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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 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.

Abstract Abstract 332 Background: The high response rates seen with the bortezomib, lenalidomide, and dexamethasone (VRD/RVD) regimen (Kumar S, et al. Blood 2012; Richardson PG, et al. Blood 2010) highlight the feasibility of combining a proteasome inhibitor with an immunomodulatory agent and a steroid in patients with previously untreated multiple myeloma (MM). MLN9708 is an investigational, oral, reversible proteasome inhibitor with promising anti-MM effects and favorable toxicity profile with low rates of peripheral neuropathy (PN). Here we report phase (Ph) 1 and preliminary Ph 2 results of the first study of MLN9708 in combination with lenalidomide and dexamethasone in patients with previously untreated MM (NCT01217957). Methods: Patients aged ≥18 yrs with measurable disease, ECOG performance status 0–2, and no grade ≥2 PN, received oral MLN9708 (days 1, 8, and 15) plus lenalidomide 25 mg (days 1–21) and dexamethasone 40 mg (days 1, 8, 15, 22) for up to twelve 28-day cycles, then maintenance therapy with MLN9708 (same schedule) every 28 days until progression. Patients could undergo stem cell collection after 3 cycles and discontinue for autologous stem cell transplant (ASCT) after 6 cycles. In Ph 1, dose escalation (1.68–3.95 mg/m2) proceeded using a standard 3+3 design, based on cycle 1 dose-limiting toxicities (DLTs). Ph 1 primary objectives were determination of safety, maximum tolerated dose (MTD), and recommended Ph 2 dose (RP2D); the Ph 2 primary objective was CR+VGPR rate. Secondary and exploratory objectives included characterization of MLN9708 pharmacokinetics (PK) and measurement of minimal residual disease using multiparameter flow cytometry. Responses were assessed by IMWG criteria. Adverse events (AEs) were graded by NCI-CTCAE v4.02. Results: From 22 November 2010 (Ph 1) and 14 October 2011 (Ph 2) to data cut-off (June 27, 2012), 65 patients (36 male) have been enrolled, 15 in Ph 1 and 50 in Ph 2. Median age was 66 yrs (range 34–86); 43% and 13% had ISS stage II and III. Patients have received a median of 5 cycles (range 1–15) – 6 cycles (range 1–15) in Ph 1 and 5 cycles (range 1–8) in Ph 2. 42 (65%) patients remain on treatment, 4 (27%) in Ph 1 and 38 (76%) in Ph 2. At 10 August 2012, 22 patients have discontinued: 16 to receive ASCT, 4 due to AEs (3 drug-related, 1 not drug-related GI bleed), 2 for other reasons (1 disease progression, 1 due to investigator decision). Of those who have undergone stem cell mobilization, a median yield of 9.1 × 106 CD34+ cells/L was reported. MLN9708 MTD was established as 2.97 mg/m2 and RP2D was selected as 2.23 mg/m2; RP2D converts to a 4.0 mg fixed dose based on population PK results. At 27 June, all-grade AEs related to any regimen drug and seen in ≥25% of patients were fatigue (32%), nausea (31%), and vomiting (25%). Grade 3 any-drug-related AEs were reported in 26 (40%) patients, including erythematous rash, nausea and vomiting (5% each). Grade 4 any-drug-related AEs were end-stage renal disease (related to progressing MM) and deep vein thrombosis in 1 patient each. One patient experienced grade 3 PN at the RP2D. At 10 August, 3 patients discontinued due to drug-related AEs – 1 in Ph 2 who stopped due to grade 1 resting tremor, grade 2 occasional memory loss (neurologic work-up was negative), and grade 2 peripheral sensory neuropathy, 1 patient in Ph 2 due to drug-related RSV pneumonia who subsequently died on study due to this AE, and 1 patient in Ph 1 with syncope (a DLT). Among all 65 patients (at 10 August), median patient follow-up was 3.88 months (Ph 1: 9.03 months, Ph 2: 3.68 months). The overall response rate (ORR; ≥PR, confirmed/unconfirmed) was 88% (100% in Ph 1 and 84% in Ph 2); this includes 40% ≥VGPR (53% in Ph 1 and 36% in Ph 2) and 18% CR (33% in Ph 1 and 14% in Ph 2). Median cycle number is limited, but 50 patients have received ≥4 cycles: ORR was 96%, with 44% ≥VGPR and 26% CR. Analyses by cytogenetic status will be presented at the meeting. At data cut-off, 50 of 52 responders remained in response, with responses durable for up to 13.2+ months. Median time to first response was 0.92 months (range 0.89–6.44). Conclusions: The combination of weekly oral MLN9708 plus lenalidomide and dexamethasone appears generally well tolerated, with one grade 3 PN at the RP2D. Preliminary data show antitumor activity at the RP2D in