Dose-escalation and pharmacodynamic study of topotecan in combination with cyclophosphamide in patients with refractory cancer

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.

A modified protocol with vincristine, topotecan, and cyclophosphamide for recurrent/progressive ewing sarcoma family tumors

PURPOSE

Topotecan has recently been used in the treatment of pediatric cancer. We evaluated our experience with the modified combination of vincristine, topotecan, and cyclophosphamide (VTC) given in 3 days, in children with recurrent Ewing sarcoma.

METHOD

Children received vincristine (1.5 mg/m(2)/1st day), cyclophosphamide (600 mg/m(2)/day × 2 days) + mesna, and topotecan (1 mg/m(2)/day × 3 days) every 21 days.

RESULT

A total of 118 courses of VTC were given to 13 patients. One patient received VTC both at first and at second relapse. Thus, 14 relapse episodes in 13 patients were evaluated. After three courses of VTC chemotherapy (CT), two achieved complete response (CR), five achieved partial response, thus an objective response was attained in 7/14 (50%) episodes. Two patients had stable disease and two patients progressed. In three episodes, CR was achieved by surgery before CT. One of them had a second relapse and attained CR with VTC. Median time from diagnosis to relapse was 23 months (5-45 months). Site of relapse was local in four patients, and metastatic in 10 episodes of nine patients. Seven patients are alive, three with no evidence of disease and four alive with disease; six have died of disease. Local treatment was used in 11 episodes. The toxicity of the VTC combination was limited mainly to the hematopoietic system.

CONCLUSION

In conclusion, the modified VTC protocol in 3 days every 3 weeks seems to be effective and tolerable in children and adolescents with recurrent/progressive Ewing sarcoma.

Multiple myeloma preparative regimens for high-dose therapy and autologous transplantation: what's new?

High-dose chemotherapy and autologous stem cell transplantation remains a standard procedure in relatively young and selected older patients with multiple myeloma. High-dose melphalan has remained the chemotherapeutic agent of choice based on earlier prospective randomized trials. Despite investigations involving different combinations of chemotherapeutics, radiation and novel agents with and without melphalan, none of these alternative preparative regimens have demonstrated superiority to high-dose melphalan used as a single agent in multiple published studies. In this article, we review the published literature regarding preparative regimens used in patients with multiple myeloma undergoing autologous stem cell transplantation.

Topotecan and ifosfamide systemic chemotherapy for CNS involvement of solid tumors

The prognosis of patients with CNS involvement of solid tumors is poor. In these patients, systemic chemotherapy has a theoretical advantage of concurrent treatment of systemic disease and reduced risk of neurotoxicity. Here, we report on the efficacy and toxicity of topotecan/ifosfamide (TOPO/IFO) combination chemotherapy in patients treated for CNS involvement of different solid malignancies. Fourteen patients with CNS manifestations (seven with brain metastases, two meningeal carcinomatosis, and five both) of solid tumors (seven with breast cancer, six lung cancer, and one unknown primary cancer) received TOPO/IFO treatment. Eleven patients each were pretreated with 1-6 systemic therapy regimens and whole-brain irradiation. Patients received a total of 34 (median 2) TOPO/IFO cycles. TOPO dosage was 3.6 mg/m(2) (1.2 mg/m(2), days 1-3) and IFO dosage 3,000 mg/m(2) (1,500 mg/m(2), days 1-2) per cycle. Of 12 patients with brain metastases, one patient had partial remission, three stable disease, two progressed, and six had no radiologic CNS response evaluation. Response of meningeal carcinomatosis was found in two and progressive disease in two (three patients not evaluated). Neurologic improvement or stabilization was observed in six of twelve evaluable patients. No systemic tumor response was seen in seven evaluated patients. Grade 3/4 toxicities in eleven evaluable patients were leukopenia (n = 9), infection (n = 6), and thrombopenia (n = 5). Median time to treatment failure was 43 days and median overall survival 107 days. Symptom control was frequently achieved with TOPO/IFO systemic chemotherapy despite a low objective response rate. The feasibility of this treatment is impaired by severe hematotoxicity.

