Showing papers on "Topotecan published in 2004"

Anticancer Chemosensitization and Radiosensitization by the Novel Poly(ADP-ribose) Polymerase-1 Inhibitor AG14361

Abstract: Background: Poly(ADP-ribose) polymerase-1 (PARP-1) facilitates the repair of DNA strand breaks. Inhibiting PARP-1 increases the cytotoxicity of DNA-damaging chemotherapy and radiation therapy in vitro. Because classical PARP-1 inhibitors have limited clinical utility, we investigated whether AG14361, a novel potent PARP-1 inhibitor (inhibition constant <5 nM), enhances the effects of chemotherapy and radiation therapy in human cancer cell cultures and xenografts. Methods: The effect of AG14361 on the antitumor activity of the DNA alkylating agent temozolomide, topoisomerase I poisons topotecan or irinotecan, or x-irradiation or gamma-radiation was investigated in human cancer cell lines A549, LoVo, and SW620 by proliferation and survival assays and in xenografts in mice by tumor volume determination. The specificity of AG14361 for PARP-1 was investigated by microarray analysis and by antiproliferation and acute toxicity assays in PARP-1(-/-) and PARP-1(+/+) cells and mice. After intraperitoneal administration, the concentration of AG14361 was determined in mouse plasma and tissues, and its effect on PARP-1 activity was determined in tumor homogenates. All statistical tests were two-sided. Results: AG14361 at 0.4 muM did not affect cancer cell gene expression or growth, but it did increase the antiproliferative activity of temozolomide (e.g., in LoVo cells by 5.5-fold, 95% confidence interval [CI] = 4.9-fold to 5.9-fold; P = .004) and topotecan (e.g., in LoVo cells by 1.6-fold, 95% CI = 1.3-fold to 1.9-fold; P = .002) and inhibited recovery from potentially lethal gamma-radiation damage in LoVo cells by 73% (95% CI = 48% to 98%). In vivo, nontoxic doses of AG14361 increased the delay of LoVo xenograft growth induced by irinotecan, x-irradiation, or temozolomide by two- to threefold. The combination of AG14361 and temozolomide caused complete regression of SW620 xenograft tumors. AG14361 was retained in xenografts in which PARP-1 activity was inhibited by more than 75% for at least 4 hours. Conclusion: AG14361 is, to our knowledge, the first high-potency PARP-1 inhibitor with the specificity and in vivo activity to enhance chemotherapy and radiation therapy of human cancer.

Mrp4 confers resistance to topotecan and protects the brain from chemotherapy.

Abstract: The role of the multidrug resistance protein MRP4/ABCC4 in vivo remains undefined. To explore this role, we generated Mrp4-deficient mice. Unexpectedly, these mice showed enhanced accumulation of the anticancer agent topotecan in brain tissue and cerebrospinal fluid (CSF). Further studies demonstrated that topotecan was an Mrp4 substrate and that cells overexpressing Mrp4 were resistant to its cytotoxic effects. We then used new antibodies to discover that Mrp4 is unique among the anionic ATP-dependent transporters in its dual localization at the basolateral membrane of the choroid plexus epithelium and in the apical membrane of the endothelial cells of the brain capillaries. Microdialysis sampling of ventricular CSF demonstrated that localization of Mrp4 at the choroid epithelium is integral to its function in limiting drug penetration into the CSF. The topotecan resistance of cells overexpressing Mrp4 and the polarized expression of Mrp4 in the choroid plexus and brain capillary endothelial cells indicate that Mrp4 has a dual role in protecting the brain from cytotoxins and suggest that the therapeutic efficacy of central nervous system-directed drugs that are Mrp4 substrates may be improved by developing Mrp4 inhibitors.

Imatinib mesylate is a potent inhibitor of the ABCG2 (BCRP) transporter and reverses resistance to topotecan and SN-38 in vitro.

