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Biomedical subjects

C N Coleman

Publications and source records attributed to C N Coleman.

At least 73 records · Page 4Linked to original sources
PubMed1994

Use of the hypoxic cell sensitizer etanidazole (SR-2508) with intravenous melphalan and prednisone in the treatment of multiple myeloma: a pharmacokinetic study.

PURPOSE: A study was undertaken adding the alkylating agent sensitizer etanidazole to intravenous melphalan and oral prednisone for patients with multiple myeloma. This study explored the toxicity profile of these agents when given together and assessed the ability to attain adequate serum levels of etanidazole to permit sensitization to occur. METHODS AND MATERIALS: Etanidazole was administered intravenously in two doses of 3 g/m2 and 5 g/m2 90 min apart immediately prior to the administration of intravenous melphalan and oral prednisone for three consecutive cycles (total dose 24 g/m2). Patients received three additional cycles without etanidazole, allowing a comparison of hematologic toxicity from melphalan with and without etanidazole. RESULTS: Hematologic toxicity was moderate (Grade 3 or 4), but severity was similar during cycles with and without etanidazole. Only one patient developed a Grade 1 peripheral neuropathy questionably related to etanidazole. Most patients had etanidazole levels of > or = 70 ug/ml for 7 h, a level felt to be necessary for sensitization to occur. CONCLUSION: Etanidazole, administered as described, results in adequate serum levels for potential alkylating agent sensitization, without significant toxicity.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1994

Phase I pharmacokinetic study of the hypoxic cell sensitizer etanidazole with carboplatin and cyclophosphamide in the treatment of advanced ovarian cancer.

PURPOSE: A Phase I study was undertaken to determine the maximum tolerated dose of the hypoxic cell sensitizer etanidazole which could be administered with carboplatin and cyclophosphamide, to determine whether adequate serum levels of etanidazole were achieved to allow for alkylating agent sensitization, and whether pretreatment with etanidazole altered carboplatin pharmacokinetics. METHODS AND MATERIALS: Patients received 2 g/m2 of intravenous etanidazole followed by a second dose of 4 g/m2 90 min later, followed by intravenous carboplatin (300 mg/m2) and cyclophosphamide (600 mg/m2) for four treatment cycles. Patients received an additional two cycles of carboplatin and cyclophosphamide without etanidazole. RESULTS: Two patients who received a total of 24 g/m2 of etanidazole developed Grade 1 neurotoxicity, and therefore etanidazole doses were not escalated further. The grade of granulocytopenia was worse after cycles with etanidazole than after those without (p = 0.03), but clinical outcome was not different. Etanidazole levels were adequate for alkylating agent sensitization (> 70 ug/ml) in all patients for the majority of the 7 h of testing. Pharmacokinetic data suggested t1/2 alpha and t1/2 beta for carboplatin were prolonged after pretreatment with etanidazole. CONCLUSION: Etanidazole, 2 g/m2 followed by 4 g/m2 90 min later, is safe and results in adequate serum levels for alkylating agent sensitization. Neurotoxicity appears to prevent dose escalation of etanidazole, and an interaction between etanidazole and carboplatin may have enhanced neurotoxicity in these patients.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1994

Phase II trial of external beam radiation with etanidazole (SR 2508) for the treatment of locally advanced prostate cancer.

