Orlowski, Robert Z.

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

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

Abstract Background: SWOG S0777, a randomized phase III trial, compared bortezomib, lenalidomide and dexamethasone (VRd) with lenalidomide and dexamethasone (Rd). The primary end point was progression-free survival (PFS) using a pre-specified one-sided stratified log rank test at a significance level of 0.02. The stratification factors were International Staging System (ISS) stage (I, II or III) and intent to transplant (yes or no), among a total of 6 strata. Overall response rate (ORR), overall survival (OS) and safety were secondary end points. Results of the primary analysis of this trial were published in Lancet (2016, Volume 389, Issue 10068, 519 - 527). Methods: This updated analysis includes 460 patients evaluable for survival endpoints: 225 eligible and analyzable patients were randomized to Rd and 235 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 VZV prophylaxis per institutional standard. The 6-month 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. Results: Between 2008 and 2012, 525 patients from 48 institutions were randomized. Patient data have been rigorously updated for this analysis based upon a May 15, 2018 datalock. The median follow up is now 84 months (7 years). The median PFS is 41 months for VRd and 29 months for Rd: stratified hazard ratio (96% Wald Confidence Interval) was 0.742 (0.594, 0.928) and one-sided stratified log-rank P-value 0.003 (see Figure 1). The median OS for VRd is still not reached with median OS for Rd being 69 months: stratified hazard ratio (96% Wald Confidence Interval) was 0.709 (0.543, 0.926) and stratified two-sided P-value was 0.0114 (see Figure 2). The impact of age was assessed in several ways including using 3 cutoffs (<65 years; 65-75 years; >75 years) and multivariate cox proportional hazards regression analyses adjusted for age. As in prior analyses, both PFS and OS were improved with VRd versus Rd adjusting for age (P-values: 0.013 [PFS]; 0.033 [OS])). Depth of response was assessed incorporating new serial data and additional bone marrow results. The CR plus VGPR was 74.9% for VRd versus CR plus VGPR of 53.7% for Rd (P-value 0.006 for response differences using a stratified Cochran-Mantel- Haenszel analysis). The median duration of lenalidomide plus dexamethasone maintenance was 17.4 months. The number of second cancers was 19/235 (8%) with VRd and 16/225 (7%) with 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 with follow up of 7 years. VRd had an acceptable safety and tolerability profile and continues to represent an appropriate standard of care irrespective of age. Disclosures Durie: Takeda: Consultancy; Amgen: Consultancy; Celgene: Consultancy; Johnson & Johnson: Consultancy. Abidi:Millenium Takeda: Research Funding. Epstein:University of Arkansas for Medical Sciences: Employment. Dispenzieri:Celgene, Takeda, Prothena, Jannsen, Pfizer, Alnylam, GSK: Research Funding. Reu:Bristol Myers Squibb: Employment; Millenium Takeda: Consultancy; Novartis: Consultancy, Research Funding; Celgene: Research Funding. Orlowski:Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Millenium Pharmaceuticals: Consultancy, Research Funding; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; BioTheryX, Inc: Consultancy, Membership on an entity's Board of Directors or advisory committees; Genentech: Consultancy; Janssen Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees; Poseida: Research Funding; Bristol Myers Squibb: Consultancy. Barlogie:Dana Farber Cancer Institute: Other: travel stipend; Celgene: Consultancy, Research Funding; International Workshop on Waldenström's Macroglobulinemia: Other: travel stipend; Multiple Myeloma Research Foundation: Other: travel stipend; European School of Haematology- International Conference on Multiple Myeloma: Other: travel stipend; 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; ComtecMed- World Congress on Controversies in Hematology: Other: travel stipend; Millenium: Consultancy, Research Funding.

