Phase I study of nanoliposomal irinotecan (PEP02) in advanced solid tumor patients

Purpose

To define the dose-limiting toxicity (DLT), maximum tolerated dose (MTD) and pharmacokinetics (PK) of PEP02, a novel liposome-encapsulated irinotecan, in patients with advanced refractory solid tumors.

Methods

Patients were enrolled in cohorts of one to three to receive escalating dose of PEP02 in a phase I trial. PEP02, from 60 to 180 mg/m², was given as a 90-min intravenous infusion, every 3 weeks.

Results

A total of 11 patients were enrolled into three dose levels: 60 (one patient), 120 (six patients) and 180 mg/m² (four patients). DLT was observed in three patients, one at 120 mg/m² (grade 3 catheter-related infection) and two at 180 mg/m² (grade 4 neutropenia lasting for >3 days in one, grade 4 hematological toxicities and grade 4 diarrhea in the other). MTD was determined as 120 mg/m². Comparing with those after free-form irinotecan in the literature, the dose-normalized PK of SN-38 (the active metabolite) after PEP02 was characterized by lower C_max, prolonged terminal half-life and higher AUC but with significant inter-individual variation. One patient who died of treatment-related toxicity had significantly higher C_max and AUC levels of SN-38 than those of the other three patients at 180 mg/m². Post hoc pharmacogenetic study showed that the patient had a combined heterozygosity genotype of UGT1A1*6/*28. Two patients had objective tumor response.

Conclusions

PEP02 apparently modified the PK parameters of irinotecan and SN-38 by liposome encapsulation. The MTD of PEP02 monotherapy at 3-week interval is 120 mg/m², which will be the recommended dose for future studies.

Randomized, phase I, and pharmacokinetic (PK) study of RAD001, an mTOR inhibitor, in patients (pts) with advanced hepatocellular carcinoma (HCC)

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Background: RAD001, an orally administered, novel mTOR inhibitor has recently been extensively evaluated in cancer therapy. Up-regulation of mTOR expression has been noted in 40–45% of HCC, and preclinical studies suggest mTOR inhibitor can effectively inhibit proliferation of HCC cells as well as growth of HCC xenograft in mice. In addition, cytochrome P450 system is known to involve in metabolism of rapamycin analogues, and elimination of RAD001 is impaired in pts with hepatic dysfunction. The study aims to define the dose-limiting toxicity (DLT), maximum tolerated dose (MTD) and PK of daily- and weekly-dosing RAD001 in advanced HCC pts. Methods: Advanced HCC pts who were not feasible for or progressed after local therapy (surgery, percutaneous ablation or transcatheter arterial chemoembolization), ECOG PS 0–2, Child-Pugh's score < 8, and adequate hepatic, renal and hematological functions were eligible. The doses of RAD001 for daily-dosing arm would be escalated from 2.5, 5.0, 7.5 to 10.0 mg, and from 20, 30, 50 to 70 mg in weekly-dosing arm. Four weeks of treatment was regarded as one cycle. PK samples were collected on days 1 of cycle 1 and 2. Results: A total of 36 pts (M/F 34/2; median age 58.5, range 28–75; Child-Pugh's class of A/B 31/5) were enrolled. Number of pts with DLT/enrollment for dose level I, II, III and IV in daily arm was 1/6 (grade 3 hyperbilirubinemia), 1/6 (grade 4 thrombocytopenia), 0/3 and 2/3 (grade 3 diarrhea and rectal bleeding in 1 and grade 3 diarrhea and cardiac ischemia in 1), respectively; whiles in weekly arm was 0/3, 1/6 (grade 3 ALT elevation), 0/3 and 1/6 (grade 3 infection), respectively. MTD for weekly- and daily- dosing schedule was 70 mg and <7.5 mg, respectively. Reactivation of HBV and HCV was observed in 4 and 1 pts, respectively. The disease control response (DCR) of 31 evaluable pts was 61% (10/16) and 46.7% (7/15, including one PR) of pts receiving daily and weekly treatment, respectively. However, the DCR for weekly-dosing pts received >50 mg was 75% (4/6). Conclusions: Patient accrual is ongoing to complete. However, preliminary data suggest RAD001 is moderately active in stabilizing the progression of HCC, and PK data will be important to determine the optimal dosing schedule of RAD001 for HCC pts.

