Citations

Abstract Background: Treatment of multiple myeloma has evolved considerably in the past few years with availability of several news drugs as well as increasing use of multidrug combinations. These changes have no doubt led to the improved survival seen among patients with MM. We have previously shown that outcomes of patients intolerant or refractory to one of the IMiDs and bortezomib had a poor outcome. Since that time, other drugs of the same class as well as new classes of drugs have been introduced for the treatment of MM. We designed this retrospective study to estimate the outcomes in patients with relapsed myeloma, who have become refractory to the current generation IMiDs and proteasome inhibitors. Patients and Methods: Patients with relapsed multiple myeloma who have received at least 3 prior lines of therapy, is refractory to both an IMiD (lenalidomide or pomalidomide) AND a proteasome inhibitor (bortezomib or carfilzomib), and has been exposed to an alkylating agent were identified from multiple centers. The time patients met the above criteria was defined as T0, and details of all treatment regimens before and after T0 were collected using electronic CRFs. The study was approved by the IRB at the respective centers. Results: 543 patients were enrolled in this study; median age was 62 years (31-87) and 61% were males. Patients were enrolled from centers in North America (n=181), Europe (n=318), and Asia Pacific (n=44). Patients were diagnosed between 2006 and 2014, the median duration between diagnosis of myeloma and study entry (T0) was 3.1 years (0.3 to 9). The median (95% CI) estimated follow up from diagnosis and from T0 were 61 (57, 66) months and 13 (11, 15) months respectively. The median number of lines of therapy prior to T0 was 4 (3-13), 48% had a prior transplant. The median OS from T0 for the entire cohort was 13 (11, 15) months. For these 462 patients, the median number of recorded regimens was 2 (1-9). The overall response and the depth of response to each line of treatment following T0 are as shown in the table. The median (95% CI) PFS and OS from T0 was 5 (4, 6), and 15.2 (13, 17), respectively. The overall survival for the 81 patients with no treatment post T0 was only 2.1 months. In a multivariate analysis, duration from diagnosis to T0, ISS stage III and number of lines of therapy were all associated with inferior PFS, as well as OS, and in addition, serum creatinine>2 mg/dL at T0 also predicted inferior OS. Conclusions: The study provides the expected outcome following development of myeloma that is refractory to a PI and an IMiD. The outcomes of these patients appear to be better than we had seen historically in patients refractory/ intolerant to bortezomib and IMiDs, highlighting the increased treatment options available for these patients. However, there is decreasing response rate to sequential regimens highlighting the development of drug resistance. The data provides a bench mark for comparison of new therapies that are being evaluated in this disease. Table Table. Disclosures Dimopoulos: Janssen: 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; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Genesis: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Kastritis:Takeda: Consultancy, Honoraria; Genesis: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Amgen: Consultancy, Honoraria. Terpos:BMS: Consultancy, Honoraria; Janssen: Consultancy, Honoraria, Other: Travel expenses, Research Funding; Celgene: Honoraria; Takeda: Consultancy, Honoraria; Genesis: Consultancy, Honoraria, Other: Travel expenses; Amgen: Consultancy, Honoraria, Other: Travel expenses, Research Funding; Novartis: Honoraria. Hillengass:Sanofi: Research Funding; Novartis: Research Funding; Amgen: Consultancy, Honoraria; BMS: Honoraria; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria. Leleu:TEVA: Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria; LeoPharma: Honoraria; Amgen: Honoraria; Bristol-Myers Squibb: Honoraria; Pierre Fabre: Honoraria; Celgene: Honoraria; Novartis: Honoraria; Takeda: Honoraria. Oriol:Janssen: Honoraria, Other: Expert board committee; Amgen: Honoraria, Other: Expert board committee. Cavo:Celgene: Consultancy, Honoraria; Millennium: Consultancy, Honoraria; Bristol-Myers Squibb: Consultancy, Honoraria; Janssen-Cilag: Consultancy, Honoraria; Amgen: Consultancy, Honoraria. Mateos: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, Membership on an entity's Board of Directors or advisory committees; 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. Vij:Shire: Consultancy; Takeda: Consultancy, Research Funding; Jazz: Consultancy; Karyopharma: Consultancy; Janssen: Consultancy; Novartis: Consultancy; Celgene: Consultancy; Bristol-Myers Squibb: Consultancy; Amgen: Consultancy, Research Funding. Lokhorst:Genmab: Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding. van de Donk:Amgen: Research Funding; Janssen: Research Funding; BMS: Research Funding; Celgene: Research Funding. Mark:Onyx: Research Funding, Speakers Bureau; Millenium: 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, Research Funding, Speakers Bureau. Ludwig:Amgen: Research Funding, Speakers Bureau; Takeda: Research Funding, Speakers Bureau; BMS: Speakers Bureau; Janssen: Speakers Bureau. Jagannath:Novartis: Consultancy; Janssen: Consultancy; Bristol-Myers Squibb: Consultancy; Celgene: Consultancy; Merck: Consultancy. Usmani:Array: Research Funding; Britsol-Myers Squibb: Consultancy, Research Funding; Skyline: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; BioPharma: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Onyx: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharmacyclics: Research Funding; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Sanofi: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Amgen: Consultancy, Research Funding, Speakers Bureau; Millenium: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Speakers Bureau. Dytfeld:Janssen Poland: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Research Funding; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees. Moreau:Novartis: Honoraria; Amgen: Honoraria; Celgene: Honoraria; Bristol-Myers Squibb: Honoraria; Takeda: Honoraria; Janssen: Honoraria, Speakers Bureau. Lee:Amgen: Membership on an entity's Board of Directors or advisory committees. Shustik:Janssen: 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; Millenium: 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; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees. de la Rubia:Celgene: Consultancy; Bristol Myers: Consultancy; Amgen,: Consultancy; Janssen: Consultancy. Durie:Takeda: Consultancy; Amgen: Consultancy; Janssen: Consultancy.

