Metastases and the normalization of tumour blood vessels by ICRF 159: a new type of drug action.

Profound modification of the structure and arrangement of the blood vessels has been shown in tumours after treatment with ICRF 159. X-ray angiography, carbon black (Pelikan ink) labelling, and intravital staining with lissamine green were used to demonstrate the changes. Alteration of the morphology of the blood vessels at the edge of a tumour may affect the escape of malignant cells and the rate of blood flow (and thus the concentration of anticancer drugs) through the tumour.

Topical tea tree oil effective in canine localised pruritic dermatitis--a multi-centre randomised double-blind controlled clinical trial in the veterinary practice.

Tea tree oil, a volatile oil, is well known for its broad antibacterial and antifungal activity. A standardised and stabilised 10% tea tree oil cream was tested against a commercial skin care cream (control cream) in the management of canine localised acute and chronic dermatitis. Fifty-seven dogs with clinical manifestations of mostly pruritic skin lesions or alterations, skin fold pyodermas and other forms of dermatitis, corroborated by predominantly positive fungal and bacterial skin isolates, were enrolled by seven practising veterinarians and randomly allocated to two study groups (28:29) and were treated twice daily with a blinded topical preparation. After 10 days of treatment, success rates of 71% for the tea tree oil cream and 41% for the control cream (over-all efficacy documented by the veterinary investigator) differed significantly (p = 0.04), favouring tea tree oil cream treatment. Accordingly on day 10, the tea tree oil cream caused significantly faster relief than the control cream (p = 0.04) for two common clinical dermatitis signs, pruritus (occurring in 84 % of dogs) and alopecia. Only one adverse event was reported in the tea tree oil group (suspected not to be causally related to the study drug) and none in the control cream group. The tested herbal cream appears to be a fast-acting safe alternative to conventional therapy for symptomatic treatment of canine localised dermatitis with pruritus.

Dexrazoxane significantly impairs the induction of doxorubicin resistance in the human leukaemia line, K562.

Dexrazoxane combined with doxorubicin (+ 5-fluorouracil + cyclophosphamide - the FAC regime) leads to a significant decrease in doxorubicin cardiotoxicity and a significant increase in median survival time for patients with advanced breast cancer responsive to FAC. The reason for this increase in survival may be due to interference with the mechanism involved in the emergence of multidrug resistance (MDR). In order to test this hypothesis, we induced resistance to doxorubicin in the K562 cell line by growing cells in increasing concentrations of doxorubicin (10-30 nM) in the presence and absence of dexrazoxane (20 nM). The doxorubicin sensitivity of all resultant sublines was measured using the MTT assay. Flow cytometry was used to assess the MDR1 phenotype, measuring P-glycoprotein expression with MRK 16 antibody and drug accumulation in the presence and absence of PSC 833 for functional P-glycoprotein. Long-term growth in doxorubicin increased the cellular resistance (IC(50)) of K562 cells in a concentration-dependent manner (r(2 )= 0.908). Doxorubicin resistance was not induced in the presence of dexrazoxane (P< 0.0001) for several months. In parallel, the expression of functional P-glycoprotein was delayed after concomitant addition of dexrazoxane to the selecting medium (P< 0.001). Dexrazoxane did not act as a conventional modulator of P-glycoprotein. These results suggest that dexrazoxane may delay the development of MDR1, thus allowing responders to the FAC regime to continue to respond.

Gadolinium as an opener of the outwardly rectifying Cl(-) channel (ORCC). Is there relevance for cystic fibrosis therapy?

There is indirect evidence that the plasmalemma-integrated eukaryotic porin (the voltage-dependent anion-selective channel, VDAC) functions as the outwardly rectifying chloride channel (ORCC). The channel, which is believed to play a role in cell volume regulation, appears to be relevant for cystic fibrosis (CF) therapy, in that it may function as an alternative Cl(-) channel. In the present study we showed first that Gd(3+) altered the voltage dependence of human type-1 porin incorporated into artificial planar lipid bilayers. Next, using a light-scattering approach on transformed normal or CF human B-lymphocytes in hypotonic Ringer solution, we found slightly differing regulatory volume decrease (RVD) curves for the cell lines under study. Addition of 15-60 microM GdCl3 in hypotonic Ringer increased light scattering, pointing to cell swelling beyond normal values. RVD was not observed in those experiments. A corresponding effect was seen in isotonic Ringer containing GdCl3. In either osmotic situation Gd(3+)-induced cell swelling was abolished by monoclonal mouse anti-human type-1 porin antibodies. Agonist and antibody effects were dose dependent. Finally, videocamera-monitored control experiments with adherent HeLa cells verified the direct effect of the agonist on cell swelling in hypo- or isotonic situations and its prevention by the antibodies. We conclude that GdCl3 opens plasmalemma-integrated porin channels, allowing ions to following their gradients, resulting in cell swelling. Since respiratory epithelium expresses porin channels in the apical membrane, the use of gadolinium to activate ORCC may represent a new therapeutic approach in CF.

