Weekly carfilzomib plus cyclophosphamide and dexamethasone in the treatment of relapsed/refractory multiple myeloma: Final results from the MCRN-003/MYX.1 single arm phase II trial

The MCRN-003/CCTGMYX.1 is a single arm phase II trial of weekly carfilzomib, cyclophosphamide and dexamethasone (wKCd), exploring a convenient immunomodulator (IMiD)-free regimen in relapsed myeloma. Weekly carfilzomib (20/70 mg/m² ), dexamethasone 40 mg and cyclophosphamide 300 mg/m² was delivered over 28-day cycles. The primary endpoint was overall response after four cycles. Secondary endpoints included toxicity, response depth, PFS and OS. Exploratory endpoints included the impact of cytogenetics, prior therapy exposure and serum free light chain (sFLC) escape; 76 patients were accrued. The ORR was 85% (68% ≥very good partial response [VGPR] and 29% ≥complete response [CR]). The median OS and PFS were 27 and 17 months respectively. High-risk cytogenetics conferred a worse ORR (75% vs. 97%, p = .013) and median OS (18 months vs. NR, p = .002) with a trend toward a worse median PFS (14 vs. 22 months, p = .06). Prior proteasome inhibitor (PI) or lenalidomide did not influence OS or PFS. The sFLC was noted in 15% of patients with a median PFS of 17 months when included as a progression event. The most common ≥ grade 3 non-hematologic adverse events were infectious (40%), vascular (17%) and cardiac (15%). The wKCD is a safe and effective regimen in relapse, especially for patients ineligible for lenalidomide-based therapies.

MS4A4A: a novel cell surface marker for M2 macrophages and plasma cells

MS4A4A is a member of the membrane-spanning, four domain family, subfamily A (MS4A) that includes CD20 (MS4A1), FcRβ (MS4A2) and Htm4 (MS4A3). Like the first three members of this family, transcription of MS4A4A appears to be limited to hematopoietic cells. To evaluate expression of the MS4A4A protein in hematopoietic cell lineages and subsets we generated monoclonal antibodies against extracellular epitopes for use in flow cytometry. In human peripheral blood we found that MS4A4A is expressed at the plasma membrane in monocytes but not in granulocytes or lymphocytes. In vitro differentiation of monocytes demonstrated that MS4A4A is expressed in immature but not activated dendritic cells, and in macrophages generated in the presence of interleukin-4 ('alternatively activated' or M2 macrophages) but not by interferon-γ and lipopolysaccharide ('classically' activated or M1 macrophages). MS4A4A was expressed in the U937 monocytic cell line only after differentiation. In normal bone marrow, MS4A4A was expressed in mature monocytes but was undetected, or detected at only a low level, in myeloid/monocytic precursors, as well as their malignant counterparts in patients with various subtypes of myeloid leukemia. Although MS4A4A was not expressed in healthy B lymphocytes, it was highly expressed in normal plasma cells, CD138+ cells from multiple myeloma patients, and bone marrow B cells from a patient with mantle cell lymphoma. These findings suggest immunotherapeutic potential for MS4A4A antibodies in targeting alternatively activated macrophages such as tumor-associated macrophages, and in the treatment of multiple myeloma and mantle cell lymphoma.

FGFR3 preferentially colocalizes with IGH in the interphase nucleus of multiple myeloma patient B-cells when FGFR3 is located outside of CT4

Many B-cell malignancies are characterized by chromosomal translocations involving IGH and a proto-oncogene. For translocations to occur, spatial proximity of translocation-prone genes is necessary. Currently, it is not known how such genes are brought into proximity with one another. Although decondensed chromosomes occupy definitive, non-random spaces in the interphase nucleus known as chromosome territories (CTs), chromatin at the edges of CTs can intermingle, and specific genomic regions from some chromosomes have been shown to "loop out" of their respective CTs. This extra-territorial positioning of specific genomic regions may provide a mechanism whereby translocation-prone genes are brought together in the interphase nucleus. FGFR3 and MAF recurrently participate in translocations with IGH at different frequencies. Using 3D, 4-color FISH, and 3D analysis software, we show frequent extra-territorial positioning of FGFR3 and significantly less frequent extra-territorial positioning of MAF. Frequent extra-territorial positioning may be characteristic of FGFR3 in B-cells from healthy adult donors and non-malignant B-cells from patients, but not in hematopoietic stem cells from patients with translocations. The frequency of extra-territorial positioning of FGFR3 and MAF in B-cells correlates with the frequency of translocations in the patient population. Most importantly, in patient B-cells, we demonstrate a significant proportion of extra-territorial FGFR3 participating in close loci pairs and/or colocalizing with IGH. This preliminary work suggests that in patient B-cells, extra-territorial positioning of FGFR3 may provide a mechanism for forming close loci pairs and/or colocalization with IGH; indirectly facilitating translocation events involving these two genes. © 2016 Wiley Periodicals, Inc.

Cost-effectiveness of lenalidomide plus dexamethasone vs. bortezomib plus melphalan and prednisone in transplant-ineligible U.S. patients with newly-diagnosed multiple myeloma

OBJECTIVE

To conduct a cost-effectiveness assessment of lenalidomide plus dexamethasone (Rd) vs bortezomib plus melphalan and prednisone (VMP) as initial treatment for transplant-ineligible patients with newly-diagnosed multiple myeloma (MM), from a U.S. payer perspective.

METHODS

A partitioned survival model was developed to estimate expected life-years (LYs), quality-adjusted LYs (QALYs), direct costs and incremental costs per QALY and LY gained associated with use of Rd vs VMP over a patient's lifetime. Information on the efficacy and safety of Rd and VMP was based on data from multinational phase III clinical trials and a network meta-analysis. Pre-progression direct costs included the costs of Rd and VMP, treatment of adverse events (including prophylaxis) and routine care and monitoring associated with MM. Post-progression direct costs included costs of subsequent treatment(s) and routine care and monitoring for progressive disease, all obtained from published literature and estimated from a U.S. payer perspective. Utilities were obtained from the aforementioned trials. Costs and outcomes were discounted at 3% annually.

RESULTS

Relative to VMP, use of Rd was expected to result in an additional 2.22 LYs and 1.47 QALYs (discounted). Patients initiated with Rd were expected to incur an additional $78,977 in mean lifetime direct costs (discounted) vs those initiated with VMP. The incremental costs per QALY and per LY gained with Rd vs VMP were $53,826 and $35,552, respectively. In sensitivity analyses, results were found to be most sensitive to differences in survival associated with Rd vs VMP, the cost of lenalidomide and the discount rate applied to effectiveness outcomes.

CONCLUSIONS

Rd was expected to result in greater LYs and QALYs compared with VMP, with similar overall costs per LY for each regimen. Results of this analysis indicated that Rd may be a cost-effective alternative to VMP as initial treatment for transplant-ineligible patients with MM, with an incremental cost-effectiveness ratio well within the levels for recent advancements in oncology.