Abstract: Imatinib mesylate (Gleevec, STI571) is a kinase inhibitor selective for Bcr-Abl, activated c-Kit kinases, and platelet-derived growth factor receptor tyrosine kinase. Imatinib mesylate, similar to many other tyrosine kinase inhibitors (TKIs), such as members of the 4-anilinoquinazoline class, competes for ATP binding. Previously, 4-anilinoquinazoline TKIs have been shown to inhibit the function of the breast cancer resistance-associated drug transporter (ABCG2), reversing resistance to camptothecin derivatives topotecan and SN-38. However, the potential to inhibit ABCG2 for the 2-phenylamino-pyrimidine class of TKIs, exemplified by imatinib mesylate, has not been examined. Here, we show that imatinib mesylate potently reverses ABCG2-mediated resistance to topotecan and SN-38 and significantly increases accumulation of topotecan only in cells expressing functional ABCG2. However, overexpression of ABCG2 does not confer resistance to imatinib mesylate. Furthermore, accumulation and efflux of [ 14 C]imatinib mesylate are unaltered between ABCG2-expressing and non-ABCG2-expressing cells or by ATP depletion. These results suggest that imatinib mesylate inhibits the function of ABCG2 but is not a substrate for this transporter.

Recurrent ovarian cancer: how important is it to treat to disease progression?

Abstract: Ovarian cancer is increasingly recognized as a chronic disease whose treatment is often characterized by administration of multiple, sequential active agents, each of which may or may not be accompanied by a tumor response. Despite the large proportion of patients who relapse and undergo longer-term treatment, the question of optimal treatment duration has not been fully addressed to date. For patients who progress on therapy, the answer is straightforward: they are switched to another active agent, presumably having a different mechanism of action from previous therapies with, ideally, limited overlapping toxicities. However, for patients who remain in partial response or who have stable disease, the answer is less apparent and less clear. The majority of oncologists believe that treatment beyond 6 cycles of a given therapy does not provide any additional benefit to patients. There are some data to support that treatment strategy. However, with the advent of new, less toxic agents, treatment to progression should be further explored. Agents that are potentially well suited for extended treatment intervals may include such properties as absence of cumulative toxicity, non-cross-resistance, positive benefit on quality of life, and convenient schedule. A number of active agents in ovarian cancer (platinum, paclitaxel, topotecan, liposomal doxorubicin, docetaxel, gemcitabine, and etoposide) will be reviewed in the context of what is known about cumulative toxicity, potential adverse effects on patients' quality of life, and evidence addressing the potential benefits of longer-term treatment.

Schedule-dependent Inhibition of Hypoxia-inducible Factor-1α Protein Accumulation, Angiogenesis, and Tumor Growth by Topotecan in U251-HRE Glioblastoma Xenografts

Abstract: We have previously shown that topotecan, a topoisomerase I poison, inhibits hypoxia-inducible factor (HIF)-1alpha protein accumulation by a DNA damage-independent mechanism. Here, we report that daily administration of topotecan inhibits HIF-1alpha protein expression in U251-HRE glioblastoma xenografts. Concomitant with HIF-1alpha inhibition, topotecan caused a significant tumor growth inhibition associated with a marked decrease of angiogenesis and expression of HIF-1 target genes in tumor tissue. These results provide a compelling rationale for testing topotecan in clinical trials to target HIF-1 in cancer patients.

Topotecan Compared With No Therapy After Response to Surgery and Carboplatin/Paclitaxel in Patients With Ovarian Cancer: Multicenter Italian Trials in Ovarian Cancer (MITO-1) Randomized Study

Abstract: Purpose Topotecan is an active second-line treatment for advanced ovarian cancer. Its efficacy as consolidation treatment after first-line standard chemotherapy is unknown. Patients and Methods To investigate whether topotecan (1.5 mg/m2 on days 1 through 5, four cycles, every 3 weeks) prolonged progression-free survival (PFS) for patients responding to standard carboplatin (area under the curve 5) and paclitaxel (175 mg/m2 administered as a 3-hour infusion in six cycles; CP), a multicenter phase III study was performed with an 80% power to detect a 50% prolongation of median PFS. Patients were registered at diagnosis and randomized after the end of CP. Results Two hundred seventy-three patients were randomly assigned (topotecan, n = 137; observation, n = 136), with a median age of 56 years. Stage at diagnosis was advanced in three fourths of patients (stage III in 65% of patients; stage IV in 10%); after primary surgery, 46% had no residual disease and 20% were optimally debulked. After CP, 87% reached a...