PURPOSE: To evaluate the efficacy and toxicity of the addition of etanidazole (ETA) to external beam radiation. METHODS AND MATERIALS: Fifty eight previously untreated patients with locally advanced adenocarcinoma of the prostate were entered on a Phase II trial of etanidazole (ETA) combined with standard external beam radiation therapy. ETA was given concurrently with irradiation. Four patients received less than 25% of the intended dose of ETA and were ineligible for further analysis. The stage of the remaining patients were T2c-11, T3-39, T4-1, bulky local recurrence after prostatectomy-1, and T3, N1-2. RESULTS: Forty-five of 54 patients (83.3%) achieved a clinical complete response (CCR) in the prostate and seminal vesicles as judged by digital rectal exam (DRE). Responses were rapid with a median time to CCR of 3.4 months, range 0-22.8 months. Local control was maintained in 82% of the patients who achieved a CCR. Fifteen of 32 eligible patients with a normal DRE underwent prostate biopsies from 12-20 months after treatment, seven had negative biopsies (46.6%). Distant metastases occurred in 18 patients (33.3%). Pretreatment prostatic specific antigen (PSA), Gleason score, and stage were not associated with treatment outcome in a univariate analysis. CONCLUSION: While ETA plus radiation was associated with a rapid CCR, the overall treatment outcome of these patients appeared to be similar to published reports of patients receiving RT alone. The rapid response rate may imply biologic activity of the ETA. In future trials, it may be reasonable to focus on patients at lower risk for the subsequent development of distant disease.

Adenocarcinoma↗
PubMed1994

A phase I study of etanidazole and radiotherapy in malignant glioma.

PURPOSE: To determine the maximum tolerable total dose (MTD) of etanidazole (ETA) when administered with external beam radiotherapy (XRT) and as a continuous infusion during stereotactic brachytherapy for patients with malignant glioma (anaplastic astrocytoma or glioblastoma multiforme or mixed cell tumors). METHODS AND MATERIALS: Seventy previously untreated patients were entered in a Phase I study. Prior to initiation of treatment, patients were stratified according to whether or not they were candidates for interstitial implantation. The implant patients (IMP, n = 17 pt) received accelerated fractionation XRT 20 Gy BID (6 h apart) to 40 Gy in 2 weeks with ETA 2 gm/m2 x 6 doses, a 2 week break and then interstitial implant to 50 Gy (4-7 days) with a continuous infusion of ETA over 90-96 h. The two sequentially conducted nonimplant arms started with accelerated fractionation XRT 2 Gy BID (6 h apart) to 40 Gy in 2 weeks with ETA 2 gm/m2 x 4-5 doses/week. NonIMP 1 arm (n = 38) received a 2-week break before standard fractionated boost XRT of 20 Gy/day for 2 weeks to a total dose of 60 Gy with ETA. NonIMP 2 arm (n = 14) did not have the 2-week break. All patients had plasma pharmacokinetic monitoring of ETA. RESULTS: The dose-limiting toxicity (DLT) in the IMP group was the cramping/arthralgia syndrome (4) and the cumulative MTD was 26 gm/m2. For both nonIMP 1 and 2 the DLTs were peripheral neuropathy and the cramping-arthralgia syndrome. The MTD for nonIMP 1 was 34 gm/m2 and nonIMP 2, 30 gm/m2. CONCLUSION: The clinical efficacy and radiation-related toxicity of these regimens are being evaluated. The doses of ETA that can be used with accelerated fractionation and with external beam irradiation plus brachytherapy have been established.

Adult↗
PubMed1994

Novel concepts in modification of radiation sensitivity.

PURPOSE: To determine whether biological effects of radiation, such as apoptosis, that differ from classical clonogenic cell killing, can be modified with agents that would not be expected to modify classical clonogenic cell killing. This would expand the range of potential modifiers of radiation therapy. METHODS AND MATERIALS: EL4 murine lymphoma cell apoptosis was determined by electrophoretic analysis of deoxyribonucleic acid (DNA) fragmentation. DNA was extracted 24 h after irradiation or addition of inducing agents. Modifiers of radiation-induced apoptosis were added immediately after irradiation. The effects of radiation on wounded endothelial monolayers were studied by scraping a line across the monolayer 30 min after irradiation. Cell detachment was used as an endpoint to determine the protective effect of prolonged exposure to retinol prior to irradiation. RESULTS: EL4 cell apoptosis can be induced by tert-butyl hydroperoxide or the glutathione oxidant SR-4077. Radiation-induced EL4 cell apoptosis can be inhibited with 3-aminobenzamide, an agent that sensitizes cells to classical clonogenic cell killing. Radiation-induced endothelial cell detachment from confluent monolayers can be modified by pretreatment with retinol. CONCLUSION: These results raise the possibility that radiation could induce apoptosis by an oxidative stress mechanism that is different from that involved in classical clonogenic cell killing. These and other recent findings encourage the notion that differential modification of classical clonogenic cell killing and other important endpoints of radiation action may be possible.

