Immunomodulatory derivative of thalidomide (IMiD CC-4047) induces a shift in lineage commitment by suppressing erythropoiesis and promoting myelopoiesis

Immunomodulatory derivative (IMiD) CC-4047, a new analog of thalidomide, directly inhibits growth of B-cell malignancies in vivo and in vitro and exhibits stronger antiangiogenic activity than thalidomide. However, there is little information on whether CC-4047 affects normal hematopoiesis. Here we investigated the effect of CC-4047 on lineage commitment and differentiation of hematopoietic stem cells. We found that CC-4047 effectively inhibits erythroid cell colony formation from CD34+ cells and increases the frequency of myeloid colonies. We also demonstrate that development of both erythropoietin-independent and erythropoietin-dependent red cell progenitors was strongly inhibited by CC-4047, while terminal red cell differentiation was unaffected. DNA microarray analysis revealed that red cell transcription factors, including GATA-1, GATA-2, erythroid Kruppel-like factor (EKLF), and growth factor independence-1B (Gfi-1b), were down-regulated in CC-4047-treated CD34+ cells, while myeloid transcription factors such as CCAAT/enhancer binding protein-alpha (C/EBPalpha), C/EBPdelta, and C/EBPepsilon were induced. Analysis of cytokine secretion indicated that CC-4047 induced secretion of cytokines that enhance myelopoiesis and inhibit erythropoiesis. In conclusion, these data indicate that CC-4047 might directly influence lineage commitment of hematopoietic cells by increasing the propensity of stem and/or progenitor cells to undergo myeloid cell development and concomitantly inhibiting red cell development. Therefore, CC-4047 provides a valuable tool to study the mechanisms underlying lineage commitment.

Flt-3 ligand as adjuvant for DNA vaccination augments immune responses but does not skew TH1/TH2 polarization

Since transfection of dendritic cells (DC) plays a key role in DNA vaccination, in vivo expansion of DC might be a tool to increase vaccine efficacy. We asked whether Fms-like tyrosine kinase-3 ligand (Flt-3L), a growth factor for DC, can be used as an adjuvant for DNA vaccination. Beta-galactosidase (beta-gal) was used as a model antigen in C57BL/6 mice. Mice were immunized i.m. with DNA coding for beta-gal with or without additional injection of Flt-3L. In both cases, antigen-specific CD4+ and CD8+ T cells were detectable after vaccination. Compared with DNA alone, additional administration of Flt-3L led to a significant increase in the antigen-specific proliferative response. However, increased cytotoxicity by T cells was not observed. The cytokines secreted by splenocytes of immunized mice upon in vitro stimulation with antigen had a TH2 profile. Humoral responses against beta-gal preferentially consisted of IgG1 antibodies. Analysis of DC from Flt-3L-treated mice revealed an immature phenotype with low or absent expression levels of CD80, CD86 and CD40. We conclude that Flt-3L does not generally skew immune responses towards a TH1 type. More likely, factors determined by the antigen and/or the vaccination procedure itself are crucial for the resulting type of immune response. Flt-3L - under circumstances such as the one we have investigated - can also lead to suppression of TH1 T cell immunity, possibly by expansion of immature/unactivated DC.

Smac induces cytochrome c release and apoptosis independently from Bax/Bcl-x(L) in a strictly caspase-3-dependent manner in human carcinoma cells

