The blood-brain barrier and oncology: new insights into function and modulation

The efficacy of chemotherapy for malignant primary or metastatic brain tumours is still poor. This is at least partly due to the presence of the blood-brain barrier (BBB). The functionality of the BBB can be explained by physicochemical features and efflux pump mechanisms. An overview of the literature is presented with emphasis on oncology. The BBB consists of capillary endothelial cells that lack fenestrations and are connected together with continuous tight junctions, with a high electrical resistance. Permeability of tight junctions can be increased in vitro by contraction of the cytoskeleton, caused by bradykinin agonists. Different efflux pumps are present in the BBB. Examples are P-glycoprotein (P-gp), organic anion transporters, (OAT) and multidrug-resistance-associated proteins (MRP)(1 and 3). These pumps act as a multi-specific efflux pump for various chemotherapeutic drugs. Experiments have shown that P-gp can be inhibited by different non-chemotherapeutic substrates such as cyclosporin A. The functionality in vivo of P-gp can be measured with positron emission tomography and [(11)C]-verapamil or with single photon emission computer tomography and(99m)Tc-sestamibi. MRP(1)and MRP(3)act as organic anion transporters that in vitro act as efflux pumps for substances that are conjugated or co-transported with glutathione and glucuronide, respectively. Methotrexate has been recently demonstrated to be transported by MRP(1)and MRP(3). Results of studies which demonstrate the clinical relevance and applicability of BBB modulators are eagerly awaited.

Long-term chemotherapy-related cardiovascular morbidity

As a consequence of the successful use of chemotherapy in the treatment of curable neoplasms such as germ cell tumours and malignant lymphomas, and the increasing application of primary and adjuvant chemotherapy for various tumour types, the number of patients with a prolonged life expectancy after treatment is rising. Attention to long-term side-effects, including cardiovascular toxicity, is therefore of growing importance. In this review we evaluate the literature on long-term cardiovascular toxicity related to chemotherapy in adult patients. Two categories of patient with favourable life expectancy have been reviewed, namely patients cured of metastatic disease by chemotherapy and patients treated with adjuvant chemotherapy. In the first category, the literature on long-term cardiovascular morbidity in survivors of metastatic testicular cancer and lymphomas is discussed, while in the second category this is done for patients treated with adjuvant chemotherapy for breast and colon cancer. As well as the direct toxic effects of chemotherapy on the cardiovascular system, the indirect toxic effects such as chemotherapy-related metabolic changes that may cause cardiovascular morbidity are also discussed.

Soft tissue leiomyosarcomas and malignant gastrointestinal stromal tumors: differences in clinical outcome and expression of multidrug resistance proteins

PURPOSE

Several studies have reported clinical behavior and chemotherapy resistance in leiomyosarcomas, but these studies did not differentiate between soft tissue leiomyosarcomas (LMS) and malignant gastrointestinal stromal tumors (GIST). Multidrug resistance (MDR) has been associated with the expression of P-glycoprotein (P-gp), multidrug resistance protein (MRP(1)), and lung resistance protein (LRP). The aim of the present study was to compare LMS and GIST with respect to clinical outcome and MDR parameters.

PATIENTS AND METHODS

Clinical outcome was evaluated in 29 patients with a primary deep-seated LMS and 26 patients with a primary malignant GIST. Paraffin-embedded material, available for 26 patients with LMS and 25 with GIST, was used for immunohistochemical detection of P-gp, MRP(1), LRP, and c-kit.

RESULTS

Mean overall survival (OS) was 72 months for LMS patients and 31 months for GIST patients (P: <.05). Metastases occurred in 16 (59%) of 27 assessable LMS patients and in 10 (56%) of 18 assessable GIST patients. LMS predominantly metastasized to the lungs (14 of 16 patients), whereas GIST tended to spread to the liver (five of 10 patients) and the abdominal cavity (three of 10 patients; P: <.001). P-gp and MRP(1) expression was more pronounced in GIST than in LMS (P: <.05): the mean percentage of P-gp expressing cells was 13.4% in patients with LMS and 38.4% in patients with GIST, and the mean percentage MRP(1) expressing cells was 13.3% in patients with LMS and 35.4% in patients with GIST. LRP expression did not differ between LMS and GIST. c-kit was expressed in 5% of the LMS patients and in 68% of the GIST patients.

