Orlowski, Robert Z.

Abstract Abstract 1875 Introduction: Carfilzomib (CFZ) is a next-generation proteasome inhibitor that has demonstrated durable single-agent antitumor activity in patients (pts) with relapsed and/or refractory multiple myeloma (R/R MM). Previously we have shown that unfavorable cytogenetic features, defined as presence of any of del 13 or hypodiploidy by metaphase cytogenetic analysis and/or del 17p13, t(4;14), t (14;16) by fluorescence in situ hybridization (FISH), did not appreciably affect overall (≥PR) and clinical benefit (≥MR) response rates (ORR and CBR) in PX-171-003-A1, a large phase 2 study of single-agent CFZ in pts with R/R MM (Jakubowiak et al. Ann Oncol. 2011;22(S4): Abstract 117). The objectives of the present analysis were to evaluate the impact of specific cytogenetic abnormalities on efficacy and treatment outcomes. Methods: Pts with unfavorable cytogenetic abnormalities (defined above) were eligible for inclusion in this analysis. All pts received CFZ at 20 mg/m2 IV on days 1, 2, 8, 9, 15, and 16 of 28-day cycles (C) and were dose-escalated to 27 mg/m2 at C2. Pts were treated for up to 12 C. Responses were assessed by International Myeloma Working Group criteria, with minimal response (MR) by European Group for Blood and Marrow Transplantation criteria. Assessments were confirmed by an Independent Review Committee (IRC). Results: A total of 234 pts were included in this analysis. Metaphase cytogenetic data were available for 203 pts (87%), and FISH data were available for 210 pts (90%); 178 pts had both (76%). Seventy-five of 234 pts (32%) had ≥1 abnormality and represented the unfavorable group in this analysis. Of these, 49 (65%) had abnormalities detected via metaphase cytogenetics, 47 (63%) by FISH, and 21 (28%) by both methods. Characteristics of pts in the unfavorable and normal/favorable groups were comparable overall, with the exception of a higher proportion of pts with International Staging System stage II/III in the unfavorable group (83% vs 64%). Response rates per the IRC, presented previously, included an ORR of 30% for pts with ≥1 abnormality compared with 23% for pts with none. The corresponding CBRs were 34% and 40%, respectively. Duration of response (DOR) and time to progression (TTP) values were 7 months (mo) (95% CI 4–9) and 4 mo (95% CI 3–6), respectively, for pts with ≥1 abnormality and 8 mo (95% CI 6–12) and 5 mo (95% CI 3–6), respectively, for pts with none. The ORRs, CBRs, and disease control rates (DCRs) according to specific cytogenetic abnormalities are presented below. Response rates were largely unaffected by the presence of specific unfavorable cytogenetic abnormalities, with the possible exceptions of trends toward a higher response rate for t(4;14) and a lower rate for t(14;16), although the latter abnormality was only noted in 3 pts. The trend for better response rates in pts with t(4;14) corresponded to a DOR of 5.6 mo (95% CI 2.8–10.2). In contrast, the DOR appeared shorter for the subgroup of pts with del 17p13 (4.6 mo, 95% CI: 3.7–Not reached). Time-to-event endpoints including TTP are being analyzed for these and the other subpopulations, and data on these will be presented, along with overall survival stratified by cytogenetic abnormality. Conclusions: CFZ demonstrated comparable response rates in pts with relapsed/refractory MM in both the absence and presence of unfavorable cytogenetic abnormalities in the 003-A1 study. Similarly, in the phase 2 PX-171-004 study, no significant difference in response rates between unfavorable and normal/favorable groups has been observed in a population of less heavily-pretreated pts with relapsed or R/R MM. Taken together, the results of these and other analyses to date suggest that responses to single-agent CFZ can be achieved in heavily pretreated pts and that overall, these responses appear not to be significantly influenced by poor prognostic cytogenetic features. Further analyses from studies with CFZ in newly diagnosed MM and in less heavily-pretreated pts are needed to determine whether a trend toward lower response rates and DOR for pts with del 17p13 is consistently observed in other populations. Disclosures: 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. Off Label Use: Use of the investigational agent carfilzomib, proteasome inhibitor, in the treatment of relapsed and/or refractory multiple myeloma. Siegel: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. Singhal:Celgene: Speakers Bureau; Millennium: Speakers Bureau; Onyx Pharmaceuticals: Research Funding. Martin:Celgene: Honoraria; Onyx Pharmaceuticals: Consultancy. Lonial:Onyx: Consultancy; Bristol-Myers Squibb: Consultancy; Novartis: Consultancy; Celgene: Consultancy; Millennium Pharmaceuticals, Inc.: Consultancy; Merck: Consultancy. Kukreti:Celgene: Honoraria. Bahlis:Celgene: Honoraria, Speakers Bureau. 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. Kunkel:Onyx Pharmaceuticals: Consultancy; Threshold: Consultancy; VLST biothech: Consultancy. Wong:Onyx Pharmaceuticals: Employment, Equity Ownership. Orlowski:Onyx Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees. Stewart:Celgene Corporation: Consultancy, Research Funding; Millenium: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; BMS: Consultancy, Research Funding; Onyx: Consultancy, 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. Wang:Onyx Pharmaceuticals: Research Funding.

