Faculty Bibliography

Immunoglobulin production by myeloma plasma cells depends on the unfolded protein response for protein production and folding. Recent studies have highlighted the importance of IRE1alpha and X box binding protein 1 (XBP1), key members of this pathway, in normal B-plasma cell development. We have determined the gene expression levels of IRE1alpha, XBP1, XBP1UNSPLICED (XBP1u), and XBP1SPLICED (XBP1s) in a series of patients with myeloma and correlated findings with clinical outcome. We show that IRE1alpha and XBP1 are highly expressed and that patients with low XBP1s/u ratios have a significantly better overall survival. XBP1s is an independent prognostic marker and can be used with beta2 microglobulin and t(4;14) to identify a group of patients with a poor outcome. Furthermore, we show the beneficial therapeutic effects of thalidomide in patients with low XBP1s/u ratios. This study highlights the importance of XBP1 in myeloma and its significance as an independent prognostic marker and as a predictor of thalidomide response.

Repair of DNA strand breaks induced during lymphoid antigen receptor rearrangement involves non-homologous end-joining (NHEJ). We investigated NHEJ in the aetiology of lymphoproliferative disorders (LPDs) and the disease subtypes therein through real-time quantitative RT-PCR gene expression analysis. Lower expression of XRCC6 and MRE11A was observed in all tumours, with higher expression of both XRCC4 and RAD50 observed only in multiple myeloma (MM). Hierarchical clustering enabled tumours to be clearly distinguished from controls, and by morphological sub-type. We postulate this identifies targets worthy of investigation in the genetic predisposition, pathogenesis and prognosis of lymphoid malignancies.

PURPOSE/OBJECTIVE:Myeloma is a clonal malignancy of plasma cells. Poor-prognosis risk is currently identified by clinical and cytogenetic features. However, these indicators do not capture all prognostic information. Gene expression analysis can be used to identify poor-prognosis patients and this can be improved by combination with information about DNA-level changes. EXPERIMENTAL DESIGN/METHODS:Using single nucleotide polymorphism-based gene mapping in combination with global gene expression analysis, we have identified homozygous deletions in genes and networks that are relevant to myeloma pathogenesis and outcome. RESULTS:We identified 170 genes with homozygous deletions and corresponding loss of expression. Deletion within the "cell death" network was overrepresented and cases with these deletions had impaired overall survival. From further analysis of these events, we have generated an expression-based signature associated with shorter survival in 258 patients and confirmed this signature in data from two independent groups totaling 800 patients. We defined a gene expression signature of 97 cell death genes that reflects prognosis and confirmed this in two independent data sets. CONCLUSIONS:We developed a simple 6-gene expression signature from the 97-gene signature that can be used to identify poor-prognosis myeloma in the clinical environment. This signature could form the basis of future trials aimed at improving the outcome of poor-prognosis myeloma.

This review describes the role that epigenetic changes play in the pathogenesis of cancer, concentrating on the plasma cell malignancy multiple myeloma, and highlights recent findings regarding the efficacy of epigenetic therapeutic agents in laboratory studies and clinical trials. DNA methylation is altered in a wide range of cancers with hypermethylation of CpG islands associated with silencing of tumour suppressor genes. Genes found to be silenced by methylation in myeloma samples include VHL, TP53, CDKN2A, and TGFBR2. Myeloma is linked to the overexpression of a histone methylatransferase (MMSET) and inactivating mutations of a histone demethylase (UTX), suggesting that the regulation of histone methylation is a potential therapeutic target. Abnormal expression of histone deacetylases (HDACs) has been widely described in solid tumours and haematological malignancies. In myeloma, histone deacetylase inhibitors show promising results both in laboratory-based cell culture studies and in clinical trials, where they demonstrate particularly good therapeutic outcome when administered in combination with other standard chemotherapeutic agents. The study of epigenetics shows great promise for understanding the alterations in gene expression that underlie malignancies and provides exciting novel drugable targets.

