Pharmacokinetic and pharmacogenetic determinants of the activity and toxicity of irinotecan in metastatic colorectal cancer patients.

This study aims at establishing relationships between genetic and non-genetic factors of variation of the pharmacokinetics of irinotecan and its metabolites; and also at establishing relationships between the pharmacokinetic or metabolic parameters and the efficacy and toxicity of irinotecan. We included 49 patients treated for metastatic colorectal cancer with a combination of 5-fluorouracil and irinotecan; a polymorphism in the UGT1A1 gene (TA repeat in the TATA box) and one in the CES2 gene promoter (830C>G) were studied as potential markers for SN-38 glucuronidation and irinotecan activation, respectively; and the potential activity of CYP3A4 was estimated from cortisol biotransformation into 6beta-hydroxycortisol. No pharmacokinetic parameter was directly predictive of clinical outcome or toxicity. The AUCs of three important metabolites of irinotecan, SN-38, SN-38 glucuronide and APC, were tentatively correlated with patients' pretreatment biological parameters related to drug metabolism (plasma creatinine, bilirubin and liver enzymes, and blood leukocytes). SN-38 AUC was significantly correlated with blood leukocytes number and SN-38G AUC was significantly correlated with plasma creatinine, whereas APC AUC was significantly correlated with plasma liver enzymes. The relative extent of irinotecan activation was inversely correlated with SN-38 glucuronidation. The TATA box polymorphism of UGT1A1 was significantly associated with plasma bilirubin levels and behaved as a significant predictor for neutropoenia. The level of cortisol 6beta-hydroxylation predicted for the occurrence of diarrhoea. All these observations may improve the routine use of irinotecan in colorectal cancer patients. UGT1A1 genotyping plus cortisol 6beta-hydroxylation determination could help to determine the optimal dose of irinotecan.

Phase I dose-escalation study of oral vinflunine administered once daily for 6 weeks every 8 weeks in patients with advanced/metastatic solid tumours.

PURPOSE: Vinflunine ditartrate is a microtubule inhibitor belonging to the vinca alkaloid family. This phase I study was carried out to evaluate the maximal tolerated dose, the safety profile, the pharmacokinetics and the activity of oral vinflunine (VFL) given daily in patients with advanced/metastatic solid tumours and who have failed standard therapy. METHODS: Patients were treated with oral VFL administered once daily for 6 weeks followed by a two-week rest. Sequential dose-escalating cohorts of patients were enrolled into 5 dose levels: 20, 40, 60, 75 and 95 mg/day. RESULTS: In total, 27 patients received 53 cycles. Dose-limiting toxicities (DLT) were observed from 60 mg/day. The dose levels 75 and 95 mg/day were both assessed as maximal tolerated dose. The most frequent dose-limiting toxicities were of haematological origin. The recommended dose was defined as 60 mg/day, dose at which 4 patients experienced long stabilizations (≥4 months) and also received longer treatment duration in comparison with the other dose levels. Blood exposure of VFL and its active metabolite 4-O-deacetyl vinflunine (DVFL) increased proportionally to the dose levels. The concentrations of VFL and DVFL reached a steady state at, respectively, 5 and 20 days and remained stable for the rest of the cycle. Increased incidence of DLT/SAE was consistent with the increase of VFL dose and drug exposure. CONCLUSIONS: These results showed the feasibility of daily oral vinflunine administration on a 6-week treatment duration. This new schedule of administrations enabled sustained and stable blood concentrations of both VFL and DVFL. The recommended dose was defined at 60 mg/day, dose at which 4 patients experienced clinical benefit.

Phase I dose-escalation study of vinflunine hard capsules administered twice a day for 2 consecutive days every week in patients with advanced/metastatic solid tumors.

BACKGROUND: Vinflunine is a new microtubule inhibitor of the vinca-alkaloid family. It is marketed in transitional cell carcinoma of urothelial tract as a 20 min infusion given every 3 weeks in Europe. METHODS: In this phase I study, vinflunine was administered to patients with advanced malignancies as hard capsules given twice a day on days 1-2 every week, with 3 weeks cycles. Serial blood samples were collected during the first cycle for pharmacokinetic investigations. RESULTS: Thirty-six patients (pts) were treated at 6 dose levels 150 (3 pts), 190 (3 pts), 230 (8 pts), 300 mg/day (6 pts) and then 250 (3 pts) and 270 mg/day (13 pts). The Maximal Tolerated Dose (MTD) was reached at 300 mg/day where 2 patients out of 6 experienced a dose limiting toxicity (febrile neutropenia with diarrhea). The lower dose level of 270 mg/day was the recommended dose (RD), the toxicity profile being mainly anaemia, neutropenia, fatigue and constipation. The pharmacokinetic analysis demonstrated the adequacy of the flat-fixed dosing regimen, as no correlation between clearance of vinflunine and body surface area was evidenced. Blood concentrations and exposure increased with dose, and a pharmacokinetic accumulation was observed, which is consistent with the terminal half-life of the compounds. The inter-individual exposure variability at the RD was 35%. CONCLUSION: Repeated weekly administration of oral vinflunine is feasible and exhibits a moderate inter-individual PK variability. The MTD was achieved at 300 mg/day given for 2 consecutive days. According to the protocol rules, the RD was established at 270 mg/day.