Paulus, Aneel

Abstract INTRODUCTION: Significant burden of pain syndromes are reported in patients with hematological malignancies undergoing HSCT mostly due to underlying disease and associated treatments. Opioid analgesics and benzodiazepines are routinely used for symptomatic management in this patient population. The use of narcotic analgesics and benzodiazepines in non-transplant hospitalized patients has been shown to adversely affect health related outcomes such as length-of-stay (LOS), falls and other complications. However, there is a significant knowledge gap regarding the patterns of opioid and benzodiazepine use and their impact on health outcomes in HSCT patients. METHODS: We identified 275 patients from the year 2015-2018 who underwent HSCT (allogeneic and autologous transplants) at our center for a variety of hematological malignancies. Opioid exposure was defined in three groups of patients 1) Opioid naïve: those did not report prior use of opioid at admission and who were not prescribed opioid during hospitalization, 2) Previous Opioid users: those who reported active use of opioid at admission and continued during hospitalization 3) New Opioid users: Patients who did not report opioid use at admission but were prescribed opioid during hospitalization. Multivariable analysis was performed to identify differences in opioid status, opioid use, benzodiazepine use, disease diagnosis, Karnofsky score, gender, age, race, and marital status with associated complications (Poisson regression), emergency department visits (Logistic Regression) and length of stay (Ordinal Logistic Regression) Figure 1 and Figure 2. RESULTS: The median age of patients was 59 (range: 25-74 ) years with slight male predominance (57%). Patients undergoing autologous transplants for multiple myeloma (MM) comprised 48% of the population. The majority (72 %) were exposed to opioid during hospitalization. Ninety two percent of the opioid naïve population (28% of the total population) underwent autologous transplant. Conversely, 36% of patients undergoing autologous transplants never received opiates during hospitalization as compared to 7% of those who received an allogeneic transplant. Median morphine milligram equivalent daily dose was 3.1 mg. Median diazepam equivalent daily dosage in patients that were opiate exposed was 2.07 milligram. Of the total transplant population, 55% received benzodiazepine concurrently with opiates during hospitalization. 76 % of the population was exposed to both opioid and benzodiazepine. Twenty five percent of those who were exposed to opioid did not receive benzodiazepines. Sixty four percent of the MM patients were exposed to opioid of which majority (59%) were previous opioid users. Of the non-MM patients undergoing HSCT, 80% were exposed to opioid of which 36% were previous opioid users and 64% were new users. A wide range of complications from neutropenic fever to death, were seen in 89% of all patients (opioid users and non-users) but all the falls occurred in patients who were on opioid medications. Autologous transplant recipients had higher odds of having a greater number of complications compared to Allogeneic transplant patients (OR 1.25, 95% CI: 1.01 - 1.55, p=0.04), as well as a reduced odds of having a medium or high length of stay (OR 0.03, 95% CI: 0.02 - 0.07). Of the opioid naïve patients, 6% presented to the ED within 30 days of discharge versus 15% of those that were exposed to opiates during hospitalization. Benzodiazepine use at admission for HSCT was associated with greater odd of presenting to ED within 30 days of discharge (OR 3.94, 95% CI: 1.55-10.04) and this was more significant in patients with MM (OR 4.08, 95% CI: 1.01-16.44). Finally, we also saw a trend towards longer stay in patients who were exposed to opioids as compared to opioid naïve (40% vs. 17%). CONCLUSION: Our study, albeit limited due to its retrospective design, is among the first to report the patterns of use and the impact of opioids and benzodiazepines in patients undergoing HSCT. Our results indicate that the use of these medications is frequent in this population and as in the non-transplant hospitalized patients and is associated with more emergency room visits post discharge, along with other potentially adverse outcomes. Disclosures Kharfan-Dabaja: Incyte Corp: Speakers Bureau; Seattle Genetics: Speakers Bureau; Alexion Pharmaceuticals: Speakers Bureau. Ailawadhi:Amgen: Consultancy; Pharmacyclics: Research Funding; Celgene: Consultancy; Takeda: Consultancy; Janssen: Consultancy.

