Phase I clinical and pharmacology study of topotecan given daily for 5 consecutive days to patients with advanced solid tumors, with attempt at dose intensification using recombinant granulocyte colony-stimulating factor

Review : Topoisomerase I inhibitors: 1. Topotecan

Purpose. The primary objective of this article is to discuss the pharmacology, pharmacokinetics, clin ical use, and adverse effects of the approved topoisomerase I inhibitors. This is the first in a series of two articles and will focus on topotecan.

Data Sources. We reviewed the literature through a MEDLINE search of English language articles from 1985 through 1997. Relevant articles cited in the titles obtained from the MEDLINE search were also used. The following terms were used for purpose of conducting the MEDLINE search: topoisomerase inhibitors, topotecan, topo isomerase I, Hycamtin, SKF 104864.

Data Extraction. We reviewed the current literature in order to discuss the pharmacology, pharmacokinetics, clinical use, toxicity, drug inter actions, indications, formulation, dosage and ad ministration, and pharmaceutical issues surround ing the use of topotecan.

Data Synthesis. The topoisomerase I inhibi tors are new antineoplastic agents with a unique mechanism of action. Promising areas of applica tion include ovarian cancer, lung cancer, radiation sensitization, and refractory leukemias. Clinical tri als detailing its activity in these areas are pre sented.

Pilot induction regimen incorporating pharmacokinetically guided topotecan for treatment of newly diagnosed high-risk neuroblastoma: a Children's Oncology Group study

PURPOSE

To assess the feasibility of adding dose-intensive topotecan and cyclophosphamide to induction therapy for newly diagnosed high-risk neuroblastoma (HRNB).

PATIENTS AND METHODS

Enrolled patients received two cycles of topotecan (approximately 1.2 mg/m(2)/d) and cyclophosphamide (400 mg/m(2)/d) for 5 days followed by four cycles of multiagent chemotherapy (Memorial Sloan-Kettering Cancer Center [MSKCC] regimen). Pharmacokinetically guided topotecan dosing (target systemic exposure with area under the curve of 50 to 70 ng/mL/hr) was performed. Peripheral-blood stem cell (PBSC) harvest and surgical resection of residual primary tumor occurred after cycles 2 and 5, respectively. Patients achieving at least a partial response received myeloablative chemotherapy with PBSC rescue and radiation to the presurgical primary tumor volume. Oral 13-cis-retinoic acid maintenance therapy was administered twice daily for 14 days in six 28-day cycles.

RESULTS

Thirty-one patients were enrolled onto the study. No deaths related to toxicity or dose-limiting toxicities occurred during induction. Mucositis rarely occurred after topotecan cycles (9.7%) in contrast to 30% after MSKCC cycles. Thirty patients underwent PBSC collection with median 31.1 × 10(6) CD34+ cells/kg (range, 1.8 to 541.8 × 10(6) CD34+ cells/kg), all negative for tumor contamination by immunocytochemical analysis. Targeted topotecan systemic exposure was achieved in 26 (84%) of 31 patients. At the end of induction, 26 patients (84%) had tumor response and one patient had progressive disease. In the overall cohort, 3-year event-free and overall survival were 37.8% ± 9.4% and 57.1% ± 9.4%, respectively.

CONCLUSION

This pilot induction regimen was well tolerated with expected and reversible toxicities. These data support investigation of efficacy in a phase III clinical trial for newly diagnosed HRNB.

Activity of topotecan given intravenously for 5 days every three weeks in patients with advanced non-small cell lung cancer pretreated with platinum and taxanes: a phase II study

Topotecan, a semi-synthetic camptothecin analogue with topoisomerase I interaction, has shown to be an active agent in the treatment of advanced refractory lung cancer. This paper describes the authors' experience with this drug when used as a single agent in patients (pts) with advanced non-small cell lung cancer (NSCLC) refractory to platinum- and taxane-containing chemotherapy regimens. Thirty-five patients with NSCLC refractory to previous chemotherapy and KI ≥ 60% were included in the study. Their characteristics are as follows: median age of 52 years (range 43-69) and Karnofsky PS of 70 (60-80); 27 were male and 8 were female. Twenty-one (60%) patients had adenocarcinoma; eleven (31.4%), squamous cell, and three (8.5%), undifferentiated carcinoma. There was a median of two disease sites and two prior chemotherapy regimens. Topotecan was administered at a dose of 1.25 mg/m(2) I.V. daily for 5 days, repeated every 21 days until disease progression, maximal response, or intolerable toxicity. After 73 cycles, patients received a median of 2 treatment cycles (1-9). All patients except one were considered evaluable for toxicity; eight episodes (24%) of nausea/vomiting and two episodes (6%) of grade 1-2 asthenia, respectively, were reported. Four (12%) patients developed grade 1-2 anemia and two (6%) subjects suffered grade 3 anemia. Seven (21%) patients had grade 1-2 neutropenia and one (3%) presented grade 5 neutropenia. In 33 patients evaluable for activity of the 35 subjects included in the study; one (2.8%) presented a partial response; nine (25.7%) had stable disease, and 23 (65.7%) exhibited disease progression. Median time to progression and overall survival were 54 (12-210) and 70 (12-324) days, respectively. Intravenous topotecan at that dose and administration schedule displays scant activity in terms of response rate in individuals with advanced NSCLC previously treated with platinum and taxanes. The role and usefulness of chemotherapy in this setting warrants further investigation and confirmation through comparative studies.

A phase I study to characterize the safety, tolerability, and pharmacokinetics of topotecan at 4 mg/m2 administered weekly as a 30-minute intravenous infusion in patients with cancer

Topotecan pharmacokinetics at higher infusion rates (4 mg/m2 over 30 minutes) have not been studied. The authors report a pharmacokinetics and safety study of this dose in advanced cancer patients. Sixteen patients were given a 4-mg/m2 topotecan infusion intravenously (IV) over 30 minutes weekly for 3 weeks, repeated every 28 days. Pharmacokinetics were determined after the first dose. Plasma concentrations of total topotecan were measured to derive CL, V(ss), C(max), t(max), t(1/2), AUC(0-t), and AUC(0-infinity). Plasma total topotecan concentrations decreased biexponentially, with a mean CL value of 20.6 L/h, V(ss) value of 101 L, and t(1/2) value of 5.0 h. Nine significant adverse events (all hematologic) were topotecan related. Grade 3 or less adverse events included anemia, thrombocytopenia, leukopenia, and fatigue. Pharmacokinetics of the 4-mg/m2 infusion of topotecan over 30 minutes are comparable to findings from studies of lower and higher doses. Toxicities are similar to previous reports.

Chemo-sensitivity in a panel of B-cell precursor acute lymphoblastic leukemia cell lines, YCUB series, derived from children

Sensitivity to 10 anticancer drugs was evaluated in 6 childhood B-cell precursor acute lymphoblastic leukemia (BCP-ALL) cell lines. Authenticity of newly established cell lines was confirmed by genomic fingerprinting. The line YCUB-5R established at relapse was more resistant to 4-hydroperoxy-cyclophosphamide, cytarabine, L-asparaginase, topotecan, fludarabine, and etoposide than YCUB-5 from the same patient at diagnosis. Of the drugs tested, etoposide and SN-38 (irinotecan) showed highest efficacy in the panel, with 50% growth inhibition at 0.22-1.8 microg/ml and 0.57-3.6 ng/ml, respectively. This cell line panel offers an in vitro model for the development of new therapies for childhood BCP-ALL.

Topoisomerase I inhibitors for the treatment of brain tumors

Patients with primary malignant brain tumors have a poor prognosis. Standard treatment includes surgical resection, radiation therapy and chemotherapy. Topoisomerase I inhibitors such as topotecan and irinotecan (CPT-11) represent one class of chemotherapy drugs that have been used in this disease. Recent clinical trials have shown major antitumor activity in recurrent glioblastoma when adding the antiangiogenesis drug bevacizumab with CPT-11. The combination of targeted agents to topoisomerase I inhibitors represent a novel and promising approach. This review will summarize clinical trials with topoisomerase I inhibitors and discuss new treatment strategies for primary malignant brain tumors.

Upfront window trial of topotecan in previously untreated children and adolescents with poor prognosis metastatic osteosarcoma: children's Cancer Group (CCG) 7943

BACKGROUND

Patients with metastatic osteosarcoma have a poor prognosis. The objectives of the study were to determine the antitumor activity and toxicity of topotecan (daily x5) in newly diagnosed patients with metastatic osteosarcoma followed by chemotherapy (ifosfamide, carboplatin, etoposide [ICE], alternating with cisplatin and doxorubicin [CD]).

METHODS

Newly diagnosed patients (< or =30 years of age) with extensive metastatic disease (primary and > or =5 pulmonary nodules and/or bone metastases) with normal hepatic, renal, and cardiac function were eligible. Patients were eligible to receive further topotecan after standard chemotherapy if they exhibited a response. Twenty-eight patients were enrolled. Seventeen had metastases to the lung only and 11 had metastases to the bone or multiple sites. Of 28 patients enrolled, 27 could be evaluated for response. A limited dose escalation was incorporated.

