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Biomedical subjects

R C Donehower

Publications and source records attributed to R C Donehower.

At least 91 records · Page 5Linked to original sources
PubMed1991

Solitary, isolated metastasis from Ewing's sarcoma to the brain: case report.

We report a case of a 30-year-old woman who developed an intraparenchymal cerebral metastasis from a Ewing's sarcoma of the chest wall diagnosed and treated 3 years earlier and in apparent remission at the time of the neurological presentation (seizures). The case was complicated by a spontaneous preoperative intratumoral hemorrhage that occurred the morning of the scheduled surgical resection and caused a left dense hemiparesis. The tumor and the hematoma were removed. The patient improved after surgical intervention and a postoperative course of cranial irradiation followed by systemic chemotherapy was given. Nineteen months after treatment the patient remains disease-free from the clinical and radiological standpoint.

Adult↗
PubMed1991

The clinical pharmacology and use of antimicrotubule agents in cancer chemotherapeutics.

Although there has been a rapid expansion of the number of classes of compounds with antineoplastic activity, few have played a more vital role in the curative and palliative treatment of cancers than the antimicrotubule agents. Although the vinca alkaloids have been the only subclass of antimicrotubule agents that have had broad experimental and clinical applications in oncologic therapeutics over the last several decades, the taxanes, led by the prototypic agent taxol, are emerging as another very active class of antimicrotubule agents. After briefly reviewing the mechanisms of antineoplastic action and resistance, this article comprehensively reviews the clinical pharmacology, therapeutic applications, and clinical toxicities of selected antimicrotubule agents.

Alkaloids↗
PubMed1991

Cardiac disturbances during the administration of taxol.

The clinical development of taxol, a new antimicrotubule agent with a unique mechanism of cytotoxic action, has proceeded slowly due to serious hypersensitivity reactions (HSRs) and shortages in its supply. Nevertheless, large-scale phase II trials have been initiated as taxol has recently demonstrated impressive activity in advanced and cisplatin-refractory ovarian carcinoma. Furthermore, the incidence of HSRs has been reduced substantially with premedications and modifications in the administration schedule. However, various manifestations of potential cardiotoxicity have been observed in several patients who participated in four phase I and II studies of taxol. Asymptomatic bradycardia has occurred in a high proportion of patients, including 29% of ovarian cancer patients who were treated with maximally tolerated doses of taxol in a phase II study. More profound cardiac disturbances, including a range of atrioventricular conduction blocks, left bundle branch block, ventricular tachycardia (VT), and manifestations of cardiac ischemia, have been observed in seven of 140 patients (5%) who received taxol. Descriptions of these events are presented in this report to alert investigators to the potential for these adverse effects. Although these disturbances did not result in serious sequelae in most patients, investigators should continue to maintain a high degree of caution until precise risk factors, frequency, and clinical significance of these adverse cardiac effects are determined.

Aged↗
PubMed1990

Effects of the differentiating agent hexamethylene bisacetamide on normal and myelodysplastic hematopoietic progenitors.

Hexamethylene bisacetamide (HMBA; NSC 95580) is a potent polar-planar differentiating agent of leukemia and solid tumor cell lines in vitro at clinically achievable concentrations. HMBA is currently being studied in patients with myelodysplastic syndrome. Previous phase I trials have demonstrated that HMBA produces hematologic toxicity in morphologically normal bone marrows of patients with solid tumors. Because of concern that HMBA may produce more severe myelotoxicity in patients with myelodysplastic syndrome since these patients have limited hematopoietic reserves, we studied the effects of HMBA on myelodysplastic and normal hematopoietic progenitors in vitro. HMBA concentrations that are optimal for differentiation in vitro (2 to 5 mmol/L) and HMBA concentrations that are being achieved in clinical trials (1 to 2 mmol/L) inhibited the growth of granulocyte-macrophage colony-forming units and erythroid burst-forming units from all 15 patients with myelodysplastic syndrome and all 4 normal subjects, HMBA did not induce proliferation of myelodysplastic or normal progenitors at any concentration; rather, it produced nearly identical inhibition of normal and myelodysplastic hematopoietic progenitors. HMBA also produced quantitatively similar inhibition of clonogenic leukemic growth of two myeloid leukemia cell lines. For a differentiating agent to be effective, it will likely have to either produce both differentiation and proliferation of abnormal hematopoietic progenitors or show selective inhibitory effects on abnormal as compared with normal progenitors. Although the mechanisms responsible for the antiproliferative effects of HMBA cannot be determined from this study, similar inhibitory effects of HMBA on normal and abnormal hematopoietic progenitors suggest that HMBA may be of limited utility in producing and sustaining elevations of peripheral blood cell counts in patients with myelodysplastic syndrome.

