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M Zühlsdorf

Publications and source records attributed to M Zühlsdorf.

At least 19 recordsLinked to original sources
PubMed2002

[Progressive multifocal leukoencephalopathy (PML) in chronic lymphatic leukemia (CLL). Review of the literature and case report].

Progressive multifocal leukoencephalopathy (PML) is an infectious disease of the central nervous system caused by the JC virus. Progressive multifocal leukoencephalopathy represents a reactivation of the JC virus after long-standing immunosuppression. Also, PML plays an important role as an opportunistic infection in patients with AIDS. The average time of survival in patients with PML in combination with chronic lymphatic leukemia (CLL) (n = 17 in the literature) is 4.3 months, and therapeutic options are not established. We report the case of a patient with CLL and PML. Clinical symptoms are slight hemiparesis of the right side, mainly appearing as a disturbance of motor function. In MRI, a typical subcortical lesion was shown, and JC virus DNA was positive in the CSF by PCR. Because of first positive results in treatment of PML in patients with AIDS, therapy with cidofovir was started. After treatment for 16 months, symptoms are stable, the PML-induced lesions in MRI are in regression, and JC virus DNA is not detectable in the CSF.

Antiviral Agents↗
PubMed2002

Early tandem high-dose ifosfamide, carboplatin, etoposide therapy with stem cell rescue for small-cell lung cancer: brief report on the results of a phase-I/II trial.

OBJECTIVE: High-dose therapy (HDT) for small-cell lung cancer is experimental. Late intensification HDT for chemosensitive disease can increase the number and quality of remissions and prolong relapse-free survival, but has not yet shown impact on overall survival. This is possibly due to resistant residual disease. To overcome the development of resistance, we have tested early intensification tandem HDT. METHODS: We performed a phase-I/II trial using 1 conventional cycle of ifosfamide, carboplatin, etoposide (ICE) plus granulocyte colony-stimulating factor for stem cell recruitment followed by 2 cycles of high-dose ICE with rescue by CD34+ cell-enriched peripheral blood mononuclear cells. Dose escalation was performed for the 2 high-dose ICE cycles. Radiotherapy for limited disease was according to standard protocols. RESULTS: 17 patients were entered: 2 female patients; 15 male patients; median age 53 (range 36-65) years; 2 patients with limited disease, and 15 patients with extensive disease. We treated 4 patients at dose level 1, 11 patients at level 2, and 2 patients at level 3. The maximum tolerable dose was at level 2 with neuropathy being dose-limiting. Overall, toxicity was < or = grade 2 for all patients up to dose level 2 with hematotoxicity being grade 4 for all patients. There were 15 partial remissions (88%), 1 no change (6%), and 1 progressive disease (6%). Median time to progression was 7.9 months. Overall survival was 12.9 months (median). CONCLUSIONS: Early intensification with this protocol is feasible. Although a comparatively good response rate and median time to progression have been observed in this group dominated by patients with extensive disease, overall survival is short and no substantial long-term survival was found.

Adult↗
PubMed2001

Anaphylactic reactions to aprotinin reexposure in cardiac surgery: relation to antiaprotinin immunoglobulin G and E antibodies.

