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Background: Randomized controlled trials leading to the approval of apixaban and rivaroxaban for venous thromboembolism (VTE) did not include patients with UE-DVT. Limited observational data has been published on outcomes in this setting and no direct comparison to traditional anticoagulation has been performed. Objective: Evaluate the safety and effectiveness of rivaroxaban and apixaban for the treatment of acute UE-DVT compared to low-molecular weight (LWMH) and warfarin. Methods: Consecutive patients with VTE were enrolled into the Mayo Clinic VTE Registry, between March 1, 2013 and July 22, 2019, were followed prospectively. Clinical, demographic and imaging data were collected at the time of study recruitment. Patients with a diagnosis of acute UE-DVT who received either rivaroxaban, apixaban, LMWH or warfarin within the first 14 days after diagnosis and who completed at least 3 months of anticoagulant therapy or had an outcome event in that period were included into the analysis. Recurrent VTE, major bleeding, clinical relevant non-major bleeding (CRNMB), and death were assessed at 3 months, in person whenever feasible, or by mailing a written questionnaire or a scripted phone interview. The study was approved by Mayo Clinic Institutional Review Board. Results: One hundred and thirty-four patients with acute UE-DVT were included. Forty-one were treated with apixaban, 32 with rivaroxaban, and 61 with LWMH and/or warfarin. The mean age was 58.3 years, mean BMI was 28.2, and 59% were male (Table 1). Patients treated with LMWH / warfarin were older (61.3 vs 55.8, p=0.04) and had a lower BMI (27.1 vs 29.0, p=0.0496). Twenty-six (19%) patients had catheter-associated UE-DVT, 93 (69.4%) had a diagnosis of malignancy, and 16 (11.9%) had concurrent pulmonary embolism, which were similar between groups. More patients on apixaban /rivaroxaban were receiving chemotherapy (53.4% vs 47.5%, p=0.04) and had recent surgery (13.7% vs 3.3%, p=0.04) compared to LMWH / warfarin. At 3 months of follow up, 1 recurrent VTE occurred in patients treated with LMWH /warfarin and none of those treated with apixaban /rivaroxaban (p=0.27). Major bleeding occurred in 2 patients treated with LMWH /warfarin and in none of those treated with apixaban /rivaroxaban (p=0.12). CRNMB occurred in 1 patient treated with LWMH /warfarin and 5 patients treated with apixaban / rivaroxaban (p=0.15). Two of the CRNMBs occurred with rivaroxaban and 3 occurred with apixaban. Death occurred in 5 patients treated with LMWH /warfarin and in none of the apixaban /rivaroxaban treated patients (p=0.01). Conclusion: This single institution prospective study adds to the limited experience with apixaban and rivaroxaban for acute UE-DVT. Treatment of UE-DVT with rivaroxaban and apixaban appears to be as safe and effective as LMWH/warfarin after 3 months of anticoagulation. Disclosures McBane: BMS: Research Funding.

Background: Diffuse large B-cell lymphomas (DLBCL) are a heterogeneous group of aggressive B-cell non-Hodgkin lymphomas (NHL). Primary mediastinal B-cell lymphoma (PMBCL) is often grouped and managed as DLBCL, yet PMBCL is biologically and clinically different. Although about two-third of patients are cured with initial therapy, those who are refractory or progress within the first two years do poorly and will die from their disease. There is an unmet need for effective therapeutic approaches in this patient population. Evasion of the host immune responses is an important mechanism for inducing resistance to cancer therapy. Strategies to block molecular and cellular mediators of cancer induced immunosuppression such as programmed death -1 receptor (PD-1) have been explored. Targeting PD-1 immune checkpoints has the potential to play a major role in cancer therapy by reversing tumor immune escape. Trials using PD-1 blockers in advanced hematological malignancies demonstrated remarkable activity in Hodgkin lymphoma. Unfortunately, results in the DLBCL cohort with nivolumab were marginal and short lived. A phase 1b trial in heavily pre-treated relapsed/refractory (RR) PMBCL using pembrolizumab (a PD-1 blocker) showed that it was safe and active with an ORR of 41%. In recent years, several signaling pathways implicated in DLBCL pathogenesis have been targeted, including the PI3K-AKT-mTOR pathway. Copanlisib, a pan-PI3K inhibitor, with particularly potent PI3K-α/PI3K-δ inhibition, showed activity in both indolent and aggressive NHL, with a safer toxicity profile than the FDA-approved agent