Kaufman, Jonathan L.

Introduction: Chimeric antigen receptor (CAR) T cell therapy directed against B cell maturation antigen (BCMA) has shown promising results for the treatment of relapsed refractory multiple myeloma (RRMM) in several phase 1 studies. Persistence of CAR T cells post infusion may be one determinant of duration of response. bb21217 is a next-generation anti-BCMA CAR T cell therapy based on investigational therapy idecabtagene vicleucel (bb2121) (Friedman 2018, Hum Gene Ther 29:585) that uses the same lentiviral CAR T design as bb2121, but adds the phosphoinositide 3-kinase inhibitor bb007 during ex vivo culture to enrich the drug product for memory-like T cells. Evidence suggests that CAR T cells with this phenotype may be more persistent and more potent than unselected CAR T cells. CRB-402 is a first-in-human study of bb21217 in patients with RRMM designed to assess safety, pharmacokinetics, efficacy and duration of effect. Methods: CRB-402 (NCT03274219) is an ongoing, multi-center phase 1 dose escalation trial of bb21217 planning to enroll 74 patients with RRMM who received ≥ 3 prior regimens, including a proteasome inhibitor and an immuno-modulatory agent, or are double-refractory to both classes. During dose escalation, enrollment is restricted to patients with ≥ 50% BCMA expression by IHC on malignant plasma cells. Peripheral blood mononuclear cells are collected via leukapheresis and sent to a central facility for transduction, expansion and release testing prior to being returned to the site for infusion. Patients undergo lymphodepletion with fludarabine (30 mg/m2) and cyclophosphamide (300 mg/m2) daily for 3 days, then receive bb21217 as a single infusion. Planned dose levels are 150, 450, 800, and 1,200 x 106 CAR+ T cells and intermediate dose levels are allowed. The primary outcome measure is incidence of adverse events (AEs), including dose-limiting toxicities (DLTs). Additional outcome measures are quality and duration of clinical response assessed according to the IMWG Uniform Response Criteria, evaluation of minimal residual disease (MRD), progression-free and overall survival, and quantification of CAR+ T cells in blood. Results: Asof April 20, 2019, 22 patients (median age 63 [min;max 42 to 74]) have received bb21217 (12 at 150, 6 at 300 and 4 at 450). Eleven had high tumor burden, defined as ≥ 50% bone marrow plasma cells pre-infusion. Patients had a median of 7 (min;max 4 to 17) prior lines of therapy and 18/22 had prior autologous stem cell transplant; 7/22 had high-risk cytogenetics. Of the 22 patients, 19 received prior daratumumab, 13 received prior Bort/Len/Car/Pom/Dara. Median follow-up after bb21217 infusion was 23 weeks (<1 to 77 weeks). As of data cut-off, 13/22 patients developed cytokine release syndrome (CRS; 5 G1, 7 G2, 1 G3) and responded to supportive care, tocilizumab and/or corticosteroids. Five patients developed neurotoxicity [1 G1, 2 G2, 1 G3 (vertigo/dizziness), 1 G4 (encephalopathy, previously reported)]. For the 1 patient with G4 neurotoxicity, G3 CRS was also reported; both have resolved. A total of 18 patients were evaluable for response with ≥ 2 months of follow up or PD within 2 months. Fifteen (83%) patients demonstrated clinical response per IMWG criteria. Six of these subjects subsequently progressed. Nine patients remained in response, including 2 patients with ongoing response at months 15 and 18. MRD negative results at 10-5 nucleated cells or better were obtained by NGS in 10/10 evaluable responders at month 1. Overall, 6/8 patients evaluable at 6 months and 2/2 patients evaluable at 12 months had detectable CAR T cells in blood. Updated data from this study will be presented, including extended follow-up on the initial patients treated and early clinical and CAR T cell persistence data from at least 15 additional patients treated with up to 450 x 106 CAR+ T cells. Conclusions: The adverse events observed to date were manageable and consistent with known toxicities of CAR T therapies. Initial efficacy results with bb21217 CAR T therapy in heavily pretreated RRMM are encouraging, with 83% of patients demonstrating clinical response. Emerging data demonstrate long-term persistence of CAR T cells in long-term responders. Updated data to be presented will help determine whether treatment with bb21217 results in sustained CAR T cell persistence and durable clinical responses, and whether bb21217 is tolerated at higher doses. Disclosures Berdeja: AbbVie Inc, Amgen Inc, Acetylon Pharmaceuticals Inc, Bluebird Bio, Bristol-Myers Squibb Company, Celgene Corporation, Constellation Pharma, Curis Inc, Genentech, Glenmark Pharmaceuticals, Janssen Biotech Inc, Kesios Therapeutics, Lilly, Novartis, Poseida: Research Funding; Poseida: Research Funding; Amgen Inc, BioClinica, Celgene Corporation, CRISPR Therapeutics, Bristol-Myers Squibb Company, Janssen Biotech Inc, Karyopharm Therapeutics, Kite Pharma Inc, Prothena, Servier, Takeda Oncology: Consultancy. Alsina:Bristol-Myers Squibb: Research Funding; Janssen: Speakers Bureau; Amgen: Speakers Bureau. Shah:Celgene, Janssen, Bluebird Bio, Sutro Biopharma: Research Funding; Poseida: Research Funding; Bristol-Myers Squibb: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Nkarta: Consultancy, Membership on an entity's Board of Directors or advisory committees; Kite: Consultancy, Membership on an entity's Board of Directors or advisory committees; Teneobio: Consultancy, Membership on an entity's Board of Directors or advisory committees; Indapta Therapeutics: Equity Ownership; Genentech, Seattle Genetics, Oncopeptides, Karoypharm, Surface Oncology, Precision biosciences GSK, Nektar, Amgen, Indapta Therapeutics, Sanofi: Membership on an entity's Board of Directors or advisory committees; University of California, San Francisco: Employment. Siegel:Takeda: 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; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Jagannath:Celgene: Consultancy; Novartis: Consultancy; BMS: Consultancy; Medicom: Speakers Bureau; Multiple Myeloma Research Foundation: Speakers Bureau; Merck: Consultancy. Madduri:Abbvie: Consultancy; Celgene: Consultancy; Takeda: Consultancy; undation Medicine: Consultancy. Kaufman:Janssen: Honoraria; Pharmacyclics: Membership on an entity's Board of Directors or advisory committees; AbbVie: Consultancy; Takeda: Consultancy; Amgen: Consultancy; Winship Cancer Institute of Emory University: Employment; Bristol-Myers Squibb: Consultancy; Incyte: Consultancy; Karyopharm: Membership on an entity's Board of Directors or advisory committees; TG Therapeutics: Consultancy; Celgene: Consultancy. Munshi:Janssen: Consultancy; Amgen: Consultancy; Takeda: Consultancy; Oncopep: Consultancy; Celgene: Consultancy; Adaptive: Consultancy; Abbvie: Consultancy. Rosenblatt:BMS: Other: Advisory Board ; Parexel: Consultancy; Imaging Endpoint: Consultancy; Partner Tx: Other: Advisory Board; Dava Oncology: Other: Education; BMS: Research Funding; Amgen: Other: Advisory Board; Celgene: Research Funding; Merck: Other: Advisory Board. Turka:bluebird bio: Employment. Lam:bluebird bio: Employment. Massaro:bluebird bio: Employment. Campbell:Celgene Corporation: Employment, Equity Ownership. Hege:Celgene Corporation: Employment, Equity Ownership, Patents & Royalties; Mersana Therapuetics: Membership on an entity's Board of Directors or advisory committees; Arcus Biosciences: Membership on an entity's Board of Directors or advisory committees; Society for Immunotherapy of Cancer: Membership on an entity's Board of Directors or advisory committees. Petrocca:bluebird bio: Employment. Raje:Amgen Inc.: Consultancy; Bristol-Myers Squibb: Consultancy; Celgene Corporation: Consultancy; Takeda: Consultancy; Janssen: Consultancy; Merck: Consultancy.

