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Background: The overall participation of cancer patients in interventional clinical trials in the United States remains very low, with ~5% of patients being enrolled in clinical trials nationwide. The outcomes of patients with MM have improved significantly over the past decade, but available data suggest that the participation rates for patients with MM is comparable to other cancers. The drivers of participation and the potential impact of clinical trial participation have not been systematically studied in MM. Patients and Methods: We identified 228 patients who were enrolled into clinical trials for initial therapy of newly diagnosed MM between 2004 and 2018, and 4 controls for each of these patients. Controls were patients with NDMM, who were diagnosed closest in time to the index patients and did not participate in an interventional treatment trial. Various baseline characteristics as well as overall survival were compared between the two groups. Results: The baseline characteristics of the two groups are as shown in the Table. Patients who entered clinical trials were more likely to be female, resided closer to the clinic, and were more likely to have a prior history of MGUS. They were more likely to have higher ISS Stage, and a higher serum LDH, but there was no difference in the FISH risk status. Other indices of disease burden such as lower hemoglobin and platelets, higher serum creatinine were all seen more often in the control group, but may have been influenced by the trial entry criteria. Looking at the outcomes, the overall survival was longer among those enrolled into clinical trials compared to those who did not [median 103 (95% CI; 86, 136) vs. 63 (95% CI; 53, 69) months, p<0.001 (Figure). Conclusions: The current study provides important clues regarding demographic determinants of trial participation and disease biology related features that reflect likelihood of trial participation. Overall survival was significantly longer among the trial participants, which likely represent a mix of reasons including baseline status of patients, intensity of monitoring and efficacy of novel treatment approaches. Table Disclosures Kapoor: Janssen: Research Funding; Celgene: Honoraria; Cellectar: Consultancy; Sanofi: Consultancy, Research Funding; Amgen: Research Funding; Glaxo Smith Kline: Research Funding; Takeda: Honoraria, Research Funding. Dispenzieri:Alnylam: Research Funding; Janssen: Consultancy; Pfizer: Research Funding; Takeda: Research Funding; Celgene: Research Funding; Akcea: Consultancy; Intellia: Consultancy. Gertz:Ionis: Honoraria; Alnylam: Honoraria; Prothena: Honoraria; Celgene: Honoraria; Janssen: Honoraria; Spectrum: Honoraria, Research Funding. Lacy:Celgene: Research Funding. Dingli:Karyopharm: Research Funding; Rigel: Consultancy; alexion: Consultancy; Janssen: Consultancy; Millenium: Consultancy. Leung:Omeros: Research Funding; Aduro: Membership on an entity's Board of Directors or advisory committees; Takeda: Research Funding; Prothena: Membership on an entity's Board of Directors or advisory committees. Russell:Imanis: Equity Ownership. Kumar:Takeda: Research Funding; Janssen: Consultancy, Research Funding; Celgene: Consultancy, Research Funding.

Introduction: There is a paucity of randomized trials to guide therapy for relapsed AL amyloidosis with treatment regimens generally extrapolated from experience in multiple myeloma. Methods: We conducted a retrospective review of patients who relapsed after receiving autologous stem cell transplant at Mayo Clinic. Patients treated for first relapse between January 2004 and December 2018 were included. Results: Three hundred and twenty-one patients were seen for relapsed AL amyloidosis post ASCT during the study period. Baseline characteristics were typical for a cohort with AL amyloidosis and are listed in Table1. 39% received therapy prior to transplant, conditioning in the majority (75%) was melphalan 200mg/m2. The median progression free survival from transplant (PFS1) was 30.7 months. Of the 321 patients 294 received treatment for relapsed disease. We categorized treatment regimens according to commonly used combinations and drug classes to further analyze outcomes. 34 patients were excluded from this analysis as they either proceeded directly to second ASCT (n=10) or received an atypical regimen not commonly considered for AL amyloidosis (n=24). Five categories of therapy regimens were identified, thalidomide based (n=110), melphalan plus steroids (n=31), 2nd generation immunomodulatory (IMiD) drug +/- alkylator (n=76), proteasome inhibitor (PI) +/- alkylator (n=116), PI plus IMiD (n=16), or daratumumab based (n=9). Disease and treatment characteristics for patients treated with these regimens are listed in Table 2. Patients treated with thalidomide had the shortest PFS1 (17.7 months) but PFS1 was similar for those treated with melphalan plus steroids, PI+IMiD and 2nd generation IMiDs (25.5, 24.3 and 25.6 months respectively). Patients treated with a PI +/- alkylator and daratumumab based regimen had the longest PFS1 (36.7 and 41.9 months respectively). The median duration of therapy was longer in patients treated with a 2nd generation IMiD or daratumumab based regimen (10.2, 12, 6.1, 5.5, 6.2 and 5.9 months for Dara based, 2nd generation IMiD, PI+/- alkylator, PI+IMiD, melphalan plus steroids and thalidomide based respectively). Hematologic response rate was lowest in those treated with melphalan plus steroids or thalidomide based regimens (44% and 55% respectively) and highest for patients treated with a PI+/- alkylator, (Figure 1). Progression free survival from relapsed therapy (PFS2) was longest amongst patients treated with daratumumab based regimens, PI +/- alkylator and 2nd generation IMiDs (not reached, 29.9 and 26.7 months respectively), Figure 2A. Overall survival from time of relapsed therapy favored patients treated with daratumumab based regimens, 2nd generation IMiDs and PI +/- alkylator, Figure 2b). Conclusion: A second generation IMiD based regimen or PI +/- alkylator produce high response rates and prolonged progression free and overall survival for relapsed AL amyloidosis. Patients treated with daratumumab based regimens and those treated with a PI plus IMiD also appear to do well, although numbers were low in our study. Patients treated with melphalan plus steroids or thalidomide based combinations have inferior outcomes and these regimens should be avoided. Disclosures