idelalisib. In a preclinical DLBCL mouse model, treatment with copanlisib resulted in effective down regulation of tumor‐infiltrating T-regulatory cells (Tregs). In the same model, copanlisib, when combined with a surrogate anti‐mouse PD‐1, showed in vivo responses in 75% vs 0% in the monotherapy groups. These data support the rational for the combination of copanlisib and checkpoint blockade in DLBCL. We developed a phase 2 prospective study with two RR cohorts (DLBCL and PMBCL), treated with the combination of copanlisib and nivolumab. Study Design: copanlisib hydrochloride 60 mg is given IV on days 1, 8 and 15 of cycles 1-8 and days 1 and 15 of subsequent cycles. Nivolumab 240 mg IV is given on days 1 and 15 of cycles 1-8 and 480 mg on day 1 of subsequent cycles. Cycles repeat every 28 days for up to 2 years in the absence of disease progression or unacceptable toxicity. Copanlisib dose will be determined using a safety cohort in 6 patients. The primary outcome is to assess ORR defined as complete and partial responses (CR+PR). Secondary outcomes are to evaluate safety of the combination; to assess progression free survival (PFS), duration of response (DOR), CR rate, and overall survival (OS). Exploratory objectives are to characterize the effects of the copanlisib and nivolumab combination regimen on tumor cells, tumor microenvironment and the immune response in RR DLBCL and PMBCL. We will also do Lymph3CX assay as an integrated biomarker to distinguish between DLBCL and PMBCL. Key inclusion criteria: adult patients with RR DLBCL and PMBCL who have measurable disease with at least one lesion that is >15mm in the longest diameter on cross-sectional imaging; After failure of ASCT or after failure of frontline therapy in subjects who declined or are not ASCT candidates; and have appropriate organ function. Key exclusion criteria: High grade B-cell lymphomas; Active, known or suspected autoimmune disease or patients on any prohibited therapies; History of active CNS involvement or leptomeningeal involvement This study is expected to enroll a maximum of 96 (6 safety cohort, 44 DLBCL and 46 PMBCL) evaluable patients. We anticipate accruing 10 additional patients to account for ineligibility, cancellation, or other reasons. Therefore, the study is expected to accrue a maximum of 106 patients. The largest success proportion where the proposed treatment regimen would be considered ineffective in DLBCL is 25% and 30% in PMBCL. The smallest success proportion that would warrant subsequent studies with the proposed regimen is 45% in DLBCL and 50% in PMBCL. This design has a 90% power with a 1-sided 10% level test. This study is conducted through NCI-CTEP (NCI Protocol #10193; NCT03484819) and is funded by Bayer. The study is to open in fall of 2019 at 11 ECTCN sites, and is available to interested sites to join in. Figure. Disclosures Bennani: Kite Pharma: Other: Advisory board; Seattle Genetics: Other: Advisory board; Purdue Pharma: Other: Advisory board; Seattle Genetics: Other: Advisory board; Bristol-Myers Squibb: Research Funding; Purdue Pharma: Other: Advisory board; Adicet Bio: Other: Advisory board; Adicet Bio: Other: Advisory board; Purdue Pharma: Other: Advisory board; Bristol-Myers Squibb: Research Funding; Bristol-Myers Squibb: Research Funding; Kite Pharma: Other: Advisory board; Kite Pharma: Other: Advisory board; Seattle Genetics: Other: Advisory board; Adicet Bio: Other: Advisory board. Nowakowski:Celgene: Consultancy, Research Funding; Selvita: Membership on an entity's Board of Directors or advisory committees; NanoString: Research Funding; MorphoSys: Consultancy, Research Funding; Genentech, Inc.: Research Funding; F. Hoffmann-La Roche Ltd: Research Funding; Curis: Research Funding; Bayer: Consultancy, Research Funding. Rimsza:NanoSting: Patents & Royalties: Named inventor on a patent licensed to NanoSting [Institution]. Ansell:Bristol-Myers Squibb: Research Funding; Mayo Clinic Rochester: Employment; Seattle Genetics: Research Funding; Seattle Genetics: Research Funding; Regeneron: Research Funding; Bristol-Myers Squibb: Research Funding; LAM Therapeutics: Research Funding; Regeneron: Research Funding; Regeneron: Research Funding; Mayo Clinic Rochester: Employment; Affimed: Research Funding; Bristol-Myers Squibb: Research Funding; Seattle Genetics: Research Funding; Trillium: Research Funding; Regeneron: Research Funding; Bristol-Myers Squibb: Research Funding; LAM Therapeutics: Research Funding; Regeneron: Research Funding; Bristol-Myers Squibb: Research Funding; Trillium: Research