Animals↗
PubMed1994

Modification of the aerobic cytotoxicity of etanidazole.

PURPOSE: To determine the feasibility of modifying the aerobic cytotoxicity of etanidazole without interfering with the tumoricidal action of radiation plus etanidazole. METHODS AND MATERIALS: The aerobic cytotoxicity of etanidazole was studied using two different models: (1) Induction of apoptosis in EL4 cells: apoptotic DNA fragmentation was analyzed by agarose gel electrophoresis following 24 h treatment with etanidazole alone or in combination with various modifiers. (2) Spinal cord neuronal loss in organotypic roller tube cultures: Survival of acetylcholinesterase positive ventral horn neurons was analyzed morphometrically following 72 h treatment with etanidazole alone or in combination with vitamin E succinate. RESULTS: Etanidazole (10 mM) induced apoptosis in EL4 cells. This effect was suppressed by 24 h treatment with TPA, IBMX, the free radical scavenger TEMPOL or vitamin E succinate. Vitamin E succinate also protected spinal cord cultures from etanidazole-induced neuronal loss. CONCLUSION: These results suggest that it might be possible to modify the neurotoxicity of etanidazole with agents that would not be expected to interfere with the tumoricidal action of radiation plus etanidazole.

Aerobiosis↗
PubMed1994

Bioreductive metabolism of SR-4233 (WIN 59075) by whole cell suspensions under aerobic and hypoxic conditions: role of the pentose cycle and implications for the mechanism of cytotoxicity observed in air.

PURPOSE: Measurement of pentose cycle (PC) activity is shown to be a noninvasive means for monitoring the reduction of SR-4233 in whole cells. Comparing these measurements to the actual measurements of drug loss under aerobic and hypoxic conditions helps to define the mechanism for the associated aerobic toxicity. METHODS AND MATERIALS: SR-4233 is activated to a toxic species by bioreductive metabolism. NADPH is required for the activation of the drug by purified enzymes, cell homogenates and whole cells. In vivo the NADPH:NADP+ ratio is maintained by the oxidation of glucose via the oxidative limb of the pentose cycle. By measuring radiolabeled 14CO2 released as a product of this oxidation one can get an accurate measurement of the rate of drug metabolism in whole cells. These results are compared to measurements of drug consumption under aerobic and hypoxic conditions using an HPLC assay. RESULTS: SR-4233 stimulates pentose cycle activity to a greater extent in air then under hypoxia, however, in the presence of added catalase, pentose cycle activity is stimulated to a similar extent under both conditions. The higher levels of PC activity observed in air are due to the production of hydrogen peroxide by the nitroxide free radical undergoing futile redox cycling. The contribution of H2O2 to the observed aerobic cytotoxicity of SR-4233 is minimal however, since toxicity is only slightly reduced in the presence of exogenous catalase and antioxidants such as vitamin E. The level of PC stimulation by SR-4233 suggests that the rate of electron addition to the drug is independent of O2 concentration. The loss of drug from the incubation medium, i.e., conversion to a stable intermediate species, occurs approximately five times faster under nitrogen than in air for A549 cells. It is the rate of drug loss from the cell and not the rate of reduction which best correlates with the observed aerobic and hypoxic toxicity. CONCLUSION: Toxicity in air and in nitrogen is directly related to the rate of drug reduction, i.e., at equivalent levels of drug loss we observe equal levels of cytotoxicity.

Aerobiosis↗
PubMed1994

Muscle cramping in phase I clinical trials of tirapazamine (SR 4233) with and without radiation.

