ALBERT

Description: Background: Ten to 15% of diffuse large B cell lymphoma (DLBCL) patients exhibit primary refractory disease (nonresponse or relapse within 3 months of therapy) and an additional 20-25% relapse following initial response. There is an unmet need for effective therapeutic regimens in relapsed/refractory (R/R) DLBCL. Lenalidomide is an immune modulator that reverses T cell dysfunction and also inhibits the NFκB pathway, which is constitutively active in non-germinal center (non-GCB) DLBCL. Lenalidomide and nivolumab, an anti-PD-1 antibody, each have single agent activity in R/R DLBCL. Here, we report the results of the dose-escalation cohort of this investigator-initiated, single-arm open-label study of the combination of nivolumab, lenalidomide and rituximab (NiLeRi) in R/R non-GCB DLBCL. Methods: Adult patients with R/R non-GCB DLBCL, as determined by the Hans algorithm, with adequate organ function and an ECOG performance status of ≤2 were eligible for the study. The primary objective was to evaluate the safety of NiLeRi, and determine the maximum tolerated dose (MTD) of lenalidomide in combination with fixed doses of rituximab and nivolumab, using a 3+3 dose escalation design. The secondary objectives were to determine efficacy in terms of overall response rate (ORR), progression free survival (PFS), and overall survival (OS) of patients treated with NiLeRi. All patients received nivolumab IV 3 mg/kg on days 1 and 15 and rituximab IV 375mg/m2 on day 1 of each 28-day cycle. Lenalidomide was initiated at 5 mg po once daily on days 1-21. Additional planned dose levels were 10 mg, 15 mg and 20 mg. Patients were evaluable for toxicity if they received all doses of nivolumab and rituximab and at least 16 doses of lenalidomide during cycle 1 or if they experienced a dose limiting toxicity (DLT), regardless of the number of doses. NiLeRi was given for 8 cycles and patients with partial response could receive lenalidomide and nivolumab for an additional 4 cycles. Response was assessed by PET-CT after 2, 5 and 8 cycles and defined by Lugano criteria. Results: Six patients with non-GCB subtype of DLBCL were enrolled in this study. The median age was 60.5 years (range 28-79), and 5 patients were male. The median number of prior lines of therapy was 4 (range 2-5), and the median IPI score was 3. None of the patients had bone marrow involvement. One patient each had been treated with autologous stem cell transplant (Auto-SCT) and CAR-T cell therapy. One patient withdrew consent before completing cycle 1 and was not evaluable for safety or efficacy. Safety: Five out of the six enrolled patients were evaluable for safety. All patients received lenalidomide 5 mg dose. Two patients experienced DLTs (grade 3 rash) resulting in lenalidomide discontinuation during cycle 2. The most common grade 3/4 toxicities were fatigue (20%), neutropenia (60%), thrombocytopenia (40%), and rash (40%). A total of 3 patients experienced grade 1/2 diarrhea and elevated liver enzymes. One patient experienced a grade 1 infusion reaction with rituximab. Efficacy: Patients who completed at least 1 cycle of therapy were evaluable for response, and this included 5 out of the 6 enrolled patients. The ORR and complete response (CR) rate were both 40%. Patients who responded did so early, with one patient achieving CR after 2 cycles and another patient achieving CR after 5 cycles. The best response seen in patients with primary refractory disease was PR. At a median follow up of 9.5 months, median PFS was 8.4 months (95% CI; 4.3 to not reached), and median OS was not reached. Discussion: This is the first study reporting the safety results of the combination of lenalidomide, nivolumab and rituximab in non-Hodgkin lymphoma. Rash was the most common DLT, limiting dose escalation of lenalidomide above 5mg in this cohort of patients. Two patients experienced durable CR early in the study after 2 and 5 cycles, respectively. This ORR and CR rate of 40% each in this small cohort of patients who had relapsed after multiple prior lines of therapy is encouraging. Correlative studies, including whole exome sequencing of patient samples, are underway, in an attempt to explore predictive markers for response and toxicity. Figure. Disclosures Mason: Sysmex: Honoraria. Oluwole:Pfizer: Consultancy; Spectrum: Consultancy; Gilead Sciences: Consultancy; Bayer: Consultancy. Morgan:Biogen: Equity Ownership; Eli Lilly: Equity Ownership; Vertex: Equity Ownership; Zoetis: Equity Ownership; Pfizer: Equity Ownership; Novo Nordisk: Equity Ownership; Gilead: Equity Ownership; Johnson and Johnson: Equity Ownership; Merck: Equity Ownership. Reddy:Abbvie: Consultancy; Genentech: Research Funding; Celgene: Consultancy; BMS: Consultancy, Research Funding; KITE Pharma: Consultancy. OffLabel Disclosure: Nivolumab and lenalidomide are not FDA approved for use in diffuse large B cell lymphoma