Background Venetoclax (Ven) is a selective, small molecule inhibitor of anti-apoptosis protein Bcl-2 that has antitumoral activity against multiple myeloma (MM), notably those with translocation t(11;14). Dexamethasone (d) has shown to enhance the expression of BCL-2 and pro-apoptotic protein Bim, shifting its binding towards Bcl-2 and sensitizing MM cells to Ven. This Phase 1/2 open-label trial is evaluating the safety and efficacy of the combination of Ven+d as a therapeutic approach to improve clinical outcomes in patients with t(11;14) Relapsed/Refractory (R/R) MM. Methods This ongoing study (NCT01794520) has 2 distinct phases. Phase 1 (P1) consisted of separate dose escalation, safety expansion, and Ven+d combination cohorts. The phase 2 (P2) portion is an expansion cohort of Ven+d to further evaluate its efficacy. The safety and efficacy of the Ven+d cohorts from P1 and P2 are reported here. Eligible patients (pts) were adults with t(11;14) R/R MM ≥18 years of age. Key eligibility criteria for the Ven+d cohort in P1 included prior treatment with a proteasome inhibitor (PI) and an immunomodulatory drug (IMID), and an ECOG score ≤1. In P2, eligibility included an ECOG score ≤2, disease progression on or within 60 days from the last dose on previous treatment and having received at least two lines of therapy with a PI, IMID, daratumumab, and glucocorticoids. Additional inclusion criteria for both phases included measurable disease and adequate bone marrow function in all pts, and the presence of t(11;14) determined by fluorescence in-situ hybridization. In both phases, pts received oral Ven 800 mg/day + oral d 40 mg (20 mg for pts ≥75 years of age) on days 1, 8, and 15 of each 21-day cycle. In P1, preliminary efficacy was assessed as the overall response rate (ORR), time to progression (TTP), progression free survival (PFS), and duration of response (DOR) of Ven+d based on the 2011 International Uniform Response Criteria for MM. Efficacy in P2 further evaluated ORR, very good partial response (VGPR) or better, PFS, DOR, TTP, and overall survival (OS) using 2016 IMWG response criteria. Results In P1, as of 15thApril, 2019, 20 pts were enrolled (17 [85%] male; median age, 63 years [range, 46-77]). The median number of prior therapies received was 2.5 (range: 1-7). Nineteen pts (95%) discontinued the study (18 due to progressive disease and 1 underwent transplant). The treatment-emergent adverse events (TEAEs) are summarized in the Table. Most frequent TEAEs were insomnia (45%), hypophosphatemia (40%), hyperglycemia (35%), diarrhea (35%), and thrombocytopenia (30%). Predominant Grade 3 or 4 TEAEs included neutropenia (21%), lymphopenia (29%), and hypophosphatemia (20%). The most common serious TEAE was tumor lysis syndrome (TLS) (10%). No deaths were reported in the treatment-emergent period. ORR was achieved by 13 (65%) and ≥VGPR was achieved by 6 (30%) pts respectively. Partial response (PR) was observed in 7 (35%) pts and stable disease (SD) in 4 (20%) pts. Median time to first response was 1.4 mos (95% CI: 0.7, 2.8). The DOR was 13.1 mos (95% CI: 10.9, 21.9). Median PFS and TTP were both 12.4 mos (95% CI 3.6, 20.9). In P2, as of March 18, 2019, 31 pts were enrolled (18 [58%] male; median age, 65 years [range, 48-80]). The median number of prior therapies received were 5 (range: 1-9). Eight (26%) pts discontinued the study (6 deaths, 1 withdrew consent, 1 due to physician's decision). The most frequent TEAEs reported were diarrhea (32%), nausea (26%) and lymphopenia (32%). The most frequent Grade 3 or 4 TEAEs were lymphopenia (32%), thrombocytopenia (11%), and hypertension (10%). Most common serious TEAE was sepsis (10%). Six (19%) deaths were reported (5 due to progressive disease and 1 due to adverse event). In the intention to treat population, the median TTR was 0.7 mos (range: 0.6-1.5). ORR was achieved by 14 (45%) and >VGPR was observed in 8 (26%) pts. PR was observed in 6 (13%) pts and SD in 8 (26%) pts. Median PFS, DOR, and OS were not reached at the time of data analysis. The 9-mo estimates for PFS, DOR, and OS were 57% (95% CI: 19% 82%), 66% (95% CI: 16%, 91%), and 71% (95% CI: 44%, 87%) respectively. Conclusion In both phases of this study, Ven+d was efficacious and demonstrated tolerable safety in pts with t(11;14) R/R MM. These results support further investigation of Ven combinations in this pt population. This combination is also being investigated in the ongoing Phase 3 trial M13-494 (CANOVA) in t(11;14) positive R/R MM. Disclosures Kaufman: Takeda: Consultancy; Pharmacyclics: Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy; Bristol-Myers Squibb: Consultancy; Incyte: Consultancy; Karyopharm: Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria; AbbVie: Consultancy; Winship Cancer Institute of Emory University: Employment; Amgen: Consultancy; TG Therapeutics: Consultancy. Gasparetto:Celgene: Consultancy, Honoraria, Other: Travel, accommodations, or other expenses paid or reimbursed ; Janssen: Consultancy, Honoraria, Other: Travel, accommodations, or other expenses paid or reimbursed ; BMS: Consultancy, Honoraria, Other: Travel, accommodations, or other expenses paid or reimbursed . Schjesvold:Takeda: 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; Novartis: Honoraria; Oncopeptides: 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; MSD: Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; SkyliteDX: Honoraria. Moreau:Takeda: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; AbbVie: Consultancy, Honoraria; Celgene: Consultancy, Honoraria. 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. Boise:Genentech Inc.: Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Honoraria, Research Funding. Alzate:AbbVie Inc: Employment, Other: Stock/stock options. Macartney:AbbVie Inc: Employment, Other: Stock/stock options. Pesko:AbbVie: Employment, Other: Stock/stock options. Salem:AbbVie: Employment, Other: Stock/stock options. Ross:AbbVie: Employment, Other: Stock/stock options. Hong:Genentech Inc.: Employment, Equity Ownership; Roche: Equity Ownership. Maciag:AbbVie: Employment, Other: Stock/stock options. Pauff:AbbVie Inc: Employment, Other: may own stock or stock options. Kumar:Takeda: Research Funding; Celgene: Consultancy, Research Funding; Janssen: Consultancy, Research Funding. OffLabel Disclosure: Venetoclax is a BCL-2 inhibitor that is FDA-approved in some indications. This presentation will focus on venetoclax for treatment in multiple myeloma, which is not an approved indication.