Abstract Background: p38a mitogen-activated protein kinase (MAPK) mediates production of proinflammatory cytokines and other factors including PGE-2 induced RANKL and IL-1 induced IL-6. SCIO-469 inhibits p38a MAPK blocking synthesis of Il-1ß, PGE2, VEGF, MIP-1α and TNFα thus reducing in vitro MM tumor growth and survival, and drug resistance. Objectives: Assess efficacy, safety, tolerability of SCIO-469 as M or MB in patients (pts) with relapsed and refractory multiple myeloma. Methods: Pts were treated with SCIO-469 alone (60 mg po tid)and assessed on Days 15, 30, 52 and 73. Bortezomib (1.0–1.3mg/m2 d 1,4,8,11 q21d) was added to M for PD or SD. Pts who had clinical benefit on either M or MB at Day 73 were allowed to continue on extension study for up to a total of 168 d, to further evaluate efficacy and saftey of M or MB. Results: 62 pts were enrolled: 39 M, 23 F, median age was 63 years (range 48–84), D-S stage at Dx: I (6%), II (32), III (60%%); median time from diagnosis to treatment 3.1 years; median # prior Rx = 5; including 29% with > 6; 71% prior transplant. 27 had received prior bortezomib and 17 were considered refractory. All 62 pts received study drug; 34 pts received MB at some time during the treatment period. 5 of the 28 (18%) pts treated with M and 25 of 34 (74%) pts treated with MB continued on the extension study. Median time on study was 77.5 d (range 7–304) for M and 180.5 d (range 34–275) for MB. Best response (EBMT; Blade 1998) to M was stable disease in 24% of pts; the best response to MB was 9/34 PR (26%), 2/34 MR (6%),3/34 SD (9%). Median time to progression (TTP) was 50 days for M compared to 140 days for MB. Safety/Tolerability: Adverse events on M were tabulated separately from those on MB. Neutropenia was minimal, < 3% with either regimen; anemia (47 vs 29%) and thrombocytopenia (26 vs 16%) were more prevalent with MB vs M, respectively. Epistaxis, fatigue and diarrhea were seen in > 15% of pts receiving M. Nausea, vomiting, diarrhea, constipation, abdominal pain, fatigue, pyrexia, anorexia, URI, arthralgia, muscle cramp, dizziness, peripheral neuropathy and headache occurred in > 15% pts receiving MB. 10 pts died on study, 9 during primary phase and 1 during extension phase. 3 deaths were the result of sepsis, the remaining 7 were due to progressive disease. Conclusions: SCIO-469, 60 mg tid, as monotherapy or in combination with Bortezomib was well tolerated. Although there were no objective responses in M (compared to 32% (11/34) in MB-including 4 patients who had failed prior bortezomib), 24% had stable disease at the end of monotherapy. Further studies to refine the dose of SCIO-469 as monotherapy and of SCIO-469 in combination with other agents are warranted.

Abstract Background: BT062 (Biotest AG, Dreieich, Germany) is an antibody-drug conjugate (ADC) comprising a CD138-binding chimerized antibody and the cytotoxic maytansinoid, DM4. It is designed to target and kill CD138-positive cancer cells. CD138 (Syndecan-1) is highly expressed on a number of solid tumors and hematological malignancies and is one of the most reliable markers for multiple myeloma (MM) cells. BT062 was previously evaluated as a monotherapy in patients with heavily pretreated relapsed/refractory MM and found to have an acceptable tolerability profile with preliminary evidence of activity (Heffner et al, Blood. 2012; 120: Abstract 4042). Phase I/IIa testing was initiated with BT062 in combination with lenalidomide (Len) and low-dose dexamethasone (dex). The combination was well tolerated at BT062 doses up to 100 mg/m², defined to be the recommended Phase 2 dose (RPTD), and induced meaningful responses, including in patients previously treated with both Len and bortezomib (Bort) (Kelly et al, Blood. 2014; 124: Abstract 4736). Based on these promising results, further investigation of BT062 in combination with pomalidomide (Pom) and dex was initiated in patients with prior Len and Bort exposure, a patient population known to have a poor outcome. Objectives: To evaluate the safety and activity of BT062 (on days 1, 8, and 15 in a 4-week cycle) used in combination with dex (20-40 mg on days 1, 8, 15, and 22) and Len (25 mg, daily on days 1-21) or Pom (4 mg, daily on days 1-21) in patients with relapsed/refractory MM. Methods: This is a prospective, open label, multicenter Phase I/IIa study. The RPTD of BT062 in combination with Len/dex was defined to be 100 mg/m², and 38 patients were treated with BT062/Len/dex at the BT062 RPTD. An additional 17 patients were treated with BT062/Pom/dex at the BT062 RPTD. Patients aged ≥18 years with relapsed/refractory MM were eligible to participate. Prior treatment with Len, Pom, and/or dexamethasone (any dose) was allowed. To qualify for treatment with BT062/Len/dex at the BT062 RPTD, patients must have received at least one but no more than six prior therapies.To qualify for treatment with BT062/Pom/dex, patients must have received at least two prior therapies, including both Len and Bort, and progressed on or within 60 days of completion of their last therapy, with no limit on number of prior therapies. Patients with clinical response (or no evidence of