Phase I pharmacologic study of oral topotecan and intravenous cisplatin: sequence-dependent hematologic side effects

Pharmacodynamics and pharmacokinetics of oral topotecan in patients with advanced solid tumours and impaired renal function

AIMS

The aim of the study was to determine the effect of renal impairment and prior platinum-based chemotherapy on the toxicity and pharmacokinetics of oral topotecan and to identify recommended doses for patients with renal impairment or prior platinum-based (PB) chemotherapy.

METHODS

A multicentre phase I toxicity and pharmacokinetic study of oral topotecan was conducted in patients with advanced solid tumours. Patients were grouped by normal renal function with limited or prior PB chemotherapy or impaired renal function (mild [creatinine clearance (CLcr)  = 50-79 ml min(-1) ], moderate [CLcr  = 30-49 ml min(-1) ], severe [CLcr <30 ml min(-1) ]).

RESULTS

Fifty-nine patients were evaluable. Topotecan lactone and total topotecan area under the concentration-time curve (AUC) was significantly increased in patients with moderate and severe renal impairment (109% and 174%, respectively, topotecan lactone and 148% and 298%, respectively, total topotecan). Asian patients (23 in total) had higher AUCs than non-Asian patients with the same degree of renal impairment. Thirteen dose-limiting toxicities (DLTs) were observed, which were mostly haematological. The maximum tolerated dose (MTD) was 2.3 mg m(-2) day(-1) , given on days 1 to 5 in a 21 day cycle, for patients with prior PB chemotherapy or mild renal impairment, and 1.2 mg m(-2) day(-1) for patients with moderate renal impairment (suggested dose 1.9 mg m(-2) day(-1) for non-Asians). Due to incomplete enrolment of patients with severe renal impairment, the MTD was determined as ≥ 0.6 mg m(-2) day(-1) in this cohort.

CONCLUSIONS

Oral topotecan dose adjustments are not required in patients with prior PB chemotherapy or mildly impaired renal function, but reduced doses are required for patients with moderate or severe renal impairment.

Toxicogenomics profiling of bone marrow from rats treated with topotecan in combination with oxaliplatin: a mechanistic strategy to inform combination toxicity

Combinations of anticancer agents may have synergistic anti-tumor effects, but enhanced hematological toxicity often limit their clinical use. We examined whether "microarray profiles" could be used to compare early molecular responses following a single dose of agents administered individually with that of the agents administered in a combination. We compared the mRNA responses within bone marrow of Sprague-Dawley rats after a single 30 min treatment with topotecan at 4.7 mg/kg or oxaliplatin at 15 mg/kg alone to that of sequentially administered combination therapy or vehicle control for 1, 6, and 24 h. We also examined the histopathology of the bone marrow following all treatments. Drug-related histopathological lesions were limited to bone marrow hypocellularity for animals dosed with either agent alone or in combination. Lesions had an earlier onset and higher incidence for animals given topotecan alone or in combination with oxaliplatin. Severity increased from mild to moderate when topotecan was administered prior to oxaliplatin compared with administering oxaliplatin first. Notably, six patterns of co-expressed genes were detected at the 1 h