scholarly journals Novel Alkylating Agent Melflufen Displays Potent Efficacy in Plasma Cell Leukemia Samples and Other High-Risk Subtypes of Multiple Myeloma

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 12-13
Author(s):  
Beau M Idler ◽  
Olivia Perez De Acha ◽  
Owen Lockerbie ◽  
Ken Flanagan ◽  
Fredrik Lehmann ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Bone Marrow ◽  
High Risk ◽  
Plasma Cell ◽  
Research Funding ◽  
Ex Vivo ◽  
Plasma Cell Leukemia ◽  
Peptide Drug ◽  
Cell Leukemia ◽  
Plasma Cell Disorders

Introduction: Despite the progress that has been made for standard risk multiple myeloma (MM), subsets of patients with the most advanced and aggressive plasma cell dyscrasias still suffer comparatively poor outcomes. One example is plasma cell leukemia (PCL), which carries a median overall survival of under two years. For patients with PCL, response to front line therapy occurs but is often short-lived, ultimately giving way to aggressive multi-drug resistant disease and patient mortality. Thus, there is a need for the development of new strategies that improve the prognoses for these patients. Melflufen (melphalan flufenamide) is a first-in-class peptide-drug conjugate that is currently in late-phase clinical trials for multiple myeloma. This highly lipophilic agent is preferentially retained in malignant plasma cells (MPCs), where overexpressed aminopeptidases lead to trapping of the alkylator melphalan. We evaluated the anti-myeloma effects of melflufen on patient samples treated ex vivo, and found pronounced sensitivity to melflufen in most samples, with particularly potent efficacy in PCL samples. Methods: Bone marrow aspirate or peripheral blood samples were obtained from patients with plasma cell disorders after IRB approval and informed consent. Ex vivo efficacy of melflufen and melphalan were compared using our Myeloma Drug Sensitivity Testing (My-DST) platform that optimizes viability and tests the malignant cells in the context of the normal cells from their microenvironment (Walker et al, Blood Advances, 2020). In brief, mononuclear cells from patients with plasma cell dyscrasia, including MM and PCL, were isolated and cultured in triplicate wells with titrations of melphalan, melflufen or untreated controls for 48 hours. Post-treatment survival was measured by high-throughput flow cytometry with antibodies for CD138, CD38, CD45 and CD19, and a live/dead dye to discriminate viable MPCs from normal bone marrow cells. EC50 values were determined from these titrations using nonlinear regression curve fits. When the EC50 for melflufen was established in My-DST, a single dose concentration of 10 nM was used to screen patient samples and distinguish relative sensitivity or resistance. Results: Using the My-DST approach with 48 hour drug treatments, melflufen significantly decreased the viable MPC populations, whereas melphalan had little effect (Fig 1A). Concurrent titrations revealed significantly higher MPC sensitivity to melfufen (mean melphalan EC50 = not reached, mean melflufen EC50 = 22.9 nM) (Fig 1B). By comparison to another alkylator, cyclophosphamide's active metabolite has an EC50 of 3.75 µM in this assay. Response to melflufen was accentuated in 2/3 PCL samples tested (HTB-1802.1, HTB-1389.1), with the EC50 < 1nM (Fig 1B). Melflufen demonstrated toxicity in CD45 positive white blood cells, which is consistent with neutropenia observed in clinical trials (data not shown). In single dose screening studies in additional MM patient samples, 4/8 (50%) showed >20% decrease in viable MPCs after incubation with melflufen at 10 nM (Fig 1C). Overall, using those parameters for ex vivo "response" to meflufen, 3/3 patients with PCL responded, 5/6 patients with del(17p) responded, and 3/3 patients with c-MYC translocations responded (Fig 1C, italics). In addition, 3/5 samples from patients that were clinically daratumumab-refractory displayed sensitivity to melflufen. Of five samples from patients with prior exposure to alkylators, four were sensitive to melflufen. Conclusion: Overall, these data support that the peptide-drug-conjugate melflufen shows a broad efficacy across samples from patients with plasma cell disorders. Patients facing poor prognoses, including those with PCL, high-risk cytogenetics and daratumumab-refractory disease, have a great need for new treatments. Thus, the encouraging ex vivo results with melflufen in samples from these aggressive subsets support further clinical exploration. In particular, our preliminary data suggest that plasma cell leukemia patients may be exquisitely sensitive to melflufen. To follow-up these findings, we will expand the number of samples tested from PCL and other forms of high-risk MM samples. Ultimately, if the trend for accentuated sensitivity in plasma cell leukemia holds, a clinical approach for melflufen in these patients may improve outcomes for this group. Figure 1 Disclosures Lockerbie: Oncopeptides AB: Current Employment. Flanagan:Oncopeptides AB: Current Employment. Lehmann:Oncopeptides AB: Current Employment. Forsberg:Celgene: Speakers Bureau; Genentech, Inc., Sanofi, Karyopharm, Abbvie: Research Funding. Mark:Takeda: Consultancy; Kayopharm: Consultancy; Bristol-Myers Squibb: Research Funding; Janssen: Research Funding; Celgene: Consultancy; Amgen: Consultancy; Sanofi: Consultancy; Janssen: Consultancy. Sherbenou:Oncopeptides Inc.: Research Funding.