Single-Cell Analysis and Next-Generation Immuno-Sequencing Show That Multiple Clones Persist in Patients with Chronic Lymphocytic Leukemia

The immunoglobulin heavy chain (IGH) gene rearrangement in chronic lymphocytic leukemia (CLL) provides a unique molecular signature; however, we demonstrate that 26/198 CLL patients (13%) had more than one IGH rearrangement, indicating the power of molecular technology over phenotypic analysis. Single-cell PCR analysis and next-generation immuno-sequencing identified IGH-defined clones. In 23% (18/79) of cases whose clones carried unmutated immunoglobulin heavy chain variable (IGHV) genes (U-CLL), IGH rearrangements were bialleic with one productive (P) and one non-productive (NP) allele. Two U-CLL were biclonal, each clone being monoallelic (P). In 119 IGHV-mutated (M-CLL) cases, one had biallelic rearrangements in their CLL (P/NP) and five had 2–4 distinct clones. Allelic exclusion was maintained in all B-clones analyzed. Based on single-cell PCR analysis, 5/11 partner clones (45%) reached levels of >5x10⁹ cells/L, suggesting second CLL clones. Partner clones persisted over years. Conventional IGH characterization and next-generation sequencing of 13 CLL, 3 multiple myeloma, 2 Waldenstrom’s macroglobulinemia and 3 age-matched healthy donors consistently identified the same rearranged IGH sequences. Most multiple clones occurred in M-CLL, perhaps indicative of weak clonal dominance, thereby associating with a good prognosis. In contrast, biallelic CLL occurred primarily in U-CLL thus being associated with poor prognosis. Extending beyond intra-clonal diversity, molecular analysis of clonal evolution and apparent subclones in CLL may also reflect inter-clonal diversity.

Skeletal muscle radio-density is an independent predictor of response and outcomes in follicular lymphoma treated with chemoimmunotherapy

Skeletal muscle radio-density (SMD) measures muscle radiation attenuation (in Hounsfield Units, HU) on computed tomography (CT) scans. Low SMD is prognostic of poor survival in melanoma, however its significance is unknown for hematologic malignancies. We performed a single institution, retrospective review of all follicular lymphoma (FL) patients who received chemoimmunotherapy from 2004-2009. Patient demographics, FL International Prognostic Index 1 (FLIPI-1), progression free (PFS) and overall survival (OS) were collected as primary endpoints. Objective response rates (ORR) were secondary. SMD was calculated using pre-treatment CT scans. In 145 patients reviewed, median values were age 59, FLIPI-1 of 2, stage III, and 8 chemoimmunotherapy cycles received. Median PFS for those with low SMD (<36.6 and <33.1 HU for patients with BMI ≤ 25 and > 25 kg/m2, respectively) compared to those with high SMD was profoundly worse, 69.6 vs. 106.7 months (hazard ratio [HR] 1.85; p = 0.01), respectively. Median OS was not reached in patients with high SMD vs. 92.7 months in low SMD patients (HR 4.02; p = 0.0002). Multivariate analysis supported lower SMD's OS detriment (HR = 3.40; p = 0.002) independent of FLIPI-1 (HR 1.46-2.76, p = 0.05) or gender. Low SMD predicted lower ORR, 83 vs. 96% (p = 0.01). SMD predicts survival independent of FLIPI-1 and potentially chemoimmunotherapy response. SMD is an inexpensive and powerful tool that can complement FLIPI-1.

Aberrant posttranscriptional processing of hyaluronan synthase 1 in malignant transformation and tumor progression

It is becoming increasingly apparent that splicing defects play a key role in cancer, and that alterations in genomic splicing elements promote aberrant splicing. Alternative splicing increases the diversity of the human transcriptome and increases the numbers of functional gene products. However, dysregulation that leads to aberrant pre-mRNA splicing can contribute to cancer. Hyaluronan (HA), known to be an important component of cancer progression, is synthesized by hyaluronan synthases (HASs). In cancer cells, hyaluronan synthase 1 (HAS1) pre-mRNA is abnormally spliced to generate a family of aberrant splice variants (HAS1Vs) that synthesize extracellular and intracellular HA. HAS1Vs are clinically relevant, being found almost exclusively in malignant cells. Expression of aberrant HAS1Vs predicts poor survival in multiple myeloma. In this review, we summarize the unusual properties of HAS1Vs and their relationship to cancer. HAS1Vs form heterogeneous multimers with normally spliced HAS1 as well as with each other and with HAS3. Aberrant variants of HAS1 synthesize HA. Extracellular HA synthesized by HAS1Vs is likely to promote malignant spread. We speculate that synthesis of intracellular HA plays a fundamental and early role in oncogenesis by promoting genetic instability and the emergence of viable cancer variants that lead to aggressive disease.

Lenalidomide and dexamethasone in transplant-ineligible patients with myeloma

BACKGROUND

The combination melphalan-prednisone-thalidomide (MPT) is considered a standard therapy for patients with myeloma who are ineligible for stem-cell transplantation. However, emerging data on the use of lenalidomide and low-dose dexamethasone warrant a prospective comparison of the two approaches.

METHODS

We randomly assigned 1623 patients to lenalidomide and dexamethasone in 28-day cycles until disease progression (535 patients), to the same combination for 72 weeks (18 cycles; 541 patients), or to MPT for 72 weeks (547 patients). The primary end point was progression-free survival with continuous lenalidomide-dexamethasone versus MPT.

RESULTS

The median progression-free survival was 25.5 months with continuous lenalidomide-dexamethasone, 20.7 months with 18 cycles of lenalidomide-dexamethasone, and 21.2 months with MPT (hazard ratio for the risk of progression or death, 0.72 for continuous lenalidomide-dexamethasone vs. MPT and 0.70 for continuous lenalidomide-dexamethasone vs. 18 cycles of lenalidomide-dexamethasone; P<0.001 for both comparisons). Continuous lenalidomide-dexamethasone was superior to MPT for all secondary efficacy end points, including overall survival (at the interim analysis). Overall survival at 4 years was 59% with continuous lenalidomide-dexamethasone, 56% with 18 cycles of lenalidomide-dexamethasone, and 51% with MPT. Grade 3 or 4 adverse events were somewhat less frequent with continuous lenalidomide-dexamethasone than with MPT (70% vs. 78%). As compared with MPT, continuous lenalidomide-dexamethasone was associated with fewer hematologic and neurologic toxic events, a moderate increase in infections, and fewer second primary hematologic cancers.

CONCLUSIONS

As compared with MPT, continuous lenalidomide-dexamethasone given until disease progression was associated with a significant improvement in progression-free survival, with an overall survival benefit at the interim analysis, among patients with newly diagnosed multiple myeloma who were ineligible for stem-cell transplantation. (Funded by Intergroupe, Francophone du Myélome and Celgene; FIRST ClinicalTrials.gov number, NCT00689936; European Union Drug Regulating Authorities Clinical Trials number, 2007-004823-39.).

Active idiotypic vaccination versus control immunotherapy for follicular lymphoma

PURPOSE

Idiotypes (Ids), the unique portions of tumor immunoglobulins, can serve as targets for passive and active immunotherapies for lymphoma. We performed a multicenter, randomized trial comparing a specific vaccine (MyVax), comprising Id chemically coupled to keyhole limpet hemocyanin (KLH) plus granulocyte macrophage colony-stimulating factor (GM-CSF) to a control immunotherapy with KLH plus GM-CSF.

