Phthalascidin, a synthetic antitumor agent with potency and mode of action comparable to ecteinascidin 743.
(25/8107)
A series of totally synthetic molecules that are structurally related to the marine natural product ecteinascidin 743 (Et 743) has been prepared and evaluated as antitumor agents. The most active of these, phthalascidin, is very similar to Et 743 with regard to in vitro potency and mode of action across a variety of cell types. The antiproliferative activity of phthalascidin (IC50 = 0.1-1 nM) is greater than that of the agents Taxol, camptothecin, adriamycin, mitomycin C, cisplatin, bleomycin, and etoposide by 1-3 orders of magnitude, and the mechanism of action is clearly different from these currently used drugs. Phthalascidin and Et 743 induce DNA-protein cross-linking and, although they seem to interact with topoisomerase (topo) I (but not topo II), topo I may not be the primary protein target of these agents. Phthalascidin and Et 743 show undiminished potency in camptothecin- and etoposide-resistant cells. Phthalascidin is more readily synthesized and more stable than Et 743, which is currently undergoing clinical trials. The relationship of chemical structure and antitumor activity for this class of molecules has been clarified by this study. (+info)
Spontaneous gastrointestinal perforation in patients with lymphoma receiving chemotherapy and steroids. Report of three cases.
(26/8107)
Spontaneous gastrointestinal perforations in three patients with lymphoma were considered to be treatment-related conditions. All three were diagnosed as having malignant lymphoma by histological examination, and treated with chemotherapy and steroids. Four to 14 days after the start of chemotherapy, they complained of abdominal pain and plain roentgenograms revealed pneumoperitoneum. The interval between the onset of peritonitis and operation was almost 24 h. Emergency operations were carried out; one patient with a jejunal perforation underwent resection of the jejunum, another with a gastric perforation received a simple closure with omental patch, and the third with a gastric perforation underwent gastrectomy. Two patients recovered from the surgery, while the gastrectomy patient died due to sepsis. The favorable outcome of the surgical intervention is attributed to early diagnosis, prompt exploration, and selective operative procedures. We recommended a simple closure with omental patch for gastroduodenal perforation. Resection and primary anastomosis are possible only in the small bowel. (+info)
Selective inhibition of MDR1 P-glycoprotein-mediated transport by the acridone carboxamide derivative GG918.
(27/8107)
The acridone carboxamide derivative GG918 (N-{4-[2-(1,2,3,4-tetrahydro-6,7-dimethoxy-2-isoquinolinyl)-ethyl]-pheny l}-9,10dihydro-5-methoxy-9-oxo-4-acridine carboxamide) is a potent inhibitor of MDR1 P-glycoprotein-mediated multidrug resistance. Direct measurements of ATP-dependent MDR1 P-glycoprotein-mediated transport in plasma membrane vesicles from human and rat hepatocyte canalicular membranes indicated 50% inhibition at GG918 concentrations between 8 nM and 80 nM using N-pentyl-[3H]quinidinium, ['4C]doxorubicin and [3H]daunorubicin as substrates. The inhibition constant K for GG918 was 35 nM in rat hepatocyte canalicular membrane vesicles with [3H]daunorubicin as the substrate. Photoaffinity labelling of canalicular and recombinant rat Mdr1b P-glycoprotein by [3H]azidopine was suppressed by 10 muM and 40 muM GG918. The high selectivity of GG918-induced inhibition was demonstrated in canalicular membrane vesicles and by analysis of the hepatobiliary elimination in rats using [3H]daunorubicin, [3H]taurocholate and [3H]cysteinyl leukotrienes as substrates for three distinct ATP-dependent export pumps. Almost complete inhibition of [3H]daunorubicin transport was observed at GG918 concentrations that did not affect the other hepatocyte canalicular export pumps. The high potency and selectivity of GG918 for the inhibition of human MDR1 and rat Mdr1b P-glycoprotein may serve to interfere with this type of multidrug resistance and provides a tool for studies on the function of these ATP-dependent transport proteins. (+info)
Delivery of methoxymorpholinyl doxorubicin by interleukin 2-activated NK cells: effect in mice bearing hepatic metastases.
