Munshi, Nikhil C.

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 The 2-3 fold excess risk of multiple myeloma (MM) among family members of cases suggests a heritable contribution to risk. Recently, a genome-wide association study (GWAS) identified two genome-wide significant and one promising novel loci associated with multiple myeloma risk. To confirm these associations and identify additional novel risk loci, we performed a four-center, genome-wide association meta-analysis. Methods A fixed effects model was used for the meta-analysis which included a total of 1248 cases and 1485 controls, all of European descent, genotyped and analyzed at four separate centers with samples contributed by 10 studies. After quality control and imputation using the 1000 Genomes Project, the analysis included ∼9.5 million variants (λ=1.024). Associations between (single nucleotide polymorphisms) SNP genotypes and MM risk were evaluated under a log-additive model of inheritance, with each study adjusting for age, sex, and up to 10 principal components to control for population stratification. Promising results were replicated in an independent set of 1587 cases and 1770 controls using TaqMan, for a total of 2835 and 3255 cases and controls, respectively, in a combined meta-analysis. Results The discovery meta-analysis did not reveal any genome-wide significant associations (defined as p<5 x 10-8). We used a novel pruning algorithm to identify the top 35 most promising single nucleotide polymorphisms (SNPs) to advance to replication. We successfully genotyped 22 SNPs in the replication set. In the combined discovery and replication meta-analysis, rs1345359 at 12q23.1 was the most strongly associated SNP (P=9 x 10-8, Table 1). The variant allele C was associated with reduced risk (odds ratio discovery set [OR]= 0.69, OR replication set = 0.78, OR combined = 0.74). A second locus at 20q13.2 (rs150220835), was associated with a two-fold increased risk (P=1.22 x 10-6), a borderline increased risk (P=0.0900) and 45% increased risk (P=2.44 X 10-5) in the discovery, replication, and combined analysis sets respectively (Table 1). We also confirmed the association between MM risk and two previously published SNPs (rs4487645, p=0.0007and rs105251, p=0.0044) (Broderick et al., Nat. Genet., 2011). The third previously suggested SNP (rs6746082) was of nominal significance (p=0.0517) in the meta-analysis. Discussion We confirmed the association between MM risk and two previously published SNPs and identified a possible association with a novel SNP in chromosome 12q23.1 (rs1345359). This SNP is not located in a gene nor associated with biofeatures in ENCODE, thus further examination of correlated SNPs is necessary to identify a functional SNP linked to this locus. We also found suggestive evidence for a second locus at 20q13.2 requiring additional replication. Larger studies would improve risk variant discovery for this rare hematologic malignancy. Disclosures: Wolf: Celgene: Honoraria, Research Funding; Millenium: Honoraria; Onyx: Honoraria. Anderson:Celgene, Millennium, BMS, Onyx: Membership on an entity’s Board of Directors or advisory committees; Acetylon, Oncopep: Scientific Founder , Scientific Founder Other.