Acetamides↗
PubMed1990

Taxol: a novel investigational antimicrotubule agent.

Microtubules are among the most strategic subcellular targets of anticancer chemotherapeutics. Despite this fact, new antimicrotubule agents that possess unique mechanisms of cytotoxic action and have broader antineoplastic spectra than the vinca alkaloids have not been introduced over the last several decades--until the recent development of taxol. Unlike classical antimicrotubule agents like colchicine and the vinca alkaloids, which induce depolymerization of microtubules, taxol induces tubulin polymerization and forms extremely stable and nonfunctional microtubules. Taxol has demonstrated broad activity in preclinical screening studies, and antineoplastic activity has been observed in several classically refractory tumors. These tumors include cisplatin-resistant ovarian carcinoma in phase II trials and malignant melanoma and non-small cell lung carcinoma in phase I studies. Taxol's structural complexity has hampered the development of feasible processes for synthesis, and its extreme scarcity has limited the use of a conventional, broad-scale screening approach for evaluation of clinical antitumor activity. However, taxol's unique mechanism of action, its spectrum of preclinical antitumor activity, and tumor responses in early clinical trials have generated renewed interest in pursuing its development.

Alkaloids↗
PubMed1990

Phase I study and pharmacodynamics of piroxantrone (NSC 349174), a new anthrapyrazole.

Piroxantrone (PRX, NSC 349174) is one of the first of a new class of intercalating agents, the anthrapyrazoles, to undergo clinical evaluation. Additionally, it is the first drug trial to prospectively test a new pharmacology-based dose escalation schema proposed for Phase I trials of anticancer compounds. In this Phase I trial, PRX was administered as a 1-h infusion every 3 weeks to patients with advanced cancer. Forty-four evaluable patients received 116 courses at doses ranging from 7.5 to 190 mg/m2. The dose-limiting toxicity was myelosuppression with leukopenia predominating. Nonhematological toxicities were minimal and consisted of nausea and vomiting, alopecia, mucositis, and phlebitis. Based on this trial, the maximum tolerated and recommended Phase II doses for PRX administered on this schedule are 190 and 150 mg/m2, respectively. PRX plasma elimination was rapid and best fit by a two-compartment model for 17 of 24 patients receiving greater than or equal to 90 mg/m2. The plasma clearance rate was 1290 +/- 484 ml/min (720 +/- 210 ml/min/m2) and did not vary with dose. The t1/2 alpha was 2.9 +/- 5.3 (SD) min and the t1/2 beta was 18.7 +/- 36.5 min. Area under the concentration versus time curve (AUC) at the maximal tolerated dose (MTD) was 435 mumol.min/liter, 40% higher than the predicted AUC from preclinical testing. The percentage decrease in WBC and neutrophil count was correlated with the AUC. The potential advantage of pharmacology-based dose escalation was limited in this study by assay insensitivity, extremely rapid plasma elimination, and the proximity of the starting dose to the dose where the target AUC was achieved and standard dose escalations were to begin. Consequently, there was no reduction in the number of dose escalations required to define the maximum tolerated dose. However, the practical aspects of this approach have been established and its use is recommended for further trials where detailed preclinical pharmacological studies are available.