(28/8107)
The possibility of using interleukin 2 (IL-2)-activated natural killer cells (A-NK) to carry methoxymorpholinyl doxorubicin (MMDX; PNU 152243) to liver-infiltrating tumours was explored in mice bearing 2-day established M5076 reticulum cell sarcoma hepatic metastases. In vitro, MMDX was 5.5-fold more potent than doxorubicin against M5076 tumour cells. MMDX uptake by A-NK cells correlated linearly with drug concentration in the incubation medium [correlation coefficient (r) = 0.999]; furthermore, as MMDX incorporation was readily reproducible in different experiments, the amount of drug delivered by A-NK cells could be modulated. In vivo experiments showed that intravenous (i.v.) injection of MMDX-loaded A-NK cells exerted a greater therapeutic effect than equivalent or even higher doses of free drug. The increase in lifespan (ILS) following A-NK cell delivery of 53 microg kg(-1) MMDX, a dosage that is ineffective when administered in free form, was similar to that observed in response to 92 microg kg(-1) free drug, a dosage close to the 10% lethal dose (ILS 42% vs. 38% respectively). These results correlated with pharmacokinetic studies showing that MMDX encapsulation in A-NK cells strongly modifies its organ distribution and targets it to tissues in which IL-2 activated lymphocytes are preferentially entrapped after i.v. injection. (+info)
Ifosfamide in combination with paclitaxel or doxorubicin: regimens which effectively mobilize peripheral blood progenitor cells while demonstrating anti-tumor activity in patients with metastatic breast cancer.
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For patients with metastatic breast cancer (MBC) who undergo high-dose therapy with autologous peripheral blood progenitor cell (PBPC) transplantation, an important prerequisite is a mobilization regimen that efficiently mobilizes PBPCs while producing an effective anti-tumor effect. We prospectively evaluated ifosfamide-based chemotherapy for mobilization efficiency, toxicity and disease response in 37 patients. Patients received two cycles of the ifosfamide-based regimen; ifosfamide (5 g/m2 with conventional-dose cycle and 6 g/m2 with mobilization cycle) with either 50 mg/m2 doxorubicin (if limited prior anthracycline and/or progression more than 12 months after an anthracycline-based regimen) or 175 mg/m2 paclitaxel. For the mobilization cycle, all patients received additional G-CSF (10 microg/kg SC, daily) commencing 24 h after completion of chemotherapy. The target yield was >6x10(6) CD34+ cells/kg, sufficient to support the subsequent three cycles of high-dose therapy. The mobilization therapy was well tolerated and the peak days for peripheral blood (PB) CD34+ cells were days 10-13 with no significant differences in the PB CD34+ cells mobilization kinetics between the ifosfamide-doxorubicin vs. ifosfamide-paclitaxel regimens. The median PBPC CD34+ cell content ranged from 2.9 to 4.0x10(6)/kg per day during days 9-14. After a median of 3 (range 1-5) collection days, the median total CD34+ cell, CFU-GM and MNC for all 44 individual sets of collections was 9.2x10(6)/kg (range 0.16-54.9), 37x10(4)/kg (range 5.7-247) and 7.3x10(8)/kg (range 2.1-26.1), respectively. The PBPC target yield was achieved in 35 of the 37 patients. The overall response rate for the 31 evaluable patients was 68% with 10% having progressive disease. Thirty-three patients have subsequently received high-dose therapy consisting of three planned cycles of high-dose ifosfamide, thiotepa and paclitaxel with each cycle supported with PBPCs. Rapid neutrophil and platelet recovery has been observed. Ifosfamide with G-CSF in combination with doxorubicin or paclitaxel achieves effective mobilization of PBPC and anti-tumor activity with minimal toxicity. (+info)
Induction therapy with vincristine, adriamycin, dexamethasone (VAD) and intermediate-dose melphalan (IDM) followed by autologous or allogeneic stem cell transplantation in newly diagnosed multiple myeloma.
