Citations

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: 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.

Introduction : Daratumumab (DARA) is a human CD38 antibody approved in combination with standard-of-care (SoC) regimens in pts with NDMM who are TIE. DARA-based treatments showed significantly improved progression-free survival (PFS) in pts with TIE NDMM in ongoing phase 3 studies ALCYONE (DARA + bortezomib/melphalan/prednisone [D-VMP] vs VMP) and MAIA (DARA + lenalidomide/dexamethasone [D-Rd] vs Rd continuous). An NMA allows estimation of the relative efficacy of regimens not compared in head-to-head trials. A previous NMA examined D-VMP and D-Rd vs comparators (Facon T et al., EHA 2019), excluding the SWOG S0777 study (bortezomib/lenalidomide/dexamethasone [VRd]; Durie BG, et al. Lancet 2017) as it enrolled both transplant-eligible (TE) and TIE pts, and data for pts who are TIE only (~50% [aged ≥65 y and frail]) were unavailable. In this NMA, D-Rd and D-VMP had the highest probabilities of being more effective than reference treatment Rd continuous in terms of PFS. Recently, VRd received EMA approval for treatment of TIE NDMM based on SWOG S0777, but results specific to TIE pts are still unavailable. Recent NMAs of TIE pts (Blommestein HM et al., Haematologica, 2019; Weisel et al., EHA 2019; Cao Y et al., Clin Lymphoma Myeloma Leuk, 2019) have included data from the the intent-to-treat (ITT) population of SWOG S0777, though its inclusion violates the similarity assumption. Here, we present a sensitivity analysis of the previously-conducted NMA including all pts who received VRd in SWOG S0777 for a comprehensive view of the comparative effectiveness of DARA-based treatments in TIE NDMM. Methods: VRd was included as part of a sensitivity analysis of the previous NMA based on the ITT population, reporting PFS and overall survival (OS). The Guyot method was used to estimate OS hazard ratios (HRs) for pts aged ≥65 y (proxy for TIE) from SWOG S0777 (Durie BG et al., ASH 2018). Median follow-up in ALCYONE and MAIA was 27.8 months and 28.0 months, respectively. Based on a systematic literature review conducted through January 2019, both PFS and OS were extracted and synthesized in Bayesian NMAs. Choice of fixed- or random-effects (FE or RE) model was based on lowest deviance information criterion (DIC) and/or presence of heterogeneity in the network. Rd continuous was selected as reference, as it was commonly included in guidelines across regions. For PFS and OS, HR <1 indicates the comparison is not in favor of Rd continuous. In addition to the previous NMA, we also report an NMA sensitivity analysis including only comparators approved by the EMA that are relevant for the European, Middle East and/or Africa (EMEA) region (EMEA NMA). Results: Global NMA: RE model was used for both PFS and OS. Compared with Rd continuous, the PFS HR for VRd in the sensitivity analysis was 0.74 (95% credible interval [CrI], 0.42-1.30), which was similar to SWOG S0777 (0.71; [96% Wald confidence interval [CI], 0.56-0.91]) and higher than HRs for D-Rd (0.55; 95% CrI, 0.31-0.97) and D-VMP (0.58; 95% CrI, 0.20-1.62; Table). For OS, the SWOG S0777 HR estimated by Guyot algorithm for pts aged ≥65 y was 0.80 (95% CI, 0.56-1.16). Compared with Rd continuous, the OS HR for VRd in the sensitivity analysis was 0.80 (95% CrI, 0.51-1.26), which was similar to SWOG S0777 and higher than D-Rd (0.78; 95% CrI, 0.51-1.18). EMEA NMA: FE model was used for both PFS and OS. Compared with Rd continuous, the PFS HR for VRd in the sensitivity analysis was 0.74 (95% CrI, 0.60-0.92), which was higher than HRs of D-Rd (0.55; 95% CrI, 0.43-0.71) and D-VMP (0.64; 95% CrI, 0.41-1.02). Compared with Rd continuous, the OS HR for VRd in the sensitivity analysis was 0.80 (95% CrI, 0.55-1.17), which was higher than for D-Rd (0.78; 95% CrI, 0.56-1.09). These results are consistent with the Global NMA, but differ slightly as the EMEA NMA has fewer evidence-loops (only EMEA SoC regimens were included). Conclusions: This study demonstrated favorable efficacy outcomes for DARA-based regimens vs other relevant frontline options, such as VRd, for pts with NDMM who are TIE. Limitations of the sensitivity analysis include lack of comparative trial data and demographic differences between pts from SWOG S0777 and trials of frontline MM treatments for pts who are TIE included in our network. The majority of SWOG S0777 pts are TE (<65 y), who often have better prognoses than TIE pts (≥65 y), and thus violates the similarity assumption of NMAs. However, DARA-based regimens still showed a comparative clinical advantage. Disclosures Facon: Takeda: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; 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; Sanofi: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees. San-Miguel:Amgen, Bristol-Myers Squibb, Celgene, Janssen, MSD, Novartis, Roche, Sanofi, and Takeda: Consultancy, Honoraria. Usmani: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; Amgen, Celgene, Janssen, Sanofi, Takeda: Speakers Bureau. Dimopoulos:Sanofi Oncology: Research Funding. Kumar:Janssen: Consultancy, Research Funding; Takeda: Research Funding; Celgene: Consultancy, Research Funding. Mateos:Adaptive: Honoraria; EDO: Membership on an entity's Board of Directors or advisory committees; Pharmamar: Membership on an entity's Board of Directors or advisory committees; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; GSK: Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees. Cavo:Janssen, Celgene, Amgen, Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene, Janssen, Amgen, BMS, Abbvie, Takeda: Honoraria; Janssen, Celgene: Other: Travel Accommodations; Janssen, Celgene: Speakers Bureau. Heeg:Ingress-Health: Employment. Van Beekhuizen:Ingress-health: Consultancy. Pisini:Janssen: Employment, Equity Ownership. Nair:Janssen: Employment, Equity Ownership. Lam:Janssen: Employment, Equity Ownership. Slavcev:Janssen: Employment, Equity Ownership. He:Janssen: Employment, Equity Ownership.

