Citations

Abstract Immunoglobulin (Ig) light chain (LC)-associated amyloidosis (AL) is a fatal plasma cell (PC) disorder characterized by the overproduction of Ig light chains that deposit in an abnormal conformation as amyloid throughout the body. Lambda LC are involved in amyloid deposition 2–3 times more often than kappa LC, and certain LC Ig variable genes are more frequently involved than others and influence clinical presentation and outcome. AL is a potential complication of any immunoglobulin clonal process, but is most often pathologically associated with minimal clonal expansion of PC, as seen in monoclonal gammopathy of undetermined significance. It is much less commonly observed in patients with multiple myeloma (MM). Because of this, and to our knowledge, there are no cell lines that have been established from AL patients, an experimental tool that would be of great value in studying amyloid formation and the biology of amyloid producing PC. In this study, we have established two cell lines from a 50 yr old female initially diagnosed with AL. Upon initial diagnosis, the BM aspirate consisted of 27% IgG λPC with a PC labeling index (PCLI) of 1.9% and a κ to λratio of <0.1. Amyloid was present in periosteal vessel walls and in the fat aspirate. The first cell line, ALMC-1, was established from BM mononuclear cells isolated from the diagnostic aspirate. The patient received a peripheral blood stem cell transplant (PBSCT) 2 months later, but relapsed within 100 days post-PBSCT with symptomatic myeloma. At relapse, the patient’s BM aspirate consisted of 70% λ+ PC and a PCLI of 20%; the second cell line, ALMC-2 was established from this aspirate. IgVL and IgVH analysis revealed that both cell lines expressed identical sequences and used IgVλ 6–57*01, IgλJ3*02, and IgλC3*03: both used the IgVH VH3–21 gene and the extent of somatic mutation was approximately 4%. Both cell lines produce significant FLC, and studies are currently underway to characterize in vitro amyloid production. We next used fluorescence in situ hybridization (FISH) to identify the genetic defects in this patient’s tumor population before and after transition to symptomatic MM. The initial BM aspirate at time of diagnosis of AL revealed approximately 30% of the PC had clear evidence of c-MYC gene amplification. In the subsequent draws as well as in both cell lines, 100% c-MYC amplification was identified, consistent with clonal selection. FISH analysis also revealed that 40% of cells had p53 deletion upon initial diagnosis, whereas the subsequent samples and cell lines were 100% for p53 deletion. All cells also had an IgH translocation that did not involve any commonly observed chromosome partners. Lastly, we have characterized the cytokine responsiveness of both cell lines. Although some differences are observed between ALMC-1 and ALMC-2, IL-6 and IGF-1 stimulated growth in both cell lines to varying degrees and both lines expressed autocrine IGF-I. In summary, our initial characterization of ALMC-1 and ALMC-2 predicts that these unique cell lines will prove to be an invaluable tool to better understand AL, from the combined perspectives of amyloidogenic protein structure and amyloid formation, genetics, and cell biology. Insight gained from this model system may eventually have an impact in the clinical arena by providing a better understanding of this incurable disease.

Translocations involving immunoglobulin (Ig) loci and chromosome 13 monosomy (Δ13) are frequent cytogenetic findings in multiple myeloma (MM). Similar chromosomal aberrations have been identified in the monoclonal gammopathy of undetermined significance (MGUS), but their prevalence and significance remain uncertain. Bone marrow from 72 patients with MGUS (n = 62) and smoldering MM (n = 10) was evaluated for translocations between the Ig heavy chain (IgH) and chromosomes 4, 11, and 16, translocations involving Ig light chain–lambda (IgL-λ, and Δ13. Fluorescence in situ hybridization (FISH) analysis was done on clonal plasma cells (PCs) detected by immunofluorescence (cIg-FISH) of the cytoplasmic light chain. We also studied cells for cyclin D1 and FGFR3 up-regulation by immunohistochemistry and immunofluorescence, respectively. Twenty-seven (46%) of 59 patients had IgH translocations, and 4 (11%) of 37 had an IgL-λ translocation. A t(11;14)(q13;q32) was found in 15 (25%) of 59 patients, a t(4;14)(p16.3;q32) in 9% of patients, and a t(14;16)(q32;q23) in 5% of patients. All patients with t(4;14)(p16.3;q32) tested (n = 3) had intense cytoplasmic fluorescence with an anti-FGFR3 antibody. PC nuclear staining of cyclin D1 was only observed in patients with t(11;14)(q13;q32); Δ13 was detected in the clonal PCs in 50% of patients. The percentage of abnormal PCs varied with any given abnormality. No obvious clinical or biologic correlations were associated with these chromosome abnormalities. Similar translocations are found in both MGUS and MM, including t(4;14)(p16.3;q32) and t(14;16)(q32;q23). Moreover, Δ13 is common in MGUS and unlikely to play a predominant role in the evolution of MGUS to MM.