Abstract Abstract 3165 Background: Accrual to large oncology group studies in the United States is often slower than planned, especially in less common malignancies such as Multiple Myeloma (MM). To improve the treatment of patients with MM, it is essential that we address the barriers to accrual (BtA) to national clinical trials. The NCI Myeloma Steering Committee (MYSC) formed the Accrual Working Group (AWG), charged to analyze this problem. Methods: The members of the MYSC have developed a list of 10 potential BtA to NCI MM-CT under the leadership of the AWG at meetings conducted in person and by monthly telephone conference. This list was distributed via Survey Monkey among investigators and research staff of the SWOG, ECOG/ACRIN and Alliance research bases for the purpose of ranking the perceived importance of the 10 selected BtA. Responses based on a 0–5 Likert Scale were analyzed as continuous and categorical. For the latter, responses were grouped: Impedes Accrual – No (0,1), Yes (2–5); Significantly Impedes Accrual – No (0–3), Yes (4,5). Results: 246 survey responses were received. 50 participants who indicated that they had never attempted to or actually never enrolled a patient into a MM-CT were excluded. Of 196 responders, 61% had enrolled at least 5 patients, 43% practiced in academic centers (A) and 57% in community centers (C). 26% identified themselves as research staff, 74% as primarily physician investigators including Principal Investigators (12%). 78% have current access to NCI MM-CT. 46% identified their research base affiliation with SWOG, 20% with ECOG/ACRIN, 17% with Alliance, 17% as CTSU, NRG and other. The majority of survey responders confirmed agreement in the perception that all 10 identified BtA impede accrual, ranging from 60–84% depending on the specific barrier identified, while significant impediment to accrual ascribed to these BtA ranged from 22–47%. The perceived barriers most often cited as impeding accrual were (1) spectrum of available treatment options, (2) level of reimbursement for clinical trial related expenses and (3) patient‘s need for prompt treatment intervention (84%, 80%, 76% respectively). The first two barriers along with the requirement that patients receive their treatment exclusively at the NCI designated treatment site were rated most often as significantly impeding accrual (37%, 47%, 34% respectively). The first two were also identified most often as perceived BtA independent of practice setting (A, C), type of research engagement (physician investigator, research staff) and level of experience with MM-CT. Interestingly, the perception that patients must receive their treatment at the NCI designated treatment site and competing industry sponsored clinical trials were substantially more often cited as impeding accrual in academic centers compared to community centers and by physician investigators compared to research staff. The complexity of required diagnostic work up and the complexity of the treatment protocol and follow up testing were substantially more often cited as BtA in the community setting and by research staff compared to their peers in the academic setting and by physician investigators. The NCI MYSC AWG has proposed specific solutions to potentially lower perceived BtA. These include guidelines to allow protocol specific administration of commercially available agents by the patient‘s local oncologist, a simplified diagnostic work up and treatment plan and eligibility inclusion of patients who have received up to one cycle of specified urgent therapy prior to enrollment in MM-CT. Conclusions: We have queried experienced clinical investigators and research staff on 10 potential MM-CT specific BtA and found substantial consensus among responding participants in this survey. There are apparent differences in perceived BtA between the respondents from academic and community centers as well as between research staff and physician investigators. These data suggest that a structured approach to identification of BtA to clinical trials is feasible and creates opportunities to overcome them. This may have application to clinical trials across other diseases and may also lead to improvements in accrual. Disclosures: Barlogie: Celgene, IMF, MMRF, Millennium, Genzyme: Consultancy; Celgene, IMF, Millennium: Honoraria; Celgene, Novartis, NCI, Millennium, Onyx, Icon: Research Funding; GEP: Patents & Royalties.