Introduction: Daratumumab (DARA) is a human, CD38-targeted, IgG1κ monoclonal antibody approved as monotherapy in heavily pretreated relapsed/refractory multiple myeloma (RRMM) and in combination with standard-of-care regimens for transplant-ineligible NDMM and RRMM. The addition of DARA to standard-of-care regimens in phase 3 studies has consistently demonstrated a near doubling of complete response (CR) rates, tripling of minimal residual disease (MRD)-negativity rates, and reduction in the risk of disease progression or death by ≥44% in patients with transplant-ineligible NDMM or RRMM. In the primary analysis of the phase 3 MAIA study (median follow-up: 28.0 months), a significant progression-free survival (PFS) benefit (median not reached [NR] vs 31.9 months; hazard ratio [HR], 0.56; P<0.001) and a >3-fold increase in MRD-negativity rates (10-5 sensitivity threshold; 24.2% vs 7.3%; P<0.001) were observed for D-Rd vs Rd in patients with transplant-ineligible NDMM (Facon T, N Engl J Med 2019). Here, we report updated efficacy and safety findings from MAIA after 9 months of additional follow-up. Methods: Patients with NDMM ineligible for high-dose chemotherapy and autologous stem cell transplantation due to age ≥65 years or comorbidities were randomly assigned (1:1) to receive Rd ± DARA. Stratification factors included International Staging System stage (ISS [I vs II vs III]), region (North America vs other), and age (<75 vs ≥75 years). All patients received 28-day cycles of Rd (R: 25 mg orally once daily on Days 1-21; d: 40 mg orally on Days 1, 8, 15 and 22). In the D-Rd arm, DARA (16 mg/kg intravenously) was given weekly for Cycles 1-2, bi-weekly for Cycles 3-6, and every 4 weeks thereafter. Patients were treated until disease progression or unacceptable toxicity in both treatment arms. The primary endpoint was PFS. Key secondary endpoints included overall response rate (ORR), MRD-negativity rate (10-5 sensitivity, clonoSEQ® version 2.0), and safety. PFS on the next line of therapy (PFS2), defined as the time from randomization to progression on the next line of therapy or death, was also measured. Results: A total of 737 patients were randomized (D-Rd, N = 368; Rd, N = 369). Patient baseline characteristics were well balanced between the two treatment arms. Median (range) age was 73 (45-90) years, with 44% of patients ≥75 years of age. 27%, 43%, and 29% of all patients were ISS stage I, II, and III, respectively. Among 642 patients evaluable for FISH/karyotyping analysis, 86% had standard and 14% had high cytogenetic risk. After a median follow-up of 36.4 months, median PFS was NR with D-Rd vs 33.8 months with Rd (HR, 0.56; 95% confidence interval [CI], 0.44-0.71; P<0.0001; Figure). The estimated 36-month PFS rate was 68% with D-Rd vs 46% with Rd. The PFS benefit of D-Rd vs Rd was observed in all prespecified subgroups, except for patients with impaired hepatic function. Adding DARA to Rd continued to result in deeper responses with higher rates of ≥CR and ≥very good partial response (VGPR; Table). Median duration of response among responders was NR with D-Rd vs 40.7 months with Rd. Median PFS2 was NR vs 47.3 months with D-Rd vs Rd, respectively (HR, 0.69; 95% CI, 0.53-0.91; P=0.0079); follow up is ongoing. 143 (39%) vs 233 (64%) patients with D-Rd vs Rd, respectively, have discontinued treatment. 85 (23%) patients with D-Rd vs 103 (28%) patients with Rd have discontinued the study due to death. Grade 3/4 treatment-emergent adverse events (TEAEs; D-Rd/Rd) occurring in ≥10% of patients were neutropenia (51%/35%), lymphopenia (15%/11%), pneumonia (15%/9%), anemia (14%/21%), leukopenia (11%/6%), and hypokalemia (10%/10%); grade 3/4 infection rates were 36%/27%. The most common serious TEAE was pneumonia (14%/9%). 9% of patients in the D-Rd arm and 18% of patients in the Rd arm discontinued treatment due to TEAEs. The complete updated data set will be presented at the meeting with additional efficacy endpoints, including MRD-negativity rate. Conclusion: After longer follow up, the addition of DARA to Rd continues to demonstrate a significant PFS benefit and improved rates of deeper and more durable responses vs Rd alone in patients with transplant-ineligible NDMM. The longer follow-up also demonstrated a significant improvement in PFS2 favoring D-Rd, and no new safety concerns were observed. These results continue to support the use of D-Rd in the first line of treatment for transplant-ineligible patients with NDMM. Disclosures Bahlis: Janssen: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; Takeda: Consultancy, Honoraria; AbbVie: Consultancy, Honoraria; Celgene: Consultancy, Honoraria. Facon:Janssen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: 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; Sanofi: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees. Usmani:Amgen Array Biopharma, Bristol-Myers Squibb, Celgene, Janssen, Merck, Pharmacyclics, Sanofi, Takeda: Other: Research Grant; Amgen, Celgene, Janssen, Sanofi, Takeda: Speakers Bureau; Amgen, Bristol-Myers Squibb, Celgene, Janssen, Merck, SkylineDX, Takeda: Other: Consultant/Advisor. Kumar:Celgene: Consultancy, Research Funding; Janssen: Consultancy, Research Funding; Takeda: Research Funding. Plesner:Oncopeptides: Consultancy; Janssen: Consultancy, Research Funding; Takeda: Consultancy; AbbVie: Consultancy; Celgene: Consultancy; Genmab: Consultancy. Orlowski:Poseida Therapeutics, Inc.: Research Funding. Hulin:celgene: Consultancy, Honoraria; Janssen, AbbVie, Celgene, Amgen: Honoraria. Quach:Sanofi: Research Funding; Karyopharm: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees, Research Funding; GSK: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding. Goldschmidt:ArtTempi: Honoraria; John Hopkins University: Other: Grants and/or provision of Investigational Medicinal Product; BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Grants and/or provision of Investigational Medicinal Product, Research Funding; Novartis: Honoraria, Research Funding; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Grants and/or provision of Investigational Medicinal Product, Research Funding; Dietmar-Hopp-Foundation: Other: Grants and/or provision of Investigational Medicinal Product; Mundipharma: Research Funding; Adaptive Biotechnology: Membership on an entity's Board of Directors or advisory committees; MSD: Research Funding; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other, Research Funding; Amgen: Membership on an entity's Board of Directors or advisory committees, Other: Grants and/or provision of Investigational Medicinal Product, Research Funding; Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Grants and/or provision of Investigational Medicinal Product, Research Funding; Molecular Partners: Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees, Research Funding; Chugai: Honoraria, Other: Grants and/or provision of Investigational Medicinal Product, Research Funding. O'Dwyer:GlycoMimetics Inc: Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS: Research Funding; Onkimmune: Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Consultancy. Venner:Janssen: Honoraria; J&J: Research Funding; Amgen: Honoraria, Research Funding; Sanofi: Honoraria; Takeda: Honoraria; Celgene: Honoraria. Weisel:GSK: Honoraria; Takeda: Consultancy, Honoraria; Sanofi: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Honoraria, Research Funding; Juno: Consultancy; Celgene Corporation: Consultancy, Honoraria, Research Funding; Adaptive Biotech: Consultancy, Honoraria; Bristol-Myers Squibb: Consultancy, Honoraria; Amgen: Consultancy, Honoraria, Research Funding. Krevvata:Janssen: Employment. Pei:Janssen: Employment, Equity Ownership. Wang:Janssen: Employment. Van Rampelbergh:Janssen: Employment. Ukropec:Janssen: Employment, Equity Ownership. Uhlar:Janssen: Employment. Kobos:Janssen: Employment. Perrot:Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda: Honoraria; Amgen: Honoraria; Sanofi: Honoraria.

Abstract Introduction: Monoclonal antibodies (MoAbs) have shown activity in relapsed and refractory multiple myeloma (MM). Elotuzumab is an anti-SLAMF7 MoAb that synergizes with immunomodulatory agents (IMiDs) and is approved for treatment of relapsed and refractory MM. Anti-CD38 MoAbs (daratumumab, FDA approved and isatuximab, in clinical trials) have also entered the therapeutic MM landscape but little is known about how to best sequence MoAbs and the existence of cross resistance between different classes of MoAbs. We analyzed outcomes of patients who become refractory to elotuzumab with emphasis on the activity of anti-CD38 MoAbs in the post-elotuzumab setting. Methods: We identified patients from 14 academic institutions within the US who were refractory to elotuzumab administered alone or in combination with other agents. Patients were considered refractory to elotuzumab if treated with at least 4 weeks of therapy and had evidence of progressive disease (PD) within 60 days of last dose. Time zero (T0) was defined as point when myeloma became refractory to elotuzumab-containing regimen. Data were collected with an electronic platform and submitted to peer-based quality check for completeness and internal consistency. We analyzed demographics, characteristics of their myeloma and prior therapy including number and type of therapy prior to elotuzumab, duration of elotuzumab therapy, and outcome after becoming refractory to elotuzumab. We performed a multi-variable analysis of these factors to determine significant factors associated with survival post T0. We subsequently identified a subset of patients who received an anti-CD38 MoAb alone or in combination as next or subsequent line of therapy after T0 and report their outcomes. Results: Eighty-nine patients were evaluated. Eighty-six (96.6%) had progression on elotuzumab in combination with IMiD (N=82) or another agent (N=4). Median age at T0 was 65 years (range 28-90), 51% of patients were males, 65% were White, 54% had