The association of diabetes and anti-diabetic medications with clinical outcomes in multiple myeloma.

BACKGROUND: Insulin/insulin-like growth factor-1 signalling may underlie the promoting effect of type 2 diabetes on cancer. This study examined the association of diabetes, including steroid-induced diabetes (SID), and the impact of anti-diabetic medication on clinical outcomes of multiple myeloma (MM). METHODS: A retrospective review was conducted of 1240 MM patients. Overall survival (OS) and MM disease status prior to death were analysed. RESULTS: Diabetic patients had a significantly shorter OS than non-diabetic patients (median: 65.4 vs 98.7 months). In multivariate analysis, SID was a significant predictor of decreased OS, along with age, comorbidity, MM stage, and cytogenetic abnormalities. Analyzing only the diabetic MM patients, Cox regression showed that metformin predicted an increased OS, whereas use of insulin/analogues predicted a decreased OS. Competing risk analysis showed that DM was associated with increased cumulative incidence of death with progressive MM. Among the diabetics, multivariate regression showed that insulin/analogues were associated with increased, but metformin with decreased death with progressive MM. Potential immortal time bias was evaluated by landmark analyses. CONCLUSIONS: DM, SID in particular, is associated with poor clinical outcomes in MM. Insulin/analogues are associated with poor outcomes, whereas metformin is associated with improved outcomes. No conclusion about causal relationships can be made at this time. Managing hyperglycaemia with non-insulin regimens should be investigated in randomised trials.

Hyperfractionated Cyclophosphamide and Dexamethasone Alone or in Combination with Daratumumab and/or Carfilzomib for the Treatment of Relapsed or Refractory Multiple Myeloma: A Single-Center Retrospective Analysis.

BACKGROUND: Hyperfractionated cyclophosphamide and dexamethasone (HyperCd) alone, or with carfilzomib(K) and/or daratumumab(D), represents a potential treatment option when rapid disease control is needed for patients with aggressive presentations of relapsed/refractory multiple myeloma (RRMM). PATIENTS AND METHODS: This is a single-center, retrospective analysis of adult patients with RRMM who received HyperCd with or without K and/or D between May 1, 2016 and August 1, 2019 at the University of Texas MD Anderson Cancer Center. We here report treatment response and safety outcomes. RESULTS: Data from 97 patients, 12 with plasma cell leukemia (PCL), were reviewed in this analysis. Patients had had a median of 5 prior lines of therapy and received a median of 1 consecutive cycle of hyperCd-based therapy. The overall response rate (ORR) of all patients was 71.8% (HyperCd 75%, HyperCdK 64.3%, D-HyperCd 73.3%, and D-HyperCdK 76.9%). Median progression-free survival and overall survival among all patients was 4.3 months (HyperCd 3.1 months, HyperCdK 4.5 months, D-HyperCd 3.3 months, and D-HyperCdK 6 months) and 9.0 months (HyperCd 7.4 months, HyperCdK 9.0 months, D-HyperCd 7.5 months, and D-HyperCdK 15.2 months), respectively. Grade 3/4 hematologic toxicities were common, thrombocytopenia being the most frequent at 76%. Notably, 29-41% of patients per treatment group had existing grade 3/4 cytopenias at initiation of hyperCd-based therapy. CONCLUSION: HyperCd-based regimens provided rapid disease control among MM patients, even when heavily pre-treated and with few remaining treatment options. Grade 3/4 hematologic toxicities were frequent, but manageable with aggressive supportive care.

A randomized trial of a single-dose rasburicase versus five-daily doses in patients at risk for tumor lysis syndrome.