Reversal of breast cancer resistance protein (BCRP/ABCG2)‐mediated drug resistance by novobiocin, a coumermycin antibiotic

Abstract: Breast cancer resistance protein (BCRP/ABCG2) of an ATP-binding cassette half-transporter confers resistance against mitoxantrone and camptothecin derivatives of topotecan and irinotecan Novobiocin, a coumermycin antibiotic, is known to enhance anticancer drug sensitivity of cancer cells in vitro and in vivo, the mechanism of which remains undetermined Here we focused on drug efflux pump and examined whether novobiocin reversed drug resistance in multidrug-resistant cells highly expressing BCRP To explore the reversal mechanisms, intracellular drug accumulation was measured by flow cytometry, and a topotecan transport study using plasma membrane vesicles was performed We used PC-6/SN2-5H2 small cell lung cancer and MCF-7/MX breast cancer cells selected with SN-38 of the active irinotecan metabolite and mitoxantrone, respectively, and the BCRP cDNA transfectant MCF-7/clone 8 cells These cells expressed high levels of BCRP mRNA but not other known transporters Compared to the parental PC-6 cells, PC-6/SN2-5H2 cells were 141-, 173- and 572-fold resistant to topotecan, SN-38 and mitoxantrone, respectively Novobiocin at 60 microM decreased the degree of the above resistance by approximately 26-fold in PC-6/SN2-5H2 cells, and similarly reversed resistance in MCF-7/MX, MCF-7/clone 8 and un-selected NCI-H460 cells highly expressing BCRP Furthermore, novobiocin increased the intracellular topotecan accumulation in these cells and inhibited the topotecan transport into the membrane vesicles of PC-6/SN2-5H2 cells No effects of novobiocin in these assay were observed in the parental PC-6 and MCF-7 cells The kinetic parameters in the transport study indicated that novobiocin was a inhibitor for BCRP, resulting in competitive inhibition of BCRP-mediated topotecan transport These findings suggest that novobiocin effectively overcomes BCRP-mediated drug resistance at acceptable concentrations

The role of topotecan in the treatment of brain metastases.

Abstract: Despite advances in the treatment of systemic malignancies, the prognosis for patients with brain metastases continues to be dismal. Because the majority of cytotoxic agents seem to be unable to penetrate the blood-brain barrier, the role of chemotherapy in the treatment of brain metastases remains controversial. However, growing amounts of both laboratory and clinical data suggest that a few of the newly developed cytotoxic agents can cross the blood-brain barrier and may have a role in the treatment of patients with brain metastases. Topotecan, a novel topoisomerase I inhibitor, freely crosses the blood-brain barrier and may be clinically effective in both the therapeutic and prophylactic settings in patients with brain metastases. Recent studies have demonstrated the antitumor activity of topotecan against brain metastases, with objective response rates ranging from 33%-63% in patients with various solid tumors. The antitumor response in the central nervous system was often greater and occurred more quickly than the systemic antitumor response to topotecan treatment. This result may be explained by the lack of exposure of brain metastases to previous cytotoxic agents, suggesting a role for topotecan in patients with brain metastases. Early studies have also suggested that topotecan, an apparent radiosensitizer, may be particularly effective in combination with radiotherapy, the current standard of care for patients with brain metastases. In addition, preliminary data suggest that topotecan in combination with temozolomide (another cytotoxic agent that can cross the blood-brain barrier) may have synergistic antitumor activity against brain metastases. This review summarizes the available preclinical and clinical evidence for the role of topotecan in the treatment of brain metastases and concludes with three case studies.

