13 major hematologic tumor types (Fig. 2). To test the utility of OncoKB, we annotated all genomic events in 1569 heme cancer samples in 89 hematologic malignancies in the AACR GENIE cohort (V6.1) (Fig. 3a). Thirty-eight percent of samples harbored at least one potentially actionable alteration, and 8% were predictive of clinical benefit from an FDA-approved drug (Fig. 3b). Conclusions: OncoKB heme data is publicly available both through the web resource http://oncokb.org and through incorporation into the cBioPortal for Cancer Genomics. Heme-specific molecular alterations are used to make an accurate diagnosis, inform prognosis, optimize the use of stem cell transplant, and to link patients with the optimal mechanism-based therapies in the clinical trial setting and in routine clinical practice. This is the first study to annotate and analyze actionability of heme samples. In this proof-of-principle study, we demonstrate the ability to annotate clinical samples with their diagnostic, prognostic and therapeutic implications in a point-of-care setting. Disclosures Roshal: Celgene: Other: Provision of Services; Auron Therapeutics: Equity Ownership, Other: Provision of services; Physicians' Education Resource: Other: Provision of services. Ho:Invivoscribe, Inc.: Honoraria. Knorr:Fate Therapeutics: Patents & Royalties. LaFave:Epizyme: Patents & Royalties. Arcila:Invivoscribe, Inc.: Consultancy, Honoraria. Berger:Roche: Consultancy. Solit:Pfizer: Consultancy; Lilly Oncology: Honoraria; Vivideon Therapeutics: Consultancy; Loxo Oncology: Consultancy, Equity Ownership; Illumina: Consultancy. Dogan:Celgene: Consultancy; Seattle Genetics: Consultancy; Corvus Pharmaceuticals: Consultancy; Roche: Consultancy, Research Funding; Novartis: Consultancy; Takeda: Consultancy. Levine:C4 Therapeutics: Membership on an entity's Board of Directors or advisory committees; Qiagen: Membership on an entity's Board of Directors or advisory committees; Isoplexis: Membership on an entity's Board of Directors or advisory committees; Loxo: Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Research Funding; Novartis: Consultancy; Gilead: Consultancy; Imago Biosciences: Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria; Lilly: Honoraria; Prelude Therapeutics: Research Funding; Roche: Consultancy, Research Funding.

Background. Prior studies consistently show that the use of maintenance therapy after completion of combination therapy translates into longer progression-free survival (PFS) in patients with multiple myeloma. Some studies show that maintenance therapy prolongs overall survival (OS). Typically, maintenance therapy is used in the setting of newly diagnosed multiple myeloma; however, emerging data suggest that (at least a subset of) patients in the early relapse setting, for example those who achieve MRD negativity, may also be candidates for maintenance therapy integrated with careful disease monitoring. Currently, lenalidomide is considered the standard of care for maintenance; however, there is only limited published data on long-term use, with respect to the ability to sustain MRD negativity, mechanisms of relapse, and late toxicities. We were motivated to develop a study focusing on long-term lenalidomide maintenance therapy and to study clinical and correlative data. Here, we report on sustained MRD negativity and clinical tolerability. Methods. This single arm, phase 2 was designed to enroll 100 evaluable patients. Per protocol, maintenance therapy with lenalidomide 10 mg is given days 1-21 on a 28-day cycle. The initial study design had a total duration of 36 months; it was subsequently extended with additional 24 months (i.e., total of 60 months). Per standard procedures for protocol amendments, patients were offered to re-consent for the extension. Per protocol, patients underwent bone marrow biopsies and aspirates as well as PET/CT exams at baseline, annually, at progression/end of treatment; blood work was done every 3 months. Bone marrow and blood samples were banked longitudinally per the research protocols. Based on practical considerations, the study was statistically powered for the primary end-point progression-free survival, which provided sufficient numbers of samples for the planned correlative