Differential Presence of Truncated Forms of Transcription Factor Yin Yang 1 (YY1) in Bone Marrow of Multiple Myeloma Patients.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 5083-5083
Author(s):  
Mehran S. Neshat ◽  
Haiming Chen ◽  
Melinda S. Gordon ◽  
James R. Berenson ◽  
Benjamin Bonavida
Keyword(s):  
Multiple Myeloma ◽  
Bone Marrow ◽  
Transcription Factor ◽  
Plasma Cell ◽  
Plasma Cell Leukemia ◽  
Transactivation Domain ◽  
Cell Leukemia ◽  
Yin Yang 1 ◽  
Yin Yang ◽  
And Function

Abstract The transcription factor Yin Yang 1 (YY1) regulates cellular differentiation and response to apoptotic stimuli. YY1 exerts its pleiotropic effects through regulation of promoter activity of critical genes, as well as association and direct modulation of stability and function of a subset of proteins. Genes that are regulated by YY1 include those that control the cell cycle, development, differentiation and tumor suppression. For example, it has been reported that YY1 inhibits the proto-oncoprotein c-Myc (Austen, et al., Oncogene, 1998, 17:511) and negatively regulates the tumor suppressor gene p53 (Sui, et al., 2004, Cell 117: 859). Thus, expression and activity of YY1 in tumor cells may be involved in the pathogenesis of disease, as well as controlling response to drug stimuli. YY1 is regulated at transcriptional and post-translational levels in response to intra and extracellular signals. It has been reported that YY1 undergoes proteolytic cleavage. Caspase-dependent N-terminal cleavage of YY1 has been reported in response to physiological (Fas, TNF, L-glutamate) and chemical (staurosporine, etoposide, okadaic acid) death promoting factors. Similar presence of truncated YY1 is observed in in vitro models of skeletal and cardiac muscle differentiation. N-terminal truncated YY1 lacks its transactivation domain, while DNA binding remains unaltered. Hence, YY1 function may be altered by truncated forms. We hypothesized that post-translational processing of YY1 occurs in bone marrow and may be important in tumor progression and response to therapeutic agents. This study thereby aimed to determine whether altered levels and/or forms of YY1 are expressed in the bone marrow of multiple myeloma patients and to identify their potential downstream effectors. YY1 expression in protein lysates of bone marrow aspirates from nine patients was determined by Western blot analysis. Truncated species of YY1 were present in 6/8 samples. In contrast to myeloma bone marrow, one plasma cell leukemia sample showed high levels of YY1 and no truncated forms. Similar high levels of YY1 expression was observed in established tumor xenografts of a plasma cell leukemia tumor. We are presently extending the pool of analyzed normal and cancer harboring tissues and examining potential correlation of YY1 and its altered forms with disease status and prior therapeutic history. Identification and purification of cell populations that generate altered forms of the protein and its effect on expression and function of YY1 interacting proteins are under investigation.

