T-cell subpopulations in patients with monoclonal gammopathies: essential monoclonal gammopathy, multiple myeloma, and Waldenstrom macroglobulinemia

T-cell subsets defined by monoclonal antibodies (OKT3, OKT4, and OKT8) were analyzed in 117 patients with monoclonal gammopathies--69 multiple myeloma (MM) (30 untreated and 39 treated), 14 Waldenstr?m's macroglobulinaemia (WM), and 34 essential monoclonal gammopathy (EMG) patients. The percentage and absolute numbers of total T-lymphocytes (E+, OKT3+ cells) were within the normal range in all groups except for the treated MM patients, in which a decrease in the absolute number could be observed. The percentages of OKT4+ cells were significantly lower in MM (35 +/- 1.7) than in EMG patients (43 +/- 2) and controls (50 +/- 2). In contrast, OKT8 cells correspondingly increased in MM (38 +/- 1.6) compared with EMG patients (29 +/- 1) and controls (27 +/- 1). The OKT4/OKT8 ratio was lower in MM than that in EMG patients and controls (p less than 0.01) and was shown to be one of the four most significant variables in a linear discriminant analysis used to distinguish between MM and EMG groups. The MM patients in clinical stage III as well as Bence-Jones myeloma patients showed a more pronounced OKT4/OKT8 imbalance. The treatment did not influence the percent distribution of T-cell subpopulations. The patients with WM exhibit an alteration in the distribution of the T-cell subsets similar to the MM patients with a T4/T8 ratio of 1.1 +/- 0.1. This imbalance was more pronounced in WM patients with monoclonal B-lymphocytes in peripheral blood (leukaemic phase of WM). The functional significance of the altered T-cell subsets in MM and WM patients remains to be established, though it is probable that such an imbalance plays an important role in regulating these B-cell proliferations.     

Targeting PI3‐kinase (PI3K), AKT and mTOR axis in lymphoma

Targeted therapy represents a transformation in oncology, a field that has relied primarily on non‐selective cytotoxic therapies. Phosphatidylinositol 3‐kinase (PI3K) is a family of ubiquitous signalling molecules involved in a wide variety of cellular processes and likewise, in a broad selection of human cancers. The discovery that the p110‐δ form of PI3K is differentially expressed in normal and malignant lymphocytes has led to the development of specific inhibitors that are currently in clinical trials for lymphoma. Downstream effectors of PI3K, including v‐akt murine thymoma viral oncogene homolog 1 (AKT; also termed AKT1) and mechanistic target of rapamycin (serine/threonine kinase) (mTOR) are similarly important in lymphoma, and agents targeting these components of the PI3K‐AKT‐mTOR axis are also underway, although at earlier stages of development. In this review we examine the role of PI3K‐AKT‐mTOR in normal and malignant lymphocytes, as well as the preclinical and clinical status of a number of inhibitors of this pathway.     

Activity of any class IA PI3K isoform can sustain cell proliferation and survival

Small molecule inhibitors of PI3K for oncology mainly target the class I PI3Ks, comprising the p110α, β, γ, and δ isoforms, of which only p110α is mutated in cancer. To assess the roles of class I PI3K isoforms in cell proliferation and survival, we generated immortalized mouse leukocyte and fibroblast models in which class I PI3Ks were inactivated by genetic and pharmacological approaches. In IL3-dependent hemopoietic progenitor cells (which express all four class I PI3K isoforms), genetic inactivation of either p110α or p110δ did not affect cell proliferation or survival or sensitize to p110β or p110γ inactivation. Upon compound inactivation of p110α and p110δ, which removed >90% of p85-associated PI3K activity, remarkably, cells continued to proliferate effectively, with p110β assuming an essential role in signaling and cell survival. Furthermore, under these conditions of diminished class I PI3K activity, input from the ERK pathway became important for cell survival. Similar observations were made in mouse embryonic fibroblasts (which mainly express p110α and p110β) in which p110α or p110β could sustain cell proliferation as a single isoform. Taken together, these data demonstrate that a small fraction of total class I PI3K activity is sufficient to sustain cell survival and proliferation. Persistent inhibition of selected PI3K isoforms can allow the remaining isoform(s) to couple to upstream signaling pathways in which they are not normally engaged. Such functional redundancy of class IA PI3K isoforms upon sustained PI3K inhibition has implications for the development and use of PI3K inhibitors in cancer.     

