Sorafenib administered using a high-dose, pulsatile regimen in patients with advanced solid malignancies: a phase I exposure escalation study.

BACKGROUND: (Pre)clinical evidence is accumulating that intermittent exposure to increased doses of protein kinase inhibitors may improve their treatment benefit. In this phase I trial, the safety of high-dose, pulsatile sorafenib was studied. PATIENTS AND METHODS: High-dose sorafenib was administered once weekly in exposure escalation cohorts according to a 3 + 3 design. Drug monitoring was performed in weeks 1-3 and doses were adjusted to achieve a predefined target plasma area under the curve (AUC)(0-12 h). The effect of low gastric pH on improving sorafenib exposure was investigated by intake of the acidic beverage cola. RESULTS: Seventeen patients with advanced malignancies without standard treatment options were included. Once weekly, high-dose sorafenib exposure was escalated up to a target AUC(0-12 h) of 125-150 mg/L/h, achieving a twofold higher Cmax compared to standard continuous dosing. Dose-limiting toxicity was observed in three patients: grade 3 duodenal perforation (2800 mg sorafenib), grade 5 multiorgan failure (2800 mg sorafenib) and grade 5 biliary tract perforation (3600 mg sorafenib). The mean difference between observed and target AUC(0-12 h) was 45% (SD ± 56%) in week 1 using a fixed starting dose of sorafenib compared to 2% (SD ± 32%) in week 3 as a result of drug monitoring (P = 0.06). Dissolving sorafenib in cola, instead of water, did not improve sorafenib exposure. Clinical benefit with stable disease as the best response was observed in two patients. CONCLUSION: Treatment with high-dose, once weekly sorafenib administration resulted in dose-limiting toxicity precluding dose escalation above the exposure cohort of 125-150 mg/L/h. Drug monitoring was a successful strategy to pursue a target exposure.

Randomized phase 2 study of gemcitabine and cisplatin with or without vitamin supplementation in patients with advanced esophagogastric cancer.

PURPOSE: Preclinical research and prior clinical observations demonstrated reduced toxicity and suggested enhanced efficacy of cisplatin due to folic acid and vitamin B12 suppletion. In this randomized phase 2 trial, we evaluated the addition of folic acid and vitamin B12 to first-line palliative cisplatin and gemcitabine in patients with advanced esophagogastric cancer (AEGC). METHODS: Patients with AEGC were randomized to gemcitabine 1250 mg/m2 (i.v. days 1, 8) and cisplatin 80 mg/m2 (i.v. day 1) q 3 weeks with or without folic acid (450 µg/day p.o.) and vitamin B12 (1000 µg i.m. q 9 weeks). The primary endpoint was response rate (RR). Secondary endpoints included overall survival (OS), time to progression (TTP), toxicity, and exploratory biomarker analyses. Cisplatin sensitivity and intracellular platinum levels were determined in adenocarcinoma cell lines cultured under high and low folate conditions in vitro. RESULTS: Adenocarcinoma cells cultured in medium with high folate levels were more sensitive to cisplatin and this was associated with increased intracellular platinum levels. In the randomized phase 2 clinical trial, which ran from October 2004 to September 2013, treatment was initiated in 78 of 82 randomized pts, 39 in each study arm. The RR was similar; 42.1% for supplemented patients vs. 32.4% for unsupplemented patients; p = 0.4. Median OS and TTP were 10.0 and 5.9 months for supplemented vs. 7.7 and 5.4 months for unsupplemented patients (OS, p = 0.9; TTP, p = 0.9). Plasma homocysteine was lower in the supplemented group [n = 20, 6.9 ± 1.6 (mean ± standard error of mean, SEM) µM; vs. 12.5 ± 4.0 µM; p < 0.001]. There was no significant difference in the Cmax of gemcitabine and cisplatin in the two treatment groups. CONCLUSION: Folic acid and vitamin B12 supplementation do not improve the RR, PFS, or OS of cisplatin and gemcitabine in patients with AEGC.

Cell cycle effects and increased adduct formation by temozolomide enhance the effect of cytotoxic and targeted agents in lung cancer cell lines.