Abstract INTRODUCTION: Treatment of chronic lymphocytic leukemia (CLL) has expanded significantly with the approval of multiple small molecule inhibitors. This is of great significance for patients with adverse cytogenetic features who tend to respond poorly to standard chemo-immunotherapy (CIT). While single agent ibrutinib and venetoclax (V) have shown high rates of overall response, complete remission and minimal residual disease (MRD) eradication rates remain low. This argues for further testing and development of various combination strategies. The MURANO trial compared venetoclax and rituximab (VR) versus bendamustine and rituximab (BR) in patients with relapsed/refractory CLL reporting clear superiority of VR over BR. MRD rates in the bone marrow were reported to be 27.3% for VR versus 1.5% for BR. Given much higher rates of MRD eradication with combination of small molecule inhibitors and monoclonal antibodies (mAb) compared to standard CIT, we performed a comparative investigation into the direct and immune-mediated cytolytic effects of VR versus V + Obinutuzumab (O, type II anti-CD20 mAb) in primary CLL cells and B-lymphoid cell lines. METHODS: CD19+ B-cells were isolated from PBMCs of CLL patients (N=3). For all experiments using primary CLL cells, concentration of VR and VO was 3nM (V) and 10ug /ml (R, O), respectively. For cell lines, VR and VO was used at 5uM (V) and 10ug /ml (R, O), respectively. Apoptosis was determined by annexin-V/PI staining followed by flow cytometry. Antibody-dependent cell-mediated cytotoxicity (ADCC) induced by VR and VO was assessed in Calcein AM labeled CLL cells or cell lines co-cultured with healthy donor PBMCs (E:T ratio, 40:1); complement-dependent cytotoxicity (CDC) was measured using 10% serum from a healthy human donor. RESULTS: We assessed the ability of V+/-O or V+/-R to induce apoptotic cell death in the CD20+ BCWM.1 cell line (Waldenström's macroglobulinemia [WM] phenotype) and the MEC-1 cell line (B-PLL phenotype); with CD20- RPCI-WM1 (WM cells, negative control). Notably, Bcl-2 protein is expressed in all the aforementioned cell lines. We observed that single agent V, O and R induced ~30%, 61% and 13.64% annexin V/PI positivity in BCWM.1 cells, respectively. However, a significant degree of cell death was noted in VO-treated cells (~74%) compared to VR-treated cells (~40%) (p<0.01). Next, we examined for apoptosis in MEC1 cells and noted a similar trend; where the VO combination induced markedly more cell death (~71%) than VR (~57%). Contrastingly, in RPCI-WM1 cells neither single agent O or R could elicit >12% annexin V/PI positivity and where the addition of V increased apoptosis by only 3 - 4%. We also examined the apoptotic potential of VO or VR in tumor cells from low, intermediate and high-risk CLL patients. In low and intermediate-risk CLL cells from low and intermediate-risk patients, V alone induced ~30% cell death, which increased significantly with the addition of O (VO) to between 48 - 52%. Contrastingly, the combination of VR did not induce more than 29 - 32% apoptosis. In CLL cells from high-risk patient, we noted that exposure to single agent V induced ~ 28% cell death and in VO-treated cells, this number increased to 47%. We also examined for ADCC and CDC in the same cell lines and primary CLL cells. Despite considerable variability, single agent O and VO treatment of tumor cells resulted in greater ADCC than VR treatment. By contrast, in single agent R or VR-treated cells, more CDC was observed. CONCLUSION: Our preliminary investigation in VR- and VO-treated cell lines and primary CLL cells suggests the VO combination may be superior to VR in induction of direct tumor cell death. Mechanistic experiments underway will provide further insight and can aid in design of future VO-based clinical studies in CLL. Disclosures Ailawadhi: Pharmacyclics: Research Funding; Takeda: Consultancy; Celgene: Consultancy; Janssen: Consultancy; Amgen: Consultancy.