Recombinant interferon gamma in hairy cell leukemia, multiple myeloma, and Waldenstrom's macroglobulinemia

Fifteen patients with multiple myeloma, five with hairy cell leukemia, and five with Waldenstrom's macroglobulinemia were treated with recombinant interferon gamma (rINF-gamma) to determine the antitumor activity of this agent. The rIFN-gamma was administered by daily intramuscular injection at doses ranging from 0.125 to 0.5 mg/m2. No responses were observed in patients with multiple myeloma, although in one patient the disease has remained stable for over 16 months. Minimal improvement in some hematologic indexes were observed in three of five patients with hairy cell leukemia. One partial remission and one minor response were documented in two of the five patients with Waldenstrom's macroglobulinemia. In five patients, an increase in normal serum immunoglobulins was observed. These results suggest that there is only minimal activity of rIFN-gamma as a single agent in neoplasms of B-cell origin.     

Phase I/II study exploring ImMucin,a pan‐major histocompatibility complex,anti‐MUC1 signal peptide vaccine,in multiple myeloma patients

ImMucin, a 21‐mer cancer vaccine encoding the signal peptide domain of the MUC1 tumour‐associated antigen, possesses a high density of T‐ and B‐cell epitopes but preserves MUC1 specificity. This phase I/II study assessed the safety, immunity and clinical response to 6 or 12 bi‐weekly intradermal ImMucin vaccines, co‐administered with human granulocyte‐macrophage colony‐stimulating factor to 15 MUC1‐positive multiple myeloma (MM) patients, with residual or biochemically progressive disease following autologous stem cell transplantation. Vaccination was well tolerated; all adverse events were temporal grade 1 2 and spontaneously resolved. ImMucin vaccination induced a robust increase in γ‐interferon (IFN‐γ‐producing CD4+ and CD8+ T‐cells (≤80‐fold), a pronounced population of ImMucin multimer CD8+ T‐cells (>2%), a 9·4‐fold increase in peripheral blood mononuclear cells proliferation and 6·8‐fold increase in anti‐ImMucin antibodies, accompanied with T‐cell and antibody‐dependent cell‐mediated cytotoxicity. A significant decrease in soluble MUC1 levels was observed in 9/10 patients. Stable disease or improvement, persisting for 17·5‐41·3 months (ongoing) was achieved in 11/15 patients and appeared to be associated with low‐intermediate PDL1 (CD274) bone marrow levels pre‐ and post‐vaccination. In summary, ImMucin, a highly tolerable cancerous vaccine, induces robust, diversified T‐ and B‐cell ImMucin‐specific immunity in MM patients, across major histocompatibility complex‐barrier, resulting in at least disease stabilization in most patients.     

Cyproheptadine‐induced myeloma cell apoptosis is associated with inhibition of the PI3K/AKT signaling

Recent studies revealed that the anti‐allergic cyproheptadine displays anti‐blood cancer activity. However, its mechanism is still elusive. In this study, cyproheptadine was found to decrease the expression of anti‐apoptotic proteins, including Bcl‐2, Mcl‐1, and XIAP. More importantly, cyproheptadine‐induced apoptosis was accompanied by suppressing AKT activation in myeloma cells. In the subsequent study, cyproheptadine was found to inhibit insulin‐like growth factor 1‐triggered AKT activation in a time‐ and concentration‐dependent manner. Specifically, cyproheptadine blocked AKT translocation from nuclei for phosphorylation. This inhibition led to suppressed activation of p70S6K and 4EBP1, two key downstream signaling proteins in the PI3K/AKT pathway. However, cyproheptadine did not display inhibition on activation of IGF‐1R or STAT3, possible upstream signals of AKT activation. These results further demonstrated that cyproheptadine suppresses the PI3K/AKT signaling pathway, which is probably critical for cyproheptadine‐induced MM cell apoptosis.     