Funding; Trillium: Research Funding; Regeneron: Research Funding; Mayo Clinic Rochester: Employment; Trillium: Research Funding; LAM Therapeutics: Research Funding; Mayo Clinic Rochester: Employment; Affimed: Research Funding; LAM Therapeutics: Research Funding; Regeneron: Research Funding; LAM Therapeutics: Research Funding; Bristol-Myers Squibb: Research Funding; Trillium: Research Funding; Affimed: Research Funding; Seattle Genetics: Research Funding; LAM Therapeutics: Research Funding; Bristol-Myers Squibb: Research Funding; Trillium: Research Funding; LAM Therapeutics: Research Funding; Mayo Clinic Rochester: Employment; Seattle Genetics: Research Funding; Trillium: Research Funding; Mayo Clinic Rochester: Employment; Affimed: Research Funding; Trillium: Research Funding; Mayo Clinic Rochester: Employment; Mayo Clinic Rochester: Employment; Mayo Clinic Rochester: Employment; Seattle Genetics: Research Funding; Affimed: Research Funding; Trillium: Research Funding; Seattle Genetics: Research Funding; Affimed: Research Funding; Seattle Genetics: Research Funding; Regeneron: Research Funding; Affimed: Research Funding; LAM Therapeutics: Research Funding; Bristol-Myers Squibb: Research Funding; Affimed: Research Funding; LAM Therapeutics: Research Funding; Bristol-Myers Squibb: Research Funding; Affimed: Research Funding; Regeneron: Research Funding; Seattle Genetics: Research Funding.

Introduction There have been few recent therapeutic advances in T-acute lymphoblastic leukemia/lymphoma (T-ALL/LBL), a rare and aggressive malignancy. Intensive chemotherapy +/- allogeneic transplantation (AlloHCT) can effect cure, realized by only a minority of adults. In distinction to B-ALL, there have been no safe/effective targeted therapies developed in T-ALL/LBL. We therefore performed a focused tissue array to identify novel tumor proteins, including CCR4; evaluated together with established immunophenotypic (IP) T-ALL/LBL subtypes [early-T-precursor (ETP), early non-ETP (Pre/Pro-T), common & late thymocyte]. We evaluated the clinical phenotype and outcome together with clinical and epidemiologic data in patients diagnosed at the 3-site Mayo Clinic Cancer Center (MCCC: Rochester, MN; Phoenix, AZ; and Jacksonville, FL). Methods Following IRB approval, we identified 50 consecutive T-ALL/LBL patients from 1997 -2019 diagnosed at the 3-site MCCC. Available remnant leukemia/lymphoma paraffin blocks were identified (n=28). Using immunohistochemistry (IHC) we evaluated expression of leukemic antigens of interest (CCR4, CD47, BCL2, BCL6, PD-L1, CD38 and CD123); these were selected based on clinical availability of novel targeted agents, approved or in development for other indications. Tissue array studies were performed and interpreted by a single hematopathologist (L.J) blinded to clinical data, using positive and negative controls, according to standard techniques. We also evaluated the clinical and epidemiological parameters, including different IP subtypes [ETP: CD1a-, sCD3- & CD8-, Pre/Pro-T: CD1a-, sCD3- & CD8+ or CD8- (11 marker T-ALL IP score was used to distinguish CD8- ETP vs. Pre/Pro-T), thymic: CD1a+ and mature: CD1a- & sCD3+] (Khogeer et al., Br J Haematol., 2019) & the presence of the unique MLLT10-PICALM fusion (n=6), as well as therapy and outcome. Comparisons of characteristics and outcomes of interest were made using a Wilcoxon rank sum test (continuous characteristics) or Fisher's exact test (categorical characteristics), unadjusted Cox proportional hazards regression models (overall survival), or unadjusted logistic regression models (complete remission after first line treatment). Results We identified the expression of novel targetable tissue proteins in all adult T-ALL/LBL cases [Table 1]. BCL2, CD38 & CD47 were expressed in majority of the cases, and CCR4 [Fig. 1] was expressed in 11/28 (39.3%) cases. CCR4 expression was significantly more common in the Pre/Pro-T (75%) vs. other IP subtypes (19%) (p=0.011); there was no other association of CCR4 expression with clinical characteristics/outcomes. We also observed differences in T-ALL vs. T-LBL, specifically T-ALL patients were more likely to be male (71% vs. LBL 38.9%, p=0.038). Surprisingly, T-LBL patients were more likely to have a family history of leukemia/lymphoma (41.2% vs. T-ALL 0%, p<0.001). In addition, a significantly different distribution of IP subtype in T-LBL was noted [Table 2]. Not surprisingly, T-LBL patients were more likely to receive 1st line Hyper-CVAD therapy (88.2% v. T-ALL 43.3%, p=0.005), & had a longer delay from diagnosis