disease progression) without unacceptable toxicities were eligible to receive additional treatment cycles. Toxicities were assessed by CTCAE v4. Clinical response was assessed by the investigator according to International Myeloma Working Group criteria. Results: Sixty-four patients have received BT062 in combination with dex and Len or Pom in this ongoing study. The combinations have been generally well tolerated, with approximately 90% of adverse events (AEs) reported CTC grade 1 or 2. The most common AEs reported are diarrhea, fatigue, and nausea. Forty-seven patients have received BT062 with Len/Dex (3 at 80 mg/m², 38 at 100 mg/m², 6 at 120 mg/m²), with 8 patients still on treatment. Among these 47 patients, median progression-free survival (PFS) was 16.4 months. Forty-three patients completed at least two treatment cycles and were evaluable for response. Of these patients 33 achieved a partial response (PR) or better, with an overall response rate (ORR) of 77% and a median duration of response (DOR) of 21.0 months. Thirteen of the evaluable BT062/Len/dex-treated patients had prior exposure to both Len and Bort and progressed on or within 60 days of their last therapy. ORR was 54% among these patients, including 1 complete response (CR), 4 very good partial responses (VGPR) and 2 PRs. Seventeen patients were treated with BT062/Pom/dex, all had prior exposure to both Len and Bort and progressed on or within 60 days of their last therapy. ORR was 79%, with 4 VGPR and 7 PR among the 14 patients evaluable for efficacy. Median PFS has not been reached after 7.5 months median follow up, with 7 patients still on treatment. Updated safety and activity data will be presented. Conclusion: BT062 has been found to be well tolerated when used in combination with Len/dex or Pom/dex, with encouraging activity even in patients with Len- and Bort-pretreated disease progressing on or within 60 days of completion of their last therapy. Disclosures Kelly: Novartis: Consultancy, Speakers Bureau; Pharmacyclics: Consultancy, Speakers Bureau; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees. Siegel:Novartis: Honoraria, Speakers Bureau; Takeda: Honoraria, Speakers Bureau; Amgen: Honoraria, Speakers Bureau; BMS: Honoraria, Speakers Bureau; Celgene: Honoraria, Speakers Bureau; Merck: Honoraria. Somlo:Millennium: Speakers Bureau; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding. Heffner:Millennium: Research Funding; AbbVie: Research Funding; Pharmacyclics: Research Funding; Celgene: Research Funding. Madan:Onyx: Speakers Bureau; Amgen: Speakers Bureau; Takeda: Speakers Bureau; Celgene: Speakers Bureau. Lonial:Celgene: Consultancy; Celgene: Consultancy; BMS: Consultancy; Onyx: Consultancy; Millenium: Consultancy; Novartis: Consultancy; Janssen: Consultancy; Novartis: Consultancy; Onyx: Consultancy; Janssen: Consultancy; Merck: Consultancy; BMS: Consultancy. Barmaki-Rad:Biotest AG: Employment. Rühle:Biotest AG: Employment. Herrmann:Biotest AG: Employment. Wartenberg-Demand:Biotest AG: Employment. Haeder:Biotest AG: Employment. Anderson:Celgene: Membership on an entity's Board of Directors or advisory committees; Oncoprep: Equity Ownership; Acetylon: Equity Ownership; Acetylon: Equity Ownership; Gilead: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Oncoprep: Equity Ownership; Millennuim: Membership on an entity's Board of Directors or advisory committees; Millennuim: Membership on an entity's Board of Directors or advisory committees; C4 Therapeutics: Equity Ownership; C4 Therapeutics: Equity Ownership; Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees; Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees.

Abstract Background: Oprozomib (OPZ) is an oral epoxyketone proteasome inhibitor that selectively and irreversibly binds to its target. Preliminary findings of OPZ in pts with hematologic malignancies (HM) have been reported previously (Savona, ASH 2012, 203; Kaufman, EHA 2013, P223; Ghobrial, ASH 2013, 3184). Updated safety and efficacy results from the subset of pts with MM enrolled in this ongoing phase 1b/2 study in pts with HM are presented. Methods: This open-label, phase 1b/2 study (NCT01416428) is enrolling adult pts with HM who have relapsed after receiving ≥1 line of therapy. The primary objectives (phase 1b portion) are to determine the maximum tolerated dose (MTD) and the safety and tolerability profile of OPZ. The primary objective (phase 2 portion) is to determine the best overall response rate (ORR; ≥PR). In the phase 1b portion, OPZ is being administered once daily on days 1, 2, 8, and 9 of a 14-day cycle (2/7 schedule) or on days 1–5 of a 14-day cycle (5/14 schedule). The starting dose was 150 mg/day (mg/d); doses were escalated in 30-mg increments up to 330 mg/d. In the phase 2 portion, pts are receiving OPZ (240 mg/d) on the 5/14 schedule (initial phase 2 schedule opened to enrollment). For this report, all enrolled patients with HM are included in the description of the MTD while only the subset of patients with WM is included in the safety and efficacy results. Results: As of July 21, 2014, 106 pts with HM (including 68 pts with MM) were enrolled and treated with