Dispenzieri: Celgene: Research Funding; Takeda: Research Funding; Pfizer: Research Funding; Janssen: Consultancy; Intellia: Consultancy; Akcea: Consultancy; Alnylam: Research Funding. Lacy:Celgene: Research Funding. Dingli:Karyopharm: Research Funding; Rigel: Consultancy; Millenium: Consultancy; Janssen: Consultancy; alexion: Consultancy. Leung:Takeda: Research Funding; Prothena: Membership on an entity's Board of Directors or advisory committees; Aduro: Membership on an entity's Board of Directors or advisory committees; Omeros: Research Funding. Kapoor:Glaxo Smith Kline: Research Funding; Sanofi: Consultancy, Research Funding; Celgene: Honoraria; Cellectar: Consultancy; Amgen: Research Funding; Takeda: Honoraria, Research Funding; Janssen: Research Funding. Kumar:Takeda: Research Funding; Celgene: Consultancy, Research Funding; Janssen: Consultancy, Research Funding. Gertz:Medscape: Consultancy, Speakers Bureau; Prothena Biosciences Inc: Consultancy; Ionis/Akcea: Consultancy; Alnylam: Consultancy; Celgene: Consultancy; Janssen: Consultancy; Spectrum: Consultancy, Research Funding; Appellis: Consultancy; Amgen: Consultancy; Physicians Education Resource: Consultancy; Abbvie: Other: personal fees for Data Safety Monitoring board; Research to Practice: Consultancy; Teva: Speakers Bureau; Johnson and Johnson: Speakers Bureau; DAVA oncology: Speakers Bureau; Pharmacyclics: Membership on an entity's Board of Directors or advisory committees; Proclara: Membership on an entity's Board of Directors or advisory committees; i3Health: Other: Development of educational programs and materials; Springer Publishing: Patents & Royalties; Amyloidosis Foundation: Research Funding; International Waldenstrom Foundation: Research Funding; Annexon: Consultancy. OffLabel Disclosure: Daratumumab off label use for AL amyloidosis.

Background: c-MYC activation is an early event of myeloma pathogenesis. It upregulates the expression of the glutaminase 1 (GLS1) enzyme which converts glutamine to glutamate in the mitochondria. Glutamate is required for the biosynthesis of various molecules in the tricarboxylic acid (TCA) cycle (i.e., glutamine anaplerosis). CB-839 HCl is a first-in-class, orally available, selective, noncompetitive inhibitor of GLS1. This inactivation of GLS1 results in an increase of glutamine and a decrease of glutamate and several TCA cycle intermediates within cancer cells, leading to a decrease in their proliferation and/or an increase in cell death. In the phase 1 study, CX-839-002, the safety and tolerability of CB-839 HCl was evaluated in patients with hematological tumors (multiple myeloma (MM) and non-Hodgkin's lymphoma), either as monotherapy or in combination with pomalidomide and dexamethasone or with dexamethasone alone. It was determined to be well tolerated and the maximal tolerated dose (MTD) was not reached. Proteasome inhibitors (PI) are the cornerstone agents in the treatment of myeloma. They disrupt normal protein homeostasis causing an induction of cellular proteotoxic stress, thus, making it an effective strategy against myeloma plasma cells, which naturally mass-produce large quantities of immunoglobulin proteins. PI-resistant MM cells are associated with changes in cellular bioenergetics that favor the increased use of mitochondrial respiration for energy production. Given the increased reliance of PI-resistant MM cells on mitochondrial respiration, and the critical role of glutamine for cellular respiration, inhibition of glutamine metabolism is a rational molecular strategy for the treatment of PI-resistant MM. Furthermore, pre-clinical studies demonstrate the in vitro and ex vivo synergism of CB-839 HCl with carfilzomib (CFZ) in terms of its cytotoxicity and anti-proliferation capacity in various primary human myeloma cell lines and primary patient myeloma cells respectively. As a result, this novel combination of glutaminase inhibition with proteasome inhibition appears promising as a therapeutic combination in MM and warrants further clinical investigation. Methods: This study is a phase 1, multicenter clinical trial of CB-839 HCl in combination with carfilzomib and dexamethasone for patients with relapsed and/or refractory myeloma. Part A of this trial is a 3+3 dose escalation design and Part B is a dose expansion cohort at the RP2D determined in Part A. Up to a maximum of 42 patients will be enrolled at participating ETCTN sites. CFZ will be administered in its usual weekly dosing schedule of days 1, 8 and 15 of a 28 day schedule along with dexamethasone on days 1, 8, 15 and 22. CB-839 will be started at a dose level of 400 mg twice daily and will be investigated to a maximum dose of 800 mg twice daily. Prior to day 1 of Cycle 1, we will administer a 7 day lead in of CB-839 monotherapy before combining it with CFZ. Key inclusion criteria are having relapsed/refractory myeloma with at least 2 prior lines of therapy and prior exposure to PIs, immunomodulators and Anti-CD38 monoclonal antibodies, having measurable disease, adequate hematologic reserve, kidney function and liver function. Key exclusion criteria are being refractory or intolerant to CFZ, adverse cardiac history, central nervous system disease and AL amyloidosis. The primary objective of this trial is to determine the MTD or recommended phase II dosing (RP2D) of CB-839 HCl in combination with carfilzomib and dexamethasone. The secondary objective is to evaluate the safety and tolerability as well as the overall response rate (ORR) associated of CB-839 HCl in combination with carfilzomib and dexamethasone. Correlative objectives will evaluate plasma pharmacokinetic profiles of CB-839 HCl and carfilzomib when used in combination. They will also evaluate potential predictive and prognostic biomarkers as well as resistance mechanisms using genomic DNA, RNA, flow cytometry, immunohistochemistry and metabolomics-based assessment platforms. Recruitment is ongoing and this trial is registered on clinicaltrials.gov: NCT03798678. Disclosures Baz: Bristol-Myers Squibb: Research Funding; Sanofi: Research Funding; Karyopharm: 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; AbbVie: Research Funding; Merck: Research Funding. Neparidze:Janssen Scientific Affairs, LLC: Research Funding; Eidos Therapeutics: Other: Member of Independent Diagnostic Committee; MMRF/Synteract: Membership on an entity's Board of Directors or advisory committees. Kumar:Janssen: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Takeda: Research Funding.