assays focusing on MRD testing, genomic characterization of detectable disease, and profiling of the bone marrow microenvironment. All these assays were conducted in serial samples collected over time and assessed in relation to clinical outcomes. Results. A total of 100 evaluable patients meeting eligibility criteria were enrolled (63% males) between September 2015 and January 2019. Baseline characteristics include median age 63 years (range 38-86 years) and median ECOG score 1 (range 0-1). At the submission of this abstract, the median number of cycles delivered is currently 26 (range 1 to 48); 86 patients have completed 12 or more cycles, 57 patients have completed 24 or more cycles, and 29 patients have completed 36 or more cycles. MRD testing had been completed at least once in all patients. Thirty-four patients were MRD negative at enrollment. At median followup time of 28 months (range 3.4 to 45.6), 15/100 (15%) patients have progressed. Considering the entire follow-up time from initial MRD negativity to last follow-up on study, we found 39 (of 85 tested; 46%) and 25 (of 57 tested; 44%) to have evidence of 1 and 2 years sustained MRD negativity, respectively. Only 19 patients were tested for MRD at 3 years and 16 (84%) had sustained MRD negativity. Toxicities (grade 3) include neutrophil count decrease (N=9), hypertension (N=3), diarrhea (N=2), lung infection (N=2), and rash maculo-papular (N=2), and toxicities (grade 4) include sepsis (N=2) and platelet count decrease (N=1). The most common 1/2 toxicities were diarrhea (N=51), fatigue (N=33), and upper respiratory infection (N=23). Among evaluable patients, dose reductions of lenalidomide due to toxicities and tolerability issues were done in 6 (6%) patient. Conclusions. Among evaluable patients who were treated with lenalidomide 10 mg maintenance therapy days 1-21 on a 28-day cycle on this study, at a median followup of 28 months, we found 46% and 44% to have evidence of 1 and 2 years sustained MRD negativity, respectively. Currently, 19 patients have been tested for MRD at 3 years; 16 (84%) show evidence of 3 years sustained MRD negativity. The toxicity profile was in accord with prior studies and tolerability was quite good reflected in only 6 patients requiring dose reductions due to toxicities. Correlative assays focusing on mechanisms of sustained MRD negativity in this study are presented in a separate abstract at this meeting. Disclosures Landgren: Adaptive: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Theradex: Other: IDMC; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Abbvie: Membership on an entity's Board of Directors or advisory committees; Sanofi: Membership on an entity's Board of Directors or advisory committees; Karyopharm: Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Merck: Other: IDMC. Lesokhin:Genentech: Research Funding; GenMab: Consultancy, Honoraria; Janssen: Research Funding; Serametrix Inc.: Patents & Royalties; Juno: Consultancy, Honoraria; BMS: Consultancy, Honoraria, Research Funding; Takeda: Consultancy, Honoraria. Smith:Celgene: Consultancy, Patents & Royalties, Research Funding; Fate Therapeutics and Precision Biosciences: Consultancy. Mailankody:Juno: Research Funding; Celgene: Research Funding; Janssen: Research Funding; Takeda Oncology: Research Funding; CME activity by Physician Education Resource: Honoraria. Hassoun:Janssen: Research Funding; Celgene: Research Funding; Novartis: Consultancy. Landau:Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Karyopharm: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Research Funding; Caelum: Membership on an entity's Board of Directors or advisory committees; Prothena: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees. Scordo:Angiocrine Bioscience, Inc.: Consultancy; McKinsey & Company: Consultancy. Arcila:Invivoscribe, Inc.: Consultancy, Honoraria. Ho:Invivoscribe, Inc.: Honoraria. Roshal:Physicians' Education Resource: Other: Provision of services; Celgene: Other: Provision of Services; Auron Therapeutics: Equity Ownership, Other: Provision of services. Dogan:Roche: Consultancy, Research Funding; Corvus Pharmaceuticals: Consultancy; Seattle Genetics: Consultancy; Celgene: Consultancy; Takeda: Consultancy; Novartis: Consultancy.