CONCLUSION

LMS patients have a better survival than GIST patients, and the metastatic pattern is different. Expression of MDR proteins in LMS is less pronounced than in GIST.

A phase I study of a new polyamine biosynthesis inhibitor, SAM486A, in cancer patients with solid tumours

Because tumour cell proliferation is highly dependent upon up-regulation of de-novo polyamine synthesis, inhibition of the polyamine synthesis pathway represents a potential target for anticancer therapy. SAM486A (CGP 48664) is a new inhibitor of the polyamine biosynthetic enzyme S-adenosylmethionine decarboxylase (SAMDC), more potent and specific than the first-generation SAMDC inhibitor methylglyoxal (bis) guanylhydrazone (MGBG). Preclinical testing confirmed promising antiproliferative activity. In this phase I study, SAM486A was given 4-weekly as a 120 h infusion. 39 adult cancer patients were enrolled with advanced/refractory disease not amenable to established treatments, PS </= 2, adequate marrow, liver, renal and cardiac function. Doses were escalated in 100% increments without toxicity in 24 pts from 3 mg m(-2)cycle(-1)up to 400 mg m(-2)cycle(-1). At 550 and 700 mg m(-2)cycle(-1)reversible dose-limiting neutropenia occurred. Other toxicities included mild fatigue, nausea and vomiting. No objective remission was seen. Pharmakokinetic analysis showed a terminal half-life of approximately 2 days. AUC and Cmax were related to dose; neutropenia correlated with AUC. The recommended dose for further phase II studies on this schedule is 400 mg m(-2)cycle(-1).

Cardiovascular morbidity in long-term survivors of metastatic testicular cancer

PURPOSE

To determine whether long-term survivors of metastatic testicular cancer have an increased risk of cardiovascular morbidity more than 10 years after chemotherapy.

PATIENTS AND METHODS

Eighty-seven patients treated with cisplatin-containing chemotherapy before 1987 who were in remission for at least 10 years and whose ages were </= 50 years at the time of analysis were evaluated for the occurrence of cardiovascular events. Sixty-two of 87 patients were additionally evaluated for cardiac damage and cardiovascular risk factors. Their cardiovascular risk profile was compared with that of 40 patients with comparable age and follow-up duration treated with orchidectomy only for stage I disease.

RESULTS

Major cardiac events were found in five (6%) of the 87 patients (age at time of event, 30 to 42 years; time after chemotherapy, 9 to 16 years): two with myocardial infarction and three with angina pectoris with proven myocardial ischemia. An increased observed-to-expected ratio of 7.1 (95% confidence interval, 1.9 to 18.3) for coronary artery disease, as compared with the general male Dutch population, was found. In addition, one patient experienced a cerebrovascular accident. Exercise ECG did not reveal cases of subclinical coronary artery disease. Echocardiography showed normal systolic left ventricular function in most patients, but diastolic left ventricular function was disturbed in 33% of the patients. Of 62 chemotherapy patients, 79% had hypercholesterolemia, 39% had hypertension, 25% still experienced Raynaud's phenomenon, and 22% had microalbuminuria. Compared with patients with stage I disease, the chemotherapy patients had higher blood pressure and higher total cholesterol and triglyceride levels and were more insulin-resistant.

CONCLUSION

In long-term survivors of metastatic testicular cancer, we observed a significantly increased risk for occurrence of cardiac events accompanied by a persisting unfavorable cardiovascular risk profile. Accurate follow-up, focused on cardiovascular complications and aimed at intervention in these young cancer survivors, seems to be important.