RESULTS

No responses were seen in the 11 patients treated at 3 mg/m(2)/day. One partial response (PR) and 1 clinical response (CLR) were reported among 15 patients who received topotecan at 3.5 mg/m(2)/day. No dose-limiting toxicity was observed. Principal nondose-limiting toxicities were hematologic and gastrointestinal. The 2- and 5-year event-free survival rates were low, 7% and 4%, respectively, but the 2- and 5-year overall survival rates were 44% and 22%, respectively.

CONCLUSIONS

Topotecan at dose of 3.5 mg/m(2)/day can be safely administered upfront to newly diagnosed patients without excessive toxicity. Insufficient activity was seen with topotecan in this schedule to warrant further studies in osteosarcoma. The combination of ICE and CD was tolerable when delivered after initial topotecan therapy.

Involvement of Rat and Human Organic Anion Transporter 3 in the Renal Tubular Secretion of Topotecan [(S)-9-Dimethylaminomethyl-10-hydroxy-camptothecin hydrochloride]

Topotecan [(S)-9-dimethylaminomethyl-10-hydroxy-camptothecin hydrochloride] is primarily excreted into urine in humans, with approximately 49% of the dose recovered as total topotecan (topotecan lactone plus topotecan hydroxyl acid form). The renal elimination of topotecan involves tubular secretion in addition to glomerular filtration, but little is known about the molecular mechanism of the renal tubular secretion. In the present study, we investigated the transport characteristics of topotecan hydroxyl acid across the renal basolateral membrane using rat kidney slices and rat or human transporter-expressing Xenopus laevis oocytes. Pravastatin and probenecid significantly inhibited the uptake of topotecan hydroxyl acid by rat kidney slices with K(i) values of 10.6 and 8.1 microM, respectively, and p-aminohippurate was weakly inhibitory at high concentrations, whereas excess tetraethylammonium had no effect. The uptake of topotecan hydroxyl acid by oocytes injected with complementary RNA of either rat or human organic anion transporter 3 (rOAT3 or hOAT3) was greater than that of water-injected oocytes. Kinetic analysis showed that the K(m) values for rOAT3 and hOAT3 were 21.9 and 56.5 microM, respectively. Neither rOAT1 nor hOAT1 stimulated topotecan hydroxyl acid transport. These results suggest that the urinary excretion of topotecan hydroxyl acid is accounted for by transport via OAT3, as well as glomerular filtration, in both rats and humans; therefore, drug-drug interactions involving OAT3 may cause a change in clearance of topotecan.

Camptothecin and podophyllotoxin derivatives: inhibitors of topoisomerase I and II - mechanisms of action, pharmacokinetics and toxicity profile

Camptothecins represent an established class of effective agents that selectively target topoisomerase I by trapping the catalytic intermediate of the topoisomerase I-DNA reaction, the cleavage complex. The water-soluble salt camptothecin-sodium - introduced in early trials in the 1960s - was highly toxic in animals, whereas the semisynthetic derivatives irinotecan and topotecan did not cause haemorrhagic cystitis because of their higher physicochemical stability and solubility at lower pH values. Myelosuppression, neutropenia and, to a lesser extent, thrombocytopenia are dose-limiting toxic effects of topotecan. In contrast to the structurally-related topotecan, irinotecan is a prodrug which has to be converted to SN-38, its active form. SN-38 is inactivated by conjugation, thus patients with Gilbert's syndrome and other forms of genetic glucuronidation deficiency are at an increased risk of irinotecan-induced adverse effects, such as neutropenia and diarrhoea. The cytotoxic mechanism of podophyllotoxin is the inhibition of topoisomerase II. Common adverse effects of etoposide include dose-limiting myelosuppression. Hypersensitivity reactions are more common with etoposide and teniposide than with etoposide phosphate because the formulations of the former contain sensitising solubilisers. Leukopenia and thrombocytopenia occur in 65% and 80%, respectively, of patients after administration of conventional doses of teniposide. Anorexia, vomiting and diarrhoea are generally of mild severity after administration of conventional doses of topoisomerase II inhibitors. Clinical pharmacokinetic studies have revealed substantial interindividual variabilities regarding the area under the concentration-time curve values and steady-state concentrations for all drugs reviewed in this article. Irinotecan, etoposide and teniposide are degraded via complex metabolic pathways. In contrast, topotecan primarily undergoes renal excretion. Regarding etoposide and teniposide, the extent of catechol formation over time during drug metabolism may be associated with a higher risk for secondary malignancies.

Phase I study of high-dose topotecan with haematopoietic stem cell support in the treatment of ovarian carcinomas: the ITOV 01 protocol

Topotecan has demonstrated activity in ovarian carcinomas. In order to increase the tumour response rate and to define the maximum tolerated dose (MTD) of topotecan, we decided to develop a high-dose phase I regimen supported by stem cell support. High-doses schedules using a 1-day single administration have MTDs of 10.5 (24 h continuous infusion (CI)) or 22.5 mg/m2 (30 min infusion). Five-day CI induces grade IV mucositis at high doses (MTD<12 mg/m2). We chose to administer topotecan in a 5-day schedule with a 30 min daily infusion. Patients were scheduled to receive one cycle of therapy. The first dose level was 4.0 mg/m2/day x 5 days. Limiting toxicities were defined as toxic death, grade IV non-haematopoietic or haematopoietic toxicity >6 weeks. From August 1998 to April 2002, 49 patients were included. Forty-three patients have completed one course and 15 have received two cycles. One patient treated at level 7 mg/m2/day died of sepsis. Median duration of grade IV neutropenia was 9 days. Two episodes of grade IV diarrhoea were observed at level 9.5 mg/m2/day. Pharmacokinetic data were linear within the dose range of 4-9.0 mg/m2/day. The MTD was reached at 9 mg/m2/day x 5 days.

Pediatric Phase I Trials in Oncology: An Analysis of Study Conduct Efficiency

Purpose

To determine the efficacy and safety of pediatric phase I oncology trials in the era of dose-intensive chemotherapy and to analyze how efficiently these trials are conducted.

Methods

Phase I pediatric oncology trials published from 1990 to 2004 and their corresponding adult phase I trials were reviewed. Dose escalation schemes using fixed 30% dose increments were studied to theoretically determine whether trials could be completed utilizing fewer patients and dose levels.

Results

Sixty-nine pediatric phase I oncology trials enrolling 1,973 patients were identified. The pediatric maximum-tolerated dose (MTD) was strongly correlated with the adult MTD (r = 0.97). For three-fourths of the trials, the pediatric and adult MTD differed by no more than 30%, and for more than 85% of the trials, the pediatric MTD was less than or equal to 1.6 times the adult MTD. The median number of dose levels studied was four (range, two to 13). The overall objective response rate was 9.6%, the likelihood of experiencing a dose-limiting toxicity was 24%, and toxic death rate was 0.5%.

Conclusion

Despite the strong correlation between the adult and pediatric MTDs, more than four dose levels were studied in 40% of trials. There appeared to be little value in exploring dose levels greater than 1.6 times the adult MTD. Limiting pediatric phase I trials to a maximum of four doses levels would significantly shorten the timeline for study conduct without compromising safety.

A phase I trial defining the maximum tolerated systemic exposure of topotecan in combination with Carboplatin and Etoposide in extensive stage small cell lung cancer

PURPOSE

Topotecan is active in relapsed small cell lung cancer; thus, its addition to the standard carboplatin-etoposide regimen may improve outcomes in extensive-stage small cell lung cancer (ES-SCLC) patients. Significant interpatient variability in the topotecan systemic exposure results when it is dosed based on body surface area (mg/m2). The purpose of this Phase I trial was to determine the maximally tolerated systemic exposure (MTSE) of topotecan in combination with carboplatin and etoposide.

METHODS

Thirty-four chemotherapy-naïve ES-SCLC patients received topotecan in combination with carboplatin AUC 5 mg/mL*min and oral etoposide 100 mg/m2/day. Topotecan was administered as a 30-minute infusion either on Days 1-5 or Days 1-3 and the dosage was individualized to attain a topotecan lactone AUC range (ng/mL*hr) in successive patient cohorts from 7 to 23; 24 to 36; 37 to 53; 54 to 66.

RESULTS

The majority (67 percent) of the measured topotecan AUCs were within target range. Overall, 8 of 34 patients experienced Cycle 1 dose-limiting toxicity (DLT), either neutropenia or thrombocytopenia. Carboplatin administration prior to topotecan resulted in 2 of 6 patients having Cycle 1 DLT. When the administration sequence was changed (topotecan, carboplatin, etoposide), Cycle 1 hematologic toxicity decreased; however, the maximum topotecan lactone AUC of 24-36 ng/mL*hr (median dose 0.82 mg/m2) had significant cumulative hematologic toxicity. The number of topotecan doses were reduced from 5 to 3, which resulted in a maximum topotecan lactone AUC of 37 to 53 ng/mL*hr with only 1 of 6 patients having Cycle 1 DLT. Overall response rate was 71 percent with median survival of 10.8 months.

CONCLUSION

It is feasible to target topotecan lactone AUC in adult ES-SCLC patients. However, this triplet regimen resulted in considerable hematologic toxicity and has a median survival comparable to carboplatin-etoposide. Alternative, less toxic regimens should be investigated for improving survival in ES-SCLC.

