Citations

Abstract Abstract 616 Background: We have shown the three drug combination of cyclophosphamide, bortezomib and dexamethasone (CyBorD) to be highly active therapy in newly diagnosed myeloma while allowing stem cell harvest and transplantation (Reeder et al. Leukemia 2009; 23:1337-1341). However, twice weekly bortezomib and high dose dexamethasone have been shown to cause significant toxicities. In a prospective Phase II we modified CyBorD by using bortezomib once weekly and reducing the dexamethasone to “low dose dex” after the first two cycles in an attempt to reduce toxicity (cohort 2). We report the efficacy and toxicity of this modified regimen and compare the results to standard CyBorD (cohort 1). Patients and methods: 63 untreated symptomatic patients were enrolled on this Phase II trial (33 on cohort 1 and 30 on cohort 2). All are evaluable for response and toxicity. Treatment on cohort 2 consisted of oral cyclophosphamide 300 mg/m2 and IV bortezomib 1.5 mg/m2 days 1, 8, 15 and 22 and dexamethasone 40 mg by mouth days 1-4, 9-12, 17-20 in cycles 1 and 2, then 40 mg po days 1, 8, 15, 22 in cycles 3 and beyond. Cohort 1 used standard dosing of bortezomib and high dose dexamethasone throughout. Each cycle was 28 days. Acyclovir and a quinolone antibiotic prophylaxis were routinely used. Patients were evaluated for response and toxicity every cycle and were offered stem cell harvest and transplant after the 4th cycle but could continue up to 12 cycles maximum. Results: The median age for all 63 patients was 61 (36-74) years and 48% were female. Durie-Salmon stages were 47% II and 50% III and ISS stages I 43%, II 36%, and III 21%. Twenty-four percent of patients were genetic high risk (t(4;14) or deletion 17). Cohorts I and II were matched for age, gender and ECOG PS. ISS stages were higher in cohort 1 than cohort 2 (II/III 67% vs. 44%). The intent to treat (ITT) ORR (≥PR) for all 63 patients (cohorts 1 and 2) is 90% with 60% ≥VGPR. For cohort 2 (modified CyBorD) the ITT overall response (≥PR) was 93% (CR: 5, nCR: 7, VGPR: 6, PR: 10) with 60% ≥VGPR and 40% ≥ nCR. Those completing all 4 cycles of therapy had 92% ORR (24/26) and 65% (17/26) ≥VGPR. A comparison of response rates in cohorts 1 and 2 is shown in table 1. These high and comparable response rates were associated with fewer grade 3+ adverse events (AE's) than in cohort 1 (37% vs. 48%) and no grade 3 peripheral neuropathy (PN). The median follow-up for all 63 patients is 12.4 (2.8-29.2) months and 95% of patients are alive with 87% free from progression. Conclusions: Modified CyBorD with weekly bortezomib and reduced dexamethasone retains the high activity seen in standard CyBorD, but is less toxic and more convenient. Interestingly, this modified regimen allowed higher overall doses of bortezomib (5.2 vs. 6.0 mg/m2 per cycle) yet overall neuropathy rates were similar. This combination of a weekly alkylating agent with bortezomib and dexamethasone is well tolerated and produces high response rates in newly diagnosed patients with multiple myeloma. Disclosures: Reeder: Millennium (MPI): Research Funding; Celgene: Research Funding. Reece:Ortho Biotech: Honoraria, Research Funding. Chen:Celgene: Honoraria, Research Funding; Ortho Biotech: Honoraria. Hentz:Millennium (MPI): Research Funding. Fonseca:Otsuka: Consultancy; BMS: Consultancy; Amgen: Consultancy; Medtronic: Consultancy; Genzyme: Consultancy. Bergsagel:Merck: Research Funding; Amgen: Consultancy; Genentech: Consultancy; Celgene: Consultancy. Stewart:Proteolix: Honoraria; Millennium (MPI): Research Funding.