Abstract Introduction: Carfilzomib (CFZ) is a structurally- and mechanistically-novel proteasome inhibitor (PI) of the peptide epoxyketone class that exhibits a high level of selectivity for the unique N-terminal threonine active sites within the proteasome. CFZ is similar to bortezomib (BTZ; VELCADE®), in that it is a potent inhibitor of the chymotrypsin-like activity, but unlike BTZ, CFZ has shown minimal cross-reactivity with the other catalytic sites within the proteasome or across other protease classes. Preclinical human tumor xenograft models indicate that consecutive day (D1, D2) dosing resulting in 48 hours of proteasome suppression was superior to split dosing (D1, D4). Methods: This phase 1 sequential dose escalation trial tested an intensive proteasome inhibition schedule with CFZ administered as an intravenous push (IVP) daily (QD) for 5 consecutive days on a 14 day cycle. The doses administered ranged from 1.2 mg/m2 to 20 mg/m2. Multiple myeloma (MM), non-Hodgkin’s lymphoma (NHL) that included mantle cell lymphoma (MCL), Hodgkin’s disease (HD), or Waldenström’s macroglobulinemia (WM) were eligible if they had relapsed after 2 or more prior therapies. Results: A total of 29 subjects have been treated. The minimal effective dose (MED) was 11 mg/m2. A maximum of 80% proteasome inhibition was achieved in peripheral blood and mononuclear cells at ≥15 mg/m2. Five responses have occurred in 14 patients (6 MM, 3 MCL, 1 WM, 4 NHL) enrolled at ≥ the MED: 1 MM partial response (PR), 2 MM minimal responses (MR), 1 WM MR and one macroscopic CR in a patient with gastrointestinal MCL. Responses occurred in patients whose disease had failed therapy with BTZ, immunomodulatory agents, and stem cell transplant. Four NHL patients have had stable disease and remained on treatment for up to 7 months. Dose limiting toxicity reported at 20 mg/m2 included febrile neutropenia (reversible) and grade 4 thrombocytopenia. Grade 3 (25%) or grade 4 events (8%) were primarily hematologic events. Most withdrawals occurred due to the inconvenience of frequent visits, or progressive disease. Conclusions: This study demonstrates that intensive CFZ dosing leading to sustained proteasome inhibition is well tolerated. The selectivity of the epoxyketone class of PI may promote a favorable safety profile. Furthermore, antitumor responses in heavily pretreated patients suggest non-cross resistant activity. Phase 2 trials in MM and solid tumors are proceeding with an alternate IV schedule. An oral agent suitable for frequent dosing schedules is under development.

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

Abstract Abstract 127 The precise molecular mechanism of action and targets through which thalidomide and related immunomodulatory drugs (IMiDs) exert their anti-tumor effects remains unclear. A landmark paper has recently identified cereblon (CRBN) as a primary target of thalidomide teratogenicity. We hypothesized that this protein would also be required for myeloma (MM) cytotoxicity. To examine this issue we first tested 12 MM cell lines: 4 of which (OCIMY5, OPM1, SKMM2 and KMS12 PE) were very resistant to treatment with both lenalidomide and pomalidomide. Of these, OCIMY5 and OPM1 showed CRBN gene expression levels at the bottom 10% across the human MM cell lines. We next used CRBN shRNA lentiviral expression constructs to knock down CRBN in 5 human-derived myeloma cell lines (HMCLs) (KMS18, MM1.S, H929, OPM2 and JJN3). HMCLs infected with CRBN shRNAs have a significant reduction of CRBN expression and subsequent diminished cell viability (reduced 65–78%). Surviving MM cells with CRBN knock down demonstrate an acquired (essentially complete) resistance to lenalidomide when compared with controls but retained sensitivity to melphalan, dexamethasone and bortezomib. Gene expression changes induced by lenalidomide were dramatically suppressed in those CRBN depleted cells, e.g., OPM2 cells only showed 30 down regulated (3% of control) and 150 up-regulated genes (24% of control) after lenalidomide treatment, further emphasizing that CRBN is required for lenalidomide activity. We next compared by array comparative genomic hybridization the differences between MM1.S (lenalidomide sensitive) and its isogenic lenalidomide resistant line (MM1.S res), generated by culturing MM1.S in gradually increasing concentrations of lenalidomide. Only three structural abnormalities were noted differentiating the two lines one of which was deletion of CRBN. In fact the baseline MM1.S cell line has a minor population of 9% of cells with CRBN depletion which becomes dominant after lenalidomide treatment. However, further scrutiny of CRBN status in additional HMCLs and MM patients (irrespective of therapy and stage) suggested that copy-number abnormalities affecting this gene are uncommon events in MM, with 12% of HMCLs (7 out of 60) and only 1.2% of MM patients (3 out of 238) showing CRBN monoallelic deletion. Next, we examined by quantitative polymerase chain reaction (Q-PCR) ten MM patients who had become resistant to lenalidomide therapy. CRBN expression level by Q-PCR in 8 of 10 patient samples had a significant reduction (20% to 90% reduction compared to baseline) at time of drug resistance, suggesting CRBN expression as a potential biomarker to predict IMiD response. Notably however some clearly resistant patients have normal CRBN, demonstrating that while CRBN is absolutely required for response, multiple resistance mechanisms are likely present. By gene and protein expression downstream targets of CRBN were examined and included interferon regulatory factor 4 (IRF4) previously reported to also be a target of lenalidomide. In summary, we demonstrate here that CRBN is essential for IMiD activity and preliminary data support that low levels of CRBN predict for poor drug response. In addition, our data suggest that CRBN is a critical molecule but not the unique source of IMiD resistance. We suggest that the “IMiDs” be renamed Cereblon binding small molecules to more accurately reflect their mechanism of action. Disclosures: Orlowski: Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding.