Abstract Background: Racial disparities in outcomes of cancer patients have been reported. Access to comprehensive cancer centers is associated with improved overall survival (OS) but racial/ethnic minorities may have a disparate access to such care. While the impact of treatment facility volume on outcomes has been evaluated, outcomes of centers with minority-predominant patient population have not been studied. We compared demographic profiles, facility level data and OS of patients treated at minority-predominant facilities to facilities that treated predominantly non-Hispanic Whites (NHW) with non-DLBCL. Methods: The National Cancer Database (NCDB) was used to identify all non-DLBCL patients diagnosed between 2004 and 2015. "Minority-treating facilities" were defined as facilities in the top decile by proportion for initial treatment of non-Hispanic African-Americans (NHAA), Hispanics and other races. We performed univariate and multivariate analyses to compare sociodemographic and clinical factors influencing outcomes between minority treating and non-minority treating facilities. A subgroup analysis stratified by race/ethnicity was also conducted to study the effect of treating facilities on the outcome of NHWs and minorities separately. Results: Of 1339 total facilities, 123 (9.1%) qualified as minority treating. Of 207,239 eligible patients in NCDB, 18,719 (9.03%) received treatment at the minority-treating facilities and of these, 11,190 (~60%) belonged to the minority races. Overall, 4.5% (6,988/156,664) NHWs and 30% (11,190/37,639) minorities received treatment at the minority-treating facilities. Several demographic and facility level characteristics were significantly different among the patients treated at minority-treating facilities as compared to non-minority treating facilities. Overall, significantly higher number of patients in minority-treating hospitals had lower income and education, had Medicaid coverage or lack of insurance. The OS of patients in minority treating facilities was significantly worse as compared to non-minority facilities (Figures). On multivariate analysis, patients who received treatment at minority-treating facilities were at 10% (HR=1.10, 95% CI: 1.06-1.14 p<0.001) higher risk of mortality as compared to those treated at the non-minority treating facilities. On multivariate analysis, NHAA (30% increased risk) and 'other races' (9% increased risk) were at significantly higher risk of mortality as compared to the NHW (Table 2). To study the effect of treatment at minority-treating facilities on OS among the patients of same race/ethnicity group, a multivariate analysis was also run separately for NHW and racial minorities. The NHWs who received treatment at minority-treating facilities were at 13% higher risk of death (HR=1.13, 95% CI: 1.08-1.19 p<0.001) as compared to NHWs who were treated at non-minority treating facilities. Similarly, the racial minorities who received treatment at minority treating facilities were at 8% higher risk of death (HR=1.08, 95% CI: 1.03-1.19 p=0.003) as compared to those who received treatment at the nonminority treating facilities. Conclusions:Outcomes of patients who received treatment at minority treating facilities was significantly worse than those at non-minority treating facilities. This was true for NHWs and racial minorities separately as well. Several demographic and facility level characteristics were significantly different in the two groups however OS remained worse after adjusting for them. Causes of poor outcomes at minority-treating facilities must be analyzed to mitigate them and improve outcomes for all. Figure. Figure. Disclosures Ailawadhi: Takeda: Consultancy; Celgene: Consultancy; Amgen: Consultancy; Janssen: Consultancy; Pharmacyclics: Research Funding.

Abstract Introduction Recent advances in the understanding of the WM pathobiology led to the expansion of our therapeutic options in this disease. A number of targeted drugs are either available or under investigation and are poised to change the chemo-immunotherapy paradigm in the treatment of WM. Now more than ever, an individualized treatment approach for patients with WM is possible, where patient characteristics and preferences can be matched by different treatment goals and side effect profiles. While deep responses have been associated with longer disease-free survival in other hematologic malignancies, data on patients with WM are sparse. We report the impact of depth of response in disease-free and overall survival (OS) in WM. Methods WM patients consecutively seen at Mayo Clinic between 01/1998 and 12/2016 were reviewed for response to therapy and disease burden. The best response achieved after the treatment of interest (TOI) was classified using the IWWM-7 Response Criteria. The included TOI were: BR, DRC, BDR and high-dose chemotherapy followed by ASCT. All time-to-event analyses were performed from the TOI initiation date using the Kaplan-Meier method and the log-rank test. A landmark analysis from the date-of-best response was also performed for OS to prevent immortal-time bias. Univariate and multivariate analyses of progression-free survival (PFS) and time-to-next therapy (TTNT) were performed using the Cox regression method. Results A total of 181 patients had disease response assessed after the TOI. Baseline characteristics at time of diagnosis are summarized in