Topotecan, an active new antineoplastic agent: review and current status

Topotecan (Hycamtin) is a water soluble semisynthetic analogue of the alkaloid camptothecin which has antitumour activity in preclinical models in vitro and in vivo. A range of Phase I studies has been performed and a daily x 5 iv. schedule, which showed most promising evidence of activity, was selected for extensive clinical evaluation. To date, topotecan has been shown to be active in a number of malignancies, including metastatic ovarian cancer, recurrent small cell lung cancer (SCLC), non-small cell lung cancer (NSCLC), breast cancer, colorectal cancer and myelodysplastic syndrome. In ovarian cancer, response rates of around 15% were identified in patients who had failed standard chemotherapy, and in a randomised, comparative study with paclitaxel response rates of 20% (topotecan) and 13% (paclitaxel) were observed. In addition, overall time to progression was impressive at 23 weeks (topotecan) compared with 14 weeks (paclitaxel). In recurrent SCLC, topotecan has shown good activity in sensitive patients with a response rate of 39%, although the response rate in refractory patients was considerably lower (7%). Median survival of all patients was 5.4 months, acceptable for this difficult clinical scenario. Topotecan is well-tolerated in the majority of patients and subjective toxicities are uncommon. The principal side-effect is myelosuppression, mainly neutropenia. Serious clinical sequelae are relatively uncommon and non-cumulative. Nonhaematological toxicities are generally mild and not dose-limiting. In clinical use, topotecan has exhibited activity in multiple tumour types, with a side-effect profile that is predictable and manageable. The drug is under evaluation in other tumour types and in combination chemotherapy regimens.

A predictive model of human myelotoxicity using five camptothecin derivatives and the in vitro colony-forming unit granulocyte/macrophage assay

PURPOSE

Many promising anticancer drugs are limited by myelosuppression. It is difficult to evaluate human myelotoxicity before a Phase I study because of the susceptibility of humans and animals to hematotoxicity. The purpose of this study was to establish a reliable method to predict the human maximum tolerated dose (MTD) of five camptothecin derivatives: SN-38, DX-8951f, topotecan, 9-aminocamptothecin, and camptothecin.

EXPERIMENTAL DESIGN

The myelotoxicity of SN-38 and DX-8951f were evaluated on bone marrow from mice, dogs, and humans using a 14-day colony-forming unit, granulocyte-macrophage (CFU-GM) assay to determine the 50%, 75%, and 90% inhibitory concentration values (IC50, IC75, and IC90, respectively).

RESULTS

Species differences in myelotoxicity were observed for SN-38 and DX-8951f. Using human and murine IC90s for myelotoxicity of these compounds and other camptothecin compounds (topotecan, 9-aminocamptothecin, and camptothecin), in vivo toxicological data, and pharmacokinetic parameters (data referred to in the literature), human MTDs were predicted retrospectively. The mechanism-based prediction model that is proposed uses the in vitro camptothecin assay and in vivo parameters on the basis of free fraction of area under the concentration-curve at the MTD (r2 = 0.887) and suggests that the human MTDs were well predicted for the five camptothecin derivatives by this model rather than by other models.

CONCLUSION

The human MTDs of the camptothecin drugs were successfully predicted using the mechanism-based prediction model. The application of this model for in vitro hematotoxicology could play an important role for the development of new anticancer agents.

Review of the use of topotecan in ovarian carcinoma

Ovarian cancer is the fifth leading cause of cancer deaths in women. The majority of patients present with advanced disease and relapse after first-line platinum-based chemotherapy; therefore, many proceed to treatment with salvage chemotherapy. Currently available treatment options are generally no longer curative in the relapse setting; hence, the emphasis of treatment is towards disease control and palliation of symptoms. There are several agents available for the treatment of relapsed ovarian carcinoma, of which topotecan is one of the most widely studied and characterised. This review aims to evaluate the role of topotecan in the management of this disease by considering the properties of the compound, the clinical efficacy in Phase II and III studies, its role in first- and second-line treatment and alternative dosing strategies to overcome toxicity.

Topoisomerase I Inhibitors in the Treatment of Gastrointestinal Cancer: From Intravenous to Oral Administration

This article reviews the current status of the topoisomerase I (top I) inhibitors in the treatment of gastrointestinal (GI) malignancies. We focus on oral drug administration, the mode of administration that is generally preferred by patients with cancer. However, the great majority of the studies have been performed with intravenous (I.V.) administration. The most extensively investigated GI malignancy in phase I/II studies is colorectal cancer (CRC), for which I.V. irinotecan is currently approved in the United States and Europe. We discuss the activity and efficacy of irinotecan as a single agent in CRC and in combination regimens. Also, results obtained with monotherapy and in combination treatment in other GI malignancies such as esophageal, gastric, and pancreatic cancer are discussed. Few phase I studies have been performed with oral irinotecan and its clinical activity has not yet been fully determined. Several top I inhibitors are discussed, including topotecan, 9-aminocamptothecin, rubitecan, exatecan, and lurtotecan. None of these agents, given orally or intravenously, have shown activity in CRC similar to that of I.V. irinotecan. However, several agents show promising results in other GI malignancies, eg, rubitecan and exatecan in pancreatic cancer. A complicating factor in the oral administration of the top I inhibitors is the often encountered low and variable oral bioavailability. This can partly be explained by the high affinity for the drug efflux pumps BCRP (ABCG2) and P-glycoprotein, which are highly expressed in the epithelial apical membrane of the GI tract. A novel approach to improve the oral bioavailability of the top I inhibitors by temporary blockade of the drug transporter BCRP is described.

Phase I evaluation of docetaxel and topotecan for patients with advanced solid tumors

BACKGROUND

The authors administered a combination of docetaxel and topotecan with granulocyte-colony-stimulating factor (G-CSF) support in a Phase I study to define the maximum tolerated dose (MTD) of this regimen.

METHODS

Patients with advanced-stage solid tumors were eligible for this trial if they had a Zubrod performance status of </= 2 and normal renal, hepatic, and bone marrow function. No previous therapy with taxanes or topoisomerase inhibitors was allowed. The authors administered both docetaxel and topotecan in a dose-escalated manner until the MTD was reached. Docetaxel was given on Day 1 of each cycle before topotecan, which was administered intravenously on Days 1-3. Granulocyte-colony-stimulating factor (G-CSF) support with 5 microg/kg subcutaneous injections was initiated on Day 4 and continued until the absolute granulocyte count recovered to 2000/microL. Treatment cycles were repeated every 21 days.

RESULTS

Of the 11 patients enrolled in the current study, all were evaluable for toxicity and 10 were evaluable for response. A median of three treatment cycles was received (range, one to nine treatment cycles). The dose-limiting toxicity was Grade 4 (according to the National Cancer Institute Common Toxicity Criteria for Adverse Events [version 2.0]). neutropenia with fever. The MTD was 75 mg/m2 of docetaxel on Day 1 and 1.4 mg/m2 of topotecan on Days 1-3. There was one complete response and one partial response in patients with nasopharyngeal carcinoma and one partial response in a patient with small cell lung carcinoma (SCLC). The response durations were 24 weeks, 29 weeks, and >/= 244 weeks, respectively. At the time of last follow-up, both patients with nasopharyngeal carcinoma were still alive at 241 weeks and 244 weeks, respectively.

CONCLUSIONS

This trial demonstrated that a regimen of docetaxel and topotecan with G-CSF support was generally well tolerated and had promising activity in patients with nasopharyngeal and SCLC.

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

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.

Amifostine pretreatment for protection against topotecan-induced hematologic toxicity: results of a multicenter phase III trial in patients with advanced gynecologic malignancies

OBJECTIVE

To determine if amifostine could reduce the hematologic toxicity associated with topotecan.

METHODS

Thirty patients with recurrent/refractory gynecologic malignancies were randomized to receive topotecan (TOPO) (1.5 mg/m(2)/day days 1-5) with or without amifostine (AMI/TOPO) (500 mg/m(2)/day days 1-5) every 3 weeks for six cycles. The primary study endpoints were the incidence of grade 3 and 4 neutropenia.

RESULTS

Fifteen patients were randomized to each arm for a total of 49 TOPO and 53 AMI/TOPO cycles. Patient characteristics and pretreatment ANC were similar between groups. Topotecan 1.5 mg/m(2)/day days 1-5 was initially administered to seven patients. Five developed neutropenic fevers, one an uncomplicated grade 4 neutropenia, and the other an uncomplicated grade 3 neutropenia. There were two treatment-related deaths due to sepsis (one in each treatment arm). The starting dose was thereafter reduced to 1.25 mg/m(2)/day days 1-5 every 21 days. No treatment related deaths occurred after this dose reduction. The incidence of combined grade 3/4 neutropenia was reduced from 67% (33/49 cycles) to 38% (20/53 cycles) with the addition of amifostine (P = 0.003; OR 0.29; 95% CI 0.12-0.71).

CONCLUSIONS

Topotecan at 1.5 mg/m(2)/day days 1-5 in heavily pretreated patients resulted in excessive toxicity not manageable with amifostine. At the reduced topotecan dose (1.25 mg/m(2) x 5 days), pretreatment with amifostine reduced the hematologic toxicity associated with topotecan chemotherapy in women with recurrent/refractory gynecologic malignancies.