The mitochondrial apoptosis pathway mediates cell death through the release of various pro-apoptotic factors including cytochrome c and Smac, the second mitochondrial activator of caspases, into the cytosol. Smac was shown previously to inhibit IAP proteins and to facilitate initiation of the caspase cascade upon cytochrome c release. To investigate Smac function during apoptosis and to explore Smac as an experimental cancer therapeutic, we constructed an expression system based on a single adenoviral vector containing Smac under control of the Tet-off system supplied in cis. Conditional expression of Smac induced apoptosis in human HCT116 and DU145 carcinoma cells regardless of the loss of Bax or overexpression of Bcl-x(L). Nevertheless, apoptosis induced by Smac was associated with cytochrome c release and breakdown of the mitochondrial membrane potential. This indicates that Smac acts independently of Bax and Bcl-x(L) during initiation of apoptosis and triggers a positive feedback loop that results in Bax/Bcl-x(L)-independent activation of mitochondria. In caspase-proficient cells, Smac-induced apoptosis could be inhibited partially by cell-permeable LEHD (caspase-9 inhibitor) and DEVD (caspase-3 inhibitor) peptides. Furthermore, loss of caspase-3 expression in MCF-7 cells carrying a caspase-3 null mutation completely abrogated the sensitivity for Smac-induced apoptotic or nonapoptotic, necrosis-like cell death, while re-expression of caspase-3 conferred sensitivity. Altogether, caspase-3 but not caspase-9 activation was necessary for execution of Smac-induced cell death. Notably, Smac did not induce caspase-9 processing in the absence of caspase-3. Thus, caspase-9 processing occurs secondary to caspase-3 activation during Smac-induced apoptosis. Altogether, Smac is capable of circumventing defects in mitochondrial apoptosis signaling such as loss of Bax or overexpression of Bcl-x(L) that are frequently observed in tumor cells resistant to anticancer therapy. Consequently, Smac appears to be a promising therapeutic target in anticancer treatment.

Trimethoprim-Sulfamethoxazole Exacerbates Posthypoxic Action Myoclonus in a Patient with Suspicion of Pneumocystis jiroveci Infection

We describe a 58-year-old patient with relapsing high-grade non-Hodgkin's lymphoma who exhibited exacerbation of posthypoxic action myoclonus during high-dose intravenous trimethoprim-sulfamethoxazole (TMP-SMX) treatment for highly suspicious Pneumocystis jiroveci pneumonia (PCP). Three months previously the patient had experienced a hypoxic insult caused by respiratory arrest due to an anaphylactic reaction to antibiotic therapy. He had developed posthypoxic action myoclonus (Lance-Adams syndrome), which was well controlled by oral treatment with piracetam. However, after TMP-SMX therapy (115 mg/kg daily) was started for suspicion of newly developed PCP, posthypoxic action myoclonus worsened dramatically resulting in complete disability. Anti-myoclonic therapy with increased doses of piracetam and valproic acid did not significantly improve his clinical condition. Only when TMPSMX doses were reduced (38 mg/kg daily) on day 12 did action myoclonus cease within 2 to 3 days. We suggest that TMP-SMX can exacerbate posthypoxic action myoclonus.

Jagged1-induced Notch signaling drives proliferation of multiple myeloma cells

Notch receptors expressed on hematopoietic stem cells interact with their ligands on bone marrow stromal cells and thereby control cell fate decisions and survival. We recently demonstrated that Notch signaling is involved in proliferation and survival of B cell-derived tumor cells of classic Hodgkin disease and described a novel mechanism for the oncogenic capacity of Notch. In this study we investigated whether Notch signaling is involved in the tight interactions between neoplastic plasma cells and their bone marrow microenvironment, which are essential for tumor cell growth in multiple myeloma (MM). Here we demonstrate that Notch receptors and their ligand Jagged1 are highly expressed in cultured and primary MM cells, whereas nonneoplastic counterparts show low to undetectable levels of Notch. Functional data indicate that ligand-induced Notch signaling is a growth factor for MM cells and suggest that these interactions contribute to myelomagenesis in vivo. (Blood. 2004;103:3511-3515)

c-FLIP mediates resistance of Hodgkin/Reed-Sternberg cells to death receptor-induced apoptosis

Resistance to death receptor–mediated apoptosis is supposed to be important for the deregulated growth of B cell lymphoma. Hodgkin/Reed-Sternberg (HRS) cells, the malignant cells of classical Hodgkin's lymphoma (cHL), resist CD95-induced apoptosis. Therefore, we analyzed death receptor signaling, in particular the CD95 pathway, in these cells. High level CD95 expression allowed a rapid formation of the death-inducing signaling complex (DISC) containing Fas-associated death domain–containing protein (FADD), caspase-8, caspase-10, and most importantly, cellular FADD-like interleukin 1β–converting enzyme-inhibitory protein (c-FLIP). The immunohistochemical analysis of the DISC members revealed a strong expression of CD95 and c-FLIP overexpression in 55 out of 59 cases of cHL. FADD overexpression was detectable in several cases. Triggering of the CD95 pathway in HRS cells is indicated by the presence of CD95L in cells surrounding them as well as confocal microscopy showing c-FLIP predominantly localized at the cell membrane. Elevated c-FLIP expression in HRS cells depends on nuclear factor (NF)-κB. Despite expression of other NF-κB–dependent antiapoptotic proteins, the selective down-regulation of c-FLIP by small interfering RNA oligoribonucleotides was sufficient to sensitize HRS cells to CD95 and tumor necrosis factor–related apoptosis-inducing ligand–induced apoptosis. Therefore, c-FLIP is a key regulator of death receptor resistance in HRS cells.