scholarly journals The Mutational Landscape of Primary Plasma Cell Leukemia

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 114-114 ◽  
Author(s):  
Carolina D. Schinke ◽  
Cody Ashby ◽  
Yan Wang ◽  
Ruslana G. Tytarenko ◽  
Eileen Boyle ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
High Risk ◽  
Board Of Directors ◽  
Plasma Cell ◽  
Research Funding ◽  
Cell Leukemia ◽  
Advisory Committees ◽  
Kras Mutations ◽  
Aggressive Disease ◽  
Primary Plasma Cell Leukemia

Abstract Introduction: Primary Plasma Cell Leukemia (pPCL) is a rare form of multiple myeloma (MM) that is characterized by an aggressive disease course with >20% peripherally circulating plasma cells (PCs) and poor clinical outcome. Despite the advances of modern anti-MM therapy, pPCL patients continue to experience low median overall survival (OS) suggesting a distinct biological background. Due to its low incidence of 1-2% of all MM patients, studies on physiopathology remain challenging and are limited. The aim of this study was to elucidate the differences in biology and outcome between non-pPCL MM and pPCL, to determine the genetic landscape of pPCL and to identify distinct signatures and pathways that potentially could be used as therapeutic targets. Methods: We performed gene expression profiling (GEP; Affymetrix U133 Plus 2.0) of matched circulating peripheral PCs and bone marrow (BM) PCs from 13 patients. Whole exome sequencing (WES) was performed on purified CD138+ PCs from BM aspirates from 19 pPCL patients with a median depth of 61x. CD34+ sorted cells, taken at the time of stem cell harvest from the same 19 patients, were used as controls. Translocations and mutations were called using Manta and Strelka and annotated as previously reported. Copy number was determined by Sequenza. Results: GEP from the BM and circulating peripheral PCs showed that the expression patterns of the two samples from each individual clustered together, indicating that circulating PCs and BM PCs in pPCL result from the same clone and are biologically clearly related. The clinical characteristics from the patient cohort used for WES analysis were as follows: median age was 58 years (range 36-77), females accounted for 74% (14/19), an elevated creatinine level was found in 78% (14/18) and an elevated LDH level in 71% (10/14). All patients presented with an ISS stage of III. Median OS of the whole dataset was poor at 22 months, which is consistent with OS from previously reported pPCL cohorts. Primary Immunoglobulin translocations were common and identified in 63% (12/19) of patients, including MAF translocations, which are known to carry high risk in 42% (8/19) of patients [t(14;16), 32% and t(14;20), 10%] followed by t(11;14) (16%) and t(4;14) (10%). Furthermore, 32% (6/19) of patients had at least one MYC translocation, which are known to play a crucial role in disease progression. MYC breakpoints (8q24) were identified in 25% with Ig partner loci including IGH (5%), IGK (10%), and IGL (10%). The remaining samples had partner loci including FAM46C (5%), MYNN (5%), SPARC (5%), QRSL1 (5%), RNF126 (5%), PLXNA4 (5%) and CDH7 (5%). The mutational burden of pPCL consisted of a median of 98 non-silent mutations per sample, suggesting that the mutational landscape of pPCL is highly complex and harbors more coding mutations than non-pPCL MM. Driver mutations, that previously have been described in non-pPCL MM showed a different prevalence and distribution in pPCL, including KRAS and TP53 with 47% (9/19) and 37% (7/19) affected patients respectively compared to 21% and 5% in non-PCL MM. PIK3CA (5%), PRDM1 (10%), EP300 (10%) and NF1 (10%) were also enriched in the pPCL group compared to previously reported cases in non-pPCL MM. Biallelic inactivation of TP53 - a feature of Double Hit myeloma - was found in 6/19 (32%) samples, indicating a predominance of high risk genomic features compared to non-pPCL MM. Furthermore, analysis of mutational signatures in pPCL showed that aberrant APOBEC activity was highly prevalent only in patients with a MAF translocation, but not in other translocation groups. Conclusion: In conclusion we present one of the first WES datasets on pPCL with the largest patient cohort reported to date and show that pPCL is a highly complex disease. The aggressive disease behavior can, at least in part, be explained by a high prevalence of MAF and MYC translocations, TP53 and KRAS mutations as well as bi-allelic inactivation of TP53. It is of interest that only KRAS but not NRAS mutations are highly enriched in pPCL. From all highly prevalent genomic alterations in pPCL, only KRAS mutations offer a potential for already available therapeutically targeting with MEK inhibitors, which should be further explored. Disclosures Davies: Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees; ASH: Honoraria; TRM Oncology: Honoraria; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, Honoraria; Abbvie: Consultancy; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; MMRF: Honoraria. Barlogie:Multiple Myeloma Research Foundation: Other: travel stipend; ComtecMed- World Congress on Controversies in Hematology: Other: travel stipend; Millenium: Consultancy, Research Funding; European School of Haematology- International Conference on Multiple Myeloma: Other: travel stipend; International Workshop on Waldenström's Macroglobulinemia: Other: travel stipend; Celgene: Consultancy, Research Funding; Dana Farber Cancer Institute: Other: travel stipend; Myeloma Health, LLC: Patents & Royalties: : Co-inventor of patents and patent applications related to use of GEP in cancer medicine licensed to Myeloma Health, LLC. Morgan:Bristol-Myers Squibb: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Research Funding; Takeda: Consultancy, Honoraria; Janssen: Research Funding.

