Showing papers by "Ross C. Donehower published in 1991"

Cardiac disturbances during the administration of taxol.

Abstract: 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.

Phase I and Pharmacokinetic Study of Hepsulfam (NSC 329680)

Abstract: Hepsulfam (NSC 329680), a bifunctional alkylating agent structurally related to busulfan, has entered clinical trial based on its broader preclinical antitumor activity compared with that of busulfan and its i.v. formulation which may circumvent the many problems arising from the p.o. administration of busulfan, such as significant individual differences in bioavailability. In this Phase I study, 53 patients received 95 courses of hepsulfam at doses ranging from 30 to 480 mg/m2 administered i.v. over 30 min every 28 days. Hematological toxicity was dose limiting. Leukopenia and thrombocytopenia were dose related, delayed in onset, and sustained for long durations. Toxicity was cumulative in most patients receiving more than one course. This pattern of myelosuppression suggests that hepsulfam is cytotoxic to hematopoietic stem cells. Although hematological toxicity was not particularly severe during most courses, its lengthly duration precluded the prompt administration of subsequent courses. Minimal nonhematological effects were observed. Pharmacokinetic studies revealed that the clearance rate of hepsulfam is linear over the dose range studied and that its plasma disposition is biphasic with mean alpha and beta half-lives of 19 +/- 18 (SE) min and 337 +/- 248 (SE) min, respectively. The area under the plasma clearance curve correlated with the percentage of change in WBC using a sigmoidal Emax model and with the duration of thrombocytopenia in patients with hematological toxicity. Based on the protracted duration of the toxicity of multiple doses that were greater than 210 mg/m2, the recommended starting dose for Phase II trials is 210 mg/m2. However, these trials should be pursued with caution because of the protracted nature of hepsulfam's myelosuppression. Because hepsulfam produced minimal nonhematological toxicity, substantial dose escalation above 480 mg/m2 may be possible with hematopoietic stem cell support.

Pharmacologic, Pre-clinical and Clinical Investigations of the Cisplatin/Taxol Combination

Abstract: Taxol, the prototype of a novel class of antimicrotubule agents that is derived from the bark of the Pacific yew Taxus brevifolia, induces excessive polymerization of tubulin and impairs the dynamic equilibrium between tubulin and microtubules interfering with normal cellular functions.1–4 Taxol (Figure 1) is the first compound with a taxene ring that has been demonstrated to possess antineoplastic activity,5 and it has become one of the most important lead anticancer agents to recently emerge from the screening of natural products.