Abstract In an attempt to identify novel genetic abnormalities in multiple myeloma (MM) we analyzed 68 MM patient samples and 42 human myeloma cell lines (HMCL) with high-resolution (60kb) array-based comparative genomic hybridization (aCGH). We concentrated on bi-allelic genomic deletions with the expectation that these regions might contain novel tumor suppressor genes and identified a common abnormality at 14q32. Fine mapping of the 14q32 microdeletion by PCR demonstrated a 45 kb minimal deletion encompassing two genes; TRAF3, a negative regulator of the non-canonical NF-kB pathway, and AMN. To determine the frequency of copy number abnormalities of this region a cohort of 161 patients were screened with a FISH probe mapping to the minimally deleted region. This identified 7 (4.4%) patients with bi-allelic deletion and 19 (11.8%) patients with a single copy of the target region. Sequencing of all TRAF3 coding exons in 62 patients and 42 HMCL identified inactivating mutations in 9 patient samples and 4 HMCL. Overall, the incidence of TRAF3 inactivation, bi-allelic deletion or mutation, is 7/42 (16.7%) in HMCL and 12/62 (19.4%) in patients, making it one of the most common genetic abnormalities identified in MM. Importantly, dysregulation of NF-kB pathways is a common event in MM, but the mechanism for this dysregulation is largely unknown. Although TRAF3 is a negative regulator of the non-canonical NF-kB pathway it has not previously been implicated in cancer. Therefore, we tested the tumor suppressor function of TRAF3 by reintroducing TRAF3 into HMCL harboring TRAF3 abnormalities using an adenovirus gene transfer system. Expression of TRAF3 in HMCL with TRAF3 abnormalities rapidly reversed cellular processing of NFKB2 from p100 (an inactive isoform) to p52 (active) and additionally led to a 60% reduction in cellular proliferation (range, 10–89%) associated with Go/G1 cell cycle arrest and induction of cell death by apoptosis. At 48 hrs post infection the proportion of cells entering S-phase or G2/M declined by 31% (range, 8.1–56.1) and the proportion undergoing apoptosis increased by 28% (range 11.7–47.4%). In contrast, over-expression of TRAF3 in control HMCL without TRAF3 abnormalities had no effect. Overall, TRAF3 is identified as a novel tumor suppressor that regulates the non-canonical NF-kB pathway and is inactivated in ~ 20% of MM patients. Given the involvement of the NF-kB pathway in multiple human malignancies and the near constitutive expression of TRAF3 we propose that inactivation of TRAF3, a novel tumor suppressor identified for the first time in this study, may occur in other cancers. In this regard, we have recently identified a Burkitt lymphoma cell line that does not express TRAF3 and thus has constitutive processing of p100 to p52. The clinical and therapeutic consequences of this finding and its frequency in other tumor types are currently the focus of further investigation. In conclusion, the abnormalities identified in this study represent the first mutations identified that cause constitutive NF-kB activation in MM.

Abstract Plasma cell leukemia (PCL) is an aggressive and rare hematological malignancy that can originate either as primary disease (pPCL) or as a leukemic transformation of multiple myeloma (MMLT). We report here on the clinical characteristics, survival and genetic studies of 80 patients with PCL treated at a single institution (including 41 with pPCL and 39 with MMLT) and make comparisons with 439 newly diagnosed cases of multiple myeloma (MM). From our results pPCL presents a decade earlier than MMLT (54.7 vs 65.3 years) and despite substantially poorer clinical and laboratory parameters at presentation (hepatomegaly 32% vs 11%, leukocytes 31.6 vs 20.9, β2M 8.5 vs 4.3) pPCL appears more responsive to conventional combination chemotherapy (VAD, VBMVP or VBAP) than MMLT and is associated with significantly longer survival (median 18.4 vs 3 months). Comparison of pPCL groups treated with combination chemotherapy (n=21) or with other regimens (40% MP, 10% Thal/Dex, 20% other, 30% none)(n=20) identifies no substantial pre-treatment differences between the groups although a higher proportion of patients who received combination chemotherapy subsequently proceeded to stem cell transplantation (30 vs 10%). Importantly, survival of pPCL patients treated initially with combination chemotherapy (median 13.9, mean 27.3 months) was significantly longer compared with patients who did not receive combination chemotherapy (median 5.2, mean 9.9 months)(p=0.035) with 2 long term survivors (> 7 years) in the chemotherapy group. By