Should CA-125 Response Criteria Be Preferred to Response Evaluation Criteria in Solid Tumors (RECIST) for Prognostication During Second-Line Chemotherapy of Ovarian Carcinoma?

Abstract: Purpose The aim of the study was to compare the prognostic value of a response by the Gynecologic Cancer Intergroup (GCIG) Cancer Antigen (CA) -125 response criteria and the Response Evaluation Criteria in Solid Tumors (RECIST) on survival in patients with ovarian carcinoma receiving second-line chemotherapy. Patients and Methods From a single-institution registry of 527 consecutive patients with primary ovarian carcinoma, 131 records satisfied the inclusion criteria: ovarian carcinoma of International Federation of Gynecology and Obstetrics stage IC to IV, first-line chemotherapy with paclitaxel and a platinum compound, refractory or recurrent disease, and second-line chemotherapy consisting of topotecan or paclitaxel plus carboplatin. Univariate and multivariate analyses of survival were performed using the landmark method. Results In patients with measurable disease by RECIST and with assessable disease by the CA-125 criteria (n = 68), the CA-125 criteria were 2.6 times better than the RECIST at disclo...

Efficacy of Topotecan and Cyclophosphamide Given in a Phase II Window Trial in Children With Newly Diagnosed Metastatic Rhabdomyosarcoma: A Children’s Oncology Group Study

Abstract: Purpose To determine the antitumor activity and toxicity of topotecan given immediately after cyclophosphamide as window therapy, then in combination with conventional agents in pediatric patients with newly diagnosed metastatic rhabdomyosarcoma (RMS). Patients and Methods Sixty-one patients younger than 21 years with newly diagnosed metastatic RMS or undifferentiated sarcoma were assigned window therapy (weeks 0 to 6) with topotecan (0.75 mg/m2 daily × 5 every 21 days) immediately after cyclophosphamide (250 mg/m2 daily × 5 every 21 days; TC). We continued to give these agents in combination with vincristine (VTC) to patients who showed objective improvement, partial response (PR), or complete response (CR) to TC and alternated courses of VTC with vincristine, dactinomycin and cyclophosphamide (VAC) during weeks 6 to 41 (VTC/VAC). Those who showed no response or progressive disease after TC received only VAC. All patients received radiotherapy to sites of unresected disease (weeks 15 to 21). Results The ...

Inhibitory effect of genistein and daidzein on ovarian cancer cell growth.

Abstract: Background: Survival from ovarian cancer has not changed significantly in the past twenty years requiring development of additional treatment protocols. We studied the effect of genistein and daidzein on ovarian cancer cell growth. Materials and Methods: Five ovarian cancer cell lines from Stage IIIC disease were evaluated. Sulforhodamine B and colony formation assays were used to analyze growth inhibitory effects of genistein and daidzein alone and with cisplatin, paclitaxel or topotecan. Apoptosis induction was studied by determining caspase-3 activity. Results: Inhibition of growth (50-80%), colony formation and colony size was seen at 144 Im of genistein, 0-23% reduction was demonstrated at 9 Im. At 144 Im, the colony size was inhibited >75%; at 9 Im 4/5 cell lines had >50% reduction. Caspase-3 activity was induced (0.10 to 0.56 pmol/min/Ig protein) with all concentrations of genistein. Cisplatin (2-50 Ig/ml) and topotecan (0.5-50.0 Im) combined with genistein resulted in a mostly additive effect, paclitaxel (8-200 nM) was slightly less than additive. Conclusion: We demonstrate an inhibitory effect of genistein on ovarian cancer cell growth. Despite dedicated research and increased understanding of the molecular defects associated with ovarian cancer, survival after diagnosis has changed little. Ovarian cancer remains the most dreaded of the female genital tract cancers, without much to offer currently for early diagnosis or prevention. Recently, interest in specific foods for cancer chemoprevention has increased including retinoic acid, curcumin and the isoflavanoids (genistein, daidzein and biochanin A). The effects of these agents have been studied to various degrees in many different cancers, but their role in the prevention or treatment of female genital tract cancers has not been extensively reported. Genistein, a soy isoflavanoid, has been intensely studied in relation to breast cancer. Interest first arose upon discovery of the vast difference in breast cancer rates in Asia versus Western countries (1). Large dietary differences exist, especially in genistein consumption, as the average Asian intake is 20-80 mg/day whereas the average US intake is only 1-3 mg (2,3) The dietary and disease discrepancy prompted further study into the chemopreventive and potentially therapeutic properties of genistein. Genistein has been found to inhibit cell proliferation,