to initiation of therapy (median 14 vs. 4 days, p=0.012), however this did not appear to impact clinical outcome. In contrast, we observed an important association of IP subtype with outcome after therapy, including complete remission (p=0.035), & a trend suggesting differences in survival (p=0.069) [Table 3]. However, MLLT10-PICALM was not associated with any unique clinical features or with outcome (death, p=0.85; CR, p=0.98), although 4/6 patients underwent AlloHCT, suggesting an important role of AlloHCT in this subgroup. No other significant association of epidemiologic risk factors with phenotype or outcome was noted. Conclusion Using focused tissue array we have identified expression of tumor associated proteins in T-ALL/LBL including CCR4 (Pre/Pro-T IP) & others, which may be targets of therapeutic agents like mogamulizumab. Furthermore, our analysis demonstrates an important clinical impact of IP subtype in T-ALL/LBL, as well as important clinical & therapeutic differences in T-ALL vs. LBL. This study will help guide development of targeted clinical trials in T-ALL/LBL (CCR4 trial already in development). Further analyses are planned to determine the clinical & epidemiologic association of genetic lesions in this cohort. Disclosures Foran: Agios: Honoraria, Research Funding.

Background: Activation induced cytidine deaminase (AICDA or AID) causes somatic hypermutation (SHM) of the immunoglobulin heavy chain variable genes (IGHV). It has been widely hypothesized that aberrant targeting of AICDA creates additional driver mutations and intra-clonal heterogeneity which enables clonal evolution and thus disease progression. This hypothesis predicts that greater AICDA-mediated intraclonal heterogeneity will be associated with shortened progression free survival (PFS). To definitively test this hypothesis that AICDA-mediated heterogeneity is linked to risk of progression, we evaluated available samples from the largest US-based phase 3 trial of untreated follicular lymphoma patients treated with CHOP-based therapies, SWOG trial S0016. Methods: We have previously shown that ultradeep sequencing of two genes, the expressed IGHV and the 5' UTR of the translocated BCL2 allele, provide unrelated measures of AICDA-mediated genetic heterogeneity (Spence, J Immunol. 2014). Furthermore, the number of AICDA-mediated mutations in the 5' UTR of BCL2, but not in IGHV, correlates with the number of AICDA-mediated mutations at other known AICDA sites throughout the genome (such as PIM1, BCL6, RHOA, etc). Genomic DNA was prepared from all available paraffin-embedded specimens. Ultra-deep, amplicon-based sequencing (~10,000x) with internal controls to establish specimen-specific signal-to-noise parameters allowed sensitive and specific detection of sequence variants at 0.2% (FDR 1%). Results: For subjects with (152) and without (419) available specimens, the median duration of follow-up (11.3 years), the number of patients who progressed (60%), and other patient characteristics (demographics, histology, stage, FLIPI) were indistinguishable. Sequencing data that fulfilled strict quality metrics for low frequency variants were obtained for >75% of the specimens (114 for BCL2; 120 for IGHV); further analysis was restricted to these subjects. The extent of intraclonal variation within both the IGHV and the 5' UTR of BCL2 was highly variable. For BCL2, a median of 7 mutations/case were detected (range 0-61); the mutations were highly skewed to the RCYW motif (p<0.001), the preferred target of AICDA. These mutations defined a median of 5 subclones/case (range 1-22). The clonal IGHV was somatically mutated (<0.98 germline identity) in 94% of samples (median 0.89). For IGHV, a median of 113 subclones/case were detected (range 0-1531). Consistent with our prior study, no correlation was seen between the number of mutations detected in the IGHV and BCL2 or the number of subclones defined by IGHV and BCL2. Neither the number of mutations in nor the number of subclones defined by BCL2 or IGHV were prognostic. Cox regression showed no relationship between PFS and mutation number or subclone count based on either IGHV or BCL2 (hazard ratios are indistinguishable from 1; parameters were treated both as a continuous variables and dichotomized as quartiles). Furthermore, receiver operator curves did not suggest a cut point for any of these measures that would predict disease progression at any time (areas under the curve are indistinguishable from 0.5). Conclusions: Several measures of AICDA-mediated mutation and resulting