High Expression of the Thalidomide-Binding Protein Cereblon (CRBN) Is Associated with Improved Clinical Response in Patients with Multiple Myeloma Treated with Lenalidomide and Dexamethasone

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 2879-2879 ◽  
Author(s):  
Daniel Heintel ◽  
Arnold Bolomsky ◽  
Martin Schreder ◽  
Sabine Pfeifer ◽  
Niklas Zojer ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Bone Marrow ◽  
Board Of Directors ◽  
Cell Lines ◽  
Research Funding ◽  
Univariate Analysis ◽  
Myeloma Cell ◽  
Full Data ◽  
Advisory Committees ◽  
Starting Dose

Abstract Abstract 2879 Background: Immunomodulatory drugs (IMiDs) are highly active in the treatment of multiple myeloma (MM), but the mechanisms of action are still not completely understood. Recently, cereblon (CRBN) has been identified as the primary target of thalidomide teratogenicity (Ito K et al, 2010) and, moreover as an essential requirement for IMiD therapy (Zhu YX et al, 2011). We wanted to investigate, if expression levels of CRBN could serve as a predictor of response. Patients and Methods: We measured CRBN mRNA expression in bone marrow samples of 44 well characterized MM patients treated with lenalidomide containing regimens, myeloma cell lines, and normal bone marrow (BM), using real time PCR. The median age of patients was 65 years (range: 37–85 years). Nine patients had ISS-stage I, 9 stage II, and 26 had stage III. All patients, except 12, were newly diagnosed. None of the patients had been exposed to lenalidomide before study entry. Full data documentation for response evaluation (> 2 cycles) was available in 37 patients (84%). Of these, lenalidomide was given in combination with dexamethasone in 27 patients with a starting dose of 25 mg per day on days 1–21 in a 28 days cycle, in combination with melphalan and prednisone (MPR, starting dose of lenalidomide 10 mg per day on days 1–21) in 9 patients, and in combination with bendamustine in 1 patient. Results: Normal BM was used as a reference with an expression level of one. All multiple myeloma cell lines tested (U266, KMS-12-BM, OPM-2, NCL-H929, MM.1S, SK-MM-1, and RPMI8226), had a higher CRBN expression than normal BM. CRBN was detected in all 44 MM samples distributed over a range covering 3 orders of magnitude (0.31 to 462.08-fold relative to normal BM; median: 3.61). Lenalidomide-based therapy resulted in CR in 3 (8%), nCR in 2 (5%), VGPR in 4 (11%), PR in 17 (46%), and in MR in 4 patients (11%), respectively. Three patients (8%) had SD, and 4 (11%) had PD. Median CRBN expression was three times higher in responding (≥MR) patients compared to non-responders (3.65 vs. 0.99, p<0.01). In addition, a significant correlation between quality of response and CRBN expression (r=0.34) was observed. This correlation remained statistically significant after exclusion of previously treated patients (r=0.37, p=0.02). Interestingly, among 9 available patients who had been pretreated, the lowest level of CRBN expression (0.90) was noted in the patient who progressed during lenalidomide treatment, indicating a predictive potential of CRBN expression also in pre-treated patients. When the analysis was restricted to the 27 patients who had uniformly been treated with lenalidomide and dexamethasone, an even more pronounced association between myeloma response and CRBN expression was noted (r=0.45; p=0.008). In patients with SD or PD, median CRBN expression was lower than in normal BM, while a higher CRBN expression was found in all patients with CR, nCR, VGPR, PR or MR (Table 1), suggesting that CRBN was required for anti-myeloma activity in these patients. This applied also to patients with marked myeloma response (CR, nCR, VGPR) and patients with PD (r=0.82; p= 0.003) (Figure 1). Univariate analysis between established prognostic factors such as beta-2-microglobulin, albumin, ISS stage, Hb, FISH defined cytogenetic aberrations, and response revealed no significant correlation in this patient cohort. A highly significant correlation between expression of CRBN and IRF4, an important transcription factor required for myeloma survival (p=0.00007), and XBP1 (p=0.00004) was observed. For PAX5 and BLIMP no such association were noted. When primary myeloma cells of 5 patients and cell lines (U 266, KMS-12-M) were exposed to lenalidomide, a significant down regulation of IRF4, but not of CRBN was found. Conclusion: Our studies show a significant association between CRBN expression and myeloma response in patients treated with lenalidomide containing regimens, especially in those receiving lenalidomide and dexamethasone therapy. These findings should be confirmed in larger, prospective clinical trials. Disclosures: Jäger: Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Mundipharma: Honoraria, Membership on an entity's Board of Directors or advisory committees; AMGEN: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Research Funding; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Biogen: Research Funding.

Expression Of Truncated Protein Tyrosine Phosphatase, Receptor Type, O (PTPROt) Influences Multiple Myeloma Sensitivity To Bortezomib Through Akt Signaling, and Is a Favorable Clinical Prognostic Factor

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 2520-2520
Author(s):  
Hua Wang ◽  
Veerabhadran Baladandayuthapani ◽  
Zhiqiang Wang ◽  
Jiexin Zhang ◽  
Heather Yan Lin ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Board Of Directors ◽  
Cell Lines ◽  
Research Funding ◽  
Myeloma Cell ◽  
Advisory Committees ◽  
Over Expression ◽  
Resistant Disease ◽  
Drug Naïve ◽  
Rpmi 8226