Abstract Abstract 985 Introduction: CFZ is a novel and highly selective epoxyketone proteasome inhibitor currently in clinical development for the treatment of multiple myeloma (MM). Ph 1 and 2 studies with CFZ have demonstrated durable single-agent antitumor activity in pts with relapsed or refractory (R/R) MM. The present study, PX-171-003-A1, was an open-label, single-arm Ph 2b trial and enrolled patients with multiply relapsed MM whose disease was refractory (defined as <25% response on, or progression during or <60 days after completion of, therapy) to their last treatment regimen. Patients must have received ≥2 prior therapies including: 1) bortezomib (BTZ) and either thalidomide (THAL) or lenalidomide (LEN), and 2) an alkylating agent. Materials and Methods: Pts received CFZ at 20 mg/m2 on a QDx2 schedule (Days 1, 2, 8, 9, 15, and 16 every 28 days) in cycle (C) 1 and were dose escalated to 27 mg/m2 on the same schedule thereafter for up to 12 C. Pts completing 12 C were eligible to enter an extension study (PX-171-010). The primary endpoint was overall response rate (ORR) (≥ partial response [PR]). Secondary endpoints included: clinical benefit response (CBR) (ORR + Minimal response [MR]), duration of response for ≥PR (DOR), overall survival (OS), time to progression (TTP), progression free survival (PFS), and safety. Responses and progression were determined according to the International Myeloma Working Group (IMWG) criteria and were assessed and confirmed by an Independent Response Committee (IRC). Results: 266 pts were enrolled with a median duration of MM of 5.4 years including 83% whose disease had progressed on or within 60 d of last therapy and 17% whose disease had achieved <25 % response to the regimen immediately preceding study entry. Of the 266 pts enrolled pts, 257 were evaluable for response; 9 patients were considered not evaluable based on missing baseline or lacking at least one post-baseline M-protein. An ORR (≥PR) of 24% with a median DOR of 7.4 mo (range 6.2–10.3) was determined. Responses are detailed in the table. The CBR (ORR + MR) was 36%. Median DOR of pts with MRs was 6.3 months, indicating that long-term MRs were observed. An additional 32% (83 pts) achieved SD for at least 6 wks. To date, 79 pts (30%) completed ≥6 C and >11% of pts have completed all 12 C of protocol specified therapy and most have entered the extension protocol; 15 pts remain on study (all >10 C). OS and TTP data for the overall population will also be reported. The enrolled pts in this study were heavily pretreated having received a median of 5 prior lines of therapy (range 1–20, median of 13 anti-myeloma agents). 85% of pts had received at least 2 and 37% had received at least 3 drugs in the regimen just prior to entering the study. Prior anti-myeloma agents included 99.6% (265/266 pts) BTZ (median 2 prior regimens containing BTZ), 99.6% either THAL (74%) or LEN (94%), 98% corticosteroids, 91% alkylating agents, and 74% stem cell transplant; 65% of pts were refractory to BTZ at any point in time prior to study entry. The most common treatment-emergent adverse events ≥ Grade (G) 3 regardless of relationship to study drug were predominantly hematologic and included thrombocytopenia (22%), anemia (20%), lymphopenia (10%), pneumonia (8%), neutropenia (8%), fatigue (7%), hyponatremia (5%), and hypercalcemia (5%). Although 206 pts (77%) had G1/2 peripheral neuropathy (PN) at baseline, new onset PN was infrequent and G ≥3 PN occurred in <1%. Interestingly, in this subset of patients, efficacy response was nearly identical to that seen in the full study population with an ORR (≥PR) of 24%. Conclusions: Single-agent CFZ achieved durable responses in pts with R/R MM whose disease had relapsed after all available therapies including BTZ and immunomodulatory agents. The CBR and median DOR achieved with this steroid-sparing regimen establish that CFZ has the potential to offer substantial clinical benefit to patients with relapsed or refractory disease. CFZ was well-tolerated and side effects were clinically manageable with no new or unexpected toxicities observed. Importantly, exacerbation of pre-existing PN was uncommon. Cumulative side effects were not observed, allowing prolonged single-agent dosing for chronic disease control. Disclosures: Siegel: Millenium: Consultancy, Honoraria; Celgene: Consultancy, Honoraria. Martin:Celgene: Honoraria; Onyx: Consultancy. Wang:Celgene: Research Funding; Onyx: Research Funding; Millenium: Research Funding; Novartis: Research Funding. Vij:Onyx: Honoraria. Jakubowiak:Millennium Pharmaceuticals, Inc.: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Honoraria; 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. 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. Lonial:Millennium: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; BMS: Consultancy, Research Funding; Onyx: Consultancy, Research Funding. Kukreti:Celgene: Honoraria; Roche: Honoraria; Ortho Biotech: Honoraria. Alsina:Millenium: Consultancy, Research Funding; Celgene: Research Funding; Novartis: Consultancy. Zonder:Millenium: Consultancy, Honoraria, Research Funding; Cephalon: Research Funding; Celgene: Honoraria. Wong:Onyx Pharmaceuticals: Employment. Vallone:Onyx Pharmaceuticals: Employment. Chang:Onyx Pharmaceuticals: Employment. Kauffman:Onyx Pharmaceuticals: Employment. Stewart:Millennium: Consultancy; Celgene: Honoraria. Singhal:Celgene: Speakers Bureau; Takeda/Millenium: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Onyx : Research Funding.

