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Background: MM is associated with significant morbidity even at the time of presentation and there is ample data to support that MM treatment improves overall survival (OS) as well as quality of life (QoL) due to effective symptom control. Patient refusal to recommended cancer treatment is not common in clinical practice but has been reported in certain cancers. There is no data on characteristics of MM patients who refuse treatment despite physician recommendation and outcomes of such patients. Methods: We used the National Cancer Database (NCDB) from 2004-2015 to extract data on adult MM patients who refused any systemic therapy as part of their initial care despite physician recommendation. Information on patient age, gender, race/ethnicity, education, year of diagnosis, income, geographical location, comorbidities, systemic treatment, survival time and vital status was obtained. Average annual percent change (AAPC) and average percent change (APC) were calculated to analyze the trends, and periods with similar APC were compared for statistically significant changes by applying join point regression. Multivariate models were employed to identify factors predicting refusal to therapy and to assess its impact on OS. Results: Of 75,734 eligible patients who were recommended treatment for MM (chemotherapy and or immunotherapy), 2138 (2.8%) patients did not receive any treatment due to refusal. Significantly higher number of females, patients in older age groups (age groups 60-79 and ³ 80 years), Medicare recipients and with ≥2 comorbidities refused treatment recommendation. On multivariate analysis, advanced age groups 60-79 years (OR = 1.47; 95% CI 1.27-1.31 p<0.001) and ³80 years (OR = 5.02; 95% CI 4.23-5.96, p<0.001), female gender (OR =1.16 ; 95% CI 1.05-1.27, p<0.001), patients with certain primary payor types including Medicaid (OR = 1.59; 95% CI 1.28-1.98, p<0.001), Medicare (OR = 1.63; 95% CI 1.43-1.87, p<0.001) and uninsured (OR = 1.81; 95% CI 1.38-2.38, p<0.001), and presence of ³2 comorbidities (OR = 1.39; 95% CI 1.2-1.61, p<0.001) were the independent factors associated with higher likelihood of refusing treatment. Whereas being seen at academic research programs (OR = 0.7; 95% CI 0.6-0.8, p<0.001), higher education (OR =0.81 ; 95% CI 0.67-0.98, p=0.03), geographical location (Midwest OR =0.87 ; 95% CI 0.76-0.99, p=0.04), longer distance to facility being at 3rd quartile (10.1-26.2 miles: OR =0.78 ; 95% CI 0.68-0.89, p<0.001) or 4th quartile (>26.2 miles: OR = 0.59; 95% CI 0.51-0.68, p<0.001) were associated with lower likelihood of refusing treatment. The overall rate of refusing treatment by MM patients was quite stable during 2004-2015 with an AAPC of 1.1 (95% CI -1.1-3.3 p=0.3). However, on fitting scatter plot into Joinpoint regression model, a concerning trend in the more recent years was noted. While the rate of refusing recommended treatment decreased during 2004-2008, a rising trend was observed during the period 2008-2015 with an APC of 3.8 (95% CI 1.3-6.4, p≤0.001) (Fig 1a). Patients who were recommended treatment but refused had significantly worse survival than those who received treatment (median survival 17.7 vs 52.9 months, Cox hazard ratio 1.21; CI 1.17-1.24, p<0.001) (Fig 1b). Conclusions: The percentage of MM patients refusing any systemic treatment as a part of their initial care despite physician recommendation appears to be increasing in recent years and this needs to be systematically addressed. Disparities in refusal to recommended treatment are independently associated with several variables including age, gender, comorbidities, geographical location, facility and insurance type. These need to be addressed urgently since there are several effective and well-tolerated anti-MM treatments which can potentially benefit patients in case the initial socioeconomic, clinical and psychosocial barriers are overcome. Disclosures Chanan-Khan: Xencor: Research Funding; Pharmacyclics: Research Funding; Merck: Research Funding; Jansen: Research Funding; Mayo Clinic: Employment; Ascentage: Research Funding; Millennium: Research Funding; AbbVie: Research Funding. Ailawadhi:Pharmacyclics: Research Funding; Celgene: Consultancy; Amgen: Consultancy, Research Funding; Cellectar: Research Funding; Janssen: Consultancy, Research Funding; Takeda: Consultancy.

Background: Median age at diagnosis for MM is 69 years with approximately 33% of the newly diagnosed MM (NDMM) patients aged ≥80 years (elderly). Yet, outcomes data and clinical trial participation in elderly MM patients are limited due to frailty and frequent comorbidities. Moreover, elderly patients are not candidates for stem cell transplant (SCT) and age is an independent poor prognostic marker, leading to disparate outcomes. The present study evaluated trends in outcomes and predictors of survival among elderly NDMM patients in the United States (U.S.). Methods: Using Surveillance Epidemiology and End Results (SEER) database, we extracted data on age, gender, geographical regions, year of diagnosis, and vital status for elderly patients (age ≥ 80 years) with MM from 1975 to 2016. Relative survival (RS) was estimated as the ratio of observed survival to the survival expected in the general population in the absence of malignancy. This adjusted for the competing causes of mortality prevalent in elderly patients. Mortality rates were age-adjusted. To estimate trends in mortality, we estimated annual percentage change (APC) and average annual percentage change (AAPC) by fitting the data in the join point regression model using the NCI's Join point Regression Program, Version 4.5.0.1. A multivariate analysis was conducted to analyze the predictors of overall and myeloma-specific mortality among elderly patients fitting into Cox proportion hazard regression model. Results: A total of 17,265 elderly MM patients were eligible for the study. Majority were females (n=9,487, 55%), were non-Hispanic whites (NHW) (n=12,895, 74.7%) and were diagnosed in the Western region of the U.S. (n=8,541, 49.5%). The median age was 84 years (IQR 81-87). The median RS for the whole period (1975-2016) was 19.8 months with 1- and 5- year RS of 60.1% (95%CI: 58.8-61.3) and 20.9% (95%CI: 19.5-22.3) respectively. The median RS increased from 8.45 months in 1975 to 29.86 months in 2013. One and 5- year RS also increased from 42.7% (95%CI: 32.4-52.5) and 12.9% (95%CI: 5.8-22.7) in 1975 to a 1- and 5-year RS of 72.3% (95%CI: 65.4-78.1) and 31.1% (95%CI: 23.4-39.1) in 2013, respectively (Fig.1). However, the age standardized mortality rate for the whole period showed an increasing trend with an AAPC of 2.3 (0.5-4, P<0.001). On fitting joinpoint regression, 2 distinct joinpoints were identified, calendar years 1977 and 1989 (Fig 2). Most of the increase in mortality rate was noted in the period 1975-1989. Since 1989, the mortality rates have shown a decreasing trend which is marginal but statistically significant, with an APC of -0.41 (95%CI: -0.7- -0.1, p<0.001). On multivariate analysis, increasing age (p<0.001) and non-northeast location (p<0.01) were associated with higher overall and MM-specific mortality. Female gender was associated with lower overall mortality (p<0.001) but not myeloma-specific mortality. While "other" race/ethnicity (not NHW, non-Hispanic black; NHB or Hispanic) was associated with lower risk of overall and myeloma-specific mortality, NHB were associated with a lower MM-specific (p<0.001) but not overall mortality. Conclusions: Our results suggest that although RS has improved significantly in the elderly patients, the mortality rates have not changed drastically over the years. Besides, factors like advancement in diagnosis and treatment which have improved RS, early diagnosis (leading to lead time bias) may also be contributing. Furthermore, there are several gender-specific, geographic and racial/ethnic disparities in outcomes of elderly MM patients, which need to be assessed prospectively. Although, a small decline in mortality rates in the more recent time is promising, further studies are warranted on interventions including aggressive supportive care directed at elderly patients with MM, so that MM survivorship can be improved. There should be strong consideration to increaseenrollment of the elderly in prospective clinical trials so that evidence-based guidelines can be developed. Disclosures Manochakian: Takeda: Membership on an entity's Board of Directors or advisory committees; Guardant Health: Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Membership on an entity's Board of Directors or advisory committees; Novocure: Membership on an entity's Board of Directors or advisory committees. Chanan-Khan:Merck: Research Funding; Ascentage: Research Funding; Millennium: Research Funding; Jansen: Research Funding; Mayo Clinic: Employment; Pharmacyclics: Research Funding; AbbVie: Research Funding; Xencor: Research Funding. Ailawadhi:Janssen: Consultancy, Research Funding; Takeda: Consultancy; Celgene: Consultancy; Amgen: Consultancy, Research Funding; Cellectar: Research Funding; Pharmacyclics: Research Funding. Off Label Use: Do not remove- this information is relevant to Abstract ID 125629: TAK-169 is a dimeric fusion protein of an anti-CD38 antibody single chain variable fragment fused to a modified Shiga-like toxin-A subunit..