Introduction: Daratumumab is a human immunoglobulin (IgG-κ) that targets CD38 abundantly expressed on plasma cells. Data is emerging to show its efficacy as part of induction therapy for newly diagnosed multiple myeloma (MM) patients. Hematopoietic stem cells have been shown to express CD38 on the cell surface and therefore during mobilization, there is a theoretical risk of circulating daratumumab binding to and having downstream effects on these cells. Methods: We conducted a retrospective review of MM patients treated with daratumumab prior to stem cell collection and autologous stem cell transplant (ASCT) to identify any effects daratumumab therapy may have on the efficacy of the stem cells in bone marrow recovery. The study was conducted at Mayo Clinic Rochester from February 2018 to May 2019. Granulocyte colony-stimulating factor was the preferred agent used for stem cell mobilization and plerixafor was added in a demand-adapted fashion. All patients received melphalan infused at day -1 before their ASCT and the decision about dosing (200mg/m2 vs 140mg/m2) was at the physicians' discretion. Neutrophil engraftment was defined as the first date of three consecutive neutrophil counts >0.5 x 10^9/L and platelet engraftment was defined as the first date of three consecutive platelet counts >50 x 10^9/L in the absence of platelet transfusion in the preceding 7 days. Results: We identified 12 patients who received daratumumab as part of their first induction regimen (daratumumab cohort) and compared them to 129 patients who did not receive daratumumab prior to stem cell mobilization and transplant during the study period (no daratumumab cohort). Of the daratumumab cohort, 11 patients received daratumumab, ixazomib, lenalidomide, and dexamethasone and one received daratumumab, cyclophosphamide, bortezomib and dexamethasone. No differences were noted in terms of melphalan dose or the number of CD34+ stem cell infused. The median time from the last dose of daratumumab to stem cell collection was 3.9 weeks. In patients receiving daratumumab, the median time for neutrophil engraftment was three days longer compared with those who did not receive daratumumab (median of 19 days vs. 16 days, P=0.017) (Figure 1, A). Median platelet engraftment was delayed by one day, although this was not statistically significant (median of 18 days vs. 17 days, p=0.12) (Figure 1, B). A total of 6 patients (50%) from the daratumumab cohort and 52 (40%) from the no daratumumab cohort required hospital admission. Of these admissions, there was no difference between the two groups in rates of admission for fever (50% in the daratumumab group vs. 42% in the no daratumumab group, P=0.7). Conclusion: Our case series provides the first report of daratumumab delaying engraftment post transplant in myeloma patients receiving it prior to stem cell collection. A better characterization of this phenomenon is important given the increasing use of daratumumab as front line therapy prior to ASCT in patients with myeloma. Disclosures Gertz: Prothena: Honoraria; Celgene: Honoraria; Janssen: Honoraria; Spectrum: Honoraria, Research Funding; Alnylam: Honoraria; Ionis: Honoraria. Lacy:Celgene: Research Funding. Kapoor:Sanofi: Consultancy, Research Funding; Glaxo Smith Kline: Research Funding; Cellectar: Consultancy; Janssen: Research Funding; Amgen: Research Funding; Takeda: Honoraria, Research Funding; Celgene: Honoraria. Dispenzieri:Alnylam: Research Funding; Celgene: Research Funding; Takeda: Research Funding; Pfizer: Research Funding; Janssen: Consultancy; Intellia: Consultancy; Akcea: Consultancy. Dingli:alexion: Consultancy; Janssen: Consultancy; Millenium: Consultancy; Rigel: Consultancy; Karyopharm: Research Funding. Kumar:Celgene: Consultancy, Research Funding; Janssen: Consultancy, Research Funding; Takeda: Research Funding.