Abstract Background: IMiDs are now recognized to promote the proteasomal degradation of IKZF1/3 and the transcriptional repression of MYC and IRF4. MYC locus rearrangement is a recurrent somatic event in MM and results in MYC repositioning near superenhancers (such as IGH@, IGL@ and others). The mechanisms of IMiDs-mediated downregulation of MYC in MM cells is not well understood, in particular it is unclear how IMiDs alter the activity of the super-enhancers driving MYC transcription. Methods and results: Transcriptome analysis (RNAseq) of MM cells (OPM2 and MM1S) treated with lenalidomide or upon the silencing of IKZF3 (lentiviral delivery of dox-inducible IKZF3 shRNA) confirmed the downregulation of MYC, IRF4 and among others the upregulation of other genes of interest such as CD38, DKK1, PDL1, FOXO3 and a host of genes involved in interferon response. Gene set enrichment analysis (GSEA) confirmed the enrichment of genes signatures associated with MYC as well as the interferon response. Notably, in t(4;14) MM cell lines we observed a significant downregulation of FGFR3 while the expression of WHSC1 was not affected. This finding was confirmed in a library of t(4;14) MM cell lines by qRT-PCR analysis. As FGFR3 is driven by the 3' IGH enhancer while WHSC1 is under the control of the intronic Em enhancer in t(4;14) MM cells, and in view of the known role of IKZF1/3 in class switch recombination, we postulated that IKZF1/3 regulate the 3' IGH enhancer activity and MYC expression in cells harbouring a MYC-IGH rearrangement. To validate this hypothesis we established the genome-wide distribution of IKZF1 in OPM2 and MM1S cells (both cell lines harbour an IGH-MYC rearrangement) by ChIP-Seq. Ikaros bound to 17660 loci of which 43% were associated with gene targets. Ikaros-binding motifs and other motifs such as STAT1, E2A, RUNX1 were also identified (MEME Tomtom and Jasper motif analysis) in the vicinity of Ikaros enrichment peaks. Importantly IKZF1 peaks also mapped to the IGH 3' enhancer loci and these results were confirmed by ChIP-PCR analysis. Of interest while no Ikaros peaks mapped to MYC (within 5 kb of TSS) by ChIP-seq, modest enrichment of Ikaros at MYC promoter was identified by ChIP-PCR in MM1S and KMS11 cells, and this enrichment was significantly attenuated by lenalidomide treatment. Since inhibition of MYC occurs as a consequence of depletion of the acetylated chromatin reader BRD4 at enhancers that drive MYC expression (Delmore et al., 2011), we examined the interaction between BRD4, IKZF1 and IMiDs treatment. Chip-Seq analysis revealed that BRD4 and IKZF1 are associated with most active enhancers and promoters in MM1S tumor cells. In particular, BRD4 and IKZF1 were enriched at the IGH 3'α2 enhancer locus. Importantly, treatment with lenalidomide (10μM, 4 hours), dramatically depleted IKZF1 and BRD4 enrichment at the 3' IGH enhancers (ChIP-PCR analysis). In contrast, treatment with the bromodomain inhibitor JQ1 depleted BRD4, but not IKZF1 from the IGH 3' enhancer locus. These findings suggest that IKZF1 regulates BRD4 binding to the 3' IGH enhancers and explain the selective effect of IMiDs on MYC transcription in transformed cells harboring a MYC rearrangement. In addition, these results suggest that IMiDs will affect MYC expression only in cells were MYC is driven by an IKZF1/IKZF3 responsive enhancer. Lastly we sought to explain how IKZF1 may regulate BRD4 enrichment at H3K27Ac marks in super-enhancer loci. Since Ikaros is a known integral component of the NuRD (nucleosome remodelling and histone deacetylase) complex, we examined whether lenalidomide treatment and the ensuing Ikaros depletion lead to local gain of NuRD at MYC TSS and depletion of H3K27 acetylation. CHD4 (helicase subunit of the NURD complex) and H3K27Ac ChIP-PCR analysis revealed significant