Abstract Background Proteasome inhibitors such as bortezomib and carfilzomib are an important part of our current chemotherapeutic armamentarium against multiple myeloma, and have improved outcomes in the up-front, relapsed, and relapsed/refractory settings. Their efficacy has been demonstrated both as single agents, and as part of rationally designed combination regimens, but they are at this time used empirically, since biomarkers to identify patients who would most or least benefit from their application have not been clinically validated. Moreover, the vast majority of patients eventually develop drug-resistant disease which precludes further proteasome inhibitor use through mechanisms that have not been fully elucidated. Methods We compared gene expression profiles (GEPs) of a panel of bortezomib-resistant myeloma cell lines and their vehicle-treated, drug-naïve counterparts to identify significant changes associated with drug resistance. The list of genes whose expression was changed by at least 2-fold was compared with independent RNA interference studies whose goal was to identify genes whose suppression conferred drug resistance. Further validation of genes of interest was pursued in a panel of myeloma cell lines, and in clinically annotated GEP databases. Results Suppression of PTPROt expression was noted in bortezomib-resistant RPMI 8226 and ANBL-6 myeloma cells compared to isogenic, drug-naïve controls, and this was confirmed by quantitative PCR. Overexpression of PTRPOt in RPMI 8226, ANBL-6 and other myeloma cell lines was by itself sufficient to increase the level of apoptotic, sub-G0/G1 cells compared to vector controls, or cells expressing a phosphatase-dead PTPROt mutant. Moreover, PTPROt enhanced the ability of bortezomib to reduce myeloma cell viability, in association with increased activation of caspases 8 and 9. Exogenous over-expression of PTPROt was found to reduce the activation status of Akt, a known anti-apoptotic pathway that reduces bortezomib activity, based on Western blotting with antibodies to phospho-Akt (Ser473), and Akt kinase activity assays. Notably, we also found that exogenous over-expression of PTPROt resulted in increased expression levels of p27Kip1. Interestingly, array CGH data from studies of myeloma cell lines and primary cells showed that the PTPROt gene was located in a genomic region with a high propensity for loss. Analysis of the Total Therapy databases of GEP and patient outcomes available on the Multiple Myeloma Genomics Portal showed that higher than median expression of PTPROt was associated with better long-term survival (P=0.0175). Finally, analysis of the Millennium Pharmaceuticals database of studies of bortezomib in the relapsed and relapsed/refractory setting showed high PTRPOt expression was more frequently seen in patients who achieved complete remission (P<0.01), and was associated with a better median overall survival (P=0.0003). Conclusions Taken together, the data support the possibility that high expression of PTPROt is a good prognostic factor for response to bortezomib-containing therapies, and that this may occur through modulation by PTPROt of the Akt pathway. Moreover, they suggest that strategies to enhance the expression of PTPROt should be investigated to restore bortezomib sensitivity in patients with proteasome inhibitor-resistant disease. Disclosures: Orlowski: Bristol-Myers Squibb: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Celgene: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Millennium: The Takeda Oncology Company: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Onyx: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Resverlogix: Research Funding; Array Biopharma: Honoraria, Membership on an entity’s Board of Directors or advisory committees; Genentech: Honoraria, Membership on an entity’s Board of Directors or advisory committees; Merck: Membership on an entity’s Board of Directors or advisory committees.

Proteolytic Targeting Chimeric Molecules (PROTACs) Specific for Bromodomain-Containing Protein (BRD) 4 Are Active Against Pre-Clinical Models of Multiple Myeloma

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 917-917 ◽  
Author(s):  
Xiaohui Zhang ◽  
Jing Lu ◽  
Yimin Qian ◽  
Robert Z. Orlowski
Keyword(s):  
Multiple Myeloma ◽  
Board Of Directors ◽  
Cell Lines ◽  
Research Funding ◽  
Myeloma Cell ◽  
Employment Equity ◽  
Advisory Committees ◽  
Clinical Models ◽  
Equity Ownership ◽  
Rpmi 8226

Abstract Background: BRD4, a bromodomain and extraterminal domain (BET) family member, has an important role in modulating the expression of essential oncogenes such as c-MYC, and is emerged as a promising therapeutic target in diverse cancer types. Pharmacologic BET inhibitors in development such as JQ1 and OTX015 display preclinical anti-myeloma activity, and induce preferential loss of BRD4 bound to super-enhancers leading to transcriptional repression of c-MYC. Another approach to target this pathway is through the use of bi-functional molecules, which incorporate a small molecule BRD4 binding moiety with an E3 ubiquitin ligase recognition motif, such as ARV-825 and dBET1 (Lu et al. Chem Biol. 22:755, 2015, Winter et al. Science 348:1376, 2015). These agents induce Cereblon (CRBN)-dependent BRD4 ubiquitination and then proteasome-mediated degradation, thereby also reducing downstream c-MYC protein levels. Methods: We performed pre-clinical studies in myeloma cell lines and primary samples using ARV-825 and ARV-763, which are PROTACs that target BRD4 to either the CRBN or the Von Hippel-Lindau (VHL) E3 ligases, respectively. Downstream effects were studied using viability and apoptosis assays, cell cycle profiling, and Western blotting, among others. Results: Tetrazolium assays showed that both PROTACs were able to reduce the viability of a panel of myeloma cell lines, including MM1.S, U266, RPMI 8226, ANBL-6, KAS-6/1, and OPM-2 cells, and this occurred with greater potency than was the case for the BRD4 inhibitors JQ1 or OTX015. Median inhibitory concentrations were 5.66-91.98 nM for ARV-825, and 13.22-1522 nM for ARV-763, respectively. This reduction in viability was both time- and concentration-dependent, and was associated with a reduction of cells in the S phase, and an increase in G0/G1 cells, as well as cells with sub-G0/G1 DNA content, suggesting the onset of apoptosis. Programmed cell death was indeed found to be induced based on the appearance of an increase in Annexin V-positive cells by flow cytometry, and in cleaved caspase 8, caspase 9, caspase 3, and poly-ADP-ribose polymerase by Western blotting. The latter was associated with a specific reduction in the expression levels of both BRD4 and c-MYC that did not influence the abundance of other cellular proteins that were not BRD4 targets, and in a reduction in BRD4 and c-MYC mRNA. In contrast, JQ1 and OTX015 exposure resulted in a slight increase in BRD4 protein expression and a lesser decrease of c-MYC protein. Studies of drug combinations showed that, as expected, lenalidomide and pomalidomide were antagonistic to the effects of the CRBN-targeted ARV-825 PROTAC, but these immunomodulatory drugs showed additive or synergistic effects in combination with the VHL-targeted agent ARV-763. Also as expected, bortezomib and carfilzomib reduced the ability of both ARV-825 and ARV-763 to induce BRD4 degradation, but enhanced anti-proliferative and pro-apoptotic effects were seen in a manner that was influenced by the sequence of drug addition. In studies of drug-resistant cell lines, both PROTACs were able to overcome dexamethasone, melphalan, lenalidomide, and bortezomib resistance, but cross-resistance was seen in RPMI 8226/Dox40 cells, suggesting that these compounds are substrates for P-glycoprotein, which is over-expressed in these cells. Finally, we tested BRD4 PROTACs in primary cells isolated from patients with multiple myeloma, and observed rapid loss of viability of these plasma cells. Conclusions: Taken together, our data demonstrate that BRD4 degraders have promising activity against pre-clinical models of multiple myeloma, and support their translation to the clinic for patients with relapsed/refractory disease. Additional combination and mechanistic studies, as well as data from ongoing in vivo studies, will be presented at the meeting. Disclosures Lu: Arvinas, LLC: Employment, Equity Ownership. Qian:Arvinas, LLC: Employment, Equity Ownership. Orlowski:Acetylon: Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Consultancy, Research Funding; Forma Therapeutics: Consultancy; Celgene: Consultancy, Research Funding; Millennium Pharmaceuticals: Consultancy, Research Funding; Array BioPharma: Consultancy, Research Funding; Onyx Pharmaceuticals: Consultancy, Research Funding; Janssen Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Genentech: Consultancy; BioTheryX, Inc.: Membership on an entity's Board of Directors or advisory committees; Spectrum Pharmaceuticals: Research Funding.

