Citations

Introduction : Daratumumab (DARA) is a human CD38 antibody approved in combination with standard-of-care (SoC) regimens in pts with NDMM who are TIE. DARA-based treatments showed significantly improved progression-free survival (PFS) in pts with TIE NDMM in ongoing phase 3 studies ALCYONE (DARA + bortezomib/melphalan/prednisone [D-VMP] vs VMP) and MAIA (DARA + lenalidomide/dexamethasone [D-Rd] vs Rd continuous). An NMA allows estimation of the relative efficacy of regimens not compared in head-to-head trials. A previous NMA examined D-VMP and D-Rd vs comparators (Facon T et al., EHA 2019), excluding the SWOG S0777 study (bortezomib/lenalidomide/dexamethasone [VRd]; Durie BG, et al. Lancet 2017) as it enrolled both transplant-eligible (TE) and TIE pts, and data for pts who are TIE only (~50% [aged ≥65 y and frail]) were unavailable. In this NMA, D-Rd and D-VMP had the highest probabilities of being more effective than reference treatment Rd continuous in terms of PFS. Recently, VRd received EMA approval for treatment of TIE NDMM based on SWOG S0777, but results specific to TIE pts are still unavailable. Recent NMAs of TIE pts (Blommestein HM et al., Haematologica, 2019; Weisel et al., EHA 2019; Cao Y et al., Clin Lymphoma Myeloma Leuk, 2019) have included data from the the intent-to-treat (ITT) population of SWOG S0777, though its inclusion violates the similarity assumption. Here, we present a sensitivity analysis of the previously-conducted NMA including all pts who received VRd in SWOG S0777 for a comprehensive view of the comparative effectiveness of DARA-based treatments in TIE NDMM. Methods: VRd was included as part of a sensitivity analysis of the previous NMA based on the ITT population, reporting PFS and overall survival (OS). The Guyot method was used to estimate OS hazard ratios (HRs) for pts aged ≥65 y (proxy for TIE) from SWOG S0777 (Durie BG et al., ASH 2018). Median follow-up in ALCYONE and MAIA was 27.8 months and 28.0 months, respectively. Based on a systematic literature review conducted through January 2019, both PFS and OS were extracted and synthesized in Bayesian NMAs. Choice of fixed- or random-effects (FE or RE) model was based on lowest deviance information criterion (DIC) and/or presence of heterogeneity in the network. Rd continuous was selected as reference, as it was commonly included in guidelines across regions. For PFS and OS, HR <1 indicates the comparison is not in favor of Rd continuous. In addition to the previous NMA, we also report an NMA sensitivity analysis including only comparators approved by the EMA that are relevant for the European, Middle East and/or Africa (EMEA) region (EMEA NMA). Results: Global NMA: RE model was used for both PFS and OS. Compared with Rd continuous, the PFS HR for VRd in the sensitivity analysis was 0.74 (95% credible interval [CrI], 0.42-1.30), which was similar to SWOG S0777 (0.71; [96% Wald confidence interval [CI], 0.56-0.91]) and higher than HRs for D-Rd (0.55; 95% CrI, 0.31-0.97) and D-VMP (0.58; 95% CrI, 0.20-1.62; Table). For OS, the SWOG S0777 HR estimated by Guyot algorithm for pts aged ≥65 y was 0.80 (95% CI, 0.56-1.16). Compared with Rd continuous, the OS HR for VRd in the sensitivity analysis was 0.80 (95% CrI, 0.51-1.26), which was similar to SWOG S0777 and higher than D-Rd (0.78; 95% CrI, 0.51-1.18). EMEA NMA: FE model was used for both PFS and OS. Compared with Rd continuous, the PFS HR for VRd in the sensitivity analysis was 0.74 (95% CrI, 0.60-0.92), which was higher than HRs of D-Rd (0.55; 95% CrI, 0.43-0.71) and D-VMP (0.64; 95% CrI, 0.41-1.02). Compared with Rd continuous, the OS HR for VRd in the sensitivity analysis was 0.80 (95% CrI, 0.55-1.17), which was higher than for D-Rd (0.78; 95% CrI, 0.56-1.09). These results are consistent with the Global NMA, but differ slightly as the EMEA NMA has fewer evidence-loops (only EMEA SoC regimens were included). Conclusions: This study demonstrated favorable efficacy outcomes for DARA-based regimens vs other relevant frontline options, such as VRd, for pts