Results of a phase II upfront window of pharmacokinetically guided topotecan in high-risk medulloblastoma and supratentorial primitive neuroectodermal tumor

Abstract: Purpose To assess the antitumor efficacy of pharmacokinetically guided topotecan dosing in previously untreated patients with medulloblastoma and supratentorial primitive neuroectodermal tumors, and to evaluate plasma and CSF disposition of topotecan in these patients. Patients and Methods After maximal surgical resection, 44 children with previously untreated high-risk medulloblastoma were enrolled, of which 36 were assessable for response. The topotecan window consisted of two cycles, administered initially as a 30-minute infusion daily for 5 days, lasting 6 weeks. Pharmacokinetic studies were conducted on day 1 to attain a topotecan lactone area under the plasma concentration-time curve (AUC) of 120 to 160 ng/mL·h. After 10 patients were enrolled, the infusion was modified to 4 hours, with dosage individualization. Results Of 36 assessable patients, four patients (11.1%) had a complete response and six (16.6%) showed a partial response, and disease was stable in 17 patients (47.2%). Toxicity was mostly...

Response to paclitaxel, topotecan, and topotecan-cyclophosphamide in children with untreated disseminated neuroblastoma treated in an upfront phase II investigational window: A Pediatric Oncology group study

Abstract: Purpose Most children older than 1 year of age with metastatic neuroblastoma (NB) die despite intensive chemotherapy and bone marrow transplantation. The Pediatric Oncology Group conducted a study of paclitaxel, topotecan, and topotecan-cyclophosphamide (topo-cyclo) in newly diagnosed children with stage IV NB. Patients and Methods There were 102 patients enrolled between September 1993 and October 1995; two of them were later shown to be ineligible. Of the remaining 100 patients, the first cohort of 33 patients received paclitaxel 350 mg/m2 intravenously (IV) over 24 hours every 14 to 21 days; the next 33 patients received topotecan 2 mg/m2/d for 5 days IV every 21 days; a third cohort of 34 patients were treated with IV cyclophosphamide 250 mg/m2 followed by topotecan 0.75 mg/m2 each day for 5 days every 21 days. Patients were re-evaluated after two courses and then treated with intensive induction therapy and bone marrow transplantation. Results Objective responses (complete response + partial response...

Topotecan in the Treatment of Recurrent Small Cell Lung Cancer: An Update

Abstract: Small cell lung cancer (SCLC) is an aggressive malignancy with a high propensity for early regional and distant metastasis. Response rates to first-line chemotherapy are typically high, but short lived. The outlook for patients with recurrent SCLC is poor. A variety of single- and multi-agent chemotherapy regimens have met with limited success in patients with recurrent SCLC, and survival is generally measured in weeks. Until recently, further chemotherapy was not widely considered appropriate for patients with relapsed SCLC. The choice of chemotherapy at relapse is dependent on many factors, including type of and response to first-line therapy, the treatment-free interval, and the patient's performance status. Intravenous topotecan (Hycamtin; GlaxoSmithKline; Philadelphia, PA) has provided oncologists and patients in many countries with an effective and tolerable therapeutic option for recurrent SCLC. The clinical profile of topotecan was established in several phase II studies and confirmed in a randomized, phase III trial versus cyclophosphamide, doxorubicin (Adriamycin; Bedford Laboratories; Bedford, OH), and vincristine (Oncovin; Eli Lilly and Company; Indianapolis, IN)--CAV. In those studies, topotecan exhibited antitumor activity in both chemosensitive and refractory disease. Further, topotecan therapy is associated with significant symptom palliation in this patient population. Because the toxicity profile of topotecan is predictable, generally manageable, and noncumulative, the agent also has potential utility in patients with a poor prognosis and/or a poor performance status. Alternative dosing regimens (lower dose, weekly) and the introduction of an oral formulation may expand the use of topotecan as a single agent and in combination therapy in the second- and first-line treatment of this disease.

