(1/750) Atypical multidrug resistance: breast cancer resistance protein messenger RNA expression in mitoxantrone-selected cell lines.

BACKGROUND: Human cancer cell lines grown in the presence of the cytotoxic agent mitoxantrone frequently develop resistance associated with a reduction in intracellular drug accumulation without increased expression of the known drug resistance transporters P-glycoprotein and multidrug resistance protein (also known as multidrug resistance-associated protein). Breast cancer resistance protein (BCRP) is a recently described adenosine triphosphate-binding cassette transporter associated with resistance to mitoxantrone and anthracyclines. This study was undertaken to test the prevalence of BCRP overexpression in cell lines selected for growth in the presence of mitoxantrone. METHODS: Total cellular RNA or poly A+ RNA and genomic DNA were isolated from parental and drug-selected cell lines. Expression of BCRP messenger RNA (mRNA) and amplification of the BCRP gene were analyzed by northern and Southern blot hybridization, respectively. RESULTS: A variety of drug-resistant human cancer cell lines derived by selection with mitoxantrone markedly overexpressed BCRP mRNA; these cell lines included sublines of human breast carcinoma (MCF-7), colon carcinoma (S1 and HT29), gastric carcinoma (EPG85-257), fibrosarcoma (EPF86-079), and myeloma (8226) origins. Analysis of genomic DNA from BCRP-overexpressing MCF-7/MX cells demonstrated that the BCRP gene was also amplified in these cells. CONCLUSIONS: Overexpression of BCRP mRNA is frequently observed in multidrug-resistant cell lines selected with mitoxantrone, suggesting that BCRP is likely to be a major cellular defense mechanism elicited in response to exposure to this drug. It is likely that BCRP is the putative "mitoxantrone transporter" hypothesized to be present in these cell lines.  (+info)

(2/750) Multiple mechanisms confer drug resistance to mitoxantrone in the human 8226 myeloma cell line.

Selection for in vitro drug resistance can result in a complex phenotype with more than one mechanism of resistance emerging concurrently or sequentially. We examined emerging mechanisms of drug resistance during selection with mitoxantrone in the human myeloma cell line 8226. A novel transport mechanism appeared early in the selection process that was associated with a 10-fold resistance to mitoxantrone in the 8226/MR4 cell line. The reduction in intracellular drug concentration was ATP-dependent and ouabain-insensitive. The 8226/MR4 cell line was 34-fold cross-resistant to the fluorescent aza-anthrapyrazole BBR 3390. The resistance to BBR 3390 coincided with a 50% reduction in intracellular drug concentration. Confocal microscopy using BBR 3390 revealed a 64% decrease in the nuclear:cytoplasmic ratio in the drug-resistant cell line. The reduction in intracellular drug concentration of both mitoxantrone and BBR 3390 was reversed by a novel chemosensitizing agent, fumitremorgin C. In contrast, fumitremorgin C had no effect on resistance to mitoxantrone or BBR 3390 in the P-glycoprotein-positive 8226/DOX6 cell line. Increasing the degree of resistance to mitoxantrone in the 8226 cell line from 10 to 37 times (8226/MR20) did not further reduce the intracellular drug concentration. However, the 8226/MR20 cell line exhibited 88 and 70% reductions in topoisomerase II beta and alpha expression, respectively, compared with the parental drug sensitive cell line. This decrease in topoisomerase expression and activity was not observed in the low-level drug-resistant, 8226/MR4 cell line. These data demonstrate that low-level mitoxantrone resistance is due to the presence of a novel, energy-dependent drug efflux pump similar to P-glycoprotein and multidrug resistance-associated protein. Reversal of resistance by blocking drug efflux with fumitremorgin C should allow for functional analysis of this novel transporter in cancer cell lines or clinical tumor samples. Increased resistance to mitoxantrone may result from reduced intracellular drug accumulation, altered nuclear/cytoplasmic drug distribution, and alterations in topoisomerase II activity.  (+info)

(3/750) Dose-escalation study of docetaxel in combination with mitoxantrone as first-line treatment in patients with metastatic breast cancer.