The camptothecins

Supported by detailed understanding of their mechanism of action, and facilitated by chemical manipulations that have amplified their solubility, the camptothecins have advanced to the forefront of several areas of therapeutic and developmental chemotherapy. Additive and synergistic laboratory interactions with other cytotoxic drugs have been exploited to allow development of camptothecin-based multidrug regimens, which are showing important activity in several malignancies. Topotecan and irinotecan are already in widespread use in clinical practice, and newer agents with promising preclinical activity are in various stages of clinical assessment. As knowledge of molecular and biochemical mechanisms of action and resistance continues to expand, newer and better camptothecin-based strategies for treatment of malignant disease are likely to evolve.

A dose-escalation study of weekly topotecan, cisplatin, and gemcitabine front-line therapy in patients with inoperable non-small cell lung cancer

PURPOSE

To determine the optimal dose of combination topotecan, cisplatin, and gemcitabine in advanced non-small cell lung cancer patients.

MATERIALS AND METHODS

This single-center, single-practice, phase I trial enrolled chemotherapy-naïve patients with inoperable stage IIIB/IV disease. Initial treatment was topotecan (0.5-2.0 mg/m(2)), cisplatin (20 mg/m(2)), and gemcitabine (1,000 mg/m(2)) on days 1, 8, and 15 of a 28-day cycle. Dose-limiting thrombocytopenia at week 3 necessitated less frequent gemcitabine dosing (days 1 and 15 of each cycle). Thereafter, topotecan dose escalation proceeded to the target dose of 2 mg/m(2).

RESULTS

Thirty patients were enrolled and evaluable for toxicity assessment. Treatment was extremely well tolerated: only one grade 4 adverse event (leukopenia); no hospitalizations for treatment-related toxicities; no fever/neutropenia. Although no dose-limiting toxicities developed, 1.75 mg/m(2) topotecan is considered optimal and recommended for further study because it was well tolerated, active, and did not require dose adjustments or delays in therapy. Eleven of 29 (38%) evaluable patients achieved a partial response. Median survival was 38 weeks (range 4-110 weeks), median progression-free survival was 17 weeks, and the 1-year survival rate was 33%. Two patients remain alive after 108-122 weeks of follow-up.

CONCLUSION

A 28-day cycle of topotecan (1.75 mg/m(2) days 1, 8, 15), cisplatin (20 mg/m(2) days 1, 8, 15), and gemcitabine (1,000 mg/m(2) days 1, 15) was a safe and well-tolerated outpatient treatment for advanced non-small cell lung cancer. The favorable preliminary efficacy and safety of this regimen suggest that further study in phase II trials, including quality-of-life end points, is warranted.

Sequential administration of cisplatin-etoposide followed by topotecan in patients with extensive stage small cell lung cancer. A multicenter phase II study

PURPOSE

To evaluate the activity of the sequential administration of cisplatin-etoposide (PE) followed by topotecan (TOP) in patients with extensive stage small cell lung cancer (SCLC).

PATIENTS AND METHODS

Previously untreated patients with extensive stage SCLC received 4 cycles of cisplatin 75 mg/m(2) IV on day 1 and etoposide 100 mg/m(2) IV on days 1-3 every 21 days followed by 4 cycles of TOP 1.5 mg/m(2) IV on days 1-5 every 21 days.

RESULTS

Thirty-eight patients were entered in the study. Their median age was 63 years and the performance status (WHO) was 0 for 5, 1 for 25 and 2 for 8 patients. All patients were evaluable for toxicity and 32 for response to PE and 25 to TOP. Of the 38 patients receiving PE, 1 (3%) patient achieved complete response (CR) and 17 (45%) partial responses (PR) for an overall response rate to PE of 47% (95% confidence interval: 36.7-68.5%). Four (23.5%) of the 17 patients with PR after PE, achieved CR with TOP. None of the patients with stable or progressive disease after PE responded to TOP. The response rate of the 27 patients receiving TOP following PE was 15% (95% confidence interval: 1.4-28.2%). After a median follow up of 9 months, the median duration of response was 6.5 months, the time to tumor progression 6.5 months, the median survival 8.5 months and the 1-year survival 34%. A total of 136 cycles of PE and 89 cycles of TOP have been administered with a median of 4 cycles/patient for each regimen. There were 2 toxic deaths after PE associated with grade IV febrile neutropenia. Treatment delays due to toxicity occurred in 17 (12%) cycles of PE and 20 (22%) cycles of TOP while doses were reduced in 7 (5%) and 4 (4%) cycles, respectively. Grade 3-4 neutropenia, thrombocytopenia and febrile neutropenia occurred in 24, 2 and 3% of PE cycles and 21, 12 and 1% of TOP. Non-hematologic toxicity was mild. The delivered dose intensity was 100% for PE and 93% for TOP.

CONCLUSIONS

The sequential administration of TOP after PE is associated with manageable toxicity and may increase the number of CRs in patients with chemosensitive extensive stage SCLC. However, based on this data and the lack of survival benefit in a previous phase III study, the sequential regimen should not be used outside of a clinical trial.

ZD0473 combined with other chemotherapeutic agents for the treatment of solid malignancies

Platinum-based combination chemotherapy regimens are the mainstay of current treatments for advanced solid malignancies. Preclinical in vitro studies have shown synergism with ZD0473 in combination with several agents, including vinorelbine and topotecan. This paper reviews the tolerability and activity observed with ZD0473 in combination with vinorelbine or topotecan, in two Phase I dose-escalating studies in patients with advanced, solid, refractory malignancies. Twenty-four patients were included in the ZD0473 plus vinorelbine trial and were treated with doses of ZD0473 60-150 mg/m2 and vinorelbine 15-25 mg/m2. In this trial, dose-limiting toxicity comprised non-haematological events and the most common grade 3/4 toxicities included neutropenia (54.2%), thrombocytopenia (29.2%) and anaemia (20.8%). Eleven patients were included in the ZD0473 plus topotecan trial and were treated with ZD0473 60-90 mg/m2 and topotecan 0.5 mg/m2/day for 3 or 5 days. In this trial, dose-limiting toxicity comprised haematological events and the most common grade 3/4 toxicities included thrombocytopenia (63.6%), neutropenia (36.4%) and anaemia (18.2%). No objective responses were observed in either trial, but disease stabilisation occurred in 29.2% and 27.3% of patients in the vinorelbine and topotecan trials, respectively.

Efficacy of low-dose topotecan in second-line treatment for patients with epithelial ovarian carcinoma

BACKGROUND

The high incidence of dose-limiting myelosuppresion using the U.S. Food and Drug Administration-approved topotecan dose of 1.5 mg/m(2) for 5 days every 3 weeks may have limited its utility in the treatment of patients with epithelial ovarian carcinoma. The objective of the study was to evaluate the treatment results and toxicity of a low-dose topotecan regimen as second-line treatment for patients with epithelial ovarian carcinoma.

METHODS

A retrospective analysis was conducted of 203 consecutive patients with primary epithelial ovarian carcinoma who were referred to the Finsen Center during the period from June, 1996 to June, 2000. Eligibility criteria included histopathologically documented, International Federation of Gynecology and Obstetrics (FIGO) Stage IC-IV epithelial ovarian carcinoma; first-line treatment with paclitaxel and a platinum compound; and second-line treatment with topotecan (1.0 mg/m(2) intravenously for 5 days every 3 weeks). Efficacy and toxicity were compared with published results from pivotal trials using the approved dose of topotecan of 1.5 mg/m(2) for the same indication.

RESULTS

A total of 56 patients received second-line treatment with the reduced-dose topotecan regimen because of refractory, persistent, or recurrent disease. In the subgroup of patients with platinum-resistant and paclitaxel-resistant disease (n = 43 patients), the response rate of 11.6% (95% confidence interval [95%CI], 3.9-25.1%) was similar to the response rate of 12.4% (95%CI, 6.9-19.9%) in a pivotal trial using standard-dose topotecan. In patients with platinum-resistant and paclitaxel-resistant disease, the median progression free survival and overall survival from the first day of second-line topotecan treatment were 2.7 months (range, 0.7-19.5 months) and 6.0 months (range, 1.0-32.8 months), respectively. In a multivariate Cox analysis, the initial performance status (0 vs. 1-2; P = 0.040; hazard ratio [HR], 2.05) and the performance status at the time of second-line treatment (0 vs. 1-2; P < 0.001; HR, 4.50) were identified as independent prognostic factors for overall survival from the start of second-line treatment. Grade 4 neutropenia was noted in only 5.1% of reduced-dose topotecan cycles (95%CI, 2.8-8.4%) compared with 33% and 57% of standard-dose cycles in pivotal studies.

CONCLUSIONS

Topotecan at a dose of 1.0 mg/m(2) has similar efficacy based on response rate and lower toxicity compared with the approved schedule of 1.5 mg/m(2) for 5 days every 3 weeks in second-line treatment for patients with platinum-resistant and paclitaxel-resistant epithelial ovarian carcinoma. However, a comparison of different topotecan doses and schedules preferably should be made in a randomized setting in well-characterized populations with regard to established prognostic factors.