Abstract Background: (CFZ) is a novel proteasome inhibitor of the epoxyketone class that exhibits a high level of selectivity for the proteasome and has been shown in a phase 1 study to result in greater than 80% proteasome inhibition on a QDx2 consecutive day schedule. We piloted this agent in MM patients with relapsed disease after one to three prior therapies. Methods: PX-171-004 is an open-label, multicenter study. Pts are stratified into bortezomib (BTZ) naïve, BTZ responsive (> 6 month response) or BTZ non-responsive(< 6 months response) cohorts. Pts received CFZ 20 mg/m2 IV Days 1, 2, 8, 9, 15 and 16 every 28 days, for up to 12 cycles. Dexamethasone 4 mg po was administered prior to each dose in cycle 1. Responses were evaluated by the International Uniform Response Criteria for Multiple Myeloma. Results: 31 patients were enrolled, including 45% BTZ naïve, 45% BTZ responsive, and 10% BTZ non-responsive. 29 pts initiated therapy, completed at least one cycle of CFZ, had measurable M-protein and were evaluable for response. The mean number of prior therapies (excluding transplant) was 2.4;65% received prior thalidomide(THAL), 36% prior lenalidomide (LEN) and 87% prior stem cell transplant (SCT).To date, pts received a median of 4 cycles (range 1–8) of CFZ. 19 pts started at least 4 cycles, and 17 remain on therapy. In the evaluable BTZ naïve population (n=13), the overall response rate (ORR) was 54%, including 1 complete response (CR), 2 very good partial responses (VGPR), and 4 partial responses (PR). There were 4 additional pts with stable disease (SD). In 1 pt with insufficient data to evaluate response, due to tumor lysis syndrome (TLS) onset after 2 CFZ doses, an M-protein drop was noted that suggested a PR. Time to response was rapid, frequently occurring in the 1st cycle. There have been no progressions in this subset. With a median follow-up of 109 days, the time-to-progression(TTP) has not yet been reached, and all responders remain in remission. In 16 evaluable BTZ prior treated pts, 3 pts (19%) achieved PR, 1 (6%) pt achieved a minimal response (MR, as defined by EBMT criteria), and 9 pts had SD. The median TTP is 169 days for this subset. CFZ was generally well tolerated. The most common non-hematologic adverse events (AEs) were fatigue (61%), nausea (58%), vomiting (36%), and insomnia (32%). Worsening of hematologic parameters: neutropenia (32%), anemia (29%), and thrombocytopenia (23%) were primarily Grade 1/2; Grade 3/4 occurred in 10% or less of pts. Reports of peripheral neuropathy (PN) were uncommon. Increased creatinine, both drug and non-drug related, was seen in 5 pts (16%), but treatment was discontinued in only 1 pt due to a renal adverse event. Possible tumor lysis was reported in 2 BTZ naïve patients and resulted in early drug discontinuation in 1 pt, as described above; the 2nd event was fatal. Conclusions: The preliminary results of this trial indicate that CFZ has substantial activity as a single agent in relapsed MM patients, with an ORR of >50% in BTZ naïve patients, indicating better activity in this pt population. CFZ was generally well tolerated, and toxicities were manageable. TLS, which was observed in 2 pts, may be a reflection of the robust drug activity of CFZ. As observed in prior studies with CFZ, reports of PN were uncommon. These observations support further evaluation of CFZ as a promising new agent in MM. Enrollment in this study is ongoing, and additional studies of CFZ in combination with other chemotherapy agents in MM pts are underway.

