Phase II and pharmacokinetic study of ecteinascidin 743 in patients with progressive sarcomas of soft tissues refractory to chemotherapy.

PURPOSE: To assess the efficacy of the marine-derived alkaloid ecteinascidin 743 (ET-743) in patients with soft tissue sarcomas that progressed despite prior conventional chemotherapy and to characterize the pharmacokinetic profiles of ET-743 in this patient population. PATIENTS AND METHODS: Thirty-six previously treated soft tissue sarcoma patients from three institutions received ET-743 as a 24-hour continuous intravenous (IV) infusion at a dose of 1,500 microg/m(2) every 3 weeks. Pharmacokinetic studies were also performed. Patients were restaged every two cycles for response by objective criteria. RESULTS: Objective responses were observed in three patients, with one complete response and two partial responses, for an overall response rate of 8% (95% CI, 2% to 23%). Responses were durable for up to 20 months. Two minor responses (43% and 47% tumor reduction) were observed, for an overall clinical benefit rate of 14%. The predominant toxicities were neutropenia and self-limited transaminitis of grade 3 to 4 severity in 34% and 26% of patients, respectively. The estimated 1-year time to progression and overall survival rates were 9% (95% CI, 3% to 27%) and 53% (95% CI, 39% to 73%), respectively. The maximum observed plasma concentration and total plasma clearance of ET-743 (mean +/- standard deviation), 1.04 +/- 0.48 ng/mL and 35.6 +/- 16.2 L/h/m(2), respectively, were consistent with previously reported values from phase I studies of the drug given as a 24-hour IV infusion. CONCLUSION: ET-743 is a promising new option for the management of several histologic subtypes of sarcoma. Durable objective responses were obtained in a subset of sarcoma patients with disease progression despite prior chemotherapy. Additionally, the relatively high survival rate noted in this series of previously treated patients further justifies development of this agent.

High-throughput sequence identification of gene coding variants within alcohol-related QTLs.

Low initial response to alcohol has been shown to be among the best predictors of development of alcoholism. A similar phenotypic measure, difference in initial sensitivity to ethanol, has been used for the genetic selection of two mouse strains, the Inbred Long-Sleep (ILS) and Inbred Short-Sleep (ISS) mice, and for the subsequent identification of four quantitative trait loci (QTLs) for alcohol sensitivity. We now report the application of high throughput comparative gene sequencing in the search for genes underlying these four QTLs. To carry out this search, over 1.7 million bases of comparative DNA sequence were generated from 68 candidate genes within the QTL intervals, corresponding to a survey of over 36,000 amino acids. Eight central nervous system genes, located within these QTLs, were identified that contain a total of 36 changes in protein coding sequence. Some of these coding variants are likely to contribute to the phenotypic variation between ILS/ISS animals, including sensitivity to alcohol, providing specific new genetic targets potentially important to the neuronal actions of alcohol.

Stabilisation of collagen by betel nut polyphenols as a mechanism in oral submucous fibrosis.

Treatment of reconstituted collagen fibrils and pieces of rat dermis with the crude extract, purified tannins or (+)-catechin from betel nut (Areca catechu) increases their resistance to both human and bacterial collagenases in a concentration-dependent manner. These tanning agents may stabilise collagen in vivo following damage to the oral epithelium, and promote the sub-epithelial fibrosis which occurs in betel nut chewers.

An in-vitro comparison of human fibroblasts from normal and oral submucous fibrosis tissue.

Fibroblasts cultured in vitro from normal buccal tissue and from tissue from oral submucous fibrosis (OSF) associated with betel-nut chewing showed no significant difference in their rates of proliferation in culture, nor in the rate at which they hydrolysed the betel nut alkaloid arecoline to arecaidine. Basal rates of collagen synthesis were slightly higher in the OSF cells but, on addition of arecoline, the rate of collagen synthesis in normal and OSF cells was stimulated to the same level.

Stimulation of human buccal mucosa fibroblasts in vitro by betel-nut alkaloids.

