Search PubMed⌕ Search

Biomedical subjects

M Lehnert

Publications and source records attributed to M Lehnert.

At least 19 recordsLinked to original sources
PubMed2000

The prevalence of BRCA1 mutations in Chinese patients with early onset breast cancer and affected relatives.

The purpose of this study was to determine the prevalence of BRCA1 mutations in Chinese breast cancer patients in Singapore. BRCA1 analysis was conducted in consecutive patients with breast cancer before the age of 40 years (76 women), or whose relatives had breast or ovarian cancer (16 women). Ten patients had both early onset breast cancer and affected relatives. Genomic DNA from peripheral mononuclear blood cells was studied by using the protein transcription-translation assay (exon 11) and single-strand conformational polymorphism, with subsequent DNA sequencing. All six disease-causing mutations occurred in women under 40 years (8.6%) with three occurring in patients under 35 years (three out of 22 patients, 13.6%). Mis-sense mutations of unknown significance were found in three patients. Two of the ten women with affected relatives under 40 years had BRCA1 mutations. The prevalence of BRCA1 mutations in Chinese patients with early onset breast cancer is similar to that observed in Caucasian women. Most Chinese patients with affected relatives were not carriers of BRCA1 mutations.

Adult↗
PubMed2000

Phase II trial of docetaxel in Asian patients with inoperable stage III non-small cell lung cancer.

Docetaxel has a response rate of greater than 30% in first-line treatment of Western patients with advanced non-small cell lung cancer (NSCLC). The goal of this open-label. phase II study was to evaluate the activity and safety profile of docetaxel in Asian patients with inoperable untreated stage III NSCLC. Docetaxel was given at 100 mg/m2 as a 1-h infusion every 3 weeks. Prophylactic dexamethasone was given to reduce hypersensitivity reactions and edema. Thirty-five patients were enrolled in the study. The response rate was 34% (95% CI, 19%-50%) according to intent-to-treat analysis. No complete response was observed. Twenty-four patients (69%) had grade 3 or 4 neutropenia in cycle 1, and febrile neutropenia was seen in 12 patients. Six patients (17%) experienced mild fluid retention. Docetaxel is an active agent in first-line treatment of Asian patients with locally advanced NSCLC, with the main toxicity being neutropenia. Fluid retention was a minor problem in this study.

Adult↗
PubMed1999

Factors associated with tumor volume and primary metastases in Ewing tumors: results from the (EI)CESS studies.

BACKGROUND: Tumor volumes of more than 100 ml and the presence of primary metastases have been identified as determinants of poor prognosis in patients with Ewing tumors. We sought to assess the prevalence of critical tumor size and primary metastases in a large national sample of patients at the time of first diagnosis and to identify factors that are associated with their occurrence. PATIENTS: The present report is based on data of 945 German patients who were enrolled into the (EI)CESS therapy studies between 1980 and 1997. It is assumed that registration of German patients with Ewing tumors under the age of 15 years was almost complete since around 1985. Diagnoses of primary tumors were ascertained exclusively by biopsies. Analyses were restricted to patients with Ewing tumors of bone due to the few occurrences in soft tissues. METHODS: Tumor volume data as assessed by radiography, computed tomography or nuclear magnetic imaging were available for 821 patients. The diagnosis of primary metastases was based on thoracic computed tomography or on whole body bone scans in 936 patients. Suspicious lesions had to be confirmed by bone marrow biopsies. We explored how year of first diagnosis, age at first diagnosis, sex, histological subtype and site of the primary tumor related to tumor size and presence of metastases by univariate and multivariate statistical techniques. RESULTS: Sixty-eight percent of the patients (n = 559) had a volume above 100 ml with smaller tumors being more common in childhood than in late adolescence and early adulthood. Extensive volumes were observed in almost 90% of the tumors located in femur and pelvis while they were less common in other sites (P < 0.001). On average, 26% of all patients presented with clinically apparent primary metastases. The detection rate of metastases was markedly higher in patients diagnosed after 1991 (P < 0.001). Primary metastases were also significantly more common for tumors originating in the pelvis and for peripheral neuroectodermal tumors (PNET; P < 0.01). Tumors greater than 100 ml were positively associated with metastatic disease (P < 0.001). Multivariate analyses, which included simultaneously all univariate predictors in a logistic regression model, indicated that most of the observed associations were essentially unconfounded. The adjusted odds ratios (OR) for the presence of tumor volumes > or = 100 ml were OR = 1.5 per age rise of 10 years, and OR = 5.8 for pelvis and OR = 7.1 for femur as primary tumor site (all P < 0.001). The presence of metastases was significantly associated with the year of diagnosis (OR = 1.9, after 1991 vs. before 1986), pelvis as site of the primary tumor (OR = 1.8), a PNET (OR = 1.5), and tumor size > or = 100 ml (OR = 1.6). CONCLUSIONS: In conclusion, we find that the prevalence of established factors for an unfavorable prognosis is disturbingly high among patients diagnosed with Ewing tumors. Recent progress in imaging techniques seems to account for much of the rise in the detection rate of metastases after 1991. We identify age and, in particular pelvic and femoral site as the major determinants of local tumor extension. Occurrence of primary metastases is independently related to tumor size, pelvic site, and PNET.