Multiple myeloma (MM) is a neoplasm thought to arise from a damaged germinal center B-cell that progresses to a plasma cell clone arising in bone marrow. MM comprises 20% of all hematologic cancer deaths. Persons of African ancestry (AA) have a 1.5 to 2-fold higher risk compared to individuals of European ancestry (EA). Genetically driven differences in hematopoiesis may lead to variation in the levels white blood cell (WBC) subsets which could, in turn, be associated with MM etiology. There are differences in genetic determinants of WBC traits between EA and AA populations, with possible implications for the racial disparity in risk. We tested the above hypothesis using Mendelian randomization (MR), an approach that leverages genetic determinants of specific traits (i.e. WBC counts) to estimate their effects on the risk of an outcome; and a transcriptome-wide association study (TWAS), which utilizes genetic predictors of gene expression to identify susceptibility genes. These analytic approaches were applied to data from the African American Multiple Myeloma Study (AAMMS) consisting of 1813 cases and 8871 AA cancer-free controls to examine how differences in heritable WBC gene expression profiles influence MM risk. Genetic determinants of variation in WBC subsets in AA were obtained from the literature and supplemented with new genome-wide association findings in AA subjects from the UK Biobank cohort (n=6108). Odds ratios (OR) for MM per 1 standard deviation (SD) increase in each WBC phenotype were estimated using independent (linkage disequilibrium (LD) r2<0.10) variants with P<10-6 as genetic instruments. Analyses based on variants associated with WBC traits in AA populations did not identify any statistically-significant associations between MM risk and WBC overall (p=0.81, using 15 SNPs) or subsets (lymphocytes, monocytes, eosinophils, neutrophils and basophils, p>0.05 for each). However, when we applied genetic determinants of WBC identified in 330,000 cancer-free EA UK Biobank participants (P<10-8, replication P<0.05, LD r2<0.05), a statistically significant inverse relationship emerged between increasing lymphocyte counts and MM risk (OR=0.80, 95% CI: 0.66-0.97, p=0.02, using 385 SNPs), as well as increasing basophil counts (OR=0.63, 95% CI: 0.41-0.96, p=0.03, using 140 SNPs). Next, we examined the association between WBC gene expression profiles and MM risk in AAMMS data. We applied published and validated ancestry-specific models developed using the PrediXcan approach, which leverage germline genetic and transcriptomic data from the Multi-Ethnic Study of Atherosclerosis (MESA) (Mogil et al. PMID: 30096133). The primary TWAS used gene expression models trained in AA subjects (n=233), with sensitivity analyses using models developed in AA and Hispanic subjects (n=585). The TWAS significance threshold was based on the number of genes with significant germline prediction models (p<0.05 and R2 ≥0.05) in AA, corresponding to P < 0.05/2700 = 1.85×10-5. The expression of two genes was significantly associated with MM risk: KANK1at 9p24.3 (P = 1.01×10-5) and DNAJC27at 2p23.3 (P = 1.56×10-5). KANK1is a candidate tumor suppressor gene for renal cell carcinoma and has recently been associated with MM risk in AA [Du, Blood 2017 130:3058]. Here we provide additional evidence for its role in MM etiology via gene expression-mediated mechanisms. DNAJC27 (previously known as RBJ) is a novel MM risk gene linked to constitutive activation of ERK in solid tumors. We also identified two suggestively associated genes: PRR14 (P = 1.34×10-4; combined AA-Hispanic sample: P = 1.56×10-6), which has been linked to MM risk in EA populations, and PARP16 (P = 9.46×10-5). To our knowledge this is the first study to comprehensively examine variation in WBC traits and gene expression profiles with respect to MM risk in AA. Our TWAS analysis leveraged data from the largest collection of genetic and gene expression data in AA, enabling ancestry-matched inference and identification of two novel risk genes. Although the limited availability of genetic instruments for WBC limited the power of MR analysis, findings using variants identified in European populations may offer some insight into trans-ethnic etiologic pathways and contribute to risk stratification strategies using genetic and blood cell count biomarkers. Future studies, particularly with MGUS-free controls, are needed to validate these results. Disclosures Song: Millennium Pharmaceuticals Inc: Employment. Rand:Ancestry.com: Employment. Ailawadhi:Cellectar: Research Funding; Janssen: Consultancy, Research Funding; Celgene: Consultancy; Pharmacyclics: Research Funding; Amgen: Consultancy, Research Funding; Takeda: Consultancy. Nooka:Takeda: Honoraria, Other: advisory board participation; Janssen: Honoraria, Other: advisory board participation; GSK: Honoraria, Other: advisory board participation; Spectrum pharmaceuticals: Honoraria, Other: advisory board participation; Adaptive technologies: Honoraria, Other: advisory board participation; Amgen: Honoraria, Other: advisory board participation; Celgene: Honoraria, Other: advisory board participation; BMS: Honoraria, Other: advisory board participation. Singhal:Bureau of Millennium/Takeda, Celgene, Janssen, Celgene, Bristol-Myers Squibb and Bluebird: Speakers Bureau. van Rhee:Takeda: Consultancy; Sanofi Genzyme: Consultancy; Castleman Disease Collaborative Network: Consultancy; EUSA: Consultancy; Adicet Bio: Consultancy; Kite Pharma: Consultancy; Karyopharm Therapeutics: Consultancy. Mehta:Millennium/Takeda, Celgene; stock in Celgene, Bristol-Myers Squibb and Bluebird: Speakers Bureau. Wolf:Takeda: Consultancy; Celgene: Consultancy; Novartis: Consultancy; Janssen: Consultancy; Amgen: Consultancy. Martin:Roche and Juno: Consultancy; Amgen, Sanofi, Seattle Genetics: Research Funding. Fiala:Incyte: Research Funding. Terebelo:Jannsen: Speakers Bureau; Celgene: Honoraria; Newland Medical Asociates: Employment. Anderson:Bristol-Myers Squibb: Other: Scientific Founder; Oncopep: Other: Scientific Founder; Amgen: Consultancy, Speakers Bureau; Janssen: Consultancy, Speakers Bureau; Takeda: Consultancy, Speakers Bureau; Celgene: Consultancy, Speakers Bureau; Sanofi-Aventis: Other: Advisory Board. Vij:Bristol-Myers Squibb: Honoraria, Research Funding; Celgene: Honoraria, Research Funding; Genentech: Honoraria; Janssen: Honoraria; Karyopharm: Honoraria; Sanofi: Honoraria; Takeda: Honoraria, Research