Topotecan Dosing Guidelines in Ovarian Cancer: Reduction and Management of Hematologic Toxicity

Abstract: Topotecan dosing considerations and alternative dosing schedules to reduce and manage myelosuppression during the treatment of relapsed ovarian cancer were reviewed. The myelosuppression patterns from phase I, II, and III clinical trials were analyzed to evaluate the degree of hematologic toxicity and to determine risk factors predictive of myelosuppression. Additionally, recent publications of alternative topotecan doses and schedules were examined. Extent of prior therapy, prior platinum therapy (particularly carboplatin), advanced age, impaired renal function, and prior radiation therapy were identified as potential risk factors for greater hematologic toxicity after topotecan therapy. Reducing the starting topotecan dose to 1.0 or 1.25 mg/m2/day is recommended to reduce the incidence of severe myelosuppression in high-risk individuals receiving topotecan for 5 consecutive days. Hematopoietic growth factors, transfusion therapy, and schedule adjustments may also help manage myelosuppression. Alternative schedules of 3-day or weekly dosing appear to have less myelotoxicity and are currently under evaluation. The clinical aspects of topotecan-related myelosuppression and results from clinical trials indicate that the dose, and possibly the dosing schedule, of topotecan can be modified to reduce hematologic toxicity and improve tolerance without compromising efficacy. Prospective individualization of topotecan dosing may prevent or minimize dose-limiting myelosuppression and allow patients to achieve the maximum topotecan benefit by improving their ability to complete therapy with fewer treatment delays. Ongoing clinical trials evaluating alternative dosing schedules with superior hematologic tolerability may facilitate the inclusion of topotecan in combination regimens for patients with ovarian cancer. Proposed topotecan dosing guidelines to reduce and manage myelosuppression are outlined.

Quality-of-Life Considerations in Patients with Advanced Lung Cancer: Effect of Topotecan on Symptom Palliation and Quality of Life

Abstract: Key goals in the treatment of lung cancer are to improve both survival and quality of life (QOL). While formal techniques are frequently used to evaluate survival and response, such rigor is used less often in assessing the impact of treatment on quality of life. Many patients with lung cancer are elderly and have complex medical histories and a myriad of comorbidities. In these patients, with limited survival expectations, symptom palliation, quality of life, and convenience of therapy are especially important end points. Indeed, clinical trials are now incorporating symptom scores and QOL outcomes in their designs (now combined as “patient reported outcomes” or PROs). Moreover, symptom palliation correlates well with QOL and survival duration, providing further rationale for therapy selection based on these parameters. The potential palliative and QOL benefits of chemotherapy have been investigated for several agents in lung cancer trials. Of these, topotecan (Hycamtin ® ; GlaxoSmithKline; Philadelphia, PA) is the best characterized in relapsed small cell lung cancer (SCLC). In a phase III trial of topotecan versus cyclophosphamide, doxorubicin (Adriamycin ® ; Bedford Laboratories; Bedford, OH), and

