Hong Chang

Clinical Outcomes in t(4;14) Multiple Myeloma: A Chemotherapy-Sensitive Disease Characterized by Rapid Relapse and Alkylating Agent Resistance

PURPOSEnTo determine whether primary drug resistance or rapid relapse explains the poor prognosis seen in t(4;14)-positive multiple myeloma (MM).nnnPATIENTS AND METHODSnA total of 131 patients treated with high-dose therapy (HDT) were assessed, of whom 19 were t(4;14) positive. We examined the presentation features, chemotherapy responsiveness at presentation and to salvage therapies at relapse, and overall survival outcomes.nnnRESULTSnt(4;14)-positive patients had a predominance of the immunoglobulin A isotype (52.6%) but otherwise baseline characteristics were indistinguishable. After treatment with vincristine, doxorubicin, and dexamethasone or dexamethasone alone, 17 (89.7%) of the 19 patients achieved a partial response and 11 patients (57.9%) demonstrated an additional 50% reduction in paraprotein after HDT. Thus, t(4;14)-positive patients are chemotherapy sensitive; however, early progression was common, with 26% of patients progressing before HDT and a median progression-free survival after HDT of only 14.1 months. At relapse, a resistance to alkylating agents was evident, with no responses (zero of 11 patients) seen with conventional-dose alkylating agents. Salvage regimens using thalidomide and/or dexamethasone achieved at least minimal response in 59% of patients. The duration of response was short, however, with a median of only 4.7 months. The median overall survival after HDT was 24.2 months.nnnCONCLUSIONnWe conclude that t(4;14)-positive MM is chemotherapy sensitive but rapid relapse occurs. Resistance to alkylating agents is evident at relapse. The development of novel therapeutic agents is required, including the early clinical study of targeted fibroblast growth factor receptor 3 tyrosine kinase inhibitors, which have shown promise in preclinical studies.

Bone marrow stromal cells protect myeloma cells from bortezomib induced apoptosis by suppressing microRNA-15a expression.

Despite unsurpassed anti-tumor activity of bortezomib for multiple myeloma (MM), drug resistance has emerged as a challenge, especially when MM cells adhere to the stroma. This study aimed to determine whether bone marrow stromal cells (BMSCs) have a role in the development of chemoresistance in MM. Our data demonstrate that the secretion of interleukin-6 (IL-6), vascular endothelial growth factor (VEGF), and cell-to-cell contact with microenvironment-derived stromal cells from patients with multiple myeloma (MM-BMSCs) significantly decreased the sensitivity of myeloma cells to bortezomib treatment. Mechanistically, we found that microRNA (miRNA)- 15a expression was up-regulated in U266 and NCI-H929 cells treated by bortezomib, which was inhibited by MM-BMSCs. miRNA-15a transfected myeloma cells were arrested in G1/S checkpoint and secreted less VEGF compared to control transfected cells, although no significant difference was found in VEGF mRNA levels. In conclusion, our data suggest that via suppressing miRNA-15a expression, BMSCs provide survival support and protect myeloma cells from bortezomib induced apoptosis.

Genetic risk identifies multiple myeloma patients who do not benefit from autologous stem cell transplantation

Summary:Genetic aberrations have emerged as major prognostic factors for patients with multiple myeloma (MM). We evaluated 126 MM patients for t(4;14) or t(11;14), 13q or p53 deletions and correlated the number of genetic aberrations with patients clinical outcome following undergoing autologous stem cell transplantation. We demonstrate the significance of genetic-based risk classification that clearly segregate patients into low (no genetic abnormalities or only t(11;14)), intermediate (any one of the genetic abnormalities other than t(11;14)) and high-risk groups (any two or more of the genetic abnormalities other than t(11;14)). High-risk patients do not benefit from stem cell transplant and should be offered alternative therapies.

1p21 deletions are strongly associated with 1q21 gains and are an independent adverse prognostic factor for the outcome of high-dose chemotherapy in patients with multiple myeloma.

Deletions involving chromosome 1p are frequent events in multiple myeloma (MM). As karyotyping and single nucleotide polymorphism-based mapping analysis identify a minimal common deletion region involving the 1p21 locus, we investigated the prevalence and prognostic significance of del(1p21) in 203 MM patients undergoing high-dose therapy and autologous SCT. 1p21 status was also evaluated in 16 patients with monoclonal gammopathy of undetermined significance (MGUS) and 41 patients with plasma cell leukemia (PCL). FISH combined with cytoplasmic light chain detection (cIg-FISH) detected hemizygous 1p21 deletions in 18% of the MM, 34% of PCL but none of the MGUS cases. The presence of 1p21 deletions was correlated with 1q21(CKS1B) amplification (P=0.01), and del17p(TP53) (P=0.05) but not with del(13q), t(11;14) or t(4;14). Patients with 1p21 deletions had significantly shorter progression-free survival (PFS; median 14.2 vs 25.4 months, P<0.001) and overall survival (OS; median 39.4 vs 82.3 months, P=0.001) than those without such deletions. In multivariate analysis, del(1p21) was an independent risk factor for PFS (P= 0.003) and OS (P=0.013) after adjusting for del(13q), del(p53), t(4;14) and 1q21 amplifications. Our results indicate that del(1p21) is an independent poor prognostic factor associated with disease progression in MM.