Background: Maintenance therapy with lenalidomide post-autologous stem cell transplantation (ASCT) has shown to improve progression-free survival (PFS) in multiple myeloma (MM), and has largely become the standard of care. However, toxicity leads to early discontinuation in nearly one-third of patients and additional options are needed (McCarthy, et al, JCO, 2017). Ixazomib is another maintenance option that has been shown to improve PFS; however, studies comparing lenalidomide and ixazomib are lacking. In this randomized phase 2 study, we analyzed the safety and efficacy of using lenalidomide and ixazomib as part of consolidation and maintenance therapies after ASCT (NCT02253316). Methods: Eligible patients, age 18-70 with newly diagnosed MM undergoing ASCT during first-line treatment, were consented prior to ASCT. Approximately 4 months following ASCT, patients received 4 cycles of consolidation therapy with IRd [ixazomib 4 mg on days 1, 8 and 15 of a 28-day cycle, lenalidomide 15 mg on days 1 through 21, and dexamethasone 40 mg on days 1, 8 and 15]. Primary data on IRd consolidation were presented at ASH 2018 (Abstract 109920). One month after the last consolidation cycle, patients were randomized (1:1) to maintenance therapy with single-agent ixazomib (4 mg on days 1, 8 and 15 of a 28-day cycle) or lenalidomide (10 mg daily months 1-3 followed by 15 mg for months 4+). The arms were stratified based on MRD-status post-consolidation. In total, 237 patients were enrolled from 10 US centers. This abstract coincides with planned interim analysis 3 which is the first comparison of ixazomib and lenalidomide maintenance. While the study was not powered to compare PFS between the two arms, the sample will provide a reasonable power to estimate non-inferiority. There is a planned stopping rule for non-inferiority set at a hazard ratio of >1.3 in favor of lenalidomide. Secondary end-points include MRD-negativity following 12 cycles and toxicity. Results: At time of abstract submission, 215 patients had completed IRd consolidation and 191 had begun maintenance. 90 were randomized to ixazomib and 94 to lenalidomide. 7 patients were not randomized due to toxicity during consolidation; data from these patients are not included in the analyses. The characteristics of the two arms are summarized in Table 1. Hematologic toxicity has been infrequent with ixazomib with neutropenia and thrombocytopenia occurring in 11% and 23% of patients. In comparison, neutropenia and thrombocytopenia occurred in 45% and 35% of patients on lenalidomide. The most common non-hematologic toxicities in both arms have been GI-related and infections, both expected events. 16% of patients on ixazomib have experienced Grade 3-4 non-hematologic toxicity compared to 34% on lenalidomide. No grade 3 or higher peripheral neuropathy has been reported in either arm. 11% of patients on ixazomib have discontinued due to toxicity and another 9% have required a dose reduction to 3mg. Lenalidomide toxicity has led to discontinuation in 15% of patients and another 12% were dose reduced to 5mg. Only 45% of patients receiving 4+ cycles of lenalidomide were able to titrate to the 15mg dose. After a median follow-up of 11.2 months from randomization (19.7 months post-ASCT), 30% of patients on ixazomib have discontinued treatment due to disease progression. After a median follow-up of 12.3 months from randomization (20.2 months post-ASCT), 18% patients on lenalidomide have discontinued treatment due to disease progression. Conclusion: Ixazomib and lenalidomide maintenance have been well tolerated to date. A comparison of PFS is currently being conducted as part of interim analysis 3 and final results will be presented, representing the first report directly comparing lenalidomide and ixazomib maintenance. Table 1: Disclosures Vij: Genentech: Honoraria; Karyopharm: Honoraria; Celgene: Honoraria, Research Funding; Bristol-Myers Squibb: Honoraria, Research Funding; Takeda: Honoraria, Research Funding; Janssen: Honoraria; Sanofi: Honoraria. Martin:Amgen, Sanofi, Seattle Genetics: Research Funding; Roche and Juno: Consultancy. Fiala:Incyte: Research Funding. Deol:Novartis: Other: Advisory board; Kite: Other: Advisory board; Agios: Other: Advisory board. Kaufman:Celgene: Consultancy; Winship Cancer Institute of Emory University: Employment; Amgen: Consultancy; Bristol-Myers Squibb: Consultancy; Pharmacyclics: Membership on an entity's Board of Directors or advisory committees; AbbVie: Consultancy; Janssen: Honoraria; Incyte: Consultancy; Karyopharm: Membership on an entity's Board of Directors or advisory committees; TG Therapeutics: Consultancy; Takeda: Consultancy. Hofmeister:Karyopharm: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Oncopeptides: Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria; Nektar: Honoraria, Membership on an entity's Board of Directors or advisory committees; Imbrium: Membership on an entity's Board of Directors or advisory committees. Gregory:Poseida: Research Funding; Celgene: Speakers Bureau; Amgen: Speakers Bureau; Takeda: Speakers Bureau. Berdeja:AbbVie Inc, Amgen Inc, Acetylon Pharmaceuticals Inc, Bluebird Bio, Bristol-Myers Squibb Company, Celgene Corporation, Constellation Pharma, Curis Inc, Genentech, Glenmark Pharmaceuticals, Janssen Biotech Inc, Kesios Therapeutics, Lilly, Novartis, Poseida: Research Funding; Poseida: Research Funding; Amgen Inc, BioClinica, Celgene Corporation, CRISPR Therapeutics, Bristol-Myers Squibb Company, Janssen Biotech Inc, Karyopharm Therapeutics, Kite Pharma Inc, Prothena, Servier, Takeda Oncology: Consultancy. Chari:Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol-Myers Squibb: Consultancy; Celgene: 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; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Karyopharm: Consultancy, Membership on an entity's Board of Directors or advisory committees; Array Biopharma: Research Funding; GlaxoSmithKline: Research Funding; Novartis Pharmaceuticals: Research Funding; Oncoceutics: Research Funding; Pharmacyclics: Research Funding; Seattle Genetics: 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. Rosko:Vyxeos: Other: Travel support.