the OPZ tablet. Enrollment and baseline demographic information for pts with MM are presented in Table 1. Median treatment duration (phase 1b) was 21.3 weeks (range, 0.3–62.1; 2/7 schedule) and 10.1 weeks (range, 0.3–81.1; 5/14 schedule); preliminary median treatment duration in the ongoing phase 2 portion was 5.4 weeks (range, 0.7–26.7). In all patients with HM, the MTD for the 2/7 schedule was 300 mg/d and 240 mg/d for the 5/14 schedule. Of 3 dose-limiting toxicities (DLTs) on the 2/7 schedule, all 3 DLTs (including hypotension [300 mg/d, n=1], grade 3 diarrhea and grade 4 thrombocytopenia [330 mg/d, n=1 each]) were observed in pts with MM. Of 4 DLTs on the 5/14 schedule, 2 DLTs (grade 3 renal failure [180 mg/d, n=1] and grade 3 tumor lysis syndrome [270 mg/d, n=1]) were observed in pts with MM. The most common adverse events (AEs) in patients with MM are shown in Table 2. Grade 4 AEs included 8 pts (11.8%) with thrombocytopenia, 4 pts (5.9%) with anemia, and 1 pt each (1.5%) with sepsis, leukopenia, decreased platelet count, hyperkalemia, and acute renal failure. Two pts died from upper gastrointestinal bleeding (5/14 schedule, 240 mg/d). One pt (5%) on the 2/7 schedule (phase 1b), 3 pts (15%) on the 5/14 schedule (phase 1b), and 8 pts (30%) on the 5/14 schedule (phase 2) discontinued treatment due to an AE; 6 pts (29%) on the 2/7 schedule (phase 1b), 7 pts (35%) on the 5/14 schedule (phase 1b), and 11 pts (41%) on the 5/14 schedule (phase 2) had their dosage reduced at least once due to an AE. Thirty-four pts in the phase 1b portion were eligible for response. In the phase 1b portion, the ORR in 15 pts on the 2/7 schedule (all were carfilzomib [CFZ]-naïve) was 33.3%; the clinical benefit rate (CBR) was 46.7% (3 very good partial response [VGPR], 2 partial response [PR], and 2 minimal response [MR]). Among 19 pts on the 5/14 schedule (phase 1b portion; all were CFZ-naïve), the ORR was 36.8%; the CBR was 42.1% (1 complete response, 2 VGPR, 4 PR, and 1 MR). In the 5/14 schedule (phase 1b), the ORR among bortezomib [BTZ]-refractory pts (n=7) was 14.3%. On the phase 2 portion (5/14 schedule), the ORR among CFZ-refractory pts (n=11) and CFZ-sensitive pts (n=12) was 27.3% (3 PR) and 33.3% (2 VGPR and 2 PR), respectively; the ORR among BTZ-refractory pts (n=12) was 25.0%. Conclusions: The MTD of OPZ was 300 mg/d in the 2/7 schedule and 240 mg/d in the 5/14 schedule; these MTDs were determined from all patients with HM. The most common grade 3 AEs were diarrhea, nausea, and vomiting; grade 4 AEs were infrequent. Additional measures will be taken to improve gastrointestinal tolerability. Single-agent OPZ continues to have promising antitumor activity. Enrollment of pts with MM is continuing on the phase 2 study in both treatment schedules. Extended-release OPZ tablets will be introduced and assessed for safety, activity, and pharmacokinetics. Updated results will be presented at the meeting. Figure 1 Figure 1. Figure 2 Figure 2. Disclosures Vij: Celgene: Honoraria, Research Funding; Onyx: Honoraria, Research Funding; Sanofi: Honoraria; Jannsen: Honoraria; Novartis: Honoraria; Millennium: Honoraria; Array: Honoraria. Off Label Use: Carfilzomib as treatment in multiple myeloma and solid tumors. Savona:Incyte: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Karyopharm: Consultancy, Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees. Siegel:Celgene: Honoraria, Speakers Bureau; Onyx: Honoraria, Speakers Bureau; Millennium: Honoraria, Speakers Bureau. Kaufman:Millennium: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Onyx: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Honoraria; Spectrum: Consultancy, Honoraria; Merck: Research Funding. Ghobrial:BMS: Advisory Board Other; Celgene: Advisory Board, Advisory Board Other; Millennium: Advisory Board, Advisory Board Other; Onyx: Advisory Board, Advisory Board Other. Paner:Celgene Corporation: Honoraria. Jagannath:Millenium: Honoraria; Celgene: Honoraria; Onyx: Honoraria; Merck: Honoraria; Ortho: Membership on an entity's Board of Directors or advisory committees; im: Membership on an entity's Board of Directors or advisory committees; Medicom Worldwide: Membership on an entity's Board of Directors or advisory committees; Optum Health Worldwide: Membership on an entity's Board of Directors or advisory committees; PER group: Membership on an entity's Board of Directors or advisory committees. Jakubowiak:BMS: Advisory Board Other, Consultancy, Honoraria; Celgene: Advisory Board, Speaking, Advisory Board, Speaking Other, Consultancy, Honoraria; Janssen: Advisory Board, Speaking, Advisory Board, Speaking Other, Consultancy, Honoraria; Millennium: Advisory Board, Advisory Board Other, Consultancy, Honoraria; Novartis: Advisory Board Other, Honoraria; Onyx: Advisory Board, Speaking Other, Consultancy, Honoraria; Skyline Dx: Advisory Board Other, Honoraria. Mikhael:Onyx: Research Funding; Celgene: Research Funding; Sanofi: Research Funding; Novartis: Research Funding. Kapoor:Onyx: Membership on an entity's Board of Directors or advisory committees, Research Funding. Neuman:Onyx: Employment. Lee:Onyx Pharmaceuticals, an Amgen subsidiary: Employment.