subclonal heterogeneity were not found to be prognostic in previously untreated, advanced stage FL treated with CHOP-based regimens. In contrast, AICDA-mediated mutations have been reported to accrue during transformation from low grade FL to large cell lymphoma. This paradox calls for a more refined model to explain the role of AICDA in the progression of FL. Support: NIH/NCI grants U10CA180888, U10CA180819, U10CA180821, R21CA198072(WRB); and in part by GlaxoSmithKline. Disclosures Rimsza: NanoSting: Patents & Royalties: Named inventor on a patent licensed to NanoSting [Institution]. Leonard:Bayer Corporation: Consultancy; AstraZeneca: Consultancy; Genentech, Inc./F. Hoffmann-La Roche Ltd: Consultancy; Sandoz: Consultancy; ADC Therapeutics: Consultancy; Miltenyi: Consultancy; BeiGene: Consultancy; Sutro Biopharma: Consultancy; Celgene: Consultancy; Nordic Nanovector: Consultancy; Gilead: Consultancy; Karyopharm Therapeutics: Consultancy; Genentech, Inc./F. Hoffmann-La Roche Ltd: Consultancy; Bayer Corporation: Consultancy; Celgene: Consultancy; Epizyme, Inc: Consultancy; Merck: Consultancy; MorphoSys: Consultancy; AstraZeneca: Consultancy; Epizyme, Inc: Consultancy; Akcea Therapeutics: Consultancy; Miltenyi: Consultancy; ADC Therapeutics: Consultancy; BeiGene: Consultancy; Karyopharm Therapeutics: Consultancy; Merck: Consultancy; Sandoz: Consultancy; Gilead: Consultancy; Akcea Therapeutics: Consultancy; MorphoSys: Consultancy; Nordic Nanovector: Consultancy; Sutro Biopharma: Consultancy. Fisher:Celgene: Consultancy; Barclays: Honoraria; AstraZeneca: Consultancy; prIME: Honoraria. Smith:Portola Pharmaceuticals: Research Funding. Friedberg:Bayer: Honoraria, Other: Data & Safety Monitoring Committee; Acerta: Other: Data & Safety Monitoring Committee.

Background: Incidental pulmonary embolism (PE) is not infrequently found on CT scans with highest incidence reported in patients with cancer. It is unclear whether patients with symptomatic pulmonary embolism (iPE) have different clinical profile or outcomes compared to patients with symptomatic PE (sPE) and whether this is affected by the presence or type of malignancy. Objective: Compare baseline characteristics of patients diagnosed with iPE to patients with sPE with attention to cancer-specific risk factors as well as evaluate clinical outcomes. Methods: Consecutive patients enrolled in the Mayo Thrombophilia Clinic VTE Registry between March 1, 2013 and December 31st, 2018 with PE were followed prospectively. Outcomes of recurrent venous thromboembolism (VTE), major bleeding, clinically relevant non-major bleeding (CRNMB) and mortality data were collected every 3 months. Clinical outcomes were analyzed with specific focus on patients with cancer. Information was collected and managed using REDCap (Research Electronic Data Capture) and data analysis was performed using SAS software (SAS Institute Inc., Cary, North Carolina). Results: Out of a total of 1033 patients with PE in VTE registry, there were 655 patients with PE (284 with incidental and 363 symptomatic) who completed at least 3 months of anticoagulation and were started on treatment within 14 days of diagnosis. Apixaban was used in 220 (34 %), Rivaroxaban 175 (27 %), Enoxaparin 179 (27%), and Warfarin in 81 (12 %) patients. Overall cancer was present in 61% of patients and was more common in patients with iPE compared to sPE (80.2% vs 45.2%, p<0.001). Patients with iPE were less likely to have previous VTE (8.2% vs 25.5%, p< 0.0001) and tended to have lower BMI (mean 28.8 vs 31.4, p<0.0001) Characteristics of the subgroup of only cancer patients with PE are summarized in the Table. Of note, pancreatic and GI cancers were more common in patients with iPE. There were no differences in recurrent VTE, major bleeding and CRNMB in patients with iPE compared to sPE. This also held true for patients with underlying malignancies. Mortality rates were significantly higher in all patients with iPE even when adjusting for presence of malignancy (p=0.03). When adjusting for presence of metastatic malignancy though the difference was no longer present (p=0.33). Conclusion: Patients with iPE were more likely to have an underlying malignancy, potentially due to higher likelihood of undergoing staging imaging studies. Additionally, patients with iPE more often had metastatic disease which was associated with higher mortality. Recurrent VTE and bleeding outcomes were similar in patients with iPE and sPE, this was independent of the presence of underlying malignancy. Disclosures McBane: BMS: Research Funding.

