Ephrin A5 expression promotes invasion and transformation of murine fibroblasts.

Emerging evidence suggests involvement of the ephrin/Eph receptor system in tumourigenesis. Research on this new role has centred on the contribution of Eph receptors. In contrast, we focused on the elucidation of the role of ephrins, specifically ephrin A5. Results indicated an increase in invasive potential of ephrin A5-expressing murine fibroblasts, which was abolished by addition of a Src family kinase inhibitor. Furthermore, anchorage-independent growth was increased in ephrin A5-expressing cells. Stimulation with EphA5-Fc receptor increased colony size, but not colony number in ephrin A5 transfectants. Moreover, we observed morphogenetic transformation of ephrin A5-expressing 3T3 cells into a branching network when plated onto Matrigel. This behaviour was specific to ephrin A5 transfectants, as 3T3 cells expressing ephrin B1 displayed a phenotype similar to control 3T3 cells. We conclude that ectopic expression of ephrin A5 in murine fibroblasts elevates oncogenic potential, including increased invasive behaviour, anchorage-independent growth, and morphological transformation.

HIV TAT variants differentially influence the production of glucocerebrosidase in Sf9 cells

Gaucher disease, the most common lysosomal storage disorder, is currently treated with enzyme replacement therapy. This approach, however, is ineffective in altering the progression of neurodegeneration in type 2 and type 3 patients due to the difficulty of transferring the recombinant enzyme across the blood-brain barrier. Human immunodeficiency virus type 1 trans-activating transcriptional activator protein (HIV TAT) contains a protein transduction domain that can be added to a fusion protein partner to allow for transport of the partner across membranes. Consequently, we examined the creation, production, and secretion of fusion constructs containing glucocerebrosidase and either wild-type TAT or modified TAT in Sf9 cells. All three constructs exhibited successful expression, with wild-type TAT chimeras showing lower levels of expression than modified TAT chimeras.

Targeted antiangiogenic therapy for cancer using Vitaxin: a humanized monoclonal antibody to the integrin alphavbeta3.

Angiogenesis plays a central role in the growth and metastasis of cancers. Strategies aimed at interfering with tumor blood supply offer promise for new cancer therapies. Vitaxin (an anti-alphavbeta3 antibody) interferes with blood vessel formation by inducing apoptosis in newly generated endothelial cells. This Phase I study evaluates the safety and pharmacokinetics of Vitaxin in humans with cancer. Eligible patients demonstrated progressive tumors with stage IV disease and an Eastern Cooperative Oncology Group performance status < or =2. Treatment consisted of six weekly infusions of Vitaxin. Escalating doses from 0.1 and 4.0 mg/kg/week were evaluated based on the expectation that plasma levels would bracket the effective in vitro concentration. Escalation beyond 4 mg/kg/week was limited by drug availability. Adverse events were assessed weekly. Pharmacokinetics were performed weekly through week 9. Clinical response was assessed at week 9. Of 17 patients treated, 14 were evaluable for response. Treatment was well tolerated with little or no toxicity. The most common side effect was infusion-related fever, which could be controlled with prophylactic antipyretics. Doses > or =1 mg/kg/week produced plasma concentrations sufficient to saturate the alphavbeta3 receptor in vitro (25 microg/ml). Vitaxin demonstrated a half-life in excess of 5 days at higher doses with no accumulation over 6 weeks of therapy. One patient demonstrated a partial response, and seven patients demonstrated stable disease. Three patients received Vitaxin beyond the first cycle of therapy. Each of these patients demonstrated disease stabilization that in one case lasted 22 months. At the doses and schedule studied, Vitaxin appears safe and potentially active, suggesting that vascular integrin alphavbeta3 represents a clinically relevant antiangiogenic target for prolonged cancer therapy.

Alternating combination chemotherapy for stages III and IV ovarian carcinoma.

Thirty-nine previously untreated patients with stages III and IV ovarian carcinoma were treated with debulking surgery, followed by alternating combination chemotherapy with cisplatin, Adriamycin (Adria Laboratories, Columbus, Ohio), and cyclophosphamide (PAC); and hexamethylmelamine, cyclophosphamide, methotrexate, and 5-fluorouracil (HexaCAF). Of 19 patients with measureable disease at the onset of therapy, ten (53%) had at least a partial response to chemotherapy. Seven (18% of total) patients were found to be pathologically free of disease at secondlook surgery, but four patients relapsed 19 to 31 months after initiating therapy. The median progression-free survival period of all 39 patients entered into the study is 12 months, and the median crude survival is 21 months. The PAC/HexaCAF alternating combination chemotherapy regimen may be administered with moderate toxicity, but the treatment results are not superior to those reported for PAC or HexaCAF alone in advanced ovarian carcinoma.

Clinical pharmacokinetics of intraarterial cisplatin in humans.

The pharmacokinetics of intraarterially administered cisplatin (DDP) were studied in three patients with large hepatic tumors, and one patient with a fibrous histiocytoma in the thigh, using an assay sensitive to only those forms of non-protein bound DDP capable of reacting with the nucleophilic ligand diethyldithiocarbamate. Each patient received continuous intravenous and intraarterial infusions at various dose rates, with and without concurrent infusion of the neutralizing agent sodium thiosulfate. Steady-state DDP concentrations were achieved within two hours, and the mean (+/- SEM) plasma clearance at infusion rates of 5-15 mg/m2 per hour was 345 +/- 45 mL/m2 per minute. Apparent plasma clearance did not vary significantly with route of infusion. Based on the plasma clearance, predicted values for the relative advantage of an intraarterial infusion (Rt) were less than two for hepatic infusion; observed values averaged 1.9 +/- 0.5 (+/- SEM). The infusion of thiosulfate did not significantly increase plasma clearance. The mean (+/- SEM) extraction ratio for hepatic infusions was 0.24 +/- 0.09, and for infusion of the peripheral soft tissue sarcoma it was 0.27 +/- 0.03. These data indicate that from the point of view of both the tumor and the systemic circulation there is only a limited pharmacologic advantage for intraarterial infusion of DDP into organs with plasma flows of greater than 350 mL/m2 per minute.

High-dose allopurinol modulation of 5-FU toxicity: phase I trial of an outpatient dose schedule.

In an attempt to decrease the activation of 5-FU by normal cells relative to cancer cells, 20 patients with metastatic cancer were given 72 courses of 5-FU and allopurinol (HPP) in a phase I trial. 5-FU was given daily by iv bolus injection for 5 consecutive days every 4 weeks: HPP, 300 mg orally every 8 hours for 6 consecutive days, was started 24 hours before the first injection of 5-FU. HPP appeared to modulate 5-FU toxicity by allowing higher doses (18-21 mg/kg daily for 5 days) to be given. Unexpectedly, neurotoxicity was the dose-limiting toxicity; it was slowly reversible and manifested primarily as encephalopathy, with some patients having cerebellar signs. Gastrointestinal and hematologic toxic effects were mild and infrequent. Because of the high incidence of neurotoxicity and low response rate, this program does not appear to offer any advantages over conventional dose schedules of 5-FU alone.