Search

There is controversy over the role of Her-2 in osteosarcoma, with some investigators reporting association between expression and adverse outcome, whereas others point to the lack of gene amplification and membranous expression by immunohistochemistry (IHC) as inconsistent with biological significance. Her-2 normally requires pairing with epidermal growth factor receptor (EGFR), Her-3, or Her-4, but these have been less well studied in osteosarcoma. We evaluated the expression of each of these receptors in osteosarcoma and their potential to contribute to pathogenesis by examining a panel of low-passage primary osteosarcoma cell lines, comparing these with archival tumor specimens. Her-2 immunoreactivity was seen frequently in the diffuse staining pattern described previously. We observed EGFR in all samples by IHC. Her-3 expression was not observed. Her-4 expression was nuclear in distribution in all tumor samples and many cell line samples, consistent with activation and cleavage of the receptor. Quantified expression of Her-2 and EGFR mRNA by quantitative, real-time PCR in cell lines correlated with IHC for Her-2 but not for EGFR. Western blot identified full-length receptors for EGFR and Her-2 in all expected cell lines and showed Her-4 to be predominantly in the p80 form. Flow cytometry identified cell surface Her-2 and EGFR in all lines with receptor expression by IHC. We conclude that the cell surface expression of Her-2 and EGFR and the nuclear localization of the activated p80 fragment of Her-4 suggest that all three may be contributing to osteosarcoma pathogenesis. Therapy directed against this family of receptors may be beneficial for patients with osteosarcoma.

Pharmacokinetic studies of 5-fluorouracil (5-FUra) were performed on 18 patients divided into three groups: seven patients were given 5-FUra i.v. by rapid injection; five patients received the drug p.o.; and six patients were treated by continuous i.v. infusion for 96 hr. The results showed rapid i.v. injection to be manifested by high early levels of drug achieved both in plasma and bone marrow with a rapid fall afterwards. Administration of 5-FUra p.o. gave rise to erratic plasma values due to greater variability in absorption, whereas 96-hr i.v. infusions showed constant levels of the drug in plasma and significantly (50- to 1000-fold) less 5-FUra in bone marrow. The main difference observed between rapid injection and slow infusion in the kinetics of the drug was the very high level of 5-FUra reached by rapid injection in plasma and bone marrow, which was of short duration (min) when compared to the low sustained levels observed during infusion. This route-dependent pharmacokinetic profile is consistent with the reported absence of myelosuppression in prolonged infusion and may be related to the resultant lower levels of 5-FUra achieved in bone marrow.

Quinone derivatives have shown intensive antitumor activity in a broad variety of neoplasias. Aziridinylbenzoquinone is designed to have adequate lipid solubility to attain useful drug concentrations in the central nervous system. A Phase I study of aziridinylbenzoquinone was conducted in 32 patients with advanced solid cancers. The drug was given as a slow i.v. injection on Days 1, 8, 15, and 22 of a 42-day cycle with a 2-week rest. Five dose levels ranging from 5 to 20 mg/sq m were studied, with 3 to 10 patients treated at each level; a total of 156 doses were administered. The major toxicity was myelosuppression with the median nadir in platelet and white blood cells occurring at Days 15 to 27 of the cycle, and first appearing at doses greater than 10 mg/sq m. Anemia was first seen at the 10-mg/sq m dose level, occurring between Days 22 and 40. Nonmyelosuppressive toxic effects included nausea and vomiting, anorexia, diarrhea, stomatitis, slight alopecia, and transient fever. The highest tolerated dose was 20 mg/sq m, the recommended dose for Phase II studies. Plasma and urine pharmacokinetics were studied in 17 patients by a high-pressure liquid chromatography method. Plasma decay curves could be fitted to a two-compartment open-system model with an overall average alpha and beta half-life values of 10.5 +/- 6.28 min and 16.90 +/- 8.63 (S.D.) hr. Aziridinylbenzoquinone levels were determined in urine samples of 12 patients, but less than 0.1% of the dose was excreted in the 0- to 4-hr sample of two patients, and none was detected in the urine of 10 patients.

