Autotransplant with and without induction chemotherapy in older multiple myeloma patients: long-term outcome of a randomized trial.

Autologous transplantation is controversial for older patients with multiple myeloma. The role of age-adjusted high-dose melphalan and the impact of induction chemotherapy cycles is still unclear. A total of 434 patients aged 60-70 years were randomly assigned to 4 cycles of standard anthracycline-based induction chemotherapy or no induction. For all patients, double autologous transplantation after melphalan 140 mg/m2 (MEL140) was planned. The primary end point was progression-free survival. Of 420 eligible patients, 85% received a first transplant and 69% completed double transplantation. Treatment duration was short with a median of 7.7 months with induction chemotherapy cycles and 4.6 months without induction. On an intention-to-treat basis, median progression-free survival with induction chemotherapy cycles (207 patients) was 21.4 months versus 20.0 months with no induction cycles (213 patients) (hazard ratio 1.04, 95% confidence interval 0.84-1.28; P=0.36). Per protocol, progression-free survival was 23.7 months versus 23.0 months (P=0.28). Patients aged 65 years or over (55%) did not have an inferior outcome. Patients with low-risk cytogenetics [absence of del17p13, t(4;14) and 1q21 gains] showed a favorable overall survival and included the patients with sustained first remission. MEL140 was associated with a low rate of severe mucositis (10%) and treatment-related deaths (1%). Based on hazard ratio, the short treatment arm consisting of mobilization chemotherapy and tandem MEL140 achieved 96% of the progression-free survival, demonstrating its value as an independent component of therapy in older patients with multiple myeloma who are considered fit for autologous transplantation. (clinicaltrials.gov identifier: 02288741).

Testing G-CSF responsiveness predicts the individual susceptibility to infection and consecutive treatment in recipients of high-dose chemotherapy.

The individual risk of infection and requirements for medical treatment after high-dose chemotherapy have been unpredictable. In this prospective, multicenter, open-label study we investigated the potential of granulocyte colony-stimulating factor (G-CSF) responsiveness as a predictor. A total of 168 patients with multiple myeloma or lymphoma received a single dose of subcutaneous G-CSF (lenograstim, 263 µg) after high-dose chemotherapy. Highly variable leukocyte peaks were measured and grouped as low (quartile 1; leukocytes 100-10 100/µL), medium (quartile 2; leukocytes > 10 100-18 300/µL), and high (quartiles 3/4; leukocytes > 18 300-44 800/µL). G-CSF responsiveness (low vs medium vs high) was inversely correlated with febrile neutropenia (77% vs 60% vs 48%; P = .0037); the rate of infection, including fever of unknown origin (91% vs 67% vs 54%; P < .0001); days with intravenous antibiotics (9 vs 6 vs 5; P < .0001); and antifungal therapy (P = .042). In multivariate analysis, G-CSF responsiveness remained the only factor significantly associated with infection (P = .016). In addition, G-CSF responsiveness was inversely correlated with grade 3/4 oral mucositis (67% vs 33% vs 23%; P < .0001). G-CSF responsiveness appears as a signature of the myeloid marrow reserve predicting defense against neutropenic infection after intensive chemotherapy. This study is registered at http://www.clinicaltrials.gov as NCT01085058.

Dendritic cell-based vaccination of patients with advanced pancreatic carcinoma: results of a pilot study.