PURPOSE: Tirapazamine (SR 4233) is a benzotriazine di-N-oxide which acts as a hypoxic cytotoxic agent and as a radiation enhancer when given shortly before or after radiation. Three Phase I clinical trials were designed to determine the maximum tolerated dose, toxicities, pharmacokinetics, and effects on irradiated tumors and normal tissues. METHODS AND MATERIALS: Tirapazamine 9 mg/m2 to 21 mg/m2 was given i.v. 1/2 to 1 h prior to irradiation on a multiple dose schedule of 10 consecutive doses. This was later revised to a three times-per-week schedule for 12 doses. In a second clinical trial, tirapazamine was given in a single dose of 18 mg/m2 to 293 mg/m2 i.v. after irradiation. In a third trial, tirapazamine was administered without irradiation in single doses of 36 mg/m2 to 250 mg/m2, with an option for retreatment. RESULTS: Subjects reported muscle cramping of varying degrees of severity on all three dose schedules. One patient experienced Grade 3 cramping and treatment was discontinued. The most frequent site of cramping were the lower extremities. Creatine phosphokinase (CPK) values were elevated in three patients with associated muscle soreness in one patient. MB (cardiac) isoenzymes were elevated in one patient with no evidence of cardiac muscle damage, and returned to baseline at drug completion. No consistent abnormalities in clinical laboratory values were found. Stretching of the muscle was most effective in relieving the cramping. CONCLUSION: Muscle cramping has been the most frequently reported toxicity in Phase I studies of tirapazamine, though it does not appear to be dose limiting. Dose escalation on the three clinical trials continues. In vitro studies to investigate the cramping are ongoing.

Adult↗
PubMed1994

Pharmacodynamics of prolonged treatment with L,S-buthionine sulfoximine.

PURPOSE: To develop dosing criteria for the use of L-buthionine-S-sulfoximine (active diastereoisomer) as a glutathione depletor in the clinic, using a pharmacodynamic and pharmacokinetic in vitro-in vivo approach. METHODS AND MATERIALS: In vitro: L-buthionine-S-sulfoximine uptake was determined in human glioblastoma cells (T98G) and NIH-3T3 cells using 35S-labeled drug. Dose response relationships were derived for inhibition of glutathione synthesis in CHO cells, and for depletion of glutathione in exponentially growing T98G and CHO cells, as a function of extracellular L-buthionine-S-sulfoximine concentration. Steady-state glutathione levels for CHO and NIH-3T3 cells were measured using an enzymatic assay, while glutathione synthesis rates in CHO cells were determined using a flow cytometric assay. In vivo: L-buthionine-S-sulfoximine biodistribution was determined in male nude mice carrying human glioblastomas (T98G) intracranially, using 35S-labeled drug infused subcutaneously by osmotic pump. Tissue glutathione levels were measured using an enzymatic assay. RESULTS AND CONCLUSION: The observed cellular uptake t1/2 of approximately 55 min, coupled with a previously reported, rapid in vivo clearance of buthionine sulfoximine, suggest that continuous infusion would be preferable to bolus dosing. Effective concentrations of L-buthionine-S-sulfoximine (24 h exposure), required to lower cellular glutathione content to 50% of control (EC50), were under 1 mM for both cell lines. The amount of L-buthionine-S-sulfoximine in tissues (estimated from 35S drug disposition) reached steady state within 8 h and was proportional to the rate of infusion. Brain tumors were depleted to approximately 50% of control glutathione by a infusion rate of 0.25 mumoles/h (25 g mice). At lower infusion rates an increase in glutathione content was noted in certain nude mouse tissues including brain tumor xenografts.

3T3 Cells↗
PubMed1994

RTOG #89-06: a phase I study to evaluate intraoperative radiation therapy and the hypoxic cell sensitizer etanidazole in locally advanced malignancies.