Abstract Introduction - With over 12,000 deaths from MM anticipated in 2016, nearly all patients (pts) with multiple myeloma (MM) will become "quad refractory" to IMIDs (lenalidomide and pomalidomide) and proteasome inhibitors (bortezomib and carfilzomib), and eventually "penta refractory" to anti-CD38 Abs (daratumumab and isatuximab), defining high unmet need populations. Selinexor, an oral selective XPO1 inhibitor, induces nuclear accumulation and activation of tumor suppressor proteins, inhibition of NF-kB, and inhibition of translation of several oncoprotein mRNAs such as c-myc and cyclin D. Selinexor showed potent induction of apoptosis of MM cells independent of p53 signaling. In phase 1 clinical studies, selinexor with low dose dexamethasone (Sd) demonstrated potent anti MM activity in pts with MM. Methods - This phase II clinical trial evaluated Sd in pts with MM refractory to bortezomib, carfilzomib, lenalidomide, and pomalidomide ("quad"), with a subset also refractory to an anti-CD38 Ab ("penta"). Inclusion required CrCL≥20 mL/min, ANC≥1000/µL, platelets ≥50K/µL (≥30K if plasma cells were ≥50% of marrow cellularity). Pts were treated twice weekly (BIW) with oral selinexor 80 mg for 6 or 8 doses per 28 day cycle and dexamethasone (dex) 20 mg BIW. All pts received 5-HT3 antagonists. The primary objective was to determine the overall response rate (ORR) per IMWG criteria and duration of response (DOR), both adjudicated by an independent review committee (IRC). Secondary endpoints include progression free survival (PFS) and overall survival (OS). FISH analyses and gene expression profiling were performed on bone marrow aspirates. Results - 79 pts were enrolled: 48 quad (24 M/24 F, median age 62 yrs) and 31 penta (13 M / 18 F, median age 68 yrs). Both groups had a median of 7 prior treatment regimens including multiple dex-containing regimens. Baseline laboratory abnormalities included grade (Gr)≥3 anemia in 13% and Gr≥3 thrombocytopenia in 8%. Most penta pts received 8 doses / cycle (65%); most quad pts received 6 doses / cycle (83%). Common treatment-related adverse events (TRAEs) hematological: thrombocytopenia (72%, Gr 3/4 58%), anemia (48%, Gr 3 25%) and neutropenia (29%, Gr≥3 21%). TRAEs non-hematological: nausea (72%, Gr 3 6%), fatigue (62%, Gr 3 14%) anorexia (49%, Gr 3 3%), vomiting (43%, Gr3 4%), asymptomatic hyponatremia (42%. Gr 3 20%), diarrhea (42%, Gr 3 5%) and weight loss (33%, Gr 3 1%). There was one case of febrile neutropenia (1%) and one case of clinically significant bleeding related to thrombocytopenia (1%). Seventy pts have discontinued therapy: PD (73%), AEs (17%), physician/pt preference (1%) and 6 deaths (one case related to selinexor, intracranial bleed in pt with Gr4 thrombocytopenia). Nine pts remain on study. Efficacy was evaluated in 78 pts (1 pt did not have measurable disease). The IRC-determined ORR (≥PR) for all pts was 21%, including 5% VGPR. ORR was 21% for quad pts and 20% for penta pts. Clinical benefit rates (≥MR) were 32% (all), 29% (quad), and 37% (penta). Median OS was 9.3 months (mo) for all pts, >11 mo (median not reached) for responders (≥PR), and 5.7 mo for non-responders. Median DOR in responding pts was 5 mo, and median PFS in all pts was 2.1 mo. Baseline cytogenetics were assessed in 41 pts. The ORR in 18 pts with high-risk FISH abnormalities was 33% (Table 1). Notably, 3 of the 13 pts with a 17p abnormality responded (ORR 23%). Transcriptomic profiling revealed differentially expressed genes (DEGs) between responders and non-responders in both whole blood RNA and CD138+ bone marrow cells. Pathways enriched in responders included IL-6, IL-8 and IGF-1 pathways. Conclusions - Oral Sd is active in heavily pretreated pts with refractory MM, including those with MM refractory to anti-CD38 Ab and those with high-risk cytogenetic abnormalities. Response was associated with longer survival. The main toxicities of Sd are thrombocytopenia, nausea, anorexia, and fatigue. AEs were manageable with supportive care and dose interruptions/reductions. To our knowledge, this is the first report of anti-tumor activity in the penta-refractory MM population. This population of MM pts has exhausted all currently available treatment options and has an extremely poor prognosis and therefore requires new therapies. Expansion of this trial in this high unmet medical need, penta refractory population is planned. Table 1 Activity of Sd in Patients with High Risk MM Cytogenetics Table 1. Activity of Sd in Patients with High Risk MM Cytogenetics Disclosures Vogl: Constellation: Research Funding; Karyopharm: Consultancy; Acetylon: Research Funding; GSK: Research Funding; Calithera: Research Funding; Teva: Consultancy; Celgene: Consultancy; Takeda: Consultancy, Research Funding. Jagannath:Bristol-Myers Squibb: Consultancy; Janssen: Consultancy; Novartis: Consultancy; Merck: Consultancy; Celgene: Consultancy. Baz:Bristol-Myers Squibb: Research Funding; Takeda/Millennium: Research Funding; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Signal Genetics: Research Funding; Novartis: Research Funding; Karyopharm: Research Funding; Merck: Research Funding. Nooka:Spectrum, Novartis, Onyx pharmaceuticals: Consultancy. Richter:Takeda: Consultancy, Speakers Bureau; Amgen: Consultancy, Speakers Bureau; Celgene: Consultancy, Speakers Bureau; Janssen: Speakers Bureau; Bristol-Myers Squibb: Speakers Bureau; Novartis: Speakers Bureau. Vij:Karyopharm: Honoraria; Amgen: Honoraria, Research Funding; Celgene: Consultancy; Takeda: Honoraria, Research Funding; Novartis: Honoraria; Bristol-Myers Squibb: Honoraria; Janssen: Honoraria. Schiller:Incyte Corporation: Research Funding. Costa:Sanofi: Honoraria, Research Funding. Chari:Array Biopharma: Consultancy, Research Funding; Takeda: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Pharmacyclics: Research Funding; Janssen: Consultancy, Research Funding; Amgen Inc.: Honoraria, Research Funding; Novartis: Consultancy, Research Funding. Siegel:Takeda: Honoraria, Speakers Bureau; Novartis: Honoraria, Speakers Bureau; Amgen: Honoraria, Speakers Bureau; Celgene: Honoraria, Speakers Bureau; BMS: Honoraria, Speakers Bureau; Merck: Honoraria. Fonseca:Janssen: Consultancy; AMGEN: Consultancy; Millennium, a Takeda Company: Consultancy; Bayer: Consultancy; Sanofi: Consultancy; Patent Pending: Patents & Royalties: The use of calcium isotopes as biomarkers for bone metabolisms; Patent: Patents & Royalties: Prognostication of MM based on genetic categorization of FISH of the disease; AMGEN: Consultancy; Novartis: Consultancy; Millennium, a Takeda Company: Consultancy; Sanofi: Consultancy; AMGEN: Consultancy; Janssen: Consultancy; BMS: Consultancy; Celgene: Consultancy; BMS: Consultancy; Millennium, a Takeda Company: Consultancy; Millennium, a Takeda Company: Consultancy; Patent: Patents & Royalties: Prognostication of MM based on genetic categorization of FISH of the disease; Bayer: Consultancy; Novartis: Consultancy; Patent Pending: Patents & Royalties: The use of calcium isotopes as biomarkers for bone metabolisms; AMGEN: Consultancy; Patent: Patents & Royalties: Prognostication of MM based on genetic categorization of FISH of the disease; Patent: Patents & Royalties: Prognostication of MM based on genetic categorization of FISH of the disease; Patent Pending: Patents & Royalties: The use of calcium isotopes as biomarkers for bone metabolisms; Patent Pending: Patents & Royalties: The use of calcium isotopes as biomarkers for bone metabolisms; Celgene: Consultancy. Kauffman:Karyopharm Therapeutics Inc: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees. Shacham:Karyopharm Therapeutics: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees. Saint-Martin:Karyopharm: Employment. Picklesimer:Karyopharm: Employment. Friedlander:Karyopharm Therapeutics: Employment. Choe-Juliak:Karyopharm Therapeutics: Employment.