High-Dose Topotecan, Melphalan and Cyclophosphamide (TMC) with Stem Cell Support: a New Regimen for the Treatment of Multiple Myeloma

The goal of this trial was to assess the toxicity and potential efficacy of high-dose topotecan, melphalan and cyclophosphamide as a preparative regimen for patients with multiple myeloma undergoing autologous stem cell transplantation. Eighteen patients were treated, 8 for first remission consolidation, 4 with relapse sensitive disease, 3 primary refractory and 3 relapsed refractory. The median age was 56 (38 - 65) and the median number of prior regimens was 3 (1 - 8). Patients received cyclophosphamide 1 g/m2/d on days -6, -5, -4; melphalan 70 mg/m2 on days -3, -2 and topotecan 3.0 to 3.5 mg/m2/d on days -6 to -2. Peripheral blood stem cells were infused on day 0. Toxicity (Bearman Toxicity Criteria) was mostly limited to grade 1 - 2 mucositis and grade 1 diarrhea. There were no transplant-related deaths. The overall response rate at 3 months post transplantation was 89% with 17% CR, 2 of those in refractory patients. The overall response rate in refractory patients was 67%. With a median follow up of 12.3 months, 89% of patients are alive. The TMC regimen is well tolerated and produces high response rates. Further evaluation of TMC to fully assess response and survival is ongoing.

Topotecan, cyclophosphamide, and etoposide (TCE) in the treatment of high-risk neuroblastoma. Results of a phase-II trial

PURPOSE

Relapsed high-risk neuroblastoma patients still have a poor prognosis. This phase-II trial assessed a new topotecan containing chemotherapy approach in patients with active disease.

METHODS

Chemotherapy consisted of topotecan (1.0 mg/m(2)/day 168-h continuous infusion), cyclophosphamide (100 mg/m(2)/day 1-h-infusion days 1-7 starting 6 h prior to topotecan), and etoposide (100 mg/m(2)/day 1-h-infusion days 8-10). Patients with relapsed neuroblastoma were scheduled for six cycles, untreated patients for two cycles followed by standard high-risk treatment.

RESULTS

Main toxicity observed during 153 cycles were grade 3-4 leukopenia (97% of cycles), thrombocytopenia (92%), neutropenic fever (52%), and mucositis (10%). No treatment related fatal toxicity occurred. Complete or partial response was achieved in 19 of 31 (61%) evaluable relapsed patients and 8 of 11 (72%) untreated patients.

CONCLUSIONS

The combination of topotecan, cyclophosphamide, and etoposide is tolerable and effective in relapsed and untreated neuroblastoma. Myelotoxicity is the main side effect but seems justified in view of the encouraging response rates. A randomized phase-III trial in primary disease has been commenced.

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.

Topotecan, thiotepa, and carboplatin for neuroblastoma: failure to prevent relapse in the central nervous system

We report on a three-drug myeloablative regimen designed to consolidate remission and to prevent central nervous system (CNS) relapse of high-risk neuroblastoma (NB). Sixty-six NB patients received topotecan 2 mg/m2/day, x 4 days; thiotepa 300 mg/m2/day, x 3 days; and carboplatin approximately 500 mg/m2/day, x 3 days. Post-SCT treatments included radiotherapy, immunotherapy, 13-cis-retinoic acid, +/-oral etoposide. Significant nonhematologic toxicities were mucositis and skin-related in all patients, convulsions in three patients, and cardiac failure and venocclusive disease of liver in one patient each. Grade 2 hepatotoxicity led to truncating cytoreduction in two patients; both later relapsed in brain. Among 46 patients transplanted in first complete/very good partial remission (CR/VGPR), event-free survival is 54% (s.e.+/-8%) at 36 months post-SCT; notable events were three non-NB-related deaths (adenovirus on day +9, bowel necrosis at 5 months, multiorgan failure at seven months) and four relapses in brain. Of 12 patients transplanted with evidence of NB, two became long-term event-free survivors and two relapsed in the brain. Of eight patients transplanted in second or greater CR/VGPR, one became a long-term event-free survivor and seven relapsed though not in the CNS. This regimen has manageable toxicity but does not prevent CNS relapse.

Camptothecin analogs (irinotecan or topotecan) plus high-dose cyclophosphamide as preparative regimens for antibody-based immunotherapy in resistant neuroblastoma

PURPOSE

We used high-dose cyclophosphamide plus topotecan/vincristine (CTV) or irinotecan (C/I) in patients with resistant neuroblastoma. The aim was to use a regimen with little risk to major organs to (a) achieve or consolidate remission in heavily treated patients and to (b) induce an immunological state conducive to passive immunotherapy with the murine 3F8 antibody.