Identification Of Tight Junction Protein (TJP)-1 As a Modulator and Biomarker Of Proteasome Inhibitor Sensitivity In Multiple Myeloma

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 123-123 ◽  
Author(s):  
Xing-Ding Zhang ◽  
Veerabhadran Baladandayuthapani ◽  
Heather Yan Lin ◽  
Bart Barlogie ◽  
Saad Z Usmani ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Drug Resistance ◽  
Rna Interference ◽  
Board Of Directors ◽  
Cell Lines ◽  
Research Funding ◽  
Myeloma Cell ◽  
Advisory Committees ◽  
Junction Protein ◽  
Rpmi 8226

Abstract Background Inhibition of the ubiquitin-proteasome pathway through the use of proteasome inhibitors (PIs) has been validated by our group and others as a successful strategy against multiple myeloma that has improved patient outcomes. However, these agents are currently used without patient selection, as no biomarkers have been validated that identify patients most or least likely to benefit. Also, drug resistance emerges in the vast majority through largely undefined mechanisms, and limits the activity of further therapy based on PIs. There is therefore an urgent need to identify such biomarkers, especially if they could also represent novel therapeutic targets to achieve resensitization. Methods We compared gene expression profiles (GEPs) of a panel of bortezomib-resistant myeloma cell lines and their vehicle-treated, drug-naïve counterparts to identify significant changes associated with drug resistance. In addition, using the Lentiviral GeneNet™ small hairpin (sh) RNA Library, we performed genome-wide RNA interference (RNAi) to identify genes whose knockdown conferred resistance. Genes of interest were subjected to further validation using myeloma cell lines,primary samples, murine models, and using clinically annotated GEP databases. These studies were supported by the M. D. Anderson Cancer Center SPORE in Multiple Myeloma. Results Bortezomib resistance was associated with decreased expression of TJP1 by GEP studies of isogenic bortezomib-resistant and -sensitive cell lines. TJP1 was also identified as a chemoresistance factor by RNA interference designed to detect genes that conferred a survival advantage after drug treatment. Suppression of TJP1 using shRNAs in RPMI 8226 and U266 myeloma cell lines with high TJP1 expression reduced sensitivity to both bortezomib and carfilzomib. Conversely, its over-expression in MOLP-8 cells, which had low TJP1 levels, conferred enhanced sensitivity to both PIs. Also, forced expression of TJP1 in bortezomib-resistant RPMI 8226 cells that had lost endogenous TJP1 levels restored drug sensitivity. In these resistant cells, TJP1 promoter hypermethylation was found, and treatment with decitabine restored both TJP1 expression, and sensitivity to bortezomib or carfilzomib. GEP studies showed TJP1 suppression was associated with enhanced expression of MHC class II region genes, including PSMB8 and PSMB9. This was mirrored at the protein level by enhanced PSMB8 and PSMB9 protein by Western blotting. As a result, TJP1 suppression was associated with increased activity of the chymotrypsin-like activity of the proteasome, while TJP1 overexpression reduced proteasome activity. A link between TJP1 and PSMB8 and 9 was supported by studies showing that TJP1 influenced activity of EGFR and STAT3 and indeed, EGFR inhibition with erlotinib enhanced PI sensitivity. Consistent with a role for TJP1 in vivo, treatment of mice with bortezomib showed a greater reduction of myeloma growth in tumors with high TJP1 expression compared with isogenic lines with low TJP1 expression. Finally, analysis of the Millennium Pharmaceuticals database of bortezomib studies in the relapsed and relapsed/refractory settings showed high TJP1 expression was associated with a greater likelihood of responding to bortezomib (p<0.0002), and a longer median overall survival (OS)(p=0.008). In addition, in the Total Therapy (TT) databases, higher TJP1 expression was associated with a better progression-free and OS in both TT3a (p=0.004 and <0.0001, respectively), and TT3b (p=0.001 and <0.0001). Conclusions Taken together, these data support the hypothesis that TJP1 modulates PI sensitivity in myeloma through effects on the proteasome’s protein turnover capacity, thereby tilting the load versus capacity balance in favor of cell death. Also, they indicate that strategies targeting TJP1 signaling should be studied as approaches to overcome both primary and secondary resistance. Finally, they support the possibility that TJP1 could be a useful biomarker to identify patients who are most likely to benefit from PI-based therapies, and prospective studies to validate this further are currently underway. Disclosures: Usmani: Celgene: Consultancy, Research Funding, Speakers Bureau; Onyx: Research Funding, Speakers Bureau. Orlowski:Genentech: Honoraria, Membership on an entity’s Board of Directors or advisory committees; Array Biopharma: Honoraria, Membership on an entity’s Board of Directors or advisory committees; Resverlogix: Research Funding; Onyx: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Millennium: The Takeda Oncology Company: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Celgene: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Bristol-Myers Squibb: Honoraria, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Merck: Membership on an entity’s Board of Directors or advisory committees.