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

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

Combined targeting of MEK/MAPK and PI3K/Akt signalling in multiple myeloma

So-called RAS-dependent pathways, such as those signalling via mitogen-activated protein kinase kinase (MEK)/mitogen-activated protein kinase (MAPK) and phosphoinositide-3 kinase (PI3K)/Akt, are implicated in proliferation and survival of multiple myeloma (MM) cells. However, the effects of their combined blockade and its potential therapeutic utility for the treatment of RAS-mutated MM have not systematically been analysed. Here, we tested the functional consequences of single versus combined inhibition of the MEK/MAPK and PI3K/Akt pathways in a large series of primary MM samples (n = 55) and MM cell lines (n = 11). Additionally, the anti-myeloma activity of different treatments was analysed with respect to the RAS mutation status. PI3K/Akt blockade was generally more pro-apoptotic than blockade of MEK/MAPK both in cell lines and in primary MM samples. Simultaneous blockade of both pathways led to significantly enhanced anti-myeloma activity in 75% of primary MM samples, whereas the remainder was largely resistant. Resistance to combination blockade was exclusively observed in RAS wildtype cases, whereas sensitivity was noted in RAS wildtype and in RAS mutated MM. These results suggest that oncogenic RAS is a predictor of sensitivity to combination treatment with PI3K/Akt and MEK/MAPK inhibitors and that such an approach might therefore be beneficial for this genetically well-defined subgroup of MM patients.     

Dexamethasone,rituximab and cyclophosphamide for relapsed and/or refractory and treatment‐naïve patients with Waldenstrom macroglobulinemia

The management of Waldenström macroglobulinaemia (WM) relies predominantly on small trials, one of which has demonstrated activity of dexamethasone, rituximab and cyclophosphamide (DRC) in the frontline setting. We report on the efficacy of DRC, focusing on relapsed/refractory (R/R) patients. Ibrutinib, a recently approved agent in WM demonstrated limited activity in patients with MYD88^WT genotype. Herein, we additionally report on the activity of DRC based on the MYD88^L265P mutation status. Of 100 WM patients evaluated between January 2007 and December 2014 who received DRC, 50 had R/R WM. The overall response rate (ORR) was 87%. The median progression‐free survival (PFS) and time‐to‐next‐therapy (TTNT) were 32 (95% confidence interval [CI]: 15–51) and 50 (95% CI: 35–60) months, respectively. In the previously untreated cohort (n = 50), the ORR was 96%, and the median PFS and TTNT were 34 months (95% CI: 23–not reached [NR]) and NR (95% CI: 37–NR), respectively. Twenty‐five (86%) of 29 genotyped patients harbored MYD88^L265P. The response rates and outcomes were independent of MYD88 mutation status. Grade ≥3 adverse effects included neutropenia (20%), thrombocytopenia (7%) and infections (3%). Similar to the frontline setting, DRC is an effective and well‐tolerated salvage regimen for WM. In contrast to ibrutinib, DRC offers a less expensive, fixed‐duration option, with preliminary data suggesting efficacy independent of the patients’ MYD88 status.     

Inherited and acquired variations in the hyaluronan synthase 1 (HAS1) gene may contribute to disease progression in multiple myeloma and Waldenstrom macroglobulinemia

To characterize genetic contributions toward aberrant splicing of the hyaluronan synthase 1 (HAS1) gene in multiple myeloma (MM) and Waldenstrom macroglobulinemia (WM), we sequenced 3616 bp in HAS1 exons and introns involved in aberrant splicing, from 17 patients. We identified a total of 197 HAS1 genetic variations (GVs), a range of 3 to 24 GVs/patient, including 87 somatic GVs acquired in splicing regions of HAS1. Nearly all newly identified inherited and somatic GVs in MM and/or WM were absent from B chronic lymphocytic leukemia, nonmalignant disease, and healthy donors. Somatic HAS1 GVs recurred in all hematopoietic cells tested, including normal CD34(+) hematopoietic progenitor cells and T cells, or as tumor-specific GVs restricted to malignant B and plasma cells. An in vitro splicing assay confirmed that HAS1 GVs direct aberrant HAS1 intronic splicing. Recurrent somatic GVs may be enriched by strong mutational selection leading to MM and/or WM.     