Geographic clustering of testicular cancer incidence in the northern part of The Netherlands

Geographic variations in testicular cancer incidence may be caused by differences in environmental factors, genetic factors, or both. In the present study, geographic patterns of age-adjusted testicular cancer incidence rates (IRs) in 12 provinces in The Netherlands in the period 1989-1995 were analysed. In addition, the age-adjusted IR of testicular cancer by degree of urbanization was evaluated. Cancer incidence data were obtained from the Netherlands Cancer Registry. The overall annual age-adjusted IR of testicular cancer in The Netherlands in the period 1989-1995 was 4.4 per 100000 men. The province Groningen in the north of the country showed the highest annual IR with 5.8 per 100000 men, which was higher (P < 0.05) than the overall IR in The Netherlands (incidence rate ratio (IRR) 1.3, 95% confidence interval (CI) 1.1-1.6). The highest IR in Groningen was seen for both seminomas and non-seminomas. In addition, Groningen showed the highest age-specific IRs in all relevant younger age groups (15-29, 30-44 and 45-59 years), illustrating the consistency of data. The province Friesland, also situated in the northern part of the country, showed the second highest IR of testicular cancer with 5.3 cases per 100000 men per year (IRR 1.2, 95% CI 1.0-1.5, not significant). This mainly resulted from the high IR of seminoma in Friesland. Analysis of age-adjusted IRs of testicular cancer by degree of urbanization in The Netherlands showed no urban-rural differences at analysis of all histological types combined, or at separate analyses of seminomas and non-seminomas. Geographic clustering of testicular cancer seems to be present in the rural north of The Netherlands with some stable founder populations, which are likely to share a relatively high frequency of genes from common ancestors including genes possibly related to testicular cancer. Although this finding does not exclude the involvement of shared environmental factors in the aetiology of testicular cancer, it may also lend support to a genetic susceptibility to testicular cancer development. Testicular cancer cases in stable founder populations seem particularly suitable for searching for testicular cancer susceptibility genes because such genes are likely to be more frequent among affected men in such populations.

Effects of peripheral stem cell or bone marrow reinfusion on peripheral serotonin metabolism

Reinfusion of autologous hematopoietic peripheral blood stem cells (PBSC) or bone marrow is often accompanied by flushing, dyspnea, abdominal cramping, nausea and diarrhea. These symptoms and the observation that they can be prevented by ondansetron, a selective 5-HT3 receptor antagonist, led to the assumption that these side-effects are due to infusion of free serotonin during the reinfusion of PBSC or bone marrow. Twenty-five patients with solid tumors received, after myeloblative chemotherapy, a total of 30 reinfusions of PBSC and/or bone marrow. In 17 patients, serotonin levels in the bags containing the PBSC were measured. In all patients, platelet serotonin levels were determined before and 1 h post-reinfusion. In addition, before and 24 h after reinfusion urine was collected for determination of 5-hydroxyindole acetic acid (5-HIAA) and serotonin concentrations. Mean (+/- s.d.) total serotonin concentration in the bags was 2404 +/- 1555 nmol/l. Mean total volume reinfused was 471 +/- 185 ml. After reinfusion, the mean (+/- s.d.) levels of serotonin in platelets in patients increased from 3.2 +/- 1.4 nm/10(9) at baseline to 3.8 +/- 2.0 nm/10(9) (P = 0.02). Neither 24 h urinary 5-HIAA nor serotonin levels were affected. These results indicate that reinfusion of PBSC or bone marrow is accompanied by substantial infusion of free serotonin, which might explain the observed side-effects and justify the use of 5-HT3 receptor antagonists as pre- medication for this procedure.

Epidemiological aspects of soft tissue sarcomas (STS)--consequences for the design of clinical STS trials

The purpose of the study was to gain insight into epidemiological aspects of soft tissue sarcomas (STS), based on the population-based cancer registry of the Comprehensive Cancer Center North-Netherlands (CCCN), and to provide data for the development of future STS clinical trials. 456 primary STS (Kaposi, urogenital and gastro-intestinal STS excluded), registered from 1989 to 1995 by the cancer registration of the Comprehensive Cancer Center North-Netherlands (CCCN), were analysed. The annual, age-adjusted, STS incidence was 3.6 per 100,000. Incidence increased with age. Half of the patients were over the age of 65 years. Malignant fibrous histiocytomas and liposarcomas were most frequently encountered. At presentation, nodal involvement was rare (3-8%). Distant metastases were more frequently encountered (9-14%), and appeared to be related to tumour size and site. Above 70 years of age, 16% of patients received no treatment at all, especially for metastatic disease.