Abstract NF-κB is a transcriptional factor promoting tumor cell growth and inhibition of apoptosis via regulating expression of proteins modulating cell cycle and anti-apoptosis. NF-κB is constitutively associated with an inhibitor (IκB), which is phosphorylated by IκB kinase (IKK) upon cell stimulation (ie, TNFα) and subsequently degraded by ubiquitin-proteasome pathway, thereby allowing NF-κB to translocate to nucleus. We have previously shown that an IKK inhibitor PS-1145 partially (20–50%) inhibits MM cell proliferation; however, it inhibits both IL-6 secretion from BMSCs triggered by MM cell adhesion and proliferation of MM cells adherent to BMSCs. Targeting IKKβ is therefore a possible therapeutic option for inhibition of MM cell growth in the bone marrow microenvironment by downregulating NF-κB activity. In this study, we further delineated the biologic significance of IKK inhibition in MM cells using IKKβ specific inhibitor MLN120B (Millennium Pharmaceuticals, Cambridge, MA). MLN120B induced 60–90% growth inhibition in cells from the MM cell lines RPMI8226, RPMI/Dox40, RPMI/LR5, U266, and INA-6; on the other hand, it induced only 25–30% inhibition in MM.1S and MM.1R cells, assessed by 72 h tritiated-thymidine uptake. Importantly, neither IL-6 nor IGF-1 overcomes the growth inhibitory effect of MLN120B in both MM.1S and U266 cells. Interestingly, MLN120B significantly augmented TNFα-induced cytotoxicity in MM.1S cells. We next examined whether MLN120B could enhance the cytotoxicity of other agents. MLN120B augmented growth inhibition triggered by doxorubicin and melphalan in RPMI8226 and IL-6 dependent INA-6 cell line. We therefore studied growth inhibitory effect of MLN120B in the presence of bone marrow stromal cells (BMSCs). MLN120B inhibited 70–80% of constitutive IL-6 secretion from BMSCs, without toxicity. Importantly, MLN120B almost completely blocked stimulation of MM.1S, U266 and INA-4 cell growth and IL-6 secretion from BMSCs induced by binding of tumor cells to BMSCs. Finally, MLN120B overcame the protective effect of BMSCs, cell adhesion mediated drug resistance, against dexamethasone in MM.1S cells. Taken together, our data demonstrate that an IKKβ inhibitor induces cytotoxicity in MM cells in the BM milieu, providing the framework for clinical trials of these novel agents to improve patient outcome in MM.

Abstract Angiogenesis or formation of new blood vessels from existing blood vessels, in contrast to vasculogenesis or de novo formation of new vessels, plays an important role in the progression and spread of most cancers. Multiple myeloma (MM) is characterized by increased microvessel density (MVD), a quantitative estimate of angiogenesis, which correlates with stage of disease. MVD increases with progression from MGUS to smoldering MM to newly diagnosed MM and relapsed MM. It is a powerful prognostic factor, predicting for overall survival. To further elucidate the biological basis for the prognostic value of increased angiogenesis in MM, we studied the interactions of MM cells with endothelial cells using HUVECS as a model system. Co-culture of MM cells (MM1.S, OPM2, U266) with HUVECS induced tumor cell proliferation. Enhanced tumor cell proliferation correlated with the number of HUVECs and was greater than that triggered by co-culture with patient bone marrow stromal cells. When HUVECs were fixed prior to co-culture there was a significant decrease in the tumor cell proliferation. Addition of HUVEC conditioned media to the MM cell lines also induced proliferation. Importantly, HUVECS protected against anti-MM agents including conventional agents (Dexamethasone, Doxorubicin, Melphalan) and novel drugs (Revlimid™). The protective effect afforded by co-culture was lost on HUVEC fixation. Intracellular signaling events following MM cell-endothelial cell contact were studied to understand the mechanisms of the proliferative and protective effects. Western blotting demonstrated activation of the JAK/STAT, PI3K/Akt and the MAPK pathways, mediating proliferation and survival. Ongoing studies focused on understanding cytokine as well as adhesion-mediated interactions between the endothelial cells and the MM cells will identify targets for new therapeutic approaches in MM.