PATIENTS AND METHODS

Patients with previously untreated advanced-stage follicular lymphoma (FL) received eight cycles of chemotherapy with cyclophosphamide, vincristine, and prednisone. Those achieving sustained partial or complete remission (n=287 [44%]) were randomly assigned at a ratio of 2:1 to receive one injection per month for 7 months of MyVax or control immunotherapy. Anti-Id antibody responses (humoral immune responses [IRs]) were measured before each immunization. The primary end point was progression-free survival (PFS). Secondary end points included IR and time to subsequent antilymphoma therapy.

RESULTS

At a median follow-up of 58 months, no significant difference was observed in either PFS or time to next therapy between the two arms. In the MyVax group (n=195), anti-Id IRs were observed in 41% of patients, with a median PFS of 40 months, significantly exceeding the median PFS observed in patients without such Id-induced IRs and in those receiving control immunotherapy.

CONCLUSION

This trial failed to demonstrate clinical benefit of specific immunotherapy. The subset of vaccinated patients mounting specific anti-Id responses had superior outcomes. Whether this reflects a therapeutic benefit or is a marker for more favorable underlying prognosis requires further study.

A three-dimensional tissue culture model to study primary human bone marrow and its malignancies

Tissue culture has been an invaluable tool to study many aspects of cell function, from normal development to disease. Conventional cell culture methods rely on the ability of cells either to attach to a solid substratum of a tissue culture dish or to grow in suspension in liquid medium. Multiple immortal cell lines have been created and grown using such approaches, however, these methods frequently fail when primary cells need to be grown ex vivo. Such failure has been attributed to the absence of the appropriate extracellular matrix components of the tissue microenvironment from the standard systems where tissue culture plastic is used as a surface for cell growth. Extracellular matrix is an integral component of the tissue microenvironment and its presence is crucial for the maintenance of physiological functions such as cell polarization, survival, and proliferation. Here we present a 3-dimensional tissue culture method where primary bone marrow cells are grown in extracellular matrix formulated to recapitulate the microenvironment of the human bone (rBM system). Embedded in the extracellular matrix, cells are supplied with nutrients through the medium supplemented with human plasma, thus providing a comprehensive system where cell survival and proliferation can be sustained for up to 30 days while maintaining the cellular composition of the primary tissue. Using the rBM system we have successfully grown primary bone marrow cells from normal donors and patients with amyloidosis, and various hematological malignancies. The rBM system allows for direct, in-matrix real time visualization of the cell behavior and evaluation of preclinical efficacy of novel therapeutics. Moreover, cells can be isolated from the rBM and subsequently used for in vivo transplantation, cell sorting, flow cytometry, and nucleic acid and protein analysis. Taken together, the rBM method provides a reliable system for the growth of primary bone marrow cells under physiological conditions.

Aberrant splicing, hyaluronan synthases and intracellular hyaluronan as drivers of oncogenesis and potential drug targets

Current evidence suggests a significant role of aberrant splicing in the development and maintenance of malignancy. This multistep, tightly regulated epigenetic process leads to the production of abnormal proteins with abnormal functions contributing to underlying mechanisms of malignant transformation. Splicing patterns in malignant cells can be altered not only by the mutations detected on the aberrantly spliced gene, but also by the mutations detected on the genes encoding splicing factors. For example, aberrant pre-mRNA splicing, leading to intracellular or extracellular HA synthesis by HASs, contributes to the initiation and progression of various types of cancer. The influence of intracellular HA appears to be particularly significant and is promoted by aberrant splicing. In this review we report a model describing oncogenic potential of aberrant splicing, with a focus on HAS1 and intracellular HA. We also suggest that the influence of splicing mutations on malignant disease is likely multifactorial. For the triple axis of HA, HAS1 and RHAMM, mutations in HAS1 provide an indicator that these aberrations contribute to the events that lead to malignancy through increased risk and predisposition. Here, we also summarize the impact of splicing abnormalities on cancer and the possible oncogenic impact of aberrantly spliced HAS1. In conclusion, we emphasize that specific gene splice variants and the splicing process itself offer potential targets for novel drug treatment strategies.

The systemic cytokine environment is permanently altered in multiple myeloma

Multiple myeloma (MM) is an incurable bone marrow malignancy of the B cell lineage. Utilizing multiplex Luminex technology we measured levels of 25 cytokines in the plasma of normal donors (n = 177), those with monoclonal gammopathy of undetermined significance (n = 8), and MM patients (n = 55) with either active disease, on treatment, or in remission. The cytokine levels were compared between normal donors and MM patients as well as between various phases of MM, and discriminant analysis was used to create a predictive classification model based on the differentially expressed cytokines. Evaluating age- and gender-dependence of cytokine expression, we determined that with age there is a shift toward a pro-inflammatory environment. Moreover, we observed a strong gender bias in cytokine expression. However, the profile of differentially expressed cytokines was heavily skewed toward an anti-inflammatory, pro-tumorigenic response in patients with MM. Significantly, our predictive model placed all patients in remission in the same category as those with active disease. Thus, our study demonstrates that the homeostasis of systemic cytokines is not restored when MM patients enter remission, suggesting that once an individual has cancer, the microenvironment is permanently altered and the system is primed for a relapse.

Differential nuclear organization of translocation-prone genes in nonmalignant B cells from patients with t(14;16) as compared with t(4;14) or t(11;14) myeloma

Gene organization in nonmalignant B cells from t(4;14) and t(11;14) multiple myeloma (MM) patients differs from that of healthy donors. Among recurrent IGH translocations in MM, the frequency of t(4;14) (IGH and FGFR3) or t(11;14) (IGH and CCND1) is greater than the frequency of t(14;16) (IGH and MAF). Gene organization in t(14;16) patients may influence translocation potential of MAF with IGH. In patients, three-dimensional FISH revealed the positions of IGH, CCND1, FGFR3, and MAF in nonmalignant B cells that are likely similar to those when MM first arose, compared with B cells from healthy donors. Overall, IGH occupies a more central nuclear position while MAF is more peripherally located. However, for B cells from t(4;14) and t(11;14) patients, IGH and FGFR3, or IGH and CCND1 are found in spatial proximity: IGH and MAF are not. This differs in B cells from t(14;16) patients and healthy donors where IGH is approximately equidistant to FGFR3, CCND1, and MAF, suggesting that gene organization in t(14;16) patients is different from that in t(4;14) or t(11;14) patients. Translocations between IGH and MAF may arise only in the absence of close proximity to the more frequent partners, as appears to be the case for individuals who develop t(14;16) MM.