Adult↗
PubMed1990

Sixteen-week dose-intense chemotherapy in the adjuvant treatment of breast cancer.

Fifty-three women with breast cancer were treated with a new 16-week dose-intense, chemotherapy regimen. Patients with operable breast cancer with 10 or more histologically positive axillary nodes were treated with this five-drug regimen that incorporated the concepts of weekly chemotherapy, sequential administration of antimetabolites, and continuous infusion of fluorouracil (5-FU). The chemotherapy regimen consisted of eight cycles (each of 2 wk duration) of 100 mg of cyclophosphamide/m2 orally on days 1-7, 40 mg of doxorubicin/m2 intravenous (IV) on day 1, 100 mg of methotrexate/m2 IV on day 1 with 10 mg of leucovorin rescue/m2 every 6 hours for six oral doses on day 2, 1 mg of vincristine IV on day 1, and 600 mg of 5-FU/m2 IV at hour 20 over 2 hours. A continuous infusion of 300 mg of 5-FU/m2 per day was given IV on days 8-9 of each 2-week cycle. The doses and schedule of drug administration were designed to minimize dosage reduction and treatment delay. At a median follow-up of 17 months, there have been eight relapses in the 53 patients. The actuarial 3-year disease-free survival is 80% (95% confidence interval, 62% to 90%). The major side effects were attributable to myelosuppression. Absolute neutrophil counts less than 250/microL were noted in 12 (23%) patients; seven patients (13%) required hospitalization for management of neutropenic fever. No treatment-related deaths occurred. Ninety-four percent of the planned doses were administered, and only 5% of the courses were delayed because of toxic reactions. The encouraging therapeutic data, manageable side effects, and our ability to deliver over 90% of the planned doses provide the rationale for a phase III comparison of this new dose-intense regimen and standard chemotherapy in patients with operable disease and positive axillary nodes.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1990

Development of polyploidization in taxol-resistant human leukemia cells in vitro.

The effects of taxol on antitubulin immunofluorescent staining patterns, cellular DNA content, and labeling with [3H]thymidine were measured for the taxol-sensitive HL60 and taxol-resistant K562 cell lines after exposures for 0, 4, 12, and 24 h. Taxol caused a relative increase in the fraction of 4C interphase and metaphase cells in both lines although the 4C interphase accumulation was greater for the resistant K562 line. Of the cells with S-phase DNA content, taxol-treated HL60 cells were less likely to incorporate [3H]thymidine than taxol-treated K562 cells. However, a decrease in percentage of S-phase labeling for both lines relative to control cells was seen. Finally, taxol induced the development of polyploid cells (cells with DNA contents greater than that of the 4C G2-M peak) in the relatively taxol-resistant K562 cells, an effect not seen in the relatively taxol-sensitive HL60 line. After 24 h of taxol exposure 70% of all K562 cells were polyploid while only 8% of the HL60 cells were polyploid. The capacity of K562 cells to generate polyploidy in response to taxol correlated with taxol resistance by previous assay and may be a useful indicator of drug resistance.

Alkaloids↗
PubMed1990

Phase II trial of menogaril as initial chemotherapy for metastatic breast cancer.

Eighteen women with metastatic breast cancer previously untreated with chemotherapy were entered on a phase II trial of intravenous menogaril, a new anthracycline derivative. Treatment was given at 140 mg/m2 on days 1 and 8 of each 28 day cycle. The most common toxicities were leukopenia in all patients and burning and phlebitis at infusion sites in 72%. Serial assessment of cardiac function by resting and stress gated blood pool scans showed temporary decrements in ejection fraction in only 2 patients (11%). The response rate to the therapy was 19% [95% CI 0-38%] including 1 complete and 2 partial responses. The median time to relapse among responders was 6.5 months. Mean survival in all patients entered was 15.8 months from date of entry. Menogaril at this dose and schedule has modest activity as first line therapy for metastatic breast cancer but also has significant marrow and local toxicity.