accumulation of the NuRD complex at MYC TSS as well as reduced H3K27Ac at 3'IGH enhancers after IMiDs exposure in MM1S and OPM2 cells. Importantly, CHD4 silencing abrogated lenalidomide induced MYC transcriptional repression and cell death. Conclusion: In summary, our studies suggest that Ikaros drives MYC expression in MM cells harbouring an IGH-MYC rearrangement by regulating the accumulation of the acetylated chromatin reader BRD4 at the IGH 3' enhancer and preventing the NURD complex mediated depletion of H3K27Ac marks at these enhancers. Our findings also explain the IKZF1/3 dependent mechanism of IMiDs-mediated MYC transcriptional repression. Disclosures Neri: Celgene: Research Funding. Duggan:Jansen: Honoraria; Celgene: Honoraria. Keats:Translational Genomic Research Institute: Employment. Bahlis:Celgene: Consultancy, Honoraria, Research Funding, Speakers Bureau; Johnson & Johnson: Consultancy; Johnson & Johnson: Speakers Bureau; Johnson & Johnson: Research Funding; Amgen: Consultancy.

Abstract Abstract 3063 Background: The combination of Cyclophosphamide, Bortezomib, and Dexamethasone (CYBOR-D) is proven to be highly active and effective in multiple myeloma. (Reeder, Leukemia 2009) We aim to evaluate the safety and efficacy of this regimen in a separate plasma cell neoplasm, AL Amyloidosis. The primary endpoint of this study is hematologic response. Complete hematologic response is defined as normalization of the free light chain ratio with no evidence of a monoclonal protein by immunofixation. Partial hematologic response is defined as a 50% reduction in M-spike or absolute light chain level (Gertz Am J Heme 2006). Methods: We report a series of patients with symptomatic AL Amyloidosis who received treatment with a combination of Bortezomib (1.3mg/m2 on days 1, 4, 8, and 11 every 28 days or 1.5 mg/m2 weekly), Cyclophosphamide (300 mg/m2 orally weekly) and Dexamethasone (40 mg weekly). We include patients in this study regardless of autologous bone marrow transplant candidacy or previous treatment history. Results: Fifteen patients with AL amyloidosis received two to six cycles of CYBOR-D. The treatment history, bone marrow transplant candidacy prior to treatment, hematological response, and status of transplant after therapy are shown in table 1. Of note, 8 (53%) had symptomatic cardiac involvement all of whom had elevated levels of both cardiac biomarkers (Troponin T and B-natriuretic peptide). Complete hematological response occurred in 11 patients (73.3%) with partial hematological response in 3 patients (20.0%). One patient (6.6%) did not achieve a partial response but did receive autologous bone marrow transplant after treatment with CYBOR-D. Median time to response was 2 months. Six patients (40%) had objective evidence of kidney response to therapy with a greater than 50% decrease in proteinuria. Conclusions: CYBOR-D produces a rapid and complete hematological response in the majority of patients with AL amyloidosis regardless of previous treatment history or bone marrow transplant candidacy. Overall, it is well tolerated with few side effects that included peripheral neuropathy and infectious complications. Two patients originally determined to be not eligible for transplant improved sufficiently on CYBOR-D to become eligible and then went on to receive autologous bone marrow transplant. The retrospective nature and small sample size limit this study, and prospective, randomized studies are needed to further elucidate the role of this regimen in AL amyloidosis. Disclosures: Stewart: Millennium Pharmaceuticals, Inc.: Honoraria, Research Funding; Celgene: Honoraria. Fonseca:Amgen: Consultancy; Bristol-Myers Squibb: Consultancy; Celgene: Consultancy, Research Funding; Genzyme: Consultancy; Onyx: Research Funding; Otsuka: Consultancy; Medtronic: Consultancy.