Adolescent↗
PubMed1999

[Lymphomas and leukemias in population-related cancer registries in Germany].

BACKGROUND: A German Federal law enacted in 1995 aims at nation-wide cancer registration, the details of realization based on local regulations being left to the individual Federal states. The impact of different approaches and regulations on the results of registration was investigated at three well-established records in the Saarland, Hamburg and North-Rhine Westphalia, taking the group of lymphoma and leukaemia (ICD 200-208) taken as an example. MATERIAL AND METHODS: Incidence and mortality rates calculated by the record files for the period from 1987 to 1994 were compared. The resulting mortality/incidence ratios were compared as well as the percentage of cases in each register with death certificates (DCO) as the only information source. RESULTS: There was a distinct increase of incidence rates visible in Hamburg and Münster. As far as the male patients was concerned, both records attained the level of Saarland at the end of the period. However, the leukaemia and lymphoma mortality figures for males and females was about 10% lower for Saarland than in the comparative regions. The male mortality incidence ratio was 0.55 for Saarland versus 0.60 average in Hamburg and Münster at the end of the period. In Saarland and Hamburg there was a decrease of DCO-cases from 14% to less than 6% in 1994. More constant values around 11% could be observed in the Münster registry. The distribution of diagnosis within the group as well as age-specific incidence rates for the selected diagnosis "lymphatic leukaemia" (ICD 204) and "Hodgkin's disease" (ICD 201) yielded only slight differences. CONCLUSION: The increase of incidence rates in Münster and Hamburg indicates more complete reporting. Assuming that the survival rates are the same in the three regions, the lower mortality in Saarland points to lower morbidity. Hence in spite of a definite approximation the cancer registries in Hamburg and Münster do not reach the level of completeness of the Saarland cancer registry. This may be due to the informed patient consent required by regional law for reports to the registry. To achieve completeness a special reporting procedure for pathological and haematological Institutes is mandatory. Simple indicators should be available in each registry for continuous estimation of completeness. Standardised case definitions and rules for the coding of diagnosis in cancer registries will improve national and international comparability and feasibility of data exchange.

Adolescent↗
PubMed1998

Phase II trial of dexverapamil and epirubicin in patients with non-responsive metastatic breast cancer.

Agents capable of reversing P-glycoprotein-associated multidrug resistance have usually failed to enhance chemotherapy activity in patients with solid tumours. Based on its toxicity profile and experimental potency, dexverapamil, the R-enantiomer of verapamil, is considered to be promising for clinical use as a chemosensitizer. The purpose of this early phase II trial was to evaluate the effects of dexverapamil on epirubicin toxicity, activity and pharmacokinetics in patients with metastatic breast cancer. A two-stage design was applied. Patients first received epirubicin alone at 120 mg m(-2) i.v. over 15 min, repeated every 21 days. Patients with refractory disease continued to receive epirubicin at the same dose and schedule but supplemented with oral dexverapamil 300 mg every 6 h x 13 doses. The Gehan design was applied to the dexverapamil/epirubicin cohort of patients. Thirty-nine patients were entered on study, 25 proceeded to receive epirubicin plus dexverapamil. Dexverapamil did not increase epirubicin toxicity. The dose intensity of epirubicin was similar when used alone or with dexverapamil. In nine intrapatient comparisons, the area under the plasma concentration-time curve (AUC) of epirubicin was significantly reduced by dexverapamil (mean 2968 vs 1901 microg ml[-1] h[-1], P= 0.02). The mean trough plasma levels of dexverapamil and its major metabolite nor-dexverapamil were 1.2 and 1.5 microM respectively. The addition of dexverapamil to epirubicin induced partial responses in 4 of 23 patients evaluable for tumour response (17%, CI 5-39%, s.e.P 0.079). The remissions lasted 3, 8, 11 and 11+ months. These data suggest that the concept of enhancing chemotherapy activity by adding chemosensitizers may function not only in haematological malignancies but also in selected solid tumours. An increase in the AUC and toxicity of cytotoxic agents does not seem to be a prerequisite for chemosensitizers to enhance anti-tumour activity.