table 1. The median follow up from TOI was 3.8 years (95% CI: 3-4), the majority of patients received TOI as salvage therapy [n=112 (63%); median 2nd line (rage 1-11)]. Best response rates with the corresponding 5-year PFS and TTNT are summarized in table 2. The median OS from TOI was longer in patients who achieved at least a PR [median 7.2 years (95% CI: 5-NR) vs 3.7 years (95% CI: 1.6-NR), p=0.01]. A trend towards a longer OS was also seen with deeper responses (PR or better) achieved with frontline therapy [median 5.8 years (95% CI: 5.8-NR) vs 3.4 years (95% CI: 1.6-NR), p=0.24]. Figure 1 shows the correlation between deeper responses with PFS and TTNT. Among patients achieving a PR or VGPR, those with a normal FLC ratio post TOI demonstrated a longer PFS and TTNT [PFS: median NR (95% CI: 3.4-NR) vs 4.9 years (95% CI: 2.8-8.7), p=0.01; TTNT: median NR (95% CI: 3.5-NR) vs 5.2 years (95% CI: 4.2-9.4), p=0.04], figure 2. In a multivariate analysis including normal FLC ratio, normal IgM level and minimal BM involvement (<5%) post TOI, normal FLC ratio remained an independent prognostic factor for longer PFS and TTNT. Similar trends were seen when considering treatment naïve and relapsed/refractory patients independently (data not shown). Discussion Our results not only suggest an association between depth of response with PFS and TTNT, but also with OS in patients with WM. A normal FLC ratio (not part of the IWWM-7 response criteria) seems to predict a longer disease-free interval in patients achieving a PR or VGPR. Disclosures Gertz: Ionis: Honoraria; Apellis: Consultancy; annexon: Consultancy; Prothena: Honoraria; janssen: Consultancy; Physicians Education Resource: Consultancy; Alnylam: Honoraria; Teva: Consultancy; spectrum: Consultancy, Honoraria; Medscape: Consultancy; celgene: Consultancy; Research to Practice: Consultancy; Amgen: Consultancy; Abbvie: Consultancy. Kapoor:Takeda: Research Funding; Celgene: Research Funding. Ailawadhi:Amgen: Consultancy; Janssen: Consultancy; Takeda: Consultancy; Pharmacyclics: Research Funding; Celgene: Consultancy. Reeder:Affimed: Research Funding. Witzig:Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Dispenzieri:Celgene, Takeda, Prothena, Jannsen, Pfizer, Alnylam, GSK: Research Funding. Lacy:Celgene: Research Funding. Kumar:Janssen: 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, Research Funding; KITE: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding. Ansell:Seattle Genetics: Research Funding; Celldex: Research Funding; Bristol-Myers Squibb: Research Funding; LAM Therapeutics: Research Funding; Trillium: Research Funding; Pfizer: Research Funding; Takeda: Research Funding; Merck & Co: Research Funding; Affimed: Research Funding; Regeneron: Research Funding.

Abstract Introduction Immunoglobulin M monoclonal gammopathy of undetermined significance (IgM MGUS) is a relatively common pre-malignant condition that may progress to Waldenstrom macroglobulinemia (WM), an incurable low-grade non-Hodgkin lymphoma. The acquisition of genomic alterations in a multistep process of progression is likely a central mechanism responsible for the progression of IgM MGUS to WM, leading to increased tumor burden and end-organ damage. The exact role of the immune system in this process is still poorly characterized. The modulation of the immune system by malignant cells leading to anti-lymphoma immunity or immune evasion is a well-stablished principle associated with lymphoma survival and progression, respectively. The understanding of the pathobiology of IgM MGUS and WM has grown significantly over the last few years; however, most of the past research has focused on genetics and flow cytometric analysis of malignant cells. The introduction of CyTOF, a novel platform coupling mass spectometry with single-cell flow cytometry using antibody-metal isotope pairs, has allowed a broader single-cell analysis and the study of functional profiles. We here report the use of CyTOF technology to comprehensively profile the immune system of patients with IgM MGUS and WM. Methods Viably-cryopreserved (DMSO 10%) single-cell suspensions containing peripheral blood mononuclear cells from 15 patients (WM n=9 and IgM MGUS n=6) were used in this study. Recovered cells (1-3 x 106 per sample) were stained with a 30-parameter surface protein CyTOF panel designed to characterize multiple cell types and profile the immune system. Nucleated cellular events were identified using a DNA intercalator conjugated to natural abundance iridium (191Ir and 193Ir). Cisplatin (195Pt) was used for dead-live cell discrimination and calibration beads containing natural abundance cerium (140/142Ce), europium (151/153Eu), holmium (165Ho), and lutetium (175/176Lu) were used for normalization of the instrument signal. CyTOF analysis of normalized files was carried out using the Astrolabe Diagnostics platform. Cell clusters were assigned using the FlowSOM package and differential abundance analysis was performed using the edgeR package. Analysis is adjusted for multiple comparisons. Results The median live single-cell count for the entire cohort was 573,300 (range 50,681 to 869,727), representing a median of 81% (range 39% to 87%) of the total event counts [median 820,800 (range 130,452 to 1,000,000]. The cell count and the proportion of event count was similar in patients with WM or IgM MGUS. T cells represented 45.8% of the total