Search

Waldenström macroglobulinaemia ( WM) is a rare and incurable lymphoma. Given that the survival of WM patients can be prolonged, our objective was to describe trends in overall survival ( OS) and analyse competing risks of death in patients with WM. The analysis included 5784 patients diagnosed with WM between 1991 and 2010 from the Surveillance, Epidemiology and End Results ( SEER) database. Multivariate hazard models for OS and cumulative incidence of death were fitted according to epoch of diagnosis (1991-2000 vs. 2001-10) while adjusting for age, sex, race, histology, site of involvement and registry. Median OS for the 1991-2000 and the 2001-10 cohorts was 6 and 8 years, respectively ( P < 0·001). In the multivariate analysis, better OS [hazard ratio ( HR) 0·73, 95% confidence interval ( CI) 0·67-0·79; P < 0·001] was seen in the 2001-10 cohort. Survival benefits were identified, for the 2001-10 cohort, in almost every stratum analysed, with the exception of patients aged <50 years and blacks. In the multivariate competing-risk analysis, the 2001-10 cohort experienced lower rates of WM-related ( HR 0·57, 95% CI 0·49-0·66; P < 0·001) and non- WM-related deaths ( HR 0·72, 95% CI 0·66-0·79; P < 0·001). In conclusion, there have been significant improvements in OS, WM-related and non- WM-related mortality in patients with WM diagnosed in the last decade. [ABSTRACT FROM AUTHOR]

CXCR4 WHIM frameshift and nonsense mutations follow MYD88L265P as the most common somatic variants in Waldenström Macroglobulinaemia ( WM), and impact clinical presentation and ibrutinib response. While the nonsense ( CXCR4S338X) mutation has been investigated, little is known about CXCR4 frameshift ( CXCR4FS) mutations. We engineered WM cells to express CXCR4FS mutations present in patients, and compared their CXCL12 ( SDF-1a) induced signalling and ibrutinib sensitivity to CXCR4wild-type (WT) and CXCR4S338X cells. Following CXCL12 stimulation, CXCR4FS and CXCR4S338X WM cells showed impaired CXCR4 receptor internalization, and enhanced AKT1 (also termed AKT) and MAPK1 (also termed ERK) activation versus CXCRWT cells ( P < 0·05), though MAPK1 activation was more prolonged in CXCR4S338X cells ( P < 0·05). CXCR4FS and CXCR4S338X cells, but not CXCR4WT cells, were rescued from ibrutinib-triggered apoptosis by CXCL12 that was reversed by AKT1, MAPK1 or CXCR4 antagonists. Treatment with an inhibitor that blocks MYD88L265P signalling triggered similar levels of apoptosis that was not abrogated by CXCL12 treatment in CXCR4WT and CXCR4WHIM cells. These studies show a functional role for CXCR4FS mutations in WM, and provide a framework for the investigation of CXCR4 antagonists with ibrutinib in CXCR4WHIM-mutated WM patients. Direct inhibition of MYD88L265P signalling overcomes CXCL12 triggered survival effects in CXCR4WHIM-mutated cells supporting a primary role for this survival pathway in WM. [ABSTRACT FROM AUTHOR]

In Waldenström macroglobulinaemia ( WM), the mechanism(s) responsible for repression of B-cell differentiation remains unknown. We found that expression of SPIB and ID 2 were significantly increased and decreased, respectively, in WM lymphoplasmacytic cells ( LPC). Ectopic expression of SPIB in healthy donor CD19+ cells inhibited plasmacytic differentiation in conjunction with decreased transcription of IRF 4 and XBP 1 spliced form. In primary WM LPC, knock-down of SPIB induced plasmacytic differentiation in conjunction with increased transcription of PRDM 1, XBP 1 spliced form, IRF 4 and ID 2. Knock-down of SPIB also led to decreased BCL 2 expression. Given that SPIB is a direct target of POU 2 AF 1 ( OBF 1) in complex with POU 2 F 2 or POU 2 F 1, we next examined their expression in WM LPC. POU 2 F 2 transcription, as well as POU2F2 and POU2 AF1 protein expression was higher in WM LPC. Ectopic expression of POU 2 F 2 in healthy donor CD19+ cells induced transcription of SPIB and suppressed transcription of PRDM 1 and IRF 4. Chromatin immunoprecipitation analysis in BCWM.1 WM cells confirmed binding of POU2F2 and POU2 AF1 in SPIB and ID 2 promoters. These findings establish a molecular hierarchy among POU 2 F 2, SPIB and ID 2 during B-cell differentiation, and suggest that aberrant expression of these transcription factors plays an important role in arresting plasmacytic differentiation in WM. [ABSTRACT FROM AUTHOR]