Funding. Bernal-Mizrachi:TAKEDA: Research Funding; Kodikas Therapeutic Solutions, Inc: Equity Ownership; Winship Cancer Institute: Employment, Patents & Royalties. Morgan:Amgen, Roche, Abbvie, Takeda, Celgene, Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Other: research grant, Research Funding. Zonder:Celgene Corporation: Consultancy, Honoraria, 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; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees; Intellia: Consultancy, Membership on an entity's Board of Directors or advisory committees; Caelum: Consultancy, Membership on an entity's Board of Directors or advisory committees; Alnylam: Consultancy, Membership on an entity's Board of Directors or advisory committees; BMS: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees; Oncopeptides: Consultancy, Membership on an entity's Board of Directors or advisory committees. Huff:Member of Safety Monitoring Board for Johnson and Johnson: Membership on an entity's Board of Directors or advisory committees; Karyopharm, Sanofi, MiDiagnostics: Consultancy. Lonial:Karyopharm: Consultancy; Takeda: Consultancy, Research Funding; Amgen: Consultancy; BMS: Consultancy; Janssen: Consultancy, Research Funding; GSK: Consultancy; Celgene Corporation: Consultancy, Research Funding; Genentech: Consultancy. Orlowski:Poseida Therapeutics, Inc.: Research Funding.

Background Multiple myeloma (MM), a malignant neoplasm of plasma cells in the bone marrow, accounts for up to 1.8% of all cancers in the U.S., most frequently affecting people 65-74 years old. A variety of therapies are available to manage MM, including stem cell transplantation (SCT), immunomodulatory drugs (IMiD), proteasome inhibitors (PI), monoclonal antibodies (mAB), and alkylating agents (alk). Given the heterogeneity of MM and the rapidly evolving therapeutic landscape, MM contemporaneous real-world treatment patterns are not well described. We examined the patient characteristics and first-line (LT1) treatment patterns in NDMM patients. Methods MM patients (≥18 years), diagnosed in April 30, 2015 - April 29, 2017 (early cohort) or in April 30, 2017 - April 30, 2019 (recent cohort), were followed retrospectively from MM diagnosis to last patient activity in the Flatiron Health database - a geographically-diverse, longitudinal electronic health record spanning over 280 community and academic cancer clinics in the U.S. LT1 regimens were described as: 1) containing an IMiD (thalidomide, lenalidomide [R], or pomalidomide), PI (bortezomib [V], carfilzomib, or ixazomib), alk (melphalan, cyclophosphamide [C], bendamustine), mAB (daratumumab, elotuzumab), or combinations of these; and 2) doublet/monotherapy (doublets-) vs. triplet or greater agent (triplets+) combinations. Treatment patterns were examined by SCT status and by cytogenetic risk (high: del17p, t(4;14) and/or t(14;16); standard: ≥1 cytogenetic tests without high cytogenetic risk) and age groups (<65, 65-74, ≥75). Duration of therapy (DOT) and time to next therapy (TTNT) were estimated using Kaplan-Meier methods in the early cohort with longer follow-up. Results Of 4,070 NDMM patients, 3,433 were non-SCT (nSCT: early cohort: n=1,736; recent cohort: n=1,697) and 637 had SCT (early cohort: n=407; recent cohort: n=230). In nSCT patients, mean age at diagnosis was 70 years (SD: 10); 46% were female; 36% had stage III (699/1916, among non-missing), and 15% (392/2574, among non-missing) had high risk MM (25% had unknown cytogenetics). SCT patients were younger at diagnosis (mean [SD]: 61 years [9]); 44% were female; 25% (117/470, in non-missing) had stage III, and 19% (102/547, in non-missing) had high risk MM (14% had unknown cytogenetics). Overall, proportions with known cytogenetic risk were similar within SCT status cohorts over time but were lower in the SCT group (nSCT early vs. recent cohort: 26% vs. 24% had unknown cytogenetics; and in SCT: 15% vs. 13%, respectively). In nSCT and SCT patients, respectively, most common regimens were VRd (d: dexamethasone; 44% and 58%), Rd (16% and 7%), Vd (13% and 1%), and VCd (12% and 4%). In nSCT patients, the use of VRd increased over time (37% [early cohort] to 51% [recent cohort]), while frontline therapy with Rd/Vd doublets (19% to 14%/16% to 9%) and with VCd (13% to 11%) decreased. In the nSCT recent cohort, VRd (51%) frontline therapy dominated, with a slightly higher proportion of patients in the high-risk group vs. standard and unknown risk receiving VRd (56% vs. 53% and 46%); use of doublet therapy with Rd/Vd was lower in the high risk (12%/5%) vs. standard risk group (14%/9%). Irrespective of age, VRd was the most common frontline regimen in the nSCT recent cohort, albeit its use was lower among patients 75+ years of age (43%) vs. younger patients (54% [<65 years] and 59% [65-74 years]); 75+ year old patients had a higher use of Rd/Vd doublets (19%/15%) vs. <65 (10%/5%) or 65-74 (10%/6%) years of age. Triplets+ were more commonly used than doublets- across all cohorts: 59% vs. 41% (nSCT early cohort); 74% vs. 26% (nSCT recent cohort); and 89% vs. 11% (SCT early cohort); 95% vs. 5% (SCT recent cohort). mAB use in the recent cohort was low: 1.4% nSCT and 2.2% SCT patients. In the nSCT early cohort, the median (95% CI) LT1 DOT was 10 months (9-11) and for TTNT was 14 months (13-16). Conclusions PI/IMiD treatment combinations were most commonly observed in both nSCT and SCT patients, with an increase in use from early (40%) to recent (56%) cohort in nSCT patients. Use of triplets, generally, is on the rise from early (60%) to recent cohorts (74%). LT1 TTNT was lower than has been shown in clinical trials. These findings indicate a notable change in treatment patterns over time in nSCT NDMM patients, highlighting the changing landscape of MM management. Disclosures Ailawadhi: Celgene: Consultancy; Takeda: Consultancy; Cellectar: Research Funding; Amgen: Consultancy, Research Funding; Janssen: Consultancy, Research Funding; Pharmacyclics: Research Funding. Romanus:Takeda: Employment. Cherepanov:Takeda: Employment. Yin:Takeda: Employment. Cheng:Takeda: Employment. Hari:Celgene: Consultancy, Honoraria, Research Funding; Takeda: Consultancy, Honoraria, Research Funding; BMS: Consultancy, Research Funding; Janssen: Consultancy, Honoraria; Kite: Consultancy, Honoraria; Amgen: Research Funding; Spectrum: Consultancy, Research Funding; Sanofi: Honoraria, Research Funding; Cell Vault: Equity Ownership; AbbVie: Consultancy, Honoraria.