BACKGROUND AND AIMS: Dendritic cell (DC)-based vaccination can induce antitumor T cell responses in vivo. This clinical pilot study examined feasibility and outcome of DC-based tumor vaccination for patients with advanced pancreatic adenocarcinoma. METHODS: Tumor lysate of patients with pancreatic carcinoma was generated by repeated freeze-thaw cycles of surgically obtained tissue specimens. Patients were eligible for DC vaccination after recurrence of pancreatic carcinoma or in a primarily palliative situation. DC were generated from peripheral blood mononuclear cells (PBMC), loaded with autologous tumor lysate, stimulated with TNF-α and PGE(2) and injected intradermally. All patients received concomitant chemotherapy with gemcitabine. Disease response was the primary endpoint. Individual immunological responses to DC vaccination were analyzed by T cell-based immunoassays using pre- and post-vaccination samples of non-adherent PBMC. RESULTS: Twelve patients received DC vaccination and concomitant chemotherapy. One patient developed a partial remission, and two patients remained in stable disease. Median survival was 10.5 months. No severe side effects were observed. Tumor-reactive T cells could be detected prior to vaccination. DC vaccination increased the frequency of tumor-reactive cells in all patients tested; however, the degree of this increase varied. To quantify the presence of tumor-reactive T cells, stimulatory indices (SI) were calculated as the ratio of proliferation-inducing capacity of lysate-loaded versus -unloaded DC. The patient with longest overall survival of 56 months had a high SI of 6.49, indicating that the presence of a pre-vaccination antitumor T cell response might be associated with prolonged survival. Five patients survived 1 year or more. CONCLUSION: DC-based vaccination can stimulate an antitumoral T cell response in patients with advanced or recurrent pancreatic carcinoma receiving concomitant gemcitabine treatment.

First-line therapy with fludarabine compared with chlorambucil does not result in a major benefit for elderly patients with advanced chronic lymphocytic leukemia.

Although chronic lymphocytic leukemia (CLL) is a disease of elderly patients, subjects older than 65 years are heavily underrepresented in clinical trials. The German CLL study group (GCLLSG) initiated a multicenter phase III trial for CLL patients older than 65 years comparing first-line therapy with fludarabine with chlorambucil. A total of 193 patients with a median age of 70 years were randomized to receive fludarabine (25 mg/m(2) for 5 days intravenously, every 28 days, for 6 courses) or chlorambucil (0.4 mg/kg body weight [BW] with an increase to 0.8 mg/kg, every 15 days, for 12 months). Fludarabine resulted in a significantly higher overall and complete remission rate (72% vs 51%, P = .003; 7% vs 0%, P = .011). Time to treatment failure was significantly shorter in the chlorambucil arm (11 vs 18 months; P = .004), but no difference in progression-free survival time was observed (19 months with fludarabine, 18 months with chlorambucil; P = .7). Moreover, fludarabine did not increase the overall survival time (46 months in the fludarabine vs 64 months in the chlorambucil arm; P = .15). Taken together, the results suggest that in elderly CLL patients the first-line therapy with fludarabine alone does not result in a major clinical benefit compared with chlorambucil. This trial is registered with www.isrctn.org under identifier ISRCTN 36294212.

Prognostic model for newly diagnosed CLL patients in Binet stage A: results of the multicenter, prospective CLL1 trial of the German CLL study group.

The heterogeneity of early stage CLL challenges prognostication, and refinement of prognostic indices for risk-adapted management in this population is essential. The aim of the multicenter, prospective CLL1 trial was to explore a novel prognostic model (CLL1-PM) developed to identify risk groups, separating patients with favorable from others with dismal prognosis. A cohort of 539 clinically, biochemically, and genetically characterized Binet stage A patients were observed until progression, first-line treatment, or death. Multivariate analysis identified six independent factors associated with overall survival (OS) and time-to-first treatment (TTFT): del(17p), unmutated IGHV, del(11q), ß2-microglobulin >3.5 mg/dL, lymphocyte doubling time (LDT) <12 months, and age >60 years. These factors were integrated into the CLL1-PM, which stratified patients into four risk groups. The CLL1-PM was prognostic for OS and TTFT, e.g., the risk of treatment at 5 years was 85.9, 51.8, 27.6, and 11.3% for very low (0-1.5), low (2-4), high (4.5-6.5), and very high-risk (7-14) scores, respectively (P < 0.001). Notably, in addition to factors comprising CLL-IPI, we substantiated del(11q) and LDT as prognostic factors in early CLL. Altogether, our findings would be useful to effectively stratify Binet stage A patients, particularly within the scope of clinical trials evaluating novel agents.

AML M1 presenting with recurrent acute large arterial vessel thromboembolism.