Alteration of introns in a hyaluronan synthase 1 (HAS1) minigene convert Pre-mRNA [corrected] splicing to the aberrant pattern in multiple myeloma (MM): MM patients harbor similar changes

Aberrant pre-mRNA splice variants of hyaluronan synthase 1 (HAS1) have been identified in malignant cells from cancer patients. Bioinformatic analysis suggests that intronic sequence changes can underlie aberrant splicing. Deletions and mutations were introduced into HAS1 minigene constructs to identify regions that can influence aberrant intronic splicing, comparing the splicing pattern in transfectants with that in multiple myeloma (MM) patients. Introduced genetic variations in introns 3 and 4 of HAS1 as shown here can promote aberrant splicing of the type detected in malignant cells from MM patients. HAS1Vd is a novel intronic splice variant first identified here. HAS1Vb, an intronic splice variant previously identified in patients, skips exon 4 and utilizes the same intron 4 alternative 3′splice site as HAS1Vd. For transfected constructs with unaltered introns 3 and 4, HAS1Vd transcripts are readily detectable, frequently to the exclusion of HAS1Vb. In contrast, in MM patients, HAS1Vb is more frequent than HAS1Vd. In the HAS1 minigene, combining deletion in intron 4 with mutations in intron 3 leads to a shift from HAS1Vd expression to HAS1Vb expression. The upregulation of aberrant splicing, exemplified here by the expression of HAS1Vb, is shown here to be influenced by multiple genetic changes in intronic sequences. For HAS1Vb, this includes enhanced exon 4 skipping and increased usage of alternative 3′ splice sites. Thus, the combination of introduced mutations in HAS1 intron3 with introduced deletions in HAS1 intron 4 promoted a shift to an aberrant splicing pattern previously shown to be clinically significant. Most MM patients harbor genetic variations in intron 4, and as shown here, nearly half harbor recurrent mutations in HAS1 intron 3. Our work suggests that aberrant intronic HAS1 splicing in MM patients may rely on intronic HAS1 deletions and mutations that are frequent in MM patients but absent from healthy donors.

Impact of age on outcomes after initial therapy with chemotherapy and different chemoimmunotherapy regimens in patients with chronic lymphocytic leukemia: results of sequential cancer and leukemia group B studies

PURPOSE

Chronic lymphocytic leukemia (CLL) is a disease of the elderly, yet few clinical trials include a significant number of older patients, and outcomes after specific therapies can be different depending on age.

PATIENTS AND METHODS

We examined patients enrolled onto successive first-line CALGB CLL trials to determine whether efficacy of regimens varied by age, focusing on ideal chemotherapy choice and benefit of immunotherapy addition to chemotherapy in older patients. Regimens included chlorambucil, fludarabine, fludarabine plus rituximab (FR), fludarabine with consolidation alemtuzumab, and FR with consolidation alemtuzumab.

RESULTS

A total of 663 patients were evaluated for response, progression-free survival (PFS), and overall survival (OS) by age group. Interaction effects of fludarabine versus chlorambucil by age group (PFS, P = .046; OS, P = .006) showed that among patients younger than 70 years, PFS and OS was improved with fludarabine over chlorambucil (PFS: hazard ratio [HR] = 0.6, 95% CI, 0.5 to 0.8; OS: HR = 0.7, 95% CI, 0.5 to 0.9), but not in older adults (PFS, HR = 1.0, 95% CI, 0.6 to 1.7; OS: HR = 1.5, 95% CI, 0.9 to 2.3). In contrast, FR improved outcomes relative to fludarabine, irrespective of age (PFS: HR = 0.6, 95% CI, 0.4 to 0.7; OS: HR = 0.7, 95% CI, 0.5 to 0.9). Alemtuzumab consolidation did not provide benefit over similar regimens without alemtuzumab (P > .20), irrespective of age.

CONCLUSION

These data support the use of chlorambucil as an acceptable treatment for many older patients with CLL and suggest rituximab is beneficial regardless of age. These findings bear relevance to both routine care of CLL patients 70 years and older and also future clinical trials in this population.

In multiple myeloma, bone-marrow lymphocytes harboring the same chromosomal abnormalities as autologous plasma cells predict poor survival

Chromosomal abnormalities in plasma cells (PCs) from multiple myeloma (MM) provide a clonal signature to identify malignant cells. BM-lymphocytes from MM aspirates, defined by stringent criteria, were screened for the same chromosomal abnormalities as autologous PCs, including translocations, deletions, and amplifications. For 200 MM patients, we evaluated BM mononuclear cells to identify lymphocytes and autologous PCs on the same slide, followed by interphase fluorescence in situ hybridization to characterize their chromosomal abnormalities. Of all patients having a given chromosomal abnormality(s) in PCs, 45% showed that same abnormality(s) in 2–37% (median = 5%) of BM-lymphocytes. Most translocations, amplifications, and deletions found in MM PCs were also detected in lymphocytes, above the healthy-donor “cut-off.” In patients having chromosomally abnormal CD20⁻ PCs, chromosomally abnormal lymphocytes were found among CD20+ cells confirming them as B cells. Exceptions were amplification of 1q21 or p53 deletion, which characterize PCs but were undetectable in BM-lymphocytes, suggesting that processes leading to these abnormalities may be exclusive to PCs. For a set of 75 patients whose BM-lymphocytes and PCs were analyzed by all six probe sets, 58% of those with abnormal PC also had abnormal BM-lymphocytes harboring from one to five different abnormalities. Confirming the clinical significance of chromosomally abnormal BM-lymphocytes, MM patients having abnormalities in both lymphocytes and PC had significantly worse survival than those with abnormalities only in PC (HR = 2.68). The presence of at least one chromosomal abnormality in BM-lymphocytes appears to have greater clinical significance than particular abnormalities. Chromosomally abnormal BM-lymphocytes correlate with poor outcome and by extrapolation with more aggressive disease.

Expression, adverse prognostic significance and therapeutic small molecule inhibition of Polo-like kinase 1 in multiple myeloma

The amplified myeloma centrosome has been identified as a therapeutic target. The present study explored the expression and prognostic significance of the centrosome-associated protein PLK1 in myeloma and the effect of BI 2536, a potent and selective inhibitor of PLK1, on myeloma cells. High plasma cell expression of PLK1 protein in myeloma patient bone marrow biopsies is an independent adverse prognostic factor (HR=2.3, p=0.003 unadjusted; HR=1.9, p=0.03 in multivariable model). BI 2536 inhibits myeloma cell lines at nanomolar concentrations, and is therapeutic for xenografts in NOD/SCID mice. PLK1 inhibition is a potential new strategy for the treatment of multiple myeloma.

Multiple myeloma may include microvessel endothelial cells of malignant origin

Multiple myeloma (MM) comprises B and plasma cell compartments that originate from the same parent B cell and share as a cancer signature the same clonotypic IgH VDJ gene rearrangement. Here, we hypothesize that functional interactions between MM plasma cells (MM-PC) and their sister population of MM monocytoid B cells lead to the generation of microvessel endothelium of malignant origin from the monocytoid B cell progenitors. Published reports confirm that endothelial cells can harbor a molecular cancer signature characteristic of a given malignancy. We predict that MM monocytoid B cells-in response to both paracrine and autocrine pathways-contribute to tumor neovascularization in the bone marrow of MM patients. Our hypothesis further predicts that in MM, endothelial cells of malignant origin coexist with those of normal origin. We speculate that malignant development of MM incorporates functionally distinct sister lineages arising from the same MM progenitor that-by working together-ensure survival of the MM clone. We hypothesize that these two arms of the malignant MM clone are functionally interlinked to promote growth of the MM-PC compartment; by providing its own microenvironment, MM clonal evolution may ensure neovascularization to support an expanding malignancy.