Abstract Abstract 2834 Poster Board II-810 Background: Monoclonal gammopathy of undetermined significance (MGUS) results arises from a clonal proliferation of differentiated plasma cells and is a necessary precursor to development of multiple myeloma and some other B cell malignancies. Despite a high incidence in the general population (1-2% of adults in the 6th and 7th decades) and increased relative risk for later malignancy, there are few reports about the clinical course and prognosis of MGUS in long-term immunosuppressed patients. We aimed to evaluate the significance of MGUS in patients undergoing solid transplants in terms of clinical outcomes and rate of transformation to secondary B cell malignancy. Material and methods: We reviewed the medical records of 1493 patients on which kidney (living donor related, living donor-unrelated and deceased donor), liver and pancreatic transplants were performed at Mayo Clinic Arizona, between January 1, 1999 and July 31, 2009 to determine the incidence of MGUS and to further evaluate long-term follow up. At MCA patients are routinely screened using SPEP and for those where an M-spike is detected or suspected immunofixation is required for confirmation. MGUS was defined as previously reported. Patients who had anemia unrelated to their PCD were included. Statistical Methods: Patients were observed until death or, for those still alive, until July 2009. The major goal of the study was to assess the impact of MGUS on transplant outcomes and progression to active myeloma or related disorders. Patients who did not experience progression were censored at the time of last follow-up. Nominal variables were compared using Fisher's exact test. A two-tailed P value less than .05 was considered significant. Results In this series, SPEP was performed in 1199 out of 1593 cases (75%) before transplantation. The most common abnormalities detected by SPEP included a normal pattern (70%), polyclonal pattern (16.8%), hypoalbuminemia (8%), hypogammaglobulinemia (2.4%) and the presence of M spike (2.8%). Immunofixation revealed the presence of a monoclonal immunoglobulin in 34 patients: IgG 30 cases (88%), IgM in 2 (6%) and biclonal disease in 2 (6%). The median age at diagnosis of MGUS was 60 years (range, 46 to 84 years), and included 63.7% of males. Clinical characteristics of the MGUS cases are seen in Table 1. Two MGUS patients were diagnosed only after the transplant was performed (338 and 1082 days respectively). There was no association between post-transplant lymphoproliferative (PTLPD) and MGUS and even when some MGUS patients died (7/34, 20%) death was not associated with progression of the monoclonal clone or development of a PTLPD or other malignancy. MGUS does not impact transplant outcomes. PTLPD disorders developed in 6 cases and none was associated with a MGUS. After a median of 88 months no MGUS patient developed transformation to active myeloma or a related disorder. Overall survival after transplantation was not significantly different among MGUS and Non- MGUS cases (6.48 vs 8.36 years p>0.05). Discussion Despite the frequency of MGUS in the general population there are few studies which have assessed MGUS in solid organ transplant patients. An increased incidence of monoclonal gammopathy in patients with autoimmune disease and in older non-transplant populations suggests that impaired immunity might lead to development of MGUS and later monoclonal B-cell malignancies. Interestingly, we identified two cases where MGUS appeared after transplant. In this series, we report on the incidence and follow/up of MGUS in patients screened before transplantation. The primary outcome for transplant recipients is unaffected by the presence of MGUS and incidence is in accordance with the expected frequency (2.8%). Patients with MGUS do not appear to be at risk for progression due to chronic immunosuppression. Testing for MGUS before transplantation is not cost-efficient and therefore would not be recommended. To our knowledge this is the largest series of MGUS and transplant outcome yet reported. Disclosures: Stewart: Takeda-Millenium, Celgene, Novartis, Amgen: Consultancy; Takeda, Millenium: Research Funding; Genzyme, Celgene, Millenium, Proteolix: Honoraria.