EXPERIMENTAL DESIGN

CTV and C/I included cyclophosphamide 140 mg/kg ( approximately 4200 mg/m(2)). With CTV, topotecan 2 mg/m(2) was infused i.v. (30 min) on days 1-4 (total, 8 mg/m(2)), and vincristine 0.067 mg/kg was injected on day 1. With C/I, irinotecan, 50 mg/m(2) was infused i.v. (1 h) on days 1-5 (total, 250 mg/m(2)). Mesna and granulocyte colony-stimulating factor were used.

RESULTS

Twenty-nine patients received 38 courses of CTV, and 26 patients received 38 courses of C/I. All patients had previously received topotecan, a hemopoietic stem-cell transplant, and/or high-dose cyclophosphamide. CTV and C/I caused myelosuppression of comparably prolonged duration as follows: absolute neutrophil counts <500/ micro l lasted 5-12 days in patients who had not previously received transplant and 7-21 days in patients who were post-transplant. Other significant toxicities included typhlitis (two CTV-treated patients, one C/I-treated patient) and hemorrhagic cystitis (one C/I-treated patient). Major responses were seen in 4 (15%) of 26 CTV and 4 (17%) of 24 C/I-treated patients with assessable disease. Bone marrow disease resolved in 5 (28%) of 18 CTV-treated patients and in 4 (27%) of 15 C/I-treated patients. 3F8 after CTV or C/I was not blocked by neutralizing antibodies, consistent with the desired immunosuppressive effect of high-dose cyclophosphamide.

CONCLUSIONS

CTV and C/I require transfusional and antibiotic support but otherwise entail tolerable morbidity. They have modest antineuroblastoma activity in heavily treated patients and are good preparative regimens for passive immunotherapy with monoclonal antibodies.

Phase I and pharmacokinetic study of the combination of topotecan and ifosfamide administered intravenously every 3 weeks

To determine the maximum-tolerated dose (MTD), dose-limiting toxicities, and pharmacokinetics of topotecan administered as a 30-min intravenous (i.v.) infusion over 5 days in combination with a 1-h i.v. infusion of ifosfamide (IF) for 3 consecutive days every 3 weeks. Patients with advanced malignancies refractory to standard therapy were entered into the study. The starting dose of topotecan was 0.4 mg m⁻² day⁻¹ × 5 days. Ifosfamide was administered at a fixed dose of 1.2 g m⁻² day⁻¹ × 3 days. In all, 36 patients received 144 treatment courses. Owing to toxicities, the schedule of topotecan administration was reduced from 5 to 3 days. The MTD was reached at topotecan 1.2 mg m⁻² day⁻¹ × 3 days with IF 1.2 g m⁻² day⁻¹ × 3 days. Haematological toxicities were dose limiting. Neutropenia was the major toxicity. Thrombocytopenia and anaemia were rare. Nonhaematological toxicities were relatively mild. Partial responses were documented in three patients with ovarian cancer dosed below the MTD. Topotecan and IF did not appear to interact pharmacokinetically. The relationships between the exposure to topotecan lactone and total topotecan, and the decrease in absolute neutrophil count and the decrease in thrombocytes, were described with sigmoidal–E_max models. The combination of 1.0 mg m⁻² day⁻¹ topotecan administered as a 30-min i.v. infusion daily times three with 1.2 g m⁻² day⁻¹ IF administered as a 1-h i.v. infusion daily times three every 3 weeks was feasible. However, the combination schedule of topotecan and IF did result in considerable haematological toxicity and in conjunction with previously reported pronounced nonhaematological toxicities and treatment related deaths, it may be concluded that this is not a favourable combination.

Phase I study of oral cyclophosphamide and oral topotecan for children with recurrent or refractory solid tumors

BACKGROUND

To determine the maximum-tolerated duration and dose-limiting toxicity of a daily schedule of orally administered cyclophosphamide and topotecan in pediatric patients with recurrent or refractory malignant solid tumors.

METHODS

Patients received oral cyclophosphamide (50 mg/m2/dose) in the morning followed by topotecan (0.8 mg/m2/dose) 8-12 hr later for an escalating number of consecutive days (10, 14, and 17 days).

RESULTS

Seventeen pediatric patients were treated with oral cyclophosphamide and topotecan for durations of 10-17 days for a total of 58 treatment courses. Reversible hematologic toxicity (neutropenia and thrombocytopenia) was the dose-limiting toxicity. Nonhematologic toxicities of greater than grade 3 were not observed. A partial response (neuroblastoma following myeloablative chemotherapy and stem cell rescue) and prolonged stable disease (medulloblastoma) were each observed in one patient.