Temozolomide (TMZ) exerts its cytotoxic effects by methylating guanine in DNA, resulting in a mismatch with thymine. We studied possible enhancement of the cytotoxic activity of several other targeted drugs in four lung cancer cell lines by TMZ. the data are in relation to O(6)-alkylguanine-DNA-alkyltransferase (AGT) expression, gene methylation, cell cycle distribution and adduct formation. Synergism/additivity was found with O(6)-BG), gemcitabine, lonafarnib and paclitaxel, but not with platinum analogs and topoisomerase-inhibitors. O(6)-BG enhanced TMZ-induced accumulation in the G2/m-phase by increasing formation and retention of the O(6)-methyldeoxyguanosine adducts. TMZ combinations with drugs showing a different individual effect on the cell cycle (e.g. gemcitabine-induced S-phase) were most effective. The results show that O(6)-BG enhanced the TMZ effect in all cell lines. TMZ enhanced the cytotoxicity of gemcitabine, paclitaxel and lonafarnib in most cell lines, possibly by affecting the cell cycle, supporting possible application of TMZ in the treatment of lung cancer.

A phase I and pharmacokinetic study of gemcitabine given by 24-h hepatic arterial infusion.

PURPOSE: This study was performed to assess the toxicities, the maximum-tolerated dose (MTD), the pharmacokinetics and the anti-tumour activity of gemcitabine given by 24-h hepatic arterial infusion (HAI). PATIENTS AND METHODS: Patients with liver malignancies received gemcitabine by 24-h HAI, weekly x 3, every 4 weeks. On day 1 or day 8 of the first cycle, patients received one administration by 24-h intravenous infusion for pharmacokinetic comparison and to determine hepatic extraction. RESULTS: Thirteen patients received gemcitabine at the dose levels of 75, 135 and 180 mg/m(2). The MTD was 180 mg/m(2) with thrombocytopaenia as the dose-limiting toxicity. Pharmacokinetic analysis showed a significantly lower maximum gemcitabine plasma concentration (C(max): HAI, 26, 80 and 128 nM, respectively; IV, 229, 264 and 293 nM, respectively) and area under the plasma-concentration-versus-time curve (AUC(0-24h): HAI, 386, 1247 and 2033 nmol x h/L, respectively; IV, 3526, 4818 and 5363 nmol x h/L, respectively) during HAI, compared with intravenous infusion (both P<0.001). Additionally, the mean hepatic extraction ratios of gemcitabine at the 75, 135 and 180 mg/m(2) dose level were 0.89, 0.75 and 0.55, respectively. Hepatic extraction decreased linearly with increasing dose. The C(max) and AUC(0-24h) of 2',2'-difluoro-2'-deoxyuridine, the deaminated product of gemcitabine, were similar for HAI and intravenous infusion. Seven patients had stable disease for a median duration of 9 months (range: 2-11 months). CONCLUSIONS: Gemcitabine given by 24-h HAI was well tolerated and resulted in significantly lower systemic gemcitabine plasma concentrations than intravenous infusion due to a relatively high hepatic extraction.

Gemcitabine uptake in glioblastoma multiforme: potential as a radiosensitizer.

Glioblastoma multiforme (GBM), the most frequent malignant brain tumor, has a poor prognosis, but is relatively sensitive to radiation. Both gemcitabine and its metabolite difluorodeoxyuridine (dFdU) are potent radiosensitizers. The aim of this phase 0 study was to investigate whether gemcitabine passes the blood-tumor barrier, and is phosphorylated in the tumor by deoxycytidine kinase (dCK) to gemcitabine nucleotides in order to enable radiosensitization, and whether it is deaminated by deoxycytidine deaminase (dCDA) to dFdU. Gemcitabine was administered at 500 or 1000 mg/m(2) just before surgery to 10 GBM patients, who were biopsied after 1-4 h. Plasma gemcitabine and dFdU levels varied between 0.9 and 9.2 microM and 24.9 and 72.6 microM, respectively. Tumor gemcitabine and dFdU levels varied from 60 to 3580 pmol/g tissue and from 29 to 72 nmol/g tissue, respectively. The gene expression of dCK (beta-actin ratio) varied between 0.44 and 2.56. The dCK and dCDA activities varied from 1.06 to 2.32 nmol/h/mg protein and from 1.51 to 5.50 nmol/h/mg protein, respectively. These enzyme levels were sufficient to enable gemcitabine phosphorylation, leading to 130-3083 pmol gemcitabine nucleotides/g tissue. These data demonstrate for the first time that gemcitabine passes the blood-tumor barrier in GBM patients. In tumor samples, both gemcitabine and dFdU concentrations are high enough to enable radiosensitization, which warrants clinical studies using gemcitabine in combination with radiation.