Abstract Abstract 2403 Immunoglobulin light chain amyloidosis (AL) is a monoclonal plasma cell disorder characterized by the accumulation of monoclonal light chain fragments that have undergone a conformational transformation and deposit as amyloid fibrils in different tissues. High-dose melphalan (HDM) with autologous hematopoietic stem-cell transplant (ASCT) is increasingly used to treat patients (pts) with AL Amyloidosis. However, transplant-related mortality (TRM) is high, ranging between 13% to 43%. The survival benefit of HDM has been attributed to a patient-selection bias. Recently, a randomized clinical trial by Jaccard A et al, showed longer survival in the group assigned to receive melphalan plus dexamethasone (Mel/Dex) than in the group assigned to receive HDM. The present is a retrospective study aiming to define which pts with AL are most likely to benefit from HDM. Patients and Methods We retrospectively reviewed the medical records of all the pts included in the Princess Margaret Hospital Amyloidosis Database who underwent ASCT from January 2004 to March 2010 to determine: a) TRM, b) Hematological response (HR) and Organ response (OR) and c) Overall survival (OS). We included transplanted pts who had received no more than two previous courses of any chemotherapy regimen who did not have concurrent myeloma, and who had an Eastern Cooperative Oncology Group (ECOG) performance-status score of 2 or better. As part of the ASCT the stem cells were obtained from the peripheral blood with granulocyte colony-stimulating factor (G-CSF) alone (5 μ g/kg subcutaneously, twice daily). Pts then received HDM, 200 mg/m2 given intravenously on day 0, and stem cells were infused on day 1. The HDM was reduced to 140 mg/m2 for pts 65 years of age or older and for those with an important decrease of the ejection fraction, a calculated creatinine clearance of less than 30 ml per minute, or severe liver disease. HR and OR was assessed using 2004 Amyloidosis Consensus Response Criteria (Gertz, M et al, 2004). For statistical evaluation, HR was defined as observing complete or partial remission (CR or PR); stable disease (SD) or progression was considered as no HR. All statistical tests were 2-sided X2 t test and P values less than .05 were considered to be statistically significant. Results Seventy seven pts were evaluated with a median age of 56 years (33-74). Clinical characteristics are seen in Table 1. Only 18/77 pts (23%) received induction therapy: Dexamethasone alone n=9, Cyclophosphamide and Prednisone n=2, Mel/Dex n=4, VAD n=2 and Melphalan and Prednisone n=1. TRM observed was 12% mainly due to congestive heart failure and sepsis. Complete HR was achieved in 38 cases (49%) and OR was seen in 59%. Among the most common complications to ASCT, febrile neutropenia was reported in 67%, transient renal impairment in 10% and congestive heart failure in 3%. Median OS was significantly lower for patients with B-type natriuretic peptide (BNP) >300 pg/ml (17.7 vs 64.46 months) (p0.0004), Troponin I >0.07 ng/ml (19.25 vs 97.4 months) (p0.00001) and those who achieved a complete HR (115 vs 88 months) (p0.0345). Multivariate Cox regression analysis showed that BNP>300 pg/ml and Troponin I >0.07 ng/ml (normal <0.07) were the most important factors to predict OS for patients with AL who underwent ASCT (p0.0002 and 0.04 respectively). Conclusions Based on this study of 77 patients, clinical selection is the most important factor to better improve outcomes for HDM in AL. Patients with BNP>300 pg/ml and/or abnormal levels of Troponin I (>0.07) should not be considered eligible for transplants due to a high degree of mortality. Our series showed a CR rate of 49% which is higher than 33% reported by Palladini et al with Mel/Dex. Stringent case selection may be the most important factor in decreasing mortality rate associated to ASCT leading to better outcomes. Table 1. Clinical Characteristics of patients with AL Amyloidosis undergoing ASCT (at initial diagnosis) Clinical Characteristics N Median Range % Age (years) 77 57 33–74 Hemoglobin (g/L) 77 138 104–182 Creatinine (μ mol/L) 77 129 37–700 **BNP (pg/ml) 44 180 10–1670 ***BMPC (%)– 77 7 1–30 24 Hr Proteinuria (g/d) 77 5.5 0–24.9 Intraventricular Septal Distance (mm) 77 13 9–23 Kappa/lambda ratio 53 4.4 0.001–71.2 Kidney Involvement 71 Heart Involvement 52 Liver involvement 23 GI involvement 10 3 or more organs involved by AL 16 ** B-Type Natriuretic Peptide *** BMPC: Bone marrow plasma cells Disclosures: Stewart: Millennium: Consultancy; Celgene: Honoraria. Reece: Celgene: Honoraria, Research Funding. Chen: Celgene Corporation: Consultancy, Honoraria, Research Funding. Kukreti: Celgene: Honoraria.