events; granulocytes represented 31.3%; NK cells represented 8.6%; monocytes represented 8.1%; B cells represented 2.4% of the total events for the entire cohort. Figure 1 shows a heat map of different immune cell sub-types proportion per patient sample. A difference was noted in the proportion of monocytes (CD14+, CD16+) and B-cells when comparing patients with IgM MGUS and WM (figure 2). Patients with WM had a higher proportion of monocytes compared to IgM MGUS patients (p=0.05). A higher proportion of B-cells was noted in patients with IgM MGUS when compared to WM (4.2% vs 0.6%, p=0.01). When B-cells were sub-classified as naïve, transitional, non-switched memory, switched memory, and plasmablasts, the proportion of non-switched memory B-cells was higher in IgM MGUS compared to WM (p=0.05). While the results of this pilot study suggest important differences between IgM MGUS and WM as regards the immune repertoire, confirmatory studies are in progress in a larger cohort of patients. Conclusion To our knowledge, this is the first study of mass cytometry in patients with WM and IgM MGUS patients. A higher proportion of monocytes and lower proportion of memory B-cells was noted in patients with WM compared to IgM MGUS. CyTOF study of the immune profile in these patients is feasible and can potentially uncover relationships between cell types not typically associated with the disease progression continuum (IgM MGUS to WM). While definitive conclusion cannot be made using this dataset due to the small sample size, CyTOF is a powerful tool in the study of the immune profile of WM patients. Disclosures Gertz: Amgen: Consultancy; Abbvie: Consultancy; Apellis: Consultancy; annexon: Consultancy; spectrum: Consultancy, Honoraria; Teva: Consultancy; Alnylam: Honoraria; Physicians Education Resource: Consultancy; Ionis: Honoraria; janssen: Consultancy; celgene: Consultancy; Prothena: Honoraria; Research to Practice: Consultancy; Medscape: Consultancy. Kapoor:Celgene: Research Funding; Takeda: Research Funding. Ailawadhi:Takeda: Consultancy; Amgen: Consultancy; Janssen: Consultancy; Celgene: Consultancy; Pharmacyclics: Research Funding. Reeder:Affimed: Research Funding. Ansell:Seattle Genetics: Research Funding; Regeneron: Research Funding; Takeda: Research Funding; Pfizer: Research Funding; Merck & Co: Research Funding; Trillium: Research Funding; Affimed: Research Funding; LAM Therapeutics: Research Funding; Celldex: Research Funding; Bristol-Myers Squibb: Research Funding.

Abstract Background: The treatment of NHL has witnessed a paradigm shift over time, with targeted immunotherapy, stem cell transplant (SCT) among others. Historically, XRT was used quite frequently for the management of NHL but with advent of better systemic therapy, its utilization has changed. Trends and patterns of care for XRT use have never been formally reported. Methods: We identified patients with NHL diagnosis in the National Cancer Database (NCDB) between years 2004 and 2015. Demographic, clinical, facility level, initial treatment and outcome data were collected. The utilization of XRT in diffuse large B-cell (DLBCL) and non-DLBCL NHL were analyzed separately by univariate and multivariate analyses. To analyze the trends in the rates of XRT, we applied segmented linear regression to calculate the average annual percent change (AAPC) and 95% confidence Interval (CI) with a 'p' value. AAPC and CIs were calculated using the segmented package in R studio v1.1.49. Rest of the analyses was conducted using StataCorp version 15.1. Results: A total of 133,182 DLBCL and 204,933 non-DLBCL patients were identified. Among patients with DLBCL, 27,895 (20.9%) patients received RT. The rate of XRT declined from 25% in 2004 to 18.4% in 2015 with estimated AAPC of -0.59% (95%CI: -0.70- -0.49), p= 0.03 (Figure 1). In a subgroup analysis, a similar decline in the rate of XRT was evident across all the age groups, combined stages I and II vs stages III and IV and nodal vs extra nodal DLBCL (Table 1). Among non DLBCL, 33,369 (16.3%) patients received XRT. There was a statistically significant decline in the rate of XRT from 18.03% in 2004 to 16.3% in 2014 with an AAPC of -0.26 (95%CI: -0.38- -0.14) p <0.001 (Figure 1). On the subgroup analysis, the utilization of XRT declined across all the studied subgroups except among patients aged 80 years and above (Table 1). On multivariate analysis, several demographic, clinical and facility level factors were found to be significantly associated with XRT utilization in NHL (Table 2). In particular, older age groups, racial/ethnic minorities, advanced stages, higher Charlson comorbidity scores and diagnosis in the more recent calendar years were associated with lesser chances of receiving RT. Extranodal DLBCL had lower utilization while extranodal non-DLBCL had increased XRT utilization. Conclusion: There has been a significant decline in the utilization of XRT among patients with NHL (DLBCL and non-DLBCL) in the US since 2004, likely due to introduction of practice changing systemic therapeutics. There is still significant heterogeneity noted in practice patterns regarding utilization of XRT across the US. Having more standardized guidelines will help streamline delivery of evidence-based patient care. Disclosures Ailawadhi: Celgene: Consultancy; Janssen: Consultancy; Amgen: Consultancy; Takeda: Consultancy; Pharmacyclics: Research Funding.