Introduction: Proteasome inhibitors (PI), immunomodulatory agents (IMiDs) and the CD38 monoclonal antibody daratumumab (dara) have transformed the management of MM, yet eventual refractoriness to these agents seems inevitable. Relapsed and refractory MM (RRMM) which becomes triple class refractory (TCR, i.e. refractory to a PI, an IMiD and Dara) uncommonly responds to further lines of therapy and survival is dismal. Selinexor is a selective inhibitor of nuclear export compound targeting exportin 1 (XPO1) which is overexpressed in MM cells and essential for their survival. In the STORM study, selinexor in combination with low-dose dexamethasone (Sd) demonstrated promising efficacy in TCR, penta-exposed (TCR-PE, i.e. exposed to lenalidomide, pomalidomide, bortezomib, carfilzomib and dara) MM. Establishing the natural history for outcomes in the TCR-PE population can help provide context to understand the outcomes observed with Sd in STORM. In the retrospective MAMMOTH study, we reported the outcomes of patients with RRMM after they became refractory to dara, including a subset of patients who were TCR. We further analyzed the MAMMOTH dataset to generate a cohort of patients similar to patients in STORM in order to compare conventional care vs. Sd. Methods: We included all patients in STORM who received Sd as the first line therapy after they achieved TCR-PE status (n=64). We extracted from the MAMMOTH dataset all patients who were not exposed to Sd in a subsequent line of therapy, became TCR-PE and who received subsequent MM-directed therapy (n=128). Overall response rate (ORR) was evaluated according to IMWG criteria. Overall survival (OS) was calculated from the time of initiation of next line of therapy after TCR-PE status until death or last follow-up. We compared OS in STORM vs. MAMMOTH utilizing cox-regression analysis with adjustment for covariables potentially influencing the outcome. Results: Baseline patient characteristics and prior therapies are per table. The two cohorts were similar in terms of age, number of prior lines of therapy and presence of high-risk cytogenetic abnormalities. STORM patients had longer time between MM diagnosis and post TCR-PE therapy with a higher proportion of refractoriness to carfilzomib. Patients in STORM had ORR to Sd of 32.8% vs 25.0% for patients receiving conventional care in MAMMOTH (P=0.078). In direct comparison, patients in STORM had better OS than patients in MAMMOTH (median 10.4 vs. 6.9 months) (P=0.043, figure). In multivariate analysis, STORM patients had lower risk of death in comparison with MAMMOTH patients (aHR=0.55, 95%C.I. 0.35-0.86, P=0.009). Refractoriness to carfilzomib (aHR=2.20, 95%C.I. 1.16-4.15, P=0.015) and high-risk cytogenetics (aHR-1.66, 95% C.I. 1.13-2.42, P=0.009) were also associated with inferior OS. Conclusion: Despite inherent limitations in comparison of trial enrollees vs. real world patients, this analysis suggests improved OS with Sd vs conventional care in patients with TCR-PE RRMM. Prognosis for these patients remains poor and underscores the need for therapeutic advancements. Disclosures Costa: Janssen: Research Funding, Speakers Bureau; Celgene: Consultancy, Honoraria, Research Funding; Sanofi: Consultancy, Honoraria, Speakers Bureau; GSK: Consultancy, Honoraria, Research Funding; Abbvie: Consultancy; Karyopharm: Consultancy; Fujimoto Pharmaceutical Corporation Japan: Other: Advisor; Amgen: Consultancy, Honoraria, Research Funding, Speakers Bureau. Hari:Kite: Consultancy, Honoraria; Amgen: Research Funding; Spectrum: Consultancy, Research Funding; Sanofi: Honoraria, Research Funding; Janssen: Consultancy, Honoraria; BMS: Consultancy, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Takeda: Consultancy, Honoraria, Research Funding; Cell Vault: Equity Ownership; AbbVie: Consultancy, Honoraria. Kumar:Janssen: Consultancy, Research Funding; Takeda: Research Funding; Celgene: Consultancy, Research Funding. Tang:Karyopharm: Employment. Shah:Karyopharm Therapeutics Inc: Employment, Equity Ownership. Jagannath:BMS: Consultancy; Merck: Consultancy; Medicom: Speakers Bureau; Celgene: Consultancy; Novartis: Consultancy; Multiple Myeloma Research Foundation: Speakers Bureau. Chari:Oncoceutics: Research Funding; Novartis Pharmaceuticals: Research Funding; GlaxoSmithKline: Research Funding; Array Biopharma: Research Funding; Karyopharm: Consultancy, Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Millennium/Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol-Myers Squibb: Consultancy; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Sanofi: Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharmacyclics: Research Funding. Shacham:Karyopharm Therapeutics Inc: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties. Ma:Karyopharm: Employment, Equity Ownership. Siegel:Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Bristol-Myers Squibb Company: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Biran:Amgen: Consultancy, Honoraria, Research Funding; Merck: Research Funding; Janssen: Consultancy, Honoraria, Research Funding; Celgene: Consultancy, Honoraria; Takeda: Consultancy, Honoraria; Bristol Meyers Squibb: Research Funding. Lonial:BMS: Consultancy; Genentech: Consultancy; GSK: Consultancy; Janssen: Consultancy, Research Funding; Takeda: Consultancy, Research Funding; Amgen: Consultancy; Celgene Corporation: Consultancy, Research Funding; Karyopharm: Consultancy. Richardson:Amgen: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Sanofi: Membership on an entity's Board of Directors or advisory committees; Karyopharm: Membership on an entity's Board of Directors or advisory committees; Oncopeptides: 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; Takeda: Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol-Myers Squibb: Research Funding. Kauffman:Karyopharm Therapeutics Inc: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees. Malek:Adaptive: Consultancy; Amgen: Speakers Bureau; Janssen: Speakers Bureau; Celgene: Consultancy; Takeda: Consultancy; Sanofi: Consultancy; Medpacto: Research Funding. Fiala:Incyte: Research Funding. Usmani:Amgen, Celgene, Janssen, Sanofi, Takeda: Speakers Bureau; Amgen, Bristol-Myers Squibb, Celgene, Janssen, Merck, SkylineDX, Takeda: Other: Consultant/Advisor; Amgen Array Biopharma, Bristol-Myers Squibb, Celgene, Janssen, Merck, Pharmacyclics, Sanofi, Takeda: Other: Research Grant. Kang:Takeda Oncology: Consultancy; InCyte Corportation: Research Funding. Cornell:Takeda: Consultancy; KaryoPharm: Consultancy.