Abstract Background: BT062 (Biotest AG Dreieich, Germany) is an antibody-drug conjugate (ADC), comprising the anti-CD138 chimerized MAb (nBT062) and the maytansinoid DM4 as a cytotoxic agent. It is designed to bind to CD138 on cancer cells, and then release DM4 after internalization to cause cell death. CD138 (Syndecan-1) is highly overexpressed on various solid tumors and in hematological malignancies, and represents one of the most specific target antigens for identification of multiple myeloma (MM) cells. BT062 was investigated as a single agent and found to have an acceptable tolerability profile and evidence of activity in patients with heavily pretreated relapsed and/or refractory MM (1). Preclinical studies showed enhanced anti-MM activity when BT062 was combined with lenalidomide and dexamethasone (Len/Dex). Based on these data, a Phase I/IIa study in MM was initiated to evaluate the safety and efficacy of BT062 in combination with Len/Dex. Objectives: To determine the dose-limiting toxicities (DLTs), the maximum tolerated dose (MTD), the recommended phase II dose (RPTD), pharmacokinetics (PK), and anti-MM activity of increasing doses of BT062 (days 1, 8, and 15, every 4 weeks) used in combination with Len (25 mg, daily on days 1-21) and low dose Dex (40 mg on days 1, 8, 15, and 22) in patients with relapsed and/or refractory MM. Methods: This is a prospective, open label, multicenter Phase I/IIa study. The Phase I part includes dose escalation, and the Phase IIa the expansion of the RPTD cohort. Patients aged ≥18 years with relapsed and/or refractory MM who have failed at least one prior therapy were eligible to participate. Prior treatment with Len and/or Dex was allowed. Patients with clinical response (or no evidence of progressive disease) and without unacceptable toxicities were eligible for additional treatment cycles. Patients were enrolled in cohorts of at least 3 at each dose level; DLT in the first cycle triggered cohort expansion. Toxicities were assessed by CTCAE v4 and clinical response was assessed according to International Myeloma Working Group criteria. Results: The maximum administered dose (MAD) was 120 mg/m². Two of six patients treated at this dose had a DLT: mucosal inflammation (CTC grade 3) and anemia (CTC grade 3). The MTD was defined as 100 mg/m² and selected as RPTD. Additional patients are being treated at this RPTD to further evaluate safety and efficacy. Enrollment into the study is ongoing. As of July 2014, a total of 45 patients had received BT062 at dose levels of 80 mg/m² (N=3), 100 mg/m² (N=36) or 120 mg/m² (N=6). Fifteen patients discontinued study treatment: 5 for disease progression, 7 for adverse events, 1 died (not treatment related) and 2 for withdrawal of consent. The other 30 patients remain on treatment. The median treatment duration was 123 days (range 1–597). The median number of prior therapies was 3 (range 1–11). 68% of patients had prior exposure to both Len and bortezomib, 73% of patients had prior Len exposure, and 30% were Len-refractory. According to preliminary data from this ongoing study, about 89% of reported Adverse Events (AEs) were CTC grade 1 or 2. The most common reported AEs were diarrhea, fatigue, nausea, and hypokalemia. Amongst the 36 patients across all dose levels currently evaluable for efficacy, the overall response rate (ORR) is 78%; including 1 stringent complete response, 2 complete responses, 10 very good partial responses, and 15 partial responses. Two patients achieved a minor response and 6 patients disease stabilization, resulting in a clinical benefit in 100% of the evaluable patients. The ORR was 83% among the 30 evaluable patients receiving the RPTD. Interestingly, the ORR was 70% among the 23 patients with prior exposure to Len and bortezomib, and among 10 patients refractory to prior treatment with Len. Conclusion: Preliminary data from this ongoing study indicate that BT062 is well tolerated in combination with Len/Dex at dose levels that induce responses in patients with relapsed and/or refractory multiple myeloma, including patients with prior exposure to both Len and bortezomib and patients refractory to prior treatment with Len. Updated results on safety and efficacy will be presented. References Heffner et al, BT062, an Antibody-Drug Conjugate Directed Against CD138, Given Weekly for 3 Weeks in Each 4 Week Cycle: Safety and Further Evidence of Clinical Activity. Blood. 2012; 120: Abstract 4042. Disclosures Kelly: Celgene: Speakers Bureau. Heffner:Amgen: Honoraria, Research Funding; Biotest: Research Funding; Dana Farber CI: Research Funding; Genentech: Research Funding; Gilead: Research Funding; Idera: Research Funding; Janssen: Research Funding; Pfizer: Research Funding; Pharmacyclics: Honoraria, Research Funding; Onyx: Research Funding; Spectrum: Research Funding; Talon Therapeutics: Research Funding. Somlo:Millennium: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees. Siegel:Celgene: Honoraria, Speakers Bureau; Onyx: Honoraria, Speakers Bureau; Millennium: Honoraria, Speakers Bureau. Munshi:Celgene: Consultancy; Onyx: Consultancy; Janssen: Consultancy; Sanofi-Aventis: Consultancy; Ocopep: Consultancy, Equity Ownership, Patents & Royalties. Jagannath:Celgene: Consultancy; Millennium: Consultancy; Sanofi: Consultancy. Lonial:Millennium: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; BMS: Consultancy, Research Funding; Onyx: Consultancy, Research Funding. Ailawadhi:Millennium: Consultancy, Honoraria. Barmaki-Rad:Biotest AG: Employment. Chavan:Biotest Pharmaceuticals: Employment. Patel:Biotest Pharmaceuticals: Employment. Wartenberg-Demand:Biotest AG: Employment. Haeder:Biotest AG: Employment. Anderson:Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Millennium: Consultancy, Membership on an entity's Board of Directors or advisory committees; Onyx: Consultancy, Membership on an entity's Board of Directors or advisory committees; Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees; Sanofi Aventis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Oncopep: Equity Ownership; Acetylon: Equity Ownership.