scholarly journals The Lysine-Specific Demethylase KDM4A/JMJD2A Acts As a Tumor Suppressor in Multiple Myeloma

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 191-191
Author(s):  
Fengyan Jin ◽  
Shaji K. Kumar ◽  
Yun Dai
Keyword(s):  
Cell Cycle ◽  
Multiple Myeloma ◽  
Bone Marrow ◽  
Drug Resistance ◽  
Tumor Suppressor ◽  
Board Of Directors ◽  
Cell Lines ◽  
Research Funding ◽  
Advisory Committees ◽  
Apoptotic Genes

Abstract Introduction: Histone lysine methylation, a reversible event dynamically and reciprocally regulated by lysine methyltransferases (KMTs) and demethylases (KDMs), represents one of the major epigenetic mechanisms for regulation of chromatin remodeling and gene expression re-programming. The KDM4 family, which belongs to the Jumonji C (JmjC)-domain-containing proteins (JMJDs), consists of five members, including KDM4A-E that demethylate H3K9me2/3 and/or H3K36me2/3 in a Fe2+- and α-ketoglutarate-dependent manner. KDM4 proteins are involved in various cellular processes such as gene transcription and translation, DNA replication, DNA repair, apoptosis, and stem cell renewal. Notably, increasing evidence implicates KDM4 dysregulation in promoting genomic instabilities and oncogenesis, thereby which is considered as a potential target for emerging cancer epigenetic therapy. Although KDM4A, a member of the KDM4 family, has been widely studied in many solid tumors including breast, prostate, bladder cancer, its role in hematopoietic malignancies, including multiple myeloma (MM), remains unknown. Materials and Methods: Human MM cell lines (U266, RPMI8226, H929, OPM-2) were employed. After exposed to hypoxia (or the chemical hypoxia mimetic lactic acid) and anti-MM agents (e.g., bortezomib/Btz), cells were analyzed by flow cytometry, qPCR, Western blot to monitor apoptosis, cell cycle, proliferation (Ki67), DNA double-strand break/DSB (γH2A.X), expression of 1q21 and anti-apoptotic genes, as well as activation of the NF-κB and HIF pathways. The shRNA approach was used to knock down KDM4A for functional evaluation. The findings from in vitro experiments involving cell lines were then validated in primary MM samples to link KDM4A expression to disease progression and therapeutic response. Results: Analysis of the MM genome-wide GEP databases revealed that KDM4A mRNA was significantly up-regulated in MGUS and MM, but not SMM, compared to normal control, as well as in relapsed MM, compared to newly-diagnosed MM. To our surprise, KDM4A expression rather favored overall survival of MM patients, including those carrying 1q21 gain in whom KDM4A expression was indeed lower than those who did not have this high risk cytogenetic abnormality. Moreover, KDM4A expression correlated adversely with expression of 1q21 genes (e.g., CKS1B, MCL1, PSMD4, ARNT). Whereas basal KDM4A protein level was moderately but clearly higher in MM cell lines carrying 1q21 gain or acquired drug resistance than their counterparts, exposure to hypoxia or lactic acid (but not cobalt chloride) resulted in marked KDM4A up-regulation, accompanied by NF-κB and HIF pathway activation. However, while NF-κB inhibition and to a lesser extent ARNT/HIF-1β knockdown led to a robust increase in hypoxia-induced KDM4A expression, shRNA knockdown or pharmacological inhibition of KDM4A triggered NF-κB activation and HIF expression, as well as up-regulated anti-apoptotic proteins (e.g., Mcl-1, TNFAIP3/A20, CKS1B), in association with increased H3K36me3 rather than H3K9me3. Furthermore, KDM4A knockdown or inhibition sharply diminished Btz lethality and overrode hypoxia-mediated cytoprotection. Interestingly, KDM4A knockdown also increased MM cell proliferation, promoted S phase entry, and attenuated Btz-induced DSB. Last, IHC of sequential bone marrow biopsies revealed that while KDM4A protein was relatively low at diagnosis, its level was markedly increased when patients achieved CR and then fell to the baseline low level at relapse. Conclusion: KDM4A/JMJD2A, a lysine demethylase that has been recognized as an pro-oncogenic protein via its epigenetic and/or non-epigenetic properties, is identified for the first time as a potential tumor suppressor in MM, particularly in a high risk subtype carrying 1q21 gain. Whereas KDM4A is expressed in MM and can be further induced by hypoxia that naturally exists in bone marrow niche, it seems to play multiple inhibitory roles in cell growth, cell cycle, DNA repair, and drug resistance by suppressing expression of oncogenic and anti-apoptotic genes (especially 1q21 genes), likely via H3K36me3 demethylation, and antagonizing NF-κB and HIF activation. These findings suggest that in contrast to its pro-oncogenic role in certain solid tumors, KDM4A might instead act as a tumor suppressor in MM. This work was supported by NNSFC (81471165, 81670189, and 81670190). Disclosures Kumar: AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding; KITE: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding.

scholarly journals Phase II Trial of the Combination of Ixazomib, Lenalidomide, and Dexamethasone in High-Risk Smoldering Multiple Myeloma

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 804-804 ◽  
Author(s):  
Mark Bustoros ◽  
Chia-jen Liu ◽  
Kaitlen Reyes ◽  
Kalvis Hornburg ◽  
Kathleen Guimond ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Bone Marrow ◽  
High Risk ◽  
Disease Progression ◽  
Board Of Directors ◽  
Rna Sequencing ◽  
Research Funding ◽  
Response Rate ◽  
Advisory Committees ◽  
Equity Ownership