The article presents research on the use of hematologic drug Idelalisib in treating patients with Waldenström macroglobulinemia (WM). Topics discussed include an overview of Waldenström macroglobulinemia, the activation of phosphatidylinositol-3-kinase (PI3K) pathway, and the benefit of idelalisib to patients..

The article focuses on a study regarding the role of B-cell selection in determination of the MYD88 mutation status in waldenstrom macroglobulinemia (WM). It mentions that WM is characterized by bone marrow (BM) with lymphoplasmacytic lymphoma and helps in the production of a monoclonal immunoglobulin (Ig) M protein. It also mentions the importance of MYD88 mutational status in diagnostic, prognostic and treatment of WM patients.

The article presents a study which examined the therapeutic use of rituximab in patients with Waldenström macroglobulinemia (WM). The variables considered include the median age and sex distribution of patients at rituximab intolerance, common symptoms leading toward rituximab discontinuation and median immunoglobulins M (IgM). The result of a review of trials using rituximab in WM patients are mentioned.

Sp1 transcription factor controls a pleiotropic group of genes and its aberrant activation has been reported in a number of malignancies, including multiple myeloma. In this study, we investigate and report its aberrant activation in Waldenström macroglobulinemia (WM). Both loss of and gain of Sp1 function studies have highlighted a potential oncogenic role of Sp1 in WM. We have further investigated the effect of a small molecule inhibitor, terameprocol (TMP), targeting Sp1 activity in WM. Treatment with TMP inhibited the growth and survival and impaired nuclear factor-κB and signal transducer and activator of transcription activity in WM cells. We next investigated and observed that TMP treatment induced further inhibition of WM cells in MYD88 knockdown WM cells. Moreover, we observed that Bruton's tyrosine kinase, a downstream target of MYD88 signaling pathway, is transcriptionally regulated by Sp1 in WM cells. The combined use of TMP with Bruton's tyrosine kinase or interleukin-1 receptor-associated kinase 1 and 4 inhibitors resulted in a significant and synergistic dose-dependent antiproliferative effect in MYD88-L265P--expressing WM cells. In summary, these results demonstrate Sp1 as an important transcription factor that regulates proliferation and survival of WM cells independent of MYD88 pathway activation, and provide preclinical rationale for clinical development of TMP in WM alone or in combination with inhibitors of MYD88 pathway. [ABSTRACT FROM AUTHOR]

The genetic basis for Waldenström macroglobulinemia (WM) remains to be clarified. Although 6q losses are commonly present, recurring gene losses in this region remain to be defined. We therefore performed whole genome sequencing (WGS) in 30 WM patients, which included germline/tumor sequencing for 10 patients. Validated somatic mutations occurring in >10% of patients included MYD88, CXCR4, and ARID1A that were present in 90%, 27%, and 17% of patients, respectively, and included the activating mutation L265P in MYD88 and warts, hypogammaglobulinemia, infection, and myelokathexis-syndrome-like mutations in CXCR4 that previously have only been described in the germline. WGS also delineated copy number alterations (CNAs) and structural variants in the 10 paired patients. The CXCR4 and CNA findings were validated in independent expansion cohorts of 147 and 30 WM patients, respectively. Validated gene losses due to CNAs involved PRDM2 (93%), BTG1 (87%), HIVEP2 (77%), MKLN1 (77%), PLEKHG1 (70%), LYN(60%), ARID1B(50%), and FOXP1 (37%). Losses in PLEKHG1, HIVEP2, ARID1B, and BCLAF1 constituted the most common deletions within chromosome 6. Although no recurrent translocations were observed, in 2 patients deletions in 6q corresponded with translocation events. These studies evidence highly recurring somatic events, and provide a genomic basis for understanding the pathogenesis of WM. [ABSTRACT FROM AUTHOR]