Background: The development of novel treatment strategies has extended the median survival of MM to nearly a decade but the disease remains incurable and relapse is inevitable. The Bcl-2 pathway is highly relevant to MM cell survival and can be mitigated therapeutically. AT-101 is a novel, orally available pan Bcl-2 inhibitor (Bcl-2, Bcl-xl, Mcl-1, and Bcl-w). Preclinical in vitro and in vivo studies showed that AT-101 enhanced cytotoxicity of lenalidomide-dexamethasone (Rd). We conducted a phase I study in RRMM patients to establish the effective dose of AT-101 with Ld as well as record safety and preliminary efficacy of this combination (NCT02697344). Methods: Key eligibility criteria included: RRMM with measurable disease (serum monoclonal protein ≥1.0 g/dL or urine monoclonal protein >200mg/24 hour or serum immunoglobulin free light chain >10mg/dL AND abnormal serum free light chain ratio). Patients must have received 1-3 prior treatment regimens and have an absolute neutrophil count ≥1.0 x 109, platelets 75 x 109, creatinine clearance ≥50 mL/min, and ECOG performance status ≤2. AT-101 dosing was designed to reach a maximum daily target of 20mg (Cohort 1; 10 mg PO QD, Cohort 2; 20 mg PO QD) utilizing a standard 3 +3 dose escalation design in combination with standard doses of Rd. Treatment was given as outpatient for a maximum of 12, 28-day cycles. For pharmacodynamic studies, AT-101 alone was given in cycle 1, with R (25 mg on days 1-21) and d (40 mg weekly) added cycle 2 onwards. Results: Enrolled patients (n=10) included 60% males with median age 68.5 years (range 55-75) and median time since MM diagnosis 4.5 years (range 0.6-8.3). MM ISS stage was II/III in 7 patients and 8/10 had high-risk cytogenetics with 4 each having del17p and 1q+. Only 1 patient had t(11;14).Patients had received median 2 prior lines of therapy (range 1-3), with 7 having had prior autologous stem cell transplant (ASCT) and the initial induction regimen being bortezomib (V), R and dexamethasone (d) (VRd) in 8, Rd in 1 and cyclophosphamide (C) with Vd (VCd) in 1 patient. At the time of study entry, 3 patients were R refractory while 2 were refractory to both, V and daratumumab (Dara). Median duration of treatment was 7.5 cycles (range 2-12) and 3 patients completed all planned 12 cycles of treatment. Among the evaluable patients, dose limiting toxicities (DLTs) at 20 mg daily dose of AT-101 with 25 mg of R and 40 mg weekly included one patient with grade 4 febrile neutropenia and grade 4 neutropenia lasting 9 days and one patient with grade 4 thrombocytopenia lasting 8 days. G3/4 adverse events (AEs) included atrial flutter (n=1), white blood cell count decrease (n=3), neutropenia (n=5), febrile neutropenia (n=1) and thrombocytopenia (n=2), and back pain (n=1) . No G3/4 non-hematological AEs were noted. Any grade non-hematologic AEs seen in at least 20% (n=2) patients included fatigue (n=9), neuropathy (n=6), nausea (n=3), diarrhea (n=5), constipation (n=3), and creatinine increased (n=2). No patients experienced tumor lysis syndrome. Overall response rate (ORR) was 44% (2 each with very good partial response, VGPR and PR) and clinical benefit rate (CBR) was 89% with 2 additional patients showing minor response (MR) and 2 experiencing stable disease (SD) (Fig 1). Patients with high-risk disease had an ORR of 43% and a CBR of 100%. Median progression-free survival (PFS) for all patients was 8.1 months. Correlative analysis from patients who showed an objective response to treatment revealed a significant increase in bone marrow Th-effector cells, NK cells and cytotoxic CD8+ T-cells along with a significant decrease in immunosuppressive T-regulatory and B-regulatory cells was noted after 1 complete cycle of the combination therapy (p<0.05, Fig 2). Conclusions: This is the first reported clinical trial combining a Bcl-2 inhibitor with immunomodulatory drugs (IMiDs) in MM. AT-101-Rd is a clinically active regimen with an ORR of 40% in predominantly high-risk RRMM patients with an acceptable toxicity profile. Additional patients with MM experienced clinical benefit despite refractory status to prior therapy in this early phase clinical trial. These early findings support the further investigation of AT-101 specifically, and Bcl-2 inhibitors in general, with IMiDs in patients with MM. Disclosures Ailawadhi: Celgene: Consultancy; Amgen: Consultancy, Research Funding; Pharmacyclics: Research Funding; Cellectar: Research Funding; Janssen: Consultancy, Research Funding; Takeda: Consultancy. Chanan-Khan:Xencor: Research Funding; Pharmacyclics: Research Funding; Merck: Research Funding; Jansen: Research Funding; Mayo Clinic: Employment; Ascentage: Research Funding; Millennium: Research Funding; AbbVie: Research Funding. OffLabel Disclosure: AT-101 is not currently FDA-approved for treatment of any condition.