BACKGROUND: Aprotinin, a serine proteinase inhibitor, reduces bleeding during cardiac surgery. As aprotinin is derived from bovine lung, it has antigenic properties. This investigation examined the incidence of anaphylactic reactions in patients reexposed to aprotinin and the relation to preformed antiaprotinin immunoglobulin (Ig)G and IgE antibodies. METHODS: This prospective observational study conducted at five centers in Germany evaluated patients undergoing repeat cardiac surgery reexposed to aprotinin between 1995 and 1996. Antiaprotinin IgG and IgE antibody measurements, using a noncommercial enzyme-linked immunosorbent assay and an immunofluorescence assay, respectively, were performed preoperatively and postoperatively. An anaphylactic reaction was defined as major changes from baseline within 10 min of aprotinin administration of systolic pressure 20% or greater, heart rate 20% or greater, inspiratory pressure greater than 5 cm H2O, or a skin reaction. RESULTS: In 121 cases (71 adults, 46 children), a mean aprotinin reexposure interval of 1,654 days (range, 16-7,136 days) was observed. Preoperative antiaprotinin IgG (optical density ratio > 3) and IgE antibodies (radioallergosorbent test [RAST] score < 3) were detected in 18 and 9 patients, respectively. High concentrations of each (IgG, optical density ratio > 10; IgE, RAST score > or = 3) were detected in five patients. Three patients (2.5%; 95% confidence interval, 0.51-7.1%) experienced an anaphylactic reaction after aprotinin exposure, followed by full recovery; these patients had reexposure intervals less than 6 months (22, 25, and 25 days) and the highest preoperative IgG concentrations of all patients (P < 0.05). Assay sensitivity was 100%, as no anaphylactic reactions occurred in IgG-negative patients (95% confidence interval, 0.0-3.1%); assay specificity was 98%. Preoperative IgE measurements were quantifiable in two of three reactive patients and in three nonreacting patients. CONCLUSIONS: Quantitative detection of antiaprotinin IgE and IgG lacks specificity for predictive purposes; however, quantitation of antiaprotinin IgG may identify patients at risk for developing an anaphylactic reaction to aprotinin reexposure.

Adolescent↗
PubMed2001

Simultaneous immunomagnetic CD34+ cell selection and B-cell depletion in peripheral blood progenitor cell samples of patients suffering from B-cell non-Hodgkin's lymphoma.

The reduction of residual tumor cells is one of the main targets of leukapheresis product (LP) processing. Immunomagnetic enrichment/selection of CD34+ progenitor cells (Baxter Isolex 300i) can achieve a reduction of contaminating B-cells of approximately 2-3 logs in B-cell non-Hodgkin's lymphoma patients. Specific release of the enriched CD34+ cells (stem cell releasing agent PR34+; Baxter) and the use of antibody-coated immunobeads targeted against B-cell markers (CD10, CD19, CD20, CD22, CD23, and CD37) during this procedure allows the GMP-like simultaneous capture of residual B cells within a closed system. This combination of two purging techniques enhances the B-cell depletion capacity up to 4.5 logs. By performing 10 clinical-scale purging procedures, we could show that the simultaneous immunomagnetic purging method is easy to perform and highly efficient. We evaluated B-cell log depletion by flow cytometry for cases with marker-positive cells detectable before and after the purging procedure. The mean reduction of B-cells in these cases was 3.5 logs; the mean CD34+ cell yield and purity were 47 and 92%. Using three LPs, we tested the procedure on a modified Baxter Isolex 300i device with software adaptations for this procedure (software version 2.0) in direct comparison with CD34+ cell selection only, using the former version (version 1.12). The CD34+ cell yield was 49% (40-54%) for the CD34+ cell selection and 51% (19-72%) for simultaneous double selection. The mean purity was 96% for CD34+ cell selection and 98% for simultaneous double selection. B-cell depletion was 1.9 logs for CD34+ cell selection, and after simultaneous double selection, the B-cell content was decreased by 3.7 log steps (P = 0.0495). Clinical application of double-purged cells has not prolonged the hematopoietic recovery times after high-dose therapy as compared with nonpurged peripheral blood progenitor cell autotransplants. In conclusion, we could show that the simultaneous double selection protocol developed leads to a highly increased B-cell purging efficacy when compared with CD34+ cell selection without any negative effects regarding CD34+ cell yield and engraftment times after high-dose therapy.

Antigens, CD34↗
PubMed1997

Decrease in arterial oxygen partial pressure within the first 24 h of rhGM-CSF administration in AML patients.