Cisplatin-etoposide alternating with topotecan in patients with extensive stage small cell lung cancer (SCLC). A multicenter phase II study

PURPOSE

In order to investigate the feasibility of a potentially non-cross resistant drug regimen, we alternated cycles of cisplatin-etoposide with topotecan as front-line treatment in patients with extensive stage small cell lung cancer (SCLC).

PATIENTS AND METHODS

Thirty-six previously untreated patients with extensive stage SCLC received cisplatin 75 mg/m(2) IV on day 1 and etoposide 100 mg/m(2) IV on days 1-3 on cycles one, three, five and seven and topotecan 1.5 mg/m(2) IV on days 1-5 on cycles two, four, six and eight. Cycles were repeated every 21 days. Patients' median age was 60 years and performance status (WHO) was 0 for 13, 1 for 20 and 2 for three patients. All patients were evaluable for response and toxicity.

RESULTS

Five (14%) patients achieved a complete response and 18 (50%) a partial response for an overall response rate of 64% (95% confidence interval: 48.2-79.6%). After a median follow up of 10 months, the median duration of response was 5.5 months, the time to tumor progression 8 months and the probability of 1-year survival 48.9%. A total of 126 cycles of cisplatin-etoposide and 117 cycles of topotecan were administered with a median number of 4 cycles/patient for each regimen. There were no toxic deaths. Treatment delays due to toxicity occurred in 13 (10%) cycles after cisplatin-etoposide and 16 (14%) cycles after topotecan while doses were reduced in seven (6%) and five (4%) cycles, respectively. Grade 3-4 neutropenia, thrombocytopenia and febrile neutropenia complicated 13, 1 and 3% of cisplatin-etoposide cycles and 28, 6 and 1% of topotecan, respectively. Non-hematologic toxicity was mild. The delivered dose intensity was 96% for cisplatin and etoposide and 98% for topotecan.

CONCLUSIONS

The alternating administration of cisplatin-etoposide and topotecan is a feasible, active and well-tolerated regimen in patients with extensive stage SCLC.

SWOG-9510: evaluation of topotecan in hormone refractory prostate cancer: a Southwest Oncology Group study

BACKGROUND

Prostate cancer is the most common malignancy in American men, and as many as 70% of those initially treated for localized disease will ultimately progress and be considered candidates to receive therapy for metastatic cancer [Fuks et al.: Int J Radiat Oncol Bio Phys 21:537-547, 1991; Chodak et al.: N Engl J Med 330:246-248, 1994]. Although most will respond initially to hormone manipulation, essentially all will fail and require additional therapy. No standard chemotherapy approach has been shown to prolong survival significantly, and new agents are desperately needed. Topotecan is a new topoisomerase-1 inhibitor whose early investigation suggested possible activity in hormone-refractory prostate cancer.

METHODS

In this phase II trial, patients having failed one or two prior androgen ablative therapies were treated with 21-day continuous intravenous infusions of topotecan at a dose of 0.5 mg/m(2) per day every 28 days.

RESULTS

Twenty-six eligible patients were entered on the study. There were no confirmed tumor responses. Median survival was 9 months. The most common toxicities were hematologic, with 8 of 24 assessable patients experiencing grade 4 toxicity.

CONCLUSION

Topotecan infusions at this dose are ineffective in the management of hormone-refractory prostate cancer.

Increased oral bioavailability of topotecan in combination with the breast cancer resistance protein and P-glycoprotein inhibitor GF120918

PURPOSE

We discovered that breast cancer resistance protein (BCRP), a recently identified adenosine triphosphate-binding cassette drug transporter, substantially limits the oral bioavailability of topotecan in mdr1a/1b(-/-) P-glycoprotein (P-gp) knockout and wild-type mice. GF120918 is a potent inhibitor of BCRP and P-gp. The aim was to increase the bioavailability of topotecan by GF120918.

PATIENTS AND METHODS

In cohort A, eight patients received 1.0 mg/m(2) oral topotecan with or without coadministration of one single oral dose of 1,000 mg GF120918 (day 1 or day 8). In cohort B, eight other patients received 1.0 mg/m(2) intravenous topotecan with or without 1,000 mg oral GF120918 to study the effect of GF120918 on the systemic clearance of topotecan.

RESULTS

After oral topotecan, the mean area under the plasma concentration-time curve (AUC) of total topotecan increased significantly from 32.4 +/- 9.6 microg.h/L without GF120918 to 78.7 +/- 20.6 microg.h/L when GF120918 was coadministered (P =.008). The mean maximum plasma concentration of total topotecan increased from 4.1 +/- 1.5 microg/L without GF120918 to 11.5 +/- 2.4 microg/L with GF120918 (P =.008). The apparent bioavailability in this cohort increased significantly from 40.0% (range, 32% to 47%) to 97.1% (range, 91% to 120%) (P =.008). Interpatient variability of the apparent bioavailability was 17% without and 11% with GF120918. After intravenous administration of topotecan, coadministration of oral GF120918 had a small but statistically significant effect on the AUC and systemic clearance of total topotecan but no statistically significant effect on maximum plasma concentration and terminal half-life of total topotecan.

CONCLUSION

Coadministration of the BCRP and P-gp inhibitor GF120918 resulted in a significant increase of the systemic exposure of oral topotecan. The apparent oral bioavailability increased from 40.0% without to 97.1% with GF120918.

Phase II evaluation of 3-day topotecan with cyclophosphamide in the treatment of recurrent ovarian cancer

OBJECTIVE

The aim of this trial was to investigate the toxicity and efficacy of a 3-day topotecan administration schedule in combination with cyclophosphamide in the management of recurrent ovarian cancer.

METHODS

Patients with recurrent measurable ovarian cancer who had up to two prior chemotherapy regimens for the management of their disease participating in this phase II trial were to receive topotecan at a dose of 1.25 mg/m(2)/day x 3 days in combination with cyclophosphamide at 600 mg/m(2) on Day 1 every 21 days. Dose escalation and reductions were permitted.

RESULTS

A total of 36 patients (median age = 65; range 37-84) were treated with this combination regimen. Seventeen were platinum-sensitive and 19 were platinum-resistant. A total of 169 cycles of chemotherapy was administered (median = 4; range 1-10). Major toxicity included grade 4 neutropenia (68.6%), neutropenic fever (7.1%), grade 3 thrombocytopenia (18.3%), and requirement for blood transfusion (19.5%). Dose escalation was possible in 3 (8.3%), and dose reduction was required in 14 (38.9%) patients. Overall response rate was 25 and 44.5% stable disease. Median progression-free interval and overall survival was 5.4 and 23.5 months, respectively, independent of platinum sensitivity.

CONCLUSION

The 3-day topotecan schedule in combination with cyclophosphamide appears to have good activity in recurrent ovarian cancer regardless of platinum sensitivity. Neutropenia was the only severe toxicity and was less prevalent than other reported trials of topotecan. This tolerable regimen offers patients more convenience and appears to have moderate activity.

Protracted intermittent schedule of topotecan in children with refractory acute leukemia: a pediatric oncology group study

PURPOSE

To determine dose-limiting toxicity (DLT) and maximum-tolerated dose (MTD) of a protracted, intermittent schedule of daily 30-minute infusions of topotecan (TPT) for up to 12 consecutive days, every 3 weeks, in children with refractory leukemia.

PATIENTS AND METHODS

Forty-nine children were enrolled onto this phase I trial (24 with acute nonlymphoblastic leukemia [ANLL] and 25 with acute lymphoblastic leukemia [ALL]). TPT dosage was escalated from 2.0 to 5.2 mg/m(2)/d for 5 days and 2.4 mg/m(2)/d from 7 days to the same dose for 9 and 12 days in cohorts of three to six patients when no DLT was identified. TPT pharmacokinetics were studied in 33 children once or twice (first and last doses in patients who received TPT for > 7 days).

RESULTS

Seventy assessable courses of TPT were administered to 49 children who had refractory leukemia. DLTs were typhlitis, diarrhea, and mucositis, and the MTD was 2.4 mg/m(2)/d for 9 days in this group of heavily pretreated children. In 33 patients, the median TPT lactone clearance after the first dose was 19.2 L/h/m(2) (range, 9.4 to 45.9 L/h/m(2)) and did not change during the course. There were significant responses (one complete response [CR] and four partial responses [PR] in patients with ANLL and one CR and two PRs in patients with ALL), and all but one were at dosages of TPT given for at least 9 days.

CONCLUSION

The MTD was 2.4 mg/m(2)/d for 9 days. Further testing is warranted of TPT's schedule dependence in children with leukemia.

Improved therapeutic index of lower dose topotecan chemotherapy in recurrent ovarian cancer

OBJECTIVE

Topotecan (1.5 mg/m(2)) administered daily for 5 consecutive days of a 21-day cycle is an established chemotherapeutic regimen in recurrent ovarian cancer. However, noncumulative myelosuppression has limited its use by many clinicians. We sought to determine whether a lower dose of topotecan could provide comparable tumor activity and higher tolerability in pretreated ovarian cancer patients.