BACKGROUND: Tumor lysis syndrome (TLS) is a life-threatening disorder characterized by hyperuricemia and metabolic derangements. The efficacy of rasburicase, administered daily for 5 days, has been well established. However, the optimal duration of therapy is unknown in adults. PATIENTS AND METHODS: We evaluated the efficacy of rasburicase (0.15 mg/kg) administered as single dose followed by as needed dosing (maximum five doses) versus daily dosing for 5 days in adult patients at risk for TLS. RESULTS: Eighty of the 82 patients enrolled received rasburicase; 40 high risk [median uric acid (UA) 8.5 mg/dl; range, 1.5-19.7] and 40 potential risk (UA = 5.6 mg/dl; range, 2.4-7.4). Seventy-nine patients (99%) experienced normalization in their UA within 4 h after the first dose; 84% to an undetectable level (<0.7 mg/dl). Thirty-nine of 40 (98%) patients in the daily-dose arm and 34 of 40 (85%) patients in single-dose arm showed sustained UA response. Six high-risk patients within the single-dose arm required second dose for UA >7.5 mg/dl. Rasburicase was well tolerated; one patient with glucose-6-phosphate dehydrogenase deficiency developed methemoglobinemia and hemolysis. CONCLUSIONS: Rasburicase is highly effective for prevention and management of hyperuricemia in adults at risk for TLS. Single-dose rasburicase was effective in most patients; only a subset of high-risk patients required a second dose.

Correction: Management of relapsed and refractory multiple myeloma: novel agents, antibodies, immunotherapies and beyond.

Following the publication of this article the authors noted that the MRD data under the Table 1 column "Remark" of Aspire should go to that of Pollux. The authors wish to apologize for any inconvenience caused. The corrected table is attached to this correction.

Management of relapsed and refractory multiple myeloma: novel agents, antibodies, immunotherapies and beyond.

Despite enormous advances, management of multiple myeloma (MM) remains challenging. Multiple factors impact the decision to treat or which regimen to use at MM relapse/progression. Recent major randomized controlled trials (RCTs) showed widely varying progression-free survivals (PFS), ranging from a median of 4 months (MM-003) to 23.6 months (ASPIRE). Based on these RCTs, next-generation proteasome inhibitors (carfilzomib and ixazomib), next-generation immunomodulatory agent (pomalidomide), and monoclonal antibodies (elotuzumab and daratumumab) were approved for relapsed and refractory MM. Daratumumab, targeting CD38, has multiple mechanisms of action including modulation of the immunosuppressive bone marrow micro-environment. In addition to the remarkable single agent activity in refractory MM, daratumumab produced deep responses and superior PFS in MM when combined with lenalidomide/dexamethasone, or bortezomib/dexamethasone. Other anti-CD38 antibodies, such as isatuximab and MOR202, are undergoing assessment. Elotuzumab, targeting SLAMF7, yielded superior response rates and PFS when combined with lenalidomide/dexamethasone. New combinations of these next generation novel agents and/or antibodies are undergoing clinical trials. Venetoclax, an oral BH3 mimetic inhibiting BCL2, showed single agent activity in MM with t(11;14), and is being studied in combination with bortezomib/dexamethasone. Selinexor, an Exportin-1 inhibitor, yielded promising results in quad- or penta-refractory MM including patients resistant to daratumumab. Pembrolizumab, an anti-PD1 check-point inhibitor, is being tested in combination with lenalidomide/dexamethasone or pomalidomide/dexamethasone. Chimeric antigen receptor-T cells targeting B-cell maturation antigen have yielded deep responses in RRMM. Finally, salvage autologous stem cell transplantation (ASCT) remains an important treatment in MM relapsing/progressing after a first ASCT. Herein, the clinical trial data of these agents are summarized, cautious interpretation of RCTs highlighted, and algorithm for salvage treatment of relapse/refractory MM proposed.

Concordant bone marrow involvement of diffuse large B-cell lymphoma represents a distinct clinical and biological entity in the era of immunotherapy.