IgG subtype, 27% had ISS stage III at diagnosis, and 27% had high-risk cytogenetics. Patients received a median of 4 prior lines of treatment (range 1-11) prior to elotuzumab-containing regimen, including 66% who underwent autologous transplant. Sixty-one patients (69%) were refractory to at least one IMiD and one proteasome inhibitor (PI) at T0, classified as double-refractory. Twenty-one (23.6%) were quad-refractory, i.e. refractory to 2 IMiDs and 2 PIs. Twenty-eight patients (31.5%) were refractory to prior anti-CD38 MoAb. The median time from diagnosis to T0 was 59.5 months and duration of elotuzumab therapy was 3 months (range 0.4 - 59.5). Median OS from T0 for the entire cohort was 15.1 months (95% C.I. 9.3-20.9). In multivariate analysis, the only factors affecting OS after T0 were high-risk cytogenetics (HR 3.31, 95% C.I. 1.74-6.27, P<0.001) and refractoriness to prior anti-CD38 MoAb (HR 4.22, 95% C.I. 2.22-8.01, P<0.001). Interestingly, median OS for patients not refractory to anti-CD38 MoAb was 33.1 months vs. 4.5 months for anti-CD38 MoAb-refractory patients (Figure 1). After T0, 45 patients (50.6%) received an anti-CD38 MoAb in the next (N=28, 62.5%) or subsequent regimens (N=17, 37.8%). Median time between T0 and initiation of anti-CD38 MoAb was 1.2 months (0-15.0). Anti-CD38 MoAbs employed were: isatuximab in 4 (8.9%) and daratumumab in 41 patients (91.1%). In most cases, the anti-CD38 MoAb was administered in combination with IMiD (N=30, 66.6%) or bortezomib (N=7, 15.6%). The overall response rate (ORR) for anti-CD38 MoAb regimens was 35.6%; responses to specific combinations are outlined in the Table. Median PFS for elotuzumab-refractory patients receiving therapy with anti-CD38 MoAbs was 4.6 months (95% C.I. 1.6-7.6), while median OS was 15.3 months (95% C.I. 8.2-22.4) (Figure 2). Conclusion: Patient who become refractory to elotuzumab have guarded prognosis, particularly dismal among patients also refractory to anti-CD38 MoAb, defining a population with great need for novel therapies. Failure of elotuzumab-based therapy does not preclude disease control with anti-CD38 MoAb, particularly in combination. Disclosures Paul: Bristol Myer Squibb: Other: Stock and pension plan (past employee). Amarendra:Amgen: Consultancy; Celgene: Consultancy. Liedtke:Caelum: Membership on an entity's Board of Directors or advisory committees; celgene: Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees, Research Funding; Genentech/Roche: Research Funding; BlueBirdBio: Research Funding; Prothena: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen/Onyx: Consultancy, Honoraria, Research Funding; Gilead: Membership on an entity's Board of Directors or advisory committees, Research Funding. Hari:Kite Pharma: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Research Funding; Takeda: Consultancy, Honoraria, Research Funding; Sanofi: Honoraria, Research Funding; Janssen: Honoraria; Bristol-Myers Squibb: Consultancy, Research Funding; Amgen Inc.: Research Funding; Spectrum: Consultancy, Research Funding. Vij:Karyopharm: Honoraria; Jazz Pharmaceuticals: Honoraria; Janssen: Honoraria; Amgen: Honoraria; Takeda: Honoraria, Research Funding; Bristol Myer Squibb: Honoraria, Research Funding; Celgene: Honoraria, Research Funding. Usmani:Abbvie, Amgen, Celgene, Genmab, Merck, MundiPharma, Janssen, Seattle Genetics: Consultancy; Amgen, BMS, Celgene, Janssen, Merck, Pharmacyclics,Sanofi, Seattle Genetics, Takeda: Research Funding. Kumar:Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; KITE: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding. Costa:Karyopharm: Research Funding; Abbvie: Research Funding; Amgen: Honoraria, Research Funding; Celgene: Honoraria, Research Funding; BMS: Research Funding; Sanofi: Honoraria; Janssen: Research Funding.

Abstract Introduction Development of anti-CD38 monoclonal antibody therapies (MoABs), including daratumumab and isatuximab, have drastically changed the therapeutic landscape for management of relapsed and/or refractory multiple myeloma (RRMM). However, there is a paucity of information regarding response to treatment after progression on CD38 MoABs. This collaborative research study (MAMMOTH: Monoclonal Antibodies in Multiple Myeloma: Outcomes after Therapy Failure) investigates the therapeutic choices and outcomes of subsequent treatments after refractoriness to MoABs. Methods Patients from 14 US academic institutions with diagnosis of MM and refractory to daratumumab or isatuximab, administered alone or in combination, were evaluated. Patients were considered refractory to a CD38 MoAB if treated with at least 4 weeks of therapy and had evidence of progressive disease (PD) while on therapy or within 60 days after last dose. Time of progression was defined as time zero (T0). Data was collected by electronic platform and submitted to peer-based quality check for completeness and internal consistency. Results Two hundred and seventy-five patients with MM refractory to CD38 MoAB were