PURPOSE: To identify the maximum tolerated dose of the oxygen mimetic radiation sensitizer Etanidazole in the setting of surgery and intraoperative radiation therapy. 12 grams/meter2 was the maximum chosen target dose based on tolerance from other trials. METHODS AND MATERIALS: 42 patients were entered in an escalating dose scheme, 5.5, 7.5, 9, 10.5, and 12.0 grams/meter2. Etanidazole was given via intravenous infusion over 15 minutes, followed within 20 to 30 minutes by intraoperative radiation therapy. Multiple tissue samples from tumor, tumor bed, and/or normal tissue were obtained with simultaneous plasma samples. Etanidazole concentrations in tissue and serum were determined in 33 of the 42 patients. RESULTS: The median time to maximum serum concentration was 25 minutes. Median time to maximum tissue concentration was 40 minutes. Tissue concentrations began falling approximately one hour after infusion. Acute drug toxicities were minimal. Toxicities reported during follow-up related to surgery and/or radiation, not to drug. The concentration of sensitizer in tumor/tumor bed tissues was ten-fold greater than in previous trials. A sensitizer enhancement ratio for the hypoxic cells of 2 to 2.5 is projected. CONCLUSION: On the basis of tissue biopsy information, intraoperative radiation therapy will be given 40 minutes after the start of the 15 minute infusion allowing time for maximum intracellular uptake into tumor cells. In view of these findings, a Phase III trial testing etanidazole with intraoperative radiation therapy will be conducted. The tolerable single dose level of 12 grams/meter2 has potential with other high-dose radiation settings such as brachytherapy or stereotactic radiosurgery.

Adolescent↗
PubMed1994

Rate of relapse following treatment for localized prostate cancer: a critical analysis of retrospective reports.

PURPOSE: Controversy exists over the optimal treatment for patients with clinically localized prostate cancer. Almost all of the treatment results are from non-randomized trials and interseries comparison is difficult since the apparent success of a treatment, as judged by the actuarial freedom from relapse and survival data, depends on patient selection criteria and post-treatment evaluation, in addition to the efficacy of the therapeutic intervention. In this report the calculation of a hazard function is used to estimate and compare the rate of relapse for the different treatments. METHODS AND MATERIALS: Clinical reports from major surgery and radiation oncology treatment institutions were analyzed. The actuarial recurrence data were used to calculate the annual rate of recurrence within each series. RESULTS: For all but the lowest volume tumors, patients continue to be at risk of relapse for as long as these series have been followed. Despite the heterogeneity of patient populations, the recurrence rates by stage are similar for patients treated with surgery or irradiation. This result is consistent with pathologic data from prostatectomy specimens which indicate that for lesions > 12 cm3 (approx. 3 cm in diameter) there is high likelihood of extraprostatic disease. CONCLUSION: Treatment outcome for patients with localized prostate cancer may be more dependent on the inherent tumor biology than the particular type of treatment. Accordingly, the expectation and recommendation of a treatment must take into consideration the continued risk of relapse with either radiation therapy or surgery. There are, as yet, insufficient data regarding the impact of screening and earlier diagnosis on the curability of patients with localized prostate cancer.

Humans↗
PubMed1994

X-irradiation, phorbol esters, and H2O2 stimulate mitogen-activated protein kinase activity in NIH-3T3 cells through the formation of reactive oxygen intermediates.

Extracellular signal-regulated kinases (ERKs), also known as mitogen-activated protein (MAP) kinases, are rapidly phosphorylated and activated in response to a number of external factors which promote growth and differentiation (T. G. Boulton, S. H. Nye, D. J. Robbins, N. Y. Ip, E. Radziejewska, S. D. Morgenbesser, R. A. DePinho, N. Panayotatos, M. H. Cobb, and G. D. Yancopoulos, Cell, 65: 663-675, 1991; S. L. Pelech and S. S. Jasbinder, Science (Washington DC), 257: 1355-1356, 1992; G. Thomas, Cell, 68: 3-6, 1992). We have identified two novel stimulators of MAP kinase activity, ionizing radiation and H2O2. Both radiation and H2O2, as well as the known agonist 12-O-tetradecanoylphorbol 13-acetate activate MAP kinase through the production of reactive oxygen intermediates. Our results demonstrate a direct link between the MAP kinase signal transduction pathway and reactive oxygen species and provide a unifying mechanism for activation of early- and late-response genes by inducers of oxidative stress.