GM-CSF may induce pulmonary complications, such as dyspnea with temporary decreases in oxygen saturation described as first dose effect for higher dosages of intravenous rhGM-CSF. This study investigated possible pulmonary disturbances in adult de novo AML patients receiving yeast rhGM-CSF 24 h prior to chemotherapy under phase II/III conditions. Eighteen patients were monitored for 22 treatment episodes. GM-CSF was given s.c. 1 q.d., 2 q.d. or continuously i.v. at 250 micrograms/m2/d 24 h prior to induction chemotherapy (TAD9, n = 18) and consolidation (TAD9, n = 4). Spirometry, bodyplethysmography, single breath-diffusion capacity (DLCO) and arterial blood gas analyses were obtained prior to GM-CSF, and repeated after 24 h. Pulse oxymetric oxygen saturation (saO2) was registered continuously for the first 16 h within day 1 of rhGM-CSF treatment. Patients were aged 21-75 years. The saO2 monitoring did not reveal any first dose effect. PaO2 values decreased from 78.9 mmHg before GM-CSF to 72.8 mmHg after 24 h (p < 0.01, maximum shift 15 mmHg). PaO2 shifts occurred mainly with pre-existing lowered paO2, but otherwise were independent of age, the route of GM-CSF administration, leukocyte levels, or increase of leukocytes with GM-CSF. Increases in AaDO2 reflected the paO2 shifts (p < 0.05). No dyspnea corresponded to these changes. DLCO values did not decrease significantly after 24 h. Summarily, contemporary dosage of yeast rhGM-CSF avoids short-term oxygen desaturations, but leads to clinically benign impairment in oxygen tension, based on ventilation/perfusion mismatches. This should be taken into account for patients starting at subnormal paO2.

Adult↗
PubMed1997

Hematopoietic growth factors in acute myeloid leukemia: supportive and priming effects.

Hematopoietic growth factors (GFs) are administered to patients who have acute myeloid leukemia (AML) in order to overcome two limitations of chemotherapy: (I) myelotoxicity, and (2) the chemoresistance of minimal residual disease. GFs have been used after chemotherapy in 11 clinical studies, 8 on older age or otherwise high-risk AML. The GFs used were granulocyte-macrophage colony-stimulating factor (GM-CSF) in 7, G-CSF in three and macrophage-CSF in one of the studies. Beneficial effects could be shown on the duration of neutropenia in 8 studies, frequency of infections or fever in 4 studies, mortality or survival in 2 studies and remission rate in 1 study. The benefits in remissions and survival were all found among high-risk patients. One study in younger patients found disadvantages in the remission rate and event-free survival, whereas there was no adverse effect of GF on therapy resistance, leukemic regrowth, or disease-free survival in the other studies. GF priming strategies are based on their stimulation of AML blasts in vitro, their modulation of cellular cytarabine (ARA-C) metabolism and enhancement of clonogenic cell kill by ARA-C. Protective effects of GF against clonogenic cell kill or apoptosis were also described. There are data from 10 clinical studies using GFs before or simultaneously with chemotherapy. One study showed significance, two others a tendency to longer disease-free survival, and two studies showed a trend toward more remissions. A disadvantage in the remission rate and survival was found in one study and prolonged thrombocytopenia in two studies. Nine of ten studies did not find evidence for an adverse effect of GF priming on the course of the disease. In most studies, GF priming was only administered in one or two chemotherapy courses. One study giving four to five courses found a reduction in relapses during the first 6 months. In conclusion, a supportive use of GF may have a place in high-risk, but not standard-risk AML. GF priming approaches may not have been adequately investigated and an extension of this strategy to more treatment courses now appears more promising. Based on the clinical data available, all administration of GF in AML should be regarded as investigational.

Acute Disease↗
PubMed1996

Rapid quantitative analysis of protein tyrosine residue phosphorylation in defined cell populations in whole blood and bone marrow aspirates.