Adult↗
PubMed1990

Hypersensitivity reactions from taxol.

Taxol is an antitumor agent in clinical trial that has been shown to have activity against advanced ovarian carcinoma and melanoma. Hypersensitivity reactions (HSRs) have been one of the toxicities observed with administration of this drug. Of 301 patients treated, 32 patients have had definite (27 patients) or possible (five patients) hypersensitivity reactions to taxol. All but one patient had the reaction from the first or second exposure to this agent. Reactions occurred at a variety of doses and were characterized most frequently by dyspnea, hypotension, bronchospasm, urticaria, and erythematous rashes. Thirteen (41%) patients had received premedication designed to prevent such toxicity; nevertheless, they sustained HSRs. Prolonging the drug infusion appears to have somewhat reduced, but not obviated, the risk of HSRs. The cause (taxol itself or its excipient Cremophor EL; Badische Anilin und Soda-Fabrik AG [BASF], Ludwigshafen, Federal Republic of Germany) and the mechanism of these reactions to taxol are unknown. We provide guidelines to prevent or minimize such toxicity and treat reactions if they still occur.

Adult↗
PubMed1990

Effects of rhGM-CSF on intracellular ara-C pharmacology in vitro in acute myelocytic leukemia: comparability with drug-induced humoral stimulatory activity.

Human acute myelocytic leukemia (AML) marrow cells respond to stimulation with increased proliferation and enhanced intracellular metabolism of the cytotoxic antimetabolite 1-B-D arabinofuranosylcytosine (ara-C). Our previous studies have focused on the drug-induced humoral stimulatory activity (HSA) present in serum following initial cytoreduction which augments in vitro growth and biochemical pharmacology. The activity of HSA likely relates to the presence of multiple stimulators. The effect of 18-hr culture in purified recombinant human granulocyte-macrophage colony stimulating factor (rhGM-CSF) (1 ng/ml) on in vitro AML marrow cell [3H]dThd incorporation into DNA, intracellular ara-C activation to the triphosphate form (ara-CTP), and subsequent ara-CTP retention were determined in leukemic cells of 11 patients and compared with cells similarly cultured in HSA-containing sera. The stimulatory effects of rhGM-CSF and HSA on both growth and pharmacologic parameters were comparable for each AML population, with maximal response to both regulators detected for FAB M2. These data demonstrate that GM-CSF acts similarly to HSA as an active stimulator of leukemic cell proliferation and net intracellular ara-C metabolism in vitro, and support clinical trials designed to examine the role of rhGM-CSF in enhancing ara-C cytotoxicity by increasing the growth fraction of drug-responsive target cells in vivo.

Adult↗
PubMed1989

Taxol: a unique antineoplastic agent with significant activity in advanced ovarian epithelial neoplasms.

STUDY OBJECTIVE: To assess the activity of taxol in patients with advanced, progressive, and drug-refractory ovarian cancer and to delineate more clearly the toxicity of taxol in this patient population. DESIGN: Nonrandomized, prospective phase II trial. PATIENTS: Forty-seven patients with drug-refractory epithelial ovarian cancer who had one or more lesions measurable in perpendicular diameters. Of these patients, 45 were evaluable for toxicity and 40 were evaluable for response. INTERVENTIONS: PATIENTS were treated every 22 days with varying doses of taxol (110 to 250 mg/m2 body surface) given as a 24-hour infusion with subsequent doses based on adverse effects. A premedication regimen was used to avoid acute hypersensitivity reactions. MEASUREMENTS AND MAIN RESULTS: Twelve patients (30%; CI, 16% to 44%) responded to taxol for periods lasting from 3 to 15 months. The dose-limiting toxicity was myelosuppression with leukocytes affected more severely and commonly than thrombocytes or reticulocytes. Leukopenia was usually brief in duration but was associated with sepsis in 3 cases (2 fatal). Other adverse effects included myalgias, arthralgias, alopecia, diarrhea, nausea, vomiting, mucositis, and peripheral neuropathy. Rare cases of cardiac and central neurotoxicity were also noted. CONCLUSIONS: Taxol is an active agent in drug-refractory ovarian cancer and deserves further study in combination with other active drugs in previously untreated patients with advanced ovarian cancer.