Abstract Background: Isatuximab (SAR650984) is a humanized IgG1 monoclonal antibody that binds selectively to a unique epitope on the human CD38 receptor. In the dose escalation part of the Phase I portion of the trial (NCT01749969), isatuximab ≥10 mg/kg IV given every other week (q2w) or 10 mg/kg weekly (qw) induced responses in 6/19 recipients (ORR 32%). Responses were noted at doses as low as 1 mg/kg q2w. The maximum tolerated dose (up to 20 mg/kg IV qw) was not reached. The most common treatment-emergent adverse events (TEAEs) were fatigue and nausea; few serious grade 3/4 TEAEs were reported (pneumonia 6%). The most common category of drug-related TEAE involved infusion-associated reactions (IARs) occurring in half of the patients, with grade 3/4 IARs in <5% of the patients. Based on promising Phase I activity, a Phase II dose finding study was added to investigate single-agent isatuximab in patients with relapsed or refractory myeloma (RRMM). Methods: In Phase II, eligible patients were originally randomly assigned (1:1:1) to one of 3 treatment groups: 3 mg/kg q2w, 10 mg/kg q2w, and 10 mg/kg q2w x 4 doses then q4w. A 4th treatment group was enrolled at a higher isatuximab dose with an optimized schedule of 20 mg/kg qw x 4 doses then q2w. Patient assignment was stratified by prior anti-myeloma therapy (Stratum 1: prior treatment with pomalidomide (POM) and/or carfilzomib (CAR); Stratum 2: no prior POM or CAR). Patients continued therapy until disease progression, unacceptable AEs or physician/patient decision. Eligible patients had measurable disease (serum M-protein >1 g/dL or urine M-protein ≥200 mg/24 h, or serum free light chain ≥10 mg/dL), prior exposure to ≥3 lines of anti-myeloma therapy or were double-refractory to immunomodulatory drugs (IMiDs) and proteasome inhibitors (PIs), prior treatment with an alkylating agent, and adequate baseline bone marrow reserve and organ function. Enrollment of 24 patients was planned for each treatment group. An interim efficacy analysis is planned when all patients have completed ≥2 disease assessments, with central review of these data currently ongoing. Enrollment has now been completed and all patients who completed at least 1 cycle of isatuximab at the cutoff date (5/29/15) are included in this preliminary analysis. Results: Patient characteristics (n=96): median age 62.5 yrs (range 38-85); median time from initial diagnosis to study treatment 5.85 yrs (1.2-24.1); 76% had IgA/G MM; 24% had light-chain only disease; and 22%, 22%, and 44% had Stage I, II, and III disease, respectively. The median number of prior lines of therapy was 5 (2-14) with 100%, 99%, and 98% having prior exposure to PIs, IMiDs, and alkylator-containing therapy, respectively. Overall, 78% of patients had previously received POM and/or CAR; 55% had been exposed to both of these agents. At data cut-off, 36.5% of patients remained on therapy and 53.1%, 6.3%, and 4.2% had discontinued therapy due to disease progression, AEs, or other reason, respectively. The median number of cycles received was 3 (1-9), with a median duration of treatment of 11.7 wks. Approximately 17% of patients required at least 1 dose delay and 7.3% of isatuximab infusions were interrupted. TEAEs occurred in 93% of patients, with 51% being grade ≥3. Drug-related TEAEs occurred in 61% of patients (grade ≥3, 10%). The most common drug-related TEAEs (>5% of patients) were nausea (14.6%), chills (14.6%), dyspnea (13.5%), chest discomfort (10.4%), flushing (7.3%), headache (7.3%), cough (6.3%), and vomiting (5.2%). The majority of the symptoms occurred within 24 h of isatuximab infusion and were attributed to an IAR. IARs occurred in 50% of patients, were predominantly grade 1/2 (grade ≥3, 3.1%), and were mostly limited to Cycle 1 (2 patients had IARs in Cycle 2). Pneumonia (6.3%) and sepsis (5.2%) were the most common serious TEAEs. Six deaths have occurred within 30 days of last dose, 4 due to disease progression, and 2 due to serious AEs unrelated to study therapy (cardiopulmonary arrest and cerebral hemorrhage). Conclusion: Isatuximab administered to heavily pre-treated patients with RRMM appears well tolerated. IARs are common in Cycle 1, but typically do not recur. Results by treatment arm, including interim analysis response data, will be presented. Disclosures Martin: Sanofi: Research Funding. Richter:Takeda: Speakers Bureau; Celgene: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Janssen: Speakers Bureau; Amgen: Speakers Bureau; Novartis: Speakers Bureau. Vij:Millennium: Honoraria, Speakers Bureau; Onyx: Consultancy, Honoraria, Research Funding, Speakers Bureau; Celgene: Consultancy, Honoraria, Research Funding, Speakers Bureau; BMS: Consultancy; Takeda: Consultancy, Research Funding; Novartis: Consultancy; Sanofi: Consultancy; Janssen: Consultancy; Merck: Consultancy. Zonder:Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS, Amgen, Prothena, Seattle Genetics: Membership on an entity's Board of Directors or advisory committees. Kaufman:Spectrum: Consultancy; Merck: Research Funding; Onyx: Consultancy, Research Funding; Novartis: Consultancy; Celgene: Consultancy, Research Funding; Millenium: Consultancy. Bensinger:Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; Acetylon: Research Funding; Sanofi: 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, Speakers Bureau; Onyx: Research Funding, Speakers Bureau; Millenium: Research Funding; BMS: Membership on an entity's Board of Directors or advisory committees, Research Funding. Dimopoulos:Novartis: Honoraria; Amgen: Honoraria; Genesis: Honoraria; Janssen: Honoraria; Celgene: Honoraria; Onyx: Honoraria; Janssen-Cilag: Honoraria. San Miguel:Millennium, Celgene, Novartis, Janssen, Onyx, BMS, MSD: Membership on an entity's Board of Directors or advisory committees. Zimmerman:Onyx: Honoraria; Celgene: Honoraria, Speakers Bureau; Millennium: Honoraria, Speakers Bureau; Amgen: Honoraria, Speakers Bureau. Hari:Celgene: Consultancy; Takeda: Consultancy; BMS: Consultancy; Janssen: Consultancy; Novartis: Consultancy; Spectrum: Consultancy; Sanofi: Consultancy. Gasparetto:Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Onyx: Honoraria; Millennium: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Kumar:Skyline, Noxxon: Honoraria; Celgene, Millennium, Onyx, Janssen, Noxxon, Sanofi, BMS, Skyline: Consultancy; Celgene, Millennium, Onyx, Novartis, Janssen, Sanofi: Research Funding. Hsu:Sanofi: Employment. Charpentier:Sanofi: Employment. Strickland:Alexion Pharmaceuticals: Other: Advisory Board Particpation; Amgen: Other: Advisory Board Particpation; Daiichi-Sankyo: Other: Advisory Board Particpation; Boehringer-Ingelheim: Other: Advisory Board Particpation; Sunesis Pharmaceuticals: Other: Steering Committee and Advisory Board Participation. Mikhael:Sanofi: Research Funding; Onyx: Research Funding; Celgene: Research Funding; AbbVie: Research Funding.