Background: The 2018 iwCLL guidelines recommend close observation of early stage CLL pts who do not meet indications for therapy ("watch and wait" strategy). Prior attempts at early therapeutic intervention in unselected early-stage CLL pts using alkylating agents such as chlorambucil and chemoimmunotherapy failed to show a significant benefit; and these therapies were associated with substantial toxicities. The introduction of Bruton tyrosine kinase (BTK) inhibitors has revolutionized the treatment landscape of CLL. The German CLL Study group recently presented results of the CLL12 study which demonstrated a significant improvement in event-free survival (EFS) among untreated early stage high risk CLL pts who received ibrutinib compared to placebo (median EFS not reached vs. 47.8 months, respectively; Langerbeins, EHA, 2019). Acalabrutinib is a more selective second-generation BTK inhibitor that has fewer adverse events in pts with CLL, and has shown equally impressive clinical activity for CLL pts. We are conducting an investigator initiated randomized phase 2 study to compare acalabrutinib with or without obinutuzumab (a glycoengineered anti-CD20 monoclonal antibody approved in the treatment of CLL) among high risk early stage CLL pts. Study Design: All pts with newly diagnosed (<2 years from registration) previously untreated early stage CLL who do not meet the 2018 iwCLL guidelines for initiation of therapy are eligible for enrollment in this study. Pts undergo risk stratification according to the CLL-International prognostic index (CLL-IPI) which consists of the following 5 variables: age >65 years (1 point), Rai stage I-IV (1 point), del17p and/or TP53 mutation (4 points), unmutated immunoglobulin heavy chain (IGHV) genes (2 points), and serum β2-microglobulin >3.5 g/dL (2 points). Pts with high (4-6) and very high (7-10) risk CLL-IPI are randomly (1:1) assigned to acalabrutinib 100 mg orally twice daily (Arm A) or acalabrutinib with obinutuzumab at a standard approved schedule (Arm B). Treatment with acalabrutinib is continued for a minimum of 2 years unless the patient has unacceptable side effects or withdraws consent. Pts with low (0-1) and intermediate (2-3) risk CLL-IPI score are assigned to an observation arm with follow-up once every 6 months for 2 years, and then according to routine clinical practice (Arm C). Endpoints: The primary endpoint of the intervention arms (Arms A and B) is the achievement of minimal residual disease (MRD)-negative complete remission in the bone marrow after 2 years of therapy. MRD is assessed using an 8-color flow cytometry with a detection limit of 0.01%. The primary endpoint of the observation arm (Arm C) is time to first therapy. Secondary endpoints for all arms are: progression-free survival, overall survival, and safety. Statistical design: A randomized trial comparing the experimental arm (acalabrutinib plus obinutuzumab) against the control arm (acalabrutinib alone) will be conducted as described by Rubinstein. A sample size of 36 pts per arm provides 80% power to detect an improvement in MRD-negative complete response rate from 10% to 30%, using a one-sided test at a significance level of 0.10 (EAST 6.4). We anticipate accruing an additional 8 high/very high risk pts (4 in each arm) to account for ineligibility, cancellation, or major treatment violation. The total enrollment for Arms A and B will be 80 pts. We will enroll 40 pts to Arm C; for a total enrollment of 120 pts. Key correlatives: Comprehensive profiling to assess the innate and adaptive immune system in paired peripheral blood and bone marrow will be conducted in all pts registered to Arms A and B at baseline, 12 and 24 months after enrollment. In addition, bone marrow hematopoietic function will be assessed in all pts at these time points. We will employ a CLL focused custom 61-gene panel to estimate tumor mutational burden as well as mutational profiles for each patient at baseline, 12, and 24 month time points, as well at the time of disease progression. Preliminary results: The trial is registered at clinicaltrials.gov NCT03516617. The trial opened to accrual at all three Mayo Clinic sites (Rochester, MN; Jacksonville, FL; and Scottsdale, AZ) in September 2018. Twenty-eight pts have been registered; the baseline characteristics are shown in Table 1. The trial is expected to complete enrollment in September 2020; and the primary analysis will be available in September 2022. Disclosures Parikh: Janssen: Research Funding; AstraZeneca: Honoraria, Research Funding; Pharmacyclics: Honoraria, Research Funding; MorphoSys: Research Funding; AbbVie: Honoraria, Research Funding; Acerta Pharma: Research Funding; Ascentage Pharma: Research Funding; Genentech: Honoraria. Ding:DTRM Biopharma: Research Funding; Merck: Research Funding. Ailawadhi:Pharmacyclics: Research Funding; Cellectar: Research Funding; Takeda: Consultancy; Amgen: Consultancy, Research Funding; Janssen: Consultancy, Research Funding; Celgene: Consultancy. Kenderian:Novartis: Patents & Royalties, Research Funding; Tolero: Research Funding; Humanigen: Other: Scientific advisory board , Patents & Royalties, Research Funding; Lentigen: Research Funding; Morphosys: Research Funding; Kite/Gilead: Research Funding. Chanan-Khan:Mayo Clinic: Employment; Ascentage: Research Funding; Millennium: Research Funding; Jansen: Research Funding; AbbVie: Research Funding; Xencor: Research Funding; Pharmacyclics: Research Funding; Merck: Research Funding. Kay:Infinity Pharmaceuticals: Other: DSMB; Celgene: Other: Data Safety Monitoring Board; Agios: Other: DSMB; MorphoSys: Other: Data Safety Monitoring Board. OffLabel Disclosure: Drug: Acalabrutinib Purpose: treatment of CLL

Background: MM clinical trials often have stringent eligibility criteria that limit the enrollment of patients (pts) reflective of the general patient population (Shah, Clin Lymphoma Myeloma Leuk 2017). The Connect® MM Registry, a prospective observational study of pts with newly diagnosed MM (NDMM) in the US, provided the opportunity to examine differences between pts with MM who were identified as RCT-eligible vs -ineligible, to observe the generalizability of clinical trial results to real-world clinical settings. Differences in baseline characteristics, treatment, clinical outcomes, and HRQoL were examined in RCT-eligible and -ineligible pts from this registry, which represents an unselected, broad real-world population. Methods: Pts with NDMM were enrolled at 250 community, academic, and government sites. Eligible pts were ≥18 y of age with symptomatic MM diagnosed ≤2 months preenrollment per the International Myeloma Working Group (IMWG) criteria. For this analysis, pts were considered ineligible for RCT per the following key exclusion criteria previously described: absolute neutrophil count ≤1.5 × 109/L, platelet count ≤75 × 109/L, creatinine >2.5 mg/dL, AST/ALT >3 times the ULN, peripheral neuropathy grade >2; ECOG PS 3/4; history of myelodysplastic syndromes/other hematologic malignancies, or solid tumors (Shah 