Alkaloids↗
PubMed1989

Phase I and pharmacodynamic study of taxol in refractory acute leukemias.

Taxol, a novel antimicrotubule agent that enhances tubulin polymerization and microtubule stability, was administered to adults with refractory leukemias as a 24-h i.v. infusion in a Phase I study. The primary objectives were to determine the maximum tolerated dose of taxol administered on this schedule to patients with acute leukemias and describe the nonhematological toxicities which became dose limiting. The starting dose, 200 mg/m2, was based on the maximum tolerated dose in solid tumor trials, in which myelosuppression precluded dose escalation. Seventeen patients received 28 evaluable courses at 200, 250, 315, and 390 mg/m2. Severe mucositis limited further dose escalation. Other nonhematological effects included peripheral neuropathy, alopecia, myalgias, arthralgias, nausea, vomiting, diarrhea, and an acute pulmonary reaction that was presumptively due to taxol's Cremophor vehicle. Mean peak taxol plasma concentrations at all dose levels were in the range of concentrations that were previously demonstrated to induce microtubule bundles, a morphological effect associated with cytotoxicity, in leukemia cells in vitro. Pretreatment blasts from 12 patients were incubated with taxol ex vivo. Taxol-induced microtubule bundles were apparent in the blasts of eight patients who also had cytoreduction of tumor, and sensitivity to bundle formation was related to the magnitude of antitumor activity. In contrast, taxol did not induce microtubule bundles ex vivo in the blasts of the other four total nonresponders. Based on this study, the maximum tolerated doses and recommended Phase II doses for taxol, limited by nonhematological toxicity and administered as a 24-h i.v. infusion to patients with refractory leukemias, are 390 and 315 mg/m2. Phase II trials at these myelosuppressive doses are required to determine taxol's activity in the treatment of leukemias. In addition, further evaluation of microtubule bundle formation ex vivo in Phase II studies is necessary to determine the ultimate utility of this assay in assessing tumor sensitivity to taxol.

Acute Disease↗
PubMed1989

Taxol toxicity. Epithelial necrosis in the gastrointestinal tract associated with polymerized microtubule accumulation and mitotic arrest.

Taxol, an antineoplastic agent with a novel mechanism of action, is currently undergoing Phase I trials at The Johns Hopkins Hospital, Baltimore. The authors recently observed striking mitotic arrest associated with epithelial necrosis and ulceration in an esophageal biopsy specimen. The biopsy specimen was taken from a patient who received taxol the day before endoscopy. Review of our autopsy files revealed four other cases in which taxol had been administered. Sections of esophagus, stomach, small intestine, colon, liver, skin, bone marrow, and testes were examined for evidence of mitotic arrest. Mitotic arrest was seen in the two patients who underwent autopsy who received taxol less than 11 days before death, whereas the two autopsy patients who received taxol more than 2 weeks before death did not show these changes. Although mitotic arrest was most prominent in the esophagus, it was also found in the stomach, small intestine, colon, liver, and bone marrow. The mitotic arrest was associated with bundling of intermediate filaments and appeared to be secondary to accumulation of polymerized microtubules. These results suggest that taxol induces a transient mitotic arrest associated with cell necrosis.

Adult↗
PubMed1989

Phase I trial of trimetrexate glucuronate on a five-day bolus schedule: clinical pharmacology and pharmacodynamics.