METHODS

A retrospective chart review was conducted on recurrent ovarian, peritoneal, or fallopian tube cancer patients with measurable disease or elevated cancer antigen 125 levels (evaluable disease). Patients were treated with topotecan (1.0 mg/m(2)) given by 30-min intravenous infusion for 5 consecutive days every 21 days until disease progression or unacceptable toxicity.

RESULTS

Treatment records from 37 women who had been treated with a median of 3 courses (range, 1 to 17) of lower dose topotecan were evaluated; all were evaluable for tolerability and 36 were evaluable for response. Patients had received a median of 3 (range, 1 to 6) previous treatments. The overall response rate was 22% (8/36); the response rates for patients with evaluable disease and measurable disease were 35.7 (5/14) and 13.6% (3/22), respectively. An additional 8 patients (22%) achieved stable disease. Grade 4 neutropenia, thrombocytopenia, and anemia occurred in 48.6, 5.4, and 5.4% of patients, respectively. Granulocyte colony-stimulating factor support was used in 37% of patients, including 5 who experienced febrile neutropenia.

CONCLUSION

Topotecan at 1.0 mg/m(2) x 5 days every 21 days is active in platinum- and paclitaxel-resistant ovarian cancer, with significant improvements in hematologic toxicity. In heavily pretreated patients-topotecan can be safely given at reduced doses without apparent loss of efficacy.

A dose escalation study of topotecan in combination with epirubicin in pretreated patients with small-cell lung cancer

PURPOSE

To define the dose-limiting toxicities (DLTs) and the maximum tolerated doses (MTDs) of topotecan in combination with epirubicin in pretreated patients with small-cell lung cancer (SCLC).

PATIENTS AND METHODS

Twenty-seven SCLC patients with performance status (WHO) of 0-2 and adequate renal, hepatic, and bone marrow function who had failed EP-containing front-line chemotherapy entered the study. Patients received escalated doses of topotecan (starting dose 0.5 mg/m(2)) for 5 days and epirubicin (starting dose 40 mg/m(2)) on day 8, every 28 days.

RESULTS

All patients were assessable for toxicity and 20 for response. The MTD was topotecan 0.90 mg/m(2) and epirubicin 40 mg/m(2) with neutropenia being the most common dose-limiting event. Seventy-three courses were administered. Grade 3-4 neutropenia occurred in 22 (30%) courses, grade 3-4 anemia in 7 (10%), and grade 3-4 thrombocytopenia in 11 (15%). Seven courses were complicated with fever and one patient died of neutropenic sepsis. Grade 3-4 non-hematologic toxicity was mild and infrequent with only grade 2-3 asthenia occurring in 16 (22%) courses. Among 20 patients who were evaluable for response, 16 (80%) were refractory to prior treatment. One patient with refractory disease (5%) achieved a complete response of 14 weeks duration and four experienced stabilization of the disease.

CONCLUSIONS

The combination of topotecan 0.90 mg/m(2) on days 1-5, with epirubicin 40 mg/m(2) on day 8, administered every 28 days is a feasible outpatient regimen which merits further evaluation in patients with chemosensitive disease.

A Phase II study of topotecan in patients with squamous cell carcinoma of the cervix: a gynecologic oncology group study

OBJECTIVE

The toxicity and activity of intravenous topotecan were assessed in a multicenter Phase II study (GOG 76-U) in patients with advanced, recurrent, or persistent squamous cell carcinoma of the uterine cervix.

METHODS

Intravenous topotecan was administered at 1.5 mg/m2 per day for 5 consecutive days every 4 weeks in patients without prior chemotherapy, aside from chemosensitizing agents used in conjunction with radiotherapy. The study required histologic confirmation of primary diagnosis, adequate performance status, and measurable disease to assess response. A two-stage design for accrual was used to allow for early termination of the study should inadequate response or excessive toxicity be an issue. Modifications of dose were based on hematologic toxicity. Treatment was continued until progression of disease was documented or adverse effects prohibited further therapy.

RESULTS

A total of 49 patients were entered on study: of these 5 were never treated, and 1 was not evaluable for response. More than 88% (38 of 43 patients) had received prior radiotherapy. A median of two courses were administered per patient with a range of 1 to 14 cycles. Grade 4 neutropenia occurred in 68% and grade 4 thrombocytopenia in 18% of patients. Nonhematologic toxic effects were infrequent and not dose-limiting. The overall response rate (complete and partial) was 18.6%. The median progression-free survival was 2.4 months.

CONCLUSIONS

Topotecan administered at this dose and schedule demonstrated moderate activity albeit at a cost of substantial hematologic toxicity in patients with advanced, recurrent, or persistent squamous cell carcinoma of the cervix.

Phase I trial of multiple cycles of high-dose carboplatin, paclitaxel, and topotecan with peripheral-blood stem-cell support as front-line therapy

PURPOSE

To determine the safety and feasibility of delivering multiple cycles of front-line high-dose carboplatin, paclitaxel, and topotecan with peripheral-blood stem-cell (PBSC) support.

PATIENTS AND METHODS

Patients were required to have a malignant solid tumor for which they had received no prior chemotherapy. Mobilization of PBSC was achieved with either filgrastim alone or in combination with cyclophosphamide and paclitaxel. Patients then received three or four cycles of high-dose carboplatin (area under the concentration-time curve [AUC] 16), paclitaxel (250 mg/m(2)), and topotecan (10-15 mg/m(2)), with the latter two agents administered as 24-hour infusions and supported with PBSC and filgrastim. Cycles were repeated every 28 days.

RESULTS

Twenty patients were enrolled onto the trial and were assessable for toxicity and clinical outcome. Dose-limiting toxicities were stomatitis and prolonged hematopoietic recovery. The maximum-tolerated dose of topotecan was 12.5 mg/m(2) when given with high-dose carboplatin and paclitaxel for three cycles. Four cycles were able to be given with a dose of topotecan of 10 mg/m(2). The pharmacokinetics of each compound were not affected by the other agents. Eleven (85%) of 13 patients with assessable disease responded.

CONCLUSION

Multiple cycles of high-dose carboplatin, paclitaxel, and topotecan can be safely administered with filgrastim and PBSC support. The recommended doses for phase II study are carboplatin AUC 16, paclitaxel 250 mg/m(2), and topotecan 10 mg/m(2). Trials are currently being conducted with this regimen as front-line treatment in patients with advanced ovarian cancer and extensive small-cell carcinoma. This approach remains experimental and should be used only in the context of a clinical trial.

Modulation of camptothecin analogs in the treatment of cancer: a review

The topoisomerase I inhibitors reviewed in this paper are all semisynthetic analogs of camptothecin (CPT). Modulation of this intranuclear enzyme translates clinically in to antitumor activity against a broad spectrum of tumors and is therefore the subject of numerous investigations. We present preclinical and clinical data on CPT analogs that are already being used in clinical practice [i.e. topotecan and irinotecan (CPT-11)] or are currently in clinical development (e.g. 9-aminocamptothecin, 9-nitrocamptotecin, lurtotecan, DX 8951f and BN 80915), as well as drugs that are still only developed in a preclinical setting (silatecans, polymer-bound derivates). A variety of different strategies is being used to modulate the systemic delivery of this class of agents, frequently in order to increase antitumor activity and/or reduce experienced side effects. Three principal approaches are discussed, including: (i) pharmaceutical modulation of formulation vehicles, structural alterations and the search for more water-soluble prodrugs, (ii) modulation of routes of administration and considerations on infusion duration, and (iii) both pharmacodynamic and pharmacokinetic biomodulation.

Evaluation of topotecan and etoposide for non-Hodgkin lymphoma: correlation of topoisomerase-DNA complex formation with clinical response

BACKGROUND

Topotecan, a topoisomerase I inhibitor, acts by stabilizing the topoisomerase DNA cleavage complex. Etoposide, a topoisomerase II inhibitor, mediates antitumor activity by stabilizing cleavage complex formed between topoisomerase II and DNA. These two agents have therapeutic activity in non-Hodgkin lymphoma. The authors report Phase I data of topotecan and etoposide combination for patients with recurrent or refractory non-Hodgkin lymphoma and correlation of topoisomerase-DNA complex formation to clinical response.

METHODS

Twenty-two patients with recurrent or refractory aggressive non-Hodgkin lymphoma were treated at four dose levels of topotecan (1 mg/m(2)/day to 2.5 mg/m(2)/day). Topotecan was given at a 30-minute infusion daily with etoposide 150 mg/m(2)/day, both for 5 days. Topoisomerase-DNA covalent complex formation was measured using in vivo link assay, whereas topoisomerase I, IIalpha, and IIbeta in RNA expression levels were determined by reverse transcription-polymerase chain reaction in blood samples. The relation of these levels to clinical response was studied.

RESULTS

The maximum tolerated dose of topotecan was 2.0 mg/m(2)/day for 5 days. Oropharyngeal mucositis was dose-limiting. Of 21 examinable patients, 3 patients achieved complete remission, and 5 patients achieved partial remission. Of six untreated patients who experienced a recurrence, three had complete remission, and the other three had partial remission. Drug-induced topoisomerase-DNA complex formation was observed throughout the treatment in blood samples of all the patients who responded. However, only 4 of 13 patients, who did not respond, formed covalent complex at all time points. This was statistically significant (P = 0.024). In all patients, expression levels of topoisomerase I and IIbeta mRNA remained similar to pretreatment levels, whereas topoisomerase IIalpha mRNA levels decreased dramatically by the third day.