Acute leukemia may be associated with coagulopathy, predominantly severe bleeding diathesis caused by disseminated intravascular coagulation (DIC) and/or hyperfibrinolysis. Disordered hemostasis is characteristic for acute promyelocytic leukemia (APL, FAB M3). However, thromboembolic events such as arterial occlusion localized to the large vessels at presentation is very rare and almost exclusively linked to APL. We report a case of severe recurrent acute arterial thromboembolism at presentation in AML FAB M1. Most likely, the ischemic events in our patient resulted from leukemia as the thrombus material included many leukemic blasts. The thrombotic complications resulted in leg amputation in this patient. Despite leg amputation just a couple of hours before and extremely high infectious risk of the patient, chemotherapy was administered. The clinical course of cessation of the ischemic events and a fast reduction of the blasts in the peripheral blood smear after chemotherapeutic treatment of the patient outlines the importance and life saving role of early chemotherapy even under adverse circumstances.

Inhibition of lymphocyte function associated antigen 1 by LFA878 induces apoptosis in multiple myeloma cells and is associated with downregulation of the focal adhesion kinase/phosphatidylinositol 3 kinase/Akt pathway.

Multiple myeloma (MM) is still an incurable disease and adhesion of MM cells to bone marrow stromal cells is one of the hallmarks of the disease. Lymphocyte function associated antigen 1 (LFA-1) is an adhesion molecule that mediates lymphocyte adhesion, but its role in MM is only poorly understood. The aim of the presented study was to improve knowledge on LFA-1 and associated pathways in MM for the development of molecular targeted therapies. We demonstrate that LFA-1 is expressed in U266, RPMI-8226, OPM-2, and NCI-H929 MM cell lines and in primary cells of eight tested patients. The LFA-1 inhibitor LFA878 induces apoptosis in all four cell lines as revealed by annexin V staining and caspase 3 cleavage. Apoptosis is not hampered by adhesion to stromal cells. Additionally, the soluble ligand, intracellular adhesion molecule 1 (ICAM-1), which is increased in the serum of MM patients, does not protect from melphalan-induced apoptosis. Western blots demonstrate downregulation of FAK, PI3-K, and Akt upon LFA878 treatment. Additionally, sequential inhibition of the pathway by simultaneous application of Src family kinase or PI3-K inhibitors significantly increases LFA878 induced apoptosis. We conclude that LFA-1/FAK/PI3-K/Akt is a survival pathway in MM and that targeted inhibition may provide new therapeutic options.

Evaluation of chemosensitivity of human bone marrow stromal cells--differences between common chemotherapeutic drugs.

BACKGROUND: Bone marrow stromal cells (BMSCs) are essential for normal hematopoiesis, but also support the growth and survival of malignant hematopoietic cells. There are currently no data available regarding the sensitivity of BMSCs to cytotoxic drugs widely used in the therapy of hematological diseases such as multiple myeloma or acute leukemia. MATERIALS AND METHODS: The chemosensitivity of the BMSC line HS-5 and of primary BMSCs from patients were evaluated in comparison to NCI-H929 myeloma and U937 leukemia cells. RESULTS: Both HS-5 cells and human BMSCs showed substantial cell death in response to chemotherapy. While alkylating agents (melphalan, treosulfan) and doxorubicin demonstrated marked BMSC toxicity, nucleotide analogs (gemcitabine, cytarabine) induced only limited BMSC apoptosis. CONCLUSION: Our data suggest that the BMSC toxicity of cytotoxic compounds should be considered in chemotherapeutic regimens.

B-cell lymphomas differ in their responsiveness to CpG oligodeoxynucleotides.

