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Aim: To determine the safe dose range and pharmacokinetics of metronomic oral vinorelbine and obtain preliminary data on biomarkers and efficacy in patients with advanced cancer. Methods: Successive cohorts of patients received escalated doses of oral vinorelbine given thrice a week until disease progression, unacceptable toxicity (UT), or consent withdrawal. UT was any grade 4 toxicity, or grade 2 or 3 toxicity that would result to longer than 2-week break during the first 2 months of treatment. Blood samples were collected for pharmacokinetics and quantification of angiogenesis regulatory proteins. Results: Sixty-two patients (median age, 60 years) enrolled at six dose levels from 20 to 70 mg and received treatment for median 12.25 weeks (range, 2-216+). Unacceptable toxicity occurred in two of six patients treated at 60 mg (leucopenia grade 4 and epistaxis grade 2) and in one at 70 mg (leucopenia grade 2). The upper metronomic dose was 50 mg. Objective antitumor response documented in eight cases and 32% of patients experienced disease stability for minimum 6 months. Three responders (renal cancer, medullary thyroid carcinoma, and Kaposi sarcoma) received nonstop treatment for over 3 years without overt toxicity. Low pretreatment levels of circulating interleukin-8, vascular endothelial growth factor, and basic fibroblast growth factor were found predictors of efficacy. Steady-state concentrations of vinorelbine and its active metabolite ranged from 0.5 to 1.5 ng/mL. Conclusions: Metronomic administration of oral vinorelbine is feasible at doses up to 50 mg thrice a week and can yield sustainable antitumor activity without overt toxicity, probably through antiangiogenic mechanism. Further clinical investigation is warranted. (Clin Cancer Res 2009;15(20):6454–61)

The availability of chemotherapeutic drugs administrable by oral route represents a step forward in the management of cancer patients. Among oral agents, vinorelbine is particularly interesting for its pharmacological characteristics and clinical efficacy. Oral vinorelbine is rapidly absorbed (1.5-3 hours) with an elimination half-life of approximately 40 hours. It shows a low level of binding to plasma proteins (13%), is highly bound to platelets (78%) and has a hepatic metabolism and an absolute bioavailability of 40% with a moderate and similar interpatient variability for the two forms. Food has no influence on the pharmacokinetic profile of oral vinorelbine even if nausea/vomiting is less frequent and less severe in the fed patients than in the fasting patients. Therefore, to ensure patient comfort, it is recommended that oral vinorelbine is administered with a snack. All the metabolites of oral vinorelbine have been identified and, among these, only deacetyl-vinorelbine presented activity demonstrating that for both oral and intravenous (i.v.) routes of administration the drug has the same metabolism pattern. Oral vinorelbine is eliminated mainly in a unconjugated form via the bile. In this process, the CYP 3A4 isoform of cytochrome P450 is mostly involved. Absorption of oral vinorelbine is not delayed in elderly patients. After oral administration, blood concentrations of vinorelbine in elderly patients are within the range of values observed in younger patients. The absolute bioavailability is close to 38% in elderly whereas it is close to 40% in younger patients. This difference is not significant. As compared to the intravenous drug, oral vinorelbine demonstrated linear pharmacokinetics as well an absolute bioavailability of approximately 40%, and a reliable dose-correspondence of 80 mg/m2 oral form --> 30 mg/m2 i.v. and 60 mg/m2 oral --> 25 mg/m2 i.v. Therefore, i.v. and oral forms show similar interindividual variability, same metabolism pattern, reproducible intra-patient blood exposure, and same pharmacokinetic-pharmacodynamic relationship. Oral vinorelbine has shown significant activity in advanced non-small cell lung cancer. Given at 60 mg/m2/week for the first 3 administrations and then increased to 80 mg/m2/week achieved the same efficacy as i.v. vinorelbine in terms of progression-free survival, overall survival, objective response. Mild-to-moderate gastrointestinal toxicity, easily manageable with standard treatment was recorded. Reproducible efficacy compared to previously reported results with vinorelbine i.v. Also, in advanced breast cancer, oral vinorelbine has shown significant activity with a good therapeutic index. Albeit no formal comparison between the oral and the intravenous formulations of vinorelbine has been made, however, the oral route seems to offer major advantages to patients who are faced with a clear decrease in the frequency of hospital admissions as compared to that needed to give intravenous chemotherapy.