CONCLUSIONS

The recommended duration of therapy with a daily schedule of both oral cyclophosphamide (50 mg/m2/day) and topotecan (0.8 mg/m2/day) for previously treated pediatric patients with recurrent or refractory solid tumors is 14 consecutive days. The observed dose limiting toxicity (DLT) was reversible neutropenia. This regimen was well tolerated in heavily pretreated patients and demonstrated activity against recurrent pediatric solid tumors.

A phase II study of topotecan with vincristine and doxorubicin in children with recurrent/refractory neuroblastoma

BACKGROUND

A Phase II trial in children with advanced neuroblastoma was carried out in five Italian institutions to evaluate the antitumor activity and tolerability of topotecan followed by vincristine and doxorubicin.

METHODS

Children older than age 1 year with Stage III or Stage IV neuroblastoma, all of whom had been treated previously with chemotherapy and were diagnosed with either refractory or recurrent disease, were treated with topotecan at an intravenous dose of 1.5 mg/m(2) (the dose was 0.75 mg/m(2) for patients who were treated within 1 year of previous megatherapy) per day for 5 days followed by 48-hour intravenous infusions of 2 mg/m(2) vincristine and 45 mg/m(2) doxorubicin. Cycles of therapy were repeated every 3 weeks.

RESULTS

Twenty-five patients (2 with Stage III disease and 23 with Stage IV disease; 19 with refractory disease and 6 with recurrent disease) were treated with a total of 115 cycles. Four patients had complete responses, 12 patients had partial responses, 4 patients had minor responses or stable disease, and 5 patients had tumor progression. The overall response rate (including complete and partial responses) was 64% (95% confidence interval, 43-82%). Fifteen patients were alive at the time of the current report and were progression free at 4-16 months (median, 9 months) after the first course of this treatment. Toxicity generally was limited to the hematopoietic system. Dose-limiting toxicity was observed in only 1 patient (Grade 4 liver toxicity). There were no deaths due to infectious or toxic causes.

CONCLUSIONS

The topotecan-vincristine-doxorubicin combination was active and well tolerated in previously treated patients with advanced neuroblastoma.

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.

Growth inhibition of established B16-F10 lung metastases by sequential aerosol delivery of p53 gene and 9-nitrocamptothecin

Growth inhibition of established tumor metastases in the lungs poses a difficult challenge for most clinical settings in spite of extensive multi-modality approaches. Aerosol delivery of drugs and genes holds promise for the treatment of disseminated lung metastases, since aerosol delivery can target the lungs specifically and uniformly. We previously demonstrated that aerosol delivery of dilauroylphosphatidylcholine liposome formulation of 9-nitrocamptothecin (9NC-DLPC) inhibits B16-F10 melanoma lung metastases. Aerosol delivery of polyethleneimine-p53 DNA (PEI-p53) complexes results in a similar anti-tumor effect in the B16-F10 model. In both these previous studies, the protocols were designed to inhibit development of lung metastases. In this study we demonstrate, using the B16-F10 melanoma lung metastasis model, that sequential aerosol delivery of PEI-p53 and 9NC-DLPC acts additively to inhibit growth of established B16-F10 tumor metastases in the lungs. Mice injected with B16-F10 cells and treated with a combination of 9NC-DLPC (twice weekly) and PEI-p53 (once weekly) aerosol complexes starting on day 11 after tumor inoculation, exhibited a highly significant (P < 0.01) reduction in the number of visible tumor foci as compared with untreated mice or mice treated with either single agent alone, or with a combination of 9NC and a control plasmid. There was a highly significant reduction in the tumor burden, as well as the lung weights for the 9NC and p53 combination group (P < 0.001 as compared with other groups). Moreover, the doses of p53 gene and 9NC in the combination group were reduced at least two-fold as compared with our previous single agent studies, but still achieved significant tumor inhibition. Furthermore, the sequential aerosol delivery of p53 and 9NC lead to a 30-40% increase in the mean survival time of these mice, as compared with animals in different control groups. The data suggest that the combination of 9NC and p53 gene delivered by aerosol is an attractive strategy for growth inhibition of established tumor metastases in the lungs.