Abstract Abstract 1845 Poster Board I-871 Background: Proteasome inhibition is an effective strategy for the treatment of multiple myeloma. In patients, proteasome inhibition has primarily been measured in peripheral blood samples (whole blood or mononuclear cells). However, it is unknown whether myeloma cells in the bone marrow (BM) are equally sensitive to proteasome inhibitors such as bortezomib (BTZ) and carfilzomib (CFZ). Aim: To measure proteasome inhibition in purified tumor cells from BM samples taken from patients enrolled in two ongoing Phase 2 trials of single agent CFZ in relapsed or refractory myeloma: PX-171-003 (003) and PX-171-004 (004). Methods: CFZ was administered as an IV bolus of 20 mg/m2 on Days 1, 2, 8, 9, 15 and 16 of a 28-day cycle on both trials. Bone marrow samples, from an optional sub-study of both trials, were taken during screening and Day 2 (post-treatment) and sorted into CD138+ and CD138− cells. Proteasome activity was measured by an enzymatic assay using a fluorogenic substrate (LLVY-AMC) for the chymotrypsin-like (CT-L) activity and an active site ELISA (ProCISE) to quantitate levels of the CT-L subunits of the constitutive proteasome (Beta5) and immunoproteasome (LMP7) and the immunoproteasome subunit MECL1. Results: Whole blood samples from patients treated with CFZ showed inhibition of CT-L activity of ∼80+, similar to values obtained in Phase 1 studies. A total of 10 CD138+ screening samples, 6 from 004 and 4 from 003, and 9 post-dose samples, 5 from 004 and 4 from 003, were analyzed for proteasome levels and activity. In addition, 15 CD138−screening samples, 7 from 004 and 8 from 003, and 9 post-dose samples, 5 from 004 and 4 from 003, were analyzed. When compared to the average base-line activity, CFZ treatment resulted in 88% CT-L inhibition in CD-138+tumor cells from 004 patients (P = 0.0212 by unpaired t-test) and 59% CT-L inhibition in CD-138+ tumor cells from 003 patients (P = 0.25). Baseline CT-L activity in CD138+ tumor cells was 3-fold higher in 004 than 003, which includes a more heavily pre-treated patient population with greater prior exposure to BTZ. Higher specific enzymatic activity was due to increased levels of both constitutive and immunoproteasomes in tumor cells, where immunoproteasomes account for >75% of total cellular proteasomes. No differences between trials were seen in baseline CT-L activity from non-tumor (CD138−) cells. Inhibition in CD138− cells was 84% (P = 0.0380 and 42% (P = 0.38) in 004 and 003, respectively. Using ProCISE, we measured inhibition of LMP7 (66%), beta5 (48%) and MECL1 (64%) in CD138+ tumor cells from 004 patients. Three patients from 004 and one from 003 had both a screening and post-dose tumor cell samples available for analysis. Inhibition of CT-L activity was >80% in two of the 3 patients on 004; the third patient showed no proteasome inhibition by ProCISE and was unavailable for analysis by CT-L. CT-L activity in the CD138+ tumor cells in the 003 patient was not inhibited, however, inhibition was seen in non-tumor cells. Conclusions: CFZ inhibits the proteasome activity of myeloma cells in the bone marrow of relapsed and refractory myeloma patients. The levels of inhibition were similar to those measured in whole blood samples, supporting the use of the blood-based assay as a surrogate marker for proteasome inhibition in tumor cells. CFZ treatment resulted in inhibition of both CT-L subunits as well as additional subunits of the immunoproteasome in tumor cells. Reduced baseline activity in the more heavily pretreated 003 patients may reflect reduced tumor-dependency on the proteasome and may be related to prior treatment with BTZ in these patients. More samples are needed in order to make correlations between levels of proteasome inhibition in bone marrow tumor cells and prior therapies or response. These observations support further evaluation of proteasome activity and the effects of this promising new agent in primary tumors cells from myeloma patients. Disclosures: Trudel: Celgene: Honoraria, Speakers Bureau; Ortho Biotech: Honoraria. Lee:Proteolix, Inc.: Employment. Kirk:Proteolix, Inc.: Employment. Lonial:Celgene: Consultancy; Millennium: Consultancy, Research Funding; BMS: Consultancy; Novartis: Consultancy; Gloucester: Research Funding. Wang:Proteolix, Inc.: Research Funding. Kukreti:Celgene: Honoraria. Stewart:Genzyme, Celgene, Millenium, Proteolix: Honoraria; Takeda, Millenium: Research Funding; Takeda-Millenium, Celgene, Novartis, Amgen: Consultancy. Jagannath:Millennium: Honoraria, Membership on an entity's Board of Directors or advisory committees; Merck: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees. McDonagh:Proteolix: Research Funding. Zonder:Celgene: Speakers Bureau; Pfizer: Consultancy; Seattle Genetics, Inc.: Research Funding; Amgen: Consultancy; Millennium: Research Funding. Bennett:Proteolix: Employment.