Studies on human porin XXI: gadolinium opens Up cell membrane standing porin channels making way for the osmolytes chloride or taurine-A putative approach to activate the alternate chloride channel in cystic fibrosis.

We recently proposed that cell-membrane-integrated vertebrate porin/voltage-dependent anion-selective channel (VDAC) forms part of the outwardly rectifying chloride channel (ORCC) complex that may be involved in volume regulation. The results we present here support this thesis. According to light scattering measurements micromolar concentrations of Gd(3+) induce cell swelling of human healthy and cystic fibrosis (CF) B-lymphocyte cell lines in isotonic Ringer solution. In high-potassium Ringer solution additional swelling is observed. Gd(3+) induces excessive cell swelling of cell lines in hypotonic Ringer solutions, containing 70 mM NaCl or 135 mM taurine, respectively. The gadolinium effect is lost when NaCl is replaced by Na-gluconate. Using video camera monitoring we show that HeLa cells also swell in micromolar concentrations of Gd(3+) in isotonic taurine Ringer solution. The dose-dependent effect of the agonist was always blocked by extracellular application of anti-human type-1 porin antibodies. Together with data on a decreasing effect of micromolar amounts of gadolinium on the voltage dependence of reconstituted human porin the results prove the involvement of porin channels in the swelling behavior in different cell lines. As a mechanism we propose that ionic gadolinium opens up plasmalemma-integrated porin channels, chloride or taurine then following their concentration gradients into the cells. Furthermore, our data argue for a single pathway for inorganic and organic osmolytes during regulatory volume decrease after cell swelling. There is indirect evidence that porin forms part of the cystic fibrosis relevant ORCC channel. Gadolinium thus may work to open the alternate chloride channel in CF.

Overview and historical development of dexrazoxane.

Dexrazoxane prevents the dose-limiting cardiotoxicity of the anthracyclines without reducing their antitumor efficacy and without new adverse side effects. Dexrazoxane reduces the severity of gastrointestinal symptoms of the anthracycline containing combination doxorubicin, 5-fluorouracil, cyclophosphamide and most surprisingly and importantly, dexrazoxane increases the median survival time of advanced breast cancer responders to the doxorubicin, 5-fluorouracil, cyclophosphamide regimen. The median survival time is doubled as compared to controls to nearly 3 years.

Chemical, biological and clinical aspects of dexrazoxane and other bisdioxopiperazines.

The bisdioxopiperazine dexrazoxane (ICRF-187) has proven to be clinically very effective in reducing the cardiotoxicity of doxorubicin and other anthracyclines. Doxorubicin is thought to exert its toxicity through iron-based oxygen free radical-induced oxidative stress on the relatively unprotected cardiac muscle. Upon hydrolysis, dexrazoxane forms a compound similar to ethylenediaminetetraacetic acid (EDTA) which, like EDTA, is a strong chelator of iron. Dexrazoxane presumably exerts its cardioprotective effects by either binding free or loosely bound iron, or iron complexed to doxorubicin, thus preventing or reducing site-specific oxygen radical production that damages cellular components. The chemistry, biochemistry, and cell biology of dexrazoxane and other bisdioxopiperazines are discussed. The pre-clinical studies demonstrating the protective effects of dexrazoxane against toxicities caused by doxorubicin, other anthracyclines, bleomycin, alloxan, acetaminophen, and oxygen are also discussed. In vitro and in vivo studies of the cardioprotective and other effects of other bisdioxopiperazines are also covered. Also discussed are the anti-metastatic and radiosensitization effects of razoxane and dexrazoxane. The current clinical status of dexrazoxane in preventing anthracycline-induced toxicities in both adult and pediatric patients is reviewed.

Cardioprotection by dexrazoxane (Cardioxane; ICRF 187): progress in supportive care.

The dose-limiting toxicity of the widely used anticancer agent, doxorubicin, is a destructive, irreversible and progressive cardiomyopathy. Prevention of this cardiotoxicity without reduction of antitumour efficacy or the production of new toxicities has therefore been a long-time therapeutic goal. It has now been largely achieved by prior administration of dexrazoxane (DXRz; Cardioxane in Europe; Zinecard in North America; ICRF 187). Six randomized, controlled clinical trials in breast and lung cancer and in soft tissue sarcomas of children have shown a 90% reduction in doxorubicin-induced cardiotoxicity. The results of all these trials lead to the conclusion that DXRz permits: (1) cardiotoxic doses of doxorubicin to be given without cardiotoxicity; (2) patients with increased cardiac risk factors to be treated with full doses of dioxorubicin; (3) second-line treatment with other cardiotoxic drugs.