PURPOSE: To define the maximum-tolerated dose (MTD) and the dose-limiting toxicities (DLTs) of docetaxel in combination with mitoxantrone in patients with metastatic breast cancer (MBC). PATIENTS AND METHODS: Forty-one chemotherapy-naive patients with MBC (median age, 61 years) were enrolled. Thirty-eight (93%) had performance status (World Health Organization [WHO]) 0, 29 (71%) were postmenopausal, and 21 (51%) had estrogen receptor-negative tumors. Patients received escalated doses of docetaxel (75 to 100 mg/m2) on day 1 and mitoxantrone (8 to 22 mg/m2) on day 8. Treatment was repeated every 3 weeks. RESULTS: A total of 217 chemotherapy cycles were administered. Without recombinant human granulocyte colony-stimulating factor (rhG-CSF) support, the MTD1 occurred at the first dose level (docetaxel 75 mg/m2 and mitoxantrone 8 mg/m2); DLTs were febrile neutropenia, grade 4 neutropenia lasting more than 5 days, and grade 3 diarrhea. With prophylactic rhG-CSF, the MTD2 was docetaxel 100 mg/m2 and mitoxantrone 20 mg/m2; DLTs were febrile neutropenia and grade 4 neutropenia. Nine (22%) patients developed neutropenia after the first cycle of treatment. A total of 19 episodes of febrile neutropenia (9% of the cycles) occurred during the whole period of the study; there were no toxic deaths. At high docetaxel (100 mg/m2) and mitoxantrone (> 12 mg/m2) dose levels, a significant decrease of the absolute lymphocyte number was observed; immunophenotyping revealed that all lymphocyte subpopulations were reduced. Grades 2 and 3 neurosensory toxicity occurred in six patients (15%) and one patient (2%), respectively. No cardiac toxicity was observed. Nine complete responses (22%) and 23 partial responses (56%) were achieved (overall response rate, 78%; 95% confidence interval, 62.5% to 88.8%). The median duration of response was 12.5 months, and the median time to tumor progression was 14.5 months. CONCLUSION: The reported combination of docetaxel and mitoxantrone with G-CSF support is a safe, intensified, well-tolerated, and effective regimen as first-line treatment in patients with MBC.  (+info)

(4/750) Autologous transplantation of chemotherapy-purged PBSC collections from high-risk leukemia patients: a pilot study.

We have recently demonstrated that the combination of the alkylating agent nitrogen mustard (NM) and etoposide (VP-16) is capable of eliminating, ex vivo, leukemic cells contaminating PBSC collections and this is associated with a significant recovery of primitive and committed hematopoietic progenitor cells. Based on these data a pilot study on autologous transplantation of NM/VP-16 purged PBSC for high-risk leukemic patients was recently initiated. Twelve patients (seven females and five males) with a median age of 46 years (range 18-57) have been treated. Two patients had acute myeloblastic leukemia (AML) resistant to conventional induction treatment, four patients had secondary AML in I complete remission (CR), one patient was in II CR after failing a previous autologous BM transplantation, while two additional AML individuals were in I CR achieved after three or more cycles of induction treatment. Two patients with high-risk acute lymphoblastic leukemia (ALL) in I CR and one patient with mantle cell lymphoma and leukemic dissemination were also included. Eight patients showed karyotypic abnormalities associated with a poor clinical outcome. The mobilizing regimens included cytosine arabinoside and mitoxantrone with (n = 6) or without fludarabine (n = 3) followed by subcutaneous administration of G-CSF (5 microg/kg/day until the completion of PBSC collection) and G-CSF alone (n = 3) (15 microg/kg/day). A median of two aphereses (range 1-3) allowed the collection of 7.2 x 10(8) TNC/kg (range 3.4-11.5), 5 x 10(6) CD34+ cells/kg (range 2.1-15.3) and 9.2 x 10(4) CFU-GM/kg (0.3-236). PBSC were treated with a constant dose of 20 microg of VP-16/ml and a median individual-adjusted dose (survival < or = 5% of steady-state BM CFU-GM) of NM of 0.7 microg/ml (range 0.25-1.25). Eleven patients were reinfused after busulfan (16 mg/kg) and Cy (120 mg/kg) conditioning with a median residual dose of 0.3 x 10(4) CFU-GM/kg (0-11.5). The median time to neutrophil engraftment (>0.5 x 10(9)/l) for evaluable patients was 25 days (range 12-59); the median time to platelet transfusion independence (>20 and >50 x 10(9)/l) was 40 days (18-95) and 69 days (29-235), respectively. Hospital discharge occurred at a median of 25 days (18-58) after stem cell reinfusion. Four individuals are alive in CR (n = 3) or with residual nodal disease (n = 1 lymphoma patient) with a follow-up of 32, 26, 3 and 14 months, respectively. Seven patients died due to disease progression or relapse (n = 5) or extrahematological transplant toxicity (n = 2). Our data suggest that pharmacological purging of leukapheresis collections of leukemic patients at high-risk of relapse is feasible and ex vivo treated cells reconstitute autologous hematopoiesis.  (+info)

(5/750) Follicular large cell lymphoma: an aggressive lymphoma that often presents with favorable prognostic features.

It is debated whether follicular large cell lymphoma (FLCL) has a clinical behavior that is distinct from indolent follicular lymphomas, and whether there is a subset of patients who can be potentially cured. We report here our experience with 100 FLCL patients treated at our institution since 1984 with three successive programs. We evaluated the predictive value of pretreatment clinical features, including two risk models, the Tumor Score System and the International Prognostic Index (IPI). With a median follow-up of 67 months, the 5-year survival is 72% and the failure-free survival (FFS) is 67%, with a possible plateau in the FFS curve, particularly for patients with stage I-III disease. Features associated with shorter survival included age >/=60, elevated lactic dehydrogenase (LDH) or beta-2-microglobulin (beta2M), advanced stage, and bone marrow involvement. Stage III patients had significantly better survival than stage IV patients (P <.05). By the IPI and Tumor Score System, 80% of the patients were in the lower risk groups; both systems stratified patients into prognostic groups. Patients with FLCL have clinical features and response to treatment similar to that reported for diffuse large cell lymphoma. Prognostic risk systems for aggressive lymphomas are useful for FLCL. A meaningful fraction of patients may possibly be cured when treated as aggressive lymphomas.  (+info)

(6/750) Early detection of anthracycline induced cardiotoxicity in asymptomatic patients with normal left ventricular systolic function: autonomic versus echocardiographic variables.