with NDMM who are TIE. Limitations of the sensitivity analysis include lack of comparative trial data and demographic differences between pts from SWOG S0777 and trials of frontline MM treatments for pts who are TIE included in our network. The majority of SWOG S0777 pts are TE (<65 y), who often have better prognoses than TIE pts (≥65 y), and thus violates the similarity assumption of NMAs. However, DARA-based regimens still showed a comparative clinical advantage. Disclosures Facon: Takeda: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Sanofi: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees. San-Miguel:Amgen, Bristol-Myers Squibb, Celgene, Janssen, MSD, Novartis, Roche, Sanofi, and Takeda: Consultancy, Honoraria. Usmani:Amgen, Bristol-Myers Squibb, Celgene, Janssen, Merck, SkylineDX, Takeda: Other: Consultant/Advisor; Amgen Array Biopharma, Bristol-Myers Squibb, Celgene, Janssen, Merck, Pharmacyclics, Sanofi, Takeda: Other: Research Grant; Amgen, Celgene, Janssen, Sanofi, Takeda: Speakers Bureau. Dimopoulos:Sanofi Oncology: Research Funding. Kumar:Janssen: Consultancy, Research Funding; Takeda: Research Funding; Celgene: Consultancy, Research Funding. Mateos:Adaptive: Honoraria; EDO: Membership on an entity's Board of Directors or advisory committees; Pharmamar: Membership on an entity's Board of Directors or advisory committees; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: 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; GSK: Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees. Cavo:Janssen, Celgene, Amgen, Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene, Janssen, Amgen, BMS, Abbvie, Takeda: Honoraria; Janssen, Celgene: Other: Travel Accommodations; Janssen, Celgene: Speakers Bureau. Heeg:Ingress-Health: Employment. Van Beekhuizen:Ingress-health: Consultancy. Pisini:Janssen: Employment, Equity Ownership. Nair:Janssen: Employment, Equity Ownership. Lam:Janssen: Employment, Equity Ownership. Slavcev:Janssen: Employment, Equity Ownership. He:Janssen: Employment, Equity Ownership.

Abstract Patients with glioblastoma (GBM) have a median survival of 15 months despite aggressive treatment. Immunotherapies such as dendritic cell (DC) vaccines have modest clinical efficacy in small clinical trials. Treatment-related pseudo-progression confounds outcome assessment by MRI, particularly in patients receiving immunotherapy. Thus, there is a need for additional non-invasive methods to monitor treatment response. Extracellular vesicles (EVs), especially plasma exosomes, contain tumor-specific microRNA (miRNA) cargo that could serve as a liquid biopsy to distinguish true progression from treatment-related pseudo-progression. Plasma exosomes were isolated by serial density gradient ultracentrifugation from 20 newly diagnosed GBM patients enrolled in a clinical trial of allogeneic tumor lysate-pulsed autologous DC vaccination. Short non-coding RNA sequencing and bioinformatics analysis was performed for each patient at three time points (TP): pre-vaccine (TP1), post-initial vaccine (TP2), and at end of treatment (TP3). miRNA expression analysis revealed a total of 14 upregulated and 12 downregulated miRNAs across time points (p-value < 0.05, |logFC| >1), few of which have been previously reported to be differentially expressed in GBM. Interestingly, patients’ miRNA profile expression differed more at the beginning of treatment (e.g. TP1-vs-TP2) and at subsequent time points (e.g. TP2-vs-TP3). Ingenuity Pathway Analysis is in progress to identify pathways associated with immunotherapy treatment response in malignant gliomas. In conclusion, miRNA sequencing from GBM patients’ plasma exosomes enrolled in our DC clinical trial shows marked differential miRNA expression between time points. These results suggest that as patients progress through treatment, consistent differences in plasma exosomal miRNA expression profile can be identified that could be utilized as predictors of treatment response. Thus, plasma EVs may serve as a robust platform to monitor treatment outcome.