Studies on human porin: XIII. The type-1 VDAC 'porin 31HL' biotinylated at the plasmalemma of trypan blue excluding human B lymphocytes.

In 1989, we demonstrated for the first time the expression of the VDAC 'Porin 31HL' in the plasmalemma of human B lymphocytes, then giving first evidence of a multi-topological expression of VDAC. Meanwhile, data from this and other laboratories support our proposal of a multi-compartment distribution of the channel in mammalian tissues. Here, by biotinylation of plasmalemma-integrated proteins of proven living B lymphocytes, followed by two-dimensional electrophoresis, immuno- and streptavidin affinity blotting, we show that part of the channel molecules can be labelled at the outer membrane of the cells. Thus, by a relevant approach our results invalidate objections concerning putative cross-reactivity of anti-human Type-1 porin antibodies with non-VDAC proteins at the outer cell membrane.

High dose dexamethasone and base of brain irradiation for hormone refractory metastatic carcinoma of the prostate.

High dose dexamethasone combined with irradiation to the base of the brain achieved a dramatic beneficial effect in two terminal cases of widespread metastatic carcinoma of the prostate involving cranial nerves and the entire skeleton. Pain requiring very large doses of analgesics and anemia requiring blood transfusions every 3-4 weeks were improved rapidly. No further transfusions were needed.

Responses of liver metastases to radiotherapy and razoxane.

Twenty-five patients with liver metastases, chiefly due to colorectal cancer, were given a loading dose of razoxane for 3 days before 5 consecutive days of radiotherapy to the whole liver. Patients also took razoxane during the radiotherapy and then for one month afterwards. Liver tumour volume was measured on CT scans using the ELSCINT 3D soft tissue imaging programme just before and 4 weeks after the end of radiotherapy treatment. Twelve of the 25 patients had tumour volume reductions of more than 50%. The overall major response rate therefore is 12/25 (48%). In two of the major responders the liver metastases were due to recurrent stomach cancer. In addition to the 12 responders, four patients had a reduction of more than 20% but less than 50%, thus giving an overall response rate of 16/25 (64%). These results can form the basis of a formal, randomized, controlled clinical trial of radiotherapy alone (or any other treatment) compared with radiotherapy and razoxane in the difficult and life threatening condition presented by liver metastases.

Radiotherapeutic enhancement by razoxane.

Razoxane blocks cell division in the G2/M phase of the cell generation cycle and appears to normalize tumour neovasculature development. These were the principal reasons for the examination and probably for the demonstration of the radiosensitizing activity of Rz. Specially intriguing has been the finding that radiation of primary tumour implants in animals treated with Rz has a powerful potentiating effect on the antimetastatic activity of the combination. This concept has not yet received any clinical examination. Clinical trials with radiotherapy and Rz have demonstrated the clearest beneficial effects in terms of response rates and maintained local control in soft tissue sarcomas and possibly in recurrent rectal and in bladder carcinomas. Interesting heightened activity has also been found in hepatic metastases from gastrointestinal tumours. Carcinomas of the cervix, bronchus and head and neck, however, have not shown any benefit from the combination compared with radiotherapy alone.

Multiple differences between wild-type B16 melanoma cells and a wheat germ agglutinin resistant clone.

A low-metastatic, glycosylation-defective variant of the B16 murine melanoma was obtained by Tao and Burger (1977) through selection with wheat germ agglutinin. We found that variant and parental (wild-type) cell lines were equally invasive when confronted with precultured embryonic chick heart fragments in vitro. Also, a short-term in vivo arrest assay showed no significant differences. After intravenous injection, wild-type cells killed the recipient mice faster than did the variant cells. We were able to confirm the changes in glycosylation at the enzyme level. In addition, we showed that the pattern of endogenous lectins was strikingly different, at least at the quantitative level. We also looked at another set of receptor proteins, namely receptors for neurotransmitters coupled to adenylate cyclase. The response to the vasoactive intestinal peptide and prostaglandins was lower in the variant cells, which also had a delayed response to cholera toxin. Although most of the data can be explained by altered glycosylation in the variant cells, the large number of differences between variant and parent cells makes it difficult to identify the biochemical basis of altered metastatic behaviour. This might also be the case with other pairs of cells differing in metastatic activity.