Abstract Abstract 576 Stat3 appears to play a critical role in sustaining and generating memory B-cells and long-lived plasma cells (PCs) the normal counterparts of myeloma cells. In contrast to the transient nature of Stat3 activation in normal cells, many hematological tumors including multiple myeloma (MM) harbor constitutive Stat3 activity. Aberrant STAT signaling is recognized as a master regulator of direct and indirect tumor processes including proliferation, apoptosis, invasion, angiogenesis and cancer inflammation and thus Stat3 represents an important therapeutic target. Using structure-based design, targeting the phosphotyrosine (pY)-SH2 domain interactions that stabilizes active Stat3 dimers, phosphopeptides have been identified that block Stat3 dimerization and DNA binding activity. Peptidic agents however suffer from limited cell permeability and metabolic lability, properties that have restricted their practical application in vivo at therapeutic doses. Here we describe the dependence of myeloma tumors on Stat3 and characterize the anti-tumor activity of BP-2-047, a novel, non-phosphorylated small molecule with reduced peptidic character. We analyzed the activity of Stat3 using a Stat3 gene expression index based on Stat3 target genes in 60 human myeloma cell lines (HMCLs). Several available myeloma cell lines (XG6, XG7, JJN3 and UTMC2) demonstrated elevated STAT3 gene expression signatures (2.3 to 14.8) with confirmed constitutive Stat3 phosphorylation by Western blot analysis. RNA interference revealed that Stat3 is essential for XG6, JJN3, and UTMC2 survival. We similarly analyzed the activity of Stat3 in publicly available gene expression profile data sets derived from newly diagnosed MM patients. Approximately a third of patients demonstrated a functionally significant level of Stat3 signature, comparable to those in the Stat3-dependent cell lines. We next evaluated the anti-myeloma activity of the BP-2-047 in cell-based assays against a panel of HMCLs with high and low STAT3 activity. BP-2-047 delivered a desirable activity profile for targeted therapy. Consistent with its predicted mechanism of action, we observed dose-dependent inhibition of Tyr705Stat3 phosphorylation in XG6, XG7, JJN3 and UTMC2 cells, presumably through the blockade of Stat3 binding to the pTyr motifs of gp130 and the prevention of de novo phosphorylation by JAKs. Using a luciferase reporter assay we confirmed inhibition of Stat3 transcriptional activity in MM cells stably expressing the Stat3-dependent luciferase reporter (pLucTKS3). Inhibition of transcription was associated with decreased expression of short half-life proteins, c-Myc and Mcl-1. BP-2-047 inhibited viability of myeloma tumors with IC50 values of 3.1–7.4 microM, in cell lines with constitutive Stat3 activity. Inhibition of Stat3 phosphorylation resulted in induction of dose-dependent apoptosis as determined by PI/annexin V staining and PARP cleavage. However, cells were resistant to BP-2-047-induced apoptosis when co-cultured with bone marrow stroma cells. Identification of factors that confer survival advantage in the presence of stroma is in progress. Exposure of MM patient derived bone marrow mononuclear cells to < 15 microM BP-2-047 preferentially induced apoptosis of CD138 + MM cells. In contrast, BP-2-047 at concentrations of 30 microM failed to inhibit normal bone marrow-derived CD34 colony formation. In vitro combination studies in cell lines demonstrate synergy with dexamethasone, bortezomib and lenalidomide. Studies assessing in vivo activity of BP-2-047 as a single agent and in combination with bortezomib against Stat3 activated myeloma tumors in xenograft mice are ongoing and will be reported. These data suggest that Stat3 may represent an important therapeutic target in a subset of myeloma patients and supports innovative drug development with a focus on Stat3. Disclosures: No relevant conflicts of interest to declare.