Myeloid differentiation factor 88 (MYD88) L265P somatic mutation is highly prevalent in Waldenström macroglobulinemia (WM) and supports malignant growth through nuclear factor κB (NF-κB). The signaling cascade(s) by which MYD88 L265P promotes NF-κB activation in WM remain unclear. By lentiviral knockdown or use of a MYD88 inhibitor, decreased phosphorylation of the NF-κB gatekeeper IκBα and survival occurred in MYD88 L265P-expressing WM cells. Conversely, WM cells engineered to overexpress MYD88 L265P showed enhanced survival. Coimmunoprecipitation studies identified Bruton tyrosine kinase (BTK) complexed to MYD88 in L265P-expressing WM cells, with preferential binding of MYD88 to phosphorylated BTK (pBTK). Increased pBTK was also observed in WM cells transduced to overexpress L265P vs wild-type MYD88. Importantly, MYD88 binding to BTK was abrogated following treatment of MYD88 L265P-expressing cells with a BTK kinase inhibitor. Inhibition of BTK or interleukin-1 receptor-associated kinase 1 and 4 (IRAK-1 and -4) kinase activity induced apoptosis of WM cells, and their combination resulted in more robust inhibition of NF-κB signaling and synergistic WM cell killing. The results establish BTK as a downstream target of MYD88 L265P signaling, and provide a framework for the study of BTK inhibitors alone, and in combination with IRAK inhibitors for the treatment of WM. [ABSTRACT FROM AUTHOR]

By whole-genome and/or Sanger sequencing, we recently identified a somatic mutation (MYD88 L265P) that stimulates nuclear factor κB activity and is present in >90% of Waldenström macroglobutinemia (WM) patients. MYD88 L265P was absent in 90% of immunoglobulin M (IgM) monoclonal gammopathy of undetermined significance (MGUS) patients. We therefore developed conventional and real-time allele-specific polymerase chain reaction (AS-PCR) assays for more sensitive detection and quantification of MYD88 L265P. Using either assay, MYD88 L265P was detected in 97 of 104 (93%) WM and 13 of 24 (54%) IgM MGUS patients and was either absent or rarely expressed in samples from splenic marginal zone lymphoma (2/20; 10%), CLL (1/26; 4%), multiple myeloma (including IgM cases, 0/14), and immunoglobulin C MGUS (0/9) patientsas well as healthy donors (0/40; P < 1.5 × 10-5 for WM vs other cohorts). Real-time AS-PCR identified IgM MGUS patients progressing to WM and showed a high rate of concordance between MYD88 L265P ΔCT and BM disease involvement (r = 0.89, P = .008) in WM patients undergoing treatment. These studies identify MYD88 L265P as a widely present mutation in WM and IgM MGUS patients using highly sensitive and specific AS-PCR assays with potential use in diagnostic discrimination and/or response assessment. The finding of this mutation in many IgM MGUS patients suggests that MYD88 L265P may be an early oncogenic event in WM pathogenesis. [ABSTRACT FROM AUTHOR]

Bruton tyrosine kinase (Btk) has a welldefined role in B-cell development, whereas its expression in osteoclasts (OCs) further suggests a role in osteoclastogenesis. Here we investigated effects of PCI-32765, an oral and selective Btk Inhibitor, on osteoclastogenesis as well as on multiple myeloma (MM) growth within the BM microenvironment. PCI-32765 blocked RANKL/M-CSF-induced phosphorylation of Btk and downstream PLC-&ggr;2 In OCs, resulting In diminished TRAP5b ((ED50 = 17nM) and bone resorption activity. PCI-32765 also Inhibited secretion of multiple cytokines and chemokines from OC and BM stromal cell cultures from both normal donors (ED50 = 0.5nM) and MM patients. It decreased SDF-1-Induced migration of MM cells, and down-regulated MIP1-&agr;/CCL3 in MM cells. It also blocked MM cell growth and survival triggered by IL-6 or coculture with BM stromal cells or OCs in vitro. Importantly, PCI-32765 treatment significantly inhibits in vivo MM cell growth (P < .03) and MM cell-induced osteolysis of Implanted human bone chips in SCID mice. Moreover, PCI-32765 prevents in vitro colony formation by stem-like cells from MM patients. Together, these results delineate functional sequelae of Btk activation mediating osteolysis and growth of MM cells, supporting evaluation of PCI-32765 as a novel therapeutic in MM. [ABSTRACT FROM AUTHOR]