We developed a rapid method for quantification of tyrosine phosphorylation in immunophenotypically defined cell populations in specimens of whole blood and unprocessed bone marrow. Samples were formaldehyde-fixed and cells were permeabilized. Phosphotyrosine residues and surface antigens were simultaneously stained by monoclonal antibodies and visualized by flow cytometry. The accuracy of the method was confirmed by demonstration of an increase of phosphotyrosine levels in pp60v-src transformed fibroblasts. In blood of healthy donors, monocytes and granulocytes showed higher levels of phosphotyrosine than lymphocytes. CD34+ peripheral blood stem cells showed slightly increased tyrosine phosphorylation compared to autologous lymphocytes. Significantly elevated levels of phosphotyrosine were demonstrated in leukaemic blasts compared to lymphocytes (P = 0.01).

Acute Disease↗
PubMed1995

Differential cell count and lymphocyte subsets in bronchoalveolar lavage during pneumonia with and without peripheral neutropenia.

One hundred immunocompromised HIV negative patients with microbiologically positive pneumonia underwent bronchoalveolar lavage (BAL) studies. Thirty cases showed peripheral neutropenia (< 1000 neutrophils/microL), 70 did not. The total cell number in BAL, the differential cell counts, and the lymphocyte subsets (CD4, CD8, CD19, CD57) were measured. Patients with pneumonia and normal or elevated peripheral neutrophils had a significantly increased total number of cells in BAL compared to patients with peripheral neutropenia (3.2 +/- 2 vs 1.3 +/- 0.6 x 10(5) cells/ml2 lavage fluid, p < 0.01). Ninety percent of the BAL differential cell counts obtained in patients exceeding 1000 neutrophils/microL showed a lymphocytic and/or neutrophilic alveolitis, whereas only 54% of patients with peripheral neutropenia displayed abnormal counts (p < 0.01). Yet the typical pattern of neutrophilic alveolitis was found more often for peripheral neutrophil counts over 1000/microL with high significance (p < 0.0001). Abnormal BAL cell patterns for neutropenic patients uniformly showed a lymphocytic alveolitis, only 10% additionally conformed with the pattern of neutrophilic alveolitis. Patients with pneumonia with and without peripheral neutropenia had similar findings in BAL lymphocyte subsets and exhibited a reduced CD4/CD8 ratio compared to controls (p < 0.05). The high susceptibility of severe neutropenic patients to pulmonary, especially fungal infections may be explained by the local lack of neutrophils.

Adolescent↗
PubMed1995

Pulmonary fungal infections in patients with hematological malignancies--diagnostic approaches.

In a retrospective study of 56 patients with hematological malignancies and fungal pneumonia we have analyzed the value of different diagnostic procedures. In all patients (Candida n = 29, Aspergillus n = 23, mixed fungal infection n = 4) bronchoscopy and/or high-resolution computed tomography of the lungs was performed. Cultural detection of fungi in bronchoalveolar lavage was successful in 23/32 Candida and 11/23 Aspergillus pneumonias. Other relevant pathogens were identified by bronchoscopy in 21 cases. Thorax CT scans showed diagnostic evidence of fungal pneumonia in 10/13 Candida and in 16/18 Aspergillus infections. Blood cultures were positive in 9/33 Candida pneumonias and in none of aspergillosis cases. Serological testing and surveillance cultures had only limited value for the early diagnosis of pulmonary mycosis. Our data suggest that bronchoscopy and high resolution CT scans are mutually complementary diagnostic tools with high sensitivity in patients with hematological malignancies and new pulmonary infiltrates. These procedures facilitate the early and reliable recognition of invasive fungal disease which may have a bearing on the initiation, length, and differential therapy of antimycotic drugs.

Adolescent↗
PubMed1995

Pulmonary infiltrates in patients with haematologic malignancies: clinical usefulness of non-invasive bronchoscopic procedures.