PURPOSE Observation is the current standard of care for smoldering multiple myeloma. We hypothesized that early intervention with lenalidomide could delay progression to symptomatic multiple myeloma. METHODS We conducted a randomized trial that assessed the efficacy of single-agent lenalidomide compared with observation in patients with intermediate- or high-risk smoldering multiple myeloma. Lenalidomide was administered orally at a dose of 25 mg on days 1 to 21 of a 28-day cycle. The primary end point was progression-free survival, with disease progression requiring the development of end-organ damage attributable to multiple myeloma and biochemical progression. RESULTS One hundred eighty-two patients were randomly assigned—92 patients to the lenalidomide arm and 90 to the observation arm. Median follow-up is 35 months. Response to therapy was observed in 50% (95% CI, 39% to 61%) of patients in the lenalidomide arm, with no responses in the observation arm. Progression-free survival was significantly longer with lenalidomide compared with observation (hazard ratio, 0.28; 95% CI, 0.12 to 0.62; P = .002). One-, 2-, and 3-year progression-free survival was 98%, 93%, and 91% for the lenalidomide arm versus 89%, 76%, and 66% for the observation arm, respectively. Only six deaths have been reported, two in the lenalidomide arm versus four in the observation arm (hazard ratio for death, 0.46; 95% CI, 0.08 to 2.53). Grade 3 or 4 nonhematologic adverse events occurred in 25 patients (28%) on lenalidomide. CONCLUSION Early intervention with lenalidomide in smoldering multiple myeloma significantly delays progression to symptomatic multiple myeloma and the development of end-organ damage.

Abstract Introduction: Venetoclax (Ven), an oral agent that targets the antiapoptotic protein, BCL-2, has demonstrated efficacy, as monotherapy and combined with proteasome inhibitor (PI) bortezomib, in relapsed/refractory (R/R) multiple myeloma (MM). We report preliminary safety and efficacy data for Ven combined with the second generation PI carfilzomib (K) and dexamethasone (VenKd) in R/R MM. Methods: In this ongoing phase 2, dose escalation study (NCT02899052), patients with R/R MM and no prior K exposure received VenKd on 28-d cycles in 4 dose finding and one expansion cohorts: Ven 400 mg/day + K 27 mg/m2 Day 1, 2, 8, 9, 15, 16 + dex 40 mg Day 1, 8, 15, 22 (Cohort 1), same regimen but with Ven 800 mg/day (Cohort 2), Ven 800 mg/day + K 70 mg/m2 Day 1, 8, 15 + dex 40 mg Day 1, 8, 15, 22 (Cohort 3/expansion cohort), or Ven 800 mg + K 56 mg/m2 Day 1, 2, 8, 9, 15, 16 + dex 40 mg Day 1, 2, 8, 9, 15, 16, 22, 23 (Cohort 4). Treatment continued until progressive disease (PD) or unacceptable toxicity. Results: As of June 11, 2018, 42 patients were enrolled. The median age was 66.5 years (min, max: 37, 79), 63% had ISS II/III disease, and 8 patients (19%) had t(11;14). Patients received a median of 2 prior therapies (range: 1 - 3), 93% had received prior PI (50% refractory), 62% were refractory to immunomodulatory therapies, and 33% double refractory. At the data cut off, 29 patients were still active and had completed ≥2 cycles and 13 patients discontinued with the primary reason being disease progression (n=4), death (n=3), physician decision (n=2), withdrawal of consent (n=2), lack of efficacy (n=1), and AE (n=1). All patients experienced at least one AE, and grade 3/4 AEs experienced by >10% of subjects included: decreased lymphocyte count (26%), decreased neutrophil count (14%), and hypertension (12%). Thirteen subjects experienced at least one serious AE. Maximum tolerated dose was not reached and Ven 800 mg/day + K 70 mg/m2 was selected for expansion. Ven mean (% coefficient of variation) maximum plasma concentration (Cmax) and area under the plasma concentration-time curve over 24 hours (AUC24) on Cycle 1 Day 15 were 2.7 (57) mg/mL and 33.1 (54) mg×h/mL, respectively, at 400 mg venetoclax (n=4); and were 2.42 (53) mg/mL and 38.7 (51) mg×h/mL, respectively, at 800 mg venetoclax (n=13) in the dose escalation cohorts. The overall response rate (ORR) was 78% and the very good partial response (VGPR) or better rate was 56% (Table). Median time from first dose to the data cut or discontinuation was 5.7 months (range: 0.9 - 16.3) and the median time to first response was 1.9 months (95% CI: 0.9, 9.2). ORRs for subgroups of interest are reported in the Table. Conclusions: The combination of VenKd appears tolerable with no new safety signals or changes in Ven pharmacokinetics. VenKd shows promising preliminary efficacy in R/R MM patient subgroups. Response rates were comparable in all high risk subgroups and overall population. However, the subset of patients with t(11;14) had the highest response. Overall, these results demonstrate that VenKd is a safe and efficacious regimen in R/R MM and support the continued study of VenKd. Disclosures Costa: Abbvie: Research Funding; BMS: Research Funding; Karyopharm: Research Funding; Amgen: Honoraria, Research Funding; Sanofi: Honoraria; Celgene: Honoraria, Research Funding; Janssen: Research Funding. Stadtmauer:Celgene: Consultancy; AbbVie, Inc: Research Funding; Janssen: Consultancy; Takeda: Consultancy; Amgen: Consultancy. Morgan:Bristol-Myers Squibb: Consultancy, Honoraria; Janssen: Research Funding; Takeda: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Research Funding. Kovacsovics:Amgen: Honoraria, Research Funding; Abbvie: Research Funding. Jakubowiak:Takeda: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Bristol-Myers Squibb: Consultancy, Honoraria; SkylineDx: Consultancy, Honoraria; Adaptive Biotechnologies: Consultancy, Honoraria; AbbVie: Consultancy, Honoraria; Karyopharm: Consultancy, Honoraria; Celgene: Consultancy, Honoraria. Kaufman:Roche: Consultancy; BMS: Consultancy; Karyopharm: Other: data monitoring committee; Janssen: Consultancy; Abbvie: Consultancy. Mobasher:Genentech Inc: Employment; F. Hoffmann-La Roche Ltd: Other: Ownership interests non-PLC. Freise:AbbVie, Inc: Employment, Equity Ownership. Ross:AbbVie, Inc: Employment, Equity Ownership. Pesko:AbbVie, Inc: Employment, Equity Ownership. Munasinghe:AbbVie, Inc: Employment, Equity Ownership. Gudipati:AbbVie, Inc: Employment, Equity Ownership. Mudd:AbbVie, Inc: Employment, Equity Ownership. Bueno:AbbVie, Inc: Employment, Equity Ownership. Kumar:Oncopeptides: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees; AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Research Funding; Merck: 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; Novartis: 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; 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; AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding.