Abstract Abstract SCI-3 The processes that lead to the susceptibility of post-mitotic tissues to diseases of aging are poorly understood, but mitochondria are considered a key regulator. SIRT3 is mitochondrial sirtuin, a member a family of NAD+-dependent deacetylases. We have previously shown that increased levels of NAD+ in mitochondria promote cell survival in a SIRT3-dependent manner, but how this protection is mediated is unknown. Here we show that mitochondrial NAD+ levels decline dramatically with age and that SIRT3 is a critical component and regulator of the mitochondrial transition pore (MTP). Mice lacking SIRT3 exhibit hyperacetylation of the MTP with age, and as a result, develop multiple defects in post-mitotic tissues as they age, including mitochondrial defects, susceptibility to cardiac failure, and learning and memory deficits. In a mouse model of Alzheimer's disease (AD), SIRT3 knockout mice show striking phenotypes including small size, kyphosis, and a markedly reduced lifespan. Similar to mice, human brain samples show that acetylation of the MTP increases with age and with AD. These findings indicate that declining NAD levels with age lead to memory deficits and accelerate age-related diseases in post-mitotic tissues due to a decline in SIRT3 activity and unscheduled opening of the MTP. Disclosures: Sinclair: GlaxoSmithKline: Consultancy, Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties.

Abstract Long non-coding RNAs (lncRNA) are key regulatory RNAs that do not code for protein. Recently lncRNAs have been recognized as key regulators of gene expression and chromatin organization. Although, deregulation of lncRNAs such as HOTAIR, MALAT1 and H19 has been reported in solid cancers, role of lncRNAs in lymphoma or other hematologic malignancies is not known. The aim of this study is to identify lymphoma-associated lncRNAs and elucidate their role in disease pathogenesis. Next generation RNA-sequencing and validation studies were carried out on mantle cell lymphoma (MCL) patient samples along with normal controls. As a result, hundreds of lncRNAs were found overexpressed in the MCL samples as compared with normal B cells, including RP11-24J23.2 (50 fold), RP11-12A2.3 (36 fold) and DLEU7-AS1 (19 fold). Quantitative RT-PCR (QRT-PCR) confirmed higher expression of RP11-24J23.2, RP11-12A2.3, and DLEU7-AS1 in MCL patient samples as compared to normal B cells. To investigate the biological significance of lncRNAs in MCL cells, we overexpressed RP11-24J23.2, RP11-12A2.3, and DLEU7-AS1 lncRNAs and analyzed effects on cell proliferation and apoptosis. To achieve overexpression lncRNAs, RP11-24J23.2, RP11-12A2.3, and DLEU7-AS1 were cloned individually in expression pcDNA3.1 generating constructs: pcDNA3RP11-24J23.2, pcDNA3RP11-12A2.3 and pcDNA3DLEU7-AS1and then transfected into MCL cell lines along with pcDNA3.1. QRT-PCR revealed effective overexpression (~100 fold increase over baseline) for each transfected lncRNAs construct in Granta and Mino cells. Analysis of proliferation and survival showed that overexpressing RP11-24J23.2, RP11-12A2.3 or DLEU7-AS1 promotes cell proliferation and survival in these cells as compared to the vector controls. Most of the lncRNAs found so far have been linked to the transcriptional regulation of the target genes through their association with chromatin remodeling factors such as Polycomb Repressive Complex 2 (PRC2). To identify the functional relevance of RP11-24J23.2, RP11-12A2.3, and DLEU7-AS1 lncRNAs, we examined the binding of the lymphoma specific lncRNAs with PRC2 complex, by performing RNA immunoprecipitation (RNA-IP) using specific antibodies to EZH2, EED and SUZ12. The RNA-IP results demonstrate high affinity binding of all three lncRNAs with SUZ12 and EED but a weak binding with EZH2. Furthermore, RNA-IP using antibody to histone 3-lysine 27 trimethylation (H3K27me3), a suppressive histone mark associated with PRC2 complex, also showed