3T3 Cells↗
PubMed1994

Radiation-induced apoptosis in F9 teratocarcinoma cells.

We have found that F9 murine teratocarcinoma cells undergo morphological changes and internucleosomal DNA fragmentation characteristic of apoptosis after exposure to ionizing radiation. We studied the time course, radiation dose-response, and the effects of protein and RNA synthesis inhibitors on this process. The response is dose dependent in the range 2-12 Gy. Internucleosomal DNA fragmentation can be detected as early as 6 h postirradiation and is maximal by 48 h. Cycloheximide, a protein synthesis inhibitor, and 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole, an RNA synthesis inhibitor, both induced internucleosomal DNA fragmentation in the unirradiated cells and enhanced radiation-induced DNA fragmentation. F9 cells can be induced to differentiate into cells resembling endoderm with retinoic acid. After irradiation, differentiated F9 cells exhibit less DNA fragmentation than stem cells. This indicates that ionizing radiation can induce apoptosis in non-lymphoid tumours. We suggest that embryonic tumour cells may be particularly susceptible to agents that induce apoptosis.

Animals↗
PubMed1994

Improved survival in patients with limited stage IIIA Hodgkin's disease treated with combined radiation therapy and chemotherapy.

PURPOSE: Patients with laparotomy-staged (PS) III 1A Hodgkin's disease confined to the upper abdomen are believed to have a favorable prognosis and require less aggressive treatment than patients with more-extensive stage III disease. We evaluated prognostic factors and outcome in 93 patients with PS III 1A Hodgkin's disease treated either with radiation therapy (RT) alone or combined RT and chemotherapy (combined modality treatment [CMT]) to determine the extent of treatment needed in this subgroup of stage IIIA patients. MATERIALS AND METHODS: We retrospectively reviewed the freedom from relapse (FFR) rate, sites of recurrence, and survival rate of PS III 1A patients selected to receive extended-field irradiation (MPA, n = 27), total-nodal irradiation (TNI, n = 34), and CMT (n = 32) between 1969 and 1987. CMT consisted of six cycles of mechlorethamine, vincristine, procarbazine, and prednisone (MOPP) chemotherapy and MPA. Patients treated with MPA were part of a prospective trial designed to reduce treatment to patients with minimal stage III disease with very favorable characteristics. RESULTS: Histologic subclass and treatment were the only prognostic factors for FFR and survival rates. Patients with nodular sclerosis or lymphocyte predominance histology had significantly higher FFR and survival rates compared to patients with mixed-cellularity (MC) histology. The 10-year actuarial FFR of PSIII 1A patients treated with MPA was only 39%, versus 55% for TNI (P = .02) and 94% for CMT (v MPA, P < .0001; v TNI, P = .006). The patterns of recurrence in patients who received MPA and TNI were significantly different, with MPA patients relapsing more often in untreated pelvic or inguinal nodes, and TNI patients relapsing more often in extranodal sites with or without nodal sites. The 10-year actuarial overall survival rate for patients treated with CMT was 89% versus 78% for MPA (v CMT, P = .09) and 70% for TNI (v CMT, P = .05). CONCLUSION: Patients with PSIII 1A Hodgkin's disease treated with RT have a significantly higher risk of relapse and potentially a poorer survival compared with patients treated with CMT. These findings suggest that CMT should play a greater role in the treatment of this favorable substage of patients. Management with modified chemotherapy and RT in an attempt to reduce long-term treatment-induced complications may be a preferred approach for future trials.

Adolescent↗