Mycobacterium ulcerans infection

After tuberculosis and leprosy, Buruli-ulcer disease (caused by infection with Mycobacterium ulcerans) is the third most common mycobacterial disease in immunocompetent people. Countries in which the disease is endemic have been identified, predominantly in areas of tropical rain forest; the emergence of Buruli-ulcer disease in West African countries over the past decade has been dramatic. Current evidence suggests that the infection is transmitted through abraded skin or mild traumatic injuries after contact with contaminated water, soil, or vegetation; there is one unconfirmed preliminary report on possible transmission by insects. The clinical picture ranges from a painless nodule to large, undermined ulcerative lesions that heal spontaneously but slowly. Most patients are children. The disease is accompanied by remarkably few systemic symptoms, but occasionally secondary infections resulting in sepsis or tetanus cause severe systemic disease and death. Extensive scarring can lead to contractures of the limbs, blindness, and other adverse sequelae, which impose a substantial health and economic burden. Treatment is still primarily surgical, and includes excision, skin grafting, or both. Although BCG has a mild but significant protective effect, new vaccine developments directed at the toxins produced by M. ulcerans are warranted. In West Africa, affected populations are underprivileged, and the economic burden imposed by Buruli-ulcer disease is daunting. Combined efforts to improve treatment, prevention, control, and research strategies (overseen by the WHO and funded by international relief agencies) are urgently needed.

Familial testicular cancer in a single-centre population

Familial occurrence of testicular cancer suggests a genetic predisposition to the disease. A genetic susceptibility may also be reflected by the occurrence of bilateral testicular neoplasms and the high rates of urogenital developmental anomalies in families prone to testicular cancer. In this study, the proportion of familial testicular cancer cases was analyzed retrospectively in a single-centre population of 693 testicular cancer patients treated between 1977 and 1997 and the relative risk (RR) for first-degree relatives of patients was estimated. In addition, the existence of bilateral testicular neoplasms and urogenital developmental anomalies in familial testicular cancer patients was evaluated. 24 of the 693 patients (3.5%) had a first-degree relative with testicular cancer. These 24 cases belonged to 17 families; in 7 of these 17 families both affected first-degree family members were part of the study population of 693 patients. Consequently, the 693 studied patients belonged to a total of 686 families. Thus, the actual proportion of familial testicular cancer was 2.5% (17 of 686 families). The familial cases consisted of 11 brother pairs, including 2 pairs of identical twins and 1 pair which also had two affected cousins, and 6 father-son pairs (in total 36 cases, 12 treated elsewhere). Estimates of the RR to first-degree relatives showed a 9- to 13-fold increased RR to brothers (P < 0.001) and a 2-fold increased RR to fathers (P = non-significant (n.s)) of testicular cancer patients. Among the 36 patients with familial testicular cancer, 2 (5.6%) had bilateral testicular cancer, 4 (11.1%) had undescended testis, 3 (8.3%) had inguinal hernia, and 1 (2.8%) showed renal hypoplasia. The present data on familial occurrence of testicular cancer may lend support to a role of genetic factors in the aetiology of testicular cancer.

An unusual presentation of sepsis caused by coagulase-negative staphylococci

We describe a 25-year-old male presenting with fever during the non-neutropenic phase of chemotherapy. The presentation was that of a viral infection. The cause of the fever turned out to be a bacteremia with coagulase-negative staphylococci (CONS) originating from a totally implanted venous access port (VAP). We briefly discuss the different types of VAP-related infections and treatment modalities.

Detection of anthracycline-induced cardiotoxicity

The use of anthracyclines, a group of potent anti-cancer agents incorporated into the treatment of a wide variety of solid and haematological tumours, is limited by its cardiotoxicity that can result in congestive heart failure (CHF). The best method to detect cardiotoxicity at an early stage in order to prevent severe deterioration, is still an unsolved problem. Although endomyocardial biopsy is considered to be the most sensitive and specific test for this purpose, its use is limited by its invasiveness. In daily practice, oncologists make use of parameters of systolic function (left ventricular ejection fraction, or fractional shortening) to detect cardiotoxicity, but these methods are not able to identify cardiotoxicity at an early stage. Based on increasing knowledge into the pathophysiology of anthracycline-induced cardiotoxicity and heart failure in general, new methods including the determination of diastolic function parameters, anti-myosin scintigraphy, assessment of heart rate variability, and the determination of biochemical markers have been proposed to identify patients at risk of the development of CHF in an early stage. However, most of these newer methods have not yet been adequately evaluated to allow them to be recommended for use in routine clinical practice.