Background: Chimeric antigen receptor T-cell (CAR-T) therapy has revolutionized the treatment of relapsed/refractory B-cell lymphoid malignancies. Axicabtagene ciloleucel (axi-cel), an anti-CD19 CAR-T not only targets the malignant B-cell, but can potentially also target and eliminate normal B-cells. This can interfere with the normal B-cell repertoire, compromising host humoral immunity such as decreased titers of common vaccines (DTaP, MMR). To assess if this was a clinically significant problem, we evaluated all recipients of axi-cel at our center between 6/2018 through 7/2019. Patients and methods: For patients who received commercial axi-cel, humoral immunity was evaluated both quantitatively [absolute lymphocyte count (ALC)] as well as qualitatively by serology titers [IgG antibodies (Abs)] for diphtheria, tetanus, pertussis, measles, mumps, and rubella, and total Immunoglobulin G (IgG) levels. Data was collected within 30 days prior to CAR-T infusion, then at day +30 and between days +60 and +100 after CAR-T infusion. Results: We identified 10 patients (males = 5, 50%), with a median age of 49.9 years (range 30-65) who received commercial axi-cel during the study period. Patient characteristics and indications for CAR-T therapy are shown in Table 1; the cohort represented a heavily pre-treated aggressive B-cell lymphoma patient population. Baseline information on antibody (Ab) titers was available in 8 patients. At baseline, all patients had positive tetanus IgG Abs (≥0.01 IU/mL), 7 had positive diphtheria IgG Abs (≥0.01 IU/mL), 6 had positive measles IgG Abs (≥ 1.1 AI), 5 had positive rubella IgG Abs (≥ 1.0 AI), 3 had positive mumps IgG Abs (≥ 1.1 AI). None of the patients had a positive pertussis IgG Abs (≥100 IU/mL). At follow-up, all patients with positive Ab at baseline maintained titers in the positive range at day +30 and between days +60 and +100 (Figure 1). None of the patients demonstrated a clinically meaningful decrease in Abs titers, despite a drop in ALC and IgG levels (table 2). Conclusions: Albeit a small sample size, IgG Ab titers for diphtheria, tetanus, measles, mumps, and rubella did not appear to be affected by axi-cel at a short interval follow-up after infusion (up to day +100). We plan to extend this analysis in a larger cohort with a longer-term prospective follow-up to validate our findings, especially in light of dropping absolute lymphocyte counts and IgG levels. Disclosures Ailawadhi: Celgene: Consultancy; Amgen: Consultancy, Research Funding; Cellectar: Research Funding; Janssen: Consultancy, Research Funding; Takeda: Consultancy; Pharmacyclics: Research Funding. Foran:Agios: Honoraria, Research Funding. Tun:Celgene: Research Funding; Curis: Research Funding; TG Therapeutics: Research Funding; Mundi-pharma: Research Funding; DTRM Biopharma: Research Funding; BMS: Research Funding. Chanan-Khan:Pharmacyclics: Research Funding; Merck: Research Funding; Jansen: Research Funding; Mayo Clinic: Employment; Ascentage: Research Funding; Millennium: Research Funding; AbbVie: Research Funding; Xencor: Research Funding. Kharfan-Dabaja:Daiichi Sankyo: Consultancy; Pharmacyclics: Consultancy.

