The mutational burden of therapy-related myeloid neoplasms is similar to primary myelodysplastic syndrome but has a distinctive distribution.

Therapy-related myeloid neoplasms (T-MN) are poorly characterized secondary hematological malignancies following chemotherapy/radiotherapy exposure. We compared the clinical and mutational characteristics of T-MN (n = 129) and primary myelodysplastic syndrome (P-MDS, n = 108) patients. Although the somatic mutation frequency was similar between T-MN and P-MDS patients (93% in both groups), the pattern was distinct. TP53 mutations were more frequent in T-MN (29.5 vs. 7%), while spliceosomal complex mutations were more common in P-MDS (56.5 vs. 25.6%). In contrast to P-MDS, the ring sideroblasts (RS) phenotype was not associated with better survival in T-MN, most probably due to genetic association with TP53 mutations. SF3B1 was mutated in 96% of P-MDS with ≥15% RS, but in only 32% T-MN. TP53 mutations were detected in 92% T-MN with ≥15% RS and SF3B1 wild-type cases. Interestingly, T-MN and P-MDS patients with "Very low" or "Low" Revised International Prognostic Scoring System (IPSS-R) showed similar biological and clinical characteristics. In a Cox regression analysis, TP53 mutation was a poor prognostic factor in T-MN, independent of IPSS-R cytogenetics, disease-modifying therapy, and NRAS mutation. Our data have direct implications for T-MN management and provide evidence that, in addition to conventional disease parameters, mutational analysis should be incorporated in T-MN risk stratification.

Subclonal evolution in disease progression from MGUS/SMM to multiple myeloma is characterised by clonal stability.

Multiple myeloma (MM) is a largely incurable haematological malignancy defined by the clonal proliferation of malignant plasma cells (PCs) within the bone marrow. Clonal heterogeneity has recently been established as a feature in MM, however, the subclonal evolution associated with disease progression has not been described. Here, we performed whole-exome sequencing of serial samples from 10 patients, providing new insights into the progression from monoclonal gammopathy of undetermined significance (MGUS) and smouldering MM (SMM), to symptomatic MM. We confirm that intraclonal genetic heterogeneity is a common feature at diagnosis and that the driving events involved in disease progression are more subtle than previously reported. We reveal that MM evolution is mainly characterised by the phenomenon of clonal stability, where the transformed subclonal PC populations identified at MM are already present in the asymptomatic MGUS/SMM stages. Our findings highlight the possibility that PC extrinsic factors may play a role in subclonal evolution and MGUS/SMM to MM progression.

A cohort study assessing the impact of small volume blood tubes on diagnostic test quality and iatrogenic blood loss in a cohort of adult haematology patients.

BACKGROUND/AIM: To estimate the reduction in blood volume loss and impact on diagnostic test quality associated with introduction of small volume blood tubes in a cohort of haematology inpatients compared to a historical comparator group. METHODS: Prospective cohort study of haematology inpatients admitted to a tertiary referral hospital in Adelaide. Small volume blood tubes were used in an intervention cohort admitted between 2012 and 2013 and compared to a control cohort admitted between 2009 and 2010 where standard volume blood tubes had been used. The diagnostic test quality, specimen integrity and total reduction in blood loss associated with small volume blood tubes were estimated. RESULTS: Small volume blood tubes demonstrated acceptable collinearity on commonly assayed haematological and biochemical parameters. Small volume tubes were associated with a 42% reduction in blood volume loss equating to a saving of 8.5 mL per patient per day or 180 mL of blood loss over a 3-week admission. Small volume blood tubes were associated with a slight but significantly increased rate of fibrin contamination of ethylenediaminetetraacetic acid samples (0.2-0.5% of specimens). CONCLUSION: Small volume blood tubes are associated with a substantial reduction in total blood volume collected per day in haematology inpatients. They have similar diagnostic validity and sample integrity to that of standard volume containers.

The effect of the PI3K inhibitor BKM120 on tumour growth and osteolytic bone disease in multiple myeloma.

The plasma cell malignancy multiple myeloma (MM) is unique amongst haematological malignancies in its capacity to cause osteoclast-mediated skeletal destruction. The PI3K/Akt pathway mediates proliferation, survival and drug resistance in MM plasma cells and is also involved in regulating the formation and activity of bone-forming osteoblasts and bone-resorbing osteoclasts. NVP-BKM120 (Buparlisib, Novartis) is a PI3K inhibitor that is currently undergoing clinical evaluation in several tumour settings. In this study, we have examined the anti-tumorigenic effects of BKM120 in an immunocompetent mouse model of MM and its effects on osteoblast and osteoclast formation and function. BKM120 treatment (40 mg/kg) resulted in a significant decrease in serum paraprotein and tumour burden, and µCT analysis of the proximal tibia revealed a significant reduction in the number of osteolytic bone lesions in BKM120-treated animals. BKM120 also mediated a significant increase in serum levels of the osteoblast marker P1NP, and a significant decrease in serum levels of the osteoclast marker TRAcP5. In vitro, BKM120 decreased MM plasma cell proliferation, osteoclast formation and function, and promoted osteoblast formation and function. These findings suggest that, in addition to its anti-tumour properties, BKM120 could be used to treat osteolytic bone disease in MM patients.