Oral submucous fibrosis (OSF) is characterized by excessive collagen production by mucosal fibroblasts and is associated with the habitual chewing of betel-nuts (Areca catechu); nut extracts stimulate fibroblast activity in vitro. The metabolism of arecoline, the major alkaloid in the nut, by human buccal mucosa fibroblasts in vitro was investigated; alkaloid metabolites extracted from culture media were analysed by gas chromatography and thin-layer chromatography. [3H]-arecoline was metabolized predominantly to [3H]-arecaidine and this was accompanied by a concentration-dependent stimulation of collagen synthesis and cell proliferation. Arecaidine was a more potent stimulator than arecoline. The rate of hydrolysis of a series of synthetic arecaidine esters (methyl, ethyl, butyl, propyl and pentyl) by fibroblasts was closely correlated with the extent of stimulation of collagen synthesis. Thus fibroblasts are responsive to the major metabolite of arecoline and hydrolysis of the ester group may be necessary for this action. Exposure of buccal mucosa fibroblasts to these alkaloids in vivo may contribute to the accumulation of collagen in OSF.

Ultrastructural findings of muscle degeneration in oral submucous fibrosis.

Muscle changes were investigated ultrastructurally in 2 groups of patients having oral submucous fibrosis. One group was from patients with no evidence of restricted mouth opening and the other was from patients with restricted mouth opening. Electronmicroscopically, the majority of muscle fibres taken from the first group appeared normal with only occasional muscle fibres showing accumulation of homogeneous material and compression of the sarcomeres closest to this material. In contrast, the tissues from patients with restricted mouth opening showed severe changes and necrosis in a high proportion of muscle fibres. The necrotic muscle fibres exhibited complete loss of their plasma membrane, but in which the outline was maintained by an intact basal lamina. It is suggested from this study that restricted mouth opening in submucous fibrosis might depend not only on the subepithelial fibrosis but also on the extent of muscle degeneration.

HLA-typing in oral submucous fibrosis.

Oral submucous fibrosis (OSF) is a disease of the mouth and oropharynx characterised by progressive deposition of collagen leading to severe limitation of movement of the jaw in advanced cases. It is almost completely confined to inhabitants of, or migrants from India who chew 'betel nut'. The histopathological and clinical features suggest that autoimmune mechanisms may be involved. Because all chronic autoimmune diseases show disturbance in the frequencies of HLA antigens, we have HLA typed 50 OSF patients and a similar number of healthy subjects of the same ethnic origin. Raised frequencies of A10 and DR3 were observed. The results support the concept that OSF is a chronic autoimmune disease, initiated by constituents of betel nut, and occurring in genetically susceptible individuals. Genes situated in the HLA region are important determinants of genetic susceptibility in OSF.

The aetiology of oral submucous fibrosis: the stimulation of collagen synthesis by extracts of areca nut.

Oral submucous fibrosis is a chronic disabling disease developing in up to 0.5% of the estimated 500 million habitual chewers of the "betel" quid. The quid, or chew, usually comprises a leaf of the Piper betel vine in which is wrapped fragments of the nut of Areca catechu, together with slaked lime and varied additives, including tobacco. The precise aetiology of oral submucous fibrosis (OSF) remains obscure, but epidemiological and animal studies have pointed to a close association with the prolonged usage of A. catechu nuts. Epithelial atypia and epidermoid carcinoma have been reported in 15% and 7%, respectively, of patients with established OSF. Preparations from varieties of A. catechu nuts have been tested for their ability to stimulate collagen synthesis in microwell cultures of human fibroblasts, using a pulse of 3H-proline and subsequent analysis of the cultures for radioactive collagen. Crude extracts of three varieties of areca nuts were extracted with ethanol and lyophilised before dilution in the culture medium. Control media contained identical concentrations of ethanol where appropriate. The three extracts at a concentration of 10 micrograms/ml stimulated collagen synthesis by approximately 150%, suggesting that this effect might be involved in the aetiology of oral submucous fibrosis.