comparison, patients with MMLT received less active therapy for their leukemic disease than did patients with pPCL (21% VAD, VBMVP or VBAP; 18% MP). Treated MMLT patients showed selection bias for younger age (60.9 vs 66.4 years) and lack of bone disease (0 vs 65%)(p<0.01); however despite this, median survival was disappointingly short for MMLT patients in the treatment group and was not significantly improved compared with non-treated patients (2.3 vs 0.8 months)(p=0.34). Assessment of novel therapies in PCL is therefore urgently required. Karyotype analysis and targeted genetic studies demonstrate that IgH translocations are present with high frequency in both pPCL and MMLT (71 vs 86%) compared with MM (~50%). Notably, IgH translocation in pPCL is almost exclusively targeted at chromosome 11 (cyclin D1) belying its importance in establishing the phenotype. IgH translocation in MMLT is primarily to chromosome 11 [71%], but also targets chromosomes 4 (FGFR3/MMSET) [13%] and 16 (cMaf) [20%], recapitulating MM. Abnormalities of chromosomes 3,5,7,9,11,13,15 and 19 are present equally in all 3 disorders. Deletion of 17p13 (p53) shows strong selection pressure in the leukemias (pPCL 53.8%, MMLT 48.8%, MM 10.7%) and is complemented by p53 mutation (23%). Notably, pPCL tumors show lower rates of Ras mutation (12 vs 40%) and p14 (0 vs 31%) or p16 (25 vs 40%) promoter methylation than MMLT. Together these results therefore indicate that pPCL and MMLT are fundamentally different plasma cell disorders with distinctive biology, genetic abnormalities and treatment responses.

Abstract Background: Patients with early stage myeloma are typically observed without therapy until symptomatic disease occurs. We have reported early results of therapy with single-agent thalidomide as initial therapy for early stage multiple myeloma in an attempt to delay progression to symptomatic disease (Leukemia2003;17:775–9). We now report the long-term results of this phase II trial. Methods: Thirty-one patients with smoldering or indolent multiple myeloma were enrolled between April 1999–March 2002. All pts had bone marrow (BM) plasma cells >=10% and measurable disease defined as serum monoclonal (M) protein >=2gm/dL and/or urine M protein >=400mg/24 hours. Two patients were deemed ineligible because they were found to have received prior therapy for myeloma and were excluded from analysis. Thalidomide was initiated at a dose of 200 mg/day and increased as tolerated by 200 mg/day every 2 weeks to a maximum dose of 800 mg/day. The dose of thalidomide was decreased as needed to minimize toxicity. Treatment was continued until disease progression or serious toxicity, except for patients achieving less than a minor response (<25% paraprotein reduction) to therapy in whom therapy was stopped at one year. Response was defined as a decrease in serum and urine monoclonal (M) protein by 50% or higher. If the serum M protein was unmeasurable, a 90% or higher decrease in urine M protein was required. Responses need to be confirmed at least 4 weeks apart. Results: Ten patients (34%) had indolent myeloma, including 4 patients with lytic bone lesions, 3 patients with anemia (Hb <11gm/dL), and 3 patients with both anemia and lytic bone lesions. Median follow up of living patients is 5.6 years (range, 4.0–7.1 years). Of the twenty-nine eligible patients, ten (34%) had a partial response to therapy with at least 50% or greater reduction in serum and urine monoclonal (M) protein. Three patients are still on study and receiving therapy. The remaining have gone off-study: seven patients (27%)had progressive disease while on therapy; other reasons for ending study treatment included completed therapy per protocol (2 pts), patient refusal (2pts), toxicity (8 pts), alternate treatment (3 pts), other medical problems (1 pt), died on study (1 pt), and other (2 pts). The median time to progression (TTP) was 3.2 years (95% CI 2.1–5.6 yrs). Median progression free survival (PFS) was 3.0 yrs (95% CI 2.0–5.1 yrs). Median overall survival has not been reached; 5 year survival rate by the Kaplan Meier method is 60%. Major grade 3–4 non-hematologic adverse events at any time during therapy were noted in 34% of patients; this includes 14% with grade 4 toxicity. Grade 3–4 toxicities occurring in more than one patient include neuropathy (2 pts) and sinus bradycardia (2 pts). Conclusions: Thalidomide has activity in asymptomatic myeloma. This approach must be further tested in randomized trials to determine if the survival estimates are superior to observation. Given the activity of thalidomide, trials are also needed with lenalidomide.