In diffuse large B-cell lymphoma (DLBCL), the clinical and biological significance of concordant and discordant bone marrow (BM) involvement have not been well investigated. We evaluated 712 de novo DLBCL patients with front-line rituximab-containing treatment, including 263 patients with positive and 449 with negative BM status. Compared with negative BM disease, concordant BM adversely impacted overall and progression-free survival, independent of the International Prognostic Index (IPI) and cell-of-origin classification. Once BM is concordantly involved, poor prognosis was not associated with the extent of BM involvement. Conversely, patients with discordant BM showed favorable overall survival similar to stage I-II DLBCL. A BM-adjusted IPI, using three parameters: concordant BM involvement, age >60 years, and performance status >1, improves the risk stratification for DLBCL with positive BM. Intensive immunochemotherapy seemingly rendered survival benefit for patients with concordant BM, as did rituximab maintenance for the discordant BM group. Frequently revealing adverse clinical and molecular characteristics, patients with concordant BM demonstrated gene expression signatures relevant to tumor cell proliferation, migration and immune escape. In conclusion, clinical and biological heterogeneity is seen in DLBCL with positive BM but concordant BM involvement represents a distinct subset with unfavorable gene signatures, high-risk clinicopathologic features and poor prognosis.

Tumor growth inhibition induced in a murine model of human Burkitt's lymphoma by a proteasome inhibitor.

Cell growth and viability are dependent on the function of the multicatalytic proteinase complex (proteasome), a multisubunit particle that affects progression through the mitotic cycle by degradation of cyclins. Exposure of rodent fibroblasts and human lymphoblasts in culture to benzyloxycarbonyl-leucyl-leucyl-phenylalaninal (Z-LLF-CHO), a cell-permeable peptidyl aldehyde inhibitor of the chymotrypsin-like activity of the proteasome, resulted in the induction of apoptosis in a rapid, dose-dependent fashion. Fibroblasts transformed with ras and myc, lymphoblasts transformed by c-myc alone, and a Burkitt's lymphoma (BL) cell line that overexpresses c-Myc were up to 40-fold more susceptible to apoptosis than were either primary rodent fibroblasts or immortalized nontransformed human lymphoblasts, respectively. To determine whether such preferential apoptosis could impact upon tumor growth in vivo, toxicological studies were performed in mice with severe combined immunodeficiency and showed that mice tolerated single interscapular doses of Z-LLF-CHO without unacceptable toxicity. Severe combined immunodeficient mice bearing s.c. BL tumors in the flank were treated interscapularly with Z-LLF-CHO or a comparable dose of the peptidyl alcohol (Z-LLF-OH), which does not induce proteasome inhibition or apoptosis. Single doses of Z-LLF-CHO induced statistically significant (P < 0.0001) early tumor regression and a significant (P < 0.0001) delay in tumor progression. Analysis of tumor specimens revealed increased apoptosis in BL tumors from mice treated with Z-LLF-CHO. These results, showing a 42% tumor growth delay, indicate that proteasome inhibitors have the potential of curbing the growth of a c-myc-related tumor.

Tumor induction by the c-Myc target genes rcl and lactate dehydrogenase A.

The characterization of c-Myc target genes, such as rcl and lactate dehydrogenase A (LDH-A), is critical for understanding the mechanisms of c-Myc-induced cell transformation and tumorigenesis. We have previously demonstrated that Rcl induces anchorage-independent growth in Ratla fibroblasts and that LDH-A is required for cell transformation by c-Myc. In this study, we report that Rcl and LDH-A act synergistically to induce anchorage-independent growth. Cells expressing both Rcl and LDH-A form tumors after s.c. injection into nude mice, although neither Rcl or LDH-A overexpression alone induces tumorigenesis. The inability of Rcl and LDH-A to fully recapitulate c-Myc activity, however, indicates that other c-Myc target genes participate in tumorigenesis. In addition, cells that coexpress Rcl and vascular endothelial growth factor are more comparable with c-Myc overexpressing cells in their ability to form tumors in nude mice. These findings confirm Rcl and LDH-A as critical components of the cell transformation program induced by c-Myc and suggest that Rcl is tumorigenic in cells that are provided with a permissive metabolic milieu.

Siltuximab (CNTO 328) with lenalidomide, bortezomib and dexamethasone in newly-diagnosed, previously untreated multiple myeloma: an open-label phase I trial.