patients with previously untreated MM, and at data cut-off, 96% of patients had achieved ≥PR, including a ≥VGPR rate of 44% and a CR rate of 26%, with responses consistent with those reported with VRD/RVD. Disclosures: Kumar: Millennium Pharmaceuticals, Inc.: Research Funding; Novartis: Research Funding; Genzyme: Research Funding; Cephalon: Research Funding; Merck: Consultancy, Honoraria; Celgene: Consultancy, Research Funding. Off Label Use: A study of the investigational agent MLN9708 in combination with lenalidomide and dexamethasone for the treatment of patients with previously untreated multiple myeloma. Niesvizky:Celgene: Consultancy, Research Funding, Speakers Bureau; Millennium Pharmaceuticals, Inc.: Consultancy, Research Funding, Speakers Bureau; Onyx Pharmaceuticals: Consultancy, Research Funding, Speakers Bureau. Lonial:Onyx: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Bristol-Meyers Squibb: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Millennium Pharmaceuticals, Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees; Merck: Consultancy, Membership on an entity's Board of Directors or advisory committees. Stewart:Millennium Pharmaceuticals, Inc.: Consultancy, Research Funding. Hari:Celgene: Consultancy. Vescio:Millennium Pharmaceuticals, Inc.: Speakers Bureau. Berg:Millennium Pharmaceuticals, Inc.: Employment. Lin:Millennium Pharmaceuticals, Inc.: Employment. Di Bacco:Millennium Pharmaceuticals, Inc.: Employment. Gupta:Millennium Pharmaceuticals, Inc.: Employment. Hui:Millennium Pharmaceuticals, Inc.: Employment. Richardson:Millennium Pharmaceuticals, Inc.: Membership on an entity's Board of Directors or advisory committees; Janssen Pharmaceuticals and Janssen-Cilag: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees.

Abstract 5079 Introduction: IgD monoclonal proteins are rare. They are not seen as a MGUS and are present in 1% to 2% of patients with myeloma. In light chain amyloidosis (AL), IgD monoclonal proteins are rare. When an IgD protein is found, amyloidosis is often omitted from the differential diagnosis. An IgD protein in amyloidosis has been reported in single cases but never as a patient series. We report IgD AL in 53. Patients & Methods: Clinical and demographic data for patients were retrieved from the patient records. Factors of interest were compared between patients who did and did not have an IgD protein. Results: Among 3,955 patients with AL amyloidosis seen, 53 patients (1.3%) had a serum IgD monoclonal protein. (Table 1) A serum monoclonal protein peak was visible on SPE in only 14, and only 5 had an M spike greater than 1 g/dL. On immunofixation of the serum, the IgD light chain was k in 11, λ in 35, and uncertain in 6; 1 patient had a biclonal D λ and G k protein. A urine monoclonal protein was detected in 43 of 51 patients; urinary immunofixation detected a λ light chain in 33 and a k light chain in 10. Biopsy of tissues showed amyloid deposits in the bone marrow in 47% and in the fat aspirate in 73%. Six patients (age 47–63 years) underwent autologous SCT. Four had renal & two had cardiac AL. All 6 had hematologic PR, 4 CR, and 4 had organ response. One patient had relapse of disease and is now on dialysis, and another had relapse and is alive with salvage chemotherapy. One patient had disease relapse and died of progressive GI amyloidosis at 22 months. The other 5 are alive at a median of 68 months (range, 7.5–83.5 months). We compared the 53 patients with IgD amyloidosis with 144 patients with non-IgD amyloidosis. (Table 2) Findings that were significantly different between groups included a lower frequency of renal amyloidosis (P=.005) and a lower prevalence of cardiac amyloidosis (P=.047). There was a higher serum albumin level (P=.04) related to the lower level of proteinuria. No difference in survival was seen between the groups. (Figure). Variables that might affect survival—liver size, performance status, septal thickness, serum creatinine level, and β2-microglobulin level—were not different between groups. Conclusions: IgD AL patients have a lower frequency of renal involvement and possibly also of cardiac involvement. The overall survival of these patients does not appear to be different from that of patients who have AL associated with another monoclonal protein. IgD monoclonal proteins are so closely linked to the diagnosis of multiple myeloma in the mind of a clinician that the possibility of amyloidosis may be overlooked. Disclosures: No relevant conflicts of interest to declare.