Abstract The pursuit of rationale, targeted therapies relies on a detailed understanding of the mechanisms that subvert normal growth control and lead to development of Multiple Myeloma (MM). To further define the mechanistic steps that contribute to MM pathogenesis, we examined mRNA expression profiles of CD138+ plasma cells obtained from normal, Monoclonal Gammopathy of Unknown Significance (MGUS), and MM patient samples. Using genomic results in combination with molecular and cellular-based assays, we demonstrate a critical role for UBC9 and the sumoylation pathway in myeloma cell growth and survival. Notably, Reverse Transcriptase Polymerase Chain Reaction (RT-PCR) demonstrated a ten-fold induction in UBC9; a gene that encodes the sole Sumo-conjugating enzyme in human cells. We demonstrated an elevation of UBC9 in both MM primary patient cells and in a number of patient-derived MM cell lines. In addition, a number of other sumoylation pathway components were induced in primary MM cells at the gene and protein level relative to normal plasma cells. We believe that induction of UBC9 is an early genetic event in the pathogenesis of MM since the induction was observed at the gene and protein level in plasma cells from patients with MGUS. Importantly, UBC9 induction was functionally significant since a different pattern of sumoylation was observed in total cell lysate from MM patient plasma cells relative to that of normal plasma cells. Furthermore, overexpresion of a mutant form of UBC9 deficient in Sumo-conjugating activity increased the sensitivity of plasma cells to apoptosis by chemotherapeutic agents and these cells were impaired in other essential functions that included cellular proliferation, DNA synthesis, resistance to apoptosis and adhesion to bone marrow stroma. Immunoblotting of MM patient cell lysates also demonstrated a similar induction of the UBC9 gene product (Ubc9) as well as induction of the Sumo ligases Nse2 and PIAS1. These studies identify UBC9 as a target upregulated early in the pathogenesis of MM and indicate a critical role for sumoylation in disrupting the controls that govern normal plasma cell growth. To further develop prognostically relevant molecular signatures and classifications of MM subtypes, we analyzed the survival outcome of patients that expressed induced levels of UBC9, as well as other sumoylation components, and demonstrate significantly reduced survival of such patients following current treatment modalities. The results provide evidence for critical role of UBC9 and sumoylation in MM pathogenesis. Furthermore, sumoylation pattern may serve as a therapeutic target in MM, help stratify clinical management and provide a framework for the identification of sumoylation pathway targets that govern MM cell growth and progression.

Abstract Background BT062 (Biotest AG Dreieich, Germany) is an antibody-drug conjugate, comprising the anti-CD138 chimerized MAb (nBT062) and the maytansinoid DM4 as cytotoxic agent. Once bound to CD138 on a target cell, the conjugate is internalized and releases DM4, leading to target cell death. CD138 (Syndecan-1) is highly overexpressed on various solid tumors and in hematological malignancies, and represents one of the most specific target antigens for identification of multiple myeloma (MM) cells. Data from two studies investigating BT062 as single agent demonstrated an acceptable tolerability profile and evidence of clinical activity in patients with heavily pretreated relapsed and/or refractory MM (1, 2). Preclinical studies showed enhanced anti-MM activity when BT062 was combined with lenalidomide and dexamethasone (Len/Dex). Based on these data, a Phase I/IIa study in MM was initiated to evaluate the safety and efficacy of BT062 in combination with Len/Dex. Objectives To determine the dose-limiting toxicities (DLTs), the maximum tolerated dose (MTD), the recommended phase II dose (RPTD), pharmacokinetics (PK), and anti-MM activity of increasing doses of BT062 (days 1, 8, and 15, every 4 weeks) in combination with Len (25 mg, daily on days 1-21) and low dose Dex (40 mg on days 1, 8, 15, and 22) in patients with relapsed and/or refractory MM. Methods This is a prospective, open label, dose-escalation, multicenter