Abstract: Background: Little is known about the epidemiology and etiology of Waldenstrom macroglobulinemia (WM). Despite several studies of the relation between family history and B-cell disorders and WM, family history of non-hematologic cancers has not been systematically investigated. We thus examined associations of family history of breast, colorectal, lung, ovarian, and prostate cancers with WM. Methods: All probands aged 20–79 years with bone marrow biopsy-confirmed diagnosis of WM between May 1, 1999 and January 1, 2010 at the Bing Center for Waldenstrom Macroglobulinemia were eligible for inclusion in our analysis. We reviewed medical records for eligible probands to determine family history of cancer (defined as a cancer diagnosis for ≥1 first-degree relative(s) of the proband). Using expected values constructed from the United States National Health Interview Survey, we estimated age- and race-standardized rate ratios (RRs) for family history of breast, colorectal, lung, ovarian, and prostate cancers by WM subtype. Results: Family history of prostate cancer had the largest overall rate ratio (RR=1.4, 95% confidence limits [CL]: 1.1, 1.7), and among sporadic cases, family history of prostate and breast cancer had the largest rate ratios (prostate: RR=1.3, 95% CL: 1.1, 1.7; breast: RR=1.3, 95% CL: 1.2, 1.6). Conclusion: Our study suggests that it may be worthwhile to pursue these associations in a case–control study with uniform selection and data collection for cases and controls, and at least some record-based information on family history. [Copyright &y& Elsevier]

Histone deacetylases (HDACs) are aberrantly expressed, and inhibitors of HDACs induce apoptosis in lymphoplasmacytic cells (LPCs) in Waldenström macroglobulinemia (WM). The molecular profile by which these agents induce apoptosis in WM LPCs remains to be delineated. We examined the activity of the histone deacetylase inhibitor, vorinostat, and dissected its pro-apoptotic pathways in WM LPCs. Vorinostat induced apoptosis in WM cells through activating specific caspases at varying times. Inhibitors of apoptosis (IAPs) were down-regulated after vorinostat treatment. Cellular stress induced in vorinostat-treated WM cells was reflected by changes in the mitogen activated protein kinase (MAPK) pathways. Activated phospho-p38 MAPK was up-regulated at 12 h, while phospho-extracellular signal-regulated kinase (Erk) abruptly decreased at 24 h. Bortezomib did not augment vorinostat induced primary WM cell killing as reported in other B-cell disorders. These studies support that stress induced apoptosis in vorinostat-treated WM LPCs is mediated through disrupting the activity of the Erk and p38 MAPK pathways. [ABSTRACT FROM AUTHOR]

Waldenstrom Macroglobulinemia (WM) is a B-cell malignancy characterized by excess bone marrow (BM) lymphoplasmacytic cells (LPC). The accumulation of LPC in WM may represent a failure of B-cells to properly differentiate into plasma cells. The present study investigated transcriptional expression of genes involved in late B-cell differentiation, including PRDM1, PAX5, XBP1 transcripts and ERN1, in BM B-cells from 31 patients with WM and six healthy donors. Real time reverse transcription polymerase chain reaction (RT-PCR) determined that approximately 80% of the patients had high XBP1 spliced mRNA expression, 80% of whom had high mRNA ERN1α expression. XBP1, PRDM1 and PAX5 mRNA was present in all patients studied. Using relative quantitative RT-PCR we isolated two groups with low and high expression of XBP1, XBP1 spliced and ERN1α. Sequence analysis showed germline polymorphisms in all genes studied. These data depict for the first time a heterogeneous expression pattern of the genes involved in late differentiation process of plasma cells in patients with WM and propose a role of XBP1-ERN1α in WM pathogenesis. [ABSTRACT FROM AUTHOR]

