Citations

Abstract Background: In order to understand the genetic events associated with disease progression and the development of drug resistance in multiple myeloma, we studied four longitudinally collected samples from a single, high risk, t(4;14) multiple myeloma patient. Samples over a four-year period were available from diagnosis, at time of first progression on lenalidomide, second progression while on bortezomib, at time of relapsed refractory disease and with end stage plasma cell leukemia. To better understand these genetic events, we utilized DNA extracted from germline tissue and CD138 purified bone marrow tumor cells to conduct whole genome sequencing (WGS) utilizing the Life Technologies SOLiD™ platform. Results: We have sequenced over 100 billion bases per sample with whole genome fragment library sequencing providing an average of 30X aligned coverage at all four time points studied. Each sample was aligned to the reference genome (NCBI36/hg18) with BFAST and post-alignment removal of duplicates and recalibration performed with Picard and Genome Analysis Toolkit (GATK) respectively. We then called point mutations with SolSNP and compared the germline sample to each tumor sample utilizing the Paired Mutation Walker. To date, we have identified 224 nonsynonymous point mutations within 217 genes. We then utilized the Sorting Intolerant from Tolerant (SIFT) algorithm and identified 109 potentially damaging point mutations which include 108 novel mutations in coding exons. Of the 224 somatic mutations observed, only 20 of these mutations are common to all tumor time points. Interestingly, the diagnostic and bortezomib refractory (second progression) samples had 11 mutations in common while the lenalidomide refractory (first progression) sample shared only 4 mutations in common with the bortezomib refractory sample. This suggests the presence of multiple clones at diagnosis that, due to treatment selection pressure, may emerge or regress as the dominant clone. Preliminary pathway analysis reveals the presence of mutations in genes regulating NFKB and Akt, whose pathways are often dysregulated in cancer. Conclusions: Whole genome sequencing has revealed evidence of mutational differences in exons between tumor and germline DNA indicative of the presence of multiple clones at diagnosis and evolution of these clones over time. This data supports the use of multiple drug therapies that target multiple clones and challenges the long held assumption that a patient who becomes refractory to a particular treatment will always be refractory to that treatment. Additional evaluation in a larger population is needed to confirm these findings. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4838. doi:10.1158/1538-7445.AM2011-4838

Abstract Multiple Myeloma (MM) is an incurable plasma-cell disorder progressing from indolent monoclonal gammopathy of undetermined significance (MGUS) and smoldering myeloma (SMM) to relapse MM and finally plasma cell leukemia (PCL). Alterations affecting TP53 are among the principal genetic progression events associated with disease progression. We analyzed results from gene expression profiling (GEP), array-based comparative genomic hybridization (aCGH), fluorescent in situ hybridization (FISH) and mutational data on the largest cohort published to date of 806 patients from all MM stages and 48 human myeloma cell lines (HMCLs). The prevalence of monoallelic TP53 deletions by aCGH is 1.4%, 3.7%, 8.9% and 25%, in MGUS, SMM, newly diagnosed and relapsed MM respectively. It reaches 53% in HMCLs and 75% in secondary PCL. No biallelic TP53 deletion were observed in patients and only 8% in HMCLs. In relapsed MM, the prevalence of TP53 deletions increases from 12/75 patients (16%) at first, to 9/31 patients (29%) in second and 5/7 patients (71%) in third relapse or more. We studied by FISH the status of TP53 in 113 patients from early stages progressing to relapse. Overall 15/113 patients had TP53 deletion, we confirmed that 10/15 patients acquired TP53 deletion at late stages. Next, we investigated the mutational status of TP53 in 59 relapsed MM patients, 5/59 samples (8.5%) had TP53 mutations, 4/5 mutations were located in the DNA binding domain. Presence of TP53 deletion conferred poor overall survival in relapsed MM patients (4.2 vs. 37.8 months, p = 0.015). A cohort of 239 patients had GEP-aCGH paired analysis we used a validated 70-gene model to stratify patients based on calculations obtained by GEP. The cohort was divided into quartiles and we observed the prevalence of TP53 in the low and high-risk groups. TP53 deletion was observed in 33/239 patients (14%) by aCGH, 2/33 (6%) had GEP values in the low-risk and 13/33 (39%) in the high-risk group. Next, we used a previously proposed cut-off value predicting TP53 deletion when GEP values are less than 733. We tried to validate this value as a surrogate for direct detection of TP53 deletion, and used the positive predictive value (PPV) of such level as a potential clinically useful marker. The fact that aCGH is the gold standard approach to define copy-number alterations, the proposed cut-off value failed to predict TP53 deletion as the PPV was low at 18% and the sensitivity of 69%. Finally, we studied by aCGH the status of MDM2 and CDKN2A, two key regulators of TP53. MDM2 gain and CDKN2A loss were infrequent events in patients even in advanced disease. In 48 HMCLs, only one had MDM2 copy gain (2%) while 14 cell lines had CDKN2A loss (29%). In MM, emergence of TP53 deletion/mutations in MM and its increase in aggressive stages of disease remain the overriding genetic factor for poor prognosis determination and a marker of progressive genetic events. Based on GEP, the 733 cut-off value did not accurately predict TP53 deletion. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 219. doi:10.1158/1538-7445.AM2011-219