Abstract Background Multiple myeloma (MM) is the second most common hematologic malignancy in the U.S. and is characterized by increased immunoglobulin production and infiltration of the bone marrow by malignant plasma cells. Myeloma cell growth is supported by both the elements present in the bone marrow microenvironment as well as deregulation of internal cellular systems associated with proliferation and apoptosis. Defective programmed cell death by BCL2 or MCL1 upregulation is observed in >80% of myeloma cases and is associated with an aggressive clinical course. Remarkably, there is no approved drug with the ability to target BCL2 or MCL1. Various strategies to mitigate the effects of increased BCL2 functionality, via small molecule inhibitors or BCL2-specific antisense oligonucleotides have been previously examined in MM. These studies revealed that 1) apart from BCL2, additional anti-apoptotic members belonging to the BCL2 family (i.e. MCL1, BCL-xL) play integral roles in maintenance of the myeloma cell phenotype, 2) drugs, which target only BCL2 offer limited therapeutic advantage and 3) given that survival factors engaged in MM are multifactorial, perhaps isolated targeting of the BCL2 pathways may not be sufficient. We therefore hypothesized that the clinical development of drugs that target various antiapoptotic BCL2 family members will require a partnership with established anti-MM regimens whose activity can potentially be further enhanced with correction of the apoptotic response system. Aim Since lenalidomide and dexamethasone (LD) is an established therapy for plasma cell cancers, we investigated if the pan-BCL2 inhibitor AT-101 (BH3 mimetic), which has high binding specificity for BCL2, MCL1 and BCL-xL, can be an effective therapeutic partner to enhance anti-MM effects of LD. Methods Human MM (KMS11, U266, OPM2) and WM (BCWM.1) cell lines along with their corresponding bortezomib resistant (BR) clones, (KMS11/BR, U266/BR, OPM2/BR and BCWM.1/BR) which were developed in our laboratory were used in this study. For gene expression profiling, the Illumina HumanHT-12 v3 whole-genome gene expression array and Nanostring nCounter mRNA quantification assays (NanoString, Seattle, WA) were utilized. Statistical analysis was conducted using R-based packages and the MeV software (TIGR). Apoptosis was measured by annexin-v/PI staining, and mitochondrial membrane permeability (MOMP) was assessed using TMRM followed by flow cytometry. Protein profiles were ascertained by western blot. Results Gene expression and immunoblot analysis of six plasma cell cancer models showed upregulation of various BCL2 family members, notably MCL1 and BCL-xL. In a dose-dependent manner, AT-101 was able to downregulate BCL2 and MCL1 and induced apoptotic cell death in MM and WM cells in a dose dependent manner. Tumor cell death was associated with caspase and PARP-1 cleavage accompanied by an increase in MOMP. This cytotoxic effect and BCL2 downregulation were further potentiated when AT-101 was combined with lenalidomide/dexamethasone (LDA). Nanostring nCounter mRNA quantification and IPA analysis revealed differential changes in the CCNA, FRZB, FYN, IRF1, PTPN11 genes in LDA treated cells. IPA canonical pathway analysis demonstrated the p53 signaling and the cyclins and cell cycle regulation pathways to be the most significantly activated by LDA therapy. Summary In summary, we describe for the first time the cellular and molecular events associated with the use of AT-101 in combination with lenalidomide/dexamethasone in preclinical models of plasma cell malignancy. This study lays the rationale for engaging and handicapping the intrinsic apoptotic system through the pan-BCL2 targeting capabilities of AT-101; thus enhancing the anti-MM effects of lenalidomide/dexamethasone. Disclosures: Foran: Celgene: Research Funding.

Abstract Background Pomalidomide (POM) is the newest Immunomodulatory agent (IMiDs) that has shown clinical efficacy in relapsed multiple myeloma (MM) refractory to lenalidomide (LEN) and thalidomide (THAL). Studies of MM cell microenvironment suggest that tumor subclones compete for dominance during changes in drug therapy. It was previously observed that a minor clonal population increased in prominence of MM cells after 1 year of treatment with LEN. We examined whether the patients having THAL or LEN as the most recent prior-line therapy affects response to POM. Methods We studied 208 patients enrolled in a phase II trial of POM / dexamethasone between November 2007 and March 2012 at Mayo Clinic, Rochester. We reviewed the immediate prior-line therapy before enrollment in our trial. Comparison of treatment duration of POM and response rates were conducted between patients who had either THAL or LEN as latest prior-line therapy, and patients who were treated with non-IMiDs immediate before enrollment in POM trial. Treatment duration of POM was estimated using Kaplan Meier method and the survival curves were compared using log-rank test. We used univariate Cox proportional hazard models to estimate the prognostic impact of different variables. Results The median age of patients was 63 (range from 32 to 88). 68 % were males. 80 patients (38.5%) had THAL or LEN immediate prior to POM. Median prior-line therapies were 3. Patients who received THAL or LEN immediately prior to POM had a lower response rate than those who had non-IMiDs as latest therapy (29% vs 44%, p 0.04) and shorter median duration of POM treatment (5.7 months vs 7.3 months, p 0.02). In 190 (91%) patients who were previously treated with LEN and THAL at any time, median time between the end of LEN or THAL treatment and the initiation of POM was higher for POM responders than non-responders (10 months vs 3 months, p 0.0008). Patients responded to POM had a shorter duration of prior LEN or THAL treatment compared to non-responders (9 months vs 15 months, p 0.001). Conclusion THAL or LEN as an immediate prior-line therapy to POM is associated with a lower response rate and shorter effective treatment duration. Longer interval between prior immunomodulatory compounds and POM, and shorter exposure to previous immunomodulatory compounds are associated with better POM treatment response. Disclosures: Gertz: Celgene: Honoraria. Kumar:Merck: Consultancy, Honoraria; Celgene: Consultancy, Research Funding; Millennium: The Takeda Oncology Company: Research Funding; Novartis: Research Funding; Genzyme: Research Funding. Lacy:Celgene Corporation: Research Funding.