Abstract The t[4;14] simultaneously deregulates fibroblast growth factor receptor 3 (FGFR3) and MMSET in 15% of patients (pts) with Multiple Myeloma (MM). Although oncogenic, FGFR3 expression is lost in ~25% of t[4;14] pts on gene expression profiling while MMSET is always retained. The t[4;14] is highly associated with poor prognosis, furthermore FGFR3 kinase inhibitors are in Phase I trials, thus detection of t[4;14] pts is increasingly important. The Multiple Myeloma Research Consortium (MMRC) therefore evaluated 4 competing methodologies for the diagnostic detection of t[4;14]. Bone marrow (BM) samples were collected in uniform fashion from 85 pts. FGFR3 immunocytochemistry (ICC) and flow cytometry (FC) were performed at the retrieval site, while split samples were shipped to the MMRC tissue bank and processed under GLP conditions. Processed samples were analyzed by cIg-FISH and quantitative IgH-MMSET RT-PCR (QPCR) on unsorted BM and blood. Of 60 samples with sufficient plasma cells for analysis, 8 were FISH +ve [13.3%]. Low % BM plasma cells prevented successful FISH in 25% of samples reflecting large volume harvests and hemodilution. Analysis was conducted in a blinded fashion. With FISH as the gold standard for detection of t[4;14] the sensitivity and specificity of the other diagnostic tests are: BM QPCR is most sensitive (7 of 8 FISH positive detected) and specific (42/43 negatives correctly identified). QPCR on peripheral blood is ongoing. FC is more sensitive to the detection of FGFR3 protein than ICC. Correlation between FC and ICC was only 0.46. Interestingly, 6 of 7 evaluable pts here and 13/14 (92%) in an expanded analysis of FISH +ve patients also expressed the FGFR3 protein. Given the discrepancy between this finding and previously reported loss of FGFR3 expression in 25% of pts we further explored t[4;14] stability. Clonal selection/heterogeneity was determined by the % plasma cells in each pt. with an unbalanced translocation (loss of one der chromosome). In 42 t[4;14] pts, 13 (31%) had a balanced translocation(>75% of cells with a double fusion), 14 (33%) had an unbalanced translocation (>75% cells with only one signal), and 15 (36%) had a chimeric picture. This heterogeneous pattern is suggestive of an evolution towards an unbalanced translocation. Despite this survival did not differ between pts with balanced or unbalanced translocation. Conclusions: These results indicate that the t[4;14] is highly heterogeneous with respect to balanced versus unbalanced translocations, which likely evolve over time. For detection, cIg-FISH continues to be the gold standard diagnostic methodology but may be limited by low plasma cell numbers in dilute BM or during MM remission. QPCR and FC appear most sensitive and specific for presence of t[4;14] and FGFR3 protein expression respectively. Surprisingly (given prior evidence of loss of FGFR3 expression in 25% of pts) 92% of t[4;14] pts in this series expressed FGFR3 protein. # Analyzed % Positive Sensitivity Specificity FISH 60 13 - - QPCR 65 14 87.5 97.6 Flow 82 15 85.7 91 ICC 85 15 62.5 92

Abstract Introduction A unique biological characteristic of MM plasma cells (PCs) is the substantial production of immunoglobulin proteins. This process requires disulfide bond formations that in turn generate large amounts of H2O2. The Trx-TrxR reductase system exists to combat this oxidative stress; however, cytotoxicity can occur when the cells' antioxidative capacity is overwhelmed. Recently, we demonstrated that IMiDs inhibit peroxidase-mediated decomposition of H2O2, and that lenalidomide sensitivity in MM correlates with the degree of antioxidative capacity (Sebastian et al. 2015 ASH). In this study we sought to better understand this inhibitory process. Methods We used various human MM cell lines with different sensitivity to lenalidomide. Cell viability was assessed by the MTT assay. Antioxidative capacity was measured via the total cellular oxidation of reduced flavin adenine dinucleotide (FADH2) and reduced nicotinamide adenine dinucleotide (NAD(P)H) after H2O2treatment. A CRBN CRISPR/Cas9 KO plasmid was used to generate CRBN knockout cells and lentivirus system was used to over-express CRBN in MM cells. Results We found that IMiDs inhibit TrxR mediated intracellular H₂O₂ decomposition in a CRBN dependent fashion. Unlike lenalidomide, the direct TrxR inhibitor auranofin was very effective in inducing cell death in MM cell lines, in a CRBN independent fashion. By using MM.1R isogeneic cells with and without CRBN, and the CRBN-overexpressing OCIMY-5 cell line (transfected