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Biomedical subjects

H M Lokhorst

Publications and source records attributed to H M Lokhorst.

At least 19 recordsLinked to original sources
PubMed2006

[Two patients with hypereosinophilic syndrome].

Persistent eosinophilia was diagnosed in a 19-year-old woman with general malaise, dyspnoea attacks, coughing and episodes of angioedema and associated swallowing problems, and in a 21-year-old man with visual problems, dyspnoea, fatigue, reduced appetite, weight loss and gastrointestinal problems. Both had hypereosinophilic syndrome (a rare disease) with organ damage. In both patients, fluorescence-in-situ-hybridisation (FISH) was negative for the fusion gene FIP1L1-PDGFRA (FIPI-like-1-platelet-derived growth factor receptor alpha). The female patient's disease did not respond to either oral corticosteroids or imatinib, but did respond to hydroxycarbamide. The male patient successively received prednisone, interferon alpha and hydroxycarbamide. His eosinophilia progressed nonetheless, but responded partially to imatinib. In addition, the patient underwent an allogenic non-myeloblative stem cell transplantation from his HLA-identical sister. In patients with persistent eosinophilia accompanied by organ damage or organ dysfunction, hypereosinophilic syndrome can be diagnosed providing all secondary causes of the eosinophilia have been ruled out. Complementary investigations should include cytogenetic and clonal analysis to rule out haemopoietic malignancy. Prednisone, hydroxycarbamide, interferon alpha and the promising imatinib are all treatment options.

Adult↗
PubMed2006

Prognostic factors for donor lymphocyte infusions following non-myeloablative allogeneic stem cell transplantation in multiple myeloma.

In this retrospective study, we evaluated donor lymphocyte infusions given for relapsed (n=48) or persistent (n=15) myeloma following non-myeloablative allogeneic stem cell transplantation (Allo-SCT). Twenty-four of 63 patients (38.1%) responded: 12 patients (19.0%) with a partial response (PR) and 12 patients (19.0%) with a complete response (CR). Overall survival after donor lymphocyte infusions (DLI) was 23.6 months (1.0-50.7+). Median overall survival for non-responding patients was 23.6 months and has not been reached for the patients responding to DLI. In responders, progression-free survival after DLI was 27.8 months (1.2-46.2+). Patients with a PR had a median progression-free survival of 7.0 months, whereas patients with a CR to DLI had a median progression-free survival of 27.8 months. Major toxicities were acute graft-versus-host disease (GVHD) (38.1%) and chronic GVHD (42.9%). Seven patients (11.1%) died from treatment-related mortality. The only significant prognostic factors for response to DLI were the occurrence of acute and chronic GVHD. There was a trend towards significance for time between transplantation and DLI, and response. Donor lymphocyte infusion following non-myeloablative Allo-SCT is a valuable strategy for relapsed or persistent disease.

Acute Disease↗
PubMed2005

Malignant transformation in polyneuropathy associated with monoclonal gammopathy.

OBJECTIVE: To assess the frequency of hematologic malignancies at diagnosis and to determine the incidence and predictors of malignant transformation during follow-up in patients with polyneuropathy associated with monoclonal gammopathy. METHODS: Potential predictors of malignant transformation from medical history, hematologic, neurologic, and laboratory examination performed each 6 months were evaluated by univariable and multivariable Cox proportional hazard analysis. RESULTS: Of 193 patients with polyneuropathy associated with monoclonal gammopathy, 17 patients had a hematologic malignancy at diagnosis. The incidence rate of malignant transformation in 176 patients without a malignancy at diagnosis was 2.7/100 patient years. Weight loss, progression of the polyneuropathy, unexplained fever or night sweats, and M-protein level were independent predictors. CONCLUSIONS: Since hematologic malignancies occur frequently in polyneuropathy associated with monoclonal gammopathy, the authors suggest that all patients should be screened at diagnosis and subsequently during follow-up if malignant transformation is suspected.

Aged↗
PubMed2005

[Indications for bone marrow biopsy in adults].

Bone marrow biopsies are more and more often part of the work-up of patients with haematological disorders. The most important reason for this is the fact that a biopsy supplies important additional information compared to an aspirate alone. Biopsies are superior for the assessment of the bone marrow architecture, the vascularisation, the cellularity, the localisation and the extent of infiltrates and the degree of fibrosis. In addition, biopsy is a good way to evaluate the effects of therapy in the course of the disease. As is the case with aspirates, examination of a biopsy alone is usually sufficient for a correct diagnosis. However, a combination of both techniques makes possible an optimal assessment of the nature and extent of the disease process in the often very serious haematological conditions that we are dealing with here.