Waldenstrom macroglobulinaemia (WM) is an incurable lymphoplasmacytic lymphoma with secretion of serum monoclonal immunoglobulin M (IgM). We previously showed that patients receiving cholesterol-lowering statins, had the lowest IgM value in a large cohort of patients with WM. Simvastatin, a 3-hydroxy-3-methyl-glutaryl-CoA reductase inhibitor, induced inhibition of proliferation, cytotoxic effect and apoptosis in IgM secreting cell lines as well as in primary CD19+ WM cells. Interestingly, those effects were reversed by addition of mevalonate and geranylgeranylpyrophosphate, demonstrating that simvastatin inhibited cell growth, survival and IgM secretion on BCWM.1 WM cells by inhibition of geranylgeranylated proteins. Furthermore, simvastatin overcame tumour cell growth induced by co-culture of WM cells with bone-marrow stromal cells. Simvastatin also decreased IgM secretion by BCWM.1 cells at an early time-point that had not affected cell survival. Simvastatin-induced cytotoxicity was preceded by a decrease in Akt (protein kinase B, PKB) and extracellular signal-regulated kinase (ERK) mitogen-activated protein kinase (MAPK) pathways at 18 h. In addition, simvastatin induced an increase in stress-activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK) MAPK followed by caspase-8, -9, -3 and poly(ADP-ribose) polymerase (PARP) cleavages at 18 h, leading to apoptosis. Furthermore, simvastatin enhanced the cytotoxicity induced by bortezomib, fludarabine and dexamethasone. Our studies therefore support our earlier observation of statin-mediated anti-WM activity and provide the framework for future clinical trials testing simvastatin in WM. [ABSTRACT FROM AUTHOR]

The serum IgM level has been utilised as a marker of tumor progression and to assess response to therapy in patients with Waldenstrom macroglobulinemia (WM). However, there are many limitations to the IgM protein level. The objective of this study was to evaluate the association of known tumor burden markers and prognostic factors with serum free light chain (sFLC) in 98 patients with WM. We demonstrated that sFLC measurement accurately differentiated IgM-MGUS compared with WM reflecting a measurement of tumor burden. In univariate and multivariate analysis, median sFLC at the cut-off at 60 mg/L was higher for WM patients with low hemoglobin and high β2M, when we applied the WM-IPSS cut-offs, but showed no association with IgM level. This study demonstrates that sFLC is a new marker in WM disease. Further analysis is required to prospectively study the role of sFLC in monitoring response to therapy and as a prognostic marker in WM patients. [ABSTRACT FROM AUTHOR]

Objectives: Waldenstrom Macroglobulinemia (WM) is a B-cell neoplasm characterised by secretion of IgM by lymphoplasmacytic bone marrow cells and by cytopenias and hypogammaglobulinemia in a subset of patients. Beta-2 microglobulin (b2m) is a major prognostic factor in WM and the heavy chain of HLA class I molecules, which are known to have immunosuppressive properties and have been implicated in the pathogeny of several malignancies. Methods: We assessed the serum levels of the total soluble HLA-I molecules and the HLA-Gs molecules in 105 patients with IgM-related disorders [WM ( n = 42) and IgM MGUS ( n = 63)], and compared the results to 41 healthy subjects. Results: We found higher levels of HLA-Is in WM, compared to IgM MGUS and healthy donors. HLA-Gs levels were similar in WM and in IgM MGUS, but higher than in healthy donors. The association between HLA-Is at the cut-off of 1.8 μg/mL and known markers of poor prognosis was then evaluated among WM patients using univariate and multivariate methods. Based on this, high HLA-Is level was strongly associated with high serum β2M level >3 mg/L [OR = 2, (CI 95% 1.1–5.7); P = 0.04], age > 65 yrs [OR = 1.5, (CI 95% 0.5–4.1), P = 0.06] and haemoglobin ≤11.5 g/dL [OR = 3.3, (CI 95% 1.2–9.7); P = 0.03]. High levels of serum HLA-Is were also found in patients with cryoglobulinemia, however irrespectively of WM or IgM-MGUS status. Conclusion: Together our results suggest a possible role for soluble MHC class I molecules in WM disease. Further investigations are necessary to further demonstrate the prognostic impact of soluble MHC class I molecules in Waldenstrom Macroglobulinemia. [ABSTRACT FROM AUTHOR]