2017). Sites administered pt HRQoL questionnaires and provided clinical data at baseline and quarterly during follow-up until death or study discontinuation. Differences in HRQoL at baseline, changes from baseline to 1 and 2 years, and survival outcomes, adjusted for covariates via propensity score, were compared between RCT-eligible/-ineligible pts. Results: Of the 3011 pts enrolled, 2873 pts met the CRAB (hyperCalcemia, Renal failure, Anemia, and Bone disease) criteria per IMWG at enrollment. Of these, 1622 (56.5%) were identified as RCT-eligible and 1251 (43.5%) as RCT-ineligible (data cut-off February 7, 2019). Both groups were similar in median age, sex, race, and ethnicity distribution, although the RCT-ineligible group had more pts aged ≥75 y (26.3% vs 23.2%) and more pts with ECOG PS 3/4 (6.2% vs none). Overall, 34.5% of RCT-ineligible pts received a transplant vs 42.8% of RCT-eligible pts. More RCT-ineligible pts had ISS stage III disease (39.4% vs 19.8%), elevated calcium (≥11.5 mg/dL; 12.7% vs 6.8%), elevated creatinine (>2.0 mg/dL; 40.3% vs 6.5%), and low hemoglobin (<10 g/dL or >2 g/dL <LLN; 60.8% vs 40.3%). Use of triplet treatment (54.2% vs 56.2%) and alkylator (24.9% vs 20.1%) was similar between the RCT-ineligible/-eligible groups. Lenalidomide + bortezomib + dexamethasone (RVd) was the most common initial therapy, and R was the most common maintenance therapy in both groups, but fewer RCT-ineligible pts received RVd as initial therapy (23.9% vs 31.0%) and R as first maintenance regimen (18.1% vs 22.7%). Absolute baseline HRQoL scores were significantly higher, indicating better HRQoL, in RCT-eligible (115.9) vs -ineligible (111.5) pts on the Functional Assessment of Cancer Therapy-Multiple Myeloma (FACT-MM) Total score (P=0.007), FACT-MM Trial Outcome Index (74.3 vs 70.3, P=0.002), and FACT-MM Subscale (37.3 vs 35.5, P=0.003). Scores were similar for EuroQol-5D Overall Index (0.73 vs 0.72, P=0.5) and Brief Pain Inventory (3.42 vs 3.43, P=0.9). Both RCT-eligible and -ineligible pts showed significant improvement in HRQoL from baseline at years 1 and 2, although the magnitude of improvement was similar between both groups (Fig. 1a and b). RCT-ineligible pts showed significantly shorter median PFS and OS vs RCT-eligible pts (Fig. 2 & 3, respectively). Conclusions: The CONNECT MM registry provided the opportunity to examine key differences between RCT-eligible and -ineligible pts. By applying common RCT eligibility criteria, a substantial proportion of MM pts (43.5%) in this real-world population may have been ineligible to participate in a RCT. RCT-ineligible pts had advanced disease, poor performance status, and poor laboratory parameters at baseline vs RCT-eligible pts, which could affect PFS and OS. These findings enhance our understanding of HRQoL among MM pts, which at present, is largely based on RCT participants. A similar magnitude of HRQoL improvement in both groups at 1 and 2 years suggests the need to evaluate RCT eligibility criteria in MM to help broaden enrollment and maximize external validity. Disclosures Wagner: Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; American Cancer Society: Other: Section editor, Cancer journal. Toomey:Celgene: Consultancy. Ailawadhi:Takeda: Consultancy; Amgen: Consultancy, Research Funding; Celgene: Consultancy; Cellectar: Research Funding; Janssen: Consultancy, Research Funding; Pharmacyclics: Research Funding. Jagannath:Merck & Co.: Consultancy; Bristol-Myers Squibb: Consultancy; AbbVie: Consultancy; Celgene Corporation: Consultancy; Janssen Pharmaceuticals: Consultancy; Karyopharm Therapeutics: Consultancy. Gasparetto:Janssen: Consultancy, Honoraria, Other: Travel, accommodations, or other expenses paid or reimbursed ; BMS: Consultancy, Honoraria, Other: Travel, accommodations, or other expenses paid or reimbursed ; Celgene: Consultancy, Honoraria, Other: Travel, accommodations, or other expenses paid or reimbursed . Durie:Amgen, Celgene, Johnson & Johnson, and Takeda: Consultancy. Narang:Celgene: Speakers Bureau. Rifkin:Amgen: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees. Terebelo:Celgene: Honoraria; Jannsen: Speakers Bureau; Newland Medical Asociates: Employment. Omel:Celgene, Takeda, Janssen: Other: Patient Advisory Committees. Hardin:Celgene: Membership on an entity's Board of Directors or advisory committees. Lee:Janssen: Consultancy, Research Funding; Takeda: Consultancy, Research Funding; Daiichi Sankyo: Research Funding; Celgene: Consultancy, Research Funding; Sanofi: Consultancy; GlaxoSmithKline plc: Research Funding; Amgen: Consultancy, Research Funding. Srinivasan:Celgene: Employment, Equity Ownership. Liu:TechData: Consultancy. Dhalla:Celgene: Employment. Catamero:Celgene: Employment, Equity Ownership. Abonour:BMS: Consultancy; Takeda: Consultancy, Research Funding; Janssen: Consultancy, Research Funding; Celgene: Consultancy, Research Funding.

BACKGROUND: Proteasome inhibitors (PIs) combined with an Rd backbone constitute commonly used regimens in RRMM in the US. Lack of data from head-to-head clinical trials comparing the efficacy of these PI-Rd triplets and the extent to which efficacy translates to benefit in routine care highlight the need for real-world evidence. We conducted a comparative effectiveness analysis of time to next therapy (TTNT) of these PI-Rd triplet combinations in a real-world representative cohort of RRMM patients. METHODS: In this retrospective cohort study, RRMM patients who initiated an index regimen with IRd, KRd, or VRd in ≥2nd line of therapy (LOT 2+) were followed between 1/2014-9/2018 in Optum's deidentified national electronic health records database. This database captures information on all patients treated by >140,000 providers across 50 states in the US. It is representative of the US general population. Baseline data included: a modified frailty score utilizing age and Charlson Comorbidity Index1, ECOG performance status, CRAB symptoms, ISS stage, cytogenetic risk (high: del[17p], t[4;14], or t[14;16]), history of: cardiovascular disease, peripheral neuropathy, stem-cell transplant, and uncontrolled hypertension, prior PI and/or IMID exposure and refractory status, time from diagnosis to start of index LOT, time from start of frontline therapy to start of LOT 2, and treatment-free interval prior to index LOT. Duration of therapy (DOT) and TTNT were estimated using Kaplan-Meier methods and compared using stratified (by LOT) ± baseline-adjusted Cox proportional hazard models with a repeated measures analysis of pt-LOTs with robust sandwich estimators to account for inclusion of patients in multiple LOTs. The main analysis was repeated in subgroups a priori defined by frailty score, cytogenetic risk, prior PI and/or IMID exposure and LOT. Observations were censored at time of loss to follow up/end of study period (9/30/2018). RESULTS: Overall, 650 patients with 733 pt-LOTs (IRd, n=168; KRd, n=208; VRd, n=357) were included; 20% of the RRMM patients in this cohort were treated at academic centers. In the I-/K-/V-Rd