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We performed a phase II study to test the efficacy and feasibility of induction therapy with vincristine, adriamycin and dexamethasone (VAD) and intermediate-dose melphalan, 70 mg/m2 (IDM), to autologous or allogeneic stem cell transplantation in newly diagnosed multiple myeloma (MM). A total of 77 patients received two cycles of VAD (n = 62) and/or two cycles of i.v. IDM 70 mg/m2 (n = 15) combined with G-CSF. PBSC were harvested after the first IDM, successfully in 87% of patients. Patients with a response to induction received myeloablative therapy with PBSCT (n = 50) followed by IFN maintenance or allo-BMT (n = 11). Seventy-two per cent of patients achieved a response after VAD which increased to 85% after IDM. Of patients who received PBSCT and allo-BMT, 24% and 45% achieved CR, respectively. Toxicity of induction consisted mainly of bone marrow suppression after IDM (median 8 days) with prolonged aplasia in 11% of patients after the second IDM. Only six infections WHO grade 3 occurred during induction. Treatment-related mortality of PBSCT and allo-BMT was 6% and 18%, respectively. Median time of follow-up is 44 months, and 50% of patients after PBSCT and 60% of patients after allo-BMT are still in remission. Survival rates of all patients were 82%, 75% and 63%, and for transplanted patients 86%, 79% and 68% after 12, 24 and 36 months. Well known prognostic factors, including alpha-IFN maintenance after PBSCT, were not significant for response or survival although patients in CR after allo-BMT had a strong tendency for better outcome. VAD/IDM is an effective and safe induction therapy for autologous and allogeneic stem cell transplantation. Based on these observations a phase III trial was started in October 1995 comparing IFN maintenance with PBSCT and allo-BMT after response to induction with VAD and IDM. (+info)
Enhancement of antitumor activity of polyethylene glycol-coated liposomal doxorubicin with soluble and liposomal interleukin 2.
(31/8107)
Polyethylene glycol-coated liposomal doxorubicin (Doxil) has a sustained release profile and a mild myelosuppressive effect that may enable a beneficial interaction with lymphocyte-activating cytokines, such as interleukin 2 (IL-2). Previous studies have shown that liposome entrapment of IL-2 potentiates its immunomodulatory effects and reduces the need for frequent dosing. We assessed the therapeutic effect of Doxil (8 mg/kg) followed by free or liposomal IL-2 (50,000 Cetus Units x 3) in mice bearing M109 lung adenocarcinoma transplanted i.v. or i.p. Doxil was always administered i.v., whereas IL-2 was given i.v. in the i.v. M109 model and i.p. in the i.p. M109 model. The optimal combined treatment was significantly more effective than liposomal chemotherapy alone, producing tumor-free, long-term survivors in 100% (i.v. M109) and 94% (i.p. M109) of the mice, compared with 50% and 56%, respectively, for Doxil alone. The efficacy boost of IL-2 appeared to be formulation dependent, with free IL-2 and IL-2 in small unilamellar vesicles most active in the i.v. tumor model, and IL-2 in multilamellar vesicles most active in the i.p. tumor model. The combination of Doxil with free or liposomal IL-2 was devoid of any conspicuous toxicity. Cytokine treatment without chemotherapy was completely ineffective. Liposome-based chemoimmunotherapy is a synergistic and highly efficacious approach to eradicate metastatic and regionally spread tumors. (+info)
Effects of human cytomegalovirus immediate-early proteins on p53-mediated apoptosis in coronary artery smooth muscle cells.
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BACKGROUND: Restenotic and atherosclerotic lesions often contain smooth muscle cells (SMCs), which display high rates of proliferation and apoptosis. Human cytomegalovirus (HCMV) may increase the incidence of restenosis and predispose to atherosclerosis. Although the mechanisms contributing to these processes are unclear, studies demonstrate that one of the immediate-early (IE) gene products of HCMV, IE2-84, binds to and inhibits p53 transcriptional activity. Given the role of p53 in mediating apoptosis, we studied the ability of IE2-84 to inhibit p53-dependent apoptosis in human coronary artery SMCs. METHODS AND RESULTS: Apoptosis of SMCs was induced either by use of an adenovirus vector encoding human wild-type p53 protein or by treatment with doxorubicin. HCMV IE1-72 and IE2-84, the major IE proteins of HCMV, were overexpressed separately with adenovirus vectors encoding each protein, and the effects on p53-induced apoptosis were examined by both nick end-labeling (TUNEL) assay and flow cytometry. Expression of IE2-84, but not IE1-72, protected SMCs from p53-mediated apoptosis. CONCLUSIONS: These data indicate that an HCMV IE protein antagonizes p53-mediated apoptosis, suggesting a pathway by which HCMV infection predisposes to SMC accumulation and thereby contributes to restenosis and atherosclerosis. (+info)