Adult↗
PubMed1998

Characteristics and prognosis of KI-1 positive anaplastic large cell lymphoma in Asians.

BACKGROUND: Ki-1 positive anaplastic large cell lymphoma is a rare type of non-Hodgkin's lymphoma (NHL), and has not been extensively described in Asian patients. AIM: To evaluate the clinical characteristics, prognostic factors and treatment outcome of Ki-1 positive lymphoma in an Asian community. METHODS: A retrospective analysis of all patients with CD30 antigen positive anaplastic large cell lymphoma from 1987 to 1996 in a single institution. RESULTS: Of 218 patients with NHL, ten (5%) were identified with Ki-1 positive anaplastic large cell lymphoma. Eight were Chinese, two Indians. The male:female ratio was 1.5:1, and the median age was 32 years. Seven patients presented with B-symptoms, and five had stage III/IV disease. The majority (seven of ten) was low- or low-intermediate risk according to the International Prognostic Index (IPI). Four out of five cases immunophenotyped showed a T-cell origin. Five out of eight patients who received first-line combination chemotherapy achieved a complete remission. Two relapsed, with one being re-induced into a durable second remission. One patient with recurrent cutaneous lymphoma received solely radiotherapy and was disease-free at 20+ years from diagnosis. At analysis, two patients had died, five were disease-free at four, 27, 78, 89 months and 20 years respectively, and three were alive with disease. The IPI appears to have prognostic significance. CONCLUSION: Incidence and clinical characteristics in our Asian patients were similar to those described in Western populations. The IPI appears to have prognostic relevance. In approximately one-third of patients, long term survival can be achieved with standard treatment.

Adolescent↗
PubMed1997

Intermittent exposure to doxorubicin in vitro selects for multifactorial non-P-glycoprotein-associated multidrug resistance in RPMI 8226 human myeloma cells.

The purpose of the present study was to evaluate whether intermittent exposure to a constant dose of doxorubicin selects for multidrug resistance (MDR) in RPMI 8226 human myeloma cells and, if so, to determine the molecular mechanism. In an attempt to approximate clinical doxorubicin treatment in vitro, cells were exposed to a fixed dose of doxorubicin for 4 d alternating with growth in drug-free medium for 17 d. An MDR subline emerged, termed 8226/DOXint5, which was 3-4-fold resistant to doxorubicin, etoposide and m-AMSA, and 1.6-fold resistant to vincristine. Sensitivity to docetaxel, melphalan and cisplatin was normal. Verapamil normalized vincristine sensitivity but had little effect on resistance to the other agents. Cellular uptake and retention of daunorubicin and vincristine were reduced by approximately 10%. The 8226/DOXint5 cells showed diminished DNA topoisomerase IIalpha expression and increased expression of the multidrug resistance protein MRP. Expression of MDR1/P-glycoprotein was not detected. Immunostaining showed 70% of the cells to over-express the lung-resistance protein LRP. This new MDR myeloma cell line may prove to be a useful model for the development of strategies to overcome low-level, multifactorial MDR, which might be a common phenomenon in clinical myeloma treated with doxorubicin.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1997

Randomized comparison of total androgen blockade alone versus combined with weekly epirubicin in advanced prostate cancer.