The safety and efficacy of siltuximab (CNTO 328) was tested in combination with lenalidomide, bortezomib and dexamethasone (RVD) in patients with newly-diagnosed, previously untreated symptomatic multiple myeloma. Fourteen patients were enrolled in the study, eleven of whom qualified to receive therapy. A majority of patients (81.8%) completed the minimal number or more of the four required cycles, while two patients completed only three cycles. The maximum tolerated dose (MTD) of siltuximab with RVD was dose level -1 (siltuximab: 8.3 mg/kg; bortezomib: 1.3 mg/m(2); lenalidomide: 25 mg; dexamethasone: 20 mg). Serious adverse events were grade 3 pneumonia and grade 4 thrombocytopenia, and no deaths occurred during the study or with follow-up (median follow-up 28.1 months). An overall response rate, after 3-4 cycles of therapy, of 90.9% (95% confidence interval (CI): 58.7%, 99.8%) (9.1% complete response (95% CI: 0.2%, 41.3%), 45.5% very good partial response (95% CI: 16.7%, 76.6%) and 36.4% partial response (95% CI: 10.9%, 69.2%)) was seen. Two patients withdrew consent, and nine patients (81.8%) opted for autologous stem cell transplantation.

Management of relapsed multiple myeloma: recommendations of the International Myeloma Working Group.

The prognosis for patients multiple myeloma (MM) has improved substantially over the past decade with the development of new, more effective chemotherapeutic agents and regimens that possess a high level of anti-tumor activity. In spite of this important progress, however, nearly all MM patients ultimately relapse, even those who experience a complete response to initial therapy. Management of relapsed MM thus represents a vital aspect of the overall care for patients with MM and a critical area of ongoing scientific and clinical research. This comprehensive manuscript from the International Myeloma Working Group provides detailed recommendations on management of relapsed disease, with sections dedicated to diagnostic evaluation, determinants of therapy, and general approach to patients with specific disease characteristics. In addition, the manuscript provides a summary of evidence from clinical trials that have significantly impacted the field, including those evaluating conventional dose therapies, as well as both autologous and allogeneic stem cell transplantation. Specific recommendations are offered for management of first and second relapse, relapsed and refractory disease, and both autologous and allogeneic transplant. Finally, perspective is provided regarding new agents and promising directions in management of relapsed MM.

The role of the ubiquitin-proteasome pathway in apoptosis.

Coordinated intracellular protein degradation mediated by the ubiquitin-proteasome pathway is crucial to a vast array of cellular processes including orderly progression through the mitotic cycle. Similarly important to both the fates of individual cells, as well as to the normal function of multicellular organisms, is the process of apoptosis, or programmed cell death. Execution of this latter process has been known for some time to be intimately associated with the activity of caspases, a family of proteases related to interleukin-1-beta-converting enzyme. Evidence is now accumulating, however, that the ubiquitin-proteasome system itself plays an important role in apoptosis, and some of the cellular pathways that are impacted upon by the proteasome, and may lead to apoptosis, are beginning to be dissected. This review provides a summary of the experimental basis by which components of the ubiquitin-proteasome pathway have been linked to apoptosis, and attempts are made to formulate a hypothesis about its role in this process.

High-dose therapy with auto-SCT is feasible in high-risk cardiac amyloidosis.

Cardiac involvement in light-chain amyloidosis (AL) predicts poor prognosis and is associated with higher TRM and morbidity during high-dose therapy and auto-SCT (HDT-ASCT). We studied the outcomes of 30 patients with cardiac amyloidosis undergoing HDT-ASCT at our center between January 1998 and March 2012. The median age of the patients was 53 years (range, 36-74) with a median follow-up of 35 months (range, 0.4-97 months). Twenty-seven patients (90%) had more than one organ involved besides the heart with 37% with cardiac stage ⩾3. Melphalan-based conditioning regimen (140-200 mg/m(2)) was used for HDT-ASCT. One-year TRM is 10%. Three-year OS and EFS from HDT-ASCT was 83% and 56.8%, respectively. Cumulative incidence of relapse at 3 years was 38.5%. Negative factors affecting survival included age >60 years, lack of novel induction therapy and BM plasmacytosis >10%. We conclude that HDT-ASCT is well tolerated in patients with high-risk cardiac amyloidosis and can lead to improved overall outcomes.