Introduction: Risk stratification of patients with light chain (AL) amyloidosis at diagnosis is invaluable. Currently, the Mayo 2012 staging system is mainly used to risk-stratify patients. We evaluated the role of increased mean corpuscular volume (MCV) at diagnosis in predicting survival. Methods: We conducted a retrospective study of patients with newly diagnosed AL amyloidosis seen at Mayo Clinic, Rochester between January 2006 through December 2015. The diagnosis of AL was confirmed with biopsy and the determination of organ involvement was according to consensus criteria. Staging was done according to the Mayo 2012 staging system and patients with stage III/IV were considered to have advanced stage disease. Patient and disease factors were compared for categorical and continuous variables using the χ2 and the Wilcoxon signed rank tests, respectively. Overall survival (OS) was defined as the time from diagnosis to death of any cause. Survival analysis was done using the Kaplan-Meier method. Results: A total of 1064 patients were identified and were divided into two groups: those with an MCV ≥ 96 fl (Elevated MCV, n=180) and those with an MCV <96 fl (Low MCV, n=884). The median age at diagnosis for the whole cohort was 64, with an interquartile range (IQR) of 57-71. Overall, 222 (23%) had Mayo 2012 stage 1, 199 (21%) had stage 2, 239 (25%) had stage 3, and 290 (31%) had stage 4 disease. Patients with an elevated MCV were more likely to be more than 65 years old compared to patients with a low MCV (61% vs. 44%, p<0.0001). They were also likely to have an advanced Mayo 2012 stage (68% vs. 53%, P=0.0008). The median OS was significantly lower in patients with an elevated MCV compared to patients with a low MCV (median PFS 13 months vs. 41 month, respectively, P<0.0001)(Figure 1). On a univariable analysis, predictors of OS were advanced Mayo 2012 stage (RR 3.26, P<0.001) and MCV ≥ 96 (RR 1.6, P<0.0001). On the multivariable analysis, both variables remained predictors of OS [advanced Mayo 2012 stage (RR 3.19, P<0.001) and MCV ≥ 96 (RR 1.3, P=0.016)]. Conclusion: The median OS was shorter by 28 months in newly diagnosed AL amyloidosis patients with an MCV ≥ 96 compared to patients with an MCV<96. An elevated MCV was predictive of shorter survival, independent of the Mayo Stage. This variable is easily available, measured in all newly diagnosed patients, and provides valuable prognostic information for the treating physician. Disclosures Dispenzieri: Intellia: Consultancy; Takeda: Research Funding; Pfizer: Research Funding; Janssen: Consultancy; Alnylam: Research Funding; Celgene: Research Funding; Akcea: Consultancy. Lacy:Celgene: Research Funding. Dingli:alexion: Consultancy; Janssen: Consultancy; Millenium: Consultancy; Rigel: Consultancy; Karyopharm: Research Funding. Leung:Takeda: Research Funding; Prothena: Membership on an entity's Board of Directors or advisory committees; Omeros: Research Funding; Aduro: Membership on an entity's Board of Directors or advisory committees. Kapoor:Sanofi: Consultancy, Research Funding; Celgene: Honoraria; Cellectar: Consultancy; Janssen: Research Funding; Amgen: Research Funding; Takeda: Honoraria, Research Funding; Glaxo Smith Kline: Research Funding. Gertz:i3Health: Other: Development of educational programs and materials; Alnylam: Consultancy; Celgene: Consultancy; Appellis: Consultancy; Teva: Speakers Bureau; Spectrum: Consultancy, Research Funding; Annexon: Consultancy; Springer Publishing: Patents & Royalties; Amyloidosis Foundation: Research Funding; Amgen: Consultancy; Medscape: Consultancy, Speakers Bureau; Physicians Education Resource: Consultancy; Abbvie: Other: personal fees for Data Safety Monitoring board; Research to Practice: Consultancy; Ionis/Akcea: Consultancy; Prothena Biosciences Inc: Consultancy; Janssen: Consultancy; International Waldenstrom Foundation: Research Funding; Proclara: Membership on an entity's Board of Directors or advisory committees; Johnson and Johnson: Speakers Bureau; Pharmacyclics: Membership on an entity's Board of Directors or advisory committees; DAVA oncology: Speakers Bureau. Kumar:Takeda: Research Funding; Celgene: Consultancy, Research Funding; Janssen: Consultancy, Research Funding.

Introduction: Vitamin D deficiency is common, with 25-50% of the population having levels below the optimal range (<20 ng/mL). Aside from its role in maintaining serum calcium and skeletal homeostasis, vitamin D has been shown to play an important role in regulation of differentiation, proliferation, apoptosis, metastatic potential and angiogenesis in a variety of malignancies. Low serum 25(OH)D levels have been associated with a worse prognosis in several malignancies, including colorectal and breast cancer, chronic lymphocytic leukemia and non-Hodgkin's lymphoma. Almost no data have been reported on vitamin D levels in light chain (AL) amyloidosis. We therefore measured vitamin D levels among AL patients and correlated levels at presentation to explore if vitamin D deficiency has any effect or association in this disease. Methods: Stored serum samples from 90 patients with newly diagnosed AL amyloidosis were obtained for vitamin D studies, which included 25-hydroxyvitamin D [25(OH)D], 1,25-dihydroxyvitamin D [1,25(OH)2D] and vitamin D binding protein (DBP). All vitamin D measurements were made by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Total 25(OH)D and 1,25(OH)2D was assessed as the additive sum of the 25(OH)D2/25(OH)D3 and 1,25(OH)2D2/1,25(OH)2D3 components, respectively. Clinical data was extracted from the electronic medical records. All calculations were made using JMP software (SAS, Cary, NC). Results: All patients were seen between June 2004 and September 2013. Median age was 63 [IQR 57-70]. Heart, kidney, nerve, liver and gastrointestinal amyloidosis was seen in 80%, 60%, 19%, 17% and 13% of patients, respectively. The median dFLC and bone marrow plasma cells were 28 (IQR 12-84) mg/dL and 10% (IQR 5-20%), respectively. The median serum 25(OH)D level was 20 ng/mL (IQR 10-29; normal >20 ng/mL), while the median serum level of 1,25(OH)2D was 23 pg/mL (IQR 14-37; normal 16-64 pg/mL for men; 16-78 pg/mL for women). 