with wt-CRBN) we showed that auranofin treatment caused cytotoxicity irrespective of CRBN level of expression, while lenalidomide was only effective in CRBN expressing cells. Clinically achievable concentrations of auranofin treatment induced cell signals similar to lenalidomide, including degradation of IKZF1, IKZF3. As with lenalidomide, the sensitivity of CRBN expressing cell lines to auranofin correlated with their basal antioxidative capacity (MM.1S cells are sensitive and have with lower anti-oxidative capacity while RPMI-8226 is resistant due to its high anti-oxidative capacity). We also found that targeting Trx (downstream effector of TrxR) with the direct inhibitor PX12 overcame this cellular anti-oxidative capacity and inhibited cell proliferation in both RPMI-8226 and MM.1S in a CRBN independent fashion. Combination of auranofin with bortezomib showed a synergistic effect, but only in cells with lower anti-oxidative capacity. In contrast, PX-12, showed a synergistic effect with bortezomib in all analyzed MM cells lines, irrespective of their anti-oxidative capacity and CRBN expression. Conclusions IMiDs inhibit TrxR-mediated intracellular H2O2decomposition in CRBN expressing MM. While the direct TrxR inhibitor, auranofin, bypassed the CRBN requirement for inducing cytotoxicity in MM, its cytotoxic effect could be overcome by the cells antioxidative capacity. Direct Trx inhibition (such as PX-12) seems like a potent strategy for MM therapy to overcome cellular CRBN requirements and higher anti-oxidative capacity cells. Disclosures Bergsagel: Novartis: Research Funding; Amgen, BMS, Novartis, Incyte: Consultancy. Stewart:celgene: Consultancy. Fonseca:Patent Pending: Patents & Royalties: The use of calcium isotopes as biomarkers for bone metabolisms; Patent Pending: Patents & Royalties: The use of calcium isotopes as biomarkers for bone metabolisms; Janssen: Consultancy; Bayer: Consultancy; Millennium, a Takeda Company: Consultancy; Millennium, a Takeda Company: Consultancy; BMS: Consultancy; Millennium, a Takeda Company: Consultancy; Patent: Patents & Royalties: Prognostication of MM based on genetic categorization of FISH of the disease; Celgene: Consultancy; AMGEN: Consultancy; Patent: Patents & Royalties: Prognostication of MM based on genetic categorization of FISH of the disease; Millennium, a Takeda Company: Consultancy; Novartis: Consultancy; Celgene: Consultancy; Patent: Patents & Royalties: Prognostication of MM based on genetic categorization of FISH of the disease; Janssen: Consultancy; Patent: Patents & Royalties: Prognostication of MM based on genetic categorization of FISH of the disease; Bayer: Consultancy; AMGEN: Consultancy; Patent Pending: Patents & Royalties: The use of calcium isotopes as biomarkers for bone metabolisms; Novartis: Consultancy; AMGEN: Consultancy; Sanofi: Consultancy; AMGEN: Consultancy; Sanofi: Consultancy; BMS: Consultancy; Patent Pending: Patents & Royalties: The use of calcium isotopes as biomarkers for bone metabolisms.

Abstract Sequencing studies have significantly improved our understanding of the CLL genetic landscape and allowed the identification of the first associations between specific mutations and clinical outcome. Hence, mutations in TP53, NOTCH1, SF3B1, BIRC3 and MYD88 are known to be associated with differential prognosis and have been incorporated in CLL risk stratification models. Despite the work performed on these 5 genes, several additional putative tumor-driver genes are recurrently mutated in CLL, but their clinical impact remains unclear. In order to gain further understanding, we performed targeted sequencing in baseline samples of 308 CLL patients (pts) participating in the North American Intergroup study (NAIG) designated as E1912 and led by ECOG. This trial is a randomized Phase III of Ibrutinib (Ibr) and Rituximab (R) vs FCR in previously untreated CLL. Besides the 5 genes aforementioned, we screened another 19 genes recurrently mutated in CLL, and 2 genes (BTK and PLCy2) recently associated with Ibr resistance. The CD5+/CD19+ B lymphocyte population of these pts was flow-sorted. All coding regions were amplified using customized oligos. Libraries were templated and enriched using IonOneTouch2 and IonOneTouch ES systems, respectively. Samples were run on an IonTorrent sequencer using 318TM chips. Variants were called using IonTorrent Somatic VariantCaller. VCF files were annotated using BioR, which provides annotation from NCBI/Ensembl, UCSC, dbSNP, HapMap, 1000Genomes, COSMIC, SIFT, and PolyPhen-2. Somatic variants with a Mapping Quality <20 or read depth <5X were removed. Variants of interest were inspected using Integrative Genomics Viewer. The mutational status of genes and pathways was analyzed for association with chromosomal abnormalities detected by FISH, expression of CD38, CD49d and ZAP70, Rai stage, age and gender. We were not able to evaluate associations to clinical responses for the different arms as this trial is still underway and remains blinded for clinical outcome. We found 511 SNVs (442 missense, 45 nonsense and 24 splice sites) and 115 indels. An average coverage of 770X depth was obtained, allowing the detection of minor subclonal mutations (<10% of reads) in almost 35% (218/626 mutations). Overall, 215 pts (70%) carried at least one mutated gene, 102 (33%) carried 2 or more and 32 (10%) 3 or more mutated genes. The most commonly mutated gene was SF3B1 (22%), followed by NOTCH1 (19%), ATM (12%), XPO1 (11%), BIRC3 (9%), KRAS (7%), BRAF, DDX3X, EGR2, POT1 and TP53 (6% each). No BTK or PLCy2 mutations were found in progressive but untreated CLLs. In contrast to a recent report (Nature 2015;526:525-30), we found BRAF mutations located in the canonical hotspot p.V600E (25% of total mutations). Another 13% were located in amino acid K601 (p.K601E/N) and the remaining in the kinase domain (p.G469A, p.D594G, p.F595L, p.G596R, p.L597Q).Nearly 27% of cases with activating mutations in the RAS pathway (BRAF, KRAS, NRAS), showed >1 mutation affecting one or more genes of the pathway. Similar observations were found in mutational hotspots of BIRC3 (30% of mutated cases showed >1 mutation), MED12 (18%), SF3B1 (7%), XPO1 (6%), and NOTCH1 (5%), suggesting the existence of genetic subclones showing convergent evolution in a substantial number of CLL. We found multiple associations between mutations and known prognostic and clinical parameters. These included mutations in NOTCH1 associated with +12 (p=0.005), and expression of ZAP70 (p=0.01), CD38 (p=0.001) and CD49d (p=0.004). Mutant BIRC3 was associated with +12 (p<0.001) and CD38 expression (p=0.01). Mutations in RAS pathway, with +12 (<0.001), and expression of CD38 (p=0.002) and CD49d (p=0.05). ATM (p=0.007) and EGR2 (p=0.002) with -11q; POT1 with CD49d expression (p=0.01), and MYD88 with -13q (p=0.04) and lack of CD38 (p=0.01) and CD49d (p=0.01) expression. This study, performed on a large cohort of untreated but progressive CLLs, provides novel data about the mutation status of driver genes and their associations with clinical and prognostic parameters. Our data indicate that convergent evolution is a common event in CLL, affecting several driver genes. Furthermore, it reinforces that BTK and PLCy2 mutations are not found in Ibr-naive pts. Finally, this study provides the genetic groundwork for subsequent prospective comparative analyses of the clinical outcome for CLL cohorts treated with Ibr-R vs FCR in this phase 3 NAIG trial. Disclosures O'Brien: Janssen: Consultancy, Honoraria; Pharmacyclics, LLC, an AbbVie Company: Consultancy, Honoraria, Research Funding. Fonseca:Novartis: Consultancy; Patent Pending: Patents & Royalties: The use of calcium isotopes as biomarkers for bone metabolisms; Patent: Patents & Royalties: Prognostication of MM based on genetic categorization of FISH of the disease; Novartis: Consultancy; Janssen: Consultancy; BMS: Consultancy; AMGEN: Consultancy; Patent Pending: Patents & Royalties: The use of calcium isotopes as biomarkers for bone metabolisms; Patent: Patents & Royalties: Prognostication of MM based on genetic categorization of FISH of the disease; AMGEN: Consultancy; Millennium, a Takeda Company: Consultancy; Patent: Patents & Royalties: Prognostication of MM based on genetic categorization of FISH of the disease; Patent Pending: Patents & Royalties: The use of calcium isotopes as biomarkers for bone metabolisms; Sanofi: Consultancy; Celgene: Consultancy; Celgene: Consultancy; Bayer: Consultancy; Janssen: Consultancy; Millennium, a Takeda Company: Consultancy; Millennium, a Takeda Company: Consultancy; AMGEN: Consultancy; AMGEN: Consultancy; Bayer: Consultancy; BMS: Consultancy; Sanofi: Consultancy; Millennium, a Takeda Company: Consultancy; Patent: Patents & Royalties: Prognostication of MM based on genetic categorization of FISH of the disease; Patent Pending: Patents & Royalties: The use of calcium isotopes as biomarkers for bone metabolisms. Shanafelt:Genentech: Research Funding; Pharmacyclics: Research Funding; Celgene: Research Funding; GlaxoSmithkKine: Research Funding; Janssen: Research Funding; Cephalon: Research Funding; Hospira: Research Funding.