Evidence of a role for CD44 and cell adhesion in mediating resistance to lenalidomide in multiple myeloma: therapeutic implications.

Resistance of myeloma to lenalidomide is an emerging clinical problem, and though it has been associated in part with activation of Wnt/ß-catenin signaling, the mediators of this phenotype remained undefined. Lenalidomide-resistant models were found to overexpress the hyaluronan (HA)-binding protein CD44, a downstream Wnt/ß-catenin transcriptional target. Consistent with a role of CD44 in cell adhesion-mediated drug resistance (CAM-DR), lenalidomide-resistant myeloma cells were more adhesive to bone marrow stroma and HA-coated plates. Blockade of CD44 with monoclonal antibodies, free HA or CD44 knockdown reduced adhesion and sensitized to lenalidomide. Wnt/ß-catenin suppression by FH535 enhanced the activity of lenalidomide, as did interleukin-6 neutralization with siltuximab. Notably, all-trans retinoic acid (ATRA) downregulated total ß-catenin, cell-surface and total CD44, reduced adhesion of lenalidomide-resistant myeloma cells and enhanced the activity of lenalidomide in a lenalidomide-resistant in vivo murine xenograft model. Finally, ATRA sensitized primary myeloma samples from patients that had relapsed and/or refractory disease after lenalidomide therapy to this immunomodulatory agent ex vivo. Taken together, our findings support the hypotheses that CD44 and CAM-DR contribute to lenalidomide resistance in multiple myeloma, that CD44 should be evaluated as a putative biomarker of sensitivity to lenalidomide, and that ATRA or other approaches that target CD44 may overcome clinical lenalidomide resistance.

Auto-SCT improves survival in systemic light chain amyloidosis: a retrospective analysis with 14-year follow-up.

Optimal treatment approach continues to remain a challenge for systemic light chain amyloidosis (AL). So far, Auto-SCT is the only modality associated with long-term survival. However, failure to show survival benefit in randomized study raises questions regarding its efficacy. We present a comparative outcome analysis of Auto-SCT to conventional therapies (CTR) in AL patients treated over a 14-year period at our institution. Out of the 145 AL amyloidosis patients, Auto-SCT was performed in 80 patients with 1-year non-relapse mortality rate of 12.5%. Novel agents were used as part of induction therapy in 56% of transplant recipients vs 46% of CTR patients. Hematological and organ responses were seen in 74.6% and 39% in the Auto-SCT arm vs 53% and 12% in the CTR arm, respectively. The projected 5-year survival for Auto-SCT vs CTR was 63% vs 38%, respectively. Landmark analysis of patients alive at 1-year after diagnosis showed improved 5-year OS of 72% with Auto-SCT vs 65% in the CTR arm. In the multivariate analysis, age <60 years, induction therapy with novel agents, kidney only involvement and Auto-SCT were associated with improved survival. In conclusion, Auto-SCT is associated with long-term survival for patients with AL amyloidosis.

Modified high-dose melphalan and autologous SCT for AL amyloidosis or high-risk myeloma: analysis of SWOG trial S0115.

We designed a trial using two sequential cycles of modified high-dose melphalan at 100 mg/m(2) and autologous SCT (mHDM/SCT) in AL amyloidosis (light-chain amyloidosis, AL), AL with myeloma (ALM) and host-based high-risk myeloma (hM) patients through SWOG-0115. The primary objective was to evaluate OS. From 2004 to 2010, 93 eligible patients were enrolled at 17 centers in the United States (59 with AL, 9 with ALM and 25 with hM). The median OS for patients with AL and ALM was 68 months and 47 months, respectively, and has not been reached for patients with hM. The median PFS for patients with AL and ALM was 38 months and 16 months, respectively, and has not been reached for patients with hM. The treatment-related mortality (TRM) was 12% (11/93) and was observed only in patients with AL after SCT. Grade 3 and higher non-hematologic adverse events were experienced by 81%, 67% and 57% of patients with AL, ALM and hM, respectively, during the first and second HDM/SCT. This experience demonstrates that with careful selection of patients and use of mHDM for SCT in patients with AL, ALM and hM, even in the setting of a multicenter study, OS can be improved with acceptable TRM and morbidity.