Phase I study of transforming growth factor-beta3 mouthwashes for prevention of chemotherapy-induced mucositis

The purpose of this study was to establish the safety and tolerability of recombinant transforming growth factor-beta3 (TGF-beta3; CGP 46614) mouthwashes intended for prevention of chemotherapy-induced mucositis. Local effects were especially analyzed by objective and subjective measurements of mucositis. Secondary aims were analysis of potential systemic exposure and development of anti-TGF-beta3-antibodies. Eleven breast cancer patients received chemotherapy with 1.5 g/m2 cyclophosphamide i.v., 80 mg/m2 epirubicin i.v., and 1.0 g/m2 5-fluorouracil i.v. (n = 8) or 1.6 g/m2 carboplatin i.v., 480 mg/m2 thiotepa i.v., and 6 g/m2 cyclophosphamide i.v. divided over 4 days (n = 3). TGF-beta3 mouthwashes (10 ml; provided by Novartis, Basel, Switzerland) were administered for 4 days, four times a day, starting 1 day before chemotherapy. The dose was escalated in following patients from 25 microg/ml (n = 3) to 50 microg/ml (n = 3) and 100 microg/ml (n = 5). Clinically, the mucosa was scored objectively and according to WHO criteria. The percentage of viable oral epithelial cells was determined by trypan blue dye exclusion. Morphology of cells was assessed in buccal smears. Plasma samples were collected for determination of TGF-beta3 levels and anti-TGF-beta3-antibodies. Adverse events were recorded by the patient in a diary. Mouthwashes with TGF-beta3 were well tolerated. Three patients scored for mucositis > grade 0 (WHO grading criteria). The percentage of viable oral epithelial cells in patients treated with 1.5 g/m2 cyclophosphamide i.v., 80 mg/m2 epirubicin i.v., and 1.0 g/m2 5-fluorouracil i.v. was stable, whereas in patients treated with 1.6 g/m2 carboplatin i.v., 480 mg/m2 thiotepa i.v., and 6 g/m2 cyclophosphamide i.v. divided over 4 days, an increase was observed. The morphology of buccal cells showed a transient shift from mature to immature cells in the first week. Neither systemic absorption of TGF-beta3 nor development of TGF-beta3-antibodies was observed. TGF-beta3 mouthwashes were well tolerated and deserve further study in preventing chemotherapy-induced mucositis.

A new in vivo method to study P-glycoprotein transport in tumors and the blood-brain barrier

Drug resistance is a major cause of chemotherapy failure in cancer treatment. One reason is the overexpression of the drug efflux pump P-glycoprotein (P-gp), involved in multidrug resistance (MDR). In vivo pharmacokinetic analysis of P-gp transport might identify the capacity of modulation by P-gp substrate modulators, such as cyclosporin A. Therefore, P-gp function was measured in vivo with positron emission tomography (PET) and [11C]verapamil as radiolabeled P-gp substrate. Studies were performed in rats bearing tumors bilaterally, a P-gp-negative small cell lung carcinoma (GLC4) and its P-gp-overexpressing subline (GLC4/P-gp). For validation, in vitro and biodistribution studies with [11C]daunorubicin and [11C]verapamil were performed. [11C]Daunorubicin and [11C]verapamil accumulation were higher in GLC4 than in GLC4/P-gp cells. These levels were increased after modulation with cyclosporin A in GLC4/P-gp. Biodistribution studies showed 159% and 185% higher levels of [11C]daunorubicin and [11C]verapamil, respectively, in GLC4 than in GLC4/P-gp tumors. After cyclosporin A, [11C]daunorubicin and [11C]verapamil content in the GLC4/P-gp tumor was raised to the level of GLC4 tumors. PET measurements demonstrated a lower [11C]verapamil content in GLC4/P-gp tumors compared with GLC4 tumors. Pretreatment with cyclosporin A increased [11C]verapamil levels in GLC4/P-gp tumors (184%) and in brains (1280%). This pharmacokinetic effect was clearly visualized with PET. These results show the feasibility of in vivo P-gp function measurement under basal conditions and after modulation in solid tumors and in the brain. Therefore, PET and radiolabeled P-gp substrates may be useful as a clinical tool to select patients who might benefit from the addition of a P-gp modulator to MDR drugs.