Downregulation of genes involved in DNA repair and differential expression of transcription regulators and phosphatases precede IgM-induced apoptosis in the Burkitt's lymphoma cell line BL60-2

Apoptosis of lymphocytes recognizing self-antigens is an essential mechanism to protect the organism against autoimmune diseases. Programmed cell death of susceptible B cells occurs in response to surface IgM cross-linking mediated by self-antigens. This effect can be mimicked in the Burkitt's lymphoma line BL60-2 by addition of anti-IgM antibodies. In order to identify genes with differential expression in response to the apoptotic stimulus, total RNA prepared from BL60-2 cells before and at different points in time after IgM cross-linking was used for Atlas arrays, high-density oligonucleotide microarrays (GeneChip arrays, Affymetrix) and in RNase protection assays (RPA). One of our major observations was the downregulation of six genes involved in the ligation of DNA strand breaks, like DNA ligases and DNA-PK, indicating a shutdown of DNA repair mechanisms in apoptotic cells. In addition, we found changes on mRNA level for several transcription regulators, including early growth response genes 1 and 2, TAFII30 and topoisomerase I. Furthermore, we show accumulation of mRNA for the phosphatases CD45 and DUSP5 in anti-IgM stimulated BL60-2 cells. Our data provide a basis for further analysis of the differentially expressed genes and their roles in IgM-induced B cell death as well as in apoptosis in other cellular systems.

T cell recognition of bcr/abl in healthy donors and in patients with chronic myeloid leukaemia

In chronic myeloid leukaemia (CML), peptides from the fusion region of bcr3/abl2 are likely to play a role in anti-leukaemic T cell immunity. We investigated whether T cells that recognize bcr/abl fusion peptides could be detected in healthy donors and CML patients. T cell responses against bcr3/abl2 fusion peptides were analysed by gamma-interferon enzyme-linked immunospot assays after prestimulation of peripheral blood mononuclear cells in the presence of anti-CD3-antibodies and interleukin-2. Our results suggest that the T cell repertoire contains bcr3/abl2-reactive T cells in CML patients who are in cytogenetic remission, but also in some healthy individuals.

Differential Emu enhancer activity and expression of BOB.1/OBF.1, Oct2, PU.1, and immunoglobulin in reactive B-cell populations, B-cell non-Hodgkin lymphomas, and Hodgkin lymphomas

It has previously been demonstrated that in cultured and in situ tumour cells of classical Hodgkin lymphoma (cHL), the immunoglobulin (Ig) promoter is inactive and its transcription factors Oct2 and/or BOB.1/OBF.1 are down-regulated. In this study, the analysis of these transcription factors has been extended to a broad spectrum of B-cell malignancies and the findings have been related to the situation in normal B-cells of various differentiation stages and to the expression of Ig. Furthermore, an additional Ig transcription factor, PU.1, recently described to be absent from cHL, and a further regulatory element of the Ig gene, the intronic Emu enhancer, have been studied. BOB.1/OBF.1 and Oct2 were present in all B-cells expressing Ig, whereas PU.1 proved to be absent from late B-cell differentiation stages and from a subset of germinal centre B-cells. Interestingly, there were several normal (eg germinal centre centroblasts and monocytoid B-cells) and malignant B-cell populations (eg a proportion of diffuse large B-cell lymphomas, DLBCLs) that were Ig-negative, despite their BOB.1/OBF.1 and Oct2 expression. This study further shows that absence of PU.1 alone, as well as inactivation of the intronic Emu enhancer, is not sufficient to down-regulate Ig transcription. Taken together, the simultaneous absence of PU.1, Oct2, and/or BOB.1/OBF.1 is unique to Hodgkin and Reed-Sternberg (HRS) cells and cannot be detected in normal B-cell subsets or B-cell non-Hodgkin lymphomas (B-NHLs). This supports the concept that the down-regulation of Ig in cHL does not reflect a physiological situation, but a defect probably closely linked to the pathogenesis of cHL.