Abstract Background: Maintenance therapy post-autologous stem cell transplantation (ASCT) has shown to improve progression-free and overall survival in multiple myeloma (MM) and has largely become the standard of care. Consolidation therapy, a brief duration of more-intensive chemotherapy administered prior to maintenance, has been shown to further deepen responses and may improve long-term outcomes. Ixazomib, lenalidomide and dexamethasone (IRd) is an all oral regimen that has been shown to be active in newly diagnosed MM as well as relapsed disease. In this study, we are analyzing the safety and efficacy of IRd as consolidation therapy after ASCT (NCT02253316). Methods: Eligible patients, age 18-70 with newly diagnosed MM undergoing ASCT during first-line treatment, are being consented prior to ASCT. Approximately 4 months following ASCT, patients receive 4 cycles of consolidation therapy with IRd [ixazomib 4 mg on days 1, 8 and 15 of a 28-day cycle, lenalidomide 15 mg on days 1 through 21, and dexamethasone 40 mg on days 1, 8 and 15]. The primary end point is minimal residual disease (MRD) status. MRD is being assessed by ClonoSEQ where possible and by multi-color flow where not. Toxicity, IMWG response rate, PFS, and OS are secondary end points. One month after the last consolidation cycle, patients are randomized (1:1) to maintenance therapy with single-agent ixazomib (4 mg on days 1, 8 and 15) or lenalidomide (15 mg daily). In total, 240 patients will be enrolled on the trial. This presentation coincides with planned interim analysis 2 which included data from the consolidation phase only. Results: As of July 2018, 172 patients with NDMM have been enrolled from 10 centers within the US. The median age was 57 (range 28-70) and 67% were male. 76% were white, 10% African-American/Black, and 13% were another race. 39% were ISS Stage I, 30% were Stage II, and 20% were Stage III. All patients received proteasome inhibitors and/or IMIDs as front-line induction and melphalan as conditioning for ASCT. IRd consolidation started at a median of 110 days post-ASCT (range 80-138). IRd has been well tolerated. Only 4% (6/154) of patients have been unable to complete the 4 cycles of consolidation to date due to toxicity. Grade 3 hematologic toxicity has been uncommon; 4% neutropenia, 3% thrombocytopenia, and 2% anemia. There has been no grade 4 hematologic toxicity. Non-hematologic grade 3-4 toxicities have included: infection (8%), nausea/vomiting/diarrhea (3%), and transaminitis (1%). No grade 3-4 peripheral neuropathy has been reported. One case of grade 5 pneumonia was reported but was not considered related to study treatment. Following ASCT, the MRD-negative rate was 26% and this improved to 37% following consolidation. In the subset of patients with Clonoseq results available, the MRD negative rate improved from 19% to 27%. Clinical response rate improved similarly; prior to consolidation the VGPR or better rate was 76% including 39% CR/sCR. Following consolidation, the VGPR or better rate was 85% including 56% CR/sCR. 137 patients went on to receive maintenance with either ixazomib (n = 71) or lenalidomide (n = 66). At time of submission, the median follow-up from start of IRd is 14 months and 28 patients have relapsed/progressed and 6 have expired. An interim analysis is planned for 2019, representing the first comparison of ixazomib and lenalidomide maintenance. Conclusion: IRd consolidation following ASCT appears to be safe and effective. The all oral regimen is convenient for patients which greatly simplifies follow-up in the peri-transplant period. Study enrollment is scheduled to complete in Q1 of 2019. Disclosures Vij: Karyopharma: 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; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; 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. Martin:Amgen: Research Funding; Sanofi: Research Funding; Roche: Consultancy. Deol:Kite Pharmaceuticals: Consultancy; Novartis: Consultancy. Kaufman:Janssen: Consultancy; Karyopharm: Other: data monitoring committee; BMS: Consultancy; Abbvie: Consultancy; Roche: Consultancy. Hofmeister:Oncopeptides: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Adaptive biotechnologies: 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; Bristol-Myers Squibb: Research Funding. Gregory:Poseida Therapeutics, Inc.: Research Funding. Berdeja:Amgen: Research Funding; Celgene: Research Funding; Janssen: Research Funding; Takeda: Research Funding; Poseida Therapeutics, Inc.: Research Funding; Bristol-Myers Squibb: Research Funding; Bluebird: Research Funding; Genentech: Research Funding; Glenmark: Research Funding; Novartis: Research Funding; Teva: Research Funding; Sanofi: Research Funding. Chari:Pharmacyclics: Research Funding; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Seattle Genetics: Membership on an entity's Board of Directors or advisory committees; Array Biopharma: Research Funding; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Adaptive Biotechnology: Membership on an entity's Board of Directors or advisory committees; Bristol Myers Squibb: Consultancy; The Binding Site: Consultancy.

Abstract Abstract 813FN2 Introduction: Carfilzomib is a next-generation proteasome inhibitor that selectively and irreversibly binds to its target, resulting in sustained inhibition absent of off-target effects relative to bortezomib. Carfilzomib has demonstrated durable anti-tumor activity and an acceptable tolerability profile in patients with multiple myeloma (MM). Final results will be presented for the bortezomib-naïve group of PX-171-004, a phase 2 study of single-agent carfilzomib in patients with relapsed and/or refractory MM. Herein we report the most recent data analysis available at time of abstract submission. Updated final results for the bortezomib-naïve group of PX-171-004, including OS data, will be presented at the meeting. Methods: Patients received either 20 mg/m2 for all treatment cycles (Cohort 1) or a stepped-up dose-escalating regimen of 20 mg/m2 for Cycle 1 and 27 mg/m2 for all treatment cycles thereafter (Cohort 2). Carfilzomib was administered over 2–10 minutes on Days 1, 2, 8, 9, 15, and 16 of every 28-day cycle, for a maximum of 12 cycles. The primary endpoint was the best overall response rate (ORR; [CR + VGPR + PR]) determined according to the IMWG Uniform Response Criteria. Secondary endpoints included the clinical benefit response rate (CBR; [ORR + MR per EBMT criteria]), progression-free survival (PFS), time to progression (TTP), duration of response (DOR), OS, and safety. The result of efficacy analysis from disease assessment by the Independent Review Committee is presented in this abstract. Results: 127 of 129 enrolled bortezomib-naïve patients were evaluable for response. Prior therapies included thalidomide (59%), lenalidomide (59%), alkylating agents (81%), and stem cell transplant (73%). Patients had received a median of 2 prior regimens (1 in 54 patients, 2 in 40 patients, 3 in 28 patients, and ≥4 in 7 patients). 