Pharmacokinetic Model-Predicted Anticancer Drug Concentrations in Human Tumors

Abstract: In an era when molecular and targeted anticancer therapeutics is a major focus and when understanding drug dynamics in tumor is critical, it seems advantageous to be able to relate drug concentrations in tumors to corresponding biological end points. To that end, a novel method, based on physiologically based hybrid pharmacokinetic models, is presented to predict human tumor drug concentrations. Such models consist of a forcing function, describing the plasma drug concentration-time profile, which is linked to a model describing drug disposition in tumors. The hybrid models are originally derived from preclinical data and then scaled to humans. Integral to the scale-up procedure is the ability to derive human forcing functions directly from clinical pharmacokinetic data. Three examples of this approach are presented based on preclinical investigations with carboplatin, topotecan, and temozolomide. Translation of these preclinical hybrid models to humans used a Monte Carlo simulation technique that accounted for intrasubject and intersubject variability. Different pharmacokinetic end points, such as the AUC tumor, were extracted from the simulated human tumor drug concentrations to show how the predicted drug concentrations might be used to select drug-dosing regimens. It is believed that this modeling strategy can be used as an aid in the drug development process by providing key insights into drug disposition in tumors and by offering a foundation to optimize drug regimen design.

Ifosfamide/carboplatin/etoposide (ICE) as front‐line, topotecan/ cyclophosphamide as second‐line and oral temozolomide as third‐line treatment for advanced neuroblastoma over one year of age

Abstract: Children affected by advanced neuroblastoma have a discouraging prognosis, but intensive induction chemotherapy may increase the complete response rate. The combination of ifosfamide, carboplatin and etoposide (ICE) was used for the first time as front-line regimen in patients with stage 4 neuroblastoma over the age of 1 y. Similarly, second-line treatment for children with relapsed neuroblastoma, particularly after high-dose chemotherapy, has been unsatisfactory. The combination of topotecan and cyclophosphamide was studied in resistant or relapsed solid tumors. Furthermore, there is a need for effective palliative treatment in patients failing therapy. Temozolomide, a new dacarbazine analog with optimal oral bioavailability, is being used in an ongoing phase II study as an alternative to oral etoposide. Seventeen patients with stage 4 neuroblastoma have entered the ICE study; 15/16 (94%) major responses after induction were observed and 6/16 (37%) evaluable patients are disease free after a median of 51 mo. Twenty-one patients with relapsed/refractory disease (of whom 13 neuroblastomas) entered the topotecan/cyclophosphamide study: 7/21 (33%) patients responded. Forty-one patients entered the temozolomide study (of whom 16 had neuroblastomas): stable disease and symptom relief were obtained in 15/30 (50%) evaluable patients. Intensive induction with ICE resulted in a faster response with high response rate; a larger study with longer follow-up is needed to confirm a survival advantage. Second-line treatment was effective in obtaining remissions, some of them long lasting. Third-line treatment did not elicit measurable responses in neuroblastoma, but achieved prolonged freedom from disease progression and excellent palliation in several patients.

A mathematical model for the in vitro kinetics of the anti-cancer agent topotecan

Abstract: In this paper a compartmental modelling approach is applied to provide a mathematical description of the activity of the anti-cancer agent topotecan, and delivery to its nuclear DNA target following administration. The activity of topotecan in defined buffers is first modelled using a linear two compartment model that then forms the basis of a cell based model for drug activity in live cell experiments. An identifiability analysis is performed before parameter estimation to ensure that the model output (i.e., continuous, perfect and noise-free data) uniquely determines the parameters. Parameter estimation is performed using experimental data which offers concentrations of active and inactive forms of topotecan from high performance liquid chromatography methods.

Activity of topotecan in retinoblastoma

Abstract: Purpose: To report our experience with topotecan in children with relapsed/refractory metastatic and intraocular retinoblastoma. Patients and methods: Topotecan was administered intravenously as a 30-min infusion at a dose of 2mg/m 2 /d for five consecutive days and repeated after three weeks. If obvious progression was detected by physical examination in patients with overt extraocular disease or if progressive disease was noted after fundoscopic examination in patients with intraocular disease, a second cycle was not administered. Response was evaluated at Week 6. Results: Nine patients (6 extraocular, 3 intraocular) were treated from November 1998 to March 2002. A total of 16 cycles were administered. In patients with extraocular disease, there were three partial responses, two cases of stable disease, and one case of progressive disease. Two patients with relapsed/resistant intraocular disease had partial response, allowing local therapy to be performed, and the third patient had progressive disease. ...