Abstract Abstract 1876 Carfilzomib (CFZ), 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, is being evaluated in MM patients. The selectivity of CFZ for the proteasome may explain the low rates of peripheral neuropathy (PN) relative to historical data for bortezomib (BTZ). Safety data have been compiled for >700 patients who received CFZ in 9 Phase (Ph) 1 or 2 trials, 4 of which are completed. The majority of patients had relapsed and refractory (R/R) MM, and many had comorbidities including baseline PN and renal insufficiency. This abstract updates and summarizes mature safety data for single-agent CFZ in 526 patients with R/R MM who took part in 1 of 3 Ph 2 studies and is a follow-up with more mature data compared with those presented at ASH 2010. Patients enrolled and treated with CFZ in the following trials are included in this analysis: PX-171-003 (conducted in 2 parts, a pilot study, PX-171-003-A0 [R/R MM], followed by PX-171-003-A1 [R/R MM]), PX-171-004 (relapsed MM), and PX-171-005 (R/R MM with varying degrees of renal function). In all studies, CFZ was dosed on Days 1, 2, 8, 9, 15, and 16 of a 28-day cycle (C). Doses were 20 mg/m2 in C1, escalating to 27 mg/m2 in C2 for all studies with the exception of 005 (15 mg/m2 in C1, 20 mg/m2 in C2, and 27 mg/m2 in C3). Overall, CFZ had a favorable safety profile in these studies. The most frequently reported adverse events (AEs) occurring in ≥30% of patients included fatigue (55%), anemia (47%), nausea (45%), thrombocytopenia (36%), dyspnea (35%), diarrhea (33%), and pyrexia (30%). The most common (≥10% of patients overall) ≥G3 AEs were thrombocytopenia (23%), anemia (22%), lymphopenia (18%), pneumonia (11%), and neutropenia (10%). The assessment of PN was based on a pooled aggregate of PN preferred terms, including neuropathy peripheral, neuropathy, peripheral sensory neuropathy, and peripheral motor neuropathy. PN was reported infrequently (14% overall) across all studies. Although 378 (72%) patients had baseline PN (≤G 2), only 13% reported treatment-emergent symptoms during the study. PN was generally mild to moderate in severity (1.3% G3 PN with no G4 PN), and only 5 patients (1%) required dose modification or discontinuation due to PN. Renal AEs (mainly ≤G2) were reported in 174 (33%) patients, and CFZ was discontinued because of a renal AE in only 21 patients (4%). A summary of CFZ exposure and discontinuation rates is reported in the table. There were a total of 37 (7%) deaths on study, including within 30 days of the last dose of study drug. The primary cause of death was due to disease progression in 22/37 patients (4.2%); however, AEs, including in order of frequency, cardiac events, hepatic failure, and infection, contributed to 14 of these deaths.No. of Patients (%) in Ph 2 MM Studies Who Received Carfilzomib003-A0 (N = 46)003-A1 (N = 266)004 (N = 164)005 (N = 50)All Patients (N = 526)Cycles, mean, n (SD)4.4 (3.4)5.3 (4.1)7.0 (4.4)5.5 (3.7)5.7 (4.2)Completed ≥12 cycles4 (8.7)40 (15.0)47 (28.7)3 (6.0)94 (17.9)Reason for not completing 12 cycles Progressive Disease23 (50.0)157 (59.0)64 (39.0)24 (48.0)268 (51.0) Adverse Event13 (28.3)33 (12.4)26 (15.9)6 (12.0)78 (14.8) Withdrew Consent2 (4.3)22 (8.3)9 (5.5)4 (8.0)37 (7.0) Other4 (8.7)14 (5.3)10 (6.1)028 (5.3) Of the 526 patients included in these analyses, >50% were treated on the 003-A1 dose and schedule (20/27 mg/m2), and fewer than 10% required dose reduction. 18% of patients completed ≥12 cycles (∼1 y) and were eligible to participate in an ongoing, multicenter, open-label Ph 2 study (PX-171-010) to monitor long-term single-agent CFZ safety. To date, patients in this extension trial have not shown evidence of cumulative toxicity. In summary, these data confirm and extend results that were previously presented, namely that single-agent CFZ has an acceptable safety profile in heavily pretreated patients with R/R MM, including those with pre-existing renal dysfunction and PN. Disclosures: Singhal: Onyx Pharmaceuticals: Research Funding, Speakers Bureau; Millennium: Speakers Bureau; Celgene: Speakers Bureau. Siegel: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. Martin:Celgene: Honoraria; Onyx Pharmaceuticals: Consultancy. Vij:Onyx Pharmaceuticals: Consultancy, Research Funding; Celgene: Research Funding, Speakers Bureau; Millennium: Speakers Bureau. Wang:Onyx Pharmaceuticals: Research Funding. Jakubowiak:Ortho Biotech: Consultancy, Honoraria, Speakers Bureau; Celgene: Consultancy, Honoraria, Speakers Bureau; Millennium: 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. Lonial:Millennium: Consultancy; Celgene: Consultancy; Novartis: Consultancy; BMS: Consultancy; Onyx Pharmaceuticals: Consultancy; Merck: Consultancy. Kukreti:Celgene: Honoraria. Zonder:Millennium: Consultancy, Research Funding, Speakers Bureau; Celgene: Speakers Bureau; Medtronics: Honoraria; Amgen: Consultancy. Wong:Onyx Pharmaceuticals: Employment, Equity Ownership. McCulloch:Onyx Pharmaceuticals: Employment. Niesvizky:Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Millennium Pharmaceuticals, Inc.: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Onyx: Research Funding; Seattle Genetics Inc: Research Funding, Speakers Bureau. Orlowski:Onyx Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees. Stewart:Celgene: Consultancy, Research Funding; Millennium: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; BMS: Consultancy, Research Funding; Onyx: Consultancy, Research Funding. Kotlovker:Onyx Pharmaceuticals: Employment. 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.

