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PubMed1990

Modulation of cytotoxicity of cytostatic drugs by hemodialysis in vitro and in vivo.

For most cytotoxic substances there are no established guidelines on how to deal with overdosage. Little is known about the dialysability of cytostatic drugs. To obtain further information, human plasma was incubated with cytostatic drugs and dialysed in vitro, using 'minimodules' with capillaries identical to those in clinical use. Cytotoxicity before and after dialysis was measured in a biological test system using permanent human lymphoblast cultures (LS2). The 20 cytostatic drugs studied were categorized as follows: (1) Dialysability in vitro. Good: methotrexate (MTX), 5-fluorouracil (5-FU/5-FUdR), cytarabine (ARAC), actinomycin D (DACT), mitomycin C (MMC), 4-OH-cyclophosphamide (4-OH-CPM), ifosfamide (IFO), melphalan (L-PAM), dacarbazine (DTIC), cisplatin (DDP). Intermediate: Adriamycin (ADM), 4'-epi-doxorubicin (4'-EA), carmustine (BCNU). Ineffective: daunorubicin (DNR), vincristine (VCR), vinblastine (VBL), vindesine (VDS), etoposide (VP-16), teniposide (VM-26), mitoxantrone (MITOX). These in vitro results cannot be transferred automatically into the in vivo situation because of specific drug distribution and metabolic rates. Considering pharmacokinetic data from the literature, the following recommendations can be made for practical clinical purposes. (2) Detoxification by hemodialysis in vivo. Possibly effective: MTX, 5-FU, MMC, CPM, IFO, L-PAM, BCNU, DTIC. Ineffective: ADM, 4'-EA, DNR, MITOX, DACT, VP-16, VM-26, VCR, VBL, VDS, ARAC, DDP.

Antineoplastic Agents↗
PubMed1995

High-dose chemotherapy regimens for solid tumors.

High-dose chemotherapy with blood progenitor cell transplantation is increasingly recognized as a potentially valuable treatment for breast cancer, germ cell cancer, ovarian cancer and other solid tumors. A variety of cytotoxic drugs, particularly alkylating agents, have been investigated either alone or in combinations. Current, predominantly small, phase I and phase II clinical trials to not adequately compare the efficacy of these regiments and patterns of dose-limiting extramedullary toxicity are emerging. Busulfan, carmustine (BCNU) and mitomycin C cause veno-occlusive disease (VOD) of the liver in some patients and the latter two agents also cause interstitial pneumonitis. Cisplatin and ifosfamide only allow minor dose escalation before renal failure becomes prohibitive. Cyclophosphamide, thiotepa, melphalan and etoposide allow substantial dose escalation above standard and are mainly associated with mucositis. Moderate dose escalations of mitoxantrone and carboplatin are possible, limited by cardiotoxicity and neurotoxicity, respectively. Advances in supportive care have abolished bone marrow suppression as the dose-limiting toxicity in chemotherapy. Severe and potentially fatal extramedullary toxicity following high-dose chemotherapy can only be avoided by administering agents with predictable toxicity patterns and by carefully considering their clinical pharmacology.

Antineoplastic Agents↗
PubMed1990

Enhanced DNA repair and tolerance of DNA damage associated with resistance to cis-diammine-dichloroplatinum (II) after in vitro exposure of a human teratoma cell line to fractionated X-irradiation.

