Summary Topoisomerase inhibitors constitute a new class of anti-cancer agents. Recently, topotecan and irinotecan were registered for clinical use in ovarian cancer and colorectal cancer respectively. Cytotoxicity of topoisomerase inhibitors is S-phase specific, and in vitro and in vivo studies have suggested that, for efficacy, prolonged exposure might be more important than short-term exposure to high concentration. Clinical development of those topoisomerase inhibitors that have reached this stage is also focused on schedules aiming to achieve prolonged exposure. In this review, we summarize all published preclinical studies on this topic for topoisomerase inhibitors in clinical development, namely 20-S-camptothecin, 9-nitro-camptothecin, 9-amino-camptothecin, topotecan, irinotecan and G1147211. In addition, preliminary data on clinical studies concerning this topic are also reviewed. The data suggest that prolonged exposure may indeed be relevant for anti-tumour activity. However, the optimal schedule is yet to be determined. Finally, clinical data are yet too immature to draw definitive conclusions.

The DLT in this phase I study for chronic oral topotecan for 21 days was diarrhea. The recommended dose for phase II studies is 0.5 mg/m2 twice daily.

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Topotecan administered as a 21-day continuous infusion exerts minor activity as single-agent therapy in patients with metastatic colorectal cancer.

Topoisomerase I inhibitors are interesting anti-cancer agents with a novel mechanism of action. We performed a phase I study with intravenous GI147211, a new semisynthetic camptothecin analogue, using a daily x 5 schedule administered every 3 weeks, to evaluate the side-effects and pharmacokinetics of the agent. Patients with a histologically confirmed diagnosis of a solid tumour refractory to standard froms of therapy were eligible for the study. GI147211 was given as a 30 min intravenous infusion daily for 5 consecutive days, repeated every 3 weeks. In subsequent patient cohorts the dose was escalated from 0.3 to 1.5 mg m-2 day-1. Pharmacokinetics analysis was performed on days 1 and 4 of the first course using a validated high-performance liquid chromatographic assay and non-compartmental methods. A total of 19 patients were entered into the study, one patient was not evaluable for toxicity because only one drug administration was given. Eighteen patients received a total of 67 courses through four dose levels. The dose-limiting toxicities were neutropenia and thrombocytopenia at the dose of 1.5 mg m-2 day-1. Nadirs occurred on day 15 and day 15 respectively. Other toxicities were mild and infrequent and included nausea/vomiting, headache and alopecia. The maximal tolerated dose was 1.2 mg m-2 day-1. One partial response was observed in a patient with colorectal cancer. The total plasma clearance was 999+/-184 ml min-1 (range 640-1329). The volume of distribution was 190+/-461 m-2 and the terminal half-life was 3.7+/-1.2 h. The AUC increased linearly with the administered dose. A steep and significant sigmoid relationship was established between the AUC and the percent decrease of ANC. GI147211 is a new topoisomerase I inhibitor that induced dose-limiting neutropenia and thrombocytopenia in this phase I study. The recommended dose for phase II studies with this schedule is 1.2 mg m-2 x 5 every 3 weeks.

We present a 39-year-old male patient with Down syndrome who was evaluated for fatigue, palpitations and bouts of cyanosis. Physical examination showed features of trisomy-21(Down syndrome), with a slow pulse rate, distant cardiac sounds and absent apex beat. He had normal jugular venous pressure without pulsus paradoxus. The ECG showed QRS microvoltage and flattened P and T segments. The 48-hour ambulatory ECG depicted normal sinus rhythm with intermittent short PR interval without tachyarrhythmias. The chest Xray revealed cardiomegaly without pulmonary venous congestion. Although serial transthoracic echocardiographic examination demonstrated pericardial effusion with features of tamponade, there were no overt signs of clinical cardiac tamponade. Biochemically, the serum thyroxine of 3 pmol/l (normal 10 to 25) and thyroid-stimulating hormone of 160 mU/l (normal 0.20 to 4.20)) were compatible with hypothyroidism. The patient was treated with L-thyroxine sodium daily, which was gradually increased to 0.125 mg daily. Within a few months he lost weight and became more alert; furthermore, the symptoms of hypothyroidism and the pericardial effusion resolved. It can be concluded that Down syndrome may be associated with hypothyroidism and pericardial effusion. These were alleviated following hormone replacement. Regular evaluation of thyroid function tests is important in Down syndrome. (Neth Heart J 2007;15:67-70.).

The choice of treatment of malignant lymphoma may vary considerably and is mainly determined by the pathology and clinical stage. Ultrasonography is currently one of the most sensitive techniques for evaluation of the cervical area. We set out to assess the value of ultrasound imaging when added to conventional staging (physical examination, laryngoscopy, computer tomography of thorax and abdomen, bone marrow cytology and histology) of malignant lymphoma in 47 patients with untreated lymphoma. Hodgkin's disease was present in 14 patients and non-Hodgkin's lymphoma in 33 individuals. The ultrasound results were independently compared with physical examination of the neck. Ultrasonography revealed additional pathological lymph nodes in 6/47 cases (13%). Furthermore, the diagnosis non-Hodgkin's lymphoma could be established in one patient merely as a result of ultrasonography. Ultrasonography of the neck may reveal more pathological lymph nodes in a significant number of patients and may be of value in the initial staging of patients with malignant lymphoma.