Abstract Abstract 3989 Background: Treatment patterns of multiple myeloma (MM) vary across the globe, mostly dictated by the availability and patient access to different drug therapies. The outcomes of patients with MM, especially relapsed myeloma can be significantly affected by the availability of newer treatments, as well as potential biological differences related to ethnicity. We have previously shown that the outcome of patients relapsing after therapy with bortezomib (Bz) and one or more of the IMiDs remain poor with the currently available treatments and represent a difficult group of patients to treat. We undertook the current analysis on a set of patients from United States, several European countries and South Korea. Methods: We designed a multicenter, retrospective study that enrolled 294 patients with relapsed MM, from 14 sites (122 from Europe, 107 from US, and 65 from Korea). Patients were refractory to Bz, defined as no response to prior Bz-containing regimen or disease progression within 60 days of a Bz-containing regimen. Patients were also relapsed, refractory, intolerant, and/or ineligible, to treatment with an IMiD (thalidomide or lenalidomide). The date patients satisfied the above entry criteria was defined as time zero (T0). Clinical and laboratory data from diagnosis and individual relapses were collected along with details of all MM drug therapies before and after T0. Responses were assessed by IMWG or EBMT criteria. The goal of the study was to compare the characteristics of patients who satisfy the above inclusion criteria, the therapies employed prior to and after T0 and clinical outcome among these patients from different parts of the world. Results: The mean (median, range) time to reaching T0 from diagnosis was 4.5 (4.0, 12.8), 4.2 (3.2, 18.6), and 3.2 (2.8, 9.6) years from diagnosis for patients from US, Europe and Korea, respectively, P=0.021. The mean (median, range) number of therapies for the three groups were 8 (8, 13), 4 (4, 10), 5 (4, 7), respectively; P<0.001. The response rates (>=PR) to the initial therapy at diagnosis were 56%, 77% and 49% respectively for the US, European and Korean cohorts. Overall 220 patients had at least one therapy after T0, and 114 (52%) had a novel agent (Bz, len or thal) containing regimen as their first treatment after T0. Patients in US were more likely to receive additional therapies after the first post-T0 therapy; 62%, 32%, and 12% of patients from US, Europe and Korea, respectively, began a second post-T0 regimen within 2 years following time zero. The median number of therapies post T0 was 2, 1, and 1 for patients in US, Europe and Korea respectively. The response rates to the first regimen after T0 were 15%, 33% and 19% for the US, European and Korean cohorts, and were similar between those receiving a regimen with one of the novel drugs compared to rest. Patients younger than 60 years and those with prior transplants were more likely to respond to post T0 regimens. The median time to progression or death from T0was similar for the three patient cohorts, 5 months (Figure 1A). The median overall survival (95% CI) from T0 was 13 months (10, 16), 7 (5,9) and 8 (4,9) respectively for the US, European and Korean cohorts (Figure 1B). Conventional prognostic factors, especially the ISS stage was predictive of OS post T0. Additionally, presence of extramedullary disease was associated with a shorter overall survival. Conclusion: The results of the current study demonstrate significant differences between different parts of the world in terms of the treatment patterns both in the setting of initial therapy as well as treatment of relapsed disease. Patients in the US were more likely to receive multiple regimens both before and after T0. This is likely a reflection of increasing numbers of new drugs that have gone into clinical trials and thus enhancing options. The study further highlights the poor outcome of patients who have relapsed after the new drugs, irrespective of the geographical location. Disclosures: Kumar: Merck: Consultancy, Honoraria; Genzyme: Consultancy; Celgene: Consultancy. Richardson:Millennium: ; Celgene: ; Johnson & Johnson: ; Novartis: ; Bristol Myers Squibb:. Moreau:Millennium Pharmaceuticals, Inc.: Advisory board, Honoraria; Janssen: Advisory board, Honoraria. Sonneveld:Millennium Pharmaceuticals, Inc.: 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; Onyx: Membership on an entity's Board of Directors or advisory committees, Research Funding. Siegel:Merck: Honoraria; Millenium: Honoraria, Research Funding, Speakers Bureau. San Miguel:Janssen-Cilag: Honoraria; Celgene: Honoraria. Palumbo:celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees. Durie:Celgene: Membership on an entity's Board of Directors or advisory committees.

Abstract Background: Lenalidomide with dexamethasone (Rd) is a standard of care for patients with previously untreated multiple myeloma. SWOG S0777, a randomized phase III trial, has compared Rd with bortezomib, lenalidomide and dexamethasone (VRd). The primary end point is progression-free survival (PFS) using a pre-specified one-sided stratified log rank test at a significance level of 0.02. The stratification factors are International Staging System (ISS) stage (I, II or III) and intent to transplant (yes or no), a total of 6 strata. Overall response rate (ORR), overall survival (OS) and safety are secondary end points. Methods: This analysis includes 474 patients evaluable for survival endpoints: 232 patients were randomized to Rd and 242 patients to VRd. Rd patients received lenalidomide 25 mg/day on days 1-21 and dexamethasone 40 mg/day on days 1, 8, 15 and 22 of a 28-day cycle. VRd patients received lenalidomide 25 mg/day on days 1-14 and dexamethasone 20/mg/day on days 1, 2, 4, 5, 8, 9, 11 and 12 plus bortezomib 1.3 mg/m2 IV push on days 1, 4, 8 and 11 of a 21-day cycle. All patients received aspirin 325 mg/day and VRd patients received HSV prophylaxis per institutional standard. Induction was six 28-day cycles of Rd and eight 21-day cycles of VRd followed by Rd maintenance for all patients until progression, unacceptable toxicity or withdrawal of consent. Initial analyses utilized the pre-specified one-sided stratified log rank test. Results: Data are presented for VRd followed by Rd throughout. Between 2008 and 2012, 525 