CONCLUSION

The recommended Phase II dose of topotecan with etoposide of 150 mg/m(2)/day for 5 days was 2.0 mg/m(2)/day for 5 days. Topoisomerase-DNA complex formation correlated with response to treatment.

Phase I topotecan preparative regimen for high-risk neuroblastoma, high-grade glioma, and refractory/recurrent pediatric solid tumors

We evaluated the toxicity and maximum tolerated dose of topotecan in a novel myeloablative regimen as treatment for high-risk pediatric tumors. Patients received an assigned topotecan dosage in combination with fixed doses of carboplatin and thiotepa, followed by autologous hematopoietic stem cells infusion. Topotecan dose was escalated in cohorts of four patients until the maximum tolerated dose of topotecan was defined or until accrual of 30 patients. Pharmacokinetics of topotecan were examined, and event-free survival was estimated. We describe preliminary results following treatment of 25 pediatric patients with high-risk solid tumors.

DX-8951f, a hexacyclic camptothecin analog, on a daily-times-five schedule: a phase I and pharmacokinetic study in patients with advanced solid malignancies

PURPOSE

To assess the feasibility of administering DX-8951f (exatecan mesylate), a water-soluble, camptothecin analog, as a 30-minute intravenous infusion daily for 5 days every 3 weeks, determine the maximum-tolerated dose (MTD) and pharmacokinetic (PK) behavior of DX-8951f, and seek preliminary evidence of anticancer activity.

PATIENTS AND METHODS

Patients with advanced solid malignancies were treated with escalating doses of DX-8951f. After three patients were treated at the first dose level, doses were to be escalated in increments of 100%, using a single patient at each dose level unless moderate toxicity was observed. The MTD, defined as the highest dose level at which the incidence of dose-limiting toxicity did not exceed 20%, was calculated separately for minimally pretreated (MP) and heavily pretreated (HP) patients. The PK and excretory profiles of DX-8951, the anhydrous form of DX-8951f, were also characterized.

RESULTS

Thirty-six patients were treated with 130 courses of DX-8951f at six dose levels ranging from 0.1 to 0.6 mg/m(2)/d. Brief, noncumulative neutropenia was the most common toxicity observed. Severe myelosuppression (neutropenia that was protracted and/or associated with fever and/or severe thrombocytopenia) was consistently experienced by HP and MP patients at doses exceeding 0.3 and 0.5 mg/m(2)/d, respectively. Nonhematologic toxicities (nausea, vomiting, and diarrhea) were also observed, but these effects were rarely severe. Objective antitumor activity included partial responses in one patient each with platinum-resistant extrapulmonary small-cell and fluoropyrimidine- and irinotecan-resistant colorectal carcinoma, and minor responses in patients with prostate, hepatocellular, thymic, primary peritoneal, and irinotecan-resistant colorectal carcinomas. The PKs of total DX-8951 were linear and well fit by a three-compartment model.

CONCLUSION

The recommended doses for phase II studies of DX-8951f as a 30-minute infusion daily for 5 days every 3 weeks are 0.5 and 0.3 mg/m(2)/d for MP and HP patients, respectively. The characteristics of the myelosuppressive effects of DX-8951f, paucity of severe nonhematologic toxicities, and antitumor activity against a wide range of malignancies warrant broad disease-directed evaluations of DX-8951f on this schedule.

Topotecan-based combination chemotherapy in patients with transformed chronic myelogenous leukemia and advanced myelodysplastic syndrome

BACKGROUND

Patients with transformed chronic myelogenous leukemia(CML) and advanced myelodysplastic syndrome(MDS) have poor prognosis. The aim of this study is to evaluate the feasibility of second chronic phase induction in accelerated phase(CML-AP) or blastic crisis of CML(CML-BC) and remission induction in advanced MDS by combining topoisomerase I inhibitor (topotecan) with topoisomerase II inhibitor(mitoxantrone).

METHODS

Twenty-four evaluable patients were entered on this study with a median age of 34 years. Eighteen patients with transformed CML(7 CML-AP, 11 CML-BC) and 6 patients with advanced MDS were treated. Topotecan was administered as 1.5 mg/m2/day by continuous infusion over 24 hours daily for 5 days every 4 to 8 weeks until remission. To enhance the tumoricidal effects, mitoxantrone(12 mg/m2/day, Days 1-3) was added.

RESULTS

Eight patients(33%) achieved a complete remission(CR). Four of 7 patients with CML-AP(57%), 2 of 4 patients with CML-lymphoid blastic crisis (-LBC)(50%) and 2 of 6 patients with advanced MDS(33%) had CR lasting more than 45 days(45 to 400 days). There was no CR in the patients with CML-myeloid blastic crisis(-MBC). The dose level of 1.5 mg/m2/day(7.5 mg/m2/course) of topotecan was well tolerated in all patients. Mucositis occurred in 69% of patients (severe in 5%) and diarrhea in 67%(severe in 8%). In addition, there were no new or unexpected toxicities in the patients who were treated at this dose(7.5 mg/m2/course). In patients who recovered their neutrophil count, the absolute neutrophil count(ANC) remained below 500/microL for a period of 13 to 58 days(median 21 days) and the time to ANC recovery was associated with pretreatment severity of bone marrow fibrosis(mainly CML patients). Likewise, in the patients who recovered unsupported platelets, the platelets remained below 20,000/microL for a period of 0 to 37 days (median 19 days).

CONCLUSION

The combination of topotecan-mitoxantrone has shown modest activity in CML-AP, CML-LBC and advanced MDS with acceptable toxicities.

Topotecan in squamous cell carcinoma of the cervix: A Phase II study of the Gynecologic Oncology Group

PURPOSE

The activity and toxicity of topotecan were evaluated in a multicenter Phase II study for patients with previously treated squamous cell carcinoma of the uterine cervix.

PATIENTS AND METHODS

Histologic confirmation of the primary diagnosis was required, as well as adequate performance status and vital organ function and the presence of measurable disease. Patients were allowed one prior regimen of systemic therapy, usually platinum-based. A two-stage accrual design was utilized with early stopping criteria and monitoring of toxicity. Topotecan was administered at 1.5 mg/m(2) per day for 5 consecutive days on a 21-day cycle with modifications based on hematologic toxicity.

RESULTS

Forty-five patients were entered. Two patients were ineligible (incorrect tumor type) and 2 were inevaluable (never received therapy). One additional patient was not evaluable for response (nonmeasurable disease). A median of 2 cycles was administered to each patient (range: 1-17 cycles) with grade 4 neutropenia in 68% and grade 4 thrombocytopenia in 39% of patients, but without treatment-related deaths. Nonhematologic toxicity was generally mild and not dose-limiting. The overall (complete and partial) response rate among evaluable patients with measurable disease was 12.5% with stable disease in an additional 37. 5%. Median progression-free survival was 2.1 months.

CONCLUSIONS

As a single agent topotecan shows modest antitumor activity, with manageable hematologic and nonhematologic toxicity, in patients with previously treated squamous cell carcinoma of the cervix. Further evaluation in chemotherapy-naive patients or in combination with cisplatin and/or radiation may be indicated.

Oral topoisomerase 1 inhibitors in adult patients: present and future

The renewed interest in topoisomerase 1 inhibitors, based on new insights on the mechanism of action and the development of semi-synthetic derivates of camptothecin with a more favourable toxicity profile, has led to extensive preclinical and clinical research. Significant levels of anti-tumor activity in human tumor xenografts were seen especially with prolonged duration of exposure. Since oral drug delivery is a more convenient method for prolonged drug administration, and preferred by patients, further development of oral formulations seems attractive. Common concerns in the development of oral formulations are their sometimes low oral bioavailability and the frequently large intra- and interpatient variation in systemic exposure. Efforts to improve absorption and minimize intestinal metabolism/efflux of the oral chemotherapeutic agent using new formulas might lead to better bioavailability. Pharmacokinetic and pharmacodynamic evaluations have enabled guidance in recommendations of schedules. Given the interpatient variation in exposure it is interesting to note that flat dosing of topotecan resulted in the same systemic exposure compared with the more complex dosing per body surface area. In order to diminish the interpatient variation in exposure to 9-AC a limited sampling model for oral 9-AC was developed, enabling prediction of the systemic exposure for 9-AC and optimizing treatment for any given patient. Drug sequencing plays a key role in the combination topotecan/cisplatin and might be important for combination with other classes of drugs. Therefore, forthcoming phase 1 trials on combination therapy with oral topoisomerase 1 inhibitors should include studies on sequence dependence and pharmacokinetic analyses to evaluate any mutual interaction.

Phase II evaluation of 24-h continuous infusion topotecan in recurrent, potentially platinum-sensitive ovarian cancer: A Gynecologic Oncology Group study

OBJECTIVES

The aim of this study was to develop an alternative effective and more convenient administration schedule for intravenous topotecan when used as palliative treatment in ovarian cancer.