Camptothecins

Camptothecin analogues and derivatives appear to exert their antitumour activity by binding to topoisomerase I and have shown significant activity against a broad range of tumours. In general, camptothecins are not substrates for either the multidrug-resistance P-glycoprotein or the multidrug-resistance-associated protein (MRP). Because of manageable toxicity and encouraging activity against solid tumours, camptothecins offer promise in the clinical management of human tumours. This review illustrates the proposed mechanism(s) of action of camptothecins and presents a concise overview of current camptothecin therapy, including irinotecan and topotecan, and novel analogues undergoing clinical trails, such as exatecan (DX-8951f), IDEC-132 (9-aminocamptothecin), rubitecan (9-nitrocamptothecin), lurtotecan (GI-147211C), and the recently developed homocamptothecins diflomotecan (BN-80915) and BN-80927.

Phase I study of combination topotecan and carboplatin in pediatric solid tumors

PURPOSE

We conducted a phase I trial of escalating doses of topotecan (TOPO) in association with a fixed systemic exposure of carboplatin (CARBO) with or without granulocyte colony-stimulating factor (G-CSF) in children.

PATIENTS AND METHODS

Two separate cohorts of patients (pts) with solid tumors were studied: (A) pts with refractory or recurrent disease and (B) pts with no prior myelosuppressive therapy or newly diagnosed tumors for which there was no standard chemotherapy. CARBO was given on day 1 at an area under the curve of 6.5, followed by TOPO as a continuous infusion for 3 days; the starting dose of TOPO was 0.50 mg/m(2)/d. Cycles were repeated every 21 days. G-CSF was given at a dose of 5 microg/kg/d starting on day 4.

RESULTS

Forty-eight of 51 pts were assessable for toxicity. In group A, dose-limiting myelosuppression persisted despite de-escalation of TOPO to 0.3 mg/m(2)/d and use of G-CSF. In group B, the maximum-tolerated dose of TOPO was 0.5 mg/m(2)/d for 3 days, and 0.6 mg/m(2)/d for 3 days with G-CSF. No significant nonhematologic toxicities were observed. Among 46 pts assessable for response, one had complete response, five had partial response, and 18 had stable disease.

CONCLUSION

Although this combination possesses antineoplastic activity in pediatric solid tumors, hematologic toxicity precluded any meaningful TOPO dose escalation. The addition of G-CSF did not alter this. The potential for preservation of activity and diminution of toxicity with alternative sequences and schedules of administration (topoisomerase followed by alkylating or platinating agents) should be evaluated.

High-dose topotecan, melphalan, and cyclophosphamide (TMC) with stem cell support: a new regimen for the treatment of advanced ovarian cancer

OBJECTIVE

The goal of this study was to determine the optimal dose of topotecan when used in combination with high-dose melphalan and cyclophosphamide (TMC), and to assess the toxicity and efficacy of the regimen in patients with advanced ovarian cancer.

METHODS

Fifty-three patients with persistent or recurrent ovarian cancer were treated. Disease status at study entry included: platinum-sensitive recurrent disease (15 patients), platinum-resistant or refractory recurrent disease (15 patients), positive second-look surgery (16 patients), failure to achieve a primary clinical complete response (CR) (7 patients). Following stem cell mobilization and collection, patients were given cyclophosphamide 1 g/m(2)/day on Days -6, -5, -4; melphalan 70 mg/m(2)/day on Days -3, -2; and topotecan at escalating doses from 1.25 to 4.0 mg/m(2)/day on Days -6 to -2. Peripheral blood stem cells were infused on Day 0.

RESULTS

The optimal topotecan dose selected for future trials was 4.0 mg/m(2)/day x 5 days. The regimen had acceptable toxicity with no regimen-related death. Toxicity (Bearman toxicity criteria) was limited mostly to grade 1-2 mucositis and diarrhea. The overall response rate of patients with measurable or evaluable disease was 93%. Median survival has not yet been reached, but with a median follow up of 18 months (range: 11-37) 77% of patients are alive.

CONCLUSION

With a topotecan dose of 4.0 mg/m(2)/day x 5 days, the TMC regimen has acceptable toxicity and produces high response rates. In the setting of ovarian cancer, high-dose chemotherapy should be administered only as part of well-designed clinical trials. TMC should be considered a potential regimen for future randomized trials in patients with advanced ovarian cancer.