Pharmacological activation of the p53 pathway in haematological malignancies.

p53 gene mutations are rarely detected at diagnosis in common haematological cancers such as multiple myeloma (MM), acute myeloid leukaemia (AML), chronic lymphocytic leukaemia (CLL) and Hodgkins disease (HD), although their prevalence may increase with progression to more aggressive or advanced stages. Therapeutic induction of p53 might therefore be particularly suitable for the treatment of haematological malignancies. Some of the anti-tumour activity of current chemotherapeutics has been derived from activation of p53. However, until recently it was unknown whether p53 signalling is functional in certain haematological cancers including MM and if p53 activity is sufficient to trigger an apoptotic response. With the recent discovery of nutlins, which represent the first highly selective small molecule inhibitors of the p53–MDM2 interaction, pharmacological tools are now available to induce p53 irrespective of upstream signalling defects, and to functionally analyse the downstream p53 pathway in primary leukaemia and lymphoma cells. Combination therapy is emerging as a key factor, and development of non-genotoxic combinations seems very promising for tackling the problems of toxicity and resistance. This review will highlight recent findings in the research into molecules capable of modulating p53 protein activities and mechanisms that activate the p53 pathway, restoring response to therapy in haematological malignancies.

Genetic aberrations including chromosome 1 abnormalities and clinical features of plasma cell leukemia.

Plasma cell leukemia (PCL) is a rare form of plasma cell malignancy, few large series reported underlying genetic abnormalities. We systematically evaluated the genomic aberrations in 41 PCL patients by combining fluorescence in situ hybridization with cytoplasmic light chain immunofluorescence and correlated with their clinical outcome. The genomic aberrations in the 15 primary PCL (pPCL) and 26 secondary PCL (sPCL) were compared with 220 newly diagnosed multiple myeloma (MM) patients. There was no significant difference in the prevalence of genetic abnormalities in pPCL and sPCL but del(13q), t(4;14), 1q21 amplification and del(1p21) were more common in PCL than MM. Patients with pPCL had higher creatinine and beta(2)-microglobulin levels and tended to have a longer overall survival than patients with sPCL. In univariant analysis, PCL patients with t(4;14) (p=0.006) and del(1p21) (p=0.003) had shorter overall survivals. In multivariant analysis adjusting for all tested genetic factors as well as clinico-biologically relevant factors including C-reactive protein, calcium and beta(2)-microglobulin, t(4;14) remained a significant predictor for adverse overall survival in PCL (p=0.008).

miR-137 and miR-197 Induce Apoptosis and Suppress Tumorigenicity by Targeting MCL-1 in Multiple Myeloma

Purpose: Deregulation of miRNA has been implicated in the pathogenesis of multiple myeloma. We identified miR-137 and miR-197, mapped to the chromosome 1p (12)–(21) deletion region, and examined their antimyeloma activity as tumor suppressors. Experimental Design: The expression of miR-137/197 was examined in multiple myeloma and normal plasma cells by qRT-PCR. Functional effect of miR-137/197 was analyzed by cell viability, apoptosis, clonogenic, and migration assays. Antimyeloma activity of miR-137/197 was further evaluated in vivo by lentiviral-based or lipid-based delivery in a mouse xenograft model of multiple myeloma. Results: miR-137/197 expression was significantly lower in multiple myeloma cell lines and multiple myeloma patient samples compared with normal plasma cells. Transfection of miR-137/197 resulted in reduction of MCL-1 protein expression, as well as alteration of apoptosis-related genes, and induction of apoptosis, inhibition of viability, colony formation, and migration in multiple myeloma cells. MCL-1 was further validated as a direct target of miR-137/197. Conversely, overexpression of MCL-1 partially reverted the effect of miR-137/197. Importantly, in vivo lentiviral-mediated or intratumor delivery of miR-137/197 induced regression of tumors in murine xenograft models of multiple myeloma. Conclusions: Our study reveals a novel role of miR-137/197 as tumor suppressors in mediating apoptosis in multiple myeloma cells by targeting MCL-1. Our findings provide a proof-of-principle that lentivirus-based or formulated synthetic miR-137/197 exerts therapeutic activity in preclinical models, and support a framework for development of miR-137/197-based treatment strategies in patients with multiple myeloma. Clin Cancer Res; 21(10); 2399–411. ©2015 AACR.