Characterization of Human Multiple Myeloma Cells with High-Resolution Magic Angle Spinning Magnetic Resonance Spectroscopy

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 5122-5122
Author(s):  
Albert Oriol ◽  
Ignasi Barba ◽  
Angels Barbera ◽  
Carles Arús ◽  
Jose-Luis Garcia-Dorado ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Bone Marrow ◽  
Magnetic Resonance ◽  
High Resolution ◽  
Plasma Cell ◽  
Plasma Cell Leukemia ◽  
Resonance Spectroscopy ◽  
Metabolic Profiles ◽  
Cell Leukemia ◽  
Myeloma Cells

Abstract Advancements in the pathogenetic pathways in multiple myeloma have led to the identification of several primary and secondary genetic lesions and ultimately to a multiple myeloma genetic classification with prognostic implications. Although disregulation of cyclin activity has been recognized as a key event leading to the multiple myeloma phenotype, little is known about the metabolic consequences of this phenomenon. We have studied intact multiple myeloma cells by high resolution magnetic resonance spectroscopy to establish the metabolomic profiles of different native multiple myeloma cells as compared to other lymphoproliferative disorders. Multiple myeloma cells obtained from bone marrow aspirates (n =15), blood (n =3) or other biologic tissues (n =2) from 20 multiple myeloma patients and separated by density gradient centrifugation were evaluated and metabolic profiles were correlated with cytogenetic characteristics of the disease and patients clinical characteristics. Twelve patients were females (60%) with a median age of 65 years (range 50–82). Multiple myeloma monoclonal proteins were IgG (N=9), IgA (N=5) or BJ (N=6). Five of them (25%) had renal insufficiency. Nine patients (45%) had predominantly extramedullar diesase including four cases of plasma cell leukemia. IgH translocations were identified in 5 samples (25%), hyperploidy in 2 (10%), and other or no genetic lesions in 13 (65%), del13 was present in 9 samples (45%) and p53 alterations in 5 (25%). Bone marrow samples from thirteen patients with conventional multiple myeloma presented a relatively constant metabolic pattern with predominantly lipidic signals and a metilen to metil ratio ranging from 1.9 to 4.9 (median 2.9). No differences in this pattern were observed among subgroups of primary translocations or involvement of Rb and p53 genes. Four patients with plasma cell leukemia and three with predominant extranodal disease presented either non detectable lipid signals (N=3) or a higher metilen to metil ratio ranging from 2.8 to 3.9 (median 3.5). In fact, extranodal or leukemic disease was significantly associated to undetectable lipids (P < 0.031) or the composite variable undetectable lipids or metilen to metil ratio > 3 (P < 0.043). Furthermore, after a median follow-up of 18 months, absence of lipids in the metabolic profile was also associated to a shorter survival (median 0.45 years, 95%CI 0–1.03 versus 3 years, 95%CI 0.95–5.06, P < 0.022). These results suggest that metabolic profiles of different multiple myeloma genetic subtypes share common and reletively constant characteristics, while cells obtained from patients with plasma cell leukemia or predominantly extramedullar disease present a clearly distinct profile, probably reflecting the metabolic effect of clonal evolution at a genetic level.