evaluated; 249 (90.5%) of those patients who received at least one subsequent line of therapy were included in this analysis. The median age at T0 was 65 years (range 27-90) and 54% were male. At the time of diagnosis, 28% had ISS stage III disease and 29% had high-risk cytogenetics. Patients were heavily pre-treated at T0 with a median of 5 lines of therapy (range 2-17); most (74%) underwent a prior autologous stem cell transplant. The majority of patients were refractory to other anti-myeloma therapies including lenalidomide (78%), pomalidomide (65%), bortezomib (69%) and carfilzomib (45%). In total, 97.1% of patients were exposed to at least one immunomodulatory agent (IMiD) and one proteasome inhibitor (PI), 79.3% were ≥ triple-refractory (refractory to 1 IMiD, 1 PI and 1 CD38 MoAB), while 25.3% were penta-refractory (refractory to 2 IMiDs, 2 PIs and 1 CD38 MoAB). Responses to the next subsequent line of therapy after progression with CD38 MoAB are shown (Table). The overall response rate (ORR; ≥PR) of first regimen post-T0 was 31% with a median progression free survival (PFS) of 3.4 mo and median overall survival (OS) of 9.3 mo. Carfilzomib-based therapy resulted in an ORR of 32% with median PFS 4.2 mo and overall OS of 10.9 mo. The addition of an IMiD to daratumumab yielded an ORR of 37% with median PFS 4.5 mo and OS 12.6 mo. The addition of a PI to daratumumab yielded no responses. Elotuzumab-based therapy had an ORR of 21% with median PFS 2.6 mo and OS 8.3 mo. By multivariate analysis, alkylator-based therapies were found to have the highest ORR (OR 3.1, 95% CI 1.8-5.7, p<0.001), however, resulted in median PFS of only 3 mo and OS of 7.7 mo. Multivariate analysis evaluating for PFS and adjusting for refractoriness to prior therapies found lower risk of progression with carfilzomib-based therapy (HR 0.60, 95% CI 0.42-0.85, p=0.004, Figure 1) and with the addition of an IMiD to daratumumab (HR 0.64, 95% CI 0.43-0.94, p=0.02). The benefit of IMiD + daratumumab was essentially restricted to patients previously refractory to CD38 MoAB as monotherapy. These patients demonstrated improved PFS with subsequent daratumumab-combination therapy at time of progression compared with patients refractory to CD38 MoAB combination therapy (log-rank p=0.02, Figure 2). No particular regimen was associated with improved OS compared with the rest. Conclusions After progression on CD38 MoAB, treatment with carfilzomib-based regimens and the addition of an IMiD to daratumumab-monotherapy resulted in a higher ORR and PFS compared with other regimens. Alkylating agents resulted in the highest ORR but relatively short PFS and OS. The use of elotuzumab and the addition of a PI to daratumumab monotherapy resulted in relatively low response rates. Overall, progression after CD38 MoAB therapy is associated with a poor prognosis and innovative therapeutic strategies are needed. Disclosures Malek: Celgene: Consultancy, Speakers Bureau; Amgen: Consultancy, Speakers Bureau; Takeda: Consultancy, Speakers Bureau; Janssen: Consultancy, Speakers Bureau; Sanofi: Consultancy, Speakers Bureau. Paul:Bristol Myer Squibb: Other: Stock and pension plan (past employee). Neppalli:Celgene: Consultancy; Amgen: Consultancy. Liedtke:Amgen/Onyx: Consultancy, Honoraria, Research Funding; Caelum: Membership on an entity's Board of Directors or advisory committees; Genentech/Roche: Research Funding; Gilead: 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; Prothena: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; celgene: Research Funding; BlueBirdBio: Research Funding; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Hari:Takeda: Consultancy, Honoraria, Research Funding; Spectrum: Consultancy, Research Funding; Kite Pharma: Consultancy, Honoraria; Sanofi: Honoraria, Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Amgen Inc.: Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Janssen: Honoraria. Vij:Bristol-Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Jazz Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Jansson: Honoraria, Membership on an entity's Board of Directors or advisory committees; Karyopharma: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: 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, Research Funding. Usmani:Amgen, BMS, Celgene, Janssen, Merck, Pharmacyclics,Sanofi, Seattle Genetics, Takeda: Research Funding; Abbvie, Amgen, Celgene, Genmab, Merck, MundiPharma, Janssen, Seattle Genetics: Consultancy. Costa:Amgen: Honoraria, Research Funding; Celgene: Honoraria, Research Funding; BMS: Research Funding; Abbvie: Research Funding; Janssen: Research Funding; Karyopharm: Research Funding; Sanofi: Honoraria. Kumar:Roche: Research Funding; KITE: Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding; Merck: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees; Oncopeptides: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; KITE: Membership on an entity's Board of Directors or advisory committees, Research Funding.