Description: Follicular Lymphoma (FL) is the most common indolent lymphoma derived from light zone germinal center B cells and characterized by a t(14;18) translocation resulting in upregulation of BCL2 in over 80% of cases. This translocation alone is not sufficient for tumorogenesis, and must be combined with additional genetic mutations to transform B cells. FL is incurable and the disease course can be highly varied, with survival ranging from a few months to decades following diagnosis and treatment with standard chemoimmunotherapy. The heterogeneity of FL poses major challenges to identifying the association of genetic alterations and clinical outcome. Current WHO guidelines recommend establishing grade for each FL case with grade 3 thought to be more aggressive than 1 and 2. The genetic basis and clinical implications of grade in FL are unclear. Recent sequencing studies have identified many genes found to be recurrently mutated in FL including KMT2D and CREBBP. However, the degree to which genetic alterations cooperate with each other or contribute to clinical outcome is unclear. Based on the observed mutational rates in follicular lymphoma, we estimated 900 cases were needed to comprehensively delineate the genetic alterations that underlie histologic grade and clinical outcome. Accordingly, we enrolled a cohort of 1042 patients with newly diagnosed FL. All treated patients received rituximab-containing standard regimens. To go beyond the identification of gene-coding events, we developed a very large panel of 110 Mbp covering exonic (~40Mbp) and non-exonic regions (~70Mbp) of interest to enable a wide range of genomic analysis including mutation calling in both coding and non-coding regions, rearrangement detection, viral identification, and copy number analysis. In addition to the whole exome, we extended coverage to include introns, promoters, and untranslated regions of all known driver genes in cancer. We included the entirety of the immunoglobulin loci, T-cell receptor loci and CD3 loci to detect clonotypes and rearrangements. We also included lymphoma-relevant long non-coding RNAs, microRNAs, enhancers, and breakpoint-prone regions. For viral detection, we targeted the genomes of eight cancer-related viruses: Epstein-Barr virus, human papillomavirus, human immunodeficiency virus, hepatitis B, hepatitis C, Kaposi's sarcoma-associated herpesvirus, human T-lymphotropic virus, and Merkel cell polyomavirus. In addition, to enable high resolution identification of copy number variation (CNV) calls, the entire genome was tiled with probes spaced 10kb apart. DNA and RNA were extracted from all tumors and their paired normal samples, prepared into DNA and RNA sequencing libraries and subjected to sequencing on the Illumina platform to a targeted coverage of 150X. Somatic events were identified and further filtered to identify driver events in both coding and non-coding regions. FLs demonstrated a significant degree of genetic heterogeneity with over 100 genes mutated with a frequency of at least 2%. Nearly 100% of FL cases had a mutation in at least one chromatin-modifying gene. The most frequently mutated genes in follicular lymphoma were KMT2D, BCL2, IGLL5 and CREBBP. In addition, we identified frequent mutations in SPEN, BIRC6 and SETD2. To our knowledge, this is the first description of alterations in these genes in FL. Transcriptome analysis indicated a strong correlation between BIRC6 mutations and the previously described immune response 2 signature that is associated with a poor prognosis. We further performed unbiased clustering of genetic alterations in these FL cases. We identified a cluster that was specifically enriched in BCL6 and TP53 alterations and was strongly associated with grade 3 FLs which are predicted to have poorer outcomes with low intensity therapies. We further examined the genetic profiles of 1001 DLBCLs in comparison to this cohort of FLs. Our data indicate a continuum of highly overlapping genetic alterations with DLBCL displaying more complex patterns that included alterations in MYC, TP53 and CDKN2A (mainly copy number losses), indicating shared pathogenetic mechanisms underlying FL and DLBCL, particularly those germinal center B cell origin. Disclosures Koff: Burroughs Wellcome Fund: Research Funding; V Foundation: Research Funding; Lymphoma Research Foundation: Research Funding; American Association for Cancer Research: Research Funding. Leppä:Roche: Honoraria, Research Funding; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bayer: Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen-Cilag: Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees. Gang:ROCHE: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees. Hsi:Abbvie: Research Funding; Eli Lilly: Research Funding; Cleveland Clinic&Abbvie Biotherapeutics Inc: Patents & Royalties: US8,603,477 B2; Jazz: Consultancy. Flowers:AbbVie: Consultancy, Research Funding; Denovo Biopharma: Consultancy; BeiGene: Consultancy, Research Funding; Burroughs Wellcome Fund: Research Funding; Eastern Cooperative Oncology Group: Research Funding; National Cancer Institute: Research Funding; V Foundation: Research Funding; Optimum Rx: Consultancy; Millenium/Takeda: Research Funding; TG Therapeutics: Research Funding; Gilead: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Karyopharm: Consultancy; AstraZeneca: Consultancy; Pharmacyclics/Janssen: Consultancy, Research Funding; Spectrum: Consultancy; Bayer: Consultancy; Acerta: Research Funding; Genentech, Inc./F. Hoffmann-La Roche Ltd: Consultancy, Research Funding. Neff:Enzyvant: Consultancy; EUSA Pharma: Honoraria, Membership on an entity's Board of Directors or advisory committees. Fedoriw:Alexion Pharmaceuticals: Other: Consultant and Speaker. Reddy:Genentech: Research Funding; BMS: Consultancy, Research Funding; Celgene: Consultancy; KITE Pharma: Consultancy; Abbvie: Consultancy. Mason:Sysmex: Honoraria. Behdad:Loxo-Bayer: Membership on an entity's Board of Directors or advisory committees; Thermo Fisher: Membership on an entity's Board of Directors or advisory committees; Pfizer: Other: Speaker. Burton:Bristol-Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel; Celgene: Membership on an entity's Board of Directors or advisory committees; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees. Dave:Data Driven Bioscience: Equity Ownership.

Description: Background: Ivosidenib (Ivo) and enasidenib (Ena) are potent, mutant-specific oral inhibitors of the IDH1 and IDH2 proteins, respectively, and are approved as single agents for the treatment of newly diagnosed (Ivo) and/or relapsed/refractory (Ivo and Ena) AML. When used as single agents, these inhibitors induce differentiation of leukemic blasts, often without a period of bone marrow (BM) aplasia (PMID 28588020, 29860938). A phase 1 study (NCT02632708) examining the safety and efficacy of Ivo or Ena in combination with intensive induction chemotherapy (IDHi/7+3) in newly diagnosed AML with mutant IDH1 or IDH2 (mIDH) has yielded encouraging response rates in preliminary reports (Stein et al. ASH 2018; Abstract 560). The effect of IDHi/7+3 on BM morphology and whether features of differentiation are seen in this context is unknown. Here, we report the clinicopathologic findings in a cohort of patients treated with IDHi/7+3 and describe a distinct pattern of BM response with implications for post-therapy disease monitoring. Methods: Investigators from participating sites for NCT02632708 were invited to contribute cases. 36 patients from 4 sites were included with IRB approval at all sites. For each patient, the diagnostic BM biopsy and aspirate smear (BMBx) and all subsequent BMBx performed until end of induction (EOI) or removal from study were reviewed at individual sites based on consensus criteria. A subset of cases was re-reviewed by all pathologists via photomicrographs and digital whole slide images. Patients were categorized into 3 groups based on their Day 14 (D14) BMBx: 1) Aplasia (D14A = 5% blasts at D14; with morphologic or flow cytometric evidence of blast differentiation at D14 or D21); or 3) Persistent AML (D14P = 〉10% cellular; and 〉5% blasts; and no differentiation or clearance of blasts at D14 or later time points). Clinicopathologic data was collected from the electronic medical record and from the study database. IDH mutation clearance (MC) was defined as a reduction in the mIDH variant allele frequency in BM mononuclear cells to a level below the limit of detection of the assay (0.02-0.04%) for ≥1 on-treatment time point on or after D28 of induction. Results: The cohort included 17 mIDH1 patients who received Ivo and 19 mIDH2 patients who received Ena (Table 1, Fig 1); 1 patient in each treatment group had mIDH1 and mIDH2. In the 31 patients evaluable for response at EOI, 27 achieved CR or CRi/p; 2 MLFS; and 2 SD. Of 29 patients with a morphologic response (CR, CRi/p, MLFS), 19 (66%) were classified as D14A (median 5% cellularity; median