Background The ubiquitin proteasome system (UPS) maintains homeostasis in eukaryotic cells by degrading and recycling proteins associated with DNA transcription and cell cycle regulation. In tumor cells with a high protein turnover rate, particularly in immunoglobulin secreting cancers such as Waldenströms Macroglobulinemia (WM), proteasomes are critical for sustained cell proliferation. Proteasome inhibitors (PI) such as bortezomib and carfilzomib target the B5 subunit of the proteasome catalytic core and disrupt its activity leading to accumulation of polyubiquitinated proteins. Although highly effective in WM, persistent use of bortezomib eventually leads to emergence of a bortezomib resistant (BR) subclone. Point mutation in the PSMB5 gene (encoding the B5 subunit) leading to altered binding kinetics is identified as a potential underlying mechanism of PI resistance. Despite these adaptive modifications that support resistance to PI resistance, the UPS as a whole remains a relevant target with vulnerable sites that can be therapeutically exploited. The 19S cap of the proteasome contains deubiquitinating enzymes (DUBS) that function to deubiquitinate proteins prior to their entry into the proteasomal core. Using a novel DUB-inhibitor b-AP15, which blocks the UCHL5 and USP14 DUBS, D’Arcy et al demonstrated that disruption of these DUBS does not alter proteasomal activity yet induces robust tumor cell death in various cancers. Aim Investigation of b-AP15 in preclinical models of BR WM and characterization of associated downstream signaling interactions. Methods For these studies, we developed and used BR variants of the most commonly used WM cell lines (variants termed BCWM.1/BR, RPCI-WM1/BR and MWCL-1/BR). Proteasomal activity was measured in these cells using synthetic fluorogenic peptide substrates and apoptosis was measured by annexin-v/PI staining. For gene expression profiling (GEP), the Nanostring nCounter mRNA quantification assay was utilized. Results We treated all BR WM clones with either single agent bortezomib (10nM), carfilzomib (10nM), b-AP15 (100nM) or all three agents in combination and assessed their effect on chymotrypsin-like, caspase-like and trypsin-like proteasomal activity. b-AP15, either alone or in combination with the other PI, did not alter proteasomal activity, nor did it abrogate the inhibition of chymotrypsin-like activity of other PI. Although proteasomal activity was not disrupted, we observed an increase in high molecular weight ubiquitinated proteins on immunoblot analysis. We hypothesized that despite the BR cells resistance to B5-targeting PI, they would remain sensitive to UPS inhibition if targeted through DUB inhibition. We treated BR cells with b-AP15 at concentrations ranging from 50nM - 1.25uM and observed that b-AP15 induced robust WM cell death in a dose and time dependent manner. Apoptosis was more pronounced in MWCL-1/BR cells and optimal cell death (55%) was observed at 500nM; however a commitment towards cellular demise was evident by PARP-1 and caspase cleavage as early as 3 hrs. Use of a pan-caspase inhibitor resulted in rescuing of the BR WM cells from b-AP15 mediated death and demonstrated a caspase-dependent death process. In order to gain further mechanistic insight into the processes that regulates response to b-AP15, we performed GEP and immunoblot of BR WM cells treated with 50nM of b-AP15. We observed an increase in phospho-p38 protein, which belongs to the MAPK family and regulates IL8 secretion. When BR WM cells were treated with a p38 inhibitor in combination with b-AP15, a significant decrease in cell viability was noted relative to b-AP15 (100nM) alone. Furthermore, GEP and network analysis identified key regulator genes associated with p53, cell cycle and MAPK signaling. Summary We provide first evidence that inhibition of the DUBS, UCHL5 and USP14 with b-AP15 results in caspase-dependent apoptosis of BR WM cells. Our investigation uncovers important molecular interactions that may dictate the BR cells responsiveness to DUB-inhibition by b-AP15. These observations validate the pervasive role of the UPS and confirm alternate therapeutics targets using our unique BR WM models. We are grateful to the Waterfall Waldenström Macroglobulinemia Research Fund, the Leukemia and Lymphoma Society and the International Waldenström Macroglobulinemia Foundation for their continued support. Disclosures: Martin: Teva: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Genentech: Speakers Bureau; Millennium: Research Funding; Seattle Genetics: Consultancy, Speakers Bureau.

