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.

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).

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.

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.

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.

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.

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.

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.

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.

Imatinib combined with mitoxantrone/etoposide and cytarabine is an effective induction therapy for patients with chronic myeloid leukemia in myeloid blast crisis.

BACKGROUND: Despite advances in drug therapy and allogeneic stem cell transplantation (allo-SCT), the prognosis of patients with chronic myeloid leukemia (CML) in blast crisis remains poor. Imatinib has demonstrated synergistic effects in vitro with mitoxantrone, etoposide, and cytarabine. METHODS: A Phase I/II trial was performed in patients with CML myeloid blast crisis. Patients were treated with imatinib + mitoxantrone/etoposide in four cohorts: mitoxantrone 10 mg/m(2)/day and etoposide 100 mg/m(2)/day for 2 or 3 consecutive days and imatinib 600 mg/day from Day 15 (cohorts 1 and 2) or from Day 1 (cohorts 3 and 4). After hematologic reconstitution after the cytopenic phase, cytarabine was given at a dose of 10 mg/m(2)/day in addition to imatinib as maintenance treatment. RESULTS: A total of 16 patients were available for analysis, median age 59 years (range, 37-74). All patients who received more intensive induction treatment (cohorts 3 and 4, n = 7) achieved a hematologic response (HR). In contrast, HR was achieved in only 6 of 9 patients treated in cohorts 1 and 2. The induction treatment was well tolerated. Six patients who achieved HR received an allo-SCT with myeloablative conditioning. The median survival in the transplant group was 16.2 months vs 4.7 months in the group with conventional treatment only (P = .067). CONCLUSIONS: The combination of mitoxantrone/etoposide and imatinib is well tolerated, with mild nonhematologic toxicity even in older patients. Eligible patients benefit from allo-SCT after response to the induction treatment.

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.

Synergistic antimyeloma effects of zoledronate and simvastatin.

Despite advances in the treatment of multiple myeloma, it remains an incurable disease because of primary and secondary drug resistance. Mevalonate pathway inhibitors like bisphosphonates and statins have antimyeloma activity in vitro at very high concentrations, which may probably not be reached in vivo. NCI-H929, OPM-2, U266 and RPMI-8226 myeloma cell lines were treated in the presence or absence of bone marrow stromal cells with simvastatin or zoledronate in combination with classical antimyeloma drugs like melphalan or bortezomib. Zoledronate did not show substantial antimyeloma activity at low and intermediate concentrations, whereas simvastatin potently induced apoptosis in myeloma cells without signs of primary, cell-adhesion-mediated drug resistance. Furthermore, sequential blockage of the mevalonate pathway by zoledronate and simvastatin demonstrated synergistic induction of apoptosis and reversal of cell-adhesion-mediated drug resistance. Our data provide a rationale for combining zoledronate and simvastatin with classical antimyeloma drugs.

A CD33-specific single-chain immunotoxin mediates potent apoptosis of cultured human myeloid leukaemia cells.

A novel single-chain immunotoxin was constructed by combining a CD33-specific single chain Fv (scFv) antibody fragment with an engineered variant of Pseudomonas exotoxin A (ETA). The variant toxin carries the KDEL peptide at its C-terminus, a cellular peptide mediating improved retrograde transport to the endoplasmic reticulum. The purified recombinant fusion protein induced potent apoptosis of the human myeloid cell lines U937, HL-60 and THP-1. Up to 98% of U937 cells were eliminated after treatment for 72 h with a single dose of 500 ng/ml (c. 7 nmol/l). Killing was antigen-specific and occurred by apoptosis. A control protein, consisting of a CD19-specific scFv antibody fragment fused to the ETA-KDEL toxin, failed to induce death of the CD19-negative cell lines U937, HL-60 and THP-1. The CD33-ETA toxin also mediated apoptosis of fresh patient-derived acute myeloid leukaemia cells from bone marrow and peripheral blood. The pronounced antigen-restricted cytotoxicity of the novel fusion protein makes it a candidate for further evaluation of its therapeutic potential.

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.

Fludarabine plus cyclophosphamide versus fludarabine alone in first-line therapy of younger patients with chronic lymphocytic leukemia.

Combination chemotherapy with fludarabine plus cyclophosphamide (FC) was compared with the standard regimen of fludarabine monotherapy in first-line treatment of younger patients with chronic lymphocytic leukemia (CLL). Between 1999 and 2003, a total of 375 patients younger than 66 years who predominantly had advanced CLL were randomly assigned to receive either fludarabine (25 mg/m(2) for 5 days intravenously, repeated every 28 days) or FC combination therapy (fludarabine 30 mg/m(2) plus cyclophosphamide 250 mg/m(2) for 3 days intravenously, repeated every 28 days). Both regimens were administered to a maximum of 6 courses. FC combination chemotherapy resulted in significantly higher complete remission rate (24%) and overall response rate (94%) compared with fludarabine alone (7% and 83%; P < .001 and P = .001). FC treatment also resulted in longer median progression-free survival (48 vs 20 months; P = .001) and longer treatment-free survival (37 vs 25 months; P < .001). Thus far, no difference in median overall survival has been observed. FC caused significantly more thrombocytopenia and leukocytopenia but did not increase the number of severe infections. In summary, first-line treatment with FC increases the response rates and the treatment-free interval in younger patients with advanced CLL.

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

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.