Human B cells detect CpG motifs within microbial DNA via TLR9. Synthetic CpG oligodeoxynucleotides are currently being tested in clinical trials for the therapy of different types of B cell non-Hodgkin's lymphoma. However, there is only limited information on the CpG oligodeoxynucleotide sensitivity of primary malignant B cells of different non-Hodgkin's lymphoma entities. Here we found that most B-cell malignancies except plasmacytoma respond to CpG oligodeoxynucleotides by up-regulating expression of costimulatory and antigen-presenting molecules, by increasing expression of CD20, and by proliferation. In an in vitro analysis of 41 individual patient-derived primary tumor samples, B-cell chronic lymphocytic leukemia (B-CLL) and marginal zone lymphoma showed the strongest activation upon stimulation with CpG oligodeoxynucleotides. Small lymphocytic lymphoma, follicular lymphoma, mantle cell lymphoma, and large cell lymphoma showed an intermediate response. Consistent with CpG oligodeoxynucleotides sensitivity, TLR9 mRNA was present in B-CLL but absent in plasmacytoma. Although CpG oligodeoxynucleotides induced proliferation in all CpG oligodeoxynucleotide-sensitive types of B-cell malignancies, proliferation was weaker than in normal B cells and at least for B-CLL was followed by increased apoptosis. In conclusion, B-cell malignancies show significant differences in their responsiveness to CpG oligodeoxynucleotides. Focusing clinical studies on patients with highly CpG oligodeoxynucleotide-sensitive B-cell malignancies may improve the clinical outcome of such trials.

Efficacy of bendamustine in patients with relapsed or refractory chronic lymphocytic leukemia: results of a phase I/II study of the German CLL Study Group.

BACKGROUND AND OBJECTIVES: Although bendamustine has been used for more than 30 years in the treatment of lymphoma, little is known about the optimal dosing schedule in relapsed or refractory B-cell chronic lymphocytic leukemia (CLL). Various dose and treatment schedules have been used empirically, and several phase II studies have shown impressive efficacy. To determine the maximal tolerated dose, dose-limiting toxicity and the optimal therapeutic dose of bendamustine for further phase III clinical trials the GCLLSG designed a phase I/II study for pre-treated CLL patients. DESIGN AND METHODS: Sixteen patients (median age 67 years) with relapsed or refractory CLL were enrolled. All patients had been pre-treated with a median of three different regimens. Bendamustine was given at a starting dose of 100 mg/m2 on day 1 and 2, repeated every 3-4 weeks. RESULTS: Major toxicities were leukocytopenia (CTC grade 3+4) in 8/16 and infections (CTC grade 3+4) in 7/16 patients. Six patients had dose-limiting toxicity which led to dose de-escalation from 100 to 70 mg/m2 in three patients. The maximum tolerated dose was 70 mg/m2. According to NCI-WG criteria, 9/16 patients (56%) responded to therapy, seven to doses

Autologous stem-cell transplantation restores the functional properties of CD14+CD16+ monocytes in patients with myeloma and lymphoma.

The CD14+CD16+ monocytes appear to be important to immune defense against infection, as these cells are very potent with respect to tumor necrosis factor (TNF) production, phagocytosis, and antigen presentation. Myeloablative high-dose chemotherapy (HDT) and subsequent autologous stem-cell transplantation (ASCT) are being used increasingly for therapy of hematological malignancies, but the pronounced immunosuppression renders the patients prone to infection. To determine the functional properties of CD14+CD16+ monocytes under these conditions, 15 patients with lymphoma or myeloma were examined. Before HDT, the ratio of CD14+CD16+ cells to the population of the classical CD14++ monocytes was 0.28 +/- 0.12; this ratio changed during the course of HDT and ASCT in favor of the CD14+CD16+ monocytes to a maximum of 12.4 +/- 7.8 (P<0.001) on day 3.5 +/- 1.6 after transplanation (Tx) and returned to 0.11 +/- 0.07 (P<0.001) after engraftment on day 11.3 +/- 2.2. Although the absolute number of classical CD14++ monocytes declined to less than 1/microl at the nadir, the number of CD14+CD16+monocytes fell from 29.7 +/- 9.8/microl to 4.5 +/- 3.0/microl at the nadir and increased to 13.8 +/- 9.8/microl at the day of discharge from the hospital. Flow cytometric analysis of phagocytosis of fluorescein isothiocyanate (FITC)-labeled Escherichia coli showed that 30 +/- 10% CD14+CD16+ monocytes of patients were FITC-positive before Tx, and at engrafment, the percentage of FITC-positive cells had doubled to 60 +/- 6% (healthy controls, 41+/-7%). When determining generation of reactive oxygen species after E. coli ingestion, the CD14+CD16+ monocytes showed a decreased response before Tx (32+/-12% positve cells), which increased to 53 +/- 24% after ASCT. The median fluorescence intensity of human leukocyte antigen (HLA)-DR expression on the CD14+CD16+ monocytes increased from 11 +/- 6 before Tx to 17 +/- 11 after Tx, and the production of TNF after lipopolysaccharide showed no remarkable difference (46+/-13 vs. 49+/-14 channels). At the same time, expression of TNF and of HLA-DR showed a dramatic decrease in the CD14++ monocytes. Taken together after stem-cell Tx, the function of the CD14++ monocytes is impaired, and the functional properties of CD14+CD16+ monocytes recover, indicating that these cells may be important for defense against infections post-ASCT.