Abstract Abstract 4034 Through literature review we identified 376 pre-clinical studies in which a small molecule or antibody has been demonstrated to be cytotoxic to multiple myeloma (MM) cells either as cell lines, primary tumor samples or in mouse models. Indeed it seems there is no limit to the number of compounds that are cytotoxic to MM cell lines at high enough concentration. Since the pipeline to clinical trials is then large the utility of such assays in predicting future clinical value is debatable. We therefore sought to examine the utility of applying very early Phase I or Phase II trial experiences to predict for future clinical adoption. Using Pubmed, ASCO, ASH, EHA and IMWG abstracts we identified 117 drugs explored as single agents in 211 early stage clinical MM trials between 1961 and 2012 involving 7,166 patients. As definitions have changed over time, our analysis used partial responses (PR) or better as a response. When multiple trials were reported with a single drug, the average and the highest response rate for that agent was identified. Results were considered regardless of whether single or multi center trial, elderly or younger patients, stage of disease, targeted or non targeted therapy. High dose therapies requiring autologous stem cell support (eg. melphalan and etoposide), trials with less then 5 patients (e.g. siltuximab) or trials with concomitant steroid application which obscure single agent activity (e.g. pomalidomide, marizomib or daratumumab) were excluded in the analysis. Results: 17 drugs (14.5%) showed a best result of PR in more than 20% of patients, but when average response across all reported trials is considered, doxorubicin, arsenic trioxide and idarubicin drop out leaving 14 active drugs. Twelve drugs (10.3%) report as a best result PR in 10–20% of patients. 88 drugs (75.2%) reported a PR response in less than 10% of patients, 68 of which (58.1%) had no reported activity. A striking finding of our study is that all drugs approved for, or commonly used in clinical practice (prednisone, dexamethasone, cyclophosphamide, melphalan, bendamustine, thalidomide, lenalidomide, bortezomib, carfilzomib) have an average single agent PR response of at least 20%. Pomalidomide, although not approved, meets this threshold in Phase I testing. Older agents including teniposide, fotemustine, paclitaxel, and interferon also appear active by this criteria but have fallen from favor or were never adopted due to perceived toxicity. Of note, a number of newer agents which are in, or which recently completed Phase 3 testing, such MLN9708, elotuzumab, panobinostat, vorinostat or perifosine show little single agent activity. A weakness in this approach is that changes in measurement of response over time might bias the results, especially in favor of older studies. Furthermore, the chance of responding to a new drug has likely slowly declined as therapies have improved and patients have entered such trials at increasingly late stages of disease. It also does not rule out the possibility of synergistic activity or clinical benefit from a cytostatic drug. Nevertheless, our analysis suggests that a cut off of 20% single agent partial response activity averaged across all trials with that agent is highly predictive of future clinical success. If best reported response over 20% is considered no drug except vincristine has yet reached the clinic and has subsequently fallen from favor. Thus only drugs with 20% PR activity are in widespread use and thus this benchmark provides a framework for guiding choice of drugs for late stage clinical testing. Disclosures: Jimenez-Zepeda: MMRF: Research Funding; Jansenn Ortho: Honoraria. Fonseca:Onyx: Consultancy, Research Funding; Cylene: Research Funding; Medtronic: Consultancy; Otsuka: Consultancy; Celgene: Consultancy; Genzyme: Consultancy; BMS: Consultancy; Lilly: Consultancy; Binding Site: Consultancy; Millenium: Consultancy; AMGEN: Consultancy; Mayo Clinic: Patents & Royalties. Stewart:Millenium: Consultancy, Honoraria, Research Funding; Onyx: Consultancy; Celgene: Consultancy.