Biopsy, Needle↗
PubMed2005

Growth factors and antiapoptotic signaling pathways in multiple myeloma.

Failure of myeloma cells to undergo apoptosis plays an important role in the accumulation of myeloma cells within the bone marrow (BM). Moreover, inhibition of drug-induced apoptosis has been indicated as a major contributor of drug resistance in myeloma. The BM microenvironment promotes survival and blocks the apoptotic effects of various cytotoxic agents through the production of cytokines as well as through direct physical interactions. Several antiapoptotic proteins and antiapoptotic signaling cascades have been identified that contribute to the antiapoptotic phenotype of the myeloma cell. In this review, we discuss mechanisms that result in enhanced survival and drug resistance of myeloma cells. Insight into these mechanisms is essential to make progress in the therapy of myeloma.

Apoptosis↗
PubMed2004

A cost-utility analysis comparing intensive chemotherapy alone to intensive chemotherapy followed by myeloablative chemotherapy with autologous stem-cell rescue in newly diagnosed patients with stage II/III multiple myeloma; a prospective randomised phase III study.

A prospective randomised phase III study in patients < or =65 years old with previously untreated multiple myeloma (MM), intensive chemotherapy followed by myeloablative chemotherapy and autologous stem-cell rescue was compared with intensive chemotherapy alone. This economic evaluation was based on detailed data from patient charts and hospital information systems. In the intention-to-treat analysis, mean total treatment and follow-up costs of the myeloablative treatment arm were 81,643 euros compared to 68,802 euros for the chemotherapy arm (P=0.09). Costs per quality-adjusted life year were 51,357 euros versus 37,328 euros. In the clinical study, no significant differences were found in overall survival after a median follow-up of 33 months from randomisation. Intensive chemotherapy is regarded as standard therapy for younger patients with previously untreated MM. Cost-effectiveness of myeloma therapy after 3 years of follow up seems not to be favoured by myeloablative treatment with autologous stem-cell rescue.

Adult↗
PubMed2004

G3139, a Bcl-2 antisense oligodeoxynucleotide, induces clinical responses in VAD refractory myeloma.

Expression of Bcl-2 in multiple myeloma is associated with resistance to chemotherapeutic drugs. Conversely, suppression of Bcl-2 enhanced the chemosensitivity of myeloma cells in vitro. G3139 is an antisense oligodeoxynucleotide targeted to the first six codons of the Bcl-2 mRNA open reading frame. In this study, G3139 was delivered as a continuous intravenous infusion for 7 days at a fixed dose of 7 mg/kg/day in combination with VAD (vincristine, adriamycin, and dexamethasone) chemotherapy. In total, 10 heavily pretreated patients with refractory myeloma participated in this trial, including eight patients with VAD refractory disease. The combination of G3139 and VAD was feasible and well tolerated. Seven patients (70%) responded including four patients (40%) with a partial response and three patients (30%) with a minor response. Median progression-free survival was 6 months (range, 2-7+ months) and median overall survival has not been reached. G3139 downregulated Bcl-2 protein levels in peripheral blood circulating myeloma cells, B cells, T cells, and monocytes. These results indicate that G3139 may overcome classical resistance and restore sensitivity of myeloma tumor cells to VAD chemotherapy.

Adult↗
PubMed2004

Low incidence of infectious complications after nonmyeloablative compared with myeloablative allogeneic stem cell transplantation.

Allogeneic stem cell transplantation (SCT) using a myeloablative (MA) conditioning regimen is limited to relatively young patients because of increased transplant-related mortality in elderly patients. Nonmyeloablative (NMA) conditioning regimens have been developed aiming to reduce transplant mortality. In this study, we set out to evaluate the post-transplant occurrence of infectious complications in recipients of grafts from human leukocyte antigen (HLA)-identical sibling donors treated with either NMA or MA conditioning regimens. Data of 78 consecutively treated patients were analyzed. An NMA conditioning regimen was used in 40 patients and an MA regimen in 38 patients. A significantly lower rate of episodes of febrile neutropenia (0% vs. 34%, P<0.01) and post-transplant Epstein-Barr virus reactivations (0% vs. 18%, P<0.05) was found in SCT recipients treated with an NMA conditioning regimen compared with an MA conditioning regimen. Furthermore, fewer invasive fungal infections (2% vs. 12%, not significant) were diagnosed in the NMA group. The incidence of cytomegalovirus (CMV) reactivations and bacterial infections was low in both groups (CMV reactivations: 13% in both groups; bacterial infections: 10% in the NMA group vs. 8% in the MA group), while CMV disease developed in only 1 patient. Overall, compared to our MA regimen, we found a very low rate of infectious complications after NMA SCT.