Abstract History of prior cancer is a widespread exclusion criterion in cancer trials. Up to 80% of NCI-sponsored and 80% of industry-sponsored lung cancer trials exclude patients with a prior cancer. We suspect this exclusion is commonly applied in other cancer trials, although no definitive data exist. Prior cancer is especially common among older patients and those with certain cancer types. Among patients >65 years, 15.1% overall have prior cancer. In Multiple Myeloma, the most common plasma cell disorder (PCD), prevalence of prior cancer is as high as 17.4%. Examining the prior cancer exclusion criterion is important because the number of US cancer survivors is large and rapidly growing. Arbitrarily excluding cancer survivors from trials is not evidence-based and exclusion presumably arises from assumptions that higher mortality of patients with prior cancer could hinder study conduct and bias trial outcomes. However, few data exist to support this assumption of higher mortality. In fact, we demonstrated that lung cancer patients with a prior cancer have similar or lower mortality risk, compared to those without prior cancer. In this abstract, we reviewed prior cancer related eligibility criteria in three of the most common PCD (Multiple Myeloma, Amyloidosis and Waldenström Macroglobulinemia) clinical trials sponsored or endorsed by 5 major Co-Operative groups in North America (Table 1). We use descriptive statistics (n, %) and Fisher's exact tests to describe characteristics of trials with and without exclusion criteria. Of 33 trials, 26 (79%) excluded patients with prior cancer as follows - active cancer (12%), within 2-3 years of PCD diagnosis (9%), or within 5 years of PCD diagnosis (55%). Many trials had exceptions to prior cancer exclusion. Specifically, 67% of trials allowed non-melanoma skin cancer, 58% allowed in-situ cervical cancer, 12% allowed early stage prostate cancer. Table 2 shows the association between clinical trial characteristics and prior cancer exclusion. There was no association between prior cancer exclusion and phase of study, transplant studies, or survival end point. Exclusion criteria varied across year of activation (p=0.01); for example, 75% of studies activated 1990-1999 excluded prior cancer, compared to 100% of studies activated after 2010. Type of PCD was marginally associated with exclusion criteria (p=0.08); 74% of Multiple Myeloma trials excluded patients with prior cancer compared to 100% of the Amyloidosis and Waldenström Macroglobulinemia trials. Conclusion: A substantial proportion of potential participants may be excluded from PCD clinical trials because of a history of prior cancer. This practice impacts accrual, generalizability, and fair access to cutting-edge treatments and the highest level of clinical care. As treatment outcomes for other cancers continue to improve, it is likely that the prevalence of multiple primary cancers will increase. This exclusion criterion is applied widely across studies, including more than two-thirds of those with non-survival endpoints. Our study is the first to examine the prevalence and potential impact of prior cancer exclusion in PCD clinical trials. Using population-based cancer registry data, we plan to undertake further research to understand the appropriateness and ramifications of this standard exclusion policy in PCD cancer trials. Disclosures Collins: Agios: Research Funding; Bristol Myers Squibb: Research Funding; Celgene Corporation: Research Funding; Arog Pharmaceuticals: Research Funding. Devine:Kiadis Pharma: Consultancy. Usmani:Amgen, BMS, Celgene, Janssen, Merck, Pharmacyclics,Sanofi, Seattle Genetics, Takeda: Research Funding; Abbvie, Amgen, Celgene, Genmab, Merck, MundiPharma, Janssen, Seattle Genetics: Consultancy. Anderson:Amgen: Speakers Bureau; Takeda: Speakers Bureau; Celgene: Speakers Bureau. Kumar:Janssen: 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; Roche: Research Funding; AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding; Merck: Membership on an entity's Board of Directors or advisory committees, Research Funding; Oncopeptides: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; KITE: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; KITE: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding.

Abstract Introduction Proteasome inhibitors (PIs) and immunomodulatory drugs (IMiDs) have significantly improved survival in patients with multiple myeloma (MM). Refractoriness to PIs and IMiDs results in poor outcomes with a median survival of about 13 months.Daratumumab and isatuximab are CD38-targeting monoclonal antibodies (MoABs) with remarkable activity in relapsed and refractory MM. The outcome of MM patients in US clinical practice who becomes refractory to CD38 MoABs is unknown. The aim of this multicenter, retrospective study is to investigate the natural history of patients with MM who become refractory to CD38 MoABs (Monoclonal Antibodies in Multiple Myeloma: Outcomes after Therapy Failure: MAMMOTH study). Methods We identified patients from 14 academic institutions in the US with diagnosis of active MM and refractory to daratumumab or isatuximab, administered alone or in combination. Patients were considered refractory to CD38 MoAB if treated with at least 4 weeks of therapy and had evidence of progressive disease (PD) while on therapy or within 60 days after last dose. The time when patients met the above criteria of progression was defined as time zero (T0). Data including patient-disease characteristics and all therapies administered before and after T0 were collected with an electronic platform and submitted to peer-based quality check for completeness and internal consistency. For survival outcome analysis, patients were classified into three groups: "Penta-refractory" (refractory to 1 CD38 MoAB + 2 PIs + 2 IMiDs), "Triple-refractory and quad-refractory" (refractory to 1 CD38 MoAB + 1 PI + 1/2 IMiDs, or 1 CD38 MoAB + 1/2 PIs + 1 IMiD), and "Not triple-refractory" (refractory to 1 CD38 MoAB, and not both of a PI and an IMiD). Responses were evaluated using the IMWG criteria. Results Two hundred and seventy-five patients were included in this study; median age at T0 was 65 years (range 27-90). Fifty five percent of patients were males, 52% had IgG isotype, 29% had ISS stage III disease, and 29% had high-risk cytogenetics at diagnosis. Median interval from diagnosis of MM to T0 was 50.1 months (mo) (range 2.5-230.1). Patients received a median of 4 lines of treatment (1-16) prior to the CD38 MoAB-containing regimen; 72% underwent prior autologous transplant. Daratumumab-refractory patients formed a majority (256, 93.1%) of this cohort. Most of the patients were refractory to lenalidomide (77%), pomalidomide (65%), bortezomib (68%), and carfilzomib (47%). Seventy patients (25.5%) were "penta-refractory" and 148 (53.8%) were "triple-refractory and quad-refractory". Median follow-up from T0 for survivors was 10.6 mo (range 1.9-42.3 mo). The median overall survival (OS) from T0 for the entire cohort was 8.6 mo (95% C.I. 7.2-9.9); OS for the groups based on refractoriness to prior treatments are shown (Figure). Two hundred and forty-nine patients (90.5%) received at least one line of