Pilot Study To Evaluate The Prevalence Of Actionable Oncogenic Mutations In Patients With Relapsed Refractory Multiple Myeloma

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 755-755 ◽  
Author(s):  
Alexander Lesokhin ◽  
Mithat Gonen ◽  
Kaitlyn Redling ◽  
Nikoletta Lendvai ◽  
Hani Hassoun ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Bone Marrow ◽  
Pilot Study ◽  
High Risk ◽  
Plasma Cell ◽  
Proteasome Inhibitor ◽  
Research Funding ◽  
Small Sample ◽  
Braf V600e ◽  
Oncogenic Mutations

Abstract Background Patients with multiple myeloma (MM) have realized improved survival with the development of multi-drug combinations using immunomodulatory drugs (IMiDs), proteasome inhibitors, and alkylating agents. Nevertheless, all MM patients eventually become refractory to available therapies, underscoring the importance of identifying additional rational therapeutic targets. Recent genomic studies using exome/copy number analysis have demonstrated that, at presentation, multiple myeloma is characterized by a dominant plasma cell clone and a heterogeneous group of subclones, with resistance emerging due to altered clonal dominance driven by therapeutic selective pressure or clonal evolution through the acquisition of additional mutational events. This suggests oncogenic mutations in dominant plasma cell clones in multiply relapsed disease may not only be involved in resistance, but should also be prioritized for further clinical development. Methods We performed a pilot study by sequencing DNA from cryopreserved whole bone marrow aspirate samples obtained pre-treatment from 28 patients with newly diagnosed myeloma (Cohort A) and 27 heavily pre-treated patients enrolled on a phase II clinical study of infusional carfilzomib (NCT01351623), a selective 2nd generation proteasome inhibitor (Cohort B). Genomic DNA and total RNA was isolated from all patient samples. Adaptor ligated sequencing libraries were captured by solution hybridization using two custom baitsets targeting 374 cancer-related genes and 24 genes frequently rearranged for DNA-seq, and 258 genes frequently rearranged for RNA-seq. All captured libraries were sequenced to high depth (Illumina HiSeq), averaging 712X for DNA and >20,000,000 total pairs for RNA, to enable the sensitive and specific detection of genomic alterations. Results Median follow-up for both cohorts was 21 months (26.3m for A; 15.6m for B). Cohort B patients were treated with a median of 5 prior therapies, with 74% refractory to the non-selective 1st generation proteasome inhibitor bortezomib, 70% refractory to IMiD therapy, and 55% refractory to both therapies. 44% had high-risk cytogenetics. Responses to initial therapy in Cohort A demonstrated that 21%, 7%, and 7%, respectively harbored bortezomib--resistant, IMiD-resistant, or double-resistant myeloma at presentation. 28% of cohort A patients had high risk cytogenetics. We obtained high coverage, high quality sequence data for 54/55 cases and examined alteration prevalence in the 35 samples with sufficient plasma cell content. We observed a high frequency of mutations in the MAPK pathway, including mutually exclusive mutations in NRAS and KRAS in 48% of cases and BRAF V600E mutation in 3%. 14% of cases had TET2 frameshift/nonsense mutations or IDH2 mutations, suggesting the DNA hydroxymethylation pathway is targeted by recurrent somatic mutations in MM. Given that MEK/RAF inhibition has demonstrated efficacy in a spectrum of human tumors and that there are emerging data that epigenetic (decitabine and 5-azacytadine) and targeted (IDH2) therapies offer significant benefit in patients with TET2/IDH mutations, these data demonstrate that mutational profiling can identify patients with actionable mutations that can lead to novel therapies, including mechanism-based clinical trials. Taken together, we identified mutations in epigenetic modifiers in 41% of the patients in our cohort, including mutations in TET2/IDH, in chromatin modifying enzymes/scaffolds (ARID1A, ASXL1), and DNA methyltransferases (DNMT3A). Moreover, we identified novel mutations in DNA repair pathways (ATM, FANCA, FANCD2) and in FAT3, suggesting there are novel disease alleles, which require functional investigation for their role in MM pathogenesis. No differences in mutation frequency were found between bortezomib sensitive vs resistant MM cases present in either cohort. We did not identify mutations, which impacted progression free and overall survival in this small sample set. Conclusions We demonstrate next generation sequencing of unsorted bone marrow samples is feasible in MM and can rapidly identify actionable mutations based on genetic profiling of limited clinical isolates. These include the identification of mutations, which can guide therapeutic trials of clinically targeting specific oncogenic pathways (ex, MAPK or TET2/IDH) on an individual patient level. Disclosures: Lesokhin: Janssen Pharmaceuticals, Inc: Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Foundation Medicine, inc: Consultancy. Brennan:Foundation Medicine, Inc: Employment. Wang:Foundation Medicine, Inc: Employment. Sanford:Foundation Medicine, Inc: Employment. Brennan:Foundation Medicine, Inc: Employment. Otto:Foundation Medicine, Inc: Employment. Nahas:Foundation Medicine, Inc: Employment. Lipson:Foundation Medicine, Inc: Employment. Stephens:Foundation Medicine, Inc: Employment. Yelensky:Foundation Medicine, Inc: Employment. Miller:Foundation Medicine, Inc: Employment. Levine:Foundation Medicine, Inc: Consultancy. Dogan:Foundation Medicine, Inc: Consultancy.