Hormone deprivation is the gold standard for the treatment of metastatic prostate cancer. However, prostate cancer being primarily a heterogeneous tumor comprising hormone-dependent, hormone-sensitive, and hormone-insensitive cells, at least the latter remain unaffected by hormonal manipulations, thus making disease progression almost inevitable. In quest of a more comprehensive therapy we therefore studied the concept of early combined chemoendocrine therapy in a prospective randomized multicenter trial. The purpose of this study was to evaluate whether patients with previously untreated advanced prostate cancer benefit from combining total androgen blockade (TAB) with weekly epirubicin chemotherapy (E-TAB). From April 1988 to January 1991, 145 previously untreated patients with either metastatic (n = 117) or locally advanced (n = 28) histologically confirmed prostate cancer were randomly allocated to treatment with TAB by bilateral orchiectomy and flutamide 250 mg t.i.d. or TAB plus weekly epirubicin 25 mg/m2 i.v. for 18 weeks (E-TAB). The study endpoints were progression-free survival and overall survival. In addition the effects of treatment on quality of life were assessed by two methods. At regular intervals patients self-assessed ten qualities of physical, functional and emotional health using 5-point scales. In order to evaluate the time without disease progression and treatment-induced adverse effects, a modified Q-TWiST (quality-adjusted time without symptoms and toxicity) model was applied. At a median follow-up of 81 months, progression-free survival and overall survival in the TAB and E-TAB groups were 12 and 18 months (p < 0.02) and 22 and 30 months (p = 0.12), respectively. In patients with > 5 sites of bone metastasis (D2max), the corresponding periods were 9 and 14 months (p = 0.005) and 17 and 27 months (p = 0.06), respectively. Subjective quality of life assessment showed no impairment of quality of life by epirubicin treatment. Stage D and D2max patients treated with E-TAB had an average gain in Q-TWiST of 5 months (p = 0.098) and 8 months (p = 0.03), respectively, compared to the TAB treatment. Objective toxicities were generally mild with either treatment. In conclusion, the combination of TAB and epirubicin was well tolerated by patients with advanced prostate cancer and resulted in a significant extension of progression-free survival. This effect of E-TAB on objective treatment outcome was accompanied by prolonged time without treatment-induced adverse effects and tumor progression, i.e., time with good quality of life. Therefore, further studies with E-TAB appear warranted in patients with advanced prostate cancer.

Aged↗
PubMed1996

Tumor necrosis factor alpha is a powerful apoptotic inducer in lymphoid leukemic cells expressing the P-170 glycoprotein.

Multidrug resistance (MDR) is a phenomenon by which tumor cells exposed to a single anti-proliferative agent acquire resistance to other structurally and functionally unrelated drugs. The classical form of MDR is caused by a plasma-membrane protein currently named P-glycoprotein or P-170 encoded by the human mdr-1 gene in its functional isoform. In vitro cell lines expressing P-170 usually also present phenotypic and functional alterations. In the present study we report that the cytotoxicity mediated by tumor necrosis factor alpha (TNF alpha) in MDR variants of the human T-lymphoblastoid CEM cell line is associated with apoptosis (programmed cell death). Susceptibility of MDR cells to apoptosis was increased upon cycloheximide + TNF alpha sequential treatment, whereby the impairment of protein synthesis due to the former agent was followed by the effect of cytokine exposure. Massive apoptosis of P-170-positive cells, but not of controls, was also obtained by depletion of nutrients (i.e., serum starvation). In contrast, TNF-alpha exerted a similar apoptotic effect in epithelial (MCF-7) or myeloma (S8226) drug-sensitive/ -resistant cell pairs. However, the MDR variant of myeloma S8226 was more sensitive to the cytostatic effect of TNF alpha than the parental drug-sensitive cell line. These results suggest that the presence of the MDR phenotype may be associated with increased histotype-dependent cell susceptibility to specific, protein-synthesis-independent, apoptotic pathways.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1996

Methods to detect P-glycoprotein-associated multidrug resistance in patients' tumors: consensus recommendations.