treatment after T0, (median 2, range 1-10). The response rates and depth of responses to each line of treatment post T0 are shown (Table). Among patients who received ≥ 1 subsequent treatment, the median PFS and OS from T0 were 3.4 (95% C.I. 2.8-4.0) mo and 9.3 (95% C.I. 8.1-10.6) mo, respectively; the median OS for the 26 patients who received no further treatment was only 1.3 (95% C.I. 0.6-1.9) mo. By multivariate analysis, penta-refractoriness (HR 2.4, p <0.001), high-risk cytogenetics (HR 1.5, p=0.01), elevated LDH (HR 2, p<0.001) and creatinine > 2 (HR 2.4, p=0.01) at the onset of CD38-based therapy predicted inferior OS. Conclusions Patients with MM who become refractory to CD38 MoAB are increasingly less responsive to subsequent therapies. While survival is particularly dismal for penta-refractory patients, the outcomes are poor even for patients who are not refractory to other mainstream MM agents. The MAMMOTH study defines a MM population in urgent need for new therapies, and provides benchmark OS, PFS and response data for subsequent investigational therapies in this setting. Disclosures Malek: Celgene: Consultancy, Speakers Bureau; Janssen: Consultancy, Speakers Bureau; Takeda: Consultancy, Speakers Bureau; Sanofi: Consultancy, Speakers Bureau; Amgen: Consultancy, Speakers Bureau. Paul:Bristol Myer Squibb: Other: Stock and pension plan (past employee). Neppalli:Amgen: Consultancy; Celgene: Consultancy. Liedtke:Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Prothena: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen/Onyx: Consultancy, Honoraria, Research Funding; BlueBirdBio: Research Funding; celgene: Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees, Research Funding; Gilead: Membership on an entity's Board of Directors or advisory committees, Research Funding; Genentech/Roche: Research Funding; Caelum: Membership on an entity's Board of Directors or advisory committees. Hari:Amgen Inc.: Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Spectrum: Consultancy, Research Funding; Kite Pharma: Consultancy, Honoraria; Bristol-Myers Squibb: Consultancy, Research Funding; Sanofi: Honoraria, Research Funding; Janssen: Honoraria; Takeda: Consultancy, Honoraria, Research Funding. Vij:Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; 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; Bristol-Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Karyopharma: Honoraria, Membership on an entity's Board of Directors or advisory committees; Jansson: Honoraria, Membership on an entity's Board of Directors or advisory committees; Jazz Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees. Usmani:Abbvie, Amgen, Celgene, Genmab, Merck, MundiPharma, Janssen, Seattle Genetics: Consultancy; Amgen, BMS, Celgene, Janssen, Merck, Pharmacyclics,Sanofi, Seattle Genetics, Takeda: Research Funding. Kumar:Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; KITE: Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding. Costa:Karyopharm: Research Funding; Sanofi: Honoraria; Janssen: Research Funding; BMS: Research Funding; Abbvie: Research Funding; Amgen: Honoraria, Research Funding; Celgene: Honoraria, Research Funding.

Abstract Background: Each additional line of therapy is associated with lower rates of deeper responses, shorter durations of treatment-free intervals, and increased rates of toxicities/comorbidities in patients with multiple myeloma (MM; Yong K, et al. Br J Haematol 2016. 175[2]:252-264), all of which are factors that contribute to treatment discontinuation. In order to characterize the newly diagnosed MM (NDMM) patient population in the United States not treated with a stem-cell transplant based on the number of subsequent lines of therapy (LOT) received, we examined baseline patient characteristics and pre-existing comorbidities, frontline treatment patterns, and attrition rates for these patients according to whether subsequent LOT was received or not received. Methods: NDMM patients were identified from 3 US patient-level data sources: the Surveillance, Epidemiology, and End Results (SEER)-Medicare Linked database (from January 2007 through December 2014), the OPTUM™ Commercial Claims database (from January 2000 through March 2017), and the OPTUM™ Electronic Medical Records (EMR) database (from January 2007 through March 2016). Patients included in the assessment had 1) an index diagnosis of MM on or after 1 January 2007, 2) known gender, 3) medical prescription coverage in place at diagnosis, 4) a 1-year look-back period prior to the index diagnosis, 5) no prior malignancies in the 1-year period prior to index diagnosis, and 6) received ≥1 LOT. The analysis was limited to patients who did not receive stem cell transplantation at any time during their follow-up. Descriptive and logistic regression analyses were conducted to characterize and compare patients who received or did not receive a subsequent LOT. Results: The analysis included a total of 7,724 patients (1 LOT only: n = 3,906; 2+ LOT: n = 3,818). A summary of baseline patient characteristics and pre-existing comorbidities by LOT is summarized in Table 1. Patients who received a subsequent LOT vs those that did not were significantly younger (median age 72.0 vs 74.0 years; P <0.0001) and had significantly lower mean Charleston Comorbidity Index (CCI) score due to lower occurrence of renal, cardiac, and hepatic comorbidities (Table 1). Older age at diagnosis and presence of renal, congestive heart failure (CHF), hepatic, and pulmonary comorbidities were associated with higher attrition. The regimens used in frontline treatment included bortezomib/dexamethasone (26%), lenalidomide/dexamethasone (21%), bortezomib/lenalidomide/dexamethasone (11%), a bortezomib/alkylator ± steroid combination (6%), bortezomib monotherapy (10%), lenalidomide monotherapy (6%), thalidomide monotherapy (4%), and other (17%). The proportions of patients progressing to each subsequent line of therapy are shown in Table 2. In total, 49% of patients went on to receive a second line of therapy, and 55% of patients receiving a second line of therapy went on to receive a third line of therapy. The incidence of patients not receiving subsequent lines of therapy due to death or being lost to follow up by LOT is summarized in Table 2. Conclusions: A majority of non-transplant patients with NDMM in the study did not progress to subsequent lines of therapy, with attrition as high as 50% per line of therapy and only <8% of patients reaching LOT 5. This high level of attrition is associated with older age and poor comorbidity status of non-transplant patients with NDMM. Therefore, utilizing the most optimal regimens upfront (rather than reserving them for later lines) is warranted. Disclosures Fonseca: Mayo Clinic: Employment; Amgen: Consultancy. Usmani:Abbvie, Amgen, Celgene, Genmab, Merck, MundiPharma, Janssen, Seattle Genetics: Consultancy; Amgen, BMS, Celgene, Janssen, Merck, Pharmacyclics,Sanofi, Seattle Genetics, Takeda: Research Funding. Mehra:Janssen Global Services, LLC: Employment. Slavcev:Janssen Global Services, LLC: Employment. Ukropec:Janssen Scientific Affairs, LLC: Employment. Lam:Janssen Global Services, LLC: Employment. Potluri:SmartAnalyst Inc.: Employment.