Myeloma is a malignant proliferation of monoclonal plasma cells. Although morphologically similar, several subtypes of the disease have been identified at the genetic and molecular level. These genetic subtypes are associated with unique clinicopathological features and dissimilar outcome. At the top hierarchical level, myeloma can be divided into hyperdiploid and non-hyperdiploid subtypes. The latter is mainly composed of cases harboring IgH translocations, generally associated with more aggressive clinical features and shorter survival. The three main IgH translocations in myeloma are the t(11;14)(q13;q32), t(4;14)(p16;q32) and t(14;16)(q32;q23). Trisomies and a more indolent form of the disease characterize hyperdiploid myeloma. A number of genetic progression factors have been identified including deletions of chromosomes 13 and 17 and abnormalities of chromosome 1 (1p deletion and 1q amplification). Other key drivers of cell survival and proliferation have also been identified such as nuclear factor- B-activating mutations and other deregulation factors for the cyclin-dependent pathways regulators. Further understanding of the biological subtypes of the disease has come from the application of novel techniques such as gene expression profiling and array-based comparative genomic hybridization. The combination of data arising from these studies and that previously elucidated through other mechanisms allows for most myeloma cases to be classified under one of several genetic subtypes. This paper proposes a framework for the classification of myeloma subtypes and provides recommendations for genetic testing. This group proposes that genetic testing needs to be incorporated into daily clinical practice and also as an essential component of all ongoing and future clinical trials.

In 2005, the first guidelines were published on the management of patients with multiple myeloma (MM). An expert panel reviewed the currently available literature as the basis for a set of revised and updated consensus guidelines for the diagnosis and management of patients with MM who are not eligible for autologous stem cell transplantation. Here we present recommendations on the diagnosis, treatment of newly diagnosed non-transplant-eligible patients and the management of complications occurring during induction therapy among these patients. These guidelines will aid the physician in daily clinical practice and will ensure optimal care for patients with MM.

Empirical antifungal therapy is frequently used in allogeneic transplant patients who have persistent febrile neutropenia and can be associated with high cost, toxicity and breakthrough infections. There are limited reports of strategies for early diagnosis of invasive fungal infection (IFI) and, to our knowledge, no reports of treatment strategies based only on high-resolution computerized tomography (HRCT) scans. We used an early treatment strategy for IFI in 99 consecutive patients undergoing allogeneic transplantation. Patients received caspofungin if they had antibiotic-resistant neutropenic fever for more than 72 h and a positive HRCT scan. Fifty-three of 99 patients (54%) had antibiotic-resistant neutropenic fever at 72 h and would have received parenteral antifungal treatment if an empirical approach had been used. The HRCT-based strategy reduced the use of parenteral antifungal agents to 17/99 patients (17%), a 68% reduction. No subsequent diagnoses of IFI occurred within 100 days in patients with a negative HRCT. Only one patient died from IFI within 100 days. These data suggest that this non-empirical strategy may be feasible and that caspofungin may be effective in this setting. A randomized controlled trial is warranted to further assess these results.

Myeloma cells are highly dependent on the unfolded protein response to assemble folded immunoglobulins correctly. Therefore, targeting protein handling within a myeloma cell by inhibiting the aminopeptidase enzyme system, which catalyses the hydrolysis of amino acids from the proteins NH2 terminus, represents a therapeutic approach. CHR-2797, a novel aminopeptidase inhibitor, is able to inhibit proliferation and induce growth arrest and apoptosis in myeloma cells, including cells resistant to conventional chemotherapeutics. It causes minimal inhibition of bone marrow stromal cell (BMSC) proliferation but is able to overcome the microenvironmental protective effects, inhibiting the proliferation of myeloma cells bound to BMSCs and the increase in vascular endothelial growth factor levels seen when myeloma cells and BMSCs are bound together. Additive and synergistic effects are seen with bortezomib, melphalan, and dexamethasone. Apoptosis occurs via both caspase-dependent and non-caspase-dependent pathways with an increase in Noxa, cleavage of Mcl-1, and activation of the unfolded protein response. Autophagy is also seen. CHR-2797 causes an up-regulation of genes involved in the proteasome/ubiquitin pathway, as well as aminopeptidases, and amino acid deprivation response genes. In conclusion, inhibiting protein turnover using the aminopeptidase inhibitor CHR-2797 results in myeloma cell apoptosis and represents a novel therapeutic approach that warrants further investigation in the clinical setting.

Lenalidomide is an immunomodulatory drug, which has anti-myeloma activity in vitro. Phase II clinical trials have demonstrated lenalidomide in combination with dexamethasone is effective for the treatment of both relapsed refractory myeloma and newly diagnosed patients. Two large phase III studies comparing lenalidomide and dexamethasone to dexamethasone alone in relapsed patients showed superiority in response, progression free and overall survival. It is administered orally for 21 days in a 28 day cycle. Side effects are manageable and include neutropenia and venous thrombotic events. It is currently approved, in combination with dexamethasone, for the treatment of multiple myeloma patients who have received at least one prior therapy. Studies in front line patients and with other drug combinations are ongoing. Given the strength of this data the UK Myeloma Forum believe that lenalidomide in combination with dexamethasone should be available for prescription by UK haematologists according to its licensed indication in patients with relapsed myeloma.