patients from 48 institutions were randomized. Fifty-one patients, 29 randomized to Rd and 22 randomized to RVd, were ineligible for the following reasons: missing, insufficient or early or late baseline labs (40); not meeting requirements of measurable disease (6); inadequate marrow function (1); inadequate creatinine clearance (1); prior malignancy (1); prior therapy (1); and more than 2 weeks of prior steroid therapy (1). The pre-specified significance level of 0.02 was reached in the log rank testing. The stratified hazard ratio (HR) was 0.742 (96% Wald confidence interval: 0.579, 0.951), and the one-sided stratified log rank p-value for PFS (VRd vs. Rd) was 0.0066. The OS was improved for VRd vs. Rd with HR = 0.666; two-sided log-rank p-value = 0.0114. The PFS and OS survival charts are displayed below. Median PFS was 43 months (VRd) versus 31 months (Rd). Median OS was not reached (VRd) versus 63 months (Rd). Patient characteristics were well-matched between VRd and Rd with the exception of fewer women (37% vs. 47%: P = 0.033) and fewer older patients (≥ 65 years 38% vs. 48%: P = 0.042) receiving VRd. With univariate Cox regression analysis correlates of better PFS/OS were: use of VRd (HR 0.72/0.65; P = 0.006); hemogoblin ≥10 g/dl (HR 1.17/1.43; P = 0.2/0.026) and lower ISS disease stage (HR 1.35/1.98; P = 0.014/< 0.001). The ORR for VRd was 71.07% versus 63.79% for Rd. The adverse events by CTC category and toxicity category were fairly well balanced. The most common hematologic adverse events (≥ Grade 3 and at least possibly attributable to therapy) were low hemoglobin (RVd=13%; Rd=16%), leukopenia (RVd=14%; Rd=16%), lymphopenia (RVd=23%; Rd=18%), neutropenia (RVd=19%; Rd=21%), and thrombocytopenia (RVd=18%; Rd=14%). The most common non-hematologic adverse events (≥ Grade 3 and at least possibly attributable to therapy) were: fatigue (RVd=16%; Rd=14%), sensory neuropathy (RVd=23%; Rd=3%), hyperglycemia (RVd=7%; Rd=11%), thrombosis/embolism (RVd=8%; Rd=9%), hypokalemia (RVd=9%; Rd=6%), muscle weakness (RVd=7%; Rd=4%), diarrhea (RVd=8%; Rd=2%), and dehydration (RVd=8%; Rd=2%). As expected ≥ Grade 3 neuropathy was more frequent with VRd (24% vs. 5%: P < 0.0001). Sixteen patients experienced a second primary malignancy, 7 (3%) on VRd and 9 (4%) on Rd. Conclusion: The addition of bortezomib to lenalidomide dexamethasone for induction therapy in previously untreated myeloma results in a statistically significant and clinically meaningful improvement in PFS as well as better OS. VRd had an acceptable safety and tolerability profile despite increased neurotoxicity and represents a potential new standard of care. Support: NIH/NCI/NCTN grants CA180888, CA180819, CA180821, CA180820; and in part by Millennium Pharmaceuticals, Inc., The Takeda Oncology Company, for provision of study drug. Figure 1. Figure 1. Figure 2. Figure 2. Disclosures Durie: Johnson & Johnson: Consultancy; Takeda: Consultancy; Onyx: Consultancy; Celgene: Consultancy. Abidi:Millennium: Research Funding. Epstein:University of Arkansas for Medical Sciences: Employment. Reu:Takeda/Millennium: Research Funding; Novartis: Research Funding; Celgene: Research Funding. Orlowski:BioTheryX, Inc.: Membership on an entity's Board of Directors or advisory committees; Janssen Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Research Funding; Spectrum Pharmaceuticals: Research Funding; Onyx Pharmaceuticals: Consultancy, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Millennium Pharmaceuticals: Consultancy, Research Funding; Acetylon: Membership on an entity's Board of Directors or advisory committees; Genentech: Consultancy; Forma Therapeutics: Consultancy; Array BioPharma: Consultancy, Research Funding. Barlogie:Dana Farber Cancer Institute: Other: Travel Stipend; International Workshop on Waldenström's Macroglobulinemia: Other: Travel Stipend; ComtecMed- World Congress on Controversies in Hematology: Other: Travel Stipend; European School of Haematology- International Conference on Multiple Myeloma: Other: Travel Stipend; Celgene: Consultancy, Research Funding; Millennium: Consultancy, Research Funding; Myeloma Health, LLC: Patents & Royalties: Co-inventor of patents and patent applications related to use of GEP in cancer medicine licensed to Myeloma Health, LLC; Multiple Myeloma Research Foundation: Other: Travel Stipend.

Abstract Abstract 3031 Background: Treatment-induced peripheral neuropathy (TIPN) can be a debilitating side-effect as well as a therapy-limiting complication in multiple myeloma (MM). Thalidomide (THAL) and bortezomib (BTZ) are two therapies frequently associated with TIPN in MM. Carfilzomib (CFZ) is a novel and highly selective epoxyketone proteasome inhibitor that differs from BTZ both structurally and mechanistically. CFZ overcomes BTZ-resistance in vitro, lacks the off-target activities of BTZ in preclinical studies, and does not cause neurotoxicity in long-term (6–9 month) chronic animal toxicology studies (Kirk et al. Blood, 2008). Single-agent CFZ produces durable responses in relapsed or refractory (R/R) MM without dose-limiting PN. Here we report on the clinical experience with single-agent CFZ in the Ph 2b PX-171-003-A1 trial in patients (pts) with R/R MM and Grade (G) 1/2 PN at study entry. Methods: Pts received CFZ at 20 mg/m2 IV, on Days 1, 2, 8, 9, 15, and 16 in a 28-day cycle (C) for the first C followed by 27 mg/m2 thereafter for up to 12 C. Pts completing 12 C were eligible to enter an extension study. Responses and progression were determined according to the International Myeloma Working Group (IMWG) criteria and were assessed by an Independent Review Committee (IRC). PN data were collected for all pts on study and included neuropathy history, neurological physical exam and PN-related quality of life data (FACT-GOG/NTx v 4.0 scores) collected at screening. Prospective neurological exams and subjective reporting of PN occurred every 2 cycles until study discontinuation to proactively assess for PN. Adverse event (AE) data were also collected, with AEs reported as ‘neuropathy peripheral', ‘neuropathic pain', ‘neuropathy', and ‘peripheral sensory neuropathy' included as PN. AE reports of ‘paraesthesias' and ‘dysesthesias' were counted separately. Results: Of the 266 pts with R/R MM in PX-171-003-A1, 237 (89%) had a history of PN which was attributable to prior anti-myeloma therapy, including THAL (108 pts/41%), BTZ (134 pts/50%), or both BTZ and THAL (17 pts/6.4%). 