Insulin-like growth factor I is a growth and survival factor in human multiple myeloma cell lines

Human multiple myeloma (MM) represents a highly aneuploid tumor as shown by cytogenetic studies. This may partly explain the heterogeneity with regard to growth factor requirements demonstrated among MM cells. We have previously reported the expression of insulin-like growth factor I (IGF-I) and IGF-I receptor (IGF-IR) mRNA in some MM cell lines. In this study we investigated the role of IGF-I as a growth and/or survival factor in three MM cell lines: LP-1, EJM, and Karpas 707. We report that all cell lines expressed IGF-I and IGF-IR mRNA and protein. LP-1 and Karpas 707, but not EJM, were stimulated to proliferation in a dose-dependent manner by exogenous IGF-I. An IGF-IR blocking antibody inhibited both the IGF-I-induced and spontaneous growth of LP-1, and Karpas 707, while the EJM cell line was unaffected by the addition of the antibody. In conclusion, our results show that IGF-I can act as a growth factor in human MM, and they suggest that an autocrine IGF-I loop may contribute to the growth and survival in some MM cell lines.     

The phosphatidylinositol 3‐kinases (PI3K) inhibitor GS‐1101 synergistically potentiates histone deacetylase inhibitor‐induced proliferation inhibition and apoptosis through the inactivation of PI3K and extracellular signal‐regulated kinase pathways

Previously, we showed that inhibition of the protein kinase C β (PKCβ)/AKT pathway augments engagement of the histone deacetylase inhibitor (HDI)‐induced apoptosis in lymphoma cells. In the present study, we investigated the cytotoxicity and mechanisms of cell death induced by the delta isoform‐specific phosphatidylinositide 3‐kinase (PI3K) inhibitor, GS‐1101, in combination with the HDI, panobinostat (LBH589) and suberoylanilide hydroxamic acid (SAHA). Lymphoma cell lines, primary non‐Hodgkin Lymphoma (NHL) and chronic lymphocytic leukaemia (CLL) cells were simultaneously treated with the HDI, LBH589 and GS‐1101. An interaction of the LBH589/GS‐1101 combination was formally examined by using various concentrations of LBH589 and GS‐1101. Combined treatment resulted in a synergistic inhibition of proliferation and showed synergistic effect on apoptotic induction in all tested cell lines and primary NHL and CLL cells. This study indicates that interference with PI3K signalling dramatically increases HDI‐mediated apoptosis in malignant haematopoietic cells, possibly through both AKT‐dependent or AKT‐ independent mechanisms. Moreover, the increase in HDI‐related apoptosis observed in PI3K inhibitor‐treated cells appears to be related to the disruption of the extracellular signal‐regulated kinase (ERK) signalling pathway. This study provides a strong rational for testing the combination of PI3K inhibitors and HDI in the clinic.     

HLA class I and class II antigens associated with multiple myeloma in southern Africa

While the exact aetiology of myeloma is unknown, genetic factors feature among the potential risk factors. The HLA phenotypes in African blacks with myeloma (the commonest haematopoietic malignancy in this group) have not been characterized. The purpose of this study was to determine the HLA class I and class II phenotypes of patients with multiple myeloma and to compare the findings to an ethnically matched control group of 100 individuals. Analysis of the HLA class I and class II phenotypes in 62 myeloma patients revealed: (i) a corresponding statistically significant association with HLA B18 [odds ratio (OR) 6.3; 95% confidence interval (CI) 1.013-39.727; P < 0.005]; (ii) no statistically significant association with HLA B13, Cw2, Cw6 or the DR and DQ antigens; and (iii) a statistically significant negative (protective) association with HLA Cw7 (OR 0.4; 95% CI 0.21-0.87; P < 0.005). This study suggests that although genetic factors may play a role in the multifactorial aetiology of multiple myeloma, with the exception of HLA B18, there is no specific association between HLA types and multiple myeloma in South African blacks.     

LY294002, a PI3K inhibitor,attenuates Tourette syndrome in rats

Metabolic Brain Disease - The present study was designed to investigate the effects of LY294002 on Tourette syndrome (TS) in rats. TS model was induced in rats by DOI (the selective 5-HT2A/2C...