Abstract The oncolytic reovirus (RV) has demonstrated clinical efficacy and minimal toxicity in a variety of cancers, including multiple myeloma (MM). MM is a malignancy of plasma cells that is considered treatable but incurable because of the 90% relapse rate that is primarily from drug resistance. The systemic nature of MM and the antitumor immunosuppression by its tumor microenvironment presents an ongoing therapeutic challenge. In the present study, we demonstrate that RV synergizes with the standard-of-care MM drug bortezomib (BTZ) and, importantly, enhances its therapeutic potential in therapy-resistant human MM cell lines in vitro. Using the syngeneic Vk*MYC BTZ-resistant immunocompetent transplantable MM murine model, we also demonstrate that mice harboring BTZ-insensitive MM tumors respond to the RV/BTZ combination treatment in terms of decreased tumor burden and improved overall survival (P &lt; .00001). We demonstrate that BTZ augments RV replication in tumor-associated endothelial cells and myeloma cells, leading to enhanced viral delivery and thereby stimulating cytokine release, immune activity, apoptosis, and reduction of the MM-associated immune suppression. We conclude that combined RV/BTZ is an attractive therapeutic strategy with no safety signals for the treatment of MM.

AbstractImmunoglobulin light chain (AL) amyloidosis is a fatal complication of B‐cell proliferation secondary to deposition of amyloid fibrils in various organs. Urinary exosomes (UEX) are the smallest of the microvesicles excreted in the urine. Previously, we found UEX of patients with AL amyloidosis contained immunoglobulin light chain (LC) oligomers that patients with multiple myeloma did not have. To further explore the role of the LC oligomers, UEX was isolated from an AL amyloidosis patient with progressive renal disease despite achieving a complete response. LC oligomers were identified. Mass spectrometry (MS) of the UEX and serum identified two monoclonal lambda LCs. Proteomics of the trypsin digested amyloid fragments in the kidney by laser microdissection and MS analysis identified a λ6 LC. The cDNA from plasma cell clone was from the IGLV‐ 6‐57 family and it matched the amino acid sequences of the amyloid peptides. The predicted mass of the peptide product of the cDNA matched the mass of one of the two LCs identified in the UEX and serum. UEX combined with MS were able to identify 2 monoclonal lambda LCs that current clinical methods could not. It also identified the amyloidogenic LC which holds potential for response assessment in the future.

SummaryThis single institution, open label Phase I‐II dose escalation trial evaluated the safety and efficacy of the combination of lenalidomide (Revlimid®), cyclophosphamide and prednisone (CPR) in patients with relapsed/refractory multiple myeloma. The maximal administered dose of CPR consisted of cyclophosphamide 300 mg/m2 on day 1, 8, and 15, lenalidomide 25 mg on d 1–21 and prednisone 100 mg every other day in a 28‐d cycle. Between November 2007 and June 2009, 32 patients were entered in cohorts of three at three dose levels. The median age was 64 years, 59% were male, with a median two prior regimens. Responding patients could stay on treatment until progression. The full‐dose CPR regimen produced no dose‐limiting toxicity and was delivered for a median of 16 months (3·5–65 months) with acceptable safety and tolerance. The overall response rate (≥ partial response) was 94% at a median follow up of 28 months. The median progression‐free survival was 16·1 months [95% confidence interval (CI); 10·9–22·5 months], while the median overall survival was 27·6 months (95% CI; 16·8–36·6 months). Only the beta‐2 microglobulin level at protocol entry correlated with a better survival (P = 0·047). These observations compare favourably with other 2‐ and 3‐ drug combinations for relapsed/refractory myeloma, and suggest that CPR should be evaluated further in the setting of relapsed/refractory disease, or in newly diagnosed patients.