METHODS

The Gynecologic Oncology Group conducted a Phase II trial of 24-h infusional topotecan (8.5 mg/m(2)) with treatment repeated every 3 weeks in 29 patients with platinum-sensitive recurrent ovarian cancer (prior response to platinum-based chemotherapy with a minimum treatment-free interval >/=6 months).

RESULTS

The major toxicities of therapy were grade 4 neutropenia and thrombocytopenia which developed in 86 and 14% of patients, respectively. Other severe side effects were uncommon. Only 2 partial responses (7%) were observed in the 28 patients evaluable for response.

CONCLUSIONS

Despite the relatively favorable ovarian cancer patient population treated in this trial (platinum-sensitive recurrent disease), the response rate was disappointingly low. Considering the three- to fivefold higher objective response rates observed in other trials employing topotecan in individuals with platinum-sensitive ovarian cancer utilizing a 5-day treatment program (delivered every 3 weeks), the results of the current study provide strong support for the conclusion that clinically relevant antineoplastic activity of this agent is highly schedule dependent.

Cyclophosphamide, ara-C and topotecan (CAT) for patients with refractory or relapsed acute leukemia

Topotecan is a topoisomerase I inhibitor with significant activity in patients with myelodysplastic syndrome and chronic myelomonocytic leukemia. Pre-clinical data suggest a synergistic activity with DNA damaging agents such as cyclophosphamide, where topotecan might prevent the repair of cyclophosphamide-induced DNA damage. We thus designed a combination including cyclophosphamide 500 mg/m2 every 12 hours given on days 1 to 3; topotecan 1.25 mg/m2/day by continuous infusion on days 2 to 6, and cytosine arabinoside (ara-C) 2 g/m2 over 4 hours daily for 5 days on days 2 to 6 (CAT). Sixty six (63 evaluable) patients were treated. Fifty two patients had refractory (n=12) or relapsed (n=40) acute myelogenous leukemia (AML), and eleven had acute lymphocytic leukemia (ALL) (refractory n=3, relapsed n=8); their median age was 57 years (range, 18 to 79 years). Eleven patients (17%) achieved a complete remission (CR), and two patients (3%) had a hematologic improvement (HI; met all criteria for CR except for platelets < 100x10(9)/L), for an overall response rate of 20%. Responses occurred in 12 of 52 AML patients (23%), including 10 CR (19%) and 2 HI (4%), and in 1 of 11 patients with ALL (9%). Myelosuppression was universal; there were 23 episodes of pneumonia or sepsis and 18 episodes of fever of unknown origin complicating 74 courses of CAT. Non-hematologic toxicity was mostly gastrointestinal, including nausea, vomiting, diarrhea and mucositis, but was severe in only 8%. In summary, the CAT regimen is well tolerated and has significant anti-leukemia activity which warrants further investigation.

Phase II trial of topotecan in advanced breast cancer: a Cancer and Leukemia Group B study

The topoisomerase I inhibitor topotecan had demonstrated good antitumor activity in several murine tumor systems and in human clonogenic assays by 1993. In that year, the Cancer and Leukemia Group B (CALGB) began a phase II trial to determine its activity in patients with breast cancer who had previously received one course of chemotherapy for advanced breast cancer. Between April 1993 and June 1994, 53 patients of performance status 0-2 entered the study, of whom 47 were eligible and 40 were evaluable. Topotecan was given at a dose of 1.5 mg/m2 over 30 minutes daily for 5 days every 21 days. In the absence of progression or withdrawal of consent, therapy was continued indefinitely. The median age was 58 years (range 30-79). There were no complete responses and four partial responses, resulting in an objective response rate of 10% (95% CI: 3-24%). Responses were noted in lymph nodes, liver, and skin. The median duration of response was 5 months. The median survival was 12 months. Life-threatening toxicities were almost exclusively hematologic. However, myelosuppression was not cumulative. It was concluded that topotecan has only modest activity among women with advanced breast cancer who have previously received one course of chemotherapy. Given its modest activity and predominant hematologic toxicity, it does not appear to be a promising drug for either single-agent or combination chemotherapy in the salvage setting of advanced breast cancer.

Phase I and pharmacokinetic study of a daily times 5 short intravenous infusion schedule of 9-aminocamptothecin in a colloidal dispersion formulation in patients with advanced solid tumors

PURPOSE

To determine the maximum-tolerated dose (MTD), dose-limiting toxicities (DLT), and pharmacokinetics of 9-aminocamptothecin (9-AC) in a colloidal dispersion (CD) formulation administered as a 30-minute intravenous (IV) infusion over 5 consecutive days every 3 weeks.

PATIENTS AND METHODS

Patients with solid tumors refractory to standard therapy were entered onto the study. The starting dose was 0.4 mg/m(2)/d. The MTD was assessed on the first cycle and was defined as the dose at which > or = two of three patients or > or = two of six patients experience DLT. Pharmacokinetic measurements were performed on days 1 and 5 of the first cycle and on day 4 of subsequent cycles using high-performance liquid chromatography.

RESULTS

Thirty-one patients received 104+ treatment courses at seven dose levels. The DLT was hematologic. At a dose of 1.3 mg/m(2)/d, three of six patients experienced grade 3 thrombocytopenia. Grade 4 neutropenia that lasted less than 7 days was observed in four patients. At a dose of 1.1 mg/m(2)/d, four of nine patients had grade 4 neutropenia of brief duration, which was not dose limiting. Nonhematologic toxicities were relatively mild and included nausea/vomiting, diarrhea, obstipation, mucositis, fatigue, and alopecia. Maximal plasma concentrations and area under the concentration-time curve (AUC) increased linearly with dose, but interpatient variation was wide. Lactone concentrations exceeded 10 nmol/L, the threshold for activity in preclinical tumor models, at all dose levels. Sigmoidal E(max) models could be fit to the relationship between AUC and the degree of hematologic toxicity. A partial response was observed in small-cell lung cancer.

CONCLUSION

9-AC CD administered as a 30-minute IV infusion daily times 5 every three weeks is safe and feasible. The recommended phase II dose is 1. 1 mg/m(2)/d.

Phase I and pharmacologic study of the combination of paclitaxel, cisplatin, and topotecan administered intravenously every 21 days as first-line therapy in patients with advanced ovarian cancer

PURPOSE

To evaluate the feasibility of administering topotecan in combination with paclitaxel and cisplatin without and with granulocyte colony-stimulating factor (G-CSF) support as first-line chemotherapy in women with incompletely resected stage III and stage IV ovarian carcinoma.

PATIENTS AND METHODS

Starting doses were paclitaxel 110 mg/m2 administered over 24 hours (day 1), followed by cisplatin 50 mg/m2 over 3 hours (day 2) and topotecan 0.3 mg/m2/d over 30 minutes for 5 consecutive days (days 2 to 6). Treatment was repeated every 3 weeks. After encountering dose-limiting toxicities (DLTs) without G-CSF support, the maximum-tolerated dose was defined as 5 microg/kg of G-CSF subcutaneously starting on day 6.

RESULTS

Twenty-one patients received a total of 116 courses at four different dose levels. The DLT was neutropenia. At the first dose level, all six patients experienced grade 4 myelosuppression. G-CSF support permitted further dose escalation of cisplatin and topotecan. Nonhematologic toxicities, primarily fatigue, nausea/vomiting, and neurosensory neuropathy, were observed but were generally mild. Of 15 patients assessable for response, nine had a complete response, four achieved a partial response, and two had stable disease.

CONCLUSION

Neutropenia was the DLT of this combination of paclitaxel, cisplatin, and topotecan. The recommended phase II dose is paclitaxel 110 mg/m2 (day 1), followed by cisplatin 75 mg/m2 (day 2) and topotecan 0.3 mg/m2/d (days 2 to 6) with G-CSF support repeated every 3 weeks.

Topotecan: a new topoisomerase I inhibiting antineoplastic agent

OBJECTIVE

To review the pharmacologic, pharmacokinetic, therapeutic, and safety aspects of topotecan, a new antineoplastic agent, and to assess its role in the treatment of cancer.

DATA SOURCES

MEDLINE database English language only, January 1990-March 1998; SmithKline Beecham Pharmaceuticals; published articles, books, and abstracts.

STUDY SELECTION

Studies in humans with cancer, clinical case reports, open clinical trials, and controlled clinical studies. Efficacy studies were limited primarily to trials with at least 20 evaluable patients:

DATA EXTRACTION

Relevant data were extracted only from published reports. Data were obtained from studies in both articles and abstracts. Only articles written in English were reviewed.

DATA SYNTHESIS

Topotecan is an effective second- or third-line therapy for patients with advanced ovarian cancer and is comparable to ifosfamide, liposomal doxorubicin, and paclitaxel. Activity in combination with other agents and as a first-line agent is yet to be determined. Limited data indicate activity in small-cell lung cancer, cancers of the breast and uterus, and in nonlymphocytic leukemia. The dose-limiting toxicity is myelosuppression.

CONCLUSIONS

Topotecan is an effective second-line agent for patients with unresponsive or relapsed cancer of the ovary. It appears to be similar to other active agents in patients with this disease status. Its ultimate role in ovarian cancer and other neoplasms awaits additional evaluation in combination with other agents and as first-line therapy.