Topotecan combined with myeloablative doses of thiotepa and carboplatin for neuroblastoma, brain tumors, and other poor-risk solid tumors in children and young adults

Topotecan appears to be relatively unaffected by the most common multidrug resistance mechanisms, may potentiate cytotoxicity of alkylators, has good penetration into the central nervous system, is active against a variety of neoplasms, and has myelosuppression as its paramount toxicity. We present our experience with a myeloablative regimen that includes topotecan. Twenty-one patients with poor-prognosis tumors and intact function of key organs received topotecan 2 mg/m2 by 30-min intravenous (i.v.) infusion on days -8, -7, -6, -5, -4; thiotepa 300 mg/m2 by 3 h i.v. infusion on days -8, -7, -6; and carboplatin by 4 h i.v. infusion on days -5, -4, -3 with a daily dose derived from the pediatric Calvert formula, using a targeted area under the curve of seven mg/ml* min ( approximately 500 mg/m2/day). Stem cell rescue was on day 0. The patients were 1 to 29 (median 4) years old; 18 were in complete remission (CR) and three in partial remission (PR). Early toxicities were severe mucositis and erythema with superficial peeling in all patients and a seizure, hypertension, and renal insufficiency followed by veno-occlusive disease in one patient each. Post-transplant treatment included radiotherapy alone (four patients) or plus biological agents (11 patients with neuroblastoma). With a follow-up of 6+ to 32+ (median 11+) months, event-free survivors include 10/11 neuroblastoma patients (first CR), 4/5 brain tumor patients (second PR or CR), 1/3 patients with metastatic Ewing's sarcoma (first or second CR), and a patient transplanted for multiply recurrent immature ovarian teratoma; a patient with desmoplastic small round-cell tumor (second PR) had progressive disease at 8 months. Favorable results for disease control, manageable toxicity, and the antitumor profiles of topotecan, thiotepa, and carboplatin, support use of this three-drug regimen in the treatment of neuroblastoma and brain tumors; applicability to other tumors is still uncertain.

Cyclophosphamide plus topotecan in children with recurrent or refractory solid tumors: a Pediatric Oncology Group phase II study

PURPOSE

To determine the response rate of the combination of cyclophosphamide and topotecan in pediatric patients with recurrent or refractory malignant solid tumors.

PATIENTS AND METHODS

A total of 91 pediatric patients, 83 of whom were fully assessable for response and toxicity, received cyclophosphamide (250 mg/m2/dose) followed by topotecan (0.75 mg/m2/dose), each given as a 30-minute infusion daily for 5 days. All patients received filgrastim (5 mcg/kg) daily until the absolute neutrophil count (ANC) was > or = 1,500 microL after the time of the expected ANC nadir.

RESULTS

A total of 307 treatment courses were given to the 83 fully assessable patients. Responses (complete response plus partial response) were seen in rhabdomyosarcoma (10 of 15 patients), Ewing's sarcoma (six of 17 patients), and neuroblastoma (six of 13 patients). Partial responses were seen in two of 18 patients with osteosarcoma and in one patient with a Sertoli-Leydig cell tumor. Twenty-three patients had either minor responses (n = 6) or stable disease (n = 17); the median number of courses administered to patients with partial or complete response was six (range, two to 13 courses), and the median administered to those with stable disease was three (range, one to 11 courses). The toxicity of the combination was limited principally to the hematopoietic system. Of 307 courses, 163 (53%) were associated with grade 3 or 4 neutropenia, 84 (27%) with grade 3 or 4 anemia, and 136 (44%) with grade 3 or 4 thrombocytopenia. Despite the severe myelosuppression, only 34 (11%) of 307 courses were associated with grade 3 or 4 infection. Nonhematopoietic toxicity of grades > or = 3 was rare and consisted of nausea and vomiting (two courses), perirectal mucositis (one course), transaminase elevation (one course), and hematuria (two courses).

CONCLUSION

The combination of cyclophosphamide and topotecan is active in rhabdomyosarcoma, neuroblastoma, and Ewing's sarcoma. Stabilization of disease was seen in osteosarcoma, although objective responses were rare in this disease. The therapy can be given with acceptable hematopoietic toxicity with the use of filgrastim support.