84 patients (65%) were disease refractory to their most recent therapy, defined as ≤25% response or progression during or within 60 days after completion of therapy. The median duration of carfilzomib treatment is 7 cycles (range 1−12) in Cohort 1; 8 patients were receiving drug as of February 2011 in Cohort 2 with a median treatment of 6.5 cycles (range 1−13) at that time. Best ORR was 42% in Cohort 1 and 52% in Cohort 2. Median TTP was 8.3 months and median DOR was 13.1 months in Cohort 1. The median TTP and DOR for Cohort 2 have not been reached at the time of this interim analysis; the lower bound of the 95% CI for the median TTP was 10.2 months, and 84% were estimated to have DOR ≥1 year at the time of data cutoff. Higher response rates for Cohort 2 compared with Cohort 1 do not appear to be associated with higher toxicities. Patients with unfavorable cytogenetic characteristics (≥1 abnormality) per mSMART criteria had an ORR of 37% and CBR of 42% compared with 50% and 65%, respectively, for patients with no abnormality. The most common treatment-emergent adverse events (AEs), regardless of relationship to carfilzomib in Cohorts 1 and 2, respectively, were fatigue (71%, 54%), nausea (54%, 43%), anemia (46%, 37%), and dyspnea (49%, 33%). These were primarily ≤Grade 2 in severity. The most common Grade 3/4 AEs were anemia (15%), lymphopenia (15%), thrombocytopenia (13%), pneumonia (12%) and neutropenia (12%). Treatment-emergent peripheral neuropathy (PN) was mild and infrequent (16%). Only 1 case of Grade 3 PN (0.8%) was observed. Overall, 38 patients (30%) completed 12 cycles and 22 of these patients continued to receive carfilzomib therapy under a safety extension protocol (PX-171-010), an ongoing, multicenter, open-label phase 2 study to monitor long-term use of single-agent carfilzomib. Conclusions: To date we have seen robust and durable single-agent activity for carfilzomib in bortezomib-naïve patients with relapsed and often refractory MM with an ORR of 42−52% and a CBR of 59−63% from 2 separate dose cohorts in a population wherein 92% received an immunomodulatry drug and 73% had undergone an autologous stem cell transplant previously. These data are suggestive of a dose–response relationship and are being further evaluated in the exploratory phase 1b/2 study PX-171-007. Carfilzomib was associated with minimal PN and excellent long-term tolerability, with nearly one-third of patients completing 12 cycles and 22 of these continuing treatment beyond 1 year in the extension protocol PX-171-010. Disclosures: Vij: Onyx Pharmaceuticals: Consultancy, Research Funding; Celgene: Research Funding, Speakers Bureau; Millennium: Speakers Bureau. Kaufman:Millenium: Consultancy; Onyx Pharmaceuticals: Consultancy; Novartis: Consultancy; Keryx: Consultancy; Merck: Research Funding; Celgene: Research Funding. Jakubowiak:Ortho Biotech: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Celgene: Consultancy, Honoraria, Speakers Bureau; Millennium Pharmaceuticals, Inc.: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Onyx Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Exelixis: Consultancy, Honoraria. Wang:Onyx Pharmaceuticals: Research Funding. Jagannath:Millennium: Honoraria; Celgene: Honoraria; Onyx Pharmaceuticals: Honoraria; Merck: Honoraria; OrthoBiotec.Imedex: Membership on an entity's Board of Directors or advisory committees; Medicom World Wide: Membership on an entity's Board of Directors or advisory committees; Optum Health Education: Membership on an entity's Board of Directors or advisory committees; PER Group: Membership on an entity's Board of Directors or advisory committees. Kukreti:Celgene: Honoraria. Alsina:Millennium: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Allergan: Research Funding. Belch:Celgene: Research Funding; Onyx: Research Funding. Gabrail:Millennium: Research Funding. Matous:Celgene: Speakers Bureau; Millenium: Speakers Bureau; Cephalon: Speakers Bureau. Vesole:Celgene: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Millennium: Speakers Bureau. Orlowski:Onyx Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees. Kunkel:VLST biothech: Consultancy; Threshold: Consultancy; Onyx Pharmaceuticals: Consultancy. Wong:Onyx Pharmaceuticals: Employment, Equity Ownership. Stewart:Celgene: Consultancy, Research Funding; Millennium: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; BMS: Consultancy, Research Funding; Onyx Pharmaceuticals: Consultancy, Research Funding.

Abstract Abstract 1938 Background: Carfilzomib (CFZ), a selective, epoxyketone proteasome inhibitor, produces potent, sustained proteasome inhibition and lacks many of the off-target activities associated with bortezomib (BTZ). Durable single-agent activity with CFZ has been observed in patients (pts) with relapsed/refractory multiple myeloma (R/R MM) who have received multiple prior therapies as well as in pts with advanced stage disease or significant comorbidities (Jagannath et al. ASCO 2009 Meeting. Abstract 8504). PX-171-004, is an ongoing Phase 2 study of single-agent CFZ in pts with relapsed or refractory MM following 1–3 prior therapies. Here we present updated data on the BTZ-naïve pts and report on activity observed in pts with significant comorbidities or poor-risk cytogenetic or FISH markers for myeloma. Methods: Enrolled pts received either 20 mg/m2 for all treatment cycles, or a stepped-up, dose-escalating regimen of 20 mg/m2 for Cycle 1 and 27 mg/m2 for all treatment cycles thereafter. CFZ was administered on Days 1, 2, 8, 9, 15 and 16 every 28 days (one cycle), for a maximum of 12 cycles. Dexamethasone, 4mg, was administered prior to CFZ in Cycle 1 only. For the present analyses, pts were stratified according to several baseline criteria including ECOG performance score, cytogenetic or FISH markers of high-risk disease per mSMART criteria [del17p, t(4;14), t(14;16), del13 by karyotype and hypodiploidy] and serum ß2-microglobulin. The primary endpoint was overall response rate (ORR) per International Uniform Response Criteria for Multiple Myeloma. Results: Data are available for 110 BTZ-naïve pts. Baseline pt characteristics included: 60% of ECOG PS ≥1; 53% baseline neuropathy Grade 1/2; 30% moderately impaired renal function (CrCl <60 mL/min), and 17% diabetes. Approximately 13% of pts had cytogenetic or FISH markers of poor prognosis. The ORR for the entire BTZ-naïve population was 48%; the ORR for BTZ-naïve pts receiving 20–27 mg/m2 was 54%. The ORRs stratified according to dose and baseline measurements are detailed in the following table. The most common treatment-emergent AEs, regardless of relationship to study drug, were fatigue (61%), nausea (43%), anemia (39%), dyspnea (36%), cough (34%), headache (31%), thrombocytopenia and upper respiratory infections (30% each) and were primarily ≤ Grade 2 in severity. Grade 3/4 AEs occurring in >5% of pts included lymphopenia, neutropenia, pneumonia, thrombocytopenia, anemia and fatigue. Of note, there were no discontinuations for peripheral neuropathy and only 1 pt with impaired renal function at baseline was discontinued for creatinine increases. Twenty-four pts remain on study and 23% have completed the protocol-specified 12 cycles of therapy. Seventeen pts (20%) elected to continue CFZ on an extended treatment protocol (PX-171-010); no cumulative toxicities have been noted. Conclusions: Single-agent CFZ achieves high response rates in BTZ-naïve pts with relapsed myeloma, with minimal neuropathy, even in the setting of high-risk disease. In addition, single-agent CFZ continues to demonstrate long-term tolerability even in pts with comorbid conditions, including renal insufficiency and diabetes, who may benefit from a steroid-sparing treatment regimen. The data from this ongoing trial show that CFZ is a promising new treatment for multiple myeloma in the relapsed or refractory setting. Disclosures: Vij: Onyx: Honoraria. Kaufman:Celgene: Consultancy, Research Funding; Millenium: Consultancy; Merck: Research Funding. Jakubowiak:Millennium Pharmaceuticals, Inc.: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Honoraria; Centocor Ortho Biotec: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Exelixis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Jagannath:Millenium, OrthoBiotec, Celgene, Merck, Onyx: Honoraria; Imedex, Medicom World Wide, Optum Health Education, PER Group: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Kukreti:Celgene: Honoraria; Roche: Honoraria; Ortho Biotech: Honoraria. Alsina:Millenium: Consultancy, Research Funding; Celgene: Research Funding; Novartis: Consultancy. Gabrail:Millenium: Research Funding. Vesole:Celgene: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Millenium: Speakers Bureau. Le:Onyx Pharmaceuticals: Employment. Wang:Celgene: Research Funding; Onyx: Research Funding; Millenium: Research Funding; Novartis: Research Funding.