groups, respectively, median age was 71/65/71 years and 42/22/38% patients were ≥75 years old; 39/55/46% and 28/14/29% patients had a modified frailty score of intermediate and frail, respectively; 71/88/80% had a symptomatic relapse with at least 1 CRAB symptom; 20/28/13% patients had high cytogenetic risk; 69/72/90% patients were treated in 2-3 LOT, and 63/70/32% patients had prior exposure to a PI+IMID (P<0.05 for all). The median follow-up was 14.4 months. Unadjusted median DOT of index LOT was 12.3/7.2/10.0 months, with a lower risk of discontinuation of the oral PI component for I in comparison to both K and V (HR[I vs K] of 0.66 and HR[I vs V] of 0.68) and R component in the IRd vs KRd and VRd groups (HR[I vs K] of 0.64 and HR[I vs V] of 0.75) (P<0.05 for all). Unadjusted median TTNT was 12.7/8.6/14.2 months for I-/K-/V-Rd in LOT ≥2; with HR for TTNT of 0.76 (IRd vs KRd; P<0.05); 1.01 (IRd vs VRd; P=0.96); 1.33 (KRd vs VRd; P<0.05). The adjusted HRs for TTNT I-/K-/V-Rd in LOT ≥2 were 0.82 (IRd vs KRd); 0.93 (IRd vs VRd); 1.13 (KRd vs VRd; P>0.05 for all), and were comparable between all 3 groups. A significant TTNT benefit for IRd vs KRd was observed among patients with high cytogenetic risk (HR: 0.47) and with intermediate frailtymodified score (HR: 0.60; P<0.05 for all). CONCLUSIONS: In this real-world representative RRMM cohort, in unadjusted analyses, the IRd group had a longer DOT of the PI and R components and a longer TTNT in comparison with KRd. After adjusting for baseline confounders to separate the treatment effect, the I/K/V-Rd triplet combinations were comparable in TTNT, but IRd was significantly better than KRd in patients with high-risk cytogenetics and with an intermediate frailty score. Residual confounding is always a potential limitation of any non-randomized study. Conversely, the results of randomized, clinical trials are limited in generalizability as 40-60% of patients are excluded due to inability to meet eligibility criteria. This is especially pertinent in an elderly RRMM population as demonstrated in the real-world effectiveness results in this study. Ref: 1. Palumbo, et al. Blood. 2015;125:2068-2074 Figure Disclosures Chari: 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; 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. Romanus:Takeda: Employment. Raju:Millennium Pharmaceuticals, Inc., a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Other: Xcenda received funding from Takeda to complete this analyses., Research Funding; Xcenda, LLC: Employment. Cain:Takeda: Employment. Blazer:Xcenda: Employment; Takeda: Other: Xcenda received funding from Takeda for completion of this analysis, Research Funding. Farrelly:Xcenda: Employment; Takeda: Other: Xcenda received funding from Takeda for completion of this analysis, Research Funding. Stull:Takeda: Employment. Ailawadhi:Pharmacyclics: Research Funding; Cellectar: Research Funding; Celgene: Consultancy; Takeda: Consultancy; Janssen: Consultancy, Research Funding; Amgen: Consultancy, Research Funding.

Background CD38 is highly expressed on MM cells, hence anti-CD38 agents are of interest as a therapeutic approach in MM. The anti-CD38 monoclonal antibody, dara, as mono- or combination therapy, has substantially improved efficacy outcomes in RRMM, including in heavily pretreated pts. However, many pts relapse and new therapeutic approaches are needed, particularly for pts R/R to dara. TAK-169 is a dimeric fusion protein of an anti-CD38 antibody single chain variable fragment fused to a modified Shiga-like toxin-A subunit. Its unique mechanism of action involves specific binding to CD38+ cells, forced internalization into the target cells, retrograde transport to the cytosol, and irreversible, enzymatic inactivation of target cell ribosomes to cause apoptosis. TAK-169 showed potent, rapid in vitro activity on CD38-expressing cell lines and in vivo efficacy in MM mouse xenograft tumor models with a wide CD38 expression range when administered intravenously (IV) once weekly (QW) or once every 2 weeks (Q2W). Activity was also shown in ex vivo assays from 6 pt bone marrow aspirate (BMA) samples, including from a dara-resistant pt (EC50 5 nM). TAK-169 retained in vitro activity in the presence of dara with modest shifts in EC50 noted at higher dara concentrations. In contrast to dara, TAK-169 has direct tumor cell kill activity that is independent of a pt's immune function status and may therefore be effective in a dara-resistant setting. Accordingly, this phase 1 study will assess safety, tolerability, preliminary efficacy, pharmacokinetics (PK) and pharmacodynamics (PD) of TAK-169 in RRMM. Methods This first-in-human, multicenter, open-label study (NCT04017130; Figure) comprises dose escalation (Part 1) and expansion (Part 2). Eligible pts must be aged ≥18 years with a confirmed diagnosis of MM. Pts enrolled in Part 1 should not be candidates for available therapies known to confer clinical benefit in RRMM. In part 2, pts enrolled should have received ≥3 prior lines of therapy, or ≥2 if one included a PI and IMiD combined. Prior anti-CD38 therapy (including dara) is permitted, except in the Part 2 anti-CD38 therapy-naive expansion cohort. In Part 1, the primary objective is to assess safety/tolerability of TAK-169 in pts with RRMM, and determine maximum tolerated dose/recommended Phase 2 dose (MTD/RP2D). Secondary objectives include efficacy, PK, PD and immunogenicity of TAK-169. Approximately 60 pts are planned to be enrolled to receive IV TAK-169 QW on Days 1/8/15/22 in 28-day cycles. Dosing will start at 50 μg/kg, with subsequent dose levels of 100, 200, 335, 500, 665 μg/kg. A 2nd Q2W dose escalation cohort may be initiated, starting at the QW MTD. The Bayesian Logistic Regression Model with overdose control will be used for dose escalation cohort 2 and for all subsequent dose escalation cohorts, and other non-DLT-safety, clinical, PK, and PD data will be considered. In Part 2, the primary objective is preliminary evaluation of TAK-169 clinical activity in RRMM. Secondary objectives include further evaluating safety, efficacy, PK, PD, and immunogenicity of TAK-169. Part 2 will enroll approximately 54 pts into dara RR (QW and Q2W dosing) and anti-CD38 therapy-naïve (QW dosing) cohorts. TAK-169 will be administered at the MTD/RP2D (QW and Q2W) determined in Part 1. Response will be monitored longitudinally using orthogonal approaches. M-protein levels in serum and urine will be measured each cycle to determine objective responses by International Myeloma Working Group (IMWG) criteria. Minimal residual disease status in pts suspected to be at complete response will be assessed. Circulating free DNA (cfDNA) will be collected from longitudinal plasma samples for disease monitoring. Baseline cytogenetic data will be collected, and TAK-169 efficacy will be assessed in pts with high-risk cytogenetics. Serial blood samples will be used to characterize PK and PD of TAK-169 after IV administration, and to assess the presence of antidrug antibodies. BMA samples collected at