25(OH)D levels <20 ng/mL were strongly associated with renal involvement (84% renal involvement vs 42% of renal involvement for levels ≥20 ng/dL, P<0.001; Table). No other association with organ involvement was seen. Among all patients, heavy proteinuria (>5 gr/24-h) was strongly associated with low 25(OH)D, (P<0.001, Table). A weaker association was seen between 25(OH)D levels and estimated glomerular filtration rate (eGFR) (P=0.06). Seventy-eight percent of patients with 1,25(OH)2D levels below 20 pg/mL had renal involvement versus 48% in those with levels above 20 pg/mL (P=0.01). While heavy proteinuria was associated with 1,25(OH)2D (P=0.008), the association was stronger for eGFR, as no patient with an eGFR <30 ml/min/1.73 m2 had a 1,25(OH)2D level above 20 pg/mL (P<0.001). An association between vitamin D levels and low serum albumin was also seen, mainly in relation to 25(OH)D (Table). The median level of serum DBP was 58 μg/mL (IQR 36 - 120 μg/mL), significantly lower than the normal range (168-367 μg/mL). Low levels of 25(OH)D or 1,25(OH)2D were not associated with lower DBP levels. Surprisingly, patients with renal involvement had higher levels of DBP versus those without renal involvement (median 70.9 vs 48 μg/mL; P=0.03), although median levels were below normal in both groups. FISH data was available in 47 of patients (52%). Patients with 25(OH)D levels <20 ng/dL were less likely to harbor t(11;14) versus patients with 25(OH)D levels above this threshold (26% vs 64%, respectively; P=0.0095). A similar, but less significant association was seen between 1,25(OH)2D levels at a 20 pg/mL threshold and t(11;14) (35% vs 59%, P=0.09). Other associations between vitamin D and FISH abnormalities were not seen. Conclusions: Hypovitaminosis D is common among AL amyloidosis patients with renal involvement. In the general cohort, heavy proteinuria, reduced eGFR and low serum albumin were all associated with low circulating vitamin D levels. Although the majority of AL patients had low levels of DBP, urinary loss of DBP does not explain the low levels of vitamin D. Hypovitaminosis D is associated with non-t(11;14) disease, a finding which warrants further exploration. Disclosures Dispenzieri: Akcea: Consultancy; Intellia: Consultancy; Janssen: Consultancy; Pfizer: Research Funding; Takeda: Research Funding; Celgene: Research Funding; Alnylam: Research Funding. Lacy:Celgene: Research Funding. Dingli:Rigel: Consultancy; Karyopharm: Research Funding; Millenium: Consultancy; Janssen: Consultancy; alexion: Consultancy. Kapoor:Cellectar: Consultancy; Celgene: Honoraria; Sanofi: Consultancy, Research Funding; Amgen: Research Funding; Takeda: Honoraria, Research Funding; Janssen: Research Funding; Glaxo Smith Kline: Research Funding. Leung:Omeros: Research Funding; Aduro: Membership on an entity's Board of Directors or advisory committees; Prothena: Membership on an entity's Board of Directors or advisory committees; Takeda: Research Funding. Russell:Imanis: Equity Ownership. Kumar:Celgene: Consultancy, Research Funding; Janssen: Consultancy, Research Funding; Takeda: Research Funding. Gertz:Ionis/Akcea: Consultancy; Alnylam: Consultancy; Janssen: Consultancy; Celgene: Consultancy; Annexon: Consultancy; Prothena Biosciences Inc: Consultancy; Spectrum: Consultancy, Research Funding.

Background: POEMS syndrome is a rare paraneoplastic syndrome caused by an underlying plasma cell disorder. The combination of a proteasome inhibitor, an IMiD and corticosteroid is known to be highly effective among patients with myeloma. Methods: We conducted a pilot using a 28-day oral regimen of ixazomib (4 mg days 1, 8, 15), lenalidomide (25 mg days 1-21), and dexamethasone (20 mg days 1, 8, 15, 22). Aspirin and acyclovir were used for prophylaxis. Eligibility included a diagnosis of POEMS syndrome, a plasma VEGF 2x normal, a PS < 3. There were two groups [gp] (intended enrollment 15 per gp): Gp 1, 3 cycles for pts destined for high-dose chemotherapy with stem cell transplant; Gp 2, 13 cycles for patients (pts) who had relapsed or refractory disease. Primary endpoint was VEGF complete response (CR=normalization) after 3 cycles. Secondary endpoints included safety, hematologic response, and overall survival at 3 and 12 months. Other domains including PET response (50% reduction in sum of SUVmax from baseline), clinical responses including neurologic response were also studied. Neurologic assessments were done using the modified neurological impairment score (mNiS+7POEMS), the overall neuropathy limitation scale, and the polyneuropathy disability score. To date, 13 pts enrolled since 10/31/2016-4 to Gp 1 and 9 to Gp 2. 11 pts were analyzed (2 dropped out before receiving any therapy). Data were frozen as of 07/15/2019. Results: Median age was 55; 73% were male. Of the evaluable patients, three were newly diagnosed (Gp 1), and 8 had relapsed or refractory disease (Gp 2). 72% met primary endpoint of VEGF CR (Table). At 3 months, the following improvements were seen: VEGF, 10/11; hematologic, 1/3; PET 1/3; neurologic impairment score, 3/11. By 12-months according to the modified nerve impairment scale, 3/6 had achieved objective improvement and 2/6 stable disease. With a median follow-up of 16 months, 2 patients have died of progressive disease and another patient progressed on therapy (Gp 2) with an extravascular leak progression. 