206 of the 266 (77%) had G1/2 PN at baseline and a median disease duration of 5.9 years. This subset with active PN at baseline had received a median of 5 prior lines of therapy (range 1–20), with a median 13 anti-myeloma agents, and a median of 2 prior BTZ- and 1 prior THAL- containing regimens. Prior therapies included 100% BTZ, and 100% either THAL (77%) or prior lenalidomide (95%). Responses in the subset of pts with baseline PN were nearly identical to those seen in the full study population with an overall response rate (ORR; ≥ partial response [PR]) of 24% and a clinical benefit response rate (CBR; ≥ minimal response [MR]) of 36%. The median duration of response (≥PR) was 7.4 mo (95% CI 5.6–not reached) and median duration of MR was 6.3 months in both the overall and PN-baseline cohorts. OS and TTP data will also be reported. The most common treatment-emergent ≥G3 adverse events regardless of relationship to study drug were primarily hematologic and were as follows: thrombocytopenia (24%), anemia (21%), lymphopenia (11%), pneumonia (9%), neutropenia (9%), fatigue (7%), hypercalcemia (7%), and hyponatremia (6%). Although 77% of pts had G1/2 PN at baseline, new onset PN was infrequent with PN AEs of any grade reported in 31 (15%) pts and G3 PN reported in only 1 (0.4%) pt. New onset or worsening of paraesthesias (6.8%) and dysesthesias (0%) was also infrequent. Conclusions: Analysis of the subset of pts (77%) with active PN (G1/2) in this single-agent Ph 2 trial of CFZ in pts with R/R MM demonstrated that PN has no impact on depth or durability of responses, or on the tolerability of CFZ, in heavily pretreated pts with multiply relapsed and refractory MM. Reports of new or worsening PN were very uncommon, and paraesthesias and dysesthesia were generally infrequent and mild. CFZ can be given to pts with baseline PN with little risk of exacerbation; prolonged therapy is possible in this population. Disclosures: Martin: Celgene: Honoraria; Onyx: Consultancy. Singhal:Celgene: Speakers Bureau; Takeda/Millenium: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Onyx: Research Funding. Vij:Onyx: Honoraria. Wang:Celgene: Research Funding; Onyx: Research Funding; Millenium: Research Funding; Novartis: Research Funding. Stewart:Millennium: Consultancy; Celgene: Honoraria. 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. Lonial:Millennium: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; BMS: Consultancy, Research Funding; Onyx: Consultancy, Research Funding. Jakubowiak:Millennium Pharmaceuticals, Inc.: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Honoraria; 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. Kukreti:Celgene: Honoraria; Roche: Honoraria; Ortho Biotech: Honoraria. Alsina:Millenium: Consultancy, Research Funding; Celgene: Research Funding; Novartis: Consultancy. Zonder:Millenium: Consultancy, Honoraria, Research Funding; Cephalon: Research Funding; Celgene: Honoraria. Wong:Onyx Pharmaceuticals: Employment. Vallone:Onyx Pharmaceuticals: Employment. Chang:Onyx Pharmaceuticals: Employment. Kauffman:Onyx Pharmaceuticals: Employment. Siegel:Millenium: Consultancy, Honoraria; Celgene: Consultancy, Honoraria.

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 Abstract 1942 Background: The impact of cytogenetic abnormalities on the response to therapies and survival in patients (pts) with multiple myeloma (MM) has been well established in the literature. Bortezomib (BTZ), either alone or in combination with other agents, has been shown to overcome the adverse impact of several common unfavorable cytogenetic features. In addition, responses with lenalidomide (LEN)/dexamethasone and pomalidomide have also been reported in patients with unfavorable cytogenetic profiles. Carfilzomib (CFZ) is a novel and highly selective epoxyketone proteasome inhibitor which produces durable single-agent activity in pts with R/R MM. The objective of this analysis was to evaluate the influence of cytogenetics in a large Ph 2b study (PX-171-003-A1), with single-agent CFZ in pts with R/R MM. Methods: Of the 266 pts enrolled in the 003-A1 study, 229 pts (86%) were response evaluable and had available metaphase cytogenetics and/or fluorescence in situ hybridization (FISH) analyses for hypodiploidy, chromosome 13 deletions, del 17p13, t(4:14), and t(14;16) chromosomal abnormalities. Metaphase cytogenetic analyses were available for 200 pts (75%) and FISH results were available for 205 pts (77%). All pts received CFZ at 20 mg/m2 IV on days 1, 2, 8, 9, 15, and 16 in a 28-day cycle (C) in C1 followed by 27 mg/m2 in each C thereafter for up to 12 C. Pts who completed 12 C of therapy were eligible to continue CFZ on an extension study. For the analysis, overall response rate was defined as ≥PR by International Myeloma Working Group (IMWG) criteria. Clinical benefit response (CBR; ORR + MR as defined by EBMT criteria) was also assessed. All responses were assessed and confirmed by an Independent Response Review Committee (IRC). Results: The median age in this subpopulation was 64 yrs. Pts must have had disease that was relapsed after ≥2 regimens including BTZ and either thalidomide (THAL) or LEN, and must have been refractory to their most recent regimen. In this heavily pre-treated pt population, pts had received median of 13 prior anti-myeloma drugs and a median of 5 prior regimens. 99.6% of pts had previously received treatment with BTZ, 74% received prior thalidomide, 94% prior lenalidomide, and 74% prior stem cell transplantation. The ORR (≥PR) for the pts with available metaphase cytogenetics and/or FISH analyses was 25% and the CBR (≥MR) was 38%. 