Genetic abnormalities in Waldenström's macroglobulinemia

The genetic factors that lead to WM are mostly unknown but are likely to involve inherited polymorphisms that might be markers of increased risk for developing WM, and somatic mutations that might be acquired during the events leading to oncogenesis and cancer progression. By intensive sequencing of the hyaluronan synthase 1 (HAS1) gene in malignant and normal cells from patients with WM, we have identified both types of mutation in HAS1 exons and introns. Acquired HAS1 mutations are found in malignant cells as well as presumptively nonmalignant CD34+ progenitor cells. This suggests that acquired HAS1 mutations precede frank malignancy and might contribute to the initial transforming events in WM as well as to disease progression.

Altered expression of fibronectin and collagens I and IV in multiple myeloma and monoclonal gammopathy of undetermined significance

Multiple myeloma (MM) is an incurable B-cell malignancy that arises in the bone marrow (BM). The malignant cells within the BM have extensive interaction with the structural components of their microenvironment. It has been previously shown that the interactions between MM cells and the BM extracellular matrix (ECM) proteins contribute to drug resistance. To understand the underlying causes of adhesion-mediated drug resistance in MM, the components of human BM ECM available for interactions with MM cells must be characterized. We analyzed the expression and localization of fibronectin, laminin, and collagens I and IV in the core biopsies of normal donors and patients with monoclonal gammopathy of undetermined significance (MGUS) or MM. In addition, we compared the patterns of ECM expression in MM patients with low-, mid-, and high-level plasmacytosis of the BM. Although expression of laminin was the same for all groups tested, levels of fibronectin and collagen I were reduced in MM patients with high-level plasmacytosis. Expression of collagen IV in the BM of MGUS and MM patients was higher than in the BM from normal donors. Compared with the plasma cells isolated from the patients with low- and mid-level plasmacytosis, sorted CD138(+) plasma cells from MM patients with high-level plasmacytosis overexpressed collagen IV. Our findings show that, compared with normal controls, the ECM composition of the bone, endosteum, and BM is aberrant in patients with MM, further establishing ECM as a key player in the MM disease process.

Multiple Myeloma Includes Phenotypically Defined Subsets of Clonotypic CD20+ B Cells that Persist During Treatment with Rituximab

Potential progenitor B cell compartments in multiple myeloma (MM) are clinically important. MM B cells and some circulating MM plasma cells express CD20, predicting their clearance by treatment with anti-CD20. Here we describe two types of clonotypic CD20+ B cell in peripheral blood of myeloma patients, identified by their expression of CD19 and CD20 epitopes, their expression of CD45RA and their light scatter properties. Thus, the circulating component of the MM clone includes at least two distinct CD19+ CD20+ B cell compartments, as well as CD138+ CD20+ plasma cells. To determine whether either or both B cell subsets and the CD20+ plasma cell subset were depleted by anti-CD20 therapy, they were evaluated before, during and after treatment of patients with rituximab (anti-CD20), followed by quantifying B cell subsets over a 5 month period during and after treatment. Overall, all three types of circulating B lineage cells persist despite treatment with rituximab. The inability of rituximab to prolong survival in MM may result from this failure to deplete CD20+ B and plasma cells in MM.

Microfluidic chips for detecting the t(4;14) translocation and monitoring disease during treatment using reverse transcriptase-polymerase chain reaction analysis of IgH-MMSET hybrid transcripts

Diagnosis platforms incorporating low-cost microfluidic chips enable sensitive, rapid, and accurate genetic analysis that could facilitate customized therapies tailored to match the vulnerabilities of any types of cancer. Using ex vivo cancer cells, we have detected the unique molecular signature and a chromosomal translocation in multiple myeloma. Multiple myeloma is characterized by IgH rearrangements and translocations that enable unequivocal identification of malignant cells, detected here with integrated microfluidic chips incorporating genetic amplification via reverse transcriptase-polymerase chain reaction and capillary electrophoresis. On microfluidic chips, we demonstrated accurate and versatile detection of molecular signatures in individual cancer cells, with value for monitoring response to therapy, detecting residual cancer cells that mediate relapse, and evaluating prognosis. Thus, testing for two clinically important molecular biomarkers, the IgH VDJ signature and hybrid transcripts signaling the t(4;14) chro-mosomal translocation, with predictive value in diagnosis, treatment decisions, and monitoring has been efficiently implemented on a miniaturized microfluidic system.

Concordant but not discordant bone marrow involvement in diffuse large B-cell lymphoma predicts a poor clinical outcome independent of the International Prognostic Index

In diffuse large B-cell lymphoma (DLBCL), previous studies have suggested that, while concordant bone marrow (BM) involvement confers a poor prognosis, discordant BM involvement does not. Whether this correlation is independent of the non-Hodgkin lymphoma International Prognostic Index (IPI) was previously unknown. We reviewed all DLBCL case histories from 1986 to 1997 at our center with complete staging, IPI data, and follow-up. A total of 55 (11.2%) of 489 patients had BM involvement, including 29 with concordant involvement and 26 with discordant involvement. The 55 patients with BM involvement had a poor prognosis compared with the uninvolved BM group (5-year overall survival [OS], 34.5% versus 46.9%; log-rank P = .019). However, concordant involvement portended a very poor prognosis (5-year OS, 10.3%; P < .001), whereas discordant involvement did not (5-year OS, 61.5%, P value nonsignificant). Compared with the discordant subset, the concordant subset patients were older, had a higher serum lactate dehydrogenase level, and a significantly higher IPI. However, the poor survival associated with concordant BM involvement was independent of the IPI score (P = .002, Cox regression). We conclude that in patients with DLBCL, concordant but not discordant BM involvement confers a very poor clinical outcome. Furthermore, concordant BM involvement is an independent adverse prognostic factor.

Molecular Characterization of Waldenstrom's Macroglobulinemia Reveals Frequent Occurrence of Two B-Cell Clones Having Distinct IgH VDJ Sequences

PURPOSE

Malignant B lineage cells in Waldenstrom's macroglobulinemia (WM) express a unique clonotypic IgM VDJ. The occurrence of biclonal B cells and their clonal relationships were characterized.

EXPERIMENTAL DESIGN

Bone marrow and blood from 20 WM patients were analyzed for clonotypic VDJ sequences, clonal B-cell frequencies, and the complementary determining region 3 profile.

RESULTS

Two different clonotypic VDJ sequences were identified in 4 of 20 WM. In two cases, partner clones had different VDJ rearrangements, with one clonotypic signature in bone marrow and a second in blood. For both cases, the bone marrow clone was hypermutated, whereas the blood clone was germ line or minimally mutated. In two other cases, partner clones shared a common VDJ rearrangement but had different patterns of somatic mutations. They lacked intraclonal diversity and were more abundant in bone marrow than in blood. VDJ mutation profiles suggested they arose from a common IgM progenitor. Single-cell analysis in one case indicated the partner clones were reciprocally expressed, following rules of allelic exclusion.