efficient binding with RP11-24J23.2, RP11-12A2.3, and DLEU7-AS1. These results suggest that RP11-24J23.2, RP11-12A2.3, and DLEU7-AS1 lncRNAs can directly associated with PRC2 complex at chromatin. To understand the mechanism of increased cell growth after overexpression of lncRNAs, RP11-24J23.2, RP11-12A2.3 or DLEU7-AS1, we analyzed expression level of important genes signature of MCL pathogenesis that include cyclin D1, cyclin D3, c-Myc, P14, and SOX11, a member of the group C SOX (SRY-related HMG-box) transcription factor family. Our results demonstrate that overexpression of lncRNAs RP11-24J23.2, RP11-12A2.3 or DLEU7-AS1 enhanced the levels of cyclin D1 (>2 fold) mRNA without any impact on cyclin D3 or c-Myc transcript levels. In contrast overexpression of RP11-24J23.2, RP11-12A2.3 or DLEU7-AS1 lncRNAs decreased SOX11 (0.08, 0.1 and 0.06 respectively) and P14 (0.06, 0.7 and 0.40 respectively) mRNA expression in Mino cells. To gain understanding of the mechanism involved in the suppression of SOX11 by the lncRNAs, we performed Chromatin immunoprecipitation assays with EZH2, EED and SUZ12 antibodies on Mino cells transfected with pcDNA3RP11-24J23.2, pcDNA3RP11-12A2.3 and pcDNA3DLEU7-AS1 or vector control. The data showed that overexpression of RP11-12A2.3 and DLEU7-AS1 significantly increased the binding of EED and to a lesser extent of EZH2 to SOX11 promoter while the binding of SUZ12 to SOX11 promoter was not changed as compared to vector alone. In conclusion, our results imply that lncRNAs are overexpressed in the MCL. Moreover, lymphoma associated lncRNAs (RP11-24J23.2, RP11-12A2.3 and DLEU7-AS1) regulate SOX11 expression via PRC2 complex contributing towards growth of MCL cells. Specific nature of lncRNAs found in lymphoma samples suggests that lncRNAs can be used as potential biomarkers for mantle cell lymphoma. Disclosures No relevant conflicts of interest to declare.

Abstract Abstract 132 Multiple myeloma (MM), an incurable neoplasia of terminally differentiated plasma cells, are critically dependent on their interactions with bone marrow stromal cells (BMSC) for essential survival signals, growth and immunosuppressive factors. Very little is known about the specific BM cell type or the molecular elements in these interactions, an understanding of which could provide novel targets that could be interdicted to enhance conventional chemotherapy. A potential MM surface protein that could be involved in these interactions is CD28, based on its known pro-survival role in T cells. Clinical studies have shown that expression of CD28 in multiple myeloma highly correlates (p=0.006) with myeloma tumoral expansion. Moreover, CD28+ MM cells invariably express the CD28 ligand CD86. A survival role for MM-CD28 might involve interactions with BM cells that express B7 (CD80/CD86) such as dendritic cells (DCs, that are known to be closely associated with MM cells in the BM) or with CD86+ MM cells themselves. We had previously shown (ASH2008, #I-769) that blocking CD28-CD86 interactions between myeloma cells with high affinity B7 ligand CTLA4Ig (Abatacept®) sensitized myeloma cells to chemotherapy. Now we show that myeloma cells co-cultured with myeloid DCs in vitro derive both direct and indirect survival signals from DCs, and this can be partially blocked by commercially available reagents. Our data show that flow cytometric analysis of mononuclear cells (MNC) from BM aspirates of myeloma patients with increased CD138+ plasma cell populations (9-58%), show an increased CD11b+ (myeloid) population (20-37%) as well, which is in contrast to healthy transplant donor controls (12-15% CD11b+, 4–6% CD138+). Moreover, a larger fraction (11-47%) of the myeloma CD138+ plasma cells expressed CD28 compared to healthy control (3.3-7.7%). Also, when we analyzed gene expression datasets (NCBI #GSE5900 and GSE4204) from plasma cells (PC) of normal donors, monoclonal gammopathy of undetermined significance (MGUS), smoldering