Multidrug resistance (MDR), especially that associated with overexpression of MDR1 and its product, P-glycoprotein (Pgp), is thought to play a role in the outcome of therapy for some human tumors; however, a consensus conclusion has been difficult to reach, owing to the variable results published by different laboratories. Many factors appear to influence the detection of Pgp in clinical specimens, including its low and heterogeneous expression; conflicting definitions of detection end points; differences in methods of sample preparation, fixation, and analysis; use of immunological reagents with variable Pgp specificity and avidity and with different recognition epitopes; use of secondary reagents and chromogens; and differences in clinical end points. Also, mechanisms other than Pgp overexpression may contribute to clinical MDR. The combined effect of these factors is clearly important, especially among tumors with low expression of Pgp. Thus, a workshop was organized in Memphis, Tennessee, to promote the standardization of approaches to MDR1 and Pgp detection in clinical specimens. The 15 North American and European institutions that agreed to participate conducted three preworkshop trials with well-characterized MDR myeloma and carcinoma cell lines that expressed increasing amounts of Pgp. The intent was to establish standard materials and methods for a fourth trial, assays of Pgp and MDR1 in clinical specimens. The general conclusions emerging from these efforts led to a number of recommendations for future studies: (a) although detection of Pgp and MDR1 is at present likely to be more reliable in leukemias and lymphomas than in solid tumors, accurate measurement of low levels of Pgp expression under most conditions remains an elusive goal; (b) tissue-specific controls, antibody controls, and standardized MDR cell lines are essential for calibrating any detection method and for subsequent analyses of clinical samples; (c) use of two or more vendor-standardized anti-Pgp antibody reagents that recognize different epitopes improves the reliability of immunological detection of Pgp; (d) sample fixation and antigen preservation must be carefully controlled; (e) multiparameter analysis is useful in clinical assays of MDR1/Pgp expression; (f) immunostaining data are best reported as staining intensity and the percentage of positive cells; and (g) arbitrary minimal cutoff points for analysis compromise the reliability of conclusions. The recommendations made by workshop participants should enhance the quality of research on the role of Pgp in clinical MDR development and provide a paradigm for investigations of other drug resistance-associated proteins.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1996

Serum can inhibit reversal of multidrug resistance by chemosensitisers.

The purpose of this study was to evaluate to what extent the ability of various chemosensitisers (CS) to reverse P-glycoprotein-associated multidrug resistance (MDR) is reduced when tested in physiological serum protein concentrations. Utilising drug sensitivity and accumulation assays, the CS were tested in medium containing 10% fetal bovine serum and in 100% horse or human serum. Two RPMI 8226 human myeloma sublines were used which express different levels of P-glycoprotein. The CS were tested at various concentrations, including clinically achievable blood levels. When using the CS at high doses, wide differences were observed in the extent CS activity was diminished by serum. Verapamil, cyclosporin A and quinine were not affected, quinidine and medroxyprogesterone acetate were moderately inhibited, and amiodarone and trifluoperazine were largely inactivated. When the CS were used at concentrations achievable in humans, the activity of all agents except quinine was markedly reduced by serum. With respect to the extent to which CS activity was diminished by serum, good statistical correlation (r > 0.90, P < 0.001) was found between the use of cytotoxicity and drug accumulation assays, horse and human serum or cell lines with high and low levels of P-glycoprotein, respectively. These studies demonstrated that physiological serum protein concentrations can profoundly diminish the MDR reversing activity of particular CS. Some drugs, such as amiodarone and trifluoperazine, are largely inactivated by serum when used at a wide range of concentrations. Other agents, such as verapamil and cyclosporin A, are essentially unaffected when used at high doses but markedly inhibited at concentrations achievable in humans. These data suggest that in vitro studies of CS in medium containing low serum protein concentrations can result in misleading conclusions regarding the potential clinical activity of such agents.

Animals↗
PubMed1996

A randomized phase II study with two schedules of the novel indoloquinone EO9 in non-small-cell lung cancer: a study of the EORTC Early Clinical Studies Group (ECSG).