Abstract Background. This study aimed to determine the progression-free survival and response rate using early therapeutic intervention in patients with high-risk smoldering multiple myeloma (SMM) using the combination of ixazomib, lenalidomide, and dexamethasone. Methods. Patients enrolled on study met eligibility for high-risk SMM based on the newly defined criteria proposed by Rajkumar et al., Blood 2014. The treatment plan was designed to be administered on an outpatient basis where patients receive 9 cycles of induction therapy of ixazomib (4mg) at days 1, 8, and 15, in combination with lenalidomide (25mg) at days 1-21 and Dexamethasone at days 1, 8, 15, and 22. This induction phase is followed by ixazomib (4mg) and lenalidomide (15mg) maintenance for another 15 cycles. A treatment cycle is defined as 28 consecutive days, and therapy is administered for a total of 24 cycles total. Bone marrow samples from all patients were obtained before starting therapy for baseline assessment, whole exome sequencing (WES), and RNA sequencing of plasma and bone marrow microenvironment cells. Moreover, blood samples were obtained at screening and before each cycle to isolate cell-free DNA (cfDNA) and circulating tumor cells (CTCs). Stem cell collection is planned for all eligible patients. Results. In total, 26 of the planned 56 patients were enrolled in this study from February 2017 to April 2018. The median age of the patients enrolled was 63 years (range, 41 to 73) with 12 males (46.2%). Interphase fluorescence in situ hybridization (iFISH) was successful in 18 patients. High-risk cytogenetics (defined as the presence of t(4;14), 17p deletion, and 1q gain) were found in 11 patients (61.1%). The median number of cycles completed was 8 cycles (3-15). The most common toxicities were fatigue (69.6%), followed by rash (56.5%), and neutropenia (56.5%). The most common grade 3 adverse events were hypophosphatemia (13%), leukopenia (13%), and neutropenia (8.7%). One patient had grade 4 neutropenia during treatment. Additionally, grade 4 hyperglycemia occurred in another patient. As of this abstract date, the overall response rate (partial response or better) in participants who had at least 3 cycles of treatment was 89% (23/26), with 5 Complete Responses (CR, 19.2%), 9 very good partial responses (VGPR, 34.6%), 9 partial responses (34.6%), and 3 Minimal Responses (MR, 11.5%). None of the patients have shown progression to overt MM to date. Correlative studies including WES of plasma cells and single-cell RNA sequencing of the bone microenvironment cells are ongoing to identify the genomic and transcriptomic predictors for the differential response to therapy as well as for disease evolution. Furthermore, we are analyzing the cfDNA and CTCs of the patients at different time points to investigate their use in monitoring minimal residual disease and disease progression. Conclusion. The combination of ixazomib, lenalidomide, and dexamethasone is an effective and well-tolerated intervention in high-risk smoldering myeloma. The high response rate, convenient schedule with minimal toxicity observed to date are promising in this patient population at high risk of progression to symptomatic disease. Further studies and longer follow up for disease progression are warranted. Disclosures Bustoros: Dava Oncology: Honoraria. Munshi:OncoPep: Other: Board of director. Anderson:C4 Therapeutics: Equity Ownership; Celgene: Consultancy; Bristol Myers Squibb: Consultancy; Takeda Millennium: Consultancy; Gilead: Membership on an entity's Board of Directors or advisory committees; Oncopep: Equity Ownership. Richardson:Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Oncopeptides: Membership on an entity's Board of Directors or advisory committees; Karyopharm: Membership on an entity's Board of Directors or advisory committees; Jazz Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Membership on an entity's Board of Directors or advisory committees; BMS: Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees, Research Funding. Ghobrial:Celgene: Consultancy; Takeda: Consultancy; Janssen: Consultancy; BMS: Consultancy.

The Interaction of Bortezomib with P-Gp, MRP-1 and BCRP Drug Transporters: Implications for Therapeutic Applications of Bortezomib in Advanced Multiple Myeloma and Other Neoplasias.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 1729-1729
Author(s):  
Melissa G Ooi ◽  
Robert O'Connor ◽  
Jana Jakubikova ◽  
Justine Meiller ◽  
Steffen Klippel ◽  
...  
Keyword(s):  
Lung Cancer ◽  
Multiple Myeloma ◽  
Cell Line ◽  
Board Of Directors ◽  
Cell Lines ◽  
Research Funding ◽  
Significant Activity ◽  
Cancer Resistance ◽  
Advisory Committees ◽  
Bortezomib Treatment

Abstract Abstract 1729 Poster Board I-755 Background Multidrug transporters are energy-dependent transmembrane proteins which can efflux a broad range of anticancer drugs and thereby play a role in resistance to the actions of substrate agents. Classically, three transporters, p-glycoprotein (Pgp; MDR-1; ABCB1), multidrug resistant protein-1 (MRP-1; ABCC1) and breast cancer resistance protein (BCRP; MXR; ABCG2), have been found to have the broadest substrate specificity and a strong correlation with drug resistance in vitro and in vivo in many models and forms of cancer. We have sought to characterize the interaction of bortezomib with these transporters and thereby explore the potential for these agents to play a role in resistance. Bortezomib is a novel proteosome inhibitor with significant activity in multiple myeloma, although subsets of patients remain refractory to the activity of the drug. Hence, better characterization of the interactions of this drug with classical resistance mechanisms may identify improved treatment applications. Methods and Results We investigated the role of these transporters by using isogenic cell line models which are resistant due to overexpression of a particular transporter: DLKP lung cancer cell line that overexpresses MRP-1; DLKP-A which overexpresses Pgp; and DLKP-SQ-Mitox which overexpresses BCRP. DLKP-A cells exhibited a 4.6-fold decrease in responsiveness to bortezomib compared to parental DLKP cells. In DLKP-SQ-Mitox, bortezomib-induced cytotoxicity was comparable to DLKP. When bortezomib was combined with elacridar, a Pgp and BCRP inhibitor, significant synergy was evident in DLKP-A (100% viable cells with single agent treatment versus 11% with the combination), but not DLKP-SQ-Mitox. Sulindac, an MRP-1 inhibitor, combined with bortezomib failed to produce any synergy in MRP-1 positive DLKP cells. Conversely, combination assays of Pgp substrate cytotoxics such as doxorubicin with Bortezomib were largely additive in nature. This indicates that bortezomib has little, if any, direct Pgp inhibitory activity, as combinations of a traditional Pgp inhibitor (such as elacridar) and doxorubicin would show marked synergy rather than just an additive effect in Pgp positive cells. To further characterize the extent of this interaction with Pgp, we conducted cytotoxicity assays in cell lines with varying levels of Pgp overexpression. NCI/Adr-res (ovarian cancer, high Pgp overexpression), RPMI-Dox40 (multiple myeloma, moderate Pgp overexpression) and A549-taxol (lung cancer, low Pgp overexpression). The combination of bortezomib and elacridar that produced the most synergy was in cell lines expressing moderate to high levels of Pgp expression. Cell lines with lower Pgp expression produced an additive cytotoxicity. We next examined whether bortezomib had any direct effect on Pgp expression. In RPMI-Dox40 cells, Pgp expression is reduced in a time-dependent manner with bortezomib treatment. Conclusions Our studies therefore show that bortezomib is a substrate for Pgp but not the other drug efflux pumps. In tumor cells expressing high levels of Pgp, the efficacy of bortezomib is synergistically enhanced by combinations with a Pgp inhibitor, while bortezomib treatment itself can reduce the expression of Pgp. This study suggests that in the subset of patients with advanced multiple myeloma or solid tumors which express high levels of Pgp, inhibition of its function could contribute to enhanced responsiveness to bortezomib. Disclosures Richardson: millenium: Membership on an entity's Board of Directors or advisory committees, Research Funding; celgene: Membership on an entity's Board of Directors or advisory committees, speakers bureau up to 7/1/09; MLNM: speakers bureau up to 7/1/09. Mitsiades:Millennium Pharmaceuticals : Consultancy, Honoraria; Novartis Pharmaceuticals : Consultancy, Honoraria; Bristol-Myers Squibb : Consultancy, Honoraria; Merck &Co: Consultancy, Honoraria; Kosan Pharmaceuticals : Consultancy, Honoraria; Pharmion: Consultancy, Honoraria; PharmaMar: licensing royalties ; Amgen Pharmaceuticals: Research Funding; AVEO Pharma: Research Funding; EMD Serono : Research Funding; Sunesis Pharmaceuticals: Research Funding. Anderson:Celgene: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Millennium: Consultancy, Research Funding; Biotest AG: Consultancy, Research Funding.