Adult↗
PubMed2003

Chemosensitization of myeloma plasma cells by an antisense-mediated downregulation of Bcl-2 protein.

An antisense oligodeoxynucleotide (ODN) complementary to the first six codons of the Bcl-2 mRNA, G3139 (oblimersen sodium; Genasense), has been shown to downregulate Bcl-2 and produce responses in a variety of malignancies including drug-resistant lymphoma. Incubation of ex vivo purified plasma cells from patients with multiple myeloma (MM) with carboxyfluorescein (FAM)-labeled antisense ODNs resulted in a time- and dose-dependent uptake in the cytoplasm and nucleus. No major differences in uptake of Bcl-2 antisense ODNs were observed among patients' samples. Incubation of purified myeloma plasma cells with G3139, but not solvent or reverse polarity control ODNs, resulted in a reduction (>75%) of Bcl-2 mRNA levels after 2 and 4 days, as measured by Real-Time PCR. Treatment with G3139 led to a sequence-specific reduction of Bcl-2 protein levels within 4 days of exposure in 10 out of 11 clinical samples from patients with chemosensitive and multidrug-resistant disease, without significant reduction of alpha-Actin, Bax, Bcl-XL, or Mcl-1 proteins. This resulted in a significantly enhanced sensitivity of the myeloma tumor cells to dexamethasone or doxorubicin-induced apoptosis. G3139 can consistently enter myeloma cells, downregulate the expression of Bcl-2, and enhance the efficacy of myeloma therapy. These data support further clinical evaluation of G3139 therapy in multiple myeloma.

Aged↗
PubMed2003

The hepatocyte growth factor/Met pathway controls proliferation and apoptosis in multiple myeloma.

The evolution of multiple myeloma (MM) depends on complex signals from the bone marrow (BM) microenvironment, supporting the proliferation and survival of malignant plasma cells. An interesting candidate signal is hepatocyte growth factor/scatter factor (HGF), since its receptor Met is expressed on MM cells, while HGF is produced by BM stromal cells and by some MM cell lines, enabling para- or autocrine interaction. To explore this hypothesis, we studied the biological effects of HGF stimulation on MM cell lines and on primary MMs. We observed that Met is expressed by the majority of MM cell lines and by approximately half of the primary plasma cell neoplasms tested. Stimulation of MM cells with HGF led to the activation of the RAS/mitogen-activated protein kinase and phosphatidylinositol 3-kinase/protein kinase B (PI3K/PKB) pathways, signaling routes that have been implicated in the regulation of cell proliferation and survival. Indeed, functional studies demonstrated that HGF has strong proliferative and anti-apoptotic effects on both MM cell lines and primary MM cells. Furthermore, by applying specific signal-transduction inhibitors, we demonstrated that MEK is required for HGF-induced proliferation, whereas activation of PI3K is required for both HGF-induced proliferation and for rescue of MM cells from apoptosis. Taken together, our data indicate that HGF is a potent myeloma growth and survival factor and suggest that the HGF/Met pathway is a potential therapeutic target in MM.

Aged↗
PubMed2003

Antigens shared by malignant plasma cells and normal B cells may be involved in graft versus myeloma.

Cytotoxic T cells play an important role in graft-versus-host-disease (GvHD) and graft-versus-leukaemia/myeloma, which may occur in patients treated with an allogeneic stem cell transplantation (ASCT). Here, we describe the selection of a myeloma reactive CD4+ cytotoxic T cell-line (CTL) and two CD4+ clones from this CTL. The CTL was generated from the blood from a patient with multiple myeloma (MM) with graft versus myeloma/GvHD, following an ASCT. The CTL was stimulated using irradiated peripheral blood mononuclear cells and EBV transformed B cells from the myeloma patient (EBVp), both of which were obtained prior to ASCT. Both the CTL and the two T cell clones specifically lysed EBVp and secreted IFN-gamma after coculture with EBVp and autologous myeloma tumour cells in a class II restricted fashion. These results show that myeloma tumour cells and autologous B cells present a common polymorphic peptide that functions as a target for graft derived cytotoxic T cells. Identification of these proteins will give insight into the relationship between graft versus myeloma (GvM) and GvHD and may provide immunotherapeutical targets in the treatment of MM.