Abstract Introduction:The histone deacetylase inhibitor (HDACi) Panobinostat (LBH-589, Novartis Pharmaceutical Corp) belongs to a new class of chemotherapeutics with demonstrated anticancer activities in laboratory studies and within the clinic. Using pre-clinical models of leukemia and lymphoma we have demonstrated that HDACi mediate their therapeutic effects via the intrinsic apoptosis pathway. Here we investigated the ability of Panobinostat to induce apoptosis in human multiple myeloma (MM) cell lines, alone and in combination with agents that target pro-survival Bcl-2 proteins (ABT-737) and the extrinsic apoptosis pathway (rhTRAIL). Moreover, we have used the Vk*myc murine model of MM to demonstrate the therapeutic efficacy of Panobinostat and its ability to induce apoptosis in MM cells in vivo. Methods: JJN3, OPM-2, RPMI-8226 and U266 MM cell lines were incubated with Panobinostat, ABT-737 or rhTRAIL alone or in combination. Cell viability and cell cycle were assessed using flow cytometry. Histone acetylation was assessed by western blot. C57BL/6 mice (n = 32) bearing transplanted Vk*myc MM (2 months post-transplant) were treated with Panobinostat (25mg/kg, 4 days; 15mg/kg 5 days/week, 3 weeks) or vehicle (D5W). Serum paraprotein levels were assessed weekly in all mice. Mice were sacrificed at various time points to measure apoptotic and therapeutic effects. Results: Treatment of MM cell lines with Panobinostat resulted in time- and dose-dependent induction of apoptosis associated with G1 phase arrest and histone H3/H4 acetylation. Combinations of Panobinostat with ABT-737 or rhTRAIL synergised to mediate robust and rapid apoptosis in the human MM cells. Serum paraprotein in mice bearing Vk*myc MM cells was significantly reduced after 4 days of high dose (25mg/ml) Panobinostat compared with vehicle treated mice (p<0.01) and remained at this reduced level for the treatment period (≤60% reduction compared with vehicle treated mice). This was associated with a significant induction of apoptosis and a reduction in CD-138+ plasma cells within the bone marrow. Removal of treatment was associated with increased paraprotein levels, progression of extramedullary disease and death endpoints. Overall, Panobinostat induced a significant survival advantage compared with vehicle (median=36.5 vs. 16 days, p<0.01). Conclusions: These results suggest that the HDACi Panobinostat has single agent activity against MM cell lines in vitro and provides a significant therapeutic benefit to mice bearing syngeneic MM tumors. Moreover, combination therapies consisting of HDAC inhibitors with agents that target pro-survival Bcl-2 proteins or the TRAIL apoptosis pathway may provide a rational approach to the treatment of MM. Future studies will investigate the molecular events underpinning the effects mediated by Panobinostat, ABT-737 and TRAIL in the Vk*myc MM model. Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B176.