Phase I/IIa study. The Phase I part includes dose escalation, and the Phase IIa the expansion of the MTD or RPTD cohort. Patients aged ≥18 years with relapsed and/or refractory MM who have failed at least one prior therapy were eligible to participate. Prior treatment with Len and/or Dex was allowed. Patients with clinical response (or no evidence of progressive disease) and without unacceptable toxicities were eligible for additional treatment cycles. Patients were enrolled in cohorts of at least 3 at each dose level; DLT in the first cycle triggered cohort expansion. Toxicities were assessed by CTCAE v4 and clinical response was assessed according to International Myeloma Working Group criteria. Results As of July 2013, a total of 15 patients have received BT062 at dose levels of 80 mg/m2 (N=3), 100 mg/m2 (N=6) or 120 mg/m2 (N=6). Two patients at the highest dose level discontinued study due to toxicity (DLT), another patient withdrew consent. The other 12 patients remain on treatment; median duration 144 days (range 8–385). The median number of prior therapies was 4 (range 1–11), 87% of patients had prior Len exposure, and 50% were Len/Dex refractory. The maximum administered dose (MAD) has been reached at 120 mg/m2, with mucosal inflammation (CTC grade 3) as DLT in one, and anemia (CTC grade 3) in a second of the 6 patients treated at this dose level. About 85% of reported Adverse Events (AE) were of CTC grade 1 or 2. The most common reported AEs were fatigue, hypokalemia, and diarrhea. Amongst the 9 patients currently evaluable for efficacy, responses were observed across all dose levels with a overall response rate (ORR) of 78%; including 1 patient with complete response (120 mg/m2), 1 patient with very good partial response (80 mg/m2), and 5 patients with partial response (80 and 100 mg/m2). Two other patients achieved disease stabilization, resulting in a clinical benefit in 100% of the evaluated patients. Interestingly, partial response was observed in 3 patients refractory to prior treatment with Len/Dex. The MTD has been defined as 100 mg/m2 and is currently expanded to further evaluate the safety and efficacy of BT062 at the RPTD. Conclusion Preliminary data from this ongoing study indicate that BT062 is well tolerated in combination with Len/Dex at dose levels that induce responses in patients with relapsed and/or refractory multiple myeloma, including Len/Dex-refractory patients. Updated results on safety and efficacy will be presented. References 1. Jagannath et al, BT062, an Antibody-Drug Conjugate Directed Against CD138, Shows Clinical Activity in Patients with Relapsed or Relapsed/Refractory Multiple Myeloma. Blood. 2011; 118: Abstract 305. 2. Heffner et al, BT062, an Antibody-Drug Conjugate Directed Against CD138, Given Weekly for 3 Weeks in Each 4 Week Cycle: Safety and Further Evidence of Clinical Activity. Blood. 2012; 120: Abstract 4042. Disclosures: Somlo: Celgene: Research Funding, Speakers Bureau; NIH: Research Funding; Millennium: Speakers Bureau. Heffner:Genentech: Honoraria, Research Funding; Celgene: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding; Biotest: Honoraria, Research Funding; Onyx: Honoraria, Research Funding; Amgen: Honoraria, Research Funding; Pharmacyclics: Honoraria, Research Funding. Siegel:Millennium: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Speakers Bureau; Onyx: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Speakers Bureau; Celgene: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Speakers Bureau. Zimmerman:Celgene: Honoraria; Millennium: Honoraria; Onyx: Honoraria. Jagannath:Millennium: Honoraria; Celgene: Honoraria. Munshi:Celgene: Consultancy; Novartis: Consultancy; Millennium: Consultancy. Lonial:Millennium: Consultancy; Celgene: Consultancy; Novartis: Consultancy; BMS: Consultancy; Sanofi: Consultancy; Onyx: Consultancy. Ruehle:Biotest AG: Employment. Chavan:Biotest Pharmaceuticals: Employment. Patel:Biotest Pharmaceuticals: Employment. Rothenburger:Biotest AG: Employment. Wartenberg-Demand:Biotest AG: Employment. Haeder:Biotest AG: Employment. Anderson:Gilead: Consultancy; Sanofi Aventis: Consultancy; Onyx: Consultancy; Celgene: Consultancy; Acetylon: Equity Ownership; Oncopep: Equity Ownership.