In a multicentre randomized trial of the EORTC-ECSG, we have treated 38 chemotherapy naïve patients with advanced non-small-cell lung cancer (NSCLC) with EO9, a novel bio-reductive alkylating indoloquinone. The drug was given at two different dose schedules by a single bolus i.v. injection: arm A 12 mg/m2 weekly and arm B 22 mg/m2 every three weeks. All together 185 courses were administered (145 in arm A and 40 in arm B). The major toxicity was reversible proteinuria more frequently occurring in the three-weekly schedule (arm A 34.5% vs. arm B 62.5%). Creatinine elevation, fluid retention and pericardial or pleural effusion were also recorded in a limited number of patients. Other common toxicities more frequent in the three-weekly administration were asthenia (21% vs. 35% of cycles), nausea (15% vs. 27.5% of cycles) and vomiting (5% vs. 17.5% of cycles). Toxicities were mainly of grade I and II. No responses have been observed. Five patients (26%) on arm A and eight (53%) on arm B experienced stable disease. These doses and schedules of EO9 do not yield activity in NSCLC.

Adult↗
PubMed1996

Sensitive and rapid bioassay for analysis of P-glycoprotein-inhibiting activity of chemosensitizers in patient serum.

Clinical studies of agents capable of reversing P-glycoprotein (Pgp)-mediated multidrug resistance have attracted much attention in recent years. One question of interest in such studies is whether the concentrations achieved by chemosensitizers are sufficient to inhibit Pgp function. The goal of the present study was to develop a reliable ex vivo bioassay for analysis of the Pgp-inhibiting activity of chemosensitizer-containing patient serum. The fluorescent Pgp substrates daunorubicin (DNR) and rhodamine 123 (R123) were used as probes for Pgp function. The 8226/DOX6 human myeloma cell line, which expresses Pgp at levels that can be detected in clinical cancers, was used as a model system. The index chemosensitizers tested were dexverapamil (DVPM) and cyclosporin A, with particular focus on DVPM. Using flow cytometry, chemosensitizer effects on 1-h drug accumulation and on drug retention at 30 min were evaluated. In the studies using pooled human serum spiked in vitro with graded chemosensitizer concentrations, the order of assay sensitivity was R123 retention >>> R123 accumulation > DNR retention equal to DNR accumulation. Keeping serum spiked with DVPM for several hours at room temperature or 4 degreesC or for several months at -80 degreesC had no effect on Pgp-blocking activity. Sixteen blood samples from patients with metastatic breast cancer receiving DVPM to overcome epirubicin resistance were analyzed for Pgp-inhibiting activity and for levels of DVPM and nor-DVPM, the major metabolite of verapamil. Each patient sample was found capable of increasing R123 retention in the 8226/DOX6 cells, with activity factors of 3- to 8-fold and good agreement between DVPM blood levels and bioassay activity (r = 0.7168; two-sided P = 0.0018). The R123 retention assay developed and validated in this study seems to be a sensitive, reproducible, and easy-to-use method for analysis of Pgp-inhibiting activity of chemosensitizer-containing human serum. The assay seems capable of estimating DVPM blood levels and could prove to be a valuable tool for monitoring chemosensitizer treatment in cancer patients.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1995

Randomised phase II study of epirubicin-vindesine versus mitoxantrone-vindesine in metastatic breast cancer.

The purpose of this study was to compare the activity and toxicity of epirubicin-vindesine (EV) with mitoxantrone-vindesine (MV) in patients with metastatic breast cancer. A total of 295 patients was randomly allocated to treatment with vindesine 3 mg/m2 combined with either epirubicin 40 mg/m2 or mitoxantrone 10 mg/m2. All drugs were given by intravenous push, treatment cycles were repeated at 3-4 week intervals. 255 patients were available for response, and 283 for toxicity. EV and MV yielded similar objective response rates (34 and 26%, respectively), response durations, times to progression and survival. Median time to remission was 1.8 and 3.1 months (P = 0.006) with EV and MV, respectively. In patients with visceral metastases, response rate was higher with EV than MV (40 versus 23%; P = 0.03). Patients receiving MV had less nausea/vomiting (P = 0.007) and alopecia (P = < 0.001) of WHO grade > or = 2. Bone marrow, cardiac and other toxicities were mild with both treatments. The observed differences in activity and toxicity between the two regimens appear to have clinical relevance. EV proved to be more active in visceral disease and to be able to induce remissions more rapidly. Accordingly, patients with visceral metastases or severe tumour-related symptoms may benefit from epirubicin-based treatment. Subjective toxicities, i.e. nausea/vomiting and alopecia, were less frequent and severe with MV. Thus, MV may prove useful in patients with more indolent disease and appears to warrant phase III evaluation in such patients.

Adult↗