CONCLUSIONS

The existence of two B-cell clones having distinct VDJ sequences is common in WM, suggesting that frequent transformation events may occur. In two cases, the partner clones had distinct tissue distributions in either blood or bone marrow, were of different immunoglobulin isotypes, and in one case exhibited differential response to therapy. The contributions of each clone are unknown. Their presence suggests that WM may involve a background of molecular and cellular events leading to emergence of one or more malignant clones.

Ten years and counting: so what do we know about t(4;14)(p16;q32) multiple myeloma

Multiple myeloma is a genetically heterogenous disease with a wide variety of characterized genetic aberrations. Until recently, the impact of these aberrations on patient outcome was not known. However, in the last 5-10 years, several genetic markers have been linked to patient outcome. One of the strongest predictors of outcome identified to date is t(4;14)(p16;q32). Although this translocation is tightly linked to chromosome 13 deletions, another poor prognosis marker, it is becoming apparent that the translocation and not the deletion of 13 is the important factor. Unfortunately, despite the known association with outcome, an understanding of the mechanism(s) whereby the translocation contributes to developing and maintaining this aggressive form of myeloma remains elusive.

Understanding the Determinants of Exercise Intentions in Multiple Myeloma Cancer Survivors

The purpose of this study was to examine the demographic, medical, and social cognitive determinants of exercise intentions in a population-based sample of multiple myeloma cancer survivors. Using a cross-sectional survey, 70 multiple myeloma cancer survivors completed a questionnaire that assessed their medical and demographic characteristics, past exercise behavior, and social cognitive exercise beliefs using the theory of planned behavior. Seventy participants provided valuable data. Descriptive statistics indicated that participants had quite positive instrumental attitude, intentions, and subjective norms and moderate levels of perceived behavioral control and affective attitudes for exercise. Forced entry multiple regression showed that the theory of planned behavior explained 43% of the variance in exercise intentions. Instrumental attitude and perceived behavioral control were both independent predictors of exercise intentions. No demographic or medical variable moderated the association between the theory of planned behavior constructs and exercise intentions. The results of the present investigation support the growing body of evidence confirming the utility of the theory of planned behavior to understand the salient determinants of exercise in cancer survivors. Knowledge gained from this study provides important information to oncology practitioners who are responsible for delivering supportive care interventions, including exercise, to patients diagnosed with multiple myeloma.

SSX cancer testis antigens are expressed in most multiple myeloma patients: co-expression of SSX1, 2, 4, and 5 correlates with adverse prognosis and high frequencies of SSX-positive PCs

Cancer testis antigens (CTAs) are tumor-specific antigens that may be useful targets for cancer vaccines. Here, CTA expression was examined in multiple myeloma (MM), a B-cell cancer characterized by malignant plasma cells (PCs) in the bone marrow (BM), and monoclonal gammopathy of undetermined significance (MGUS), a condition that can progress to MM. We screened a panel of patient BMs at different stages of malignancy for CTA expression by reverse transcription polymerase chain reaction RT-PCR. Here, SSX (synovial sarcoma, X chromosome) emerged as a promising candidate for an MM vaccine, having a profile similar to currently studied CTA, NY-ESO-1, and MAGE. SSX1, 2, 4, and 5 expression was studied further in 114 MM (total SSX, 61% of patients; SSX1, 42%; SSX2, 23%; SSX4, 38%; SSX5, 35%), 45 MGUS (total SSX, 24% of patients; SSX1, 9%; SSX4, 20%), and 12 control (0/12, 0%) subjects. Several expression patterns were observed, the most predominant being co-expression of SSX1, 2, 4, and 5 (called group A expression, in 20% of MM), which correlated with reduced survival (P=0.0006). Of the four genes, SSX2 had the strongest association with reduced survival (P=0.0001). SSX protein expression ranged from 13.5% of PCs in an SSX1/SSX4 co-expressor to as high as 88% of PCs in group A expressor, exceeding reported frequencies of NY-ESO-1 and MAGE in MM. In single PCs from group A patients, we detected variable degrees of SSX co-expression, emphasizing the heterogeneity of CTA expression within tumor cell populations. These results demonstrate that SSX is a frequently expressed CTA in MM and highlight its potential as an MM vaccine candidate.

Impaired class switch recombination (CSR) in Waldenstrom macroglobulinemia (WM) despite apparently normal CSR machinery

Analysis of clonotypic isotype class switching (CSR) in Waldenström macroglobulinemia (WM) and IgM monoclonal gammopathy of undetermined significance (MGUS) reveals a normal initial phase of B-cell activation as determined by constitutive and inducible expression of activation-induced cytidine deaminase (AID). Switch mu (Smu) analysis shows that large deletions are not common in WM or IgM MGUS. In CD40L/IL-4-stimulated WM cultures from 2 patients, we observed clonotypic IgG exhibiting intraclonal homogeneity associated with multiple hybrid Smu/Sgamma junctions. This suggests CSR had occurred within WM cells. Nevertheless, the estimated IgG/IgM-cell frequency was relatively low (1/1600 cells). Thus, for the majority of WM B cells, CSR does not occur even when stimulated in vitro, suggesting that the WM cell is constitutively unable to or being prevented from carrying out CSR. In contrast to WM, the majority of IgM MGUS clones exhibit intraclonal heterogeneity of IgH VDJ. Furthermore, most IgM MGUS accumulate more mutations in the upstream Smu region than do WM, making them unlikely WM progenitors. These observations suggest that switch sequence analysis may identify the subset of patients with IgM MGUS who are at risk of progression to WM.

Sensitive detection using microfluidics technology of single cell PCR products from high and low abundance IgH VDJ templates in multiple myeloma

Human cancer is inherently heterogeneous, so the ability to monitor individual cancer cells at every clinic visit would be a valuable tool. This work describes the first step towards developing handheld and automated devices for molecular and phenotypic analysis of cancer cells. Here, we show that use of capillary electrophoresis to detect PCR product amplified from either transcripts (high abundance template) or genomic DNA (low abundance template) encoding clonotypic immunoglobulin heavy chain VDJ of plasma cells from patients with multiple myeloma. High abundance IgH VDJ transcripts amplified in conventional systems or by capillary electrophoresis through channels on microfluidic chips or, alternatively, PCR product amplified from individual myeloma plasma cells in a single stage RT-PCR reaction was readily detectable on microfluidic chips. For low abundance templates, a nested PCR strategy was needed to detect PCR product by any method. Using microfluidic chips, PCR products amplified from genomic IgH VDJ DNA were detected in six out of eight plasma cells. Comparison of the ABI3100 and the microfluidic chip indicates that approximately 20 times more sample is injected into the ABI 3100 capillary than for the microfluidics chip. Overall, for high and low abundance template in individual cells, the microfluidic separation/detection system is at least as sensitive as the ABI 3100. In the future, integrated microfluidic platforms that incorporate both PCR cycling and product detection on the same chip are likely to exceed conventional systems in sensitivity and speed of genetic analysis by RT-PCR or PCR.