71 of 229 pts (31%) had at least one cytogenetic abnormality. Of these, 27/71 (38%) pts had abnormalities detected via metaphase cytogenetics, 24 (34%) pts were detected by FISH and 20 (28%) pts had abnormalities by both methods. The presence of deletion 13 or hypodiploidy by cytogenetics or del17p13, t(4;14), or t(14;16) by FISH did not significantly impact the ORR. Specifically, 30% of pts with ≥1 abnormality responded compared to 23% with none. The CBR was also unaffected at 34% vs. 39% for pts with ≥1 and no abnormalities, respectively. For all pts in this analysis, the median duration of response (DOR) was 8 months (95% CI 6–10). For pts with ≥1 abnormality, the DOR was 7 months (95% CI 4–10) and did not differ significantly from the DOR of 8 months (95% CI 6–not reached) in pts with no abnormalities. A complete breakdown of response categories and time-to-progression (TTP) will also be presented. Conclusions: CFZ demonstrated durable and comparable activity in pts with R/R MM in both the absence or presence of one or more cytogenetic abnormalities including hypodiploidy, chromosome 13 deletions, del 17p13, t(4:14), or t(14;16). Notably, these results are consistent with data obtained in another Ph2 study with CFZ in pts with relapsed MM following 1–3 prior therapies and who had abnormal cytogenetics (PX-171-004). The results of the present study suggest that durable responses to CFZ can be achieved in heavily pretreated patients and responses are not impacted by poor prognostic cytogenetic features. Disclosures: Jakubowiak: Millennium Pharmaceuticals, Inc.: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Honoraria; 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. Martin:Celgene: Honoraria; Onyx: Consultancy. Singhal:Celgene: Speakers Bureau; Takeda/Millenium: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Onyx : Research Funding. Wang:Celgene: Research Funding; Onyx: Research Funding; Millenium: Research Funding; Novartis: Research Funding. Vij:Onyx: Honoraria. 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. Lonial:Millennium: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; BMS: Consultancy, Research Funding; Onyx: Consultancy, Research Funding. Kukreti:Celgene: Honoraria; Roche: Honoraria; Ortho Biotech: Honoraria. Bray:Onyx Pharmaceuticals: Employment. Vallone:Onyx Pharmaceuticals: Employment. Kauffman:Onyx Pharmaceuticals: Employment. Siegel:Millenium: Consultancy, Honoraria; Celgene: Consultancy, Honoraria.

Abstract Abstract 1954 Background: Carfilzomib (CFZ) is a novel, highly selective epoxyketone proteasome inhibitor that produces potent and sustained proteasome inhibition both in vitro and in vivo. CFZ appears to lack many of the off-target activities frequently associated with bortezomib (BTZ). This lack of off-target activity may account for observed differences in tolerability seen with CFZ including lack of significant neuropathy and minimal neutropenia and diarrhea. To date, single agent CFZ has been evaluated in Ph 1 and 2 studies in >600 patients, and the vast majority of patients treated had relapsed and/or refractory (R/R) MM. In these settings, CFZ has demonstrated durable single-agent activity and was well-tolerated in patients with advanced stage disease with co-morbidities including baseline neuropathy or renal insufficiency. Here we present the results of parallel safety analyses of patients from four Ph 1 and 2 studies with CFZ. Materials and Methods: The present safety analyses were based on data accumulated from patients enrolled in the following trials: PX-171-003 A0 (R/R MM), PX-171-003 A1 (R/R MM), PX-171-004 (relapsed MM), and PX-171-005 (R/R MM with varying degrees of renal function). In all studies, the treatment schedule was based on a 28-day cycle, dosing CFZ QDx2 each week for 3 weeks (Days 1, 2, 8, 9, 15, 16) with 12 days of rest. Doses of CFZ ranged from 15–20 mg/m2 in cycle 1 (005 [15 mg/m2], 003 A0 and A1, 004 [20 mg/m2]). In three studies CFZ was escalated to 27 mg/m2 after the first cycle, as tolerated (003- A1, 004-BTZ naïve subset and 005). In PX-171-005, low-dose dexamethasone was added in the majority of patients. Results: CFZ was well-tolerated by patients across the 4 studies analyzed. The most common treatment-emergent adverse events (AEs) included fatigue, anemia, nausea, dyspnea, and thrombocytopenia. Detailed descriptions of the incidence of treatment-related AEs (all Grades (G) in ≥25% of pts; ≥G3 in ≥5% of pts) across studies are presented in the table. Peripheral neuropathy (PN) occurred infrequently across all 4 studies (N= 517), with only 20 patients (3.9%) experiencing PN of any G and only 2 patients (0.4%) with G3 PN. Febrile neutropenia was likewise uncommon, occurring in only 3 patients (0.6%). Serious treatment emergent AEs (SAEs) occurring in ≥1% of patients and considered possibly/probably related to study drug across all 4 studies included: pneumonia (3.5%), congestive cardiac failure (2.5%), acute renal failure (1.7%), pyrexia (1.2%), and dyspnea (1%). Conclusions: Despite a substantial disease burden present in the patient populations described here, CFZ was well-tolerated by patients with MM across all studies examined. The excellent safety/tolerability profile of CFZ has permitted prolonged administration (in some cases over 24 mos of continuous therapy including extension study) with minimal dose modifications or discontinuations due to toxicity. The low levels of neuropathy seen with CFZ make this agent a potentially important treatment option for patients with pre-existing neuropathy from either underlying disease or prior neuropathic anti-myeloma therapy. Disclosures: Singhal: Celgene: Speakers Bureau; Takeda/Millenium: Membership on an entity’s Board of Directors or advisory committees, Speakers Bureau; Onyx: Research Funding. Siegel:Millenium: Consultancy, Honoraria; Celgene: Consultancy, Honoraria. Martin:Celgene: Honoraria; Onyx: Consultancy. Vij:Onyx: Honoraria. Wang:Celgene: Research Funding; Onyx: Research Funding; Millenium: Research Funding; Novartis: 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. Lonial:Millennium: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; BMS: Consultancy, Research Funding; Onyx: Consultancy, Research Funding. Kukreti:Celgene: Honoraria; Roche: Honoraria; Ortho Biotech: Honoraria. Zonder:Millenium: Consultancy, Honoraria, Research Funding; Cephalon: Research Funding; Celgene: Honoraria. Wong:Onyx Pharmaceuticals: Employment. McCulloch:Onyx Pharmaceuticals: Employment. Kauffman:Onyx Pharmaceuticals: Employment. Niesvizky:Celgene: Consultancy, Membership on an entity’s Board of Directors or advisory committees, Research Funding, Speakers Bureau; Millenium: Consultancy, Membership on an entity’s Board of Directors or advisory committees, Research Funding, Speakers Bureau; Onyx: Consultancy, Research Funding. Stewart:Millennium: Consultancy; Celgene: Honoraria. 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.