In vitro exposure of a human testicular teratoma continuous cell line to fractionated X-irradiation resulted in the expression of resistance to cisplatin. In two independently-derived sublines, designated SUSA-DXR13 and SUSA-DXR10 resulting from treatment with either 13 fractions of 1.5 Gy (dose required to reduce survival by 1 log) or 10 fractions of 3 Gy (dose required to reduce survival by 2 logs) respectively, the IC50 values for cisplatin were 2- and 3.1-fold higher than that of the parental cell line. These sublines were cross-resistant to carboplatin (approximately 2-fold) but not to adriamycin and they showed unaltered radiosensitivities. The SUSA-DXR10 subline expressed some cross-resistance to mitomycin C and melphalan but none to Carmustine (BCNU). Total glutathione content was significantly reduced in both SUSA-DXR10 and SUSA-DXR13 cells, but the activities of associated enzymes, including the glutathione S-transferases, peroxidase and reductase were not modified significantly in the resistant sublines. Resistance in the SUSA-DXR10 subline was associated with significantly decreased 195mcisplatin uptake (p less than 0.01), but this was not reflected in a reduced level of drug bound to the DNA. The formation and removal of four platinum-DNA adducts were immunochemically quantitated. Immediately following drug treatment there was a higher level of total platination of the DNA in the resistant subline indicative of increased tolerance to DNA damage. After an 18 hr post treatment incubation, there was an indication of some repair capacity in this SUSA-DXR10 cell line, which was not apparent in the parental cells. Neither the parental nor the SUSA-DXR10 cell line was proficient in the repair of the major adduct Pt-GG, whereas both lines repaired the monofunctional adduct and the adduct Pt(GMP)2. SUSA-DXR10 cells were also able to repair the intrastrand adduct Pt-AG and interstrand crosslinks, unlike the repair deficient parental cells. Higher levels of interstrand crosslinks were characteristic of the SUSA-DXR10 subline. These observations therefore implicate both enhanced repair and increased tolerance of DNA damage as mechanisms of resistance to cisplatin resulting from in vitro exposure of a human teratoma cell line to fractionated X-irradiation.

Cisplatin↗
PubMed1994

Patterns of failure of complete responders following high-dose chemotherapy and autologous bone marrow transplantation for metastatic breast cancer: implications for the use of adjuvant radiation therapy.

PURPOSE: To determine the pattern of failure and outcome of patients achieving a complete response following high-dose chemotherapy and autologous bone marrow transplantation for metastatic breast cancer, and to evaluate the use of involved field radiation therapy in this setting. METHODS AND MATERIALS: Thirty-one patients with metastatic breast cancer treated on three successive high-dose chemotherapy and autologous bone marrow transplantation trials between January 1987 and March 1992 who achieved a complete response were evaluated. Twenty-three patients (74.2%) had initially Stage I-II disease. Initial therapy consisted of mastectomy in 19 (74.2%), adjuvant chemotherapy in 19 (61.3%), and adjuvant radiation therapy in 11 (35.5%). All patients underwent induction chemotherapy prior to high-dose intensification. High-dose chemotherapy consisted of cytoxan, thiotepa +/- carmustine. Fourteen patients received radiation therapy prior to (7) or following the high-dose chemotherapy (7) with either the intent to palliate a symptomatic disease site (4) or to attain/maintain a complete response (10). The four palliatively treated sites received 30 Gy in 3.0 Gy fractions, the sites treated definitively received a mean dose of 43.9 Gy (range, 18-64.8 Gy) in 1.5-2.0 Gy fractions. Seventy-two disease sites were present in the 31 patients. The most common sites involved were nodal (23), bone (14), and chest wall/breast (11). Nineteen sites were bulky (> 2 cm in size). Twenty-three sites were irradiated (19 definitively, 4 palliatively). Median follow-up was 18 months (range, 2-49 months). RESULTS: Twenty (64.5%) of the 31 patients relapsed. Eleven of the 17 patients not receiving radiation failed. Seven (63.6%) failed first solely in sites of previous disease involvement and four (36.4%) failed in new sites. This failure pattern was reversed in the patients receiving radiation therapy. Nine of the 14 (64.3%) patients relapsed. Two (22.2%) failed solely in old sites and six (66.7%) solely in new sites. One patient (11.1%) failed simultaneously in both old and new sites. Patients receiving radiation therapy had a similar 2-year actuarial disease-free survival compared to those not treated with radiation (28.3% vs. 32.1%) (p = 0.14). However, patients with less than three sites of disease had a better disease-free survival at 2 years with the addition of radiation therapy (30.0% vs. 17.6%) (p = 0.03). Patients with locoregional disease only had a lower rate of local failure (one out of four vs. three out of five) and a longer mean time to any failure (4.0 months vs. 17.5 months) with the addition of radiation therapy. Of the 72 sites identified, 59 (81.9%) were amenable to radiation therapy either prior to or following the transplant. The use of radiation therapy resulted in a borderline significant improvement in 2-year actuarial control of all sites (82.4% vs. 64.3%) (p = 0.09) as well as of bulky sites (80.0% vs. 51.4%) (p = 0.08). Excluding the four sites treated with palliative intent only, the 2-year actuarial local control of the irradiated sites was 92.8%. None of the 14 treated patients experienced untoward sequelae. CONCLUSION: The predominant site of initial failure in patients with metastatic breast cancer achieving a complete response following high-dose chemotherapy and autologous bone marrow transplantation is in sites of previous disease involvement. Radiation therapy given in conjunction with the high-dose chemotherapy is capable of improving the control of these sites, the majority of which are amenable to treatment with radiation therapy. Our data suggests that patients with less than three sites of disease, bulky disease, and locoregional disease only should be considered for radiation therapy in addition to high-dose chemotherapy.