P53 NUCLEAR ACCUMULATION IS ASSOCIATED WITH EXTRAMEDULLARY PROGRESSION OF MULTIPLE MYELOMA

Progression of multiple myeloma (MM) from intramedullary to extramedullary sites heralds an aggressive phase of the disease but to the best of our knowledge, biologic factors have not been studied in paired biopsies from medullary and extramedullary sites. In this study, we immunostained paired bone marrow and extramedullary biopsies from 12 cases of MM for p53, CD56 and MIB-1 (proliferative index). In addition, 22 cases of extramedullary plasmacytoma (EMP) without bone marrow involvement were included as a control group. p53 nuclear accumulations were detected in myeloma cells derived from the extramedullary sites in 9 (75%) of the 12 cases, whereas only 1 of (8%) 12 bone marrow myeloma specimens expressed p53 (P = 0.003). p53 expression was also more prevalent in extramedullary sites of MM than EMP (75% vs. 18%, P = 0.003). There was no significant difference in CD56 expression between intramedullary and extramedullary MM (17% vs. 33%, P = 0.64), or between intramedullary MM and EMP (17% vs. 38%, P = 0.25). The MIB-1 proliferation index increased significantly as plasma cells migrated from the bone marrow microenvironment to extramedullary sites (P = 0.0001). Our data indicates that p53 nuclear expression but not CD56 expression, along with increased proliferation index is associated with disease progression from intramedullary to extramedullary sites in MM.

Suppressing miRNA-15a/-16 expression by interleukin-6 enhances drug-resistance in myeloma cells

The bone marrow microenvironment facilitates the survival, differentiation, and proliferation of myeloma (MM) cells. This study identified that microRNA-15a and -16 expressions tightly correlated with proliferation and drug sensitivity of MM cells. miRNA-15a/-16 expression in MM cells was significantly increased after treatment with cytotoxic agents. The interaction of bone marrow stromal cells (BMSC) with MM cells resulted in decreased miRNA-15a/-16 expression and promoted the survival of the MM cells. Interleukin-6 (IL-6) produced by BMSCs suppressed the expression of miRNA-15a and 16 in a time- and dose- dependent pattern, with the suppression on miRNA-15a being more significant than on miRNA-16. miRNA-15a-transfected MM cells were found to be arrested in G1/S checkpoint, and the transfected MM cells had decreased growth and survival. In conclusion, our data suggest that via suppressing miRNA-15a and -16 expressions, IL-6 secreted by BMSCs promotes drug-resistance in myeloma cells.

t(11;14) multiple myeloma: A subtype associated with distinct immunological features, immunophenotypic characteristics but divergent outcome

UNLABELLEDnt(11;14)(q13;q32) is the most common chromosome translocation in multiple myeloma (MM), but a consensus of clinicopathological features and impact on survival is yet to be reached. We analyzed a cohort of 350 patients with various plasma cell malignancies, including newly diagnosed MM (NDMM, n=253), relapsed/refractory MM (RRMM, n=77), as well as primary and secondary plasma cell leukemia (PCL, n=10 and n=10, respectively).nnnRESULTSnA remarkably higher frequency of t(11;14) was observed in the PCL than in the NDMM. A high incidence of t(11;14) was detected in the IgD, IgM, and nonsecretory MM. The t(11;14) MM group was associated with a significantly higher positive rate of B-lineage associated antigens CD20 and CD79a as well as the lack of CD56 expression. t(11;14) was less likely to be accompanied by 13q14 deletion than 13q14 deletion frequency in non-t(11;14) population (p=0.026), and fewer patients displaying t(11;14) were identified as belonging to the high-risk cytogenetic group due to the extremely low incidence of t(4;14) and t(14;16). As a whole, patients exhibiting t(11;14) had a comparable outcome with the control cohort in NDMM, but CD20 was able to identify two subsets of the disease with dissimilar outcomes. Among patients receiving bortezomib-based treatment, patients harboring t(11;14) without CD20 expression had a significantly shortened PFS (11.0 versus 43.0 months, p=0.005) and OS (16.5 versus 54.0 months, p=0.016) compared with patients displaying t(11;14) with CD20. Our findings suggest that although the t(11;14) plasma cell disorder displayed distinct biological, clinical and laboratory features, it was a heterogeneous disease with divergent outcome.