In a prospective study 90 patients with haematologic malignancies (57 acute leukaemias, 6 Hodgkin's Diseases, 15 Non-Hodgkin Lymphomas, 12 other diseases), with fever exceeding 38.4 degrees C and newly developed pulmonary infiltrates underwent bronchoscopy obtaining bronchoalveolar lavage, bronchial washings and protected brush specimen (n = 71). Pneumonias due to gram-negative bacteria (n = 38) and fungi (n = 34) were most frequent. Bronchoscopic specimens yielded 226 isolates (2 different organisms/bronchoscopy on average). 112 organisms were finally regarded as causing pneumonia. Sensitivity of bronchoscopy in diagnosing infectious episodes was 66%, but only 4 out of 13 non-infectious pulmonary infiltrates could be identified. Bronchoscopy was most effective in the diagnosis of pneumocystis carinii and herpes virus pneumonia, whereas sensitivity and specificity of detecting fungal and bacterial pneumonia were low. Empirical antimicrobial therapy was verified by evaluation of bronchoscopic samples in 25 out of 90 cases. Empirical therapy was successfully changed according to the results of invasive samplings in 34 out of 90 cases. Early identification of causative pathogens had a significant impact on survival.

Adolescent↗
PubMed1995

Pulmonary aspergillosis: early diagnosis improves survival.

Bronchoscopy obtaining bronchoalveolar lavage (BAL) fluid and bronchial secretions (BS) and/or high-resolution computed tomography (CT) of the lungs were performed in 33 patients with pulmonary aspergillosis from 1987 to 1992. The sensitivity of BAL fluid or BS for detecting histologically proven fungal disease was 33 and 50%, respectively, whereas positive serologies were only documented in 8% of the cases. CT scans contributed to the early diagnosis of opportunistic fungal pneumonia: characteristic CT signs were found in 16 of 19 episodes. The more frequent use of bronchoscopy and CT scans between 1990 and 1992 compared to 1987-1989 for the differential diagnosis of new pulmonary infiltrates resulted in earlier appropriate treatment. The average introduction of intravenous (i.v.) antifungal therapy after the onset of pneumonia was shifted from 12 to 7 days (p < 0.05). The timely implementation of i.v. antimycotic therapy had a significant impact on survival. Initiation of antifungal treatment later than 10 days after the onset of pneumonia resulted in a mortality of 90%, as opposed to 41% with an earlier start of antimycotics (p < 0.01). The earlier use of appropriate antifungal therapy in the second treatment period improved survival from 33 to 50% (NS). Bronchoscopy and high-resolution CT scans are mutually complementary diagnostic tools and should be performed as early as possible in the course of pneumonia for patients at high risk for aspergillosis.

Adolescent↗
PubMed1995

The role of decreased retinoblastoma protein expression in acute myelomonocytic and monoblastic leukemias.

The results of different investigators show that lack of p105 expression is relatively common in human myeloid leukemias, especially in monocytic leukemias. This suggests that loss of p105 expression could contribute to the altered growth control of these cells. So far no clear data exist which show that low p105 levels in AML blasts predict a poor therapy outcome. Therefore it is not very likely that p105 expression will become a strong prognostic factor for the different treatment strategies in AML.

Blotting, Southern↗
PubMed1994

New perspectives in the treatment of acute myeloid leukemia by hematopoietic growth factors.

The application of hematopoietic growth factors in the treatment on acute myeloid leukemia (AML) may principally aim at shortening the period of treatment associated neutropenia and reducing the rate of infectious complications by their post-therapeutic administration but may also be used to increase the sensitivity of leukemic blasts to antileukemic therapy by pretherapeutic growth stimulation. Both aspects were addressed in subsequent clinical phase II studies and preclinical investigations. In a first clinical trial, 36 patients with high-risk AML received granulocyte-macrophage colony-stimulating factor (GM-CSF) after successful cytoreductive chemotherapy and experienced a shortening of the period of post-therapeutic neutropenia by 6 to 9 days, leading to a significant reduction of treatment-associated deaths from 39% to 14%. In preclinical studies an enhancement of the cytotoxicity of cytosine arabinoside (AraC) on leukemic blasts could be shown by pretreatment with GM-CSF or IL-3. Investigations on the impact of hematopoietic growth factors on the intracellular metabolism of AraC indicated that this effect was primarily mediated by an increase in the activity of DNA-polymerase-alpha. The evaluation of different doses of AraC showed the most marked increase after the combination of GM-CSF with conventional rather than high doses of AraC. Based on these preclinical experiments, a prospective randomized trial was subsequently initiated investigating the effect of GM-CSF before and during induction, consolidation, and the first two cycles of maintenance chemotherapy in newly diagnosed AML. This ongoing trial has enrolled 67 patients at the current time. An early interim analysis showed no differences in remission rates but a tendency toward a longer remission duration in patients receiving GM-CSF. These data indicate that hematopoietic growth factors like GM-CSF in particular may provide a new perspective in the treatment of acute myeloid leukemia with the possibility of reducing treatment associated mortality and perhaps of increasing the efficacy of antileukemic treatment.