myeloma (SM) and newly diagnosed multiple myeloma (MM), we found a progressive increase in patients showing CD28 expression with increasing severity of disease (normal<MGUS<SM<MM) (Fig 1A). When we sorted the highest scoring MM group (n=538) into 8 genetic subgroups as defined earlier, CD28 expression was found to peak in the MF subgroup (typically associated with poor survival in myeloma patients) (Zhan et al. 2006, Blood 108, pp. 2020) relative to total population (p<0.0001) (Fig 1B). Antibody mediated activation of MM-CD28 over 48 hrs increased viability of myeloma cell line MM.1S cultured under serum starvation (3.7%) or with drugs ATO (1.9%), melphalan (18%) or dexamethasone (3.3%) to 66%, 21%, 33% and 11% respectively. Viability of MM.1S cells or primary CD138+ plasma cells (isolated from myeloma BM aspirates) cultured under serum starvation was enhanced >3 fold (p<0.001) when co-cultured with monocyte derived DCs, and in MM.1S this was partially reversed when either MM-CD28 or DC-B7 was blocked (Fig 2). Similar protection of MM.1S was also observed against a gradient of dexamethasone or melphalan. CD28 activation was accompanied by rapid tyrosine phosphorylation of CD28, association of p85 (PI3K), activation of Vav-1 and increase in CD28 associated tyrosine kinase activity, as shown by immunoprecipitation, western and kinase activity assays. We had previously shown that MM-CD28 interaction drive DC production of pro-survival factor IL-6 and immunosuppressive factor IDO via DC-B7 “backsignaling” (ASH2008 #I-769). Now we show that MM induced DC production of IL-6 (8 ng/ml) was partially inhibited in presence of CD28 blocking αCD28(Fab) fragments (3 ng/ml) or with protein kinase C (PKC) inhibitor Bisindolylmaleimide-I (2.1ng/ml). Activity of the immunosuppressive enzyme IDO in these co-cultures was completely inhibited in the presence of a novel IDO inhibitor from Incyte corporation, and this helped partially reverse IDO mediated suppression of T-cell proliferation in proliferation assays using co-culture supernatants. In conclusion, our data characterizes CD28-B7 pathway and DCs in the BM as vital for myeloma survival and also as possible targets to include in future strategies in the treatment of myeloma. FIGURE 1 FIGURE 1. FIGURE 2 FIGURE 2. Disclosures: Boise: University of Chicago: Patents & Royalties.

AbstractMAPK pathway activation has been recurrently observed in desmoplastic infantile ganglioglioma/astrocytoma (DIG/DIA) with reported disproportionally low mutation allele frequencies relative to the apparent high tumor content, suggesting that MAPK pathway alterations may be subclonal. We sought to expand the number of molecularly profiled cases and investigate if tumor cell composition could account for the observed low mutation allele frequencies. Molecular (targeted neuro-oncology next-generation sequencing/RNA sequencing and OncoScan microarray) and immunohistochemical (CD68-PGM1/CD163/CD14/CD11c/lysozyme/CD3/CD20/CD34/PD-L1) studies were performed in 7 DIG. Activating MAPK pathway alterations were identified in 4 (57%) cases: 3 had a BRAF mutation (V600E/V600D/V600_W604delinsDQTDG, at 8%–27% variant allele frequency) and 1 showed a TPM3-NTRK1 fusion. Copy number changes were infrequent and nonrecurrent. All tumors had at least 30% of cells morphologically and immunophenotypically consistent with microglial/macrophage lineage. Two subtotally resected tumors regrew; 1 was re-excised and received adjuvant treatment (chemotherapy/targeted therapy), with clinical response to targeted therapy only. Even with residual tumor, all patients are alive (median follow-up, 83 months; 19–139). This study further supports DIG as another MAPK pathway-driven neuroepithelial tumor, thus expanding potential treatment options for tumors not amenable to surgical cure, and suggests that DIG is a microglia/macrophage-rich neuroepithelial tumor with frequent low driver mutation allele frequencies.