Potential impact of a single nucleotide polymorphism in the hyaluronan synthase 1 gene in Waldenstrom's macroglobulinemia

The hyaluronan synthase 1 (HAS1) gene encodes a plasma membrane protein that synthesizes hyaluronan, an extracellular matrix molecule. Previously, in patients with Waldenstrom's macroglobulinemia (WM), we detected upregulation of HAS1 transcripts and identified aberrant splice variants of this gene. Aberrant splicing of HAS1 results from activation of cryptic splice sites. In turn, activation of cryptic donor and acceptor splice sites can be promoted by mutations occurring upstream of these sites and/or at the branch point of slicing. We measured the frequency of the HAS1 833A/G polymorphism (ie, single-nucleotide polymorphism; SNP) in patients with WM and healthy donors. Additionally, HAS1 gene expression was evaluated in the same group of patients. Our observations so far suggest that HAS1 833A/G SNPs contribute to aberrant splicing of this gene; this idea is supported by the fact that 833A/G SNP is located on an exonic splicing enhancer motif. Based on the results obtained thus far, we speculate that individuals with HAS1 833G/G genotype are predisposed toward aberrant HAS1 splicing and expression of HAS1 variants, resulting in an enhanced risk of developing WM. Study of a larger group of patients and healthy donors is needed to confirm these speculations and to evaluate the prognostic significance of these findings.

Association between exercise and quality of life in multiple myeloma cancer survivors

GOALS OF THE WORK

The goal of this study was to examine the association between exercise and quality of life (QOL) in multiple myeloma cancer survivors.

PATIENTS AND METHODS

Using a retrospective design, 156 multiple myeloma cancer survivors were mailed a questionnaire that assessed self-reported exercise behavior over three periods (prediagnosis, active treatment, and off-treatment) and QOL.

MAIN RESULTS

The response rate was 56% (88/ 156). Descriptive analyses indicated that 6.8% and 20.4% of survivors met national exercise guidelines during active and off-treatment periods, respectively. Exercise during active treatment and off-treatment were positively associated with overall QOL and all subdomains of QOL (all P<0.05) except physical wellbeing.

CONCLUSIONS

A low percentage of multiple myeloma cancer survivors are exercising regularly either during active or off-treatment periods. Survivors who report more exercise during these periods also report higher QOL. These findings suggest that a randomized controlled trial is warranted.

Origins of Waldenström's Macroglobulinemia: Does It Arise from an Unusual B-Cell Precursor?

Clonotypic B cells of Waldenstrom's macroglobulinemia (WM) are CD20+ immunoglobulin (Ig) M+ IgD+ cells that lack ongoing somatic hypermutation and class switch recombination (CSR). Only a small compartment of clonotypic B cells express activation-induced cytosine deaminase. Activation by CD40L/interleukin-4 does not stimulate WM class switching. However, we found that the mutation of switch regions essential for CSR were present in IgM monoclonal gammopathy of unknown significance (MGUS) but absent from WM B cells, suggesting the possibility that not all IgM MGUS have the potential to give rise to WM, and further strengthening the hypothesis that the target cell in transformation to WM is an unusual type of B cell.

Intronic splicing of hyaluronan synthase 1 (HAS1): a biologically relevant indicator of poor outcome in multiple myeloma

In this study, we show that the hyaluronan synthase 1 (HAS1) gene undergoes aberrant intronic splicing in multiple myeloma (MM). In addition to HAS1 full length (HAS1(FL)), we identify 3 novel splice variants of HAS1, HAS1Va, HAS1Vb, and HAS1Vc, detected in patients with MM or monoclonal gammopathy of undetermined significance (MGUS). HAS1Vb and HAS1Vc undergo intronic splicing with creation of a premature stop codon. MM cells expressing one or more HAS1 variants synthesize extracellular and/or intracellular hyaluronan (HA). Expression of the HAS1Vb splice variant was significantly correlated with reduced survival (P = .001). Together, alternative HAS1 gene splicing, the correlations between HAS1 splicing and HA synthesis, and the correlations between HAS1 splicing and reduced survival of MM patients support the hypothesis that the family of HAS1 protein plays a significant role in disease progression. Further, expression of HAS1Vb, in conjunction with HAS1(FL) and/or other HAS1 variants, may lead to accumulation of intracellular HA molecules and an impact on receptor for HA-mediated motility (RHAMM)-mediated mitotic abnormalities in MM. This study highlights the potential importance of HAS1 and its alternative splicing in pathophysiology of MGUS and MM.

Receptor for hyaluronan-mediated motility correlates with centrosome abnormalities in multiple myeloma and maintains mitotic integrity

Elevated expression of receptor for hyaluronan-mediated motility (RHAMM) within ex vivo diagnostic multiple myeloma plasma cells predicts for aggressive disease and patient survival. Here, we investigate the relationship between RHAMM and centrosomal abnormalities within multiple myeloma patient samples. We report that myeloma patient samples contain pervasive structural and numerical centrosomal abnormalities. Structural, but not numerical, centrosomal abnormalities strongly correlate with elevated RHAMM expression. As others have shown that excess pericentriolar material strongly associates with abnormal mitoses, we modeled centrosomal abnormalities with exogenous RHAMM overexpression. RHAMM overexpression in vitro resulted in centrosomal and mitotic defects. To elucidate a mechanism for RHAMM-mediated spindle defects, we further investigated RHAMM mitotic function. RHAMM mitotic localization mirrors that of targeting protein for Xklp2 (TPX2), and RHAMM interacts with the spindle assembly factors dynein and TPX2. Like TPX2, RHAMM expression is up-regulated during mitosis. Moreover, inhibition of function experiments reveals that RHAMM and TPX2 functions converge to maintain spindle integrity after spindle assembly. We postulate that augmentation of RHAMM expression within human cancers, including myeloma, can directly affect centrosomal structure and spindle integrity and potentially modulate apoptotic and cell cycle progression pathways.

Receptor for Hyaluronan-Mediated Motility Correlates with Centrosome Abnormalities in Multiple Myeloma and Maintains Mitotic Integrity

Elevated expression of receptor for hyaluronan-mediated motility (RHAMM) within ex vivo diagnostic multiple myeloma plasma cells predicts for aggressive disease and patient survival. Here, we investigate the relationship between RHAMM and centrosomal abnormalities within multiple myeloma patient samples. We report that myeloma patient samples contain pervasive structural and numerical centrosomal abnormalities. Structural, but not numerical, centrosomal abnormalities strongly correlate with elevated RHAMM expression. As others have shown that excess pericentriolar material strongly associates with abnormal mitoses, we modeled centrosomal abnormalities with exogenous RHAMM overexpression. RHAMM overexpression in vitro resulted in centrosomal and mitotic defects. To elucidate a mechanism for RHAMM-mediated spindle defects, we further investigated RHAMM mitotic function. RHAMM mitotic localization mirrors that of targeting protein for Xklp2 (TPX2), and RHAMM interacts with the spindle assembly factors dynein and TPX2. Like TPX2, RHAMM expression is up-regulated during mitosis. Moreover, inhibition of function experiments reveals that RHAMM and TPX2 functions converge to maintain spindle integrity after spindle assembly. We postulate that augmentation of RHAMM expression within human cancers, including myeloma, can directly affect centrosomal structure and spindle integrity and potentially modulate apoptotic and cell cycle progression pathways.