Abstract Abstract 1846 Background The low frequency of TP53 (p53) alterations (<10%) in MM makes this tumor an ideal candidate for p53-activation therapies. Unfortunately, DNA alkylating agents (cyclophosphamide and melphalan), when used alone, cannot fully exploit p53 mediated apoptosis. It is currently unknown the extent to which DNA alkylating agents and p53 activating small molecules are activating functional p53 signaling to induce apoptosis in primary MM cells, because, p53 mainly induces cell cycle arrest/DNA repair or apoptosis in the DNA damage response. Emerging studies demonstrate that PARP activation and p53 poly(ADP-ribosyl)ation can negatively influence apoptosis induction but the exact molecular mechanisms are unknown. Methods For apoptosis and gene expression analysis 05 × 106 cells were incubated with 2.5 μM of melphalan, 10 μM of olaparib and 2.5 μM of nutlin-3a alone and/or combinations of melphalan with olparib and/or nutlin3a with olaprib for 24 to 72 hours before they were examined for cell death by the annexin-PI and FACS analysis. Gene and protein expression were measured by RT-PCR, western blot, and immunohistochemistry. For combination studies, cells were incubated with 0.194–50 μM of melphalan and 0.625–40 μM of either olaparib or ABT-888 for 72 hours. p53 knock-down performed by lentiviral mediated shRNA. Vk*MYC mice with significant gammopathy (>20g/l on SPEP) used for in-vivo drug combination studies. Results Preliminary results support our principle hypothesis that, a PARP inhibitor (olaparib) enhanced Melphalan sensitivity in wild type p53 MM cell lines H929 and MM1S but not in p53 mutated or homozygously deleted cell lines U266 and KMS11, respectively. Moreover, we demonstrate that p53 knock-down decreased the synergistic effect of combining a PARP inhibitor with melphalan and Nutlin-3a. Again, combining a PARP inhibitor with the DNA alkylating agent melphalan induced clear PARP cleavage, a signature of apoptosis in wild type p53 MM cell lines H929 and MM1S. No significant PARP cleavage was observed after melphalan or olaparib treatment alone in H929 and MMIS. As expected, the p53 mutant cell line U266 did not show any PARP cleavage and p21 up-regulation after both drug treatments. Here we propose that the hyper-activated p53 from PARP inhibition along with DNA alkylating agents (melphalan) and/or p53 activating agents (nutlin-3a) result in better responses. Finally, in a murine xenograft model of human MM, olaparib potentiated melphalan activity in vivo, with significant reduction in M spike level. Conclusion Our studies indicate that DNA alkylating agents activate wild type p53, but leads to DNA repair and cell survival and this can be abolished by PARP inhibition in wild type p53 expressing MM cases. Moreover, our study also found that olaparib, and ABT-888 - PARP1 inhibitors currently in clinical trials - display different dose responses in MM cell lines and in the abilities of individual PARP inhibitors to sensitize MM cell lines to melphalan varied to a great extent in a cell context- and cell line specific manner. Disclosures: No relevant conflicts of interest to declare.

Abstract Introduction: Hematologic response (HR) particularly complete response (CR) is critical in patients (pts) with AL since it improves overall survival (OS) because of organ response (OrgR). Bor based therapies especially in combination with cyclophosphamide and dexamethasone (CyBorD) have shown to be an active regimen in AL. So far, there have been no comparative studies studying the effect of treatment with B-based regimens prior to SCT (Bor-SCT) versus SCT upfront or SCT preceded by non-Bor therapies (non-Bor-SCT). We present a retrospective analysis of data with an aim to compare the OS, OrgR and HR in the two cohorts. Methods: Charts were reviewed for the pts who underwent SCT for AL since 2004 until 2015 at Mayo Clinic in Arizona. HR and OrgR were determined using the consensus criteria from International Society of Amyloidosis.1 HR were noted at 3, 6 and 12 months from SCT. Results: Patients and disease characteristics: 63 pts were identified who underwent SCT for AL, of which 34 were in Bor-SCT and 29 were in the non-Bor-SCT cohort. Median age at diagnosis was 59.5 (range, 39 - 72) and 63 (range, 38 - 76) years and at SCT was 60 (range, 40 - 72) and 63 (range, 39 - 76) years for Bor-SCT and non-Bor-SCT, respectively. There were 13 (38%) females in Bor-SCT and 9 (31%) in non-Bor-SCT. Mean bone marrow involvement of plasma cells at diagnosis was 18% (SD±16.5) in Bor-SCT and 