Cellular senescence in cancer treatment: friend or foe?

Damage to DNA, the prime target of anticancer therapy, triggers programmed cellular responses. In addition to apoptosis, therapy-mediated premature senescence has been identified as another drug-responsive program that impacts the outcome of cancer therapy. Here, we discuss whether induction of senescence is a beneficial or, rather, a detrimental consequence of the therapeutic intervention.

A novel recombinant bispecific single-chain antibody, bscWue-1 × CD3, induces T-cell-mediated cytotoxicity towards human multiple myeloma cells

The development of antibody-based strategies for the treatment of multiple myeloma (MM) has been hampered so far by the fact that suitable plasma cell-specific surface antigens have been missing. However, recently a novel monoclonal antibody, designated Wue-1, has been generated that specifically recognizes normal and malignant human plasma cells. Therefore, Wue-1 is an interesting and promising candidate to develop novel immunotherapeutic strategies for the treatment of MM. One variant for an antibody-based strategy is the bispecific antibody approach. Recombinant bispecific single-chain (bsc) antibodies are especially interesting candidates because they show exceptional biological properties. We have generated a novel MM-directed recombinant bsc antibody, bscWue-1 x CD3, and analyzed the biological properties of this antibody using the MM cell line NCI-H929 and primary cells from the bone marrow of patients with MM. We were able to show that bscWue-1 x CD3 induces efficient and selective T-cell-mediated cell death of NCI-H929 cells and primary myeloma cells in nine out of 11 cases. The bscWue-1 x CD3 Ab is efficacious even at low E:T ratios, and with or without additional T-cell pre- or costimulation. Target cell lyses were specific for Wue-1 antigen-positive cells and could be blocked by the Wue-1 monoclonal antibody.

Filgrastim-induced stem cell mobilization in chronic myeloid leukaemia patients during imatinib therapy: safety, feasibility and evidence for an efficient in vivo purging

Therapy with imatinib mesylate is limited by cellular resistance in chronic myeloid leukaemia (CML). Further, the limited availability of matching stem cell donors or an unfavourable risk profile for allogeneic stem cell transplantation (SCT) reduces the number of therapeutic options in a number of patients. To assess the possibility of stem cell mobilization (SCM) during imatinib therapy we performed granulocyte colony-stimulating factor (filgrastim)-induced SCM and subsequent aphaeresis in 15 chronic phase and three accelerated phase CML patients. Aphaeresis was successful in 13 patients (72%) (> or =2.0 x 10(6) CD34+ cells/kg body weight) and five (28%) harvests could be obtained, which were negative for BCR/ABL mRNA as assessed by nested-reverse transcription polymerase chain reaction (RT-PCR). All harvests, except one, were negative after first round RT-PCR, implicating a low level of CML cell contamination. There was no significant change in peripheral BCR/ABL transcript load after SCM as assessed by quantitative real-time RT-PCR. Fifteen patients remained stable in complete cytogenetic remission (CCR) during a median observation period of 9.3 months. One patient achieved a molecular remission shortly after SCM. Another patient who exhibited rising BCR/ABL mRNA levels before SCM achieved CCR after autologous SCT with the generated harvest. One patient with a Philadelphia chromosome-negative, BCR/ABL-positive CML showed a cytogenetic relapse 6 months after SCM. We conclude that filgrastim-induced CD34+ cell aphaeresis under simultaneous imatinib medication is safe and feasible in CML patients. Additionally, we found evidence that this procedure could generate stem cell harvests that exhibit non-detectable levels of BCR/ABL mRNA.