screening will be used to evaluate baseline expression of candidate biomarkers. Toxicity will be evaluated using National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE) version 5. Efficacy analyses will use descriptive statistics with a 95% confidence interval and the Kaplan-Meier method. PK parameters and immunogenicity status will be summarized using descriptive statistics. Recruitment is ongoing. Figure Disclosures Kumar: Celgene: Consultancy, Research Funding; Janssen: Consultancy, Research Funding; Takeda: Research Funding. Cornell:Takeda: Consultancy; KaryoPharm: Consultancy. Landgren:Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Merck: Other: IDMC; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Theradex: Other: IDMC; Adaptive: Honoraria, Membership on an entity's Board of Directors or advisory committees; Abbvie: 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; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Ailawadhi:Cellectar: Research Funding; Pharmacyclics: Research Funding; Janssen: Consultancy, Research Funding; Celgene: Consultancy; Amgen: Consultancy, Research Funding; Takeda: Consultancy. Higgins:Molecular Templates, Inc.: Employment, Equity Ownership. Willert:Molecular Templates: Employment. Waltzman:Molecular Templates, Inc.: Employment, Equity Ownership. Lin:Millennium Pharmaceuticals, Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment, Equity Ownership. Zhang:Millennium Pharmaceuticals, Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment. Lublinsky:Millennium Pharmaceuticals, Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment. Dash:Millennium Pharmaceuticals, Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment. Hanley:Millennium Pharmaceuticals, Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment. Manoharan:Millennium Pharmaceuticals, Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment. Leichter:Millennium Pharmaceuticals, Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment. Ottinger:Millennium Pharmaceuticals, Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment. Labotka:Millennium Pharmaceuticals, Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment. Newcomb:Millennium Pharmaceuticals, Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment, Equity Ownership. Vorog:Millennium Pharmaceuticals, Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment. OffLabel Disclosure: TAK-169 is a dimeric fusion protein of an anti-CD38 antibody single chain variable fragment fused to a modified Shiga-like toxin-A subunit

Background: Combinations of alkylating agents with proteasome inhibitors have demonstrated efficacy in newly diagnosed and relapsed multiple myeloma (MM), with melphalan or cyclophosphamide combinations being some of the commonly used regimens for initial treatment of MM. Ixazomib (Ixa) is an oral proteasome inhibitor that is approved for use in combination with lenalidomide for patients with relapsed MM. We examined if Ixa can be effectively combined with cyclophosphamide (Ctx) in order to develop a less expensive, all oral regimen for patients with relapsed MM. Patients and Methods: Patients with relapsed MM, who were proteasome inhibitor naïve OR have received less than 6 cycles of therapy with bortezomib and had a better than PR with no progression at the time of discontinuation, were enrolled. The primary objective was to determine overall response rate (ORR). Treatment consisted of Ixa 4mg PO days 1, 8, 15; Ctx 300 mg/m2 PO days 1, 8, 15, 22 and dexamethasone (Dex) 40 mg PO weekly in a 28-day cycle. Overall, 37 patients were accrued; data on 33 eligible patients were available for analysis as of July 18, 2019. Results: The median age was 71 (48-89), 61% were male and the median duration from diagnosis was 46 months (mos). Median number of prior lines of therapy was 4 (range 1-5), 76%, 42% and 67% respectively had a prior IMiD, proteasome inhibitor or stem cell transplant, respectively. At data cutoff, 22 (67%) had progressed, 4 (12%) had died and the median follow up of those alive was 21.3 mos. Fourteen patients are still receiving treatment, with median of 8.5 cycles. Most common reason for treatment discontinuation was disease progression (10 pts; 53%). The ORR was 60% including 6% CR and 24% VGPR. The median event free survival was 11.3 mos (95%CI: 9.0 - 26.8). Overall, 401 cycles have been administered across the study, with dose modifications/ hold required for Ixa, Ctx, and Dex in 9 (27%), 14 (42%), and 22 (67%) patients respectively, the most common reason being hematologic toxicity. A grade 3 or higher adverse event at least possibly attributed to the study drugs was seen in 77% of patients, hematologic in 67% and non-hematologic in 30%. (Table 1) The most commonly observed hematologic toxicities included thrombocytopenia, neutropenia, lymphopenia and anemia; for non-hematologic was nausea, diarrhea, peripheral neuropathy toxicity and fatigue. Conclusions: The combination of Ixa, Ctx and Dex (ICd) offers a convenient, all oral regimen for treatment of relapsed disease not refractory to proteasome inhibitors. The regimen has good efficacy in this group f heavily pretreated patients, with an acceptable toxicity profile. Disclosures Lacy: Celgene: Research Funding. Gertz:Ionis: Honoraria; Spectrum: Honoraria, Research Funding; Janssen: Honoraria; Celgene: Honoraria; Prothena: Honoraria; Alnylam: Honoraria. Ailawadhi:Takeda: Consultancy; Janssen: Consultancy, Research Funding; Cellectar: Research Funding; Pharmacyclics: Research Funding; Amgen: Consultancy, Research Funding; Celgene: Consultancy. Bergsagel:Janssen Pharmaceuticals: Consultancy; Celgene: Consultancy; Ionis Pharmaceuticals: Consultancy. Fonseca:AbbVie, Amgen, Bayer, Celgene, Kite, Janssen, Juno, Merck, Pharmacylics, Sanofi, Takeda: Other: Consultant/Advisor; Prognosticatin of MM based on Genetic Categorization by FISH: Patents & Royalties; Adaptive Biotechnologies: Other: Scientific Advisory Board. Dingli:alexion: Consultancy; Janssen: Consultancy; Millenium: Consultancy; Rigel: Consultancy; Karyopharm: Research Funding. Kapoor:Amgen: Research Funding; Takeda: Honoraria, Research Funding; Glaxo Smith Kline: Research Funding; Sanofi: Consultancy, Research Funding; Celgene: Honoraria; Cellectar: Consultancy; Janssen: Research Funding. Chanan-Khan:AbbVie: Research Funding; Pharmacyclics: Research Funding; Xencor: Research Funding; Merck: Research Funding; Jansen: Research Funding; Mayo Clinic: Employment; Ascentage: Research Funding; Millennium: Research Funding. Larsen:Janssen Oncology: Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees. Russell:Imanis: Equity Ownership. Stewart:Roche: Consultancy; Seattle Genetics: Consultancy; Takeda: Consultancy; Ionis: Consultancy; Janssen: Consultancy, Research Funding; Oncopeptides: Consultancy; Ono: Consultancy; Amgen: Consultancy, Research Funding; Bristol Myers-Squibb: Consultancy; Celgene: Consultancy, Research Funding. Kumar:Celgene: Consultancy, Research Funding; Janssen: Consultancy, Research Funding; Takeda: Research Funding.