Overexpression of transcripts originating from the MMSET locus characterizes all t(4;14)(p16;q32)-positive multiple myeloma patients

Multiple myeloma (MM) is a B-lineage malignancy characterized by diverse genetic subtypes and clinical outcomes. The recurrent immunoglobulin heavy chain (IgH) switch translocation, t(4;14)(p16;q32), is associated with poor outcome, though the mechanism is unclear. Quantitative reverse-transcription-polymerase chain reaction (RT-PCR) for proposed target genes on a panel of myeloma cell lines and purified plasma cells showed that only transcripts originating from the WHSC1/MMSET/NSD2 gene are uniformly dysregulated in all t(4;14)POS patients. The different transcripts detected, multiple myeloma SET domain containing protein (MMSET I), MMSET II, Exon 4a/MMSET III, and response element II binding protein (RE-IIBP), are produced by alternative splicing and alternative transcription initiation events. Translation of the various transcripts, including those from major breakpoint region 4-2 (MB4-2) and MB4-3 breakpoint variants, was confirmed by transient transfection and immunoblotting. Green fluorescent protein (GFP)-tagged MMSET I and II, corresponding to proteins expressed in MB4-1 patients, localized to the nucleus but not nucleoli, whereas the MB4-2 and MB4-3 proteins concentrate in nucleoli. Cloning and localization of the Exon 4a/MMSET III splice variant, which contains the protein segment lost in the MB4-2 variant, identified a novel protein domain that prevents nucleolar localization. Kinetic studies using photobleaching suggest that the breakpoint variants are functionally distinct from wild-type proteins. In contrast, RE-IIBP is universally dysregulated and also potentially functional in all t(4;14)POS patients irrespective of fibroblast growth factor receptor 3 (FGFR3) expression or breakpoint type.

Results of a Multicenter Randomized Phase II Trial of Thalidomide and Prednisone Maintenance Therapy for Multiple Myeloma after Autologous Stem Cell Transplant

We report a multicenter, randomized phase II trial conducted to assess the tolerability of combined thalidomide and prednisone maintenance in multiple myeloma. Eligibility required administration of melphalan (200 mg/m2) with blood stem cell support within 1 year of treatment onset and initiation of maintenance within 60 to 100 days after stem cell infusion. All patients received 50 mg of prednisone by mouth on alternate days and thalidomide at a starting dose of either 200 or 400 mg daily by mouth. The primary end point was the incidence of dropout or dose reduction due to treatment toxicity within 6 months. Sixty-seven patients were enrolled. Median follow-up is 36.8 months. The primary end point was reached by 31% of patients on the 200 mg of thalidomide arm and 64% of patients on the 400 mg of thalidomide arm. Allowing for dose reduction, 76% of patients assigned to the 200 mg of thalidomide arm and 41% of patients assigned to the 400 mg of thalidomide arm remained on any maintenance therapy 18 months after registration. Eighty-eight percent of all patients dose-reduced thalidomide and 72% of all patients dose-reduced prednisone within 2 years of beginning maintenance. The median progression-free survival post-transplant is 32.3 months, or 42.2 months from diagnosis. Only the 200 mg of thalidomide arm of this trial met our definition of a tolerable maintenance therapy, defined as no dose reductions or discontinuation due to toxicity in at least 65% of patients for a minimum of 6 months, thus establishing a dosing schedule for phase III trials.

RHAMM expression and isoform balance predict aggressive disease and poor survival in multiple myeloma

Multiple myeloma (MM) plasma cells (PCs) express receptor for hyaluronan-mediated motility (RHAMM), a hyaluronan-binding, cytoskeleton and centrosome protein. The most abundant RHAMM isoforms in MM are full-length RHAMM (RHAMMFL) and the splice variant RHAMM-exon4. We separately examined the significance of RHAMM expression, and isoform balance, in 2 groups of MM patients. In oligonucleotide microarray experiments (n=210, Arkansas), increasing RHAMM mRNA expression in MM PCs is strongly associated with osteolytic bone lesions (P <.001), and event-free (P =.05) and overall (P =.04) survival. Semiquantitative determination of RHAMM isoform expression (Alberta, Canada) used capillary electrophoretic detection and measurement of RHAMM-exon4/RHAMMFL reverse-transcriptase-polymerase chain reaction (RT-PCR) products. RHAMM isoforms are rarely expressed concurrently in single MM PCs; the pattern of isoform expression, at the single-cell level, is approximated in larger numbers of cells by the RHAMM-exon4/RHAMMFL ratio. Absolute RHAMM expression and the RHAMM-exon4/RHAMMFL ratio are only partially correlated in MM PCs; in cell lines, absolute RHAMM expression is elevated in mitosis, while RHAMM ratios remain stable. Temporal examination of MM patients' peripheral blood reveals that the RHAMM-exon4/RHAMMFL ratio increases with disease burden. The RHAMM-exon4/RHAMMFL ratio in diagnostic bone marrow samples (n=101, Alberta) is an independent prognostic factor. Thus, expression and splicing of RHAMM are important molecular determinants of disease severity in MM.

Clonotypic IgM V/D/J sequence analysis in Waldenstrom macroglobulinemia suggests an unusual B-cell origin and an expansion of polyclonal B cells in peripheral blood

Analysis of clonotypic immunoglobulin M (IgM) from 15 patients with Waldenstrom macroglobulinemia (WM) showed a strong preferential use of the VH3/JH4 gene families. Identification of the WM IgM V/D/J was validated using single-cell analysis, confirming its presence in most B cells. Despite the extensive hypermutated VH genes in 13 of 15 patients, statistical analysis of framework/complementary-determining region (FR/CDR) mutation patterns suggests that they might have escaped antigenic selection. Neither intraclonal diversity nor isotype switching was detectable. Membranous and secreted forms of clonotypic IgM transcripts were present in bone marrow and blood. Single-cell analysis showed that clonotypic B cells coexpress CD20, surface IgM (sIgM), and sIgD but that they lack CD138. Most B cells lacked memory marker CD27 despite their hypermutated variable regions otherwise suggestive of memory status. At diagnosis, circulating B cells in WM are largely clonotypic. However, when monoclonal IgM levels are decreased, clonotypic frequencies are substantially reduced despite elevated CD20+ cells, shown to be polyclonal by DNA sequencing and CDR3 fragment analysis. Thus, WM includes the expansion of circulating, polyclonal B cells. Overall, this work suggests that WM may originate from a largely VH3-restricted, somatically mutated, predominantly CD27(-)IgM(+)IgD+ population that cannot undergo class switching, suggestive of B cells that might have bypassed the germinal center.