Treatment outcomes in patients with relapsed and refractory multiple myeloma and high-risk cytogenetics receiving single-agent carfilzomib in the PX-171-003-A1 study.

Several cytogenetic abnormalities are associated with poor outcomes in multiple myeloma (MM). We prospectively analyzed the impact of cytogenetic abnormalities on outcomes during the phase 2 PX-171-003-A1 study of single-agent carfilzomib for relapsed and refractory MM. In the response-evaluable population (257/266), fluorescence in situ hybridization (FISH)/conventional cytogenetic profiles were available for 229 patients; 62 (27.1%) had high-risk cytogenetics--del 17p13, t(4;14) or t(14;16) by interphase FISH or deletion 13 or hypodiploidy by metaphase cytogenetics--and 167 (72.9%) had standard-risk profiles. Generally, baseline characteristics were similar between the subgroups, but International Staging System stage III disease was more common in high- vs standard-risk patients (41.9% vs 27.5%) as was Eastern Cooperative Oncology Group performance status 1/2 (85.5% vs 68.3%). Overall response was comparable between the subgroups (25.8% vs 24.6%, respectively; P=0.85), while time-to-event end points showed a trend of shorter duration in high-risk patients, including median duration of response (5.6 months (95% confidence interval (CI) 3.7-7.8) vs 8.3 months (95% CI 5.6-12.3)) and overall survival (9.3 (95% CI 6.5-13.0) vs 19.0 months (95% CI 15.4-NE); P=0.0003). Taken together, these findings demonstrate that single-agent carfilzomib is efficacious and has the potential to at least partially overcome the impact of high-risk cytogenetics in heavily pre-treated patients with MM.

Plasma cell leukemia: consensus statement on diagnostic requirements, response criteria and treatment recommendations by the International Myeloma Working Group.

Plasma cell leukemia (PCL) is a rare and aggressive variant of myeloma characterized by the presence of circulating plasma cells. It is classified as either primary PCL occurring at diagnosis or as secondary PCL in patients with relapsed/refractory myeloma. Primary PCL is a distinct clinic-pathological entity with different cytogenetic and molecular findings. The clinical course is aggressive with short remissions and survival duration. The diagnosis is based upon the percentage (≥ 20%) and absolute number (≥ 2 × 10(9)/l) of plasma cells in the peripheral blood. It is proposed that the thresholds for diagnosis be re-examined and consensus recommendations are made for diagnosis, as well as, response and progression criteria. Induction therapy needs to begin promptly and have high clinical activity leading to rapid disease control in an effort to minimize the risk of early death. Intensive chemotherapy regimens and bortezomib-based regimens are recommended followed by high-dose therapy with autologous stem cell transplantation if feasible. Allogeneic transplantation can be considered in younger patients. Prospective multicenter studies are required to provide revised definitions and better understanding of the pathogenesis of PCL.

Constitutive activation of p38 MAPK in tumor cells contributes to osteolytic bone lesions in multiple myeloma.

Bone destruction is a hallmark of multiple myeloma and affects more than 80% of patients. However, current therapy is unable to completely cure and/or prevent bone lesions. Although it is accepted that myeloma cells mediate bone destruction by inhibition of osteoblasts and activation of osteoclasts, the underlying mechanism is still poorly understood. This study demonstrates that constitutive activation of p38 mitogen-activated protein kinase in myeloma cells is responsible for myeloma-induced osteolysis. Our results show that p38 is constitutively activated in most myeloma cell lines and primary myeloma cells from patients. Myeloma cells with high/detectable p38 activity, but not those with low/undetectable p38 activity, injected into severe combined immunodeficient (SCID) or SCID-hu mice caused bone destruction. Inhibition or knockdown of p38 in human myeloma reduced or prevented myeloma-induced osteolytic bone lesions without affecting tumor growth, survival, or homing to bone. Mechanistic studies showed that myeloma cell p38 activity inhibited osteoblastogenesis and bone formation and activated osteoclastogenesis and bone resorption in myeloma-bearing SCID mice. This study elucidates a novel molecular mechanism-activation of p38 signaling in myeloma cells-by which myeloma cells induce osteolytic bone lesions, and indicates that targeting myeloma cell p38 may be a viable approach to treating or preventing myeloma bone disease.