Topoisomerase I inhibition with topotecan: pharmacologic and clinical issues

Topoisomerase I (topo-I) inhibitors are a new class of anticancer agents with a mechanism of action aimed at interrupting DNA replication in cancer cells, the result of which is cell death. Most, if not all, topo-I inhibitors are derivatives of the plant extract camptothecin. Topotecan is a derivative of camptothecin which has been structurally modified to increase water solubility. The pharmacokinetic profile of topotecan is usually characterised by a two-compartment model and is linear in the dose range of 0.5 - 3.5 mg/m(2). Current clinical trials suggest antitumour activity against a variety of human tumour types, including ovarian cancer, non-small cell lung cancer (NSCLC) and non-lymphocytic haematologic malignancies. The main dose-limiting toxicity (DLT) is non-cumulative myelosuppression. Non-haematologic toxicities are usually mild. Based on several Phase I studies, the recommended Phase II dose was 1.5 mg/m(2)/day iv. for 5 days. Current Phase I and Phase II trials are evaluating the combination of topotecan with other chemotherapeutic agents to increase the therapeutic benefits of topotecan. The DLT in these trials is mainly myelosuppression.

Topotecan (hycamptin) and topotecan-containing regimens in the treatment of hematologic malignancies

Single-agent topotecan is an active drug in chemotherapy-naive MDS and CMML and, to a lesser degree, in refractory/relapsed acute leukemias, low-/intermediate-grade lymphoma, and myeloma. Its combination with cytosine arabinoside induces complete remissions in high-risk MDS/CMML. A triple-combination regimen of cyclophosphamide, cytosine arabinoside, and topotecan (CAT) was extensively tested in refractory/relapsed as well as in untreated AML. By proving effective in inducing complete remission in newly diagnosed AML at rates comparable to those achieved by anthracycline-cytosine arabinoside regimens, for example, CAT offers a useful treatment alternative. Topotecan combined with paclitaxel is promising in low-/intermediate-grade lymphomas. The activity of topotecan justifies further evaluation of topotecan-containing combination regimens, particularly in MDS/CMML and acute leukemias.

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.

Pilot study of topotecan and high-dose cyclophosphamide for resistant pediatric solid tumors

BACKGROUND

The recommended dosages of topotecan and cyclophosphamide in combination for prior-treated patients-3.75 mg/m(2) and 1,250 mg/m(2) in children, 5 mg/m(2) and 600 mg/m(2) in adults, respectively-are well below those of each agent when used singly. We tested the hypothesis that much higher dosing would meet critical goals of salvage therapy: antitumor effect and a lack of toxicity to key organs, so as not to preclude subsequent consolidative treatments needed for cure.

PROCEDURE

Patients with resistant pediatric solid tumors received cyclophosphamide 4,200 mg/m(2) by 48 hr infusion, and topotecan 6 mg/m(2) by 72 hr infusion (HD-Cy/Topo). Mesna and granulocyte colony-stimulating factor were used. Cycles were repeated when neutrophil counts were >1,000/uL and platelet counts were >75,000/uL.

RESULTS

Twenty-eight patients, aged 2 to 33 years (median, 14), received one (n = 4), two (n = 15), or > or =3 (n = 9) cycles of HD-Cy/Topo. All patients had previously received > or =6 cycles of other therapy, high-dose alkylator-based chemotherapy, and/or etoposide- and doxorubicin-containing regimens. HD-Cy/Topo was given in an outpatient setting. Profound myelosuppression was the major toxicity, but retreatment was possible by day 28, and preliminary results with peripheral blood stem cell collections showed a sparing effect on hemopoietic stem cells. Mucositis was uncommon. After HD-Cy/Topo, cardiac, renal, hepatic, and pulmonary function remained within the normal range. Partial or minor responses were noted in neuroblastoma, desmoplastic small round-cell tumor, Ewing sarcoma, rhabdomyosarcoma, and osteosarcoma.

CONCLUSIONS

Its antitumor potential and limited toxicity make HD-Cy/Topo an attractive choice for inclusion in aggressive salvage programs aimed at achieving cures of resistant tumors. It may also merit incorporation into frontline treatment protocols.

Clinical use of topoisomerase I inhibitors in anticancer treatment

The camptothecin analogs topotecan and irinotecan have shown to be among the most effective anticancer agents and, as S-phase specific agents, their antitumor effect is maximized when they are administered in protracted schedules. The documented activity as single agents in many adult and pediatric malignancies has been followed by their use in combination with other anticancer agents. These studies have shown promising results, and have placed topotecan and irinotecan in the first line treatment for some malignancies. However, studies to better determine the optimal schedules and sequence of combinations are needed.

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.