Abstract Abstract 1827 Poster Board I-853 Background It is now well established that cytogenetic abnormalities can affect the responses to therapies in multiple myeloma (MM) patients. Bortezomib, used alone or in combination with other agents, has been shown to overcome the adverse impact of several common unfavorable cytogenetic features. More recently, responses with lenalidomide and dexamethasone have been reported in patients with some types of unfavorable cytogenetics. Carfilzomib (CFZ) is a novel proteasome inhibitor that has demonstrated single agent activity in relapsed and/or refractory MM patients. The objective of this analysis was to provide the first preliminary information on the influence of cytogenetics in patients (pts) with relapsed and/or refractory MM treated with CFZ. Methods We evaluated 79 pts treated on two single agent CFZ studies (PX-171-003 and PX-171-004) in relapsed and/or refractory myeloma in which metaphase cytogenetics and/or FISH analysis for del 13q, t(4:14), and t(14;16) chromosomal abnormalities were available. Metaphase cytogenetics was conducted for all pts in the analysis; fluorescence in situ hybridization (FISH) results were available for 28 of the 79 pts. Twenty-one pts with relapsed and refratory MM (PX-171-003) and 58 pts with relapsed or refractory MM (PX-171-004) received CFZ at 20 mg/m2 IV on days 1, 2, 8, 9, 15, and 16 in a 28-day cycle for up to 12 cycles. For this analysis, responders were defined as pts who achieved at least a Minor Response (MR) [MR + Partial Response (PR) + Very Good Partial Response (VGPR) + Complete Response (CR)] by IMWG and EBMT criteria. Results The median age of analysed pts was 63 yrs and 100% of pts were relapsed, with 70% refractory to their last therapy. Analysis of their histories demonstrated prior thalidomide treatment in 75% of pts, prior lenalidomide treatment in 57%, prior bortezomib treatment in 55%, and prior stem cell transplantation in 84%. The response rate (≥MR) for the entire group of patients was 40.5%. Twenty three of 79 pts had at least one of the abnormalities. The presence of del 13q, t(4;14), or t(14;16) did not significantly change the response rates, with 43.5% of pts with one or more abnormalities responding compared to 39.3% with none. The median time to progression (TTP) for all patients in this analysis was 203 days. The TTP for pts with one or more of the abnormalities was 195 days and was not significantly different from the TTP of 208 days for pts with none of the abnormalities (Figure; P > 0.05). Conclusion In this preliminary analysis, CFZ showed comparable activity in relapsed and relapsed/refractory MM with del 13q and/or t(4:14), and/or t(14;16) versus none of these abnormalities, with ≥MR in 43.5% vs. 39.3% of patients, and a TTP of 195 vs. 208 days, respectively. Updated efficacy data and TTP data will be presented at the meeting. Disclosures Jakubowiak: Millennium: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Centocor Ortho Biotech: 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. Wang:Proteolix, Inc.: Research Funding. Jagannath:Millennium: Honoraria, Membership on an entity's Board of Directors or advisory committees; Merck: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees. Siegel:Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Millennium: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Stewart:Takeda-Millenium, Celgene, Novartis, Amgen: Consultancy; Takeda, Millenium: Research Funding; Genzyme, Celgene, Millenium, Proteolix: Honoraria. Kukreti:Celgene: Honoraria. Lonial:Celgene: Consultancy; Millennium: Consultancy, Research Funding; BMS: Consultancy; Novartis: Consultancy; Gloucester: Research Funding. McDonagh:Proteolix: Research Funding. Vallone:Proteolix, Inc.: Employment. Kauffman:Proteolix, Inc.: Employment. Vij:Proteolix: Research Funding.

3010 Background: To test the safety and efficacy of the CAR T cell modality in relapsed/refractory multiple myeloma (MM), we have designed a second-generation CAR construct targeting B cell maturation antigen (BCMA) to redirect T cells to MM. bb2121 consists of autologous T cells transduced with a lentiviral vector encoding a novel CAR incorporating an anti-BCMA scFv, a 4-1BB costimulatory motif and a CD3-zeta T cell activation domain. We will report updated safety and efficacy following initial results (Berdeja et al, ENA 2016). Methods: CRB-401 (NCT02658929) is a multi-center phase 1 dose escalation trial of bb2121 in patients with relapsed and/or refractory MM who have received ≥ 3 prior regimens, including a proteasome inhibitor and an immunomodulatory agent, or are double-refractory, and have ≥ 50% BCMA expression on plasma cells. Peripheral blood mononuclear cells are collected via leukapheresis. Patients undergo lymphodepletion with Flu (30 mg/m 2 ) / Cy (300 mg/m 2 ) daily for 3 days then receive 1 infusion of bb2121. The study follows a standard 3+3 design with planned dose levels of 5, 15, 45, 80 and 120 x 10 7 CAR+ T cells. Results: As of November 18, 2016, 11 patients had been infused with bb2121 in the first 4 dose cohorts, and 9 patients had reached at least 1 month of follow-up. As of data cut-off, no dose-limiting toxicities and no > Grade 2 neurotoxicities or cytokine release syndrome (CRS) had been observed. Grade 1-2 CRS had been reported in 8/11 (73%) treated patients. All patients treated with doses of 15.0 x 10 7 or higher remained on study and the overall response rate (ORR) in the 6 evaluable patients at these doses was 100%, including 2 sCRs and 2 MRD-negative responses (1 sC, 1 VGPR). CAR+ T cell expansion has been demonstrated consistently. An additional 6 months of follow up on previously reported results and initial data from an additional ~10 patients will be presented. Conclusions: bb2121 shows promising efficacy at dose levels above 5 x 10 7 CAR+ T cells, including 2 sCRs and ongoing clinical responses at 6 months, with mild and manageable CRS to date. These initial data support the potential of CAR T therapy with bb2121 as a new treatment paradigm in MM. Study sponsored by bluebird bio. Clinical trial information: NCT02658929.