Phase 1/2 Study of Elotuzumab in Combination with Bortezomib in Patients with Multiple Myeloma with One to Three Prior Therapies: Interim Results.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 3876-3876 ◽  
Author(s):  
Andrzej J Jakubowiak ◽  
William Bensinger ◽  
David Siegel ◽  
Todd M. Zimmerman ◽  
Jan M. Van Tornout ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Bone Marrow ◽  
Clinical Response ◽  
Board Of Directors ◽  
Research Funding ◽  
Mononuclear Cells ◽  
Phase 1 ◽  
Surface Glycoprotein ◽  
Advisory Committees ◽  
Cell Surface Glycoprotein

Abstract Abstract 3876 Poster Board III-812 Background Elotuzumab is a humanized monoclonal IgG1 antibody directed against CS1, a cell surface glycoprotein, which is highly and uniformly expressed in multiple myeloma (MM). In mouse xenograft models of MM, elotuzumab demonstrated significantly enhanced anti-tumor activity when combined with bortezomib compared to bortezomib alone (Van Rhee et al., Mol. Cancer Ther., in press, 2009). This phase 1/2 trial will determine the maximum tolerated dose (MTD), overall safety, pharmacokinetics (PK) and clinical response of elotuzumab in combination with bortezomib in patients with relapsed MM following 1-3 prior therapies. Methods The study consists of 4 escalating cohorts of elotuzumab (2.5 mg/kg to 20 mg/kg) administered on Days 1 and 11 and bortezomib (1.3 mg/m2) administered on Days 1, 4, 8 and 11 of a 21-day cycle. Patients with progressive disease at the end of Cycle 2 or 3 also receive oral dexamethasone (20 mg) on Days 1, 2, 4, 5, 8, 9, 11 and 12 of each subsequent cycle. Patients with stable disease or better at the end of 4 cycles will continue treatment for 6 or more cycles unless withdrawn earlier due to unexpected toxicity or disease progression. Key entry criteria: age ≥ 18 years; confirmed diagnosis of MM and documentation of 1 to 3 prior therapies; measurable disease M-protein component in serum and/or in urine; and no prior bortezomib treatment within 2 weeks of first dose. Results To date, a total of 16 MM patients with a median age of 64 years have been enrolled in the study. The median time from initial diagnosis of MM was 3.5 years and patients had received a median of 2 prior MM treatments. Patients have been treated in four cohorts; 3 each in 2.5, 5 and 10 mg/kg elotuzumab cohorts, and 7 in the 20 mg/kg elotuzumab cohort. No dose limiting toxicity (DLT) was observed during the first cycle of the study and the MTD was not established. Five SAEs have been reported in four patients in later treatment cycles; two events, chest pain and gastroenteritis, occurring in one patient, were considered elotuzumab-related. Other SAEs include grade 3 sepsis, vomiting, pneumonia and grade 2 dehydration. The most common AEs reported include Grade 1-3 diarrhea, constipation, nausea, fatigue, thrombocytopenia, neutropenia, anemia and peripheral neuropathy. The best clinical response (EBMT criteria) for the 16 patients who have received at least two cycles of treatment is shown in the table below. Preliminary PK analysis suggests a serum half-life of 10-11 days at higher doses (10 and 20 mg/kg). Preliminary analysis of peripheral blood mononuclear cells and bone marrow of patients on study indicates that objective responses in the study correlate well with complete saturation of CS1 sites by elotuzumab on bone marrow plasma and NK cells. Conclusions The combination of elotuzumab with bortezomib has a manageable adverse event profile and shows promising preliminary efficacy with ≥PR in 44% and ≥MR in 75% of all enrolled patients. Accrual is ongoing in the expanded 20 mg/kg cohort. Updated safety, efficacy, and PK data will be presented at the meeting. Disclosures: Jakubowiak: Millennium: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Centocor Ortho Biotech: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Exelixis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; BMS: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Off Label Use: Bortezomib in combination with elotuzumab for the treatment of relapsed/refractory multiple myeloma. Bensinger:Millennium: Membership on an entity's Board of Directors or advisory committees. Siegel:Millennium: Speakers Bureau; Celgene: Speakers Bureau. Zimmerman:Millennium: Speakers Bureau; Centecor: Speakers Bureau. Van Tornout:BMS: Employment. Zhao:Facet Biotech: Employment. Singhal:Facet Biotech: Employment. Anderson:Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Millennium: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding.