Treosulfan-induced apoptosis in acute myeloid leukemia cells is accompanied by translocation of protein kinase C delta and enhanced by bryostatin-1.

OBJECTIVE: Acute myeloid leukemia (AML) still is fatal in the majority of patients. Therefore, we evaluated the antileukemic effect of the alkylating agent treosulfan in AML. MATERIALS AND METHODS: Chemosensitivity tests were performed in AML cell lines and primary cells from patients. Because protein kinase C (PKC) is known to play an integral role in the regulation of diverse cellular functions such as apoptosis, several PKC modulators were evaluated in conjunction with treosulfan. RESULTS: U937, THP-1, HL-60, TUR cells, and primary AML cells obtained from five consecutive patients displayed dose-dependent sensitivity to treosulfan. The LC(90) was approximately 100 microM, which is several fold below clinically achievable plasma levels. Cell death was associated with cellular events indicating apoptosis such as breakdown of the mitochondrial transmembrane potential, proteolytic activation of caspase-3, or appearance of a sub-G(1) DNA peak. Synergistic antileukemic effects were observed in all cell lines and patient samples tested using the PKC activators bryostatin-1 and 12-O-tetradecanoylphorbol-13-acetate (TPA), whereas the PKC inhibitor GF109203X substantially reduced apoptosis. Furthermore, long-term preincubation with bryostatin-1 or TPA, both of which are known to down-regulate PKC protein levels, likewise inhibited treosulfan-induced apoptosis. Immunoblots revealed membrane translocation of PKC-delta, indicating activation of this enzyme upon treosulfan exposure. CONCLUSION: Our data provide evidence for a strong antileukemic effect of treosulfan in both cell lines and AML blasts from patients at concentrations below the plasma levels described at standard dose levels. Furthermore, the proapoptotic effect of treosulfan is mediated at least in part by activation of PKC isoforms and can be augmented by coincubation with bryostatin-1.

Granulocyte-colony stimulating factor response is superior to neutropenia duration in predicting the risk of infection after high-dose chemotherapy for myeloma and lymphoma.

The patient granulocyte-colony stimulating factor (G-CSF) response is represented by the leukocyte peak in the blood induced by a single dose of G-CSF after chemotherapy, and is correlated with subsequent neutropenic infection risk. General patterns for a meaningful risk group stratification, have not yet been determined. Two independent data sets including a total of 306 cases with myeloma or lymphoma and autologous blood stem cell transplant were available. An infection susceptibility curve plotted according to ranked G-CSF responses from a multicenter study reproduced and validated a curve from the previous single center. Two trend changes were seen within these curves at around 11,000 and 22,000 leukocytes/µL, which separated three groups with a high, medium and low risk of infection. While G-CSF response is related to the consecutive duration of neutropenia, it retains additional independent predictive information for infection risk (p<0.0001) and, more important, is a tool available before the onset of the critical period.

Fludarabine combination therapy for the treatment of chronic lymphocytic leukemia.