Abstract Abstract 303 Background: Carfilzomib (CFZ) is a novel proteasome inhibitor that binds its target selectively and irreversibly, resulting in greater and more sustained proteasomal inhibition compared to BTZ (Demo et al, Cancer Res 2007). CFZ overcomes BTZ-resistance in vitro (Kuhn et al, Blood 2007) and in a previous Phase 2 study (PX-171-003), single-agent CFZ achieved durable responses and maintained disease control [e.g. ≥ Stable Disease (SD)] in patients with progressive multiple myeloma (MM) despite treatment with essentially all available agents. PX-171-004 is an ongoing Phase 2 study of CFZ monotherapy in MM patients with relapsed or refractory disease following 1–3 prior therapies. Here we report updated data for the BTZ-treated cohort. Methods: Patients with relapsed or refractory (defined as < 25% response or disease progression during therapy) MM were enrolled and stratified based on prior BTZ exposure (e.g. BTZ-naïve and BTZ-treated). For the BTZ-treated cohort, tolerability and response to prior BTZ [≥ Minor Response (MR)] was not required. CFZ 20 mg/m2 IV was administered on Days 1, 2, 8, 9, 15 and 16 every 28 days, for up to 12 cycles. The primary endpoint was Overall Response Rate (ORR) [≥ Partial Response (PR)] by IMWG criteria. Secondary endpoints included Clinical Benefit Response (CBR = ORR + MR) and safety. Results: Thirty-five BTZ-treated patients were enrolled. Six (17%) patients had previously received BTZ exclusively as a single agent, 15 (43%) received BTZ as part of a chemotherapy combination and 10 (29%) received BTZ as part of a stem cell transplant (SCT) regimen. An additional 4 (11%) received BTZ in a chemotherapy combination as well as part of a separate transplant regimen. Other prior therapies included alkylators (89%), SCT (81%), thalidomide (69%), lenalidomide (37%), and anthracyclines (31%). Six (17%) patients had disease refractory to BTZ and 9 (26%) additional patients had discontinued BTZ due to toxicities. At baseline, 19 (54 %) patients had an ECOG score ≥ 1, 17 (49%) patients had neuropathy of Grade ≥ 1, 9 (26%) patients had impaired renal function (CrCl <60 mL/min) and 9 (26%) had diabetes. The median time since diagnosis was 3.6 years (range 1.2–13.2). To date, the mean number of CFZ doses administered was 29.3 (∼5 four-week cycles; range 4–72 doses, 0.7–12 cycles). Thirty-three patients who initiated therapy were evaluable for response per protocol. The ORR was 18% (6/33), including 1 CR and 5 PRs. An additional 4 (12%) patients had MR (CBR= 30%) and 13 (39%) had SD for ≥ 6 weeks. For evaluable patients who were either refractory or intolerant to their prior BTZ therapy, responses to CFZ included 1 PR and 1 MR and 8 SDs. The most common adverse events (AEs) (≥ 30% patients) were primarily Grades 1/2 and included fatigue (57%), nausea (54%), vomiting (37%), dyspnea (34%), diarrhea (34%), anemia (31%), increased creatinine (31%) and upper respiratory tract infection (31%). Grade 3/4 AEs occurring in ≥ 10% of patients were anemia (14.3%) and neutropenia (11.4%). There were no reports of febrile neutropenia. Dose modifications were rarely required. Peripheral neuropathy (PN) was uncommon (4 patients, 11%); only 1 patient had a Grade 3 event that lasted < 36 hours and did not result in missed doses or dose modification. None of the 9 patients with baseline renal impairment were discontinued for renal AEs. To date, 6 (17%) patients have completed the full 12-cycle protocol at the initial dose and schedule, 6 (17%) remain on study and 1 patient has received > 19 cycles on a recently initiated extended treatment protocol. Conclusions: In a BTZ-exposed population that includes BTZ treatment failures and significant comorbidities (e.g. diabetes, renal insufficiency, etc), the 18% ORR (CBR 30%) is notable for this steroid- and anthracycline-sparing regimen. Single-agent CFZ is well tolerated, even in patients with renal insufficiency, and both myelosuppression and PN are uncommon. These data support the continuing evaluation of CFZ as a safe and effective treatment option in MM. Disclosures: 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. Wang:Proteolix, Inc.: Research Funding. Stewart:Genzyme, Celgene, Millenium, Proteolix: Honoraria; Takeda, Millenium: Research Funding; Takeda-Millenium, Celgene, Novartis, Amgen: Consultancy. Kukreti:Celgene: Honoraria. Jakubowiak:Millennium Pharmaceuticals, Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Centocor Ortho Biotech: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Exelixis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Bristol-Myers-Squibb: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. 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. Belch:Ortho Biotech: Honoraria, Research Funding. Bahlis:Celgene: Honoraria, Speakers Bureau; Ortho Biotech: Honoraria, Speakers Bureau. Le:Proteolix, Inc.: Employment. Kunkel:Proteolix: Consultancy, Employment. Bennett:Proteolix: Employment. Kauffman:Proteolix, Inc.: Employment. Vij:Proteolix, Inc.: Consultancy, Research Funding.