scholarly journals Molecular Characterization of Bone Marrow and Peripheral Blood Compartments from Patients with Plasma Cell Leukemia in the Mmrf Commpass Study

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 1782-1782
Author(s):  
Sheri Skerget ◽  
Austin Christofferson ◽  
Sara Nasser ◽  
Christophe Legendre ◽  
The MMRF CoMMpass Network ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Multiple Myeloma ◽  
Bone Marrow ◽  
Flow Cytometry ◽  
Plasma Cell ◽  
Peripheral Blood ◽  
Research Funding ◽  
Plasma Cells ◽  
Cell Cycle Control ◽  
Cell Leukemia

Plasma cell leukemia (PCL) is rare but represents an aggressive, advanced form of multiple myeloma (MM) where neoplastic plasma cells (PCs) escape the bone marrow (BM) and circulate in the peripheral blood (PB). Traditionally, PCL is defined by the presence of >20% circulating plasma cells (CPCs), however, recent studies have suggested that PCL be redefined as the presence of >5% CPCs. The Multiple Myeloma Research Foundation CoMMpass study (NCT01454297) is a longitudinal, observational clinical study with 1143 newly diagnosed MM patients. BM-derived MM samples were characterized using whole genome (WGS), exome (WES), and RNA (RNAseq) sequencing at diagnosis and each progression event. When >5% CPCs were detected by flow cytometry, PCs were enriched independently from both compartments, and T-cells were selected from the PB as a control for WGS and WES. This substudy within CoMMpass provides the largest, most comprehensively characterized dataset of matched MM and PCL samples to date, which can be leveraged to better understand the molecular drivers of PCL. At diagnosis, 813/1143 CoMMpass patients had flow cytometry data reporting the percent PCs in PB, of which 790 had <5%, 17 had 5-20%, and 6 had >20% CPCs. Survival analyses revealed that patients with 5-20% CPCs (median = 20 months) had poor overall survival (OS) outcomes compared to patients with <5% CPCs (median = 74 months, p < 0.001), and no significant difference in outcome was observed between patients with 5-20% and >20% (median = 38 months) CPCs. Patients with 1-5% CPCs (median = 50 months, HR = 2.45, 95% CI = 1.64 - 3.69, p < 0.001) also exhibited poor OS outcomes compared to patients with <1% CPCs (median = 74 months), suggesting that patients with >1% CPCs are a higher risk population, even if they do not meet the PCL threshold. Using a cutoff of >5% CPCs, 23/813 (2.8%) patients presented with primary PCL (pPCL) at diagnosis. Of these patients, 7 (30%) were hyperdiploid (HRD), of whom 1 had a CCND1 and 1 had a MYC translocation; while 16 (70%) were nonhyperdiploid (NHRD), all of whom had a canonical immunoglobulin translocation (6 CCND1, 5 WHSC1, 3 MAF, 1 MAFA, and 1 MAFB). Of 124 patients with serial sample collections, 5 (4%) patients without pPCL had >5% CPCs at progression, and thus relapsed with secondary PCL (sPCL). Of the 5 sPCL patients, 2 (40%) were