Induction of apoptosis by enediyne antibiotic calicheamicin ϑII proceeds through a caspase-mediated mitochondrial amplification loop in an entirely Bax-dependent manner

Calicheamicin thetaII is a member of the enediyne class of antitumor antibiotics that bind to DNA and induce apoptosis. These compounds differ, however, from conventional anticancer drugs as they bind in a sequence-specific manner noncovalently to DNA and cause sequence-selective oxidation of deoxyriboses and bending of the DNA helix. Calicheamicin is clinically employed as immunoconjugate to antibodies directed against, for example, CD33 in the case of gemtuzumab ozogamicin. Here, we show by the use of the unconjugated drug that calicheamicin-induced apoptosis is independent from death-receptor/FADD-mediated signals. Moreover, calicheamicin triggers apoptosis in a p53-independent manner as shown by the use of p53 knockout cells. Cell death proceeds via activation of mitochondrial permeability transition, cytochrome c release and activation of caspase-9 and -3. The overexpression of Bcl-x(L) or Bcl-2 strongly inhibited calicheamicin-induced apoptosis. Knockout of Bax abrogated cell death after calicheamicin treatment. Thus, the activation of mitochondria and execution of cell death occur through a fully Bax-dependent mechanism. Interestingly, caspase inhibition by the pancaspase-inhibitor zVAD-fmk interfered with mitochondrial activation by calicheamicin. This places caspase activation upstream of the mitochondria and indicates that calicheamicin-triggered apoptosis is enhanced through death receptor-independent activation of the caspase cascade, that is, an amplification loop that is required for full activation of the mitochondrial pathway.

Pharmacokinetics and cellular uptake of imatinib and its main metabolite CGP74588

Despite the remarkable clinical response rates to imatinib in the treatment of bcr-abl leukemic patients, pharmacokinetic data on this relatively novel substance are needed to improve our understanding of the emergence of resistance, the interindividual variations of clinical response and the clinical and biologic relevance of its main metabolite N-desmethyl-imatinib. We present here pharmacokinetic data obtained with a newly designed HPLC approach in 97 patients with chronic myeloid leukemia or acute lymphatic leukemia (ALL) under treatment with imatinib that allowed us to calculate the AUC (39.5 microg.h/ml for an oral dose of 400 mg daily), the t(1/2) (18.2 h) and the peak concentration (1.92 micro/ml for an oral dose of 400 mg daily) of imatinib in plasma. In a subgroup of patients, the same parameters were analyzed for N-desmethyl-imatinib. We also provide data on the imatinib concentration in the cerebrospinal fluid (CSF) of ALL patients and demonstrate that oral administration of imatinib resulted only in a marginal flux across the blood-brain barrier. Finally, in an in vitro setting, we determined cellular concentrations of imatinib in HL-60 cells and showed an over-proportional uptake both in RPMI medium and in human plasma. Using an arithmetical approach combining all parameters obtained in imatinib-treated patients, we finally provide a conclusive approximation of basic pharmacokinetic data for both imatinib and its main metabolite N-desmethyl-imatinib.

Safety and efficacy of stem cell mobilization under imatinib therapy

In order to investigate the safety and efficacy of stem cell mobilization in chronic myeloid leukemia patients under imatinib therapy we treated 10 such patients with granulocyte colony-stimulating factor. We observed that none of the patients developed progressive disease under this treatment. Instead, sufficient CD34+ apheresis could be performed in 7 patients and, as assessed by nested reverse transcriptase polymerase chain reaction (RT-PCR), bcr/abl-negative stem cell products could be generated in 3 patients. Interestingly, in 3 other patients with bcr/abl-positivity in 1st round RT-PCR of peripheral leukocytes, bcr/abl transcripts in stem cell products could only be detected by nested RT-PCR.

Dynamic expression profile of p21WAF1/CIP1 and Ki-67 predicts survival in rectal carcinoma treated with preoperative radiochemotherapy

PURPOSE

We investigated p53 and its downstream effectors p21WAF1/CIP1, BAX, and hMSH2 as well as the proliferation marker Ki-67 (mki-67/MIB-1) in patients undergoing preoperative radiochemotherapy for rectal carcinoma to identify prognostic and predictive factors. The focus of this study was on the dynamics of these genetic markers in a longitudinal study-that is, before and after radiochemotherapy.

PATIENTS AND METHODS

Expression of p53, BAX, p21WAF1/CIP1, Ki-67, and hMSH2 was investigated by immunohistochemistry in pre- and posttherapeutic tumor samples in 66 patients. Tumor DNA was screened for p53 mutations by single-strand conformation polymorphism-polymerase chain reaction (SSCP-PCR). Paired tumor samples (pretherapy and posttherapy) were collected prospectively.