Abstract Background: CLL is the most common leukemia diagnosis in adults and its treatment has undergone significant change from chemotherapy, to immunotherapy and now targeted kinase inhibitors, leading to improved overall survival (OS). With improving survivorship, SPMs can occur but an in-depth analysis of risks and trends of SPMs in CLL survivors is lacking. We performed a population-based analysis to evaluate this. Methods: Patients in the Surveillance, Epidemiology and End Results (SEER) database diagnosed with CLL between 1973-2015 were included. Due to variation in management techniques over time, the cohort was divided in four time periods: 1973-1982, 1983-1992, 1993-2002 and 2003-2015. We evaluated differences in risk for SPMs among CLL survivors compared to risk of individual malignancies expected in the general population during these time periods and studied the effect of demographics and time since CLL diagnosis. Results: Over a nearly 270,000 person-year follow up, 6,467 new SPMs were diagnosed with a standardized incidence ratio (SIR) of 1.2 (95% CI 1.17-1.23), which resulted in a 39 excess cancers per 10,000 population. The CLL survivors had a 20% overall increased risk of developing SPMs (excluding non-squamous skin cancer) compared to the general population. The risks for both solid (SIR 1.15 CI 95% 1.12-1.18) and hematological malignancies (SIR 1.61 95% CI 1.5-1.73) was higher than the expected in the general population. However, the risk for individual cancers was heterogeneous. The tumors associated with the highest risk were Hodgkin lymphoma (almost 8 times higher), Kaposi Sarcoma (4 times), non-epithelial skin cancers (4 times), salivary gland cancer (3 times) and acute lymphocytic leukemia (3 times). In contrast, tumors in the hepatobiliary system, female breast and female genital system were associated with a lower risk than the general population. The highest SIR across the study periods was observed in the younger population (ages 15-49). Although the risk increased in all ethnicities, it was statistically significant only in Caucasians. There was no gender-wise difference in SIR during any of the four time periods. A statistically significant increase in SIR was observed for both men and women from 1973-1982 to 2003-2015. This was mostly due to an increase in risk of hematological malignancies from 1.08 early in the study to 2.56 in the most recent study period. The SIR in solid tumors did not change significantly over time; in absolute terms, however, lung carcinoma contributed the most to the excess risk, followed by non-epithelial skin cancers and non-Hodgkin's lymphoma. The risk of developing a SPM was higher for the CLL survivors during most of the latency periods, but it was statistically significant during the 2-5 months and 12-59 months after diagnosis. A multivariate analysis was conducted to evaluate the impact of period of diagnosis on the development of SPMs among these patients. After adjusting for gender, ethnicity, radiation therapy, chemotherapy, and age at diagnosis of CLL, patients diagnosed with CLL in the most recent time period were at 45% higher risk of developing SPMs as compared to the patient diagnosed during 1973-1982 (Hazard ratio(HR) =1.45 95%CI:1.34-1.6, p<0.001). Moreover increased HRs were also observed for 1983-1992 and 1993-2002 time periods (Fig. 1) Conclusions: With improving therapeutics for cancer treatment, survivorship is improving as well and the risk of SPMs needs to be better understood and addressed. This is truer for CLL, where majority of patients have a favorable survival. The risk of SPMs was 20% higher in CLL survivors than in the general population and was most prominent in the survivors aged 15-49 years at the time of CLL diagnosis. The risk of individual malignancies may be heterogenous but there has been an increase in risk of SPMs over time, mainly due to an increase of secondary hematological malignancies in recent years. Active survivorship plans and long-term surveillance for SPMs is crucial for improved outcomes of patients with a history of CLL. Disclosures Ailawadhi: Janssen: Consultancy; Celgene: Consultancy; Amgen: Consultancy; Takeda: Consultancy; Pharmacyclics: Research Funding.