Fludarabine combination therapies have attained an increased popularity in the treatment of chronic lymphocytic leukemia (CLL). Among them, the combination of fludarabine/cyclophosphamide (FC) is by far the best regimen studied. Patients receiving FC at relapse show response rates (RRs) of 70%-94% with 11%-34% complete remission (CR) rates. In previously untreated patients with CLL, RRs of 64%-88% with 21%-46% CR rates were observed. The main side effects of FC are myelotoxicity and infections; most complications are reported as fever of unknown origin, infections of the upper respiratory tract, or herpes virus infection. There is probably a correlation between the higher dose of cyclophosphamide (> 750 mg/m2 per treatment course) and an increase in the number of severe infectious complications. Similar results were reported regarding the RRs and side effects of the combination of fludarabine/epirubicin. The triple combination of fludarabine/cyclophosphamide/mitoxantrone and fludarabine combinations with anti-CD20 (rituximab) or anti-CD52 (Campath-1H) antibody, might be even be more promising, since a relevant number of complete molecular remissions are achieved with these drugs. The precise role of fludarabine combinations within the overall treatment strategy remains to be determined. Our current recommendation is to use these combinations at relapse, while their use in first-line therapy should be investigated in clinical protocols. It remains to be shown whether patients with CLL achieve improved overall survival with these combination chemotherapies.

Bendamustine induces G2 cell cycle arrest and apoptosis in myeloma cells: the role of ATM-Chk2-Cdc25A and ATM-p53-p21-pathways.

PURPOSE: Multiple myeloma is a fatal hematological disease caused by malignant transformation of plasma cells. Bendamustine has been proven to be a potent alternative to melphalan in phase 3 studies, yet its molecular mode of action is still poorly understood. METHODS: The four-myeloma cell lines NCI-H929, OPM-2, RPMI-8226, and U266 were cultured in vitro. Apoptosis was measured by flow cytometry after annexin V FITC and propidium iodide staining. Cell cycle distribution of cells was determined by DNA staining with propidium iodide. Intracellular levels of (phosphorylated) proteins were determined by western blot. RESULTS: We show that bendamustine induces apoptosis with an IC50 of 35-65 mug/ml and with cleavage of caspase 3. Incubation with 10-30 mug/ml results in G2 cell cycle arrest in all four-cell lines. The primary DNA-damage signaling kinases ATM and Chk2, but not ATR and Chk1, are activated. The Chk2 substrate Cdc25A phosphatase is degraded and Cdc2 is inhibited by inhibitory phosphorylation of Tyr15 accompanied by increased cyclin B levels. Additionally, p53 activation occurs as phosphorylation of Ser15, the phosphorylation site for ATM. p53 promotes Cdc2 inhibition by upregulation of p21. Targeting of p38 MAPK by the selective inhibitor SB202190 significantly increases bendamustine induced apoptosis. Additionally, SB202190 completely abrogates G2 cell cycle arrest. CONCLUSION: Bendamustine induces ATM-Chk2-Cdc2-mediated G2 arrest and p53 mediated apoptosis. Inhibition of p38 MAPK augments apoptosis and abrogates G2 arrest and can be considered as a new therapeutic strategy in combination with bendamustine.

Selective induction of apoptosis in leukemic B-lymphoid cells by a CD19-specific TRAIL fusion protein.

Although the treatment outcome of lymphoid malignancies has improved in recent years by the introduction of transplantation and antibody-based therapeutics, relapse remains a major problem. Therefore, new therapeutic options are urgently needed. One promising approach is the selective activation of apoptosis in tumor cells by the tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). This study investigated the pro-apoptotic potential of a novel TRAIL fusion protein designated scFvCD19:sTRAIL, consisting of a CD19-specific single-chain Fv antibody fragment (scFv) fused to the soluble extracellular domain of TRAIL (sTRAIL). Potent apoptosis was induced by scFvCD19:sTRAIL in several CD19-positive tumor cell lines, whereas normal blood cells remained unaffected. In mixed culture experiments, selective binding of scFvCD19:sTRAIL to CD19-positive cells resulted in strong induction of apoptosis in CD19-negative bystander tumor cells. Simultaneous treatment of CD19-positive cell lines with scFvCD19:sTRAIL and valproic acid (VPA) or Cyclosporin A induced strongly synergistic apoptosis. Treatment of patient-derived acute B-lymphoblastic leukemia (B-ALL) and chronic B-lymphocytic leukemia (B-CLL) cells resulted in strong tumoricidal activity that was further enhanced by combination with VPA. In addition, scFvCD19:sTRAIL prevented engraftment of human Nalm-6 cells in xenotransplanted NOD/Scid mice. The pre-clinical data presented here warrant further investigation of scFvCD19:sTRAIL as a potential new therapeutic agent for CD19-positive B-lineage malignancies.

