Faculty Bibliography

Bisphosphonates are recommended in patients with osteolytic lesions secondary to multiple myeloma. We report on the safety of bisphosphonate therapy with long-term follow-up in the Medical Research Council Myeloma IX study. Patients with newly diagnosed multiple myeloma were randomised to zoledronic acid (ZOL; 4 mg intravenously every 21-28 d) or clodronate (CLO; 1600 mg/d orally) plus chemotherapy. Among 1960 patients (5.9-year median follow-up), both bisphosphonates were well tolerated. Acute renal failure events were similar between groups (ZOL 5.2% vs. CLO 5.8% at 2 years; incidence plateaued thereafter). The overall incidence of confirmed osteonecrosis of the jaw (ONJ) was low, but higher with ZOL (ZOL 3.7% vs. CLO 0.5%; P < 0.0001). ONJ events were generally low grade and most occurred between 8 and 30 months (median time to ONJ, 23.7 months). Among 10 patients with ONJ recovery data, four patients in the ZOL group completely recovered, two patients improved, and three patients experienced no improvement; one CLO patient experienced no improvement. Dental surgery or trauma preceded ONJ in six ZOL patients. The incidence of renal adverse events was similar for ZOL and CLO. ONJ incidence remained low and was lower with CLO compared to ZOL. We have seen no further ONJ cases to date.

PURPOSE/OBJECTIVE:To determine the feasibility of whole-body diffusion-weighted (DW) magnetic resonance (MR) imaging for assessment of treatment response in myeloma. MATERIALS AND METHODS/METHODS:This prospective single-institution study was HIPAA-compliant with local research ethics committee approval. Written informed consent was obtained from each subject. Eight healthy volunteers (cohort 1a) and seven myeloma patients (cohort 1b) were imaged twice to assess repeatability of quantitative apparent diffusion coefficient (ADC) estimates. Thirty-four additional myeloma patients (cohort 2) underwent whole-body DW imaging before treatment; 26 completed a posttreatment imaging. Whole-body DW data were compared before and after treatment by using qualitative (ie, observer scores) and quantitative (ie, whole-body segmentation of marrow ADC) methods. Serum paraproteins and/or light chains or bone marrow biopsy defined response. RESULTS:Whole-body DW imaging scores were significantly different between observers (P < .001), but change in scores between observers after treatment was not (P = .49). Sensitivity and specificity for detecting response according to observer scores were 86% (18 of 21 patients) and 80% (4 of 5 patients) for both observers. ADC measurement was repeatable: mean coefficient of variation was 3.8% in healthy volunteers and 2.8% in myeloma patients. Pretreatment ADC in cohort 2 was significantly different from that in cohort 1a (P = .03), but not from that in cohort 1b (P = .2). Mean ADC increased in 95% (19 of 20) of responding patients and decreased in all (five of five) nonresponders (P = .002). A 3.3% increase in ADC helped identify response with 90% sensitivity and 100% specificity; an 8% increase (greater than repeatability of cohort 1b) resulted in 70% sensitivity and 100% specificity. There was a significant negative correlation between change in ADC and change in laboratory markers of response (r = -0.614; P = .001). CONCLUSION/CONCLUSIONS:Preliminary work demonstrates whole-body DW imaging is a repeatable, quantifiable technique for assessment of treatment response in myeloma.

Monoclonal gammopathy of undetermined significance is one of the most common pre-malignant disorders. IgG and IgA monoclonal gammopathy of undetermined significance are precursor conditions of multiple myeloma; light-chain monoclonal gammopathy of undetermined significance of light-chain multiple myeloma; and IgM monoclonal gammopathy of undetermined significance of Waldenström's macroglobulinemia and other lymphoproliferative disorders. Clonal burden, as determined by bone marrow plasma cell percentage or M-protein level, as well as biological characteristics, including heavy chain isotype and light chain production, are helpful in predicting risk of progression of monoclonal gammopathy of undetermined significance to symptomatic disease. Furthermore, alterations in the bone marrow microenvironment of monoclonal gammopathy of undetermined significance patients result in an increased risk of venous and arterial thrombosis, infections, osteoporosis, and bone fractures. In addition, the small clone may occasionally be responsible for severe organ damage through the production of a monoclonal protein that has autoantibody activity or deposits in tissues. These disorders are rare and often require therapy directed at eradication of the underlying plasma cell or lymphoplasmacytic clone. In this review, we provide an overview of the clinical relevance of monoclonal gammopathy of undetermined significance. We also give general recommendations of how to diagnose and manage patients with monoclonal gammopathy of undetermined significance.