Description: Introduction: Myelodysplastic syndrome (MDS) is a group of heterogeneous diseases characterized by cytologic dysplasia and refractory cytopenias as a result of ineffective hematopoiesis. We have reported that oncofetal protein SALL4 can be used as a prognostic biomarker in MDS disease. SALL4 is a transcription factor that is important for development and embryonic stem cell properties. While SALL4 expression is down-regulated or absent in most adult tissues, SALL4 is re-expressed in various cancers. We have previously reported that aberrant expression of SALL4 can be detected in MDS and AML patients. Studies in murine models, as well as in human samples, have demonstrated that SALL4 is essential for leukemic cell survival and that SALL4 transgenic mice develop an MDS-like phenotype prior to transformation to AML, suggesting that SALL4 can be a driver of MDS/AML pathogenesis. However, SALL4 expression status and related pathway in bone marrow (BM) cells and relationship with somatic gene mutations in MDS patients has not been explored. In this study, we evaluated the expression of SALL4 and related factors using single-cell mass cytometry (CyTOF) and NanoString technology in MDS patients alongside with target sequence for MDS-related mutations. Materials and methods: We evaluated the expression of SALL4 using single-cell mass cytometry (CyTOF) utilizing 28 antibodies including surface lineage markers and intracellular proteins, such as p53, ki67, c-myc and pAKT to identify SALL4 expressed cells and related pathway in bone marrow (BM) for 10 MDS patients. SALL4 expression was also analyzed in formalin-fixed paraffin-embedded (FFPE) 14 patient samples utilizing two SALL4 probes designed for NanoString technology alongside with target sequence for MDS-related mutations. One probe only detects expression of SALL4A, which is full length SALL4, while the other probe can detect both SALL4A as well as its splicing variant SALL4B. We examined the expression of a panel of 17 known SALL4 downstream target genes. Results: First, we assessed an expression level of SALL4 using CyTOF in 10 MDS patients as compared with normal BM samples (N=5). We observed that Lin-CD34+CD38+ progenitor cells in 8 out of the 10 MDS patients had higher SALL4 expression levels, while the progenitor cells of normal BM cells did not express SALL4. Similar results were observed in Lin-CD34+CD38- hematopoietic stem cells, CD11b+ mature myeloid cells, CD19+ B cells, CD235+ erythroid cells. Conversely only 3 MDS patient had weak SALL4 expression in CD3+ T cells. Subsequently, we investigated the correlation with p53, ki67, c-myc and pAKT. SALL4 is only correlated with p53 (P=0.005), while others were not. Next, we also assessed an expression level of SALL4A and SALL4A&B in 14 MDS patient bone marrow (BM) samples using Nanostring nCounter. We observed that 12 out of 14 MDS patients had higher SALL4 expression levels as compared with control normal BM samples (N=3). Next, we evaluated whether MDS patients expressed SALL4A, SALL4B, or both. Of the 14 MDS patients, 8 predominantly expressed SALL4A Of these 8 MDS patients, 5 harbored RNA splicing-related mutations, such as SF3B1 (N=4), U2AF1 (N=1). Only 1 out of 7 patients who predominantly expressed SALL4B demonstrated a splicing related mutation. Subsequently, we investigated the correlation between SALL4 and its known downstream targets. An expression of SALL4A is moderately correlated with CBLb (γ=0.53), CDH1 (γ=0.42) and NAT10 (γ=0.41). The expression of SALLA&B is moderately correlated with NAT10 (γ=0.47) and RUNX1 (γ=0.46). NAT10 (N-acetyltransferase 10) has been reported to promote transcription of RNA polymerase I and is a critical regulator of p53 homeostasis. It was identified to be a potential SALL4 downstream target in our early Chip-seq studies. In the isogenic K562 cell lines with SALL4 overexpression, higher levels of NAT10 were observed, suggesting that NAT10 is one of the downstream targets of SALL4. Conclusions: Our study has demonstrated for the first time that 1) SALL4 was expressed in various MDS BM cells confirmed by CyTOF 2) there are SALL4 splicing variants in MDS patients, particularly with SF3B1 mutations 3) a novel SALL4/NAT10/p53 link has been identified in these MDS patients. Future studies on mechanism(s) and biological role(s) of SALL4 splicing variants in MDS are needed. Disclosures No relevant conflicts of interest to declare.