Dual Targeting of -TORC1 and -TORC2 as a New Strategy In the Treatment of Multiple Myeloma

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 133-133 ◽  
Author(s):  
Patricia Maiso ◽  
AbdelKareem Azab ◽  
Yang Liu ◽  
Yong Zhang ◽  
Feda Azab ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Multiple Myeloma ◽  
Bone Marrow ◽  
Board Of Directors ◽  
Cell Lines ◽  
Mechanism Of Action ◽  
Plasma Cells ◽  
Bone Marrow Microenvironment ◽  
Advisory Committees

Abstract Abstract 133 Introduction: Mammalian target of rapamycin (mTOR) is a downstream serine/threonine kinase of the PI3K/Akt pathway that integrates signals from the tumor microenvironment such as cytokines and growth factors, nutrients and stresses to regulate multiple cellular processes, including translation, autophagy, metabolism, growth, motility and survival. Mechanistically, mTOR operates in two distinct multi-protein complexes, TORC1 and TORC2. Activation of TORC1 leads to the phosphorylation of p70S6 kinase and 4E-BP1, while activation of TORC2 regulates phosphorylation of Akt and other AGC kinases. In multiple myeloma (MM), PI3K/Akt plays an essential role enhancing cell growth and survival and is activated by the loss of the tumor suppressor gene PTEN and by the bone marrow microenvironment. Rapamycin analogues such as RAD001 and CCI-779 have been tested in clinical trials in MM. Their efficacy as single agents is modest, but when used in combination, they show higher responses. However, total inhibition of Akt and 4E-BP1 signaling requires inactivation of both complexes TORC1 and TORC2. Consequently, there is a need for novel inhibitors that can target mTOR in both signaling complexes. In this study we have evaluated the role of TORC1 and TORC2 in MM and the activity and mechanism of action of INK128, a novel, potent, selective and orally active small molecule TORC1/2 kinase inhibitor. Methods: Nine different MM cell lines and BM samples from MM patients were used in the study. The mechanism of action was investigated by MTT, Annexin V, cell cycle analysis, Western-blotting and siRNA assays. For the in vivo analyses, Luc+/GFP+ MM.1S cells (2 × 106/mouse) were injected into the tail vein of 30 SCID mice and tumor progression was detected by bioluminescence imaging. Nanofluidic proteomic immunoassays were performed in selected tumors. Results: To examine activation of the mTOR pathway in MM, we performed kinase activity assays and protein analyses of mTOR complexes and its downstream targets in nine MM cell lines. We found mTOR, Akt, pS6R and 4E-BP1 are constitutively activated in all cell lines tested independently of the status of Deptor, PTEN, and PI3K. All cell lines expressed either Raptor, Rictor or both; excepting H929 and U266LR7 which were negative for both of them. Moreover, primary plasma cells from several MM patients highly expressed pS6R while normal cells were negative for this protein. We found that INK128 and rapamycin effectively suppressed phosphorylation of p6SR, but only INK128 was able to decrease phosphorylation of 4E-BP1. We observed that INK128 fully suppressed cell viability in a dose and time dependent manner, but rapamycin reached a plateau in efficacy at ± 60%. The IC50 of INK128 was in the range of 7.5–30 nM in the eight cell lines tested. Similar results were observed in freshly isolated plasma cells from MM patients. Besides the induction of apoptosis and cell cycle arrest, INK128 was more potent than rapamycin to induce autophagy, and only INK128 was able to induce PARP and Caspases 3, 8 and 9 cleavage. In the bone marrow microenvironment context, INK128 inhibited the proliferation of MM cells and decreased the p4E-BP1 induction. Importantly, treatment with rapamycin under such conditions did not affect cell proliferation. INK128 also showed a significantly greater effect inhibiting cell adhesion to fibronectin OPM2 MM1S, BMSCs and HUVECs compared to rapamycin. These results were confirmed in vivo. Oral daily treatment of NK128 (1.0 mg/kg) decreased tumor growth and improved survival of mice implanted with MM1S. Conclusion: Dual inhibition of TORC1 and TORC2 represent a new and promising approach in the treatment of MM and its microenvironment. The ability of INK128 to inhibit both TORC1 and TORC2 strongly supports the potential use of this compound in MM patients. Disclosures: Anderson: Millennium Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Ghobrial:Celgene: Membership on an entity's Board of Directors or advisory committees; Millennium: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees.

Multiple Myeloma In Complete Remission After Autologous Stem Cell Transplantation: Impact of Bone Marrow Plasma Cell Assessment by Conventional Morphology on Disease Progression

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 2946-2946
Author(s):  
Carlos Fernández de Larrea ◽  
Natalia Tovar ◽  
María Rozman ◽  
Laura Rosiñol ◽  
Juan I. Aróstegui ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Bone Marrow ◽  
Stem Cell ◽  
Complete Remission ◽  
Board Of Directors ◽  
Research Funding ◽  
Bone Marrow Aspirate ◽  
Advisory Committees ◽  
Bone Marrow Plasma ◽  
Serum And Urine