27% of patients had grade 3+hematologic AE; 81% had grade 3-4 non-hematologic AE. These included: rash, respiratory infection, diarrhea, and hypotension in 2 each; atrial fibrillation, edema, dyspnea, and thromboembolism in 1 each. 5 pts had non-objective worsening of their neuropathy. Conclusions: These preliminary results suggest that Ixa-Len-Dex is an effective and tolerable regimen for patients with POEMS syndrome. Longer follow-up will be important to determine durability of this approach and for neurologic assessment given the slow rate of remyelination. Figure Disclosures Dispenzieri: Akcea: Consultancy; Intellia: Consultancy; Janssen: Consultancy; Pfizer: Research Funding; Takeda: Research Funding; Celgene: Research Funding; Alnylam: Research Funding. Lacy:Celgene: Research Funding. Kapoor:Cellectar: Consultancy; Janssen: Research Funding; Glaxo Smith Kline: Research Funding; Takeda: Honoraria, Research Funding; Sanofi: Consultancy, Research Funding; Celgene: Honoraria; Amgen: Research Funding. Leung:Takeda: Research Funding; Prothena: Membership on an entity's Board of Directors or advisory committees; Aduro: Membership on an entity's Board of Directors or advisory committees; Omeros: Research Funding. Dingli:alexion: Consultancy; Karyopharm: Research Funding; Rigel: Consultancy; Millenium: Consultancy; Janssen: Consultancy. Kumar:Takeda: Research Funding; Celgene: Consultancy, Research Funding; Janssen: Consultancy, Research Funding. Gertz:Proclara: Membership on an entity's Board of Directors or advisory committees; Springer Publishing: Patents & Royalties; Research to Practice: Consultancy; Physicians Education Resource: Consultancy; Abbvie: Other: personal fees for Data Safety Monitoring board; Ionis/Akcea: Consultancy; Alnylam: Consultancy; Prothena Biosciences Inc: Consultancy; Celgene: Consultancy; Janssen: Consultancy; Spectrum: Consultancy, Research Funding; Annexon: Consultancy; DAVA oncology: Speakers Bureau; Pharmacyclics: Membership on an entity's Board of Directors or advisory committees; i3Health: Other: Development of educational programs and materials; Amyloidosis Foundation: Research Funding; International Waldenstrom Foundation: Research Funding; Teva: Speakers Bureau; Johnson and Johnson: Speakers Bureau; Appellis: Consultancy; Amgen: Consultancy; Medscape: Consultancy, Speakers Bureau. OffLabel Disclosure: No drugs approved for POEMS syndrome. Ixazomib, lenalidomide and dexamethasone

Introduction: Daratumumab, a CD38-directed monoclonal antibody, in combination with lenalidomide and dexamethasone (D-Rd), recently received FDA approval for the treatment of patients with newly diagnosed multiple myeloma (NDMM) ineligible for autologous stem cell transplantation (ASCT). FDA approval was based on results of the prespecified interim analysis of a pivotal phase III trial (MAIA) in which D-Rd was compared to Rd among patients with NDMM who were ineligible for ASCT. In the MAIA trial, D-Rd significantly reduced the risk of progression or death compared to Rd. However, no trials have compared D-Rd to other standard-of-care (SOC) regimens. The present study compared progression-free survival (PFS) of D-Rd from the MAIA trial database to common SOC regimens from the Flatiron Health EHR Database, a de-identified nationwide US database of records primarily from community-based oncology practices. Methods: Patient-level data were obtained from the MAIA trial and the Flatiron database. Patients in the MAIA trial were enrolled between March 2015 and January 2017. To be included in MAIA, patients had to be deemed ineligible for high-dose chemotherapy with ASCT due to either age (≥65 years) or presence of comorbidities, have Eastern Cooperative Oncology Group performance status (ECOG PS) ≤2, creatinine clearance ≥30mL/min, and adequate bone marrow reserve. In the Flatiron Database, patients had to be diagnosed with MM between January 2011 and April 2019, age ≥65 years at initiation of first line treatment (LOT1), could not have received stem cell transplant as part of LOT1, and met MAIA inclusion/exclusion criteria. Regimens received by fewer than 10% of patients in Flatiron were excluded due to sample size and statistical power considerations. Bortezomib-lenalidomide-dexamethasone (VRd), bortezomib-dexamethasone (Vd), and Rd were the most commonly used regimens in non-transplant NDMM patients, representing 67% of regimens used in this setting. Multiple imputation by chained equations was used to address missing data in Flatiron. Eligible Flatiron patients treated with VRd, Vd, or Rd as LOT1 were reweighted to resemble the MAIA trial population on measured baseline characteristics using propensity-score (PS) weighting. An anchored adjusted indirect treatment comparison (ITC) was performed to compare D-Rd to VRd and D-Rd to Vd, using a stratified Cox proportional hazards regression model with Rd as the common anchor across both data sources. The model calculates hazard ratios (HRs) for direct comparisons within MAIA (D-Rd vs Rd) and within Flatiron (VRd vs. Rd, Vd vs. Rd) to estimate the HRs indirectly for D-Rd vs. VRd and D-Rd vs. Vd. Results: After application of MAIA inclusion criteria and PS-reweighting, the Flatiron VRd, Rd, and Vd patients resembled the MAIA trial population on baseline patient demographics and clinical characteristics (Table 1). D-Rd statistically significantly reduced the risk of progression or death compared to Rd (HR=0.55; 95% CI, 0.41-0.72) based on the direct comparison with D-Rd using the MAIA trial data; D-Rd statistically significantly reduced the risk of progression or death compared to VRd (HR=0.66; 95% CI, 0.46-0.95) and Vd (HR=0.47; 95% CI, 0.33-0.67) based on the anchored ITC (Figure 1). Sensitivity analyses will be performed and updated analysis using longer follow-up data from the MAIA study will be presented at the meeting. Conclusion: This analysis demonstrated that D-Rd reduced the risk of progression or death compared to other SOCs VRd and Vd for patients with NDMM who are transplant-ineligible. In the absence of head-to-head trials, this type of patient-level analysis provides important information that can help optimize treatment for patients with NDMM who are transplant-ineligible. Disclosures Durie: Amgen, Celgene, Johnson & Johnson, and Takeda: Consultancy. Kumar:Takeda: Research Funding; Janssen: Consultancy, Research Funding; Celgene: Consultancy, Research Funding. Usmani:Amgen, Celgene, Janssen, Sanofi, Takeda: Speakers Bureau; Amgen Array Biopharma, Bristol-Myers Squibb, Celgene, Janssen, Merck, Pharmacyclics, Sanofi, Takeda: Other: Research Grant; Amgen, Bristol-Myers Squibb, Celgene, Janssen, Merck, SkylineDX, Takeda: Other: Consultant/Advisor. Ammann:Janssen: Employment, Equity Ownership. Lam:Janssen: Employment, Equity Ownership. Kobos:Janssen: Employment. Maiese:Janssen: Employment, Equity Ownership. Facon:Celgene: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Takeda: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Amgen: Membership on an entity's Board of Directors or advisory committees; Sanofi: Membership on an entity's Board of Directors or advisory committees.