Abstract The longitudinal evolution of a myeloma genome from diagnosis to plasma cell leukemia has not previously been reported. We used whole-genome sequencing (WGS) on 4 purified tumor samples and patient germline DNA drawn over a 5-year period in a t(4;14) multiple myeloma patient. Tumor samples were acquired at diagnosis, first relapse, second relapse, and end-stage secondary plasma cell leukemia (sPCL). In addition to the t(4;14), all tumor time points also shared 10 common single-nucleotide variants (SNVs) on WGS comprising shared initiating events. Interestingly, we observed genomic sequence variants that waxed and waned with time in progressive tumors, suggesting the presence of multiple independent, yet related, clones at diagnosis that rose and fell in dominance. Five newly acquired SNVs, including truncating mutations of RB1 and ZKSCAN3, were observed only in the final sPCL sample suggesting leukemic transformation events. This longitudinal WGS characterization of the natural history of a high-risk myeloma patient demonstrated tumor heterogeneity at diagnosis with shifting dominance of tumor clones over time and has also identified potential mutations contributing to myelomagenesis as well as transformation from myeloma to overt extramedullary disease such as sPCL.

Abstract Light-chain (AL) amyloidosis remains incurable despite recent therapeutic advances. Given the activity of the lenalidomide-alkylating agent combination in myeloma, we designed this phase 2 trial of lenalidomide, cyclophosphamide, and dexamethasone in AL amyloidosis. Thirty-five patients, including 24 previously untreated, were enrolled. Nearly one-half of the patients had cardiac stage III disease and 28% had ≥ 3 organs involved. The overall hematologic response (≥ partial response [PR]) rate was 60%, including 40% with very-good partial response or better. Using serum-free light chain for assessing response, 77% of patients had a hematologic response. Organ responses were seen in 29% of patients and were limited to those with a hematologic response. The median hematologic progression-free survival was 28.3 months, and the median overall survival was 37.8 months. Hematologic toxicity was the predominant adverse event, followed by fatigue, edema, and gastrointestinal symptoms. A grade 3 or higher toxicity occurred in 26 patients (74%) including ≥ grade 3 hematologic toxicity in 16 patients (46%) and ≥ grade 3 nonhematologic toxicity in 25 patients (71%). Seven patients (20%) died on study, primarily because of advanced disease. Lenalidomide, cyclophosphamide, and dexamethasone (CRd) is an effective combination for treatment of AL amyloidosis and leads to durable hematologic responses as well as organ responses with manageable toxicity. The trial was registered at www.clinicaltrials.gov (NCT00564889).

Abstract Emerging evidence indicates that tumors can follow several evolutionary paths over a patient's disease course. With the use of serial genomic analysis of samples collected at different points during the disease course of 28 patients with multiple myeloma, we found that the genomes of standard-risk patients show few changes over time, whereas those of cytogenetically high-risk patients show significantly more changes over time. The results indicate the existence of 3 temporal tumor types, which can either be genetically stable, linearly evolving, or heterogeneous clonal mixtures with shifting predominant clones. A detailed analysis of one high-risk patient sampled at 7 time points over the entire disease course identified 2 competing subclones that alternate in a back and forth manner for dominance with therapy until one clone underwent a dramatic linear evolution. With the use of the Vk*MYC genetically engineered mouse model of myeloma we modeled this competition between subclones for predominance occurring spontaneously and with therapeutic selection.