Abstract Abstract 430 Background: Peripheral neuropathy (PN) is a feature of multiple myeloma (MM) itself as well as a debilitating side effect and major dose-limiting toxicity of thalidomide (THAL) and bortezomib (BTZ) (Chaudry et al, J Peripher Nerv Syst. 2008). Although the mechanism of BTZ-induced PN (BIPN) is unknown, PN may not be a proteasome inhibitor class effect. Carfilzomib (CFZ) is a highly selective proteasome inhibitor with activity in relapsed or refractory MM. CFZ overcomes BTZ-resistance in vitro (Kuhn et al, Blood 2007), lacks the off-target activities of BTZ (Kapur et al, Blood 2008), and does not cause neurotoxicity in long-term chronic (e.g. up to 9 months) animal toxicology studies (Kirk et al, Blood 2008). In Phase I and 1b/2 trials (total n=138), CFZ was not associated with dose-limiting PN. Here we report on the experience of CFZ treatment from two ongoing Phase 2 trials in relapsed or refractory MM. Methods: Patients with relapsed or refractory MM received CFZ, 20 mg/m2 IV, Days 1, 2, 8, 9, 15, and 16 in a 28-day cycle for up to 12 cycles on studies PX-171-003 and PX-171-004. Neuropathy history, neurological physical exam and PN-related quality of life data (FACT-GOG/NTx v 4.0 scores) were collected at screening. Prospective neurological exams and subjective reporting of PN using the FACT-GOG/Ntx subscale v.4 questionnaire occurred every 2 cycles until study discontinuation to proactively assess for PN. Adverse Event (AE) data were also collected. AEs reported as ‘neuropathy peripheral', ‘neuropathic pain', ‘neuropathy', and ‘peripheral sensory neuropathy' were included as PN. AE reports of ‘paraesthesias' and ‘dysesthesias' were counted separately. Results: To date, baseline data are availabel for 136 patients. At screening, 73 (54%) patients had active PN, including 64 (47%) with Grade (G) 1 and 9 (7%) with G2. 111 (82%) patients had a history of PN which was attributed to prior chemotherapy, 86 cases of which were attributed to either THAL or BTZ. THAL was implicated in 57 cases, BTZ in 45 cases, and both THAL and BTZ in 17 cases. For 27 of these patients, PN was the primary reason for THAL or BTZ discontinuation. The mean number of CFZ doses was 27 (4.5 four-week cycles) and 27 (20%) patients completed at least 8 cycles. Peripheral neuropathy AEs (all grades) were reported in 21 (15%) patients; 12 (9%) cases were considered possibly related to CFZ. Grade ≥ 3 PN was reported in only 3 (2%) patients. In one patient, the Grade 3 neuropathy lasted from treatment days 2 to 3 (i.e., < 36 hours) and resolved; the patient continued on CFZ at full dose for 30 days before discontinuing study due to progressive MM. In a second patient, Grade 3 neuropathy occurred on study day 91. The dose was reduced from 20 mg/m2 to 15 mg/m2, at the same twice-weekly frequency; the PN resolved to G1 and the patient continued on therapy until day 133. The third patient had G3 PN that occurred from days 260-281 and resolved to G1 while still on full dose CFZ. This patient completed the full 12-cycle protocol (∼1 year CFZ treatment). Paraesthesias and dysesthesia were reported in 10 (7%) patients; all were G1 or 2. There were no missed doses or CFZ treatment discontinuations due to PN, paraesthesias or dysesthesias. Comparative FACT-GOG/Ntx subscale scores were availabel for 95 patients. There was no statistically significant change in FACT-GOG/NTx scores from baseline to the end of the study. Neurological exams did not identify any additional peripheral neuropathy beyond those reported as AEs. Conclusions: In MM patients receiving CFZ therapy, reports of PN, paraesthesias and dysesthesia are generally mild and do not result in missed doses or CFZ discontinuation, allowing