Antigens, Surface↗
PubMed2003

Extremely high levels of von Willebrand factor antigen and of procoagulant factor VIII found in multiple myeloma patients are associated with activity status but not with thalidomide treatment.

Venous thromboembolism (VTE) is a major complication in patients with multiple myeloma (MM) during treatment with thalidomide combined with chemotherapy and/or dexamethasone. The pathophysiology is not clear. We performed a cross-sectional study in 20 MM patients who were treated with thalidomide for refractory/relapsed disease. Seven patients (35%) experienced an episode of VTE. Plasma samples were analyzed for known risk factors for VTE and compared with those from 30 MM patients without thalidomide treatment. The patients groups differed in their baseline characteristics in activity status only. Extremely high levels of factor VIII-coagulant activity (FVIII:C, mean 352%) and von Willebrand factor antigen (VWF-Ag, 374%) were found in all patients using thalidomide. All other prothrombotic risk factors were normal. In patients with VTE, VWF-Ag but not FVIII:C, levels were significantly higher as compared with patients without VTE. Patients without thalidomide treatment had significantly lower levels of both coagulation factors but the difference was only due to difference in activity status. High FVIII:C/VWF-Ag levels are found in patients with active MM and this is probably a reflection of increased bone marrow angiogenesis in MM. These prothrombogenic circumstances could contribute to the high incidence of VTE during treatment with thalidomide in combination with dexamethasone/chemotherapy.

Aged↗
PubMed2002

[Thalidomide in the treatment of refractory multiple myeloma: a Dutch study of 72 patients: an antitumor effect in 45%].

OBJECTIVE: To determine the efficacy and side effects of thalidomide in the treatment of refractory multiple myeloma. DESIGN: Retrospective, descriptive. METHOD: Data were obtained by means of case research on patients with refractory multiple myeloma who were treated with thalidomide at four regional hematological centres in the period from 1 May 1999 to 31 May 2001. The patients had previously been treated with one, two or three schedules of chemotherapy. The starting dose of thalidomide was 200 mg per day and the dose was increased gradually to a maximum of 800 mg per day depending on the tolerance. RESULTS: The 72 patients included 43 men and 29 women with an average age of 62 years (range: 38-82 years). The median follow-up was 13 months (range: 2-25). Thalidomide as a single agent was prescribed for 64 patients, of whom 29 (45%) responded; a complete response was achieved in 3 patients, a partial response in 18, and a minor response in 8. In 4 of 11 patients with an extramedullary plasmacytoma a decrease in size was observed. The median duration of the response was 9 months (range: from 2 till > 24). The median overall survival from the start of thalidomide treatment was 9 months. Thalidomide plus dexamethasone was given to 9 patients who did not respond to thalidomide alone, and in 6 of them a reduction of M-protein was then observed. The most frequent adverse effects were constipation, drowsiness, somnolence, dizziness, venous thrombosis and polyneuropathy. Doses of up to 400 mg per day were generally well tolerated. CONCLUSION: Thalidomide has antitumour activity in refractory multiple myeloma.

Adult↗
PubMed2002

CD44 variant isoforms are involved in plasma cell adhesion to bone marrow stromal cells.

Expression of CD44v9-containing isoforms (CD44v9) on myeloma plasma cells correlates with unfavorable prognosis, suggesting that CD44 variant molecules are involved in the disease process. In this study, the presence of CD44v on B cell lines from different stages of development was analyzed by flow cytometry and a role in adhesion to stromal cells from different tissues was evaluated in in vitro binding assays. CD44v3, v6 and v9 isoforms were exclusively expressed on plasma cell lines and CD44v9 expression correlated with IL-6-dependent plasma cell growth. Binding studies using CD44 isoform- specific reagents showed that CD44v6 and CD44v9 were involved in binding to bone marrow stromal cells, but not to in vitro synthesized ECM or hyaluronic acid. CD44v9-mediated plasma cell binding resulted in a significant induction of IL-6 secretion by bone marrow stromal cells. Large differences in quantitative plasma cell binding to stromal cells from different tissues were observed. These, however, could not be related to a differential use of CD44v in these binding processes. The role of CD44v9 in adhesion induced IL-6 secretion and its preferential expression on IL-6-dependent plasma cell lines may explain the previously observed correlation between CD44v9 expression and adverse prognosis in multiple myeloma.

Adult↗