Abstract Background Waldenstršms macroglobulinemia (WM) is a rare and incurable indolent Non-Hodgkin's lymphoplasmacytic lymphoma. Rarity and limited availability of authentic preclinical models has been a major constraint in drug development for WM. We recently reported the establishment and characterization of a novel human WM cell line, RPCI-WM1. Thereafter we evaluated the tumorigenic potential of this unique WM cell line in a xenograft mouse model along with its ability to produce human IgM in vivo. Moreover, we assessed its potential as a possible model for enhanced understanding of WM cell biology in vivo and a mechanism to conduct functional studies and preclinical anti-WM drug evaluation. Aim The primary goal of this experiment was to develop and validate an in vivo WM model that can be used to investigate WM cell biology as well as drug evaluation. Methods The RPCI-WM1 cell line (1x106 cells) was injected both subcutaneously and via tail vein into female SCID mice. Engraftment was validated via detection of human IgM (ELISA) and tumor growth (as well as response to therapy) was monitored by weekly assessment of IgM levels and external tumor formation measurements. Results After subcutaneous injection (flank) into mice, the RPCI-WM1 cells developed localized tumors that secreted human IgM detectable in serum as early as 14 days. Progressive increase in IgM was measured in the serum and this corresponded with tumor growth in a time-dependent fashion. On average, tumor tissues grew to a median of 3 cm and IgM levels reached a median of 823 ng/mL by Day 30 post-implantation. We also assessed the practical utility of this xenograft mouse model for evaluation of therapeutics, using a compound X (propriety drug with demonstrable in vitro anti-WM effects). Eleven days post-implantation, the mice were randomized into 3 groups receiving either DMSO (n=6), 100 mg of compound X (n=7) or 200 mg/kg of compound X (n=7) every alternate day via intraperitoneal injection for 26 days. On Day 37, mice were sacrificed and tumor volume was measured. We observed a 48% reduction in tumor volume in the 100mg/kg cohort, with no additional anti-WM benefit noted in the 200mg/kg cohort. Human IgM secreted by the xenografted tumors was measured by ELISA and was significantly lower in mice treated with compound X versus the control group (Figure 1). We also conducted immunohistochemistry (IHC) analysis on tumor tissues obtained from 9 mice treated with compound X (both dose cohorts) or DMSO alone. IHC staining demonstrated changes in the known target proteins of compound X (such as BCL2, p53, Ki-67) between the treated and untreated mice. Summary Thus we demonstrate that the RPCI-WM1 cell line can be dependably used to induce tumor growth through xenotransplantation in SCID mice and this mimics the IgM secreting clinical disease model. This can then be used to serve as a platform for preclinical testing of novel anti-WM therapeutics and allow for subsequent correlative studies for pharmacodynamics purpose. Comprehensive data regarding this model its utility in evaluation of various biological questions such as those relevant to the tumor microenvironment as well therapeutic modeling will be presented. We are grateful to the Leukemia and Lymphoma Society and the International Waldenstršm Macroglobulinemia Foundation for their continued support. Disclosures: No relevant conflicts of interest to declare.

Abstract Background: Clinical trials are fundamental to advance therapeutics systematically and improve patient outcomes. Despite this, enrollment on clinical trials remains dismal in the United States (US) and is a constant focus of healthcare policy. We studied distribution of clinical trials for B-cell malignancies over time across the US and unique clinical trial opportunities i.e. individual clinical trials for the given diagnosis at a site that patients may have access to participate. Methods: We abstracted data from clinicaltrials.gov for all trials that had non-Hodgkin lymphoma (NHL) or multiple myeloma (MM) as an inclusion indication between 1999-2018. Clinical trial characteristics and distribution over US geographical divisions (West, Midwest, Northeast, and South) were studied, and differences were assessed by Chi-square test. Results: A total of 1930 trials were identified (NHL: 982, MM: 948), of which 483 were recruiting at the time of data abstraction (NHL: 250, MM: 233). Over the past 2 decades, 182691 patients were enrolled on the various trials (NHL: 81592, MM: 101099). Trials by phase of study included phase 1: 629, phase 1/2: 316, phase 2: 813, phase 2/3: 11 and phase 3: 161. Number of trials by phase separated by NHL and MM are shown in Figure 1. Of these, 197 trials were randomized (NHL: 67, MM: 130). Geographical distribution of trials by diagnosis type is shown in Figure 2. A total of 31806 unique trial opportunities were noted for MM and NHL, of which 9,513 were international and 22,293 were in the US, with a geographical distribution of 5080 in West, 8198 in Midwest, 3944 in Northeast, and 5071 in South. 4,883 of the unique trial opportunities were available at NCI/NCCN accredited sites and 17,410 were at non-NCI/NCCN sites in the US. Treatment characteristics of the trials included monoclonal antibodies in 1218, other targeted agents in 2641, stem cell transplant in 526, and other agents in 517 trials with several trials utilizing more than one of these therapeutic options. There was no statistically significant difference in the distribution of clinical trials by phase of study across various US geographical regions for MM (p=0.71), NHL (p=0.98) or combined MM+NHL (p=0.16). On the other hand, unique trial opportunities were significantly different by study phase and geographical distribution for MM, NHL or MM+NHL (all p<0.001) (Figure 3). Conclusions: Widespread access to clinical trials within a cancer diagnosis is imperative for generalizability of trial results. In a comprehensive, national analysis we noted that while it may appear that clinical trials are available across the US, sites where they are open are distributed unevenly, giving rise to a disparity in access to evidence-based therapeutic advancements for patients. Disclosures Ailawadhi: Janssen: Consultancy; Amgen: Consultancy; Pharmacyclics: Research Funding; Takeda: Consultancy; Celgene: Consultancy. Sher:Affimed: Research Funding.