long-term treatment and prolonged disease control. These data, along with the experience from other clinical trials, indicate that PN is not a class effect of proteasome inhibitors. Disclosures: Vij: Proteolix: Consultancy, Research Funding. Wang:Proteolix, Inc.: Research Funding. Stewart:Genzyme, Celgene, Millenium, Proteolix: Honoraria; Takeda, Millenium: Research Funding; Takeda-Millenium, Celgene, Novartis, Amgen: Consultancy. Lonial:Celgene: Consultancy; Millennium: Consultancy, Research Funding; BMS: Consultancy; Novartis: Consultancy; Gloucester: Research Funding. Trudel:Celgene: Honoraria, Speakers Bureau; Ortho Biotech: 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. Belch:Ortho Biotech: Honoraria, Research Funding. Bahlis:Celgene: Honoraria, Speakers Bureau; Ortho Biotech: Honoraria, Speakers Bureau. Le:Proteolix, Inc.: Employment. Cruickshank:Proteolix, Inc.: Employment. Bennett:Proteolix: Employment. Molineaux:Proteolix, Inc.: Employment, Equity Ownership. 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.

Abstract Background: Patients (Pts) with multiple myeloma (MM) who relapse within 12 months of autologous stem cell transplantation (SCT) have a poor prognosis. As reported by Mahmood et al. (ASCO 2007), of 432 pts who received SCT at the Mayo Clinic between 1994–2005, those with early relapse within 12 months (94/432– 22%) showed poorer median overall survival. Kaplan-Meier estimates of 12-month survival from the date of first relapse were 37% for pts relapsing within 12 months after SCT as compared to 85% for those relapsing after 12 months. In that study, pts had received regimens other than B. In a recent report of a large, phase III study (DOXIL-MMY3001), the combination of PLD+B improved time to progression (TTP) as compared to B alone (Orlowski et al. JCO 2007). The present analysis examined the 12-month post-randomization survival of patients who had early (<12 months) vs. late (≥12 months) relapse following SCT, as well as the effect of PLD+B vs. B alone in pts who had relapsed early. Methods: This was a retrospective analysis of 646 pts who received intravenous B, 1.3 mg/m2 on days 1,4,8 and 11 of every 21-day cycle ± PLD, 30 mg/m2 on day 4. Results: 359 pts had previously received transplant, 114 (32%) of whom relapsed within 12 months from SCT. The median age, gender distribution, time from diagnosis trial enrollment, measures of disease burden (M-Protein levels and B2M) and renal function were comparable between the early and late relapse groups. There was no difference in overall response rates [complete + partial response (CR+PR)] or very good PR (VGPR) rates between the two groups, or between treatment arms within each group. There was no significant difference in TTP between early vs. late relapse groups (HR=0.94). 12-month survival from randomization was significantly lower in the early relapse group as compared to late relapse (83% vs. 92% respectively, p=0.009). However, within the early relapse group 12-months post-randomization survival rate was significantly superior following treatment with PLD+B as compared to B alone [52/56 patients (93%) vs. 43/58 patients (74%) respectively, p=0.01]. Correspondingly, TTP was better in this group with PLD+B vs. B alone (276 days vs. 205 days respectively, p=0.13). Overall, the toxicity profiles of the combination and B alone were comparable regardless of early or late relapse following SCT. Conclusions: The present analysis of the MMY3001 study corroborates the prior Mayo observation of lower survival in MM pts relapsing within 12 months of SCT. Importantly, it demonstrates that PLD+B may provide a therapeutic advantage for high-risk MM pts with early relapse following SCT.