Background: A variety of risk factors have been described in multiple myeloma and current risk assessment incorporates ISS stage with specific FISH results and serum LDH (R-ISS). However, this model does not include all the current abnormalities described as prognostic for survival in multiple myeloma. Importantly, the impact of many of these high-risk abnormalities are not uniform. We examined if we can better integrate FISH results into a risk assessment tool to better predict the outcomes of newly diagnosed MM. Patients and methods: We studied a cohort of 1316 patients with FISH done within 6 months of diagnosis of MM, in whom results for commonly observed abnormalities were available. We specifically examined the individual impact of common translocations involving chromosome 14, MYC rearrangements, chromosome 1q gain (single or multiple duplication) and del13q/monosomy 13. A risk assessment system was developed, weighting each abnormality according to their Risk Ratio and integrating ISS stage and serum LDH into the final model construction. Overall survival was calculated from diagnosis, with those alive at last follow up being censored. Results: We first examined the impact of each of the above FISH abnormalities: 1) high risk translocations [t(4;14), t(14;16), or t(14,20)], 2) trisomies, 3) t(11;14), 4) MYCrearrangements, 5) del13q/monosomy 13, and 6) 1q gain . Each of the abnormalities, except for t(11;14), was prognostic for survival (Table 1 with the risk ratios). For 1q gain, the median OS was NR, 105 mos and 79 mos respectively for no abnormality, duplication of 1 copy and duplication of multiple copies, (p<0.001). On multivariate analysis, t(11;14) and trisomies were no longer prognostic for overall survival (Table 1). The cumulative impact of abnormalities demonstrated worsening survival in the presence of increasing numbers of abnormalities (Figure 1). Including ISS stage 3 and LDH > ULN as additional variables for prognostication indicated both were individually prognostic for OS. In a multivariate analysis, including these two and FISH abnormalities, 1q gain and LDH were not independently prognostic. The final model consisted of HR translocations, MYCrearrangements, del17p/monosomy 17, del13q/monosomy 13, and ISS stage 3. Each of these variables was weighted using their risk ratio and a composite score was developed using 998 patients for whom all variables were available (range: 0-7.9; median 1.8). Three patient groups were characterized: group 1 (0; 32%), group 2 (1-4; 58%) and group 3 (>4; 10%) with a median OS of 53 mos, 106 mos, and NR, respectively, p <0.001 (Figure 2). Conclusion: Using the most relevant FISH and laboratory factors, in a large cohort of patients, we refined the current system to develop a risk stratification system that predicts survival in patients with newly diagnosed MM treated with contemporary treatment regimens. This needs validation in future studies. Disclosures Kumar: Janssen: Consultancy, Research Funding; Takeda: Research Funding; Celgene: Consultancy, Research Funding. Gertz:International Waldenstrom Foundation: Research Funding; Annexon: Consultancy; Medscape: Consultancy, Speakers Bureau; Amyloidosis Foundation: Research Funding; Abbvie: Other: personal fees for Data Safety Monitoring board; i3Health: Other: Development of educational programs and materials; Springer Publishing: Patents & Royalties; Physicians Education Resource: Consultancy; Pharmacyclics: Membership on an entity's Board of Directors or advisory committees; Proclara: Membership on an entity's Board of Directors or advisory committees; Ionis/Akcea: Consultancy; Alnylam: Consultancy; Prothena Biosciences Inc: Consultancy; Celgene: Consultancy; Janssen: Consultancy; Spectrum: Consultancy, Research Funding; Appellis: Consultancy; Research to Practice: Consultancy; Teva: Speakers Bureau; Johnson and Johnson: Speakers Bureau; DAVA oncology: Speakers Bureau; Amgen: Consultancy. Dispenzieri:Akcea: Consultancy; Janssen: Consultancy; Intellia: Consultancy; Pfizer: Research Funding; Takeda: Research Funding; Celgene: Research Funding; Alnylam: Research Funding. Lacy:Celgene: Research Funding. Dingli:alexion: Consultancy; Janssen: Consultancy; Millenium: Consultancy; Rigel: Consultancy; Karyopharm: Research Funding. Kapoor:Celgene: Honoraria; Janssen: Research Funding; Sanofi: Consultancy, Research Funding; Glaxo Smith Kline: Research Funding; Takeda: Honoraria, Research Funding; Amgen: Research Funding; Cellectar: Consultancy. Leung:Prothena: Membership on an entity's Board of Directors or advisory committees; Takeda: Research Funding; Omeros: Research Funding; Aduro: Membership on an entity's Board of Directors or advisory committees. Bergsagel:Celgene: Consultancy; Ionis Pharmaceuticals: Consultancy; Janssen Pharmaceuticals: Consultancy.