Introduction: Next-generation sequencing (NGS)-based IGH clonal rearrangement assays can characterize and subsequently track disease-associated clonal sequences for lymphoid and plasma cell neoplasms, even at very low levels. As IGH PCR primers are used, the detected clonal sequences are usually reported as % of sequencing reads, roughly corresponding to % of B and plasma cells (PC) in samples, rather than % of total cellularity, hampering accurate disease burden assessment. In this study, we evaluated a method for calculating residual disease burden as % of total cellularity, with the aid of adding a known quantity of "spike-in" clonal sequence to the samples, and compared to concurrent 10-color flow cytometry (FC) quantitation of abnormal PC. Methods: DNA was extracted from 40 plasma cell myeloma patient marrow biopsies sent for disease monitoring purposes at Memorial Sloan Kettering Cancer Center (MSKCC), with previously-characterized clonal sequences specific to the patients' myelomas. All samples had concurrent FC analyses and aspirate differential counts performed. 100 cell equivalent of DNA with a known clonal sequence (LymphoQuant®, LQ) was added to 700ng of patient DNA (~100,000 cell equivalent), and testing was performed using LymphotrackTM, a NGS-based assay. Following PCR amplification using IGH FR1 primers, sequencing was performed on the Illumina MiSeqTM instruments at the molecular laboratory of MSKCC. Reproducibility studies were conducted on a subset of samples at the laboratory of Invivoscribe, Inc. using identical methodology. LymphoTrack MRD data analysis tool (MRDDAT) v.1.0.3 was used to search for both the myeloma-specific and LQ clonal sequences. Disease as # of cell equivalent was calculated as: (% reads for myeloma clonal sequence/% reads for LQ) X 100 cells. Disease as % of total cellularity was calculated as: (# of cell equivalent/100,000 cells) X 100%. Results: Disease as % of total cellularity calculated by LQ showed a median of 0.7576% cells (range: 0.000614% to 39.89%), compared to abnormal PC as % of total WBC by FC with a median of 0.355% cells (range: 0.00061% to 44.70%). Overall, a good correlation between disease quantitation by LQ and FC could be observed for cases with ≤10% total PC by aspirate count (r=0.79), while the correlation is lower for cases with >10% total PC (r=0.51). 12/40 samples were tested in two different laboratories, and showed excellent correlation in disease quantitation by LQ (r=0.94). As expected, detectable clonal sequences as % of sequencing reads (rather than as % of total cellularity) showed poor correlation with FC quantitation (r=0.32), due to variability of total B and plasma cell content in different samples. Conclusions: Disease as % of total cellularity calculated with the aid of a known "spike-in" sequence in the NGS-based assay showed good correlation with the quantitation of abnormal PC by FC, when total PC was ≤10% by aspirate count. The correlation between the two declines when total PC was >10%. When patient samples contain a high number of B and/or plasma cells, the PCR amplification efficiency of the very small amount of the admixed "spike-in" clonal sequence may be hampered, affecting accurate quantitation. Furthermore, FR1 primers may not anneal optimally to some patients' clonal sequences due to somatic hypermutations in binding sites, underestimating the % of disease clone. Utilization of a second "spike-in" sequence and other primer sets (FR2, FR3) may improve disease % calculations in some cases. Disclosures Ho: Invivoscribe, Inc.: Honoraria. Roshal:Celgene: Other: Provision of Services; Auron Therapeutics: Equity Ownership, Other: Provision of services; Physicians' Education Resource: Other: Provision of services. Huang:Invivoscribe, Inc.: Employment. Hutt:Invivoscribe, Inc.: Employment. Miller:Invivoscribe, Inc.: Employment. Landgren:Theradex: Other: IDMC; Abbvie: Membership on an entity's Board of Directors or advisory committees; Sanofi: Membership on an entity's Board of Directors or advisory committees; Merck: Other: IDMC; Adaptive: Honoraria, Membership on an entity's Board of Directors or advisory committees; Karyopharm: Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Arcila:Invivoscribe, Inc.: Consultancy, Honoraria.