Abstract Immunoglobulin light-chain (AL) amyloidosis is a rare, incurable plasma cell disorder. Its therapy has benefited immensely from the expanding drug armamentarium available for multiple myeloma. Pomalidomide in combination with weekly dexamethasone (Pom/dex) is active among patients with relapsed myeloma. In the present study, we explored the Pom/dex combination in patients with previously treated AL. Patients were eligible for this prospective phase 2 trial if they had had at least one prior regimen and if they had reasonably preserved organ function. Patients were treated with oral Pom/dex. Thirty-three patients were enrolled. The median age was 66 years. Median time from diagnosis to on-study was 37 months. Eighty-two percent had cardiac involvement. The confirmed hematologic response rate was 48%, with a median time to response of 1.9 months. Organ improvement was documented in 5 patients. The median overall and progression-free survival rates were 28 and 14 months, respectively; the 1-year overall and progression-free survival rates were 76% and 59%, respectively. There was a discordance between the hematologic response and the N-terminal pro-brain natriuretic peptide response. The most common grade 3-5 adverse events, regardless of attribution, were neutropenia and fatigue. We conclude that pomalidomide appears to be a valuable drug covering an unmet clinical need in patients with previously treated AL. The trial is registered at www.clinicaltrials.gov as NCT00558896.

Abstract The attrition rate for anticancer drugs entering clinical trials is unacceptably high. For multiple myeloma (MM), we postulate that this is because of preclinical models that overemphasize the antiproliferative activity of drugs, and clinical trials performed in refractory end-stage patients. We validate the Vk*MYC transgenic mouse as a faithful model to predict single-agent drug activity in MM with a positive predictive value of 67% (4 of 6) for clinical activity, and a negative predictive value of 86% (6 of 7) for clinical inactivity. We identify 4 novel agents that should be prioritized for evaluation in clinical trials. Transplantation of Vk*MYC tumor cells into congenic mice selected for a more aggressive disease that models end-stage drug-resistant MM and responds only to combinations of drugs with single-agent activity in untreated Vk*MYC MM. We predict that combinations of standard agents, histone deacetylase inhibitors, bromodomain inhibitors, and hypoxia-activated prodrugs will demonstrate efficacy in the treatment of relapsed MM.

Abstract Cyclophosphamide, bortezomib, and dexamethasone (CyBorD) is highly effective in multiple myeloma. We treated patients with light chain amyloidosis (AL) before stem cell transplantation (ASCT), instead of ASCT in ineligible patients or as salvage. Treatment was a combination of bortezomib (1.5 mg/m2 weekly), cyclophosphamide (300 mg/m2 orally weekly), and dexamethasone (40 mg weekly). Seventeen patients received 2 to 6 cycles of CyBorD. Ten (58%) had symptomatic cardiac involvement, and 14 (82%) had 2 or more organs involved. Response occurred in 16 (94%), with 71% achieving complete hematologic response and 24% a partial response. Time to response was 2 months. Three patients originally not eligible for ASCT became eligible. CyBorD produces rapid and complete hematologic responses in the majority of patients with AL regardless of previous treatment or ASCT candidacy. It is well tolerated with few side effects. CyBorD warrants continued investigation as treatment for AL.

Abstract Maintaining results of successful induction therapy is an important goal in multiple myeloma. Here, members of the International Myeloma Working Group review the relevant data. Thalidomide maintenance therapy after autologous stem cell transplantation improved the quality of response and increased progression-free survival (PFS) significantly in all 6 studies and overall survival (OS) in 3 of them. In elderly patients, 2 trials showed a significant prolongation of PFS, but no improvement in OS. A meta-analysis revealed a significant risk reduction for PFS/event-free survival and death. The role of thalidomide maintenance after melphalan, prednisone, and thalidomide is not well established. Two trials with lenalidomide maintenance treatment after autologous stem cell transplantation and one study after conventional melphalan, prednisone, and lenalidomide induction therapy showed a significant risk reduction for PFS and an increase in OS in one of the transplant trials. Maintenance therapy with single-agent bortezomib or in combination with thalidomide or prednisone has been studied. One trial revealed a significantly increased OS with a bortezomib-based induction and bortezomib maintenance therapy compared with conventional induction and thalidomide maintenance treatment. Maintenance treatment can be associated with significant side effects, and none of the drugs evaluated is approved for maintenance therapy. Treatment decisions for individual patients must balance potential benefits and risks carefully, as a widely agreed-on standard is not established.