NHRD with a CCND1 or MAF translocation; while 3 (60%) were HRD, 1 with a WHSC1 translocation. Median time to diagnosis of sPCL was 22 months (range = 2 - 31 months), and patients with sPCL (median = 22 months) and pPCL (median = 30 months) exhibited poor OS outcomes as compared to MM patients (74 months, p < 0.001). Sequencing data was available for 15 pPCL and 5 sPCL samples. For 12 patients with WES, WGS, and RNAseq performed on their PCL tumor sample, an integrated analysis identified recurrent, complete loss-of-function (LOF) events in only CDKN2C/FAF1, SETD2, and TRAF3. Five pPCL patients had complete LOF of a gene involved in G1/S cell cycle control, including CDKN2C, CDKN2A, CDKN1C, and ATM. These LOF events were not observed in NHRD t(11;14) PCL patients, suggesting that CCND1 overexpression and LOF of genes involved in G1/S cell cycle control may represent independent drivers of PCL. Comparing WES and WGS data between matched MM and PCL tumor samples revealed a high degree of similarity in mutation and copy number profile. However, differential expression analysis performed for 13 patients with RNAseq data comparing their MM and PCL tumors revealed 27 up- and 39 downregulated genes (padj < 0.01, FDR = 0.1) in PCL versus MM. Pathway analysis revealed an enrichment (p < 0.001) for genes involved in adhesion and diapedesis, including upregulation of ITGB2, PF4, and PPBP, and downregulation of CCL8, CXCL12, MMP19, and VCAM1. The most significantly downregulated gene in PCL (log2FC = -6.98) was VCAM1, which plays a role in cell adhesion, and where loss of expression (TPM < 0.01) was observed across all PCL samples. Upregulation of four S100 genes including S100A8, S100A9, S100A12, and S100P, which have been implicated in tumor growth, metastasis, and immune evasion, was also observed in PCL. Interestingly, a S100A9 inhibitor has been developed and may represent a novel treatment option for PCL patients. In summary, PCL was found to be associated with molecular events dysregulating G1/S cell cycle control coupled with subtle changes in transcription that likely occur in a subclonal population of the MM tumor. Disclosures Lonial: Genentech: Consultancy; GSK: Consultancy; BMS: Consultancy; Janssen: Consultancy, Research Funding; Karyopharm: Consultancy; Takeda: Consultancy, Research Funding; Celgene Corporation: Consultancy, Research Funding; Amgen: Consultancy.

Phase 2 Trial of Pomalidomide, Ixazomib and Dexamethasone in Patients with Multiple Myeloma with Extramedullary Disease or Plasma Cell Leukemia

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 34-35
Author(s):  
Francis K. Buadi ◽  
Martha Q. Lacy ◽  
Gabriela Perez ◽  
Liang Phuong-Dung ◽  
Ankit Kansagra ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Clinical Trials ◽  
Plasma Cell ◽  
Research Funding ◽  
Plasma Cells ◽  
Response Rate ◽  
Advisory Board ◽  
Plasma Cell Leukemia ◽  
Cell Leukemia ◽  
Grade 3