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

Abstract Background Ixazomib, the first oral proteasome inhibitor, is approved by the US FDA, in combination with Rd, for the treatment of MM patients (pts) who have received at least 1 prior therapy. Approval was based on the double-blind, placebo-controlled phase 3 TOURMALINE-MM1 study (NCT01564537) in 722 pts with RRMM (Moreau et al, N Engl J Med 2016), in which IRd showed superior PFS versus placebo-Rd (HR 0.74) at the final prespecified analysis, with limited additional toxicity. Prespecified subgroup analyses showed a consistent PFS benefit with IRd, but with a differential treatment effect according to prior therapy exposure. An exploratory study objective was to evaluate potential relationships between treatment outcomes and tumor gene expression patterns. c-MYC is a proto-oncogene that encodes a transcription factor regulating cell proliferation, growth, protein translation, metabolism, and apoptosis, and increased c-MYC expression is involved in MM pathogenesis/progression. We analyzed the impact of c-MYC expression on PFS in RRMM pts treated with IRd or placebo-Rd. Methods Pts with RRMM after 1-3 prior lines of therapy were randomized 1:1 to receive oral ixazomib or placebo, plus lenalidomide and dexamethasone, until disease progression or unacceptable toxicity. Randomization was stratified by number of prior therapies (1 vs 2-3), proteasome inhibitor exposure, and ISS disease stage. The primary endpoint was PFS by independent review committee assessment. Data reported here are from the final prespecified statistical analysis of PFS (median follow-up ~15 months). Bone marrow aspirate samples were collected at screening for tumor gene expression analysis. Whole transcriptome sequencing (RNAseq) of bone marrow-sorted CD138+ cells was performed using the Illumina Truseq protocol on the Illumina HiSeq platform; this generated a median of 50 million paired-end reads (100 bp length) per sample. c-MYC expression was evaluated by treatment arm and according to number of prior therapies (1 vs 2-3). PFS was analyzed in subgroups dichotomized according to median c-MYC expression (c-MYC-high/c-MYC-low). Results RNAseq data were available for 59% (427/722) of enrolled pts; 213 (50%) had high and 219 (50%) had low c-MYC expression (dichotomized according to the median). Impact of c-MYC expression (high vs low) on PFS, irrespective of treatment arm, was not significant (p=0.98). However, a significant treatment effect of IRd vs placebo-Rd was only seen in pts with high c-MYC expression (interaction p=0.024); in these pts (IRd: n=109; placebo-Rd: n=104) a significant PFS benefit was seen with IRd (HR 0.41; 95% CI: 0.26-0.65, p=0.00011). Impact of c-MYC expression was then analyzed by number of prior therapies. In the overall TOURMALINE-MM1 population, per stratification, 212/213 pts in the IRd/placebo-Rd arms had 1 prior therapy, and 148/149 had 2-3 prior therapies. After median follow-up of ~15 months, median PFS in pts with 1 prior therapy was 20.6 vs 16.6 months with IRd vs placebo-Rd (HR 0.88; 95% CI: 0.65-1.20), and in pts with 2-3 prior therapies was not reached vs 12.9 months (HR 0.58; 95% CI: 0.40-0.84, p=0.0033). The level of c-MYC expression was shown to be significantly higher in pts with 2-3 prior therapies vs 1 prior therapy, with median expression of 6.94 (SD=1.71, n=177) vs 6.52 (SD=1.74, n=250) (log2 scale), t-test p-value 0.0153. In pts with 1 prior therapy, no differences in PFS were observed between pts with low c-MYC expression (HR 1; 95% CI: 0.59-1.8, p=0.934), while a prolonged PFS benefit was observed in pts with high c-MYC expression (HR 0.48; 95% CI: 0.26-0.88, p=0.0146) (Figure, A and B). In pts with 2-3 prior therapies, both the c-MYC-high and c-MYC-low pts showed improved PFS with IRd vs placebo-Rd; the difference in PFS was statistically significant only in c-MYC-high pts (HR 0.36; 95% CI: 0.18-0.72, p=0.00269) (Figure, C and D). Conclusions In TOURMALINE-MM1, c-MYC expression was higher in MM tumor samples from pts with 2-3 vs 1 prior therapies. The IRd regimen was active in c-MYC-high and c-MYC-low pts, but its impact on PFS vs placebo-Rd was greater in c-MYC-high pts, thus providing a potential explanation for the enhanced PFS benefit with IRd vs placebo-Rd in pts with 2-3 prior therapies. The PFS benefit with IRd in c-MYC-low pts with 2-3 prior lines suggests that, in advanced MM, further genomic