Acute Disease↗
PubMed1994

Experimental basis for the use of recombinant human granulocyte-macrophage colony-stimulating factor in patients with acute myeloid leukemia.

Granulocyte-macrophage colony-stimulating factor (GM-CSF) not only stimulates hematopoiesis, but also induces the proliferation and differentiation of leukemic myeloid cells. The observation that clonogenic growth of malignant cells can be induced in vitro has led to the development of therapeutic concepts that aim to increase the sensitivity of cells to cytostatic and cytotoxic agents by priming them with GM-CSF. In in vitro experiments, preincubating leukemic cells with recombinant cytokines including GM-CSF led to a consistent, dose-dependent increase in the cytotoxicity of cytosine arabinoside (Ara-C). This effect has since been observed in patients with acute myeloid leukemia (AML) although its mechanism is not yet entirely clear. It seems that GM-CSF increases the relative number of cells in the S phase of the cell cycle and enhances the activity of DNA polymerases, enzymes that are essential to nucleotide incorporation into DNA. Based on these experimental results, numerous clinical trials have investigated the role of GM-CSF in priming leukemic blasts before chemotherapy. These studies will allow us to determine whether our in vitro observations of increased cytotoxicity translate into higher remission rates and durations, and will help us to identify the patient subgroups most likely to benefit from this therapeutic approach.

Acute Disease↗
PubMed1994

Modulation of intracellular metabolism of cytosine arabinoside in acute myeloid leukemia by granulocyte-macrophage colony-stimulating factor.

The current study investigated the effect of granulocyte-macrophage colony-stimulating factor (GM-CSF) on the intracellular metabolism and cytotoxicity of 1-beta-D-arabinofuranosylcytosine (araC) in leukemic cells of 45 patients with acute myeloid leukemia (AML). AML blasts from bone marrow (BM) (n = 39) and peripheral blood (PB) (n = 17) were incubated for 48 h with or without GM-CSF (100 U/ml) followed by a concurrent treatment with increasing concentrations of araC (0.06-100 microM) for an additional 24 h. After GM-CSF a 1.5-8.4-fold (median 2.3) increase in 3H-araC incorporation into the DNA was observed in ten of 14 peripheral blast specimens and in 23 of 28 bone marrow samples, 18 of whom also showed an enhanced 3H-TdR incorporation (1.5-8.5-fold, median 2.0-fold). Four different types of response were identified when analyzing 3H-araC incorporation into the DNA of bone marrow samples in relation to the applied araC dose: (i) 8/28 cases had increases of the araC incorporation at all araC dose levels applied (0.06-100 microM), (ii) 12/28 at low araC concentrations only (0.06-1.0 microM), (iii) 3/28 at high araC concentrations only (10-100 microM), and (iv) 5/28 showed no increase at any dose level given. Hence, 20 of the 23 responding patients revealed a GM-CSF induced enhancement of araC incorporation at low or conventional doses of araC (0.06-1.0 microM). Fourteen of the 18 cases with concomitant rises of 3H-TdR and 3H-araC incorporation into the DNA after GM-CSF had elevated DNA polymerase alpha activity (16-531%, median 72%) and in ten cases overall DNA polymerase activity was enhanced (10-70%, median 22.5%). In contrast, thymidine kinase (TK) and deoxycytidine kinase (dCK) activity were elevated after GM-CSF in only ten and five patients, respectively. An increase in the fraction of cells in S phase was found in 11/21 bone marrow specimens and in 5/9 peripheral blast samples. However, no correlation was observed between increases in the proportion of cells in S phase and enhancements in enzyme activities. In 13 cases the cytotoxicity of araC with and without GM-CSF was assessed by means of a blast cell colony assay. Preincubation with GM-CSF increased the araC mediated cytotoxicity in ten of 13 patients by a median of 3.2-fold (range 2.2-229-fold). The respective LD50 values for araC were reduced from 0.45 to 0.19 microM on average.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1993