Background. Alemtuzumab is an emerging therapy for refractory lymphoproliferative disorders. The associated long-term risks of infection remain poorly defined. Methods. From July 2001 through December 2003, all patients who received alemtuzumab for the treatment of lymphoproliferative disorders at 1 institution underwent a retrospective evaluation to document infectious complications until death or end of follow-up in October 2004. Alemtuzumab recipients who underwent allogeneic hematopoietic stem cell transplantation were compared with a concurrent cohort who also underwent allogeneic hematopoietic stem cell transplantation but did not receive alemtuzumab. Results. Twenty-seven patients were identified (21 with chronic lymphocytic leukemia and 6 with plasma cell disorders). The overall mortality was 37%, with 7 of 10 deaths being related to infection. Significant opportunistic infections occurred in 9 patients (43%) with chronic lymphocytic leukemia, including cytomegalovirus, progressive multifocal leukoencephalopathy, adenovirus, toxoplasmosis, and acanthamaebiasis. Thirty nonopportunistic infections in 22 patients (82%) were also identified. The 3 deaths related to nonopportunistic infections all involved Enterococcus species bacteremia. When compared with a concurrent chronic lymphocytic leukemia cohort that underwent allogeneic hematopoietic stem cell transplantation, alemtuzumab recipients had an incidence of cytomegalovirus reactivation of 66.7% (6 of 9 patients), compared with 37% in the non-alemtuzumab group (10 of 27 patients; P = .15), and an incidence of post-transplant opportunistic infections (excluding herpesviruses) of 44.4% (compared with 29.6% in the non-alemtuzumab group; P = .41). Conclusions. Despite the use of herpesvirus and Pneumocystis pneumonia prophylaxis, serious infectious complications occur in patients receiving alemtuzumab for lymphoproliferative disorders. Infectious complications are more varied and diverse in patients receiving alemtuzumab than has been reported in trials to date. [ABSTRACT FROM AUTHOR]

Thalidomide and immunomodulatory drugs (IMiDs), which target multiple myeloma (MM) cells and the bone marrow microenvironment, can overcome drug resistance. These agents also have immunomodulatory effects. Specifically, we have reported that thalidomide increased serum interleukin-2 (IL-2) levels and natural killer (NK) cell numbers in the peripheral blood of responding MM patients. In this study, we investigated the mechanisms whereby IMiDs augment NK cell cytotoxicity. NK cytotoxicity and antibody-dependent cell-mediated cytotoxicity (ADCC) of peripheral blood mononuclear cells cultured with IMiDs were examined in the presence or absence of anti-IL-2 antibody, ciclosporin A or depletion of CD56-positive cells. IMiDs-induced signalling pathways, triggering IL-2 transcription in T cells, were also delineated. IMiDs facilitated the nuclear translocation of nuclear factor of activated T cells-2 and activator protein-1 via activation of phosphoinositide-3 kinase signalling, with resultant IL-2 secretion. IMiDs enhanced both NK cell cytotoxicity and ADCC induced by triggering IL-2 production from T cells. These studies defined the mechanisms whereby IMiDs trigger NK cell-mediated tumour-cell lysis, further supporting their therapeutic use in MM. [ABSTRACT FROM AUTHOR]

Multiple myeloma (MM) cells express certain tumour-associated antigens (TAAs) that could serve as targets for active-specific immunotherapy. The aim of the present study was to test the MM/dendritic cell (DC) fusion as a vaccination strategy. We fused MM cells with DC to generate fusion cells (FCs) and tested their antigen presenting cell (APC) function in mixed lymphocyte reactions and cytotoxicity assays. First, the HS Sultan and SK0-007 HAT sensitive human MM cell lines and DCs generated from peripheral blood of normal donors were fused in the presence of 50% polyethylene glycol to form FCs. Next, tumour cells freshly isolated from patients were similarly fused with autologous DCs to generate FCs. The FCs demonstrated a biphenotypic profile, confirmed both by flow-cytometry and dual immunofluorescence microscopy. These FCs induced MM-specific cytotoxicity. FCs, but not MM cells or DCs alone, were potent stimulators of autologous patient T cells. More importantly, FC-primed autologous peripheral blood mononuclear cells demonstrated major histocompatibility complex-restricted MM-specific cytolysis. These studies therefore demonstrated that MM/DC FC can trigger an autologous immune response to MM cells and formed the framework for a clinical trial currently underway. [ABSTRACT FROM AUTHOR]