6.8% (SD±7.8) in non-Bor-SCT (p = 0.004). All pts had an ECOG performance score of better than 3 at the time of SCT. Fifteen (44%) pts had single organ involvement at diagnosis and 9 (26.5%) had 2-organ involvement in Bor-SCT. In non-Bor-SCT, 21 (72%) pts had single and 6 (21%) had 2-organ involvement (p = 0.04). More than 2 organs were involved in 10 (29%) pts in Bor-SCT and 2 (7%) in non-Bor-SCT. Heart was involved in 18 (53%) pts in Bor-SCT and 8 (28%) in non-Bor-SCT (p = 0.04) while kidney involvement was seen in 27 (79%) in Bor-SCT and 23 (79%) in non-Bor-SCT (p = 0.99). Median creatinine was not significantly different in the 2 groups at diagnosis or at the time of SCT. In Bor-SCT, no pts were on hemodialysis at the time of diagnosis or SCT. In non-Bor-SCT, 1 pt at diagnosis and 3 pts at SCT progressed to need hemodialysis. Lambda light chain was involved in 27 (82%) and 22 (76%) (p = 0.56) with a mean level of involved light chains being 59(SD±88.7) g/dL and 43.3 (SD±64.6) g/dL (p=0.4539) in Bor-SCT and non-Bor-SCT, respectively. Treatment: Thirty-one (91%) out of 34 pts in Bor-SCT group got treatment with CyBorD while 2 (6%) got Bor with dexamethasone and 1 (3%) got Bor with pegylated liposomal doxorubicin. In the non-Bor-SCT group, 20 (69%) out of 29 got no treatment, 4 (14%) got melphalan prednisone, 2 (7%) got dexamethasone alone, 1 (3%) got vincristine dexamethasone and 2 (7%) got lenalidomide dexamethasone prior to SCT. Transplant factors: Median time from diagnosis to SCT was 226.5 (range, 65 - 1108) days in Bor-SCT and 150.5 (48 - 1139) days in non-Bor-SCT (p=0.32). Full dose of melphalan (200 mg/m2) was used in 21 (62%) pts in Bor-SCT and 13 (34%) pts in non-Bor-SCT (p <0.001). Mean dose of cells used for SCT was 4.6 (SD±0.9) and 4.8 (SD±2.2) x 106/kg in Bor-SCT and non-Bor-SCT, respectively. Median time to neutrophil and platelet engraftment was 13 (range, 10 - 27) and 16 (range, 8 - 28) days in Bor-SCT while 11 (range, 7 - 16) and 13 (range, 10 - 25) days in non-Bor-SCT. Responses: HR at 3, 6 and 12 months from SCT and OrgR by the time of last follow up is described in table 1. Survival: Median OS was not reached in Bor-SCT as compared to 53.4 months in non-Bor-SCT (p =0.001), Figure 1. Conclusions: Our study suggests a benefit in HR, OrgR as well as OS by reduction of disease burden by Bor-based therapy prior to SCT. This benefit was observed despite a higher percentage of pts with cardiac involvement, more than 2 organ involvement and mean bone marrow plasma cells at diagnosis in Bor-SCT. Currently, it is not standard practice to use Bor-based therapy prior to SCT. A prospective study with larger number of pts would be required to confirm these findings. References: 1. Gertz MA et al. Definition of Organ Involvement and Treatment Response in Immunoglobulin Light Chain Amyloidosis (AL): A Consensus Opinion From the 10th International Symposium on Amyloid and Amyloidosis. Am J Hematol. 2005;79(4):319-328. Disclosures Dueck: Bayer: Honoraria. Mikhael:Abbvie, Celgene, Onyx, Sanofi: Research Funding. Bergsagel:Amgen, BMS, Novartis, Incyte: Consultancy; Novartis: Research Funding. Reeder:Novartis, Millennium, BMS and Celgene: Research Funding. Stewart:celgene: Consultancy. Fonseca:AMGEN: Consultancy; Janssen: Consultancy; Novartis: Consultancy; Sanofi: Consultancy; Bayer: Consultancy; Millennium, a Takeda Company: Consultancy; Millennium, a Takeda Company: Consultancy; AMGEN: Consultancy; BMS: Consultancy; Celgene: Consultancy; Patent: Patents & Royalties: Prognostication of MM based on genetic categorization of FISH of the disease; Patent: Patents & Royalties: Prognostication of MM based on genetic categorization of FISH of the disease; Patent Pending: Patents & Royalties: The use of calcium isotopes as biomarkers for bone metabolisms; AMGEN: Consultancy; AMGEN: Consultancy; Patent: Patents & Royalties: Prognostication of MM based on genetic categorization of FISH of the disease; Patent Pending: Patents & Royalties: The use of calcium isotopes as biomarkers for bone metabolisms; Millennium, a Takeda Company: Consultancy; Sanofi: Consultancy; Janssen: Consultancy; Millennium, a Takeda Company: Consultancy; Patent: Patents & Royalties: Prognostication of MM based on genetic categorization of FISH of the disease; Patent Pending: Patents & Royalties: The use of calcium isotopes as biomarkers for bone metabolisms; Patent Pending: Patents & Royalties: The use of calcium isotopes as biomarkers for bone metabolisms; Celgene: Consultancy; BMS: Consultancy; Bayer: Consultancy; Novartis: Consultancy.