Intraclonal heterogeneity was recently described in multiple myeloma (MM), but its full impact on disease progression and relapse has not been entirely explored. The immunoglobulin type produced by myeloma cells provides an excellent marker to follow changes in clonal substructure over time. We have prospectively evaluated serial paraprotein and serum free light chain (FLC) measurements and found that 258 of 520 and 54 of 520 patients who presented with a whole paraprotein relapsed with paraprotein only (PO) and "FLC escape," respectively. The median overall survival of PO patients was longer, when compared with patients whose relapse manifested as an increase in FLC both alone and with a whole paraprotein, as a result of a significantly shorter survival from relapse of the latter groups. These observations fit a model in which 1 clone is able to produce a complete antibody, whereas the other secretes only FLC; the type of relapse represents the outgrowth of different clones, some of which are more resistant to therapy. To our knowledge, this is the largest series describing patients who have relapsed with FLC escape and highlights the importance of monitoring FLC when there is a suspicion of clinical relapse. This study was registered at www.isrctn.org as ISRCTN68454111.

It is clear that cancers comprise a mixture of clones, a feature termed intra-clonal heterogeneity, that compete for spatial and nutritional resources in a fashion that leads to disease progression and therapy resistance. This process of competition resembles the schema proposed by Darwin to explain the origin of the species, and applying these evolutionary biology concepts to cancer has the potential to improve our treatment strategies. Multiple myeloma (MM) has a unique set of characteristics that makes it a perfect model in which to study the presence of intra-clonal heterogeneity and its impact on therapy. Novel therapies have improved the outcome of MM patients, increasing both progression-free and overall survival. Current therapy comprises an induction, consolidation and maintenance phases and it is important to consider how these components of MM therapy are affected by the presence of intra-clonal heterogeneity. In this evolutionary context therapy can be considered as a selective pressure differentially acting on the myeloma clones and impacting on their chances of survival. In this review current knowledge of intra-clonal heterogeneity, as well as its impact on the different components of MM treatment is discussed.

Monoclonal gammopathy of undetermined significance (MGUS) is present in ∼2% of individuals age >50 years. The increased risk of multiple myeloma (MM) in relatives of individuals with MGUS is consistent with MGUS being a marker of inherited genetic susceptibility to MM. Common single-nucleotide polymorphisms (SNPs) at 2p23.3 (rs6746082), 3p22.1 (rs1052501), 3q26.2 (rs10936599), 6p21.33 (rs2285803), 7p15.3 (rs4487645), 17p11.2 (rs4273077), and 22q13.1 (rs877529) have recently been shown to influence MM risk. To examine the impact of these 7 SNPs on MGUS, we analyzed two case-control series totaling 492 cases and 7306 controls. Each SNP independently influenced MGUS risk with statistically significant associations (P < .02) for rs1052501, rs2285803, rs4487645, and rs4273077. SNP associations were independent, with risk increasing with a larger number of risk alleles carried (per allele odds ratio, 1.18; P < 10(-7)). Collectively these data are consistent with a polygenic model of disease susceptibility to MGUS.

Despite recent advances in therapy, subgroups of multiple myeloma continue to have a poor prognosis. Numerous epigenetic changes have been described and occur as both etiologic and secondary events, making myeloma a good disease in which to understand the role of epigenetic therapies. Here, we describe a number of current and potential epigenetic targets in myeloma.

Secondary MYC translocations in myeloma have been shown to be important in the pathogenesis and progression of disease. Here, we have used a DNA capture and massively parallel sequencing approach to identify the partner chromosomes in 104 presentation myeloma samples. 8q24 breakpoints were identified in 21 (20%) samples with partner loci including IGH, IGK and IGL, which juxtapose the immunoglobulin (Ig) enhancers next to MYC in 8/23 samples. The remaining samples had partner loci including XBP1, FAM46C, CCND1 and KRAS, which are important in B-cell maturation or myeloma pathogenesis. Analysis of the region surrounding the breakpoints indicated the presence of superenhancers on the partner chromosomes and gene expression analysis showed increased expression of MYC in these samples. Patients with MYC translocations had a decreased progression-free and overall survival. We postulate that translocation breakpoints near MYC result in colocalization of the gene with superenhancers from loci, which are important in the development of the cell type in which they occur. In the case of myeloma these are the Ig loci and those important for plasma cell development and myeloma pathogenesis, resulting in increased expression of MYC and an aggressive disease phenotype.