Abstract Eukaryotic translation initiation factor 5A (eIF5A) has been implicated in the regulation of cell proliferation, apoptosis, and inflammation, and is the only known protein to be modified by hypusination. Hypusinated eIF5A, the predominant form of eIF5A in cancer cells, is involved in cell survival and activation of inflammatory pathways. In contrast, accumulation of the unhypusinated form of eIF5A is associated with apoptosis and mutants of eIF5A that cannot be hypusinated (e.g. eIF5AK50R) are pro-apoptotic. SNS01-T was designed to treat B-cell cancers and consists of two active components: a plasmid DNA expressing the pro-apoptotic eIF5AK50R under the control of a B cell-specific promoter, and an siRNA against an untranslated region of native eIF5A mRNA. When these two components are combined with linear polyethyleneimine (PEI), the nucleic acids are condensed into nanoparticles for protection from degradation in the blood and enhanced cellular delivery. The mode of action of SNS01-T is siRNA-mediated inhibition of hypusinated eIF5A and simultaneous over-expression of pro-apoptotic eIF5AK50R to induce cell death. In vitro cell studies and in vivo xenograft studies have demonstrated the efficacy of this approach. The safety and tolerability of intravenous administration of SNS01-T is being investigated in a first-in-human Phase1b/2a study in patients with relapsed or refractory multiple myeloma (MM), mantle cell lymphoma (MCL) or diffuse large B cell lymphoma (DLBCL). Eligible patients are being enrolled sequentially into four cohorts at increasing doses. Each patient receives an intravenous infusion of SNS01-T twice weekly for 6 consecutive weeks. Eligible patients must have been diagnosed with MM according to IMWG criteria, or with MCL or DLBCL with histologic confirmation. Patients also must have measurable disease, have relapsed or refractory disease after two or more prior treatment regimens, have a life expectancy of at least 3 months, and not be eligible to receive any other standard therapy known to extend life expectancy. The primary objective is to evaluate the safety and tolerability of multiple escalating doses of SNS01-T. Secondary objectives include analysis of pharmacokinetics, immunogenicity, pro-inflammatory cytokines, and therapeutic efficacy. The required 3 patients per cohort have completed the dosing schedule in cohorts 1 and 2 from a total of 10 patients enrolled (9 patients with MM and 1 with DLBCL). Of the ten patients enrolled, four completed the full treatment period, two did not complete dosing but were evaluable for safety, and four (three in cohort 1 and one in cohort 2) discontinued treatment after fewer than 8 doses and were not evaluable. There were no drug-related serious adverse events or dose limiting toxicities in either cohort 1 or 2. In cohort 1 (0.0125 mg/kg SNS01-T), two of three evaluable patients did not progress on treatment and were considered stable at week 3 and week 6, the end of the dosing regimen. The third patient progressed after receiving 10 of the 12 doses and was evaluable for safety. In cohort 2 (0.05 mg/kg), 3 patients (2 with MM and 1 with DLBCL) were evaluable for safety. Stabilization of serum monoclonal protein levels was observed in one MM patient of cohort 2. Two patients (1 with MM and 1 with DLBCL) progressed after receiving 8 of the 12 doses and were evaluable for safety. Results from ongoing pharmacokinetic studies, immunogenicity studies, and quantification of pro-inflammatory cytokines will be discussed. The planned dose levels for the third and fourth groups are 0.2 and 0.375 mg/kg, respectively. The results to date of this first-in-human clinical trial indicate that SNS01-T can be administered safely and the MTD has not yet been reached (Clinical Trials.gov Identifier: NCT01435720). Disclosures: Barranco: Senesco Technologies: Consultancy. Usmani:Celgene, Onyx, Millenium: Consultancy, Research Funding, Speakers Bureau. van Rhee:Jansen&Jansen: Research Funding. Thompson:Senesco Technologies: Consultancy, Equity Ownership, Membership on an entity’s Board of Directors or advisory committees, Research Funding. Taylor:Senesco Technologies: stock options Other. Dondero:Senesco Technologies: Employment. Browne:Senesco Technologies Inc.: Employment, Equity Ownership, Membership on an entity’s Board of Directors or advisory committees. Siegel:Celgene, Millenium, Onyx (same for all): Honoraria, Membership on an entity’s Board of Directors or advisory committees, Speakers Bureau.