Abstract Abstract 2946 Background: The achievement of complete remission (CR) is the crucial step for a long-lasting response and prolonged survival after autologous stem cell transplantation (ASCT) in patients with multiple myeloma (MM). The European Group for Blood and Marrow Transplantation (EBMT) criteria for CR include the negativity of serum and urine immunofixation (IFE) and less than 5% of bone marrow plasma cells (BMPCs). Additionally, the International Myeloma Working Group (IMWG) has even proposed a stringent CR category, which requires to rule out the clonal nature of the BMPCs. However, few studies have addressed this issue in patients with MM and negative IFE. The aim of the present study was to determine the impact of plasma cell count in the bone marrow aspirate on the long-term outcome of patients with MM with negative IFE after ASCT. Methods: Thirty-five patients (16M/19F; median age at ASCT 55 years, range 26–68) with MM who underwent ASCT from March 1994 to December 2008, were studied. All patients had achieved a negative serum and urine IFE after high dose therapy with melphalan-based regimens. Bone marrow aspirate was performed when negative serum and urine IFE was achieved and at least three months from ASCT (median 3.24 months). The analysis was based on microscopic revision for May-Grünwald-Giemsa stained bone marrow smears performed according to standard procedures. BMPC percentage was calculated independently by two observers counting 500 bone marrow total nucleated cells in random areas from two different slides (1000 cells on each patient). Results: Median BMPCs percentage was 0.8 (range 0.1–5.8). Only two patients had more than 3% BPMCs. These results are in contrast with a recent report from the Mayo Clinic group, where 14% of the patients with MM and negative IFE had 5% or more BMPCs. In univariate Cox-model regression analysis, the number of BMPCs significantly correlated with progression-free survival (PFS)(p=0.021) with no impact on overall survival (OS)(p=0.92). This statistical significance on PFS was retained in the multivariate analysis, when baseline prognostic factors such as age, hemoglobin level, serum creatinine, β2-microglobulin and Durie-Salmon stage were added to the model (p=0.003). To establish the best predictive cut-off for progression and survival, a receptor-operator curve (ROC) analysis was developed. It showed the value of 1.5% BMPCs, with a sensitivity of 53%, specificity of 90% and area under the curve of 0.66 for predicting progression. Ten patients had more than 1.5% BMPC, and 25 equal or less than 1.5% BMPC. Median PFS was 8.5 years (CI 95% 2.6 to 14.3) and was not reached in patients with ≤1.5% BMPCs versus 3.1 years in patients with >1.5% BMPCs, with a hazard ratio probability to progression of 3.02 (CI 95% 1.18 to 9.71)(p=0.016) in the group with more than 1.5% of BMPCs (Figure 1). Median OS was not reached in patients with ≤1.5% compared with a median of 9.7 years in those with more than 1.5% BMPCs (p=0.195) (Figure 2). It is likely that serological CR with very low percentage of BMPCs (i.e. ≤1.5%) is equivalent to negative MRD assessed by MFC or molecular studies. In fact, all 8 patients in continued CR between 9 and 16 years beyond ASCT (“operational cures”) are in the group with ≤1.5% BMPCs, while all patients in the group with >1.5% BPMC have relapsed within the first 9 years from ASCT (Figure 1). Conclusion: The percentage of BMPCs in patients with MM in CR after ASCT is a strong predictor of progression. Bone marrow morphology examination is an easy, inexpensive, and non-time consuming test and it should be the first step in the estimation of the residual tumor mass in patients with MM in CR after ASCT. Disclosures: Rosiñol: Janssen-Cilag: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees. Cibeira:Janssen-Cilag: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees. Blade:Janssen-Cilag: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding.

CYC065, a Potent Derivative of Seliciclib Is Active In Multiple Myeloma In Preclinical Studies

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 2999-2999 ◽  
Author(s):  
Samantha Pozzi ◽  
Diana Cirstea ◽  
Loredana Santo ◽  
Doris M Nabikejje ◽  
Kishan Patel ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Multiple Myeloma ◽  
Cell Line ◽  
Board Of Directors ◽  
Cell Lines ◽  
Preliminary Data ◽  
Research Funding ◽  
Preclinical Studies ◽  
Dependent Manner ◽  
Advisory Committees

Abstract Abstract 2999 Multiple myeloma (MM) is a treatable but incurable hematological malignancy and novel targeted therapies are under investigation. MM is characterized by dysregulation of the cell cycle, consequent to the overexpression of cyclins and their related kinases, the cyclins dependent kinases (CDK), a group of Ser/Thr proteine kinases. CDKs represent a promising therapeutic target, and inhibitors have been developed for anticancer treatment. We have previously studied seliciclib in the context of MM. CYC065, a second generation CDK inhibitor is the more potent derivative of seliciclib. It is mainly active on CDK 2, 5 and 9, involved in progression of the cell cycle and protein transcription. It has already shown promising results in preclinical studies in breast cancer and acute leukemia. We tested CYC065 in in vitro experiments in MM. Our preliminary data in 7 MM cell lines showed cytotoxicity of CYC065, both in MM cell lines sensitive as well as resistant to conventional chemotherapy, with an IC50 ranging between 0.06 and 2μ M, at 24 and 48h. Tritiated thymidine uptake assay confirmed the antiproliferative effects of CYC065 in MM, and its ability to overcome the growth advantage conferred by co-culture with bone marrow stromal cells derived from MM patients, and cytokines like interleukin 6 (10ng/ml) and insulin like growth factor-1 (50ng/ml). The anti-proliferative effect was evident both at 24 and 48h, starting at concentrations as low as 0.015μ M. The AnnexinV/PI assay in the MM1.s cell line confirmed CYC065's ability to induce apoptosis in a time dependent manner starting at 9 hours of treatment, at a concentration of 0.125 μ M, inducing 82% of apoptosis after 48h of exposure. Cell cycle analysis in the same MM1.s cell line showed an increase of subG1 phase, starting at 9 hours of treatment, at 0.125 μ M of CYC065. Preliminary results of western blot analysis confirmed the apoptotic effect of CYC065 in the MM1s cell line, highlighted by the cleavage of caspase 3, 8, 9 and PARP. The compound was tested in primary CD138+ cells isolated from three refractory MM patients, confirming its efficacy at 0.125 μ M, both at 24 and 48h. Comparative analysis in PBMCs from normal donors, for the evaluation of the drug toxicity is ongoing and will be presented. In conclusion our preliminary data confirm the efficacy of CYC065 in MM cell lines and primary MM cells, at nanomolar concentrations. Ongoing mechanistic and in vivo studies will delineate its role in the now increasing spectrum of CDK inhibitors in MM and better define its potential for clinical development in MM. Disclosures: Green: Cyclacel: Employment. Anderson:Millennium Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Scadden:Fate Therapeutics: Consultancy, Equity Ownership, Patents & Royalties. Raje:Celgene: Membership on an entity's Board of Directors or advisory committees; Astra Zeneca: Research Funding; Acetylon: Research Funding.

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