Background: As the repertoire of molecular targeted therapies for hematologic malignancies continues to expand, so too does the opportunity for molecular profiling to inform treatment decisions. While mutations in certain genes, such as JAK2, MPL, MYD88 and BRAF have diagnostic utility, others such as FLT3, NPM1, IDH1, IDH2, DNMT3A, KIT and CEBPA have prognostic value. Here, we present the development and clinical experience of MSK-IMPACT Heme (Integrated Mutation Profiling of Actionable Cancer Targets for Hematologic malignancies), a comprehensive molecular profiling platform, utilizing hybridization capture and high coverage next generation sequencing of paired tumor and normal tissues. Methods: We designed custom DNA probes corresponding to all exons of 400 key oncogenes and tumor suppressor genes implicated in hematologic malignancies, including all genes that are targetable by approved and experimental therapies being investigated in clinical trials at our institution. The accuracy, precision, and sensitivity of MSK-IMPACT Heme was assessed on a validation set of 113 unique tumor samples with known SNVs and indels previously confirmed by orthogonal methods. We implemented a custom analysis pipeline to integrate the analysis of any number of normal samples with a given tumor and provide a reliable assessment of somatic alterations, even in post-transplant chimeric patients. The selection of matched nail, saliva, and/or blood tissue was determined at the time of test initiation as indicated by patient diagnosis and transplant history. The ability to detect somatic copy number alterations was demonstrated with samples previously characterized by SNP array platforms. Results: We sequenced 821 tumor samples, from 759 patients that represented over 50 tumor types to a mean depth of 758X. 429 patients were male (56.5%) and 20 cases were post allogeneic stem cell transplantation. The most common tumor types sequenced were Follicular lymphoma (11.9%), DLBCL (11.3%), and AML (11.0%). We identified 4,935 mutations from 732 samples. The most commonly altered genes were TP53, KMT2D, and CREBBP. Implementation of the MSK-IMPACT Heme workflow enabled the characterization of complex tumor specimens, including sorted cells and tumor samples from post-transplant chimeric patients. The joint utilization of matched patient and donor normal tissues enabled differentiation between somatic alterations and both host and donor derived common polymorphisms. Conclusions: The MSK-IMPACT Heme assay provides molecular profiling of hematologic malignancies with high accuracy and sensitivity. Paired analysis of tumors and patient and/or donor matched normal tissue samples enables the unambiguous detection of somatic alterations and the ability apply these data towards tumor classification, risk assessment, prognosis, disease monitoring, and treatment optimization. Citation Format: Ryan N. Ptashkin, Ryma Benayed, John Ziegler, Anoop Balakrishnan Rema, Justyna Sadowska, Iwona Kiecka, Caleb Ho, JinJuan Yao, Christine Moung, Kseniya Petrova-Drus, Khedoudja Nafa, Connie Batlevi, Martin Tallman, Ross Levine, Sergio Giralt, Anas Younes, Marc Ladanyi, Mike Berger, Ahmet Zehir, Maria E. Arcila. MSK-IMPACT Heme: Validation and clinical experience of a comprehensive molecular profiling platform for hematologic malignancies [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3409.

Tracking of clonal immunoglobulin V(D)J rearrangement sequences by next generation sequencing is highly sensitive for minimal residual disease in multiple myeloma. However, previous studies have found variable rates of V(D)J sequence identification at baseline, which could limit tracking. Here, we aimed to define the factors influencing the identification of clonal V(D)J sequences. Bone marrow mononuclear cells from 177 myeloma patients underwent V(D)J sequencing by the LymphoTrack assays (Invivoscribe). As a molecular control for tumor cell content, we sequenced the samples using our in-house myeloma panel myTYPE. V(D)J sequence clonality was identified in 81% of samples overall, as compared with 95% in samples where tumor-derived DNA was detectable by myTYPE. Clonality was detected more frequently in patients with lambda-restricted disease, mainly because of increased detection of kappa gene rearrangements. Finally, we describe how the tumor cell content of bone marrow aspirates decrease gradually in sequential pulls because of hemodilution: From the initial pull used for aspirate smear, to the final pull that is commonly used for research. In conclusion, baseline clonality detection rates of 95% or higher are feasible in multiple myeloma. Optimal performance depends on the use of good quality aspirates and/or subsequent tumor cell enrichment.

Lymphoid neoplasms show great diversity in morphology, immunophenotypic profile, and postulated cells of origin, which also reflects the variety of genetic alterations within this group of tumors. This review discusses many of the currently known genetic alterations in selected mature B-cell and T-cell lymphoid neoplasms, and their significance as diagnostic, prognostic, and therapeutic markers. Given the rapidly increasing number of genetic alterations that have been described in this group of tumors, and that the clinical significance of many is still being studied, this is not an entirely exhaustive review of all of the genetic alterations that have been reported.

Crystals and crystalloids may be seen in salivary glands in association with tumors and cysts. Rarely, crystalloids may lead to granulomatous reaction mimicking neoplasm and infectious diseases. We present the case of an 81-year-old man with right parotid gland swelling and a clinical and radiological diagnosis of tumor. A granulomatous inflammation was seen on intraoperative pathology. On final pathology, the parotid gland showed multiple granulomas with central cavitation and palisading histiocytes with eosinophilic intracytoplasmic and extracellular crystalloids. The crystalloids were variably shaped, needle-like, polyhedral, rhomboid, rectangular and irregular, nonpolarizable, nonbirefringent, and nonrefractile and were orange-red with trichrome and bluish-purple with Brown and Brenn stain. Remnants of a duct lining within the lesion suggested a granulomatous response to ruptured cyst contents releasing secretions supersaturated in proteins and their precipitates.