Phase I evaluation of spiromustine was performed using an every-3-week schedule and a weekly X 3 schedule. Neurotoxicity was the dose-limiting toxicity presenting as alterations in cortical integrative functions (orientation, language, coordination), leading to a decrease in the level of consciousness. Traditional criteria for grading neurotoxicity poorly characterized these toxicities. The maximum tolerated dose was 6 mg/m2 every 3 weeks and 3 mg/m2 weekly X 3. Concurrent murine studies confirmed spiromustine as a schedule independent drug with toxicity correlating with peak plasma levels. Physostigmine had little effect on decreasing neurotoxicity in the murine model. The solvating agent used was not responsible for the neurotoxicity. Injection of spiromustine on a split-dose schedule decreased the acute neurological toxicity in mice and allowed a larger total dosage to be delivered (compared to single bolus dosage). Based on these results a split-dose schedule is suggested for future clinical trials.

Tricyclic nucleoside phosphate (TCN-P) was selected for clinical trials because of its unusual chemical structure and activity against L1210 murine leukemia and MX-1 mammary xenograft. Inhibiting DNA synthesis, TCN-P was more toxic during S-phase of cell cycle. A phase I study was conducted in 24 patients with advanced solid cancers. The drug was given as a slow i.v. injection over 5 min on Days 1, 8, 15, and 22 of a 42-day cycle with a 2-week rest. Five dose levels ranging from 12 to 96 mg/m2 were studied with 3 to 12 patients treated at each level; a total of 106 doses was administered. The major hematological toxicity was thrombocytopenia, with a median nadir occurring at Day 34 of the cycle and first appearing at doses greater than 24 mg/m2. Anemia was seen at each dose level occurring between Days 8 and 34. Non-myelosuppressive toxic effects included stomatitis, anorexia, transient fever, nausea and vomiting, and dose-limiting hyperglycemia and diarrhea. The highest tolerated dose was 48 mg/m2. Plasma, pleural fluid, urine, and tissue samples were analyzed for TCN-P and tricyclic nucleoside (TCN) in selected patients by high-performance liquid chromatography. Plasma decay curves revealed extended retention of both TCN and TCN-P. Autopsy specimens obtained 61 days after therapy showed the highest residues of TCN-P in liver metastases and of TCN in gall bladder, bile, and pancreas. No drug was detected in urine samples of two patients. Prolonged retention and erratic plasma levels of the drug are probably due to extensive enterohepatic circulation, as well as repeated interconversion between TCN-P and TCN within cells. This weekly schedule produced unexpected clinical toxicity and should not be pursued.

Acodazole (NSC 305884) was examined in a Phase I trial evaluating a 1-h infusion repeated every 21 days in 37 patients with advanced carcinomas. Cardiac toxicity was dose-limiting at 1370 mg/m2, manifested as multiple premature ventricular contractions, QTc interval prolongation, and decreasing heart rate. Other toxicities included mild to moderate nausea and vomiting and local reaction near the i.v. injection site requiring the use of central venous catheters. Antineoplastic activity was not observed. Acodazole levels assayed by high-performance liquid chromatography disclosed a peak plasma level of 19 +/- 4 (SEM) micrograms/ml for 1370 mg/m2. Acodazole plasma levels decreased in a triphasic manner over a 100-fold range. The volume of distribution at steady state was 238 +/- 18 liter/m2 suggesting extensive tissue binding. The total body clearance was 13.6 +/- 0.9 liter/h/m2; the percentage of urinary excretion was 29 +/- 2% for 48 h. To evaluate cardiac toxicity, acodazole was administered to five dogs at 2262 mg/m2 (1-h infusion) which provided plasma concentrations similar to those achieved at 1370 mg/m2 in humans. Consistent findings in dogs were drug-related prolongation of QTc intervals, and reduction in heart rate, left ventricular dP/dt, and mean blood pressures. Clinical development of acodazole requires studies to further elucidate and alleviate this cardiac toxicity.