ly-355703 and Neoplasms

The cryptophycin analogue LY355703 is a potent inhibitor of microtubule polymerization that displays in vitro and in vivo activity in cell lines and tumor xenografts displaying the multidrug-resistant phenotype. In a Phase I trial, 25 patients received LY355703 as a 2-h i.v. infusion on day 1 and day 8 repeated every 3 weeks. Doses were escalated from 0.1 to 2.22 mg/m2 using a modified continual reassessment method. Neurological toxicity was found to be dose-limiting at 1.84 and 2.22 mg/m2. Among four patients treated at these doses, two had grade 4 constipation/ileus, one with severe myalgias, and one had grade 3 motor neuropathy. These findings were reversible. The 1.5 mg/m2 dose level was well tolerated. An amended twice-weekly schedule was pursued in 11 patients in an attempt to improve dose intensity and avoid dose-limiting neurotoxicity. Doses of >0.75 mg/m2 on a day 1, 4, 8, and 11 schedule every 21 days were not tolerated as a result of nausea/constipation, suggesting that LY335703 toxicity is not schedule dependent and is related to cumulative dose. LY355703 plasma concentrations measured by liquid chromatography with tandem mass spectrometry were evaluated using a population pharmacokinetic model. LY355703 was eliminated rapidly with a short terminal half-life that ranged from 0.8 to 3.9 h. Interpatient variability with respect to plasma clearance and volume of distribution, including covariates, was moderate at 32% and 39%, respectively. Maximum plasma concentration and area under the plasma concentration-time curve were linear over the dose range studied. A patient with non-small cell lung cancer previously treated with taxanes experienced a partial response lasting 4 months, and five patients had stable disease lasting > or =3 months. LY355703 at a dose of 1.5 mg/m2 is recommended for Phase II evaluation on a days 1 and 8 schedule. Twice-weekly dosing did not allow improvement in dose intensity or tolerability.

Topics: Adult; Aged; Aged, 80 and over; Antineoplastic Agents; Depsipeptides; Dose-Response Relationship, Drug; Female; Humans; Infusions, Intravenous; Lactams; Lactones; Male; Middle Aged; Models, Chemical; Models, Theoretical; Neoplasm Transplantation; Neoplasms; Peptides, Cyclic; Phenotype; Time Factors

LY355703 is a synthetic derivative of the marine cryptophycins, cytotoxic agents which induce mitotic arrest by binding at the microtubule vinca binding domain. Promising preclinical features of LY355703 were the 40-400 greater potency than paclitaxel or vinca alkaloids, the broad spectrum of antitumor activity in xenografts and the antitumour activity in multidrug resistant (MDR)-expressing murine tumours. Aims of this study were to define the maximum tolerated dose (MTD) and the dose recommended for Phase II, the pattern of toxicity, the pharmacokinetic profile and to document hints of antitumour activity of LY355703 given as 2-h infusion on day 1 every 3 weeks (Study 1) or, later on, on days 1, 8 and 15 every 4 weeks (Study 2). The latter weekly regimen was selected because of the acute dose-related toxicity reported in Study 1. The dose was escalated using a modified Continual Reassessment Method. Pharmacokinetic studies were performed on day 1 of cycle 1 in both studies; LY355703 plasma concentrations were assessed by liquid chromatography with tandem mass spectrometry. A total of 35 adult patients with solid tumours entered Study 1; the dose was escalated from 0.1 to 1.92 mg/m(2); at this dose 2 of 5 patients presented grade 3 neuropathy and myalgias; 1.48 mg/m(2) was then recommended for Phase II study. A total of 8 patients were treated in Study 2 at 1 mg/m(2); cumulative long-lasting neuroconstipation and neurosensory toxicity precluded the completion of the cycle in 9 out of 15 cycles; the clinical development of the weekly regimen was then discontinued. Other toxicities included cardiac dysrhythmia and mild alopecia. Pharmacokinetics of LY355703 appeared to be linear over the dose range studied. The administration of LY355703 on a 3-week schedule is associated with an acute dose-dependent peripheral neuropathy and myalgia of high interpatient variability for which possible risk factors and pharmacokinetic correlates could not be identified.

Topics: Adult; Aged; Antineoplastic Agents; Depsipeptides; Drug Administration Schedule; Female; Follow-Up Studies; Half-Life; Humans; Lactams; Lactones; Male; Maximum Tolerated Dose; Middle Aged; Neoplasms