alterations may also be contributing to ixazomib sensitivity. Disclosures Di Bacco: Millennium Pharmaceuticals Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment. Bahlis:BMS: Honoraria; Onyx: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Other: Travel Expenses, Research Funding, Speakers Bureau; Janssen: Consultancy, Honoraria, Other: Travel Expenses, Research Funding, Speakers Bureau. Avet-Loiseau:Takeda: Speakers Bureau; Janssen: Speakers Bureau; Celgene: Speakers Bureau; Sanofi: Speakers Bureau. Masszi:Janssen-Cilag: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees; BMS: Membership on an entity's Board of Directors or advisory committees. Ganly:Medipics: Equity Ownership; Novartis: Honoraria; Roche: Honoraria. Cavo:Bristol-Myers Squibb: Consultancy, Honoraria; Millennium: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; Janssen-Cilag: Consultancy, Honoraria; Celgene: Consultancy, Honoraria. Langer:Celgene: Consultancy; Takeda: Consultancy; Janssen: Consultancy; Amgen: Consultancy; Novartis: Consultancy. Kumar:Array BioPharma: Consultancy, Research Funding; Janssen: Consultancy, Research Funding; Sanofi: Consultancy, Research Funding; AbbVie: Research Funding; Onyx: Consultancy, Research Funding; Noxxon Pharma: Consultancy, Research Funding; Glycomimetics: Consultancy; Kesios: Consultancy; BMS: Consultancy; Millennium: Consultancy, Research Funding; Skyline: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Research Funding. Berg:Millennium Pharmaceuticals Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment. Lin:Millennium Pharmaceuticals Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment. Li:Millennium Pharmaceuticals Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment. Badola:Millennium Pharmaceuticals Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment. Shen:Millennium Pharmaceuticals Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment. Zhang:Millennium Pharmaceuticals Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment. Wang:Millennium Pharmaceuticals Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment. Esseltine:Takeda: Equity Ownership; Millennium Pharmaceuticals Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment; Johnson and Johnson: Equity Ownership. Luptakova:Takeda Oncology: Employment. van de Velde:Millennium Pharmaceuticals Inc., Cambridge, MA, USA, a wholly owned subsidiary of Takeda Pharmaceutical Company Limited: Employment. Richardson:Jazz Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees. Moreau:Bristol-Myers Squibb: Honoraria; Takeda: Honoraria; Celgene: Honoraria; Janssen: Honoraria, Speakers Bureau; Novartis: Honoraria; Amgen: Honoraria.

Abstract Interleukin-6 (IL-6) and insulin-like growth factor-1 (IGF-1) mediate growth of MM cells via activation of the mitogen-activated protein kinase (MAPK), JAK2/STAT3, and phosphatidylinositol 3′-kinase/Akt kinase (PI3-K/Akt) signaling cascades. We have previously demonstrated the in vitro and in vivo activity of Revlimid™ (CC-5013), an immunomodulatory analog (IMiD) of thalidomide, in MM. In the present study, we have examined the anti-MM activity of rapamycin, a specific mTOR inhibitor, combined with Revlimid™. This combination was highly synergistic at 0.1nmol/L of rapamycin with 0.1mmol/L of Revlimid™, and remained synergistic at higher concentrations. Based on the Chou-Talalay method, combination indices of < 1 were noted for all dose ranges of Revlimid™ and rapamycin, suggesting strong synergism. Importantly, this combination was able to overcome drug resistance when tested against MM cell lines resistant to conventional (doxorubicin, melphalan, dexamethasone) chemotherapy. Moreover, the combination, but not rapamycin alone, was able to overcome the growth advantage conferred on MM cells by IL-6, IGF-1, or adherence to bone marrow stromal cells (BMSCs). Cytotoxicity triggered by a combination of rapamycin with Revlimid™ resulted in apoptosis of MM cells. Furthermore, differential signaling cascades, including the MAPK and PI3-K/Akt pathways, were targeted by these drugs individually and in combination, suggesting the molecular mechanism by which they interfere with MM growth and survival. These studies therefore provide the framework for the clinical evaluation of targeted agents like mTOR inhibitors combined with immunomodulatory agents like Revlimid™ to improve patient outcome in MM.

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