Activation of adenosine monophosphate activated protein kinase inhibits growth of multiple myeloma cells.

The role of adenosine monophosphate activated protein kinase (AMPK) in regulating multiple myeloma (MM) cell growth is not yet clear. In this study, we show that the AMPK activators 5-aminoimidazole-4-carboxamide riboside (AICAr) and D942 inhibit cell growth in MM cell lines. AICAr also induced an S-phase cell cycle arrest in all four tested cell lines and led to phosphorylation and thus activation of AMPK. Furthermore, the inhibition of a nucleoside transporter by nitrobenzyl-thio-9-beta-d-ribofuranosylpurine (NBTI), inhibition of the adenosine kinase by iodotubericidine and inhibition of AMPK by AMPKI Compound C reversed AICAr effects, indicating that the cellular effects of AICAr were mediated by AMPK. Activation of AMPK inhibited basal extracellular signal-regulated kinase (ERK), mammalian target of rapamycin (mTOR) and P70S6 kinase (P70S6K) as well as AKT phosphorylation, and blocked IL-6, IGF-1, and HS-5 stromal cell conditioned medium-induced increase of cell growth. Troglitazone, which has previously been shown to activate AMPK, similarly inhibited MM cell growth, activated AMPK, and decreased ERK and P70S6K phosphorylation. Our results suggest that activation of AMPK inhibits MM cell growth despite stimulation with IL-6, IGF-1, or HS-5 stromal cell conditioned medium and represents a potential new target in the therapy of MM.

First clinical experience with simvastatin to overcome drug resistance in refractory multiple myeloma.

In vitro statins overcome cell adhesion-mediated drug resistance at non-toxic concentrations that are achievable in humans by standard dose simvastatin. A pilot phase-II trial was initiated to determine feasibility and antimyeloma efficacy. In six myeloma patients refractory to two cycles of bortezomib or bendamustine simvastatin was concomitantly administered during further two cycles. The therapy was well tolerated without grade 3/4 toxicity. Intrapatient (cycles I/II vs. III/IV) and interpatient comparison (vs. ten patients without simvastatin) showed reduction of drug resistance by inhibition of HMG-CoA-reductase. In summary, this is the first phase II experience to study antimyeloma activity of statins in humans.

Inhibition of adenosine monophosphate-activated protein kinase induces apoptosis in multiple myeloma cells.

In this study, we show that adenosine monophosphate-activated protein kinase (AMPK) is expressed and activated in multiple myeloma cells. The inhibition of AMPK induced growth arrest and reduction of cell viability in the cell viability assay using the water-soluble tetrazolium salt 4-[3-(4-iodophenyl)-2-(4-nitrophenyl)-2H-5-tetrazolio]-1,3-benzene disulfonate (WST-1 assay). Induction of apoptosis was determined by annexin-V and propidium iodide staining. The prevention of apoptosis using the pancaspase inhibitor ZVAD-fmk and caspase-3 cleavage upon incubation with the AMPK inhibitor (AMPKI) is shown. Furthermore, incubation of myeloma cells with AMPKI resulted in the downregulation of pAMPK, Mcl-1 and Bcl-xL. Coincubation of AMPKI and melphalan led to a strong additional increase of apoptosis in myeloma cells. We conclude that AMPKI has a strong antimyeloma activity in vitro and represents a new targeted strategy in the treatment of multiple myeloma.