The effect of the dual PI3K and mTOR inhibitor BEZ235 on tumour growth and osteolytic bone disease in multiple myeloma.

The plasma cell malignancy multiple myeloma (MM) is unique among haematological malignancies in its capacity to cause osteoclast-mediated skeletal destruction. The PI3K/Akt/mTOR pathway mediates proliferation, survival and drug resistance in MM plasma cells and is also involved in regulating the formation and activity of bone-forming osteoblasts and bone-resorbing osteoclasts. NVP-BEZ235 is a dual pan class I PI3K and mTOR inhibitor that is currently undergoing clinical evaluation in several tumour settings. In this study, we examined the anti-tumorigenic effects of BEZ235 in an immunocompetent mouse model of MM and assessed the effects of BEZ235 on osteoblast and osteoclast formation and function. BEZ235 treatment (50 mg/kg) resulted in a significant decrease in serum paraprotein and tumour burden, and µCT analysis of the proximal tibia revealed a significant reduction in the number of osteolytic bone lesions in BEZ235-treated animals. Levels of the serum osteoblast marker P1NP were significantly higher in BEZ235-treated animals, while levels of the osteoclast marker TRAcP5 were reduced. In vitro, BEZ235 decreased MM plasma cell proliferation, osteoclast formation and function and promoted osteoblast formation and function. These findings suggest that, in addition to its anti-tumour properties, BEZ235 could be useful in treating osteolytic bone disease in MM patients.

SAMSN1 is a tumor suppressor gene in multiple myeloma.

Multiple myeloma (MM), a hematological malignancy characterized by the clonal growth of malignant plasma cells (PCs) in the bone marrow, is preceded by the benign asymptomatic condition, monoclonal gammopathy of undetermined significance (MGUS). Several genetic abnormalities have been identified as critical for the development of MM; however, a number of these abnormalities are also found in patients with MGUS, indicating that there are other, as yet unidentified, factors that contribute to the onset of MM disease. In this study, we identify a Samsn1 gene deletion in the 5TGM1/C57BL/KaLwRij murine model of myeloma. In addition, SAMSN1 expression is reduced in the malignant CD138+ PCs of patients with MM and this reduced expression correlates to total PC burden. We identify promoter methylation as a potential mechanism through which SAMSN1 expression is modulated in human myeloma cell lines. Notably, re-expression of Samsn1 in the 5TGM1 murine PC line resulted in complete inhibition of MM disease development in vivo and decreased proliferation in stromal cell-PC co-cultures in vitro. This is the first study to identify deletion of a key gene in the C57BL/KaLwRij mice that also displays reduced gene expression in patients with MM and is therefore likely to play an integral role in MM disease development.

Interleukin-3-mediated regulation of ß-catenin in myeloid transformation and acute myeloid leukemia.

Aberrant activation of ß-catenin is a common event in AML and is an independent predictor of poor prognosis. Although increased ß-catenin signaling in AML has been associated with oncogenic translocation products and activating mutations in the FLT3R, the mechanisms that activate ß-catenin in AML more broadly are still unclear. Here, we describe a novel link between IL-3 signaling and the regulation of ß-catenin in myeloid transformation and AML. In a murine model of HoxB8 and IL-3 cooperation, we show that ß-catenin protein levels are modulated by IL-3 and that Cre-induced deletion of ß-catenin abolishes IL-3-dependent growth and colony formation. In IL-3-dependent leukemic TF-1.8 cells, we observed increased ß-catenin protein levels and nuclear localization in response to IL-3, and this correlated with transcriptional induction of ß-catenin target genes. Furthermore, IL-3 promoted ß-catenin accumulation in a subset of AML patient samples, and gene-expression profiling of these cells revealed induction of WNT/ß-catenin and TCF4 gene signatures in an IL-3-dependent manner. This study is the first to link ß-catenin activation to IL-3 and suggests that targeting IL-3 signaling may be an effective approach for the inhibition of ß-catenin activity in some patients with AML.

Myeloma plasma cells alter the bone marrow microenvironment by stimulating the proliferation of mesenchymal stromal cells.