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Pseudomonas exotoxin A-epidermal growth factor (EGF) mutant chimeric protein as an indicator for identifying amino acid residues important in EGF-receptor interaction

Epidermal growth factor (EGF) was fused to the carboxyl end of a modified pseudomonas exotoxin A that has its toxin binding domain deleted. This chimeric toxin designated as PE(delta Ia)-EGF kills A431 cells through the EGF receptor-mediated pathway. In this study, we used a random mutagenesis approach to make point mutations on EGF, followed by replacing the wild type EGF in PE(delta Ia)-EGF with these EGF mutants. We have constructed 14 different PE(delta Ia)-EGFmutants, and examined their EGF receptor binding activity as well as their cytotoxicity to A431 cells. Our results showed that individual mutations of Val19 to Glu and Val34 to Asp in the EGF domain of PE(delta Ia)-EGFmutants resulted in an increase in the binding affinity to EGF receptor and cytotoxicity to A431 cells. On the other hand, individual mutations of His16 to Asp and Gly18 to Ala in the EGF domain of PE(delta Ia)-EGFmutants lead to a decrease in the binding affinity to EGF receptor and cytotoxicity to A431 cells. In addition, mutations of any of the cysteine residues of EGF in PE(delta Ia)-EGFmutants resulted in the loss of their binding activity to EGF receptor and a corresponding loss of their cytotoxicity. This study indicates that the cytotoxicity of PE(delta Ia)-EGFmutant to EGF receptor-bearing cells may be used as an indicator to screen mutations of EGF important in EGF-receptor interactions.

Modulatory effect of crocetin on aflatoxin B1 cytotoxicity and DNA adduct formation in C3H10T1/2 fibroblast cell

Crocetin is a carotenoid isolated from the seeds of Cape jasmine (Gardenia jasminoides). The cytotoxicity and DNA-adduct formation of rat microsome-activated aflatoxin B1 (AFB1) in the C3H10T1/2 cells were significantly inhibited by pretreatment of crocetin. Most significant inhibition was found at the time of 9 h after crocetin pretreatment. Under these experimental conditions, consistent elevation in the cytosolic glutathione (GSH) levels and the activities of GSH S-transferase (GST) and GSH-peroxidase (GSH-Px) were observed. Crocetin treatment also resulted in a decrease in AFB1-DNA adduct formation in vitro, while no effect of crocetin on the formation of AFB1-8,9-oxide in vitro system was detected as measured by the Trisdiol method. From these results, we suggested that the protective effect of crocetin on the AFB1-cytotoxicity in C3H10T1/2 cells might be due to the cellular defense mechanisms that elevated the cytosol GSH and the activities of GST and GSH-Px.

Effect of ethanol on hepatotoxicity and hepatic DNA-binding of aflatoxin B1 in rats

The hepatocarcinogen aflatoxin B1 is converted to reactive metabolites that bind covalently to cellular macromolecules. These metabolites may also react with glutathione, resulting in the formation of glutathione conjugates and detoxication of the reactive metabolite. When rats were pretreated with ethanol by gastric intubation at a dose of 100 mmol/kg, 6 hr (the time of maximal GSH depletion) before the administration of aflatoxin B1, the covalent binding of 8,9-epoxide-aflatoxin B1 to DNA in vivo was increased by 47% and the hepatotoxicity was also potentiated. However, the covalent binding was not increased by pretreatment with ethanol 18 hr (time with approximately normal GSH levels) before administration of the toxin, and no potentiation of hepatotoxicity was observed. Pretreatment with a non-toxic dose of ethanol had no effects on the activity of glutathione S-transferase and glutathione peroxidase. These results suggest that the depletion of GSH and the increased formation of DNA-adduct from the liver constitute an important mechanism for the potentiation of aflatoxin B1-induced hepatotoxicity by ethanol.