Insulin resistance associates with increased risk for cognitive decline and dementia; however, the underpinning mechanisms for this increased risk remain to be fully defined. As insulin resistance impairs mitochondrial oxidative metabolism and increases ROS in skeletal muscle, we considered whether similar events occur in the brain, which — like muscle — is rich in insulin receptors and mitochondria. We show that high-fat diet–induced (HFD-induced) brain insulin resistance in mice decreased mitochondrial ATP production rate and oxidative enzyme activities in brain regions rich in insulin receptors. HFD increased ROS emission and reduced antioxidant enzyme activities, with the concurrent accumulation of oxidatively damaged mitochondrial proteins and increased mitochondrial fission. Improvement of insulin sensitivity by both aerobic exercise and metformin ameliorated HFD-induced abnormalities. Moreover, insulin-induced enhancement of ATP production in primary cortical neurons and astrocytes was counteracted by the insulin receptor antagonist S961, demonstrating a direct effect of insulin resistance on brain mitochondria. Further, intranasal S961 administration prevented exercise-induced improvements in ATP production and ROS emission during HFD, supporting that exercise enhances brain mitochondrial function by improving insulin action. These results support that insulin sensitizing by exercise and metformin restores brain mitochondrial function in insulin-resistant states.

Abstract Objectives To develop and replicate, using data-driven methods, a novel classification system in Takayasu’s arteritis based on distribution of arterial lesions. Methods Patients were included from four international cohorts at major academic centres: India (Christian Medical College Vellore); North America (National Institutes of Health, Vasculitis Clinical Research Consortium and Cleveland Clinic Foundation). All patients underwent whole-body angiography of the aorta and branch vessels, with categorization of arterial damage (stenosis, occlusion or aneurysm) in 13 territories. K-means cluster analysis was performed to identify subgroups of patients based on pattern of angiographic involvement. Cluster groups were identified in the Indian cohort and independently replicated in the North American cohorts. Results A total of 806 patients with Takayasu’s arteritis from India (n = 581) and North America (n = 225) were included. Three distinct clusters defined by arterial damage were identified in the Indian cohort and replicated in each of the North American cohorts. Patients in cluster one had significantly more disease in the abdominal aorta, renal and mesenteric arteries (P &lt; 0.01). Patients in cluster two had significantly more bilateral disease in the carotid and subclavian arteries (P &lt; 0.01). Compared with clusters one and two, patients in cluster three had asymmetric disease with fewer involved territories (P &lt; 0.01). Demographics, clinical symptoms and clinical outcomes differed by cluster. Conclusion This large study in Takayasu’s arteritis identified and replicated three novel subsets of patients based on patterns of arterial damage. Angiographic-based disease classification requires validation by demonstrating potential aetiological or prognostic implications.