Background: Immune thrombotic thrombocytopenic purpura (iTTP) is a potentially fatal hematologic disorder characterized by thrombocytopenia, microangiopathic hemolytic anemia, and ischemic organ impairment. The incidence of iTTP is higher among African-Americans (AA), however, differences in presentation and outcomes have not been fully investigated. In a multi-center cohort of patients with iTTP from the United States Thrombotic Microangiopathy (USTMA) Consortium, we tested the hypothesis that AA race is an independent predictor of poor outcomes including iTTP related mortality and relapse. Methods: We queried data from the USTMA iTTP registry, which currently includes data from 785 individual patients from 15 institutions across the United States. Data from at least one iTTP episode are available for 734 patients. The cohort is 35.1% (N = 272) White, 58.7% (N = 455) African American, 0.4% (N=3) Asian, 1.8% (N=14) Hispanic, and 4.0 % (N=31) other/unknown race. We restricted our analyses to AA and White participants because of small numbers in the other groups. We compared presenting features and treatments using the chi-squared test and t-test for categorical and continuous variables, respectively. A relapse was defined as a recurrent iTTP episode occurring at least 30 days after last therapeutic plasma exchange. To evaluate relapse-free survival, we included only patients enrolled in the registry at their first TTP episode (144 White and 246 AA) since patients presenting with a relapse as their index episode are already confirmed to have relapsing iTTP. Kaplan Meier analysis was used to compare relapse-free survival in White and AA patients, and a Cox regression model was developed to evaluate the independent effect of race on relapse, adjusting for potential confounders including age, sex, and the use of rituximab. Results: Demographics and presenting features of 390 individuals (144 White and 246 AA) presenting with a first episode of iTTP are shown in Table 1. Presenting symptoms including fever, confusion, seizure, memory deficits, stupor, headache, stroke, chest pain, abdominal pain, fatigue, and dark urine were similar between Whites and AA except for petechiae, which were more frequently documented in Whites (28.8% vs 17.7%, p=0.011). Presenting laboratory studies were also comparable though AA had a higher rate of elevated serum troponin (50.6% vs 32.5%, p=0.003), lower hemoglobin level (8.27 ± 0.13 vs 8.81 ± 0.19, p=0.0176) and platelet count (20.3 ± 1.2 vs 26.2 ± 3.2, p=0.0432). In addition to therapeutic plasma exchange and corticosteroids, rituximab was administered to 23.7% of White patients and 22.7% of AA during their first iTTP episode (P=0.815). Median time to platelet count recovery (days of daily plasma exchange until normal platelet count for two consecutive days) was shorter in AA compared with White patients [5 (IQR 4, 10) vs. 8 (IQR 5, 14), log rank P = 0.004]. AA race remained a significant predictor of the shorter time to platelet count recovery [HR 1.44 (95% CI 1.12, 1.85), P=0.004] after adjusting for rituximab therapy [HR 0.60 (95% CI 0.0.46, 0.80), P<0.001], female sex [HR 0.95 (95% CI 0.73, 1.22), P=0.669], age [HR 0.99 (95% CI 0.99, 1.01), P=0.682], platelet count [HR 1.00 (95% CI 0.99, 1.04), P=0.820] and LDH at presentation [HR 1.00 (95% CI 1.00, 1.00), P=0.525]. Death during the first episode occurred in 8.9% of White patients and 5.5% of AA patients (P=0.206). Relapse-free survival after the first episode of iTTP was lower in AA than White patients (Figure 1). AA race was associated with the reduced relapse free survival [HR 1.79 (95% CI 1.08, 2.98), P=0.024] in a Cox regression model adjusted for age [HR 1.00 (95% CI 0.98, 1.01), P=0.683], sex [HR 0.96 (95% CI 0.60, 1.54), P=0.867], and rituximab therapy [HR 0.93 (95% CI 0.55, 1.59), P=0.806]. Conclusion: African Americans with iTTP have a higher relapse rate and shorter relapse free survival after the first episode of the disease compared with Caucasian patients, which is independent of age, sex and rituximab therapy. Contrary to our hypothesis, acute outcomes of iTTP (time to platelet count recovery and mortality) were not worse in AA patients. The factors contributing to the higher relapse rate in AA with iTTP need to be further investigated. Our findings suggest that AA patients may also benefit from closer follow up. Disclosures Farland: Sanofi: Membership on an entity's Board of Directors or advisory committees. Metjian:Sanofi: Membership on an entity's Board of Directors or advisory committees. Raval:Bayer, Inc: Research Funding; Sanofi: Membership on an entity's Board of Directors or advisory committees. Liles:Shire: Other: PI on clinical trial Sickle cell ; Imara: Other: PI on Clinical trial- Sickle cell ; Novartis: Other: PI on clinical trial Sickle cell . Baumann Kreuziger:CSL Behring: Consultancy; Vaccine Injury Compensation Program: Consultancy. McCrae:Dova Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Pfizer Pharmaceutical: Membership on an entity's Board of Directors or advisory committees; Rigel Pharmaceutical: Membership on an entity's Board of Directors or advisory committees; Sanofi Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees. Zheng:Alexion: Speakers Bureau; Ablynx/Sanofi: Consultancy, Speakers Bureau; Clotsolution: Other: Co-Founder; Shire/Takeda: Research Funding. Cataland:Alexion: Consultancy, Research Funding; Ablynx/Sanofi: Consultancy, Research Funding. Chaturvedi:Shire/Takeda: Research Funding; Sanofi: Consultancy; Alexion: Consultancy.