RESULTS

Patients with a decrease in p21 expression following radiochemotherapy had better disease-free survival (P =.03). Similarly, patients with an increase in proliferative activity as measured by increased Ki-67 expression posttherapy had better disease-free survival (P <.005). In addition, we observed a significantly better prognosis for patients with high hMSH2 expression. In contrast, pretherapeutic levels of p53, BAX, or p21 expression and p53 mutation had no prognostic value, indicating that the combination of radiotherapy and chemotherapy might override defects in these genes.

CONCLUSION

These findings are novel and support the clinical relevance of p21 in the suppression of both proliferation and apoptosis. Thus, the dynamic induction of p21WAF1/CIP1 was associated with a lower proliferative activity but an ultimately worse treatment outcome following neoadjuvant radiochemotherapy and tumor resection. Induction of p21, therefore, represents a novel resistance mechanism in rectal cancer undergoing preoperative radiochemotherapy.

Inactivating I kappa B epsilon mutations in Hodgkin/Reed-Sternberg cells

The pathogenesis of Hodgkin lymphoma (HL) is still unclear. Previous investigations have demonstrated constitutive nuclear activity of the transcription factor NF kappa B (NF-kappaB) in Hodgkin/Reed-Sternberg (HRS) cells as an important prerequisite in protecting these cells from apoptosis. As a molecular mechanism leading to constitutive NF-kappaB activity in HRS cells, mutations of the NF-kappaB inhibitor I kappa B alpha (IkappaBalpha) have recently been identified in classical (c) HL-derived cell lines in a patient with cHL. In the present study, the NF-kappaB inhibitor I kappa B epsilon (IkappaBepsilon) has been analysed for somatic mutations in the same group of six patients already studied for IkappaBalpha mutations, as well as in cHL-derived cell lines. In one cHL-derived cell line (L428), a hemizygous frame-shift mutation generating a pre-terminal stop codon resulting in a severely truncated protein was found. Moreover, in the HRS cells of one patient, a hemizygous mutation affecting the 5'-splicing site of intron 1 of the IkappaBepsilon gene was found. These results, in combination with recently described IkappaBalpha mutations, indicate that defective NF-kappaB inhibitors appear more frequent than previously thought and might explain the constitutive nuclear activity of NF-kappaB in a significant proportion of cHL cases.

Recombinant human erythropoietin, epoetin beta, in patients with relapsed lymphoma treated with aggressive sequential salvage chemotherapy--results of a randomized trial

The aim of the study was to investigate the effects of erythropoietin (epoetin beta) on red blood cell (RBC) transfusions, hemoglobin (Hb) levels, and quality of life (QOL) in patients with relapsed lymphoma treated with an aggressive sequential salvage chemotherapy (SSCT) regimen. Sixty patients with early or late relapsed Hodgkin's disease ( n=39) or first relapse of aggressive non-Hodgkin's lymphoma ( n=21) were randomized to receive epoetin beta 10,000 IE subcutaneously three times a week or no epoetin during salvage chemotherapy. Patients in both study arms received two cycles of DHAP (dexamethasone, high-dose cytarabine, cisplatin); patients in partial remission (PR) or complete remission (CR) then received cyclophosphamide, followed by peripheral blood stem cell (PBSC) harvest, methotrexate plus vincristine, and etoposide. The final myeloablative course was BEAM (carmustine, etoposide, cytarabine, and melphalan) followed by autologous stem cell support. The primary endpoint of the study was the number of RBC units needed during SSCT. In addition, Hb levels and QOL were measured. The mean number of RBC units given in the epoetin beta arm was 4.5 compared to 8.3 in the control arm ( P=0.0134). The mean Hb levels during therapy were 10.4 g/dl in the epoetin beta arm and 9.7 g/dl in the control ( P=0.018). From baseline until BEAM therapy QOL (EORTC QLQ C30) and fatigue (MFI) assessment showed little QOL worsening or stable levels in both arms with a steeper increase of fatigue levels in the control group. Patients with relapsed lymphoma undergoing aggressive chemotherapy and stem cell support benefited from epoetin beta therapy, with a decrease of RBC transfusion requirements and lower rise of fatigue levels.