Abstract Background: The anti-apoptotic protein BCL-2 has been implicated in mediating the survival of multiple myeloma (MM) cells. Venetoclax is a potent, selective, orally bioavailable small-molecule BCL-2 inhibitor. Venetoclax induces cell death in MM cell lines in vitro and primary MM samples ex vivo. Certain genetic subtypes of MM cells are particularly sensitive to venetoclax, including t(11;14) cells, which express a high ratio of BCL2 to MCL1 (venetoclax resistance factor). The current Phase 1 study evaluates safety, efficacy, and pharmacokinetics (PK) in patients (pts) with relapsed/refractory MM. Methods: Primary objectives are to evaluate safety, PK, and recommended phase two dose; other objectives include assessing preliminary efficacy and the impact of chromosomal abnormalities. In dose-escalation (DE) cohorts, venetoclax was given orally daily at 300, 600, 900, or 1200 mg after a 2-week dose ramp-up (3+3 design). Patients in the safety expansion (SE) cohort received 1200 mg daily after ramp-up. All patients were monitored for tumor lysis syndrome (TLS). Results: As of June 17, 2015, 37 patients were enrolled in the study: 30 from DE cohorts and 7 from the SE. Median (range) age was 66 years; 19 (51%) were female. Fourteen were ISS stage I, 13 stage II, 8 stage III, 2 unknown. The median (range) number of prior lines of therapy was 6 (1-19). Thirty-two had prior bortezomib (20 refractory), 35 lenalidomide (18 refractory), and 26 had prior stem cell transplant. Fourteen patients had t(11;14), 4 had t(4;14), 5 had del 17p, and 17 had del 13q. Adverse events (AEs) in ≥20% of patients were nausea (49%), diarrhea (38%), vomiting (30%), anemia (27%), fatigue (24%). Grade 3/4 AEs (≥10%): thrombocytopenia (22%), anemia (19%), neutropenia (11 %). Serious AEs (≥2 patients): pyrexia (n=3), cough, malignant neoplasm progression, and sepsis (2 each); 2 (upper abdominal pain and anemia) were possibly related to venetoclax. Thirty (81%) patients have discontinued venetoclax: 24 due to PD, 3 for AEs (worsening shortness of breath, hypokalemia, and nausea), 2 withdrew consent, 1 due to death (brain hemorrhage following injury). Four deaths occurred (2 due to PD, 1 due to brain hemorrhage, 1 due to pneumopathy). Two of the 6 patients in the 600 mg cohort experienced DLTs of upper abdominal pain and nausea with abdominal pain. No patients met the criteria for laboratory or clinical TLS. Based on preliminary PK (n=21), the mean Cmax and AUC24 were ~dose-proportional at all studied doses (300, 600, 1200 mg) except 900 mg, and dose-normalized venetoclax exposure in MM was similar to that in CLL and NHL pts. Thirty-two of the 37 patients were evaluable for preliminary efficacy (Table). Two patients, both t(11;14), achieved a complete response (1 at 600 mg and 1 at 900 mg). Responses were first achieved at 1.8 and 1.1 months and were maintained for 9.7 and 9.0 months, respectively (900 mg pt remains in CR). Among the 16 patients receiving 1200 mg in the DE or SE cohort, 6 of whom had t(11;14), 5 achieved SD, 6 experienced PD, and 5 are not yet evaluable. Conclusions: Venetoclax monotherapy had a tolerable safety profile in heavily-pretreated relapsed/refractory MM, and no new safety signals were observed compared to other venetoclax studies. The study continues to enroll in the SE cohort at 1200 mg. Responses (including CR) and longer time on venetoclax were observed in t(11;14) patients. These early results suggest that venetoclax has single agent activity, most prominently in t(11;14) patients. Figure 1. Figure 1. Disclosures Kumar: Celgene: Research Funding; Millenium/Takeda: Research Funding; Onyx: Research Funding; AbbVie: Research Funding; Janssen: Research Funding; Sanofi: Research Funding; Celgene, Millenium, Sanofi, Skyline, BMS, Onyx, Noxxon,: Other: Consultant, no compensation,; Skyline, Noxxon: Honoraria. Off Label Use: Venetoclax is an investigational drug that is not yet approved in this indication.. Vij:Takeda, Onyx: Research Funding; Celgene, Onyx, Takeda, Novartis, BMS, Sanofi, Janssen, Merck: Consultancy. Kaufman:Janssen: Consultancy; Spectrum: Consultancy; Merck: Research Funding; Celgene: Consultancy; Onyx: Consultancy; Novartis: Consultancy; Novartis: Research Funding; Onyx: Research Funding. Mikhael:Sanofi: Research Funding; AbbVie: Research Funding; Celgene: Research Funding; Onyx: Research Funding. Moreau:Takeda: Other: Adboard; Janssen: Other: Adboard; Celgene: Other: Adboard; Novartis: Other: Adboard; Amgen: Other: Adboard. Alzate:AbbVie: Employment, Equity Ownership. Morris:AbbVie: Employment, Equity Ownership. Ross:AbbVie: Employment, Equity Ownership. Dunbar:AbbVie: Employment, Equity Ownership. Zhu:AbbVie: Employment, Equity Ownership. Maciag:AbbVie: Employment, Equity Ownership. Agarwal:AbbVie: Employment, Equity Ownership. Leverson:AbbVie: Employment, Equity Ownership. Enschede:AbbVie: Employment, Equity Ownership. Humerickhouse:AbbVie: Employment, Equity Ownership. Touzeau:AbbVie: Research Funding.