Adult↗
PubMed1992

Cholesterol and mevalonic acid modulation in cell metabolism and multiplication.

Cholesterol in animals is a major structural component of cell membranes. It may therefore play a functional role in the modulation of cell osmolarity, the process of pinocytosis and the activities of membrane-associated proteins such as ionic pumps, immune responses, etc. A major relationship exists between the cell-growth processes and the cholesterol biosynthetic pathway. The cholesterol needed for new membranes may be derived either from endogenous synthesis or from exogenous sources, principally plasma low-density-lipoproteins (LDL) which enter the cells by receptor-mediated endocytosis. Both these pathways are enhanced in rapidly growing cells. Conversely, if synthesis is inhibited and no exogenous cholesterol is available, cell growth is blocked. The 3-hydroxy-3-methylglutaryl CoA (HMGCoA) reductase (the rate-limiting reaction in cholesterol biosynthesis) is the enzyme which catalyzes the conversion of HMGCoA to mevalonic acid. It has been suggested that mevalonate may play an important role in cell proliferation. All cells need at least two products synthesized from mevalonate in order to proliferate, and the only one yet identified is cholesterol. Other melavonate-derived potential candidates as cell-cycle and cell-survival products include the dolichols ubiquinone side chains, isopentenyladenosine derivatives, etc. Furthermore, it has recently been shown that membrane association appears to be an important function in mevalonate-derive modifications of several important proteins such as cellular membrane G proteins, those coded for by oncogenes (ras proteins) and lamins (nuclear proteins). In recent years the development of cholesterol-synthesis-inhibiting drugs, for lowering plasma cholesterol levels has mainly been centred on the control of HMGCoA reductase activity (vastatins). However, because mevalonic acid is the precursor of numerous metabolites, any reduction of such activity may potentiate pleiotropic effects. Vastatins are now, therefore, receiving increased attention as potential pharmacological tools for the control of abnormal cell growth in pathological situations, i.e. tumours and vascular smooth muscle cell proliferation under atherogenic conditions. In our laboratories, we have demonstrated that simvastatin can prevent arterial myocyte proliferation both in vivo and in vitro. Simvastatin can also inhibit in vitro the rate of human glioma cell growth, since it shows a strong synergistic inhibitory effect on cell proliferation when used in association with anticancer agents such as Carmustine or beta-interferon. Both simvastatin-induced cell growth inhibition and the synergy observed with these drugs can be completely reversed by incubating cells with mevalonate. This shows that the effect of simvastatin of cell proliferation is due to its specific inhibitory activity on intracellular mevalonate synthesis.

Animals↗
PubMed1995

Combination of computerized morphonuclear and multivariate analyses to characterize in vitro the antineoplastic effect of alkylating agents.