99mTc-Sestamibi scanning with SDZ PSC 833 as a functional detection method for resistance modulation in patients with solid tumours

BACKGROUND

Our aim was to determine the value of 99mTc-Sestamibi scanning as functional detection method of P-glycoprotein (Pgp) blockade by PSC 833 in solid tumour patients.

PATIENTS AND METHODS

Day 1 and day 4 after 2,200 mg orally administered PSC 833 the tumour area was scanned after intravenous (i.v.) administration of 400 MBq 99mTc-Sestamibi. In tumours with net 99mTc-Sestamibi uptake and in the hepatic region K-efflux was determined. Whole blood was analyzed for 99mTc-Sestamibi, and PSC 833 levels.

RESULTS

Fourteen patients were included. In the only Pgp-positive tumour with positive 99mTc-Sestamibi scanning K-efflux of 99mTc-Sestamibi decreased significantly after PSC 833 intake. A net inhibition of liver efflux of Sestamibi after PSC 833 intake was observed in all evaluable patients. PSC 833 blood levels were all above 2 mg/L during scanning; 99mTc-Sestamibi blood levels post versus pre PSC 833 were unchanged.

CONCLUSIONS

PSC 833 induced modulation of K-efflux of 99mTc-Sestamibi in a Pgp positive tumour and in all patients in the liver.

Prevention of febrile leucopenia after chemotherapy in high-risk breast cancer patients: no significant difference between granulocyte-colony stimulating growth factor or ciprofloxacin plus amphotericin B

In a prospective randomized trial, 40 stage IV breast cancer patients undergoing intermediate high-dose chemotherapy (cyclophosphamide, 5-fluorouracil plus epirubicin or methotrexate), received either recombinant human G-CSF (rhG-CSF, group I) or ciprofloxacin and amphotericin B (CAB, group II) for prevention of febrile leucopenia (FL). In group I, seven of 18 patients developed FL (after 10/108 courses); in group II, seven of 22 patients (7/98 courses) (P = NS). Median hospitalization duration and costs were not different. RhG-CSF was 6.6 times more expensive per course than CAB. In conclusion, prophylactic CAB has similar efficacy to rhG-CSF in this setting, and is more cost-effective.

Decision-making process in patients before entering phase III cancer clinical trials: a pilot study

The present study was performed to gain insight into the decision-making process that patients go through when asked to participate in a cancer clinical trial. Fourteen cancer patients entered a pilot study concerning decision making. They were interviewed in a semistructured manner after consenting or refusing to participate in a randomized phase III clinical trial concerning chemotherapy or immunotherapy. Results from this study showed that patients, after receiving information from the medical oncologist, oncology nurse, or both, decide about participation instantaneously. This means that time for procedural soundness has not been used, which raises questions about the normative quality of the decision.