Trimetrexate glucuronate (TMTX), a nonclassical folate antagonist, has been evaluated clinically on several schedules. We have studied TMTX administered as an iv bolus for 5 consecutive days every 3 weeks in 35 patients with advanced solid tumors. Drug was given at doses ranging from 7.6 to 18.8 mg/m2. The maximal tolerated dose was 13.1 mg/m2 per day x 5 for patients without prior myelotoxic treatment and 7.6 mg/m2 per day x 5 for previously treated patients. Because of wide individual differences in drug tolerance, dose escalation in 25% increments is recommended for patients not experiencing toxic effects. The dose-limiting toxicity was neutropenia. Rash and mucositis were also significant. TMTX concentrations were measured 1 and 24 hours after each dose, and the data were fit by use of a one-compartment pharmacokinetic model. With this simplified sampling and modeling scheme, the mean total body clearance (+/- SD) of trimetrexate was 31 +/- 20 mL/min per m2 and the volume of distribution was 13 +/- 7 L/m2. Mean plasma concentrations 1 hour after a dose were 1.12, 2.43, 3.33, and 3.25 mumol/L at 7.6, 9.1, 10.9, and 13.1 mg/m2, respectively. The mean TMTX concentration (+/- SD) 24 hours after a dose was 114 +/- 87 nmol/L. The mean area under the concentration-versus-time curve at 13.1 mg/m2 was 2,266 mumol.min/L. The drug concentration 1 hour after the first dose and the area under the concentration-versus-time curve were highly correlated with leukopenia and thrombocytopenia (r = .6 and .65 and P = .0007 and .0001, respectively). The maximal tolerated dose on the daily x 5 schedule was 30% of the dose tolerated on an iv bolus schedule. The choice of drug schedule for clinical trials when murine and human pharmacokinetics differ is discussed. Phase II trials are under way with both the iv bolus and the daily x 5 schedules.

Adult↗
PubMed1989

Phase II study of N-methylformamide, spirogermanium, and 4-demethoxydaunorubicin in the treatment of non-small cell lung cancer (EST 3583): an Eastern Cooperative Oncology Group study.

One hundred forty-four patients with non-small cell lung cancer, the majority (72%) of whom had received previous chemotherapy, were evaluable in this randomized phase II study of N-methylformamide (N-MF), spirogermanium, and 4-demethoxydaunorubicin. There were two partial responses, one each with spirogermanium and 4-demethoxydaunorubicin. There were eight life-threatening complications (mostly hematologic) and two lethal complications (N-MF, hematologic; 4-demethoxydaunorubicin, gastrointestinal). The overall survival ranged from 9 days to 533 days with a median of 17.6 weeks. The following factors were associated with poor survival: Poor initial performance status, prior weight loss, presence of liver or subcutaneous metastases.

Aged↗
PubMed1989

Assessment of N-methylformamide (NMF) administered orally on a three times weekly schedule: a phase I study.

This phase I study was conducted to reevaluate the dose-limiting toxicities, maximum tolerated (MTD) and recommended phase II doses of oral NMF administered on a three times weekly schedule for 4 out of every 6 weeks. This schedule was based on the observation that prolonged administration of NMF was associated with the most efficacious antitumor activity in preclinical studies. Phase II trials that employed a starting dose of 800 mg/m2, determined in a previous phase I trial, were suspended because of frequent and severe toxicities. In the current study, a symptom complex characterized by nausea, vomiting, and malaise was the dose-limiting toxicity of oral NMF administered on this schedule. Other toxicities included hepatic enzyme elevations, mild myelosuppression, and worsening of preexistent toxic peripheral neuropathies. Of interest, three patients who were asymptomatic prior to treatment, rapidly developed symptoms of increased intracranial pressure after starting NMF; and, computerized tomographic brain scans revealed metastatic tumors with significant peritumoral edema. NMF was well tolerated at 600 mg/m2, however, an abrupt increase in toxicity resulted when the dose was increased to 700 mg/m2. Although NMF peak plasma concentrations (Cmax) and areas under the plasma disappearance curves (AUC) differed between the 600 and 700 mg/m2 dose levels, these differences were not striking, and similar NMF plasma concentrations and exposures were well tolerated during intravenous trials. Based on this study, the recommended phase II dose for oral NMF administered three times weekly for 4 of 6 weeks was 600 mg/m2.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