The proteasome inhibitor PS-341 inhibits IκB degradation, prevents NF-κB activation, and induces apoptosis in several types of cancer cells, including chemoresistant multiple myeloma (MM) cells. PS-341 has marked clinical activity even in the setting of relapsed refractory MM. However, PS-341-induced apoptotic cascade(s) are not yet fully defined. By using gene expression profiling, we characterized the molecular sequelae of PS-341 treatment in MM cells and further focused on molecular pathways responsible for the anticancer actions of this promising agent. The transcriptional profile of PS-341-treated cells involved down-regulation of growth/survival signaling pathways, and up-regulation of molecules implicated in proapoptotic cascades (which are both consistent with the proapoptotic effect of proteasome inhibition), as well as up-regulation of heat-shock proteins and ubiquitin/proteasome pathway members (which can correspond to stress responses against proteasome inhibition). Further studies on these pathways showed that PS-341 decreases the levels of several antiapoptotic proteins and triggers a dual apoptotic pathway of mitochondrial cytochrome c release and caspase-9 activation, as well as activation of Jun kinase and a Fas/caspase-8-dependent apoptotic pathway [which is inhibited by a dominant negative (decoy) Fas construct]. Stimulation with IGF-1, as well as overexpression of Bcl-2 or constitutively active Akt in MM cells also modestly attenuates PS-341-induced cell death, whereas inhibitors of the BH3 domain of Bcl-2 family members or the heat-shock protein 90 enhance tumor cell sensitivity to proteasome inhibition. These data provide both insight into the molecular mechanisms of antitumor activity of PS-341 and the rationale for future clinical trials of PS-341, in combination with conventional and novel therapies, to improve patient outcome in MM. [ABSTRACT FROM AUTHOR]

Presents a study that demonstrated the functions of insulin-like growth factor-1. Inducement of phosphorylation of the FKHRL-1 Forkhead transcription factor; Upregulation of a series of intracellular anti-apoptotic proteins; Effect on Apo2L/TRAIL-sensitivity of multiple myeloma cells.

Summary Heterobifunctional molecules that recruit E3 ubiquitin ligases, such as cereblon, for targeted protein degradation represent an emerging pharmacological strategy. A major unanswered question is how generally applicable this strategy is to all protein targets. In this study, we designed a multi-kinase degrader by conjugating a highly promiscuous kinase inhibitor with a cereblon-binding ligand, and used quantitative proteomics to discover 28 kinases, including BTK, PTK2, PTK2B, FLT3, AURKA, AURKB, TEC, ULK1, ITK, and nine members of the CDK family, as degradable. This set of kinases is only a fraction of the intracellular targets bound by the degrader, demonstrating that successful degradation requires more than target engagement. The results guided us to develop selective degraders for FLT3 and BTK, with potentials to improve disease treatment. Together, this study demonstrates an efficient approach to triage a gene family of interest to identify readily degradable targets for further studies and pre-clinical developments. [ABSTRACT FROM AUTHOR]

Oncogenic “driver” mutations are theoretically attractive targets for the immunotherapy of lymphoid cancers, yet the proportion that can be recognized by T cells remains poorly defined. To address this issue without any confounding effects of the patient's immune system, we assessed T cells from 19 healthy donors for recognition of three common driver mutations in lymphoma:MYD88L265P, EZH2Y641F, andEZH2Y641N. Donors collectively expressed the 10 most prevalent HLA class I alleles, including HLA-A*02:01. Peripheral blood T cells were primed with peptide-loaded dendritic cells (DC), and reactive T cells were assessed for recognition of naturally processed mutant versus wild type full-length proteins. After screening three driver mutations across 17–26 HLA class I alleles and 3 × 106−3 × 107T cells per donor, we identified CD4+T cells against EFISENCGEII from EZH2Y641N(presented by HLA-DRB1*13:02) and CD8+T cells against RPIPIKYKA from MYD88L265P(presented by HLA-B*07:02). We failed to detect RPIPIKYKA-specific T cells in seven other HLA-B*07:02-positive donors, including two lymphoma patients. Thus, healthy donors harbor T cells specific for common driver mutations in lymphoma. However, such responses appear to be rare due to the combined limitations of antigen processing, HLA restriction, and T cell repertoire size, highlighting the need for highly individualized approaches for selecting targets. [ABSTRACT FROM PUBLISHER]

A letter to the editor in response to the article "Survival Trends in Waidenström Macroglobuilnemia: An Analysis of the Surveillance, Epidemiology and End Results Database," that was published in a previous issue of the journal is presented.