Visualization of multidrug resistance in vivo

Various mechanisms are involved in multidrug resistance (MDR) for chemotherapeutic drugs, such as the drug efflux pumps, P-glycoprotein (Pgp) and multidrug resistance-associated protein (MRP). In this review the mechanisms involved in MDR are described and results are reviewed with particular attention to the in vivo imaging of Pgp and MRP. Various detection assays provide information about the presence of drug efflux pumps at the mRNA and protein levels. However, these methods do not yield information about the dynamic function of Pgp and MRP in vivo. For the study of Pgp- and MRP-mediated transport, single-photon emission tomography (SPET) and positron emission tomography (PET) are available. Technetium-99m sestamibi is a substrate for Pgp and MRP, and has been used in clinical studies for tumour imaging, and to visualize blockade of Pgp-mediated transport after modulation of the Pgp pump. Other 99mTc radiopharmaceuticals, such as 99mTc-tetrofosmin and several 99Tc-Q complexes, are also substrates for Pgp, but to date only results from in vitro and animal studies are available for these compounds. Several agents, including [11C]colchicine, [11C]verapamil and [11C]daunorubicin, have been evaluated for the quantification of Pgp-mediated transport with PET in vivo. The results suggest that radiolabelled colchicine, verapamil and daunorubicin are feasible substrates with which to image Pgp function in tumours. Uptake of [11C]colchicine and [11C]verapamil is relatively high in the chest area, reducing the value of both tracers for monitoring Pgp-mediated drug transport in tumours located in this region. In addition, it has to be borne in mind that only comparison of Pgp-mediated transport of radioalabelled substrates in the absence and in the presence of Pgp blockade gives quantitative information on Pgp-mediated pharmacokinetics. Leukotrienes are specific substrates for MRP. Therefore, N-[11C]acetyl-leukotriene E4 provides an opportunity to study MRP function non-invasively. Results obtained in MRP2 mutated GY/TR rats have demonstrated visualization of MRP-mediated transport. This tracer permits the study of MRP transport function abnormalities in vivo, e.g. in Dubin-Johnson patients, who are MRP2 gene deficient. Results obtained show the feasibility of using SPET and PET to study the functionality of MDR transporters in vivo.

[Buruli ulcer (Mycobacterium ulcerans infection); report from the International Congress in Yamoussoukro, Ivory Coast]

Mycobacterium ulcerans infection (Buruli ulcer) is the third important mycobacterial disease world-wide in immunocompetent humans, after tuberculosis and leprosy. M. ulcerans is an environmental mycobacterium which has now been recovered from water and soil in swampy areas, and transmission to man occurs presumably through minor skin traumas. Endemic foci are known throughout the world, predominantly in tropical rain forest areas. The clinical presentation varies between a papule, a nodule or an ulceration with typically undermined edges. Surgery is the only effective treatment. BCG vaccination has a moderate protective effect. An association with HIV infection has not been demonstrated so far. Poor communities, with limited access to health care, and especially children are affected. The medical and socioeconomic burden imposed by the disease is tremendous. During the last decade the incidence of the disease has increased dramatically, particularly in West Africa. Possibly this is connected with changes in the natural ecosystem. The Yamoussoukro declaration on Buruli ulcer, adopted July 6, 1998, is the basis of improvement of awareness, health education, treatment, and research on M. ulcerans infection. Support by the international community is urgently needed.

Phase I and pharmacokinetic study of the topoisomerase II catalytic inhibitor fostriecin

We conducted a phase I and pharmacokinetic study of the topoisomerase II catalytic inhibitor fostriecin. Fostriecin was administered intravenously over 60 min on days 1-5 at 4-week intervals. Dose was escalated from 2 mg m(-2) day(-1) to 20 mg m(-2) day(-1) in 20 patients. Drug pharmacokinetics was analysed with high performance liquid chromatography with UV-detection. Plasma collected during drug administration was tested in vitro for growth inhibition of a teniposide-resistant small-cell lung cancer (SCLC) cell line. The predominant toxicities were elevated liver transaminases (maximum common toxicity criteria (CTC) grade 4) and serum creatinine (maximum CTC grade 2). These showed only a limited increase with increasing doses, often recovered during drug administration and were fully reversible. Duration of elevated alanine-amino transferase (ALT) was dose-limiting in one patient at 20 mg m(-2). Other frequent toxicities were grade 1-2 nausea/vomiting, fever and mild fatigue. Mean fostriecin plasma half-life was 0.36 h (initial; 95% CI, 0-0.76 h) and 1.51 h (terminal; 95% CI, 0.41-2.61 h). A metabolite, most probably dephosphorylated fostriecin, was detected in plasma and urine. No tumour responses were observed, but the plasma concentrations reached in the patients were insufficient to induce significant growth inhibition in vitro. The maximum tolerated dose (MTD) has not been reached, because drug supply was stopped at the 20 mg m(-2) dose level. However, further escalation seems possible and is warranted to achieve potentially effective drug levels. Fostriecin has a short plasma half-life and longer duration of infusion should be considered.