The role of GM-CSF in the treatment of acute myeloid leukemia.

After a first study showed that GM-CSF following chemotherapy effectively accelerated neutrophil recovery and reduced early mortality in high risk patients with AML, a second study was begun in which GM-CSF was applied preceding chemotherapy and continuing until neutrophil recovery in the initial 5 chemotherapy courses for patients with newly diagnosed AML. The CR rate in patients of 16-75 (median 50) years was 75% in GM-CSF patients and 84% in controls. GM-CSF patients showed a trend to more frequent rapid blast clearance and fewer persistent leukemias and a significantly superior remission duration as of this update two-and-a-half years after the study started. It should be shown later by this study whether GM-CSF multiple course priming and longterm administration adds to the cure rate of patients with AML.

Adolescent↗
PubMed1992

Differences in the intracellular pharmacokinetics of cytosine arabinoside (AraC) between circulating leukemic blasts and normal mononuclear blood cells.

The increasing insights into the pharmacokinetics and the metabolism of cytosine arabinoside (AraC) have improved the rationale for its application in leukemia therapy and have led to a pharmacologically directed design of antileukemic treatment. The current study aims at adding to this approach by detecting differences in the intracellular metabolism of AraC 5'-triphosphate (AraCTP) between leukemic and normal mononuclear blood cells. Measurements of intracellular AraCTP levels were complemented by determinations of plasma AraC and AraU concentrations and were performed in 32 patients with acute myeloid leukemia undergoing combination therapy including either conventional (100 mg/m2 daily) or high-dose (1.0 or 3.0 g/m2 twice daily) AraC. Plasma AraC concentration showed a linear relationship to the applied AraC dose but did not correlate with intracellular AraCTP levels. During conventional-dose AraC therapy little interpatient variation was observed in AraCTP retention times in leukemic blasts from 5 patients with t1/2 values ranging from 1.70 to 2.50 h (median 2.14 h). In all cases AraCTP levels declined rapidly after the end of the AraC infusion. Substantial differences in AraCTP retention times were revealed, however, during 3 h infusions of either 1.0 or 3.0 g/m2 AraC in leukemic blasts from 10 patients with t1/2 values between 1.60 to 7.63 h (median 2.42 h). In addition, AraCTP levels declined in only one patient by > 10% within the first hour after the end of therapy and remained constant or even increased up to 1.5-fold in a post-treatment period of 1 to 2.5 h in the other nine cases. In contrast, AraCTP retention times were relatively uniform in normal mononuclear blood cells from 11 patients with t1/2 values of 3.34 to 5.29 h (median 3.85 h). More importantly, AraCTP levels dropped by > 10% within the first hour after the end of the high-dose AraC infusion in eight of 11 cases. A post-therapeutic increase > 10% was not observed in any patient. Similar findings emerged after in vitro exposure of normal bone marrow cells from six healthy volunteers to 20 mumol/l AraC for 3 h revealing a > 10% decrease of intracellular AraCTP within the first post-treatment hour in all cases with AraCTP retention times of 2.29 to 8.63 h (median 3.20 h). These differences in AraCTP pharmacokinetics between leukemic and normal blood cells may provide the basis for a modified timing of AraC administration with the aim of selectively maintaining cytotoxic AraCTP levels in leukemic blasts while allowing an intermittent drop of AraCTP levels in normal cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Acute Disease↗