OBJECTIVE: To investigate left ventricular dysfunction in patients who had been treated with anthracycline based chemotherapy. METHODS: Autonomic function was compared with left ventricular diastolic function in 20 asymptomatic women with normal systolic function (left ventricular ejection fraction (LVEF) > 0.50) treated for breast cancer with high dose anthracycline based chemotherapy, and 20 age matched healthy controls. Left ventricular diastolic function was assessed echocardiographically by measuring the early peak flow velocity to atrial peak flow velocity ratio, isovolumic relaxation time, and deceleration time. Heart rate variability analysis was assessed for time domain and frequency domain parameters. RESULTS: The mean (SD) age of the patients was 45 (7) years and the mean LVEF was 0.59 (0.06). The time interval after the end of chemotherapy was 29 (27) months. One or more diastolic variables were abnormal in 50% of the patients. Heart rate variability was abnormal in 85% of patients. Mean values of both time domain and frequency domain parameters were decreased (p < 0.05), in particular the parasympathetic indices. CONCLUSIONS: Autonomic impairment occurs in a large proportion of asymptomatic patients with normal systolic left ventricular function after high dose anthracycline based chemotherapy. In particular, heart rate variability analysis may be a sensitive tool to identify the first signs of cardiotoxicity in these patients.  (+info)

(7/750) Time sequential chemotherapy for primary refractory or relapsed adult acute myeloid leukemia: results of the phase II Gemia protocol.

BACKGROUND AND OBJECTIVE: High-dose cytarabine (HDAra-C), mitoxantrone and etoposide are the mainstay of several active regimens against relapsed or refractory acute myelogenous leukemia (AML). We designed a phase II study to assess the efficacy and side effects of a time sequential application of mitoxantrone plus intermediate-dose Ara-C followed by HDAra-C plus etoposide (GEMIA) in adult patients with refractory or relapsed AML. DESIGN AND METHODS: Patients with refractory or relapsed AML were eligible for GEMIA salvage therapy, which comprised mitoxantrone 12 mg/m2/day on days 1-3, Ara-C 500 mg/m2/day as a 24-hour continuous infusion on days 1-3, followed by HDAra-C 2 g/m2/12-hourly on days 6-8 and etoposide 100 mg/m2/12-hourly on days 6-8. Granulocyte colony-stimulating factor was started on day 14. In patients above the age of 55 the dose of Ara-C in the first sequence (days 1-3) was reduced to 250 mg/m2. RESULTS: Twenty patients were included, of whom 12 achieved complete remission after GEMIA (60%, 95% CI 40-80%), one was refractory and five died early from infection. Two additional patients achieved partial remission after GEMIA and complete remission after consolidation chemotherapy, for a final CR rate of 70% (95% CI 48-88%). Neutrophils recovered at a median of 27 days (range, 22-43) and platelets 46 days (range, 25-59) after the start of treatment. The median duration of remission was 133 days (range, 36-417+) whereas overall survival time lasted for a median of 153 days (range, 13-554+). Treatment-associated toxicity was comprised predominantly of infection, mucositis and diarrhea that reached World Health Organization grades III-V in 40%, 40% and 30% of patients, respectively. Despite the intention to rapidly proceed to a hematopoietic stem cell transplant in patients in remission, only five patients reached the transplant. INTERPRETATION AND CONCLUSIONS: The GEMIA time sequential chemotherapy regimen appears effective in obtaining remissions in refractory and relapsed adult AML. The high toxicity seen, however, suggests that its design is amenable to further improvements, especially in more elderly patients. Since remissions are short-lived, more innovative post-remission strategies are needed.  (+info)

(8/750) Trisomy 21 associated transient neonatal myeloproliferation in the absence of Down's syndrome.

Although usually associated with Down's syndrome, transient neonatal myeloproliferation (TMD) can occur in the absence of a constitutional trisomy 21. This report describes two such cases, both of whom had a trisomy 21 restricted to clonal cells. Unlike in previous such reported cases, spontaneous morphological, cytogenetic, and molecular remission in both cases was followed by re-emergence, in one case, of an evolved clone with a more malignant phenotype which required pharmacological intervention. Awareness that trisomy 21 bearing leukaemia in the neonatal period can be transient even in the absence of Down's syndrome is important to prevent unnecessary treatment. Equally, such cases require indefinite follow up as a proportion may have a recurrence which may require treatment.  (+info)