AbstractMyeloproliferative Neoplasms (MPN) course can be complicated by thrombosis involving unusual sites as the splanchnic veins (SVT). Their management is challenging, given their composite vascular risk. We performed a retrospective, cohort study in the framework of the International Working Group for MPN Research and Treatment (IWG‐MRT), and AIRC‐Gruppo Italiano Malattie Mieloproliferative (AGIMM). A total of 518 MPN‐SVT cases were collected and compared with 1628 unselected, control MPN population, matched for disease subtype. Those with MPN‐SVT were younger (median 44 years) and enriched in females compared to controls; PV (37.1%) and ET (34.4%) were the most frequent diagnoses. JAK2V617F mutation was highly prevalent (90.2%), and 38.6% of cases had an additional hypercoagulable disorder. SVT recurrence rate was 1.6 per 100 patient‐years. Vitamin K‐antagonists (VKA) halved the incidence of recurrence (OR 0.48), unlike cytoreduction (OR 0.96), and were not associated with overall or gastrointestinal bleeding in multivariable analysis. Esophageal varices were the only independent predictor for major bleeding (OR 17.4). Among MPN‐SVT, risk of subsequent vascular events was skewed towards venous thromboses compared to controls. However, MPN‐SVT clinical course was overall benign: SVT were enriched in PMF with lower IPSS, resulting in significantly longer survival than controls; survival was not affected in PV and slightly reduced in ET. MPN‐U with SVT (n = 55) showed a particularly indolent phenotype, with no signs of disease evolution. In the to‐date largest, contemporary cohort of MPN‐SVT, VKA were confirmed effective in preventing recurrence, unlike cytoreduction, and safe; the major risk factor for bleeding was esophageal varices that therefore represent a major therapeutic target.

Abstract BACKGROUND NRG-CC001 sought to evaluate the neuro-protective effects of avoiding the peri-hippocampal stem cell niche using intensity-modulated radiotherapy during WBRT. METHODS Patients with brain metastasis were stratified by RPA class and prior radiosurgery/surgery and randomized to WBRT+M or HA-WBRT+ Memantine (M) (30Gy in 10 fractions). Standardized NCF tests and the M.D. Anderson Symptom Inventory Brain Tumor (MDASI-BT) were obtained at baseline, 2, 4, 6, and 12 months (mos). The primary endpoint was NCF failure defined using the reliable change index. Pre-specified secondary endpoints included patient-reported symptoms using the MDASI-BT. Time to NCF was reported as cumulative incidence (with death without NCF failure as a competing risk); between-arms differences were tested using Gray’s test. Deterioration at discrete time-points were tested using chi-square tests. MDASI-BT symptom burden, interference, and cognitive and neurologic burden were analyzed using mixed effects models and t-tests within the model using Hochberg’s multiplicity adjustment. RESULTS A total of 518 patients were randomized from 7/2016 to 3/2018. Median follow-up for alive patients was 12.1 mos, with no difference between arms in terms of toxicity, overall survival or intracranial progression-free survival. HA-WBRT+M was associated with lower risk of NCF failure (adjusted HR=0.739, 95% CI: 0.577–0.945, p=0.0.016), with differences first noted at 4 mos in Trail Making Test Part-B (23.3% vs. 40.4% deteriorated, p=0.012). Age did not dilute treatment effect. HA-WBRT+M was associated with reduced cognitive symptom burden in an imputed model (estimate=-0.29, p=0.0425), and also reduced overall symptom burden (p< 0.0001) and interference (p< 0.0016) at 6 mos. CONCLUSIONS The addition of HA to WBRT+M preserved NCF and reduced patient reported cognitive symptom burden, overall symptom burden and symptom interference and should be considered standard of care for any patient fit enough to have WBRT. Supported by grants UG1CA189867 (NCORP), U10CA180868 (NRG Oncology Operations), DCP from the National Cancer Institute.