Second generation proteasome inhibitors: carfilzomib and immunoproteasome-specific inhibitors (IPSIs).

The ubiquitin-proteasome pathway (UPP) is an attractive chemotherapeutic target due to its intrinsically stringent regulation of cell cycle, pro-survival, and anti-apoptotic regulators that disproportionately favor survival and proliferation in malignant cells. A reversible first-in-class proteasome inhibitor, bortezomib, is Food and Drug Administration approved for multiple myeloma and relapsed/refractory mantle cell lymphoma and has proven to be extremely effective, both as a single agent and in combination. An irreversible second generation proteasome inhibitor, carfilzomib, has shown preclinical effectiveness against hematological and solid malignancies both in vitro and in vivo. Carfilzomib, a peptidyl-epoxyketone functions similarly to bortezomib through primary inhibition of chymotrypsin-like (ChT-L) activity at the b5 subunits of the core 20S proteasome. Carfilzomib is also currently achieving successful response rates within the clinical setting. In addition to conventional proteasome inhibitors, a novel approach may be to specifically target the hematological-specific immunoproteasome, thereby increasing overall effectiveness and reducing negative off-target effects. The immunoproteasome-specific inhibitor, IPSI-001, was shown to have inhibitory preference over the constitutive proteasome, and display enhanced efficiency of apoptotic induction of tumor cells from a hematologic origin. Herein, we discuss the preclinical and clinical development of carfilzomib and explore the potential of immunoproteasome-specific inhibitors, like IPSI-001, as a rational approach to exclusively target hematological malignancies.

Evidence of a role for the novel zinc-finger transcription factor ZKSCAN3 in modulating Cyclin D2 expression in multiple myeloma.

Dysregulation of cyclin D2 contributes to the pathogenesis of multiple myeloma, and can occur through translocations that activate MAF/MAFB or MMSET/FGFR3. However, cyclin D2 induction can also be seen in the absence of such translocations, such as in patients with hyperdiploid disease, through unknown mechanisms. In UniGene cluster data-mining and ECgene analysis, we found that zinc-finger with KRAB and SCAN domains 3 (ZKSCAN3), a novel transcription factor, is overrepresented in this malignancy, and three consensus ZKSCAN3 binding sites were found in the cyclin D2 promoter. Analysis of a panel of myeloma cell lines, primary patient samples and datasets from Oncomine and the Multiple Myeloma Genomics Portal (MMGP) revealed expression of ZKSCAN3 messenger RNA (mRNA) in a majority of samples. Studies of cell lines by western blotting, and of primary tissue microarrays by immunohistochemistry, showed ZKSCAN3 protein expression in a majority, and in a manner that paralleled messenger levels in cell lines. ZKSCAN3 overexpression was associated with increased gene copy number or genomic DNA gain/amplification in a subset based on analysis of data from the MMGP, and from fluorescence in situ hybridization studies of cell lines and primary samples. Overexpression of ZKSCAN3 induced cyclin D2 promoter activity in a MAF/MAFB-independent manner, and to an extent that was influenced by the number of consensus ZKSCAN3 binding sites. Moreover, ZKSCAN3 protein expression correlated with cyclin D2 levels in cell lines and primary samples, and its overexpression induced cyclin D2. Conversely, ZKSCAN3 suppression using small hairpin RNAs (shRNAs) reduced cyclin D2 levels, and, importantly, inhibited myeloma cell line proliferation. Finally, ZKSCAN3 was noted to specifically bind to oligonucleotides representing sequences from the cyclin D2 promoter, and to the endogenous promoter itself in myeloma cells. Taken together, the data support the conclusion that ZKSCAN3 induction represents a mechanism by which myeloma cells can induce cyclin D2 dysregulation, and contribute to disease pathogenesis.