Background: Open surgical closure and small-bore suture-based preclosure devices have limitations when used for transcatheter aortic valve replacement, percutaneous endovascular abdominal aortic aneurysm repair, or percutaneous thoracic endovascular aortic aneurysm repair. The MANTA vascular closure device is a novel collagen-based technology designed to close large bore arteriotomies created by devices with an outer diameter ranging from 12F to 25F. In this study, we determined the safety and effectiveness of the MANTA vascular closure device. Methods and Results: A prospective, single arm, multicenter investigation in patients undergoing transcatheter aortic valve replacement, percutaneous endovascular abdominal aortic aneurysm repair, or thoracic endovascular aortic aneurysm repair at 20 sites in North America. The primary outcome was time to hemostasis. The primary safety outcomes were accessed site-related vascular injury or bleeding complications. A total of 341 patients, 78 roll-in, and 263 in the primary analysis cohort, were entered in the study between November 2016 and September 2017. For the primary analysis cohort, transcatheter aortic valve replacement was performed in 210 (79.8%), and percutaneous endovascular abdominal aortic aneurysm repair or thoracic endovascular aortic aneurysm repair was performed in 53 (20.2%). The 14F MANTA was used in 42 cases (16%), and the 18F was used in 221 cases(84%). The mean effective sheath outer diameter was 22F (7.3 mm). The mean time to hemostasis was 65±157 seconds with a median time to hemostasis of 24 seconds. Technical success was achieved in 257 (97.7%) patients, and a single device was deployed in 262 (99.6%) of cases. Valve Academic Research Consortium-2 major vascular complications occurred in 11 (4.2%) cases: 4 received a covered stent (1.5%), 3 had access site bleeding (1.1%), 2 underwent surgical repair (0.8%), and 2 underwent balloon inflation (0.8%). Conclusions: In a selected population, this study demonstrated that the MANTA percutaneous vascular closure device can safely and effectively close large bore arteriotomies created by current generation transcatheter aortic valve replacement, percutaneous endovascular abdominal aortic aneurysm repair, and thoracic endovascular aortic aneurysm repair devices. Clinical Trial Registration: URL: https://www.clinicaltrials.gov . Unique identifier: NCT02908880.

29 Background: CRS-207 is a live, attenuated, double-deleted Listeria monocytogenes (LADD) engineered to stimulate immune response to mesothelin. In a phase I trial of 60 MPM patients, 34% of subjects had tumor reduction (range -1 to -47%) following 2 doses of CRS-207 alone. In KEYNOTE-028 pembro showed activity in PDL1+ (≥1% by IHC) MPM, with an objective response rate (ORR) of 20% (5/25) and stable disease in 52% of subjects who had failed or did not receive chemotherapy. Subsequent studies of pembro have shown similar results in MPM. Results from a pre-clinical murine lung tumor model (CT26hMeso) showed anti-PD-1 enhanced LADD-induced tumor response. The study described here evaluated the efficacy of combination therapy of CRS-207/pembro. Methods: Adults with epithelial/biphasic MPM, ≤2 prior lines, progression on pemetrexed and platinum-based therapy, and no prior immunotherapies were enrolled. CRS-207/pembro were administered IV Q3W for 4 cycles, after which pembro continued Q3W and CRS-207 changed to Q6W. Response was assessed Q6W by modified RECIST for MPM (Byrne and Nowak, 2004). The primary endpoint was ORR; secondary endpoints included DOR, disease control rate (DCR), progression-free survival (PFS) and overall survival. Pre- and on-treatment blood and tumor samples were collected. Shedding and blood clearance of CRS-207 were evaluated. Results: 9/10 subjects were evaluable for response. No responses were observed; DCR was 11% (1/9 with SD) and PFS ranged from 3.4 to 8.9 weeks. Most common treatment related adverse events were chills, pyrexia and nausea. 3/10 subjects evaluated were PDL-1 negative by IHC. Of 6 subjects who underwent clearance and shedding evaluation, CRS-207 was detected in blood in 1 at 18-24 hrs after the first CRS-207 dose and cleared by the next evaluation at Day 4; shedding samples (urine, fecal, and saliva) tested negative. Conclusions: The toxicity profile of CRS-207/pembro combination was consistent with the safety profile of each component alone. No evidence of clinical activity was observed. Based on the results and an overall evaluation of the program, the clinical development of CRS-207 was discontinued. (NCT01675765) (NCT02054806). Clinical trial information: NCT03175172.