Background: Multiple myeloma is typically characterized by clonal expansion of malignant plasma cells within the bone marrow compartment. Presence of extramedullary disease (EMD) either in the form of soft tissue plasmacytoma or circulating plasma cells can be seen at diagnosis but is more common in the relapsed and refractory patients. Presence of EMD is typically associated with a poor prognosis, both in the newly diagnosed and relapsed setting, but trials designed specifically for patients with EMD are sparse. Treatment of EMD can be challenging and the responses even when seen are often short lasting, highlighting the need for developing specific treatment approaches aimed at these patients. Based on initial trials suggesting activity of pomalidomide in the setting of EMD and the increased tissue distribution with the oral proteasome inhibitor ixazomib, we designed this trial to examine if the all oral combination of ixazomib, pomalidomide and dexamethasone can be effective in the setting of EMD. Patients and Methods: Patients with previously treated multiple myeloma, with adequate hematologic and organ function were enrolled if there was evidence, at study entry, of EMD defined as one or more plasmacytomas, outside the bone marrow that were non-contiguous with a bone lesion and had a single diameter of ≥2 cm OR as plasma cell leukemia, with circulating plasma cells &gt; 5% of peripheral blood leukocytes or at least 0.5 X 109/L or 200 cells/150000 events by flowcytometry. Patients were treated on 28-day cycles, with ixazomib 4 mg on days 1, 8, and 15 along with pomalidomide 4 mg PO daily on days 1-21 and dexamethasone 40 milligrams weekly until disease progression or unacceptable toxicity. The goals of the study were to determine confirmed response rate (≥ PR), toxicities of this combination, differential response rates and progression-free survival (PFS). Confirmed response rate, differential response rates and PFS were estimated using Duffy and Santner approach, exact binomial distributions and Kaplan Meier curves, respectively. The study was designed to accrue 30 patients. Results: This study was designed to enroll up to 30 patients but was closed after enrolling 17 patients due to slow accrual. The baseline characteristics are as indicated in Table 1. Eleven patients were enrolled with an extramedullary plasmacytoma while the remaining six patients had plasma cell leukemia. Median number of lines of prior therapy was 3 (range: 1, 7). Overall, 10 (58.8%) patients had progressive disease and 11 (64.7%) patients have died, median (range) follow-up for the live patients is 22.2 (2.1, 37.9) months. Patients were treated for a median of 2 (range 1-34) cycles. A grade 3+ AE, at least possibly attributed, was seen in 53%. Grade 3+, at least possibly related, hematologic toxicity was noted in 41%, with 29% experiencing grade 3+ neutropenia. Notable grade 3+ non-hematologic toxicities (regardless of attribution), with &gt;10% incidence rate were anemia, hypoxia, infections and lung infection. The confirmed response rate in evaluable patients was 35% (1 CRs and 5 PRs), with a 90% CI of 6% - 37%. While 33% (4/12; 95% CI: 1-8%) of patients reported a biochemical response, 40% (2/5; 95% CI: 0-4%) of patients reported an extramedullary response. The median PFS was 4.5 (95% CI: 2-11.8) months. Conclusions: The combination of ixazomib, pomalidomide and dexamethasone resulted in disease response in a third of this group of high-risk patients with EMD; however, the responses were not very durable, with a median PFS of only 4.5 months. The trial highlights the feasibility of doing clinical trials specifically targeted towards this high-risk patient population. Future trials should explore combinations of novel agents, including monoclonal antibodies through multicenter collaborative efforts. Disclosures Kansagra: Alnylam Pharmaceuticals, Bristol Myers Squibb /Celgene, GlaxoSmithKline, Janssen, Pharmacyclics, Takeda Pharmaceuticals, Pfizer, Karyopharm Therpeutics: Other: Advisory Board. Witzig:Spectrum: Consultancy; Immune Design: Research Funding; Karyopharm Therapeutics: Research Funding; Acerta: Research Funding; Incyte: Consultancy; AbbVie: Consultancy; MorphSys: Consultancy; Celgene: Consultancy, Research Funding. Kumar:Oncopeptides: Consultancy, Other: Independent Review Committee; IRC member; Genecentrix: Consultancy; Carsgen: Other, Research Funding; Cellectar: Other; Celgene/BMS: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Dr. Reddy's Laboratories: Honoraria; AbbVie: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Takeda: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Janssen Oncology: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; Merck: Consultancy, Research Funding; Amgen: Consultancy, Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments, Research Funding; Kite Pharma: Consultancy, Research Funding; Novartis: Research Funding; Adaptive Biotechnologies: Consultancy; Genentech/Roche: Other: Research funding for clinical trials to the institution, Consulting/Advisory Board participation with no personal payments; BMS: Consultancy, Research Funding; Karyopharm: Consultancy; MedImmune: Research Funding; Sanofi: Research Funding; Tenebio: Other, Research Funding.

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