Multiple myeloma is an incurable hematologic cancer characterized by the clonal proliferation of malignant plasma cells within the bone marrow. Numerous studies suggest that the myeloma plasma cells occupy and alter the stromal tissue of the bone marrow as a means of enhancing their survival and growth. However, the nature and magnitude of the changes to the stromal cell tissue remain to be determined. In this study, we used mesenchymal stromal cell and osteoblast-related cell surface marker expression (STRO-1 and alkaline phosphatase, respectively) and flow cytometry to enumerate mesenchymal stromal cell and osteoblast numbers in bone marrow recovered from myeloma patients at the time of diagnosis. Using this approach, we identified an increase in the number of STRO-1 positive colony forming mesenchymal stromal cells and a concomitant decrease in alkaline phophatase osteoblasts. Notably, this increase in mesenchymal stromal cell numbers correlated closely with plasma cell burden at the time of diagnosis. In addition, in comparison with the osteoblast population, the STRO-1+ mesenchymal stromal cell population was found to express higher levels of plasma cell- and osteoclast-activating factors, including RANKL and IL-6, providing a mechanism by which an increase in mesenchymal stromal cells may promote and aid the progression of myeloma. Importantly, these findings were faithfully replicated in the C57BL/KaLwRij murine model of myeloma, suggesting that this model may present a unique and clinically relevant system in which to identify and therapeutically modulate the bone microenvironment and, in turn, alter the progression of myeloma disease.

Circulating N-cadherin levels are a negative prognostic indicator in patients with multiple myeloma.

N-cadherin (cadherin 2, type 1, N-cadherin (neuronal); CDN2) is a homotypic adhesion molecule that is upregulated in breast, prostate and bladder cancer. Here we investigated the prognostic significance of upregulated N-cadherin expression in multiple myeloma (MM). Our results indicate that N-cadherin protein and gene expression is abnormally increased in trephine biopsies and CD38(++) /CD138(+) plasma cells from MM patients, when compared with those of normal donors. In addition, levels of circulating N-cadherin were elevated in a subset of patients with MM (n = 81; mean: 14·50 ng/ml, range: 0-146·78 ng/ml), relative to age-matched controls (n = 27; mean: 2·66 ng/ml, range: 0-5·96 ng/ml), although this did not reach statistical significance. Notably, patients with abnormally high levels of N-cadherin (>6 ng/ml) had decreased progression-free survival (P = 0·036; hazard ratio: 1·94) and overall survival (P = 0·002; hazard ratio: 3·15), when compared with patients with normal N-cadherin levels (≤6 ng/ml). Furthermore, multivariate analyses revealed that the combination of N-cadherin levels and International Staging System (ISS) was a more powerful prognostic indicator than using ISS alone. Collectively, our studies demonstrate that circulating N-cadherin levels are a viable prognostic marker for high-risk MM patients.

Assessment of whole body MRI and sestamibi technetium-99m bone marrow scan in prediction of multiple myeloma disease progression and outcome: a prospective comparative study.

OBJECTIVES: This study aims primarily to determine whether whole body MRI (WB-MRI) and Sestamibi Technetium-99m-bone marrow (MIBI) scans in the same patients produce the same estimate of disease load and location, and secondly, to study possible association between the bone disease detected by these scans and the effect on disease outcome and survival. Bone disease occurs in about 90% of multiple myeloma (MM) patients. There are no data comparing the new diagnostic modalities with WB-MRI and MIBI in MM. DESIGN: A prospective comparative study between WB-MRI and MIBI scans in assessing bone disease and outcome of MM. PARTICIPANTS AND METHODS: Sixty-two consecutive patients with confirmed MM underwent simultaneous WB-MRI (both axial T1 and turbo spin echo short tau inversion recovery (STIR)) and MIBI scans at a single institution from January 2010 to January 2011, and their survival status was determined in January 2012. The median age was 62 years (range 37-88) with a male-to-female ratio of 33 : 29. RESULTS: In vertebrae and long bones, MRI scan detected more disease compared with MIBI scan (p<0.001) but there was less difference in the skull (p=0.09). In the ribcage, the MIBI scan detected more lytic lesions of the ribs compared with MRI scan (p<0.001). Thirteen of the 62 patients died during the 24-month follow-up. Increased disease detected in all bones by both scans was associated with increased mortality risk (MIBI p=0.001; MRI-STIR p=0.044; but not MRI-T1 p=0.44). In all combined bone groups, the mean MIBI scan results provided a better prediction of mortality than MRI scan over the follow-up period (MRI-T1 vs MIBI p=0.019; MRI-STIR vs MIBI p=0.047). CONCLUSIONS: Although WB-MRI detected more MM bone disease, MIBI scan predicted overall disease outcome and mortality better than MRI scan. Further studies to define optimum use of these imaging techniques are warranted. TRIAL REGISTRATION NUMBER: The study was registered prospectively in the Australian and New Zealand Clinical Trials Registry at http://www.ANZCTR.org.au under No: ACTRN12609000761268.