The influence of 13 anticancer alkylating agents on cell proliferation, cell cycle parameters, and morphonuclear characteristics was monitored in vitro on three neoplastic cell lines. This monitoring was carried out by means of the digital cell image analysis of Feulgen-stained nuclei. This computer-assisted microscope analysis of chromatin texture made it possible to assess 15 morphonuclear parameters. These 15 parameters were submitted to multivariate analyses, that is, principal-components analyses followed by the canonical transformation of the data. The 13 alkylating agents included four nitrogen mustards (chlormethine, chlorambucil, melphalan, and cyclophosphamide), two nitrosoureas (carmustine and lomustine), two platinum analogues (cisplatine and carboplatine), two ethyleneimine derivatives (thiotepa and investigational PE1001), one antibiotic (mitomycin C), one alkylsulfonate (busulfan), and one triazene (dacarbazine). The mouse MXT mammary and the human J82 and T24 bladder tumor cell lines were used in this study. The results show that these alkylating agents induced specific modifications to the chromatin pattern according to the subclass to which they belong. In other words, the multivariate statistical analyses of the 15 parameters made it possible to identify, at least partly, distinct subclasses of alkylating agents according to their mechanisms of action. As a validation of the methodology, the results also show that most of the alkylating agents induced an increase in the percentage of cells in the G2 phase, while some sometimes induced an increase in the percentage of cells in the S phase of the cell cycle.

Adenocarcinoma↗
PubMed2006

Consolidation with high-dose combination alkylating agents with bone marrow transplantation significantly improves disease-free survival in hormone-insensitive metastatic breast cancer in complete remission compared with intensive standard-dose chemotherapy alone.

We conducted this study to determine event-free and overall survival among women with hormone-insensitive or hormone-resistant metastatic breast cancer receiving consolidation with high-dose chemotherapy (HDC) and hematopoietic support versus no further chemotherapy after intensive induction chemotherapy. Eligible patients received induction doxorubicin, 5-fluorouracil, and methotrexate (AFM) for 2 to 4 cycles. Women in complete remission were randomized to immediate HDC with cyclophosphamide, cisplatin, and carmustine followed by autologous hematopoietic support or to no further therapy. Patients on the observation arm of therapy were offered salvage HDC at the time of relapse. Partial responders to AFM were offered immediate HDC. A total of 425 patients were enrolled onto the study. The median event-free survival for women randomized to induction therapy alone was 3.8 months, compared with 9.7 months for women who completed HDC (P < .006). Of the patients randomized to observation, 5 (10%) of 51 remain event free, compared with 13 (26%) of 49 patients who underwent immediate HDC (P = .03). Of women converted to a complete response by salvage HDC after a partial response to AFM, overall survival was similar to that in women randomized to immediate HDC. Follow-up is now in excess of 5 years. The 5-year event-free survival is 15% (95% confidence interval, 12%-18%), and the 5-year overall survival is 20% (95% confidence interval, 17%-25%). Immediate HDC after a complete response to AFM produced some durable long-term responses in hormone-insensitive/-resistant metastatic breast cancer. Salvage HDC converted 30% of partial responders to complete responders with similar survivals. The addition of novel targeted therapies to intensive-dose chemotherapy regimens may further improve survival in metastatic breast cancer.

Adult↗
PubMed2006

Cellular disulfide-reducing capacity: an integrated measure of cell redox capacity.

To assess the disulfide reduction capacity of intact cells, EA.hy926 endothelial cells were incubated with alpha-lipoic acid in the presence of 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB). Alpha-lipoic acid was reduced within cells to dihydrolipoic acid, which could be quantified upon efflux from the cells as reduction of DTNB. Uptake of both alpha-lipoic acid and alpha-lipoamide occurred at least in part via a medium chain fatty acid transporter, based on inhibition by octanoate. Alpha-lipoic acid was reduced within cells by pyridine nucleotide-disulfide oxidoreductases, since it is not reduced by GSH and since its reduction was inhibited by carmustine. Nonetheless, reduction was also dependent on the cellular redox environment, since it was inhibited by the redox cycling of menadione, by decreasing intracellular GSH, and by reduction of dehydroascorbate. Together, these results show that alpha-lipoic acid-dependent DTNB reduction provides a simple method to assess the disulfide-reducing capacity of intact cells, especially as determined by pyridine nucleotide-disulfide oxidoreductases.

Cell Line↗
PubMedDate not supplied

Current management strategies for cutaneous T-cell lymphoma.

Cutaneous T-Cell Lymphoma is a group of lymphomas characterized by a malignant proliferation of skin homing T cells. Prognosis is generally good and treatment is based on the stage of the disease with the goal of inducing remission. Patients with disease limited to the skin in the form of patches and plaques respond best to "skin directed therapy" with topical agents including corticosteroids, nitrogen mustard, carmustine, bexarotene gel, as well as phototherapy with ultraviolet B light, PUVA, or photodynamic therapy. Tazarotene and imiquimod show potential in the treatment of early CTCL. Patients with disease resistant to treatment or with advanced disease require more aggressive therapy in the form of total skin electron beam radiation, biologic response modifiers including interferon alpha, bexarotene, denileukin diftitox, extracorporeal photochemotherapy or combination therapy. The use of chemotherapy is used primarily for palliation. Allogeneic hematopoetic stem cell transplantation may represent a successful treatment for treatment resistant disease.

Administration, Topical↗
PubMed2004

Alkylation damage in DNA and RNA--repair mechanisms and medical significance.

Alkylation lesions in DNA and RNA result from endogenous compounds, environmental agents and alkylating drugs. Simple methylating agents, e.g. methylnitrosourea, tobacco-specific nitrosamines and drugs like temozolomide or streptozotocin, form adducts at N- and O-atoms in DNA bases. These lesions are mainly repaired by direct base repair, base excision repair, and to some extent by nucleotide excision repair (NER). The identified carcinogenicity of O(6)-methylguanine (O(6)-meG) is largely caused by its miscoding properties. Mutations from this lesion are prevented by O(6)-alkylG-DNA alkyltransferase (MGMT or AGT) that repairs the base in one step. However, the genotoxicity and cytotoxicity of O(6)-meG is mainly due to recognition of O(6)-meG/T (or C) mispairs by the mismatch repair system (MMR) and induction of futile repair cycles, eventually resulting in cytotoxic double-strand breaks. Therefore, inactivation of the MMR system in an AGT-defective background causes resistance to the killing effects of O(6)-alkylating agents, but not to the mutagenic effect. Bifunctional alkylating agents, such as chlorambucil or carmustine (BCNU), are commonly used anti-cancer drugs. DNA lesions caused by these agents are complex and require complex repair mechanisms. Thus, primary chloroethyl adducts at O(6)-G are repaired by AGT, while the secondary highly cytotoxic interstrand cross-links (ICLs) require nucleotide excision repair factors (e.g. XPF-ERCC1) for incision and homologous recombination to complete repair. Recently, Escherichia coli protein AlkB and human homologues were shown to be oxidative demethylases that repair cytotoxic 1-methyladenine (1-meA) and 3-methylcytosine (3-meC) residues. Numerous AlkB homologues are found in viruses, bacteria and eukaryotes, including eight human homologues (hABH1-8). These have distinct locations in subcellular compartments and their functions are only starting to become understood. Surprisingly, AlkB and hABH3 also repair RNA. An evaluation of the biological effects of environmental mutagens, as well as understanding the mechanism of action and resistance to alkylating drugs require a detailed understanding of DNA repair processes.

AlkB Homolog 1, Histone H2a Dioxygenase↗
PubMed2004

Tributyltin-sulfhydryl interaction as a cause of immunotoxicity in phagocytes of tunicates.

We reported elsewhere that tributyltin (TBT) has detrimental effects on the immune system of the colonial ascidian Botryllus schlosseri, through interaction with calmodulin and alteration of Ca2+ homeostasis. Here, we studied the capability of TBT to react with intracellular thiols. After exposure to 0.1 microM TBT, a significant decrease in B. schlosseri hemocytes stained for total thiols and reduced glutathione (GSH) was detected. Exogenous sulfhydryl and sulfide compounds can prevent TBT-induced cell morphology alterations and decrease the percentage of tin-containing hemocytes, indicating the scavenging ability of thiol peptides. No effects were observed with disulfides, N-acetylcysteine, or the GSH fragment Cys-Gly. No interactions were observed with TBT and carmustine, whereas TBT and N-ethylmaleimide (NEM) showed a combined antagonistic action, suggesting direct interaction of TBT with thiol-containing compounds. Regulation of Ca2+ efflux from internal stores seems to depend on stimulation of the inositol 1,4,5-trisphosphate (InsP3) receptor by oxidized glutathione (GSSG), which results from interactions of both TBT-GSH and TBT-GSH reductase.

Animals↗
PubMed2005

Inhibition of thioredoxin reductase but not of glutathione reductase by the major classes of alkylating and platinum-containing anticancer compounds.

Mammalian thioredoxin reductase (TrxR) is important for cell proliferation, antioxidant defense, and redox signaling. Together with glutathione reductase (GR) it is the main enzyme providing reducing equivalents to many cellular processes. GR and TrxR are flavoproteins of the same enzyme family, but only the latter is a selenoprotein. With the active site containing selenocysteine, TrxR may catalyze reduction of a wide range of substrates, but can at the same time easily be targeted by electrophilic compounds due to the extraordinarily high reactivity of a selenolate moiety. Here we addressed the inhibition of the enzyme by major anticancer alkylating agents and platinum-containing compounds and we compared it to that of GR. We confirmed prior studies suggesting that the nitrosourea carmustine can inhibit both GR and TrxR. We next found, however, that nitrogen mustards (chlorambucil and melphalan) and alkyl sulfonates (busulfan) efficiently inhibited TrxR while these compounds, surprisingly, did not inhibit GR. Inhibitions were concentration and time dependent and apparently irreversible. Anticancer anthracyclines (daunorubicin and doxorubicin) were, in contrast to the alkylating agents, not inhibitors but poor substrates of TrxR. We also found that TrxR, but not GR, was efficiently inhibited by both cisplatin, its monohydrated complex, and oxaliplatin. Carboplatin, in contrast, could not inhibit any of the two enzymes. These findings lead us to conclude that representative compounds of the major classes of clinically used anticancer alkylating agents and most platinum compounds may easily target TrxR, but not GR. The TrxR inhibition should thereby be considered as a factor that may contribute to the cytotoxicity seen upon clinical use of these drugs.

Animals↗
PubMed2005

Primary brain tumors treated with steroids and radiotherapy: low CD4 counts and risk of infection.

PURPOSE: Patients with primary brain tumors are often treated with high doses of corticosteroids for prolonged periods to reduce intracranial swelling and alleviate symptoms such as headaches. This treatment may lead to immunosuppression, placing the patient at risk of life-threatening opportunistic infections, such as Pneumocystis carinii pneumonia. The risk of contracting some types of infection may be reduced with prophylactic antibiotics. The purpose of this study was to determine the occurrence of low CD4 counts and whether monitoring CD4 counts during and after radiotherapy (RT) is warranted. METHODS AND MATERIALS: CD4 counts were measured during RT in 70 of 76 consecutive patients with newly diagnosed Grade III and IV astrocytoma and anaplastic oligodendroglioma treated with corticosteroids and seen at the Johns Hopkins Hospital. Weekly CD4 measurements were taken in the most recent 25 patients. Prophylactic trimethoprim-sulfamethoxazole (160 mg/800 mg p.o. every Monday, Wednesday, and Friday) or dapsone (100 mg p.o. daily) in those with sulfa allergy was prescribed only if patients developed a low CD4 count. Carmustine chemotherapy wafers were placed at surgery in 23% of patients, evenly distributed between the groups. No patient received any other chemotherapy concurrent with RT. RESULTS: CD4 counts decreased to <200/mm3 in 17 (24%) of 70 patients. For the 25 patients with weekly CD4 counts, all CD4 counts were >450/mm3 before RT, but 6 (24%) of 25 fell to <200/mm3 during RT. Patients with counts <200/mm3 were significantly more likely to be hospitalized (41% vs. 9%, p <0.01) and be hospitalized for infection (23% vs. 4%, p <0.05) during RT. Overall survival was not significantly different between the groups. All patients with low CD4 counts were treated with prophylactic antibiotics, and no patient developed Pneumocystis carinii pneumonia. No patients developed a serious adverse reaction to antibiotic therapy. The mean dose of steroids, mean minimal white blood cell count, and number of patients treated with Gliadel wafers were not significantly different between the groups. CONCLUSION: The results of this study have confirmed the clinical impression that the use of high-dose corticosteroids and RT in patients with primary brain cancer is sufficient to result in severe immunosuppression and place these patients at risk of life-threatening opportunistic infections. A protocol of prophylactic antibiotics for those at risk may help prevent a potentially fatal side effect of treatment. A prospective study is underway to determine the frequency, depth, and prognostic implications of this finding.

Adrenal Cortex Hormones↗
PubMed2006

A phase II trial of accelerated radiotherapy using weekly stereotactic conformal boost for supratentorial glioblastoma multiforme: RTOG 0023.

PURPOSE: This phase II trial was performed to assess the feasibility, toxicity, and efficacy of dose-intense accelerated radiation therapy using weekly fractionated stereotactic radiotherapy (FSRT) boost for patients with glioblastoma multiforme (GBM). METHODS AND MATERIALS: Patients with histologically confirmed GBM with postoperative enhancing tumor plus tumor cavity diameter <60 mm were enrolled. A 50-Gy dose of standard radiation therapy (RT) was given in daily 2-Gy fractions. In addition, patients received four FSRT treatments, once weekly, during Weeks 3 to 6. FSRT dosing of either 5 Gy or 7 Gy per fraction was given for a cumulative dose of 70 or 78 Gy in 29 (25 standard RT + 4 FSRT) treatments over 6 weeks. After the RT course, carmustine (BCNU) at 80 mg/m(2) was given for 3 days, every 8 weeks, for 6 cycles. RESULTS: A total of 76 patients were analyzed. Toxicity included: 3 Grade 4 chemotherapy, 3 acute Grade 4 radiotherapy, and 1 Grade 3 late. The median survival time was 12.5 months. No survival difference is seen when compared with the RTOG historical database. Patients with gross total resection (41%) had a median survival time of 16.6 months vs. 12.0 months for historic controls with gross total resection (p = 0.14). CONCLUSION: This first, multi-institutional FSRT boost trial for GBM was feasible and well tolerated. There is no significant survival benefit using this dose-intense RT regimen. Subset analysis revealed a trend toward improved outcome for GTR patients suggesting that patients with minimal disease burden may benefit from this form of accelerated RT.

Adult↗
PubMed2006

Primary brain T-cell lymphoma after kidney transplantation: a case report.

BACKGROUND: Development of primary brain PTLD after kidney transplantation is uncommon, and the incidence of T-cell phenotypes is much more rarely reported in the previous literature. However, prognosis of T-cell PTLD is typically grave, so early diagnosis and treatment are crucial to patient survival. CASE DESCRIPTION: A 60-year-old woman, who had received a kidney transplant 4 years previously, presented with focal seizures and left hemiparesis. She underwent serial diagnostic neuroimaging, which revealed an undefined etiology of an intracerebral tumor. Pathologic biopsy was mandatory. The tumor was grossly removed and its pathology was determined to be monomorphic T-cell lymphoma. No other organ involvement was noted. The patient underwent chemotherapy with a combination of carmustine, oncovin, and methylprednisolone. The patient's neurologic signs, however, deteriorated rapidly, and the patient finally died of neutropenia and septic shock 1 month after chemotherapy. CONCLUSIONS: Development of primary brain T-cell PTLD after kidney transplantation is rare and typically has a grave prognosis, emphasizing the importance of early diagnosis and treatment. This case illustrates that the diagnosis of lymphoma can only be confirmed by pathologic biopsy; however, magnetic resonance imaging, in particular magnetic resonance spectroscopy, is a powerful tool for differential diagnosis.

Brain Neoplasms↗
PubMed2005

O(6)-methylguanine DNA-methyltransferase (MGMT) overexpression in melanoma cells induces resistance to nitrosoureas and temozolomide but sensitizes to mitomycin C.

Alkylating agents play an important role in the chemotherapy of malignant melanomas. The activity of alkylating agents depends on their capacity to form alkyl adducts with DNA, in some cases causing cross-linking of DNA strands. However, the use of these agents is limited by cellular resistance induced by the DNA repair enzyme O(6)-methylguanine DNA-methyltransferase (MGMT) which removes alkyl groups from alkylated DNA strands. To determine to what extent the expression of MGMT in melanoma cells induces resistance to alkylating agents, the human cell line CAL77 Mer- (i.e., MGMT deficient) were transfected with pcMGMT vector containing human MGMT cDNA. Several clones expressing MGMT at a high level were selected to determine their sensitivity to chemotherapeutic drugs. Melanoma-transfected cells were found to be significantly less sensitive to nitrosoureas (carmustine, fotemustine, streptozotocin) and temozolomide with an increase of IC(50) values between 3 and 14 when compared to parent cells. No difference in cell survival rates between MGMT-proficient and -deficient cells was observed for melphalan, chlorambucil, busulphan, thiotepa and cisplatin which preferentially induce N(7) guanine lesions. Surprisingly, MGMT overexpression increased the sensitivity of CAL77 cells to mitomycin C by approximately 10-fold. Treatment of clonal cell lines with buthionine-[S,R]-sulfoximine (BSO), an inhibitor of gamma-glutamylcysteine synthetase which depletes cellular glutathione, completely reversed this unexpected increase in sensitivity to mitomycin C. This observation suggests that glutathione is involved in the sensitivity of MGMT-transfected cells to mitomycin C and may act synergistically with MGMT via an unknown mechanism.

Antineoplastic Agents↗
PubMed1991

Leptomeningeal dissemination of optic pathway gliomas in three children.

We treated three children with optic pathway gliomas who had progressive disease associated with metastatic spread to the leptomeninges. One patient had radiographic resolution of leptomeningeal disease after treatment with intravenous carmustine and oral mercaptopurine but died of progressive pulmonary fibrosis. The second patient was treated with intravenous thiotepa, and the leptomeningeal disease remained stable. The third patient was treated with intravenous vincristine sulfate, cyclophosphamide, cisplatin, and etoposide and had a significant size reduction of the leptomeningeal lesion. Although leptomeningeal dissemination is a seemingly rare event, it is important that all children with optic pathway gliomas be considered for this possibility, particularly after the onset of new, atypical neurologic symptoms.

Antineoplastic Agents↗
PubMed2000

On the significance of telomerase activity in human malignant glioma cells.

Telomerase is critical for tumor cell immortalization and is a novel target for cancer chemotherapy. Here, we examined whether telomerase is expressed in glioma cell lines, whether telomerase activity is regulated by bcl-2 or p53, and whether telomerase activity predicts response to chemotherapy. Further, we characterized the effects of a candidate telomerase inhibitor, penclomedine, in glioma cells. All 12 human malignant glioma cell lines examined were telomerase positive. Telomerase activity was not modulated during cell cycle progression, did not correlate with p53 status or bcl-2 family protein expression, and did not predict drug sensitivity, except for an association with resistance to carmustine. Ectopic bcl-2 expression did not enhance telomerase activity. Wild-type p53 reduced telomerase activity in cell lines retaining p53 activity but not in p53-mutant cell lines. Penclomedine killed glioma cells via an apoptotic, but death receptor-, bcl-2- and caspase-independent pathway, but did not inhibit telomerase and did not act synergistically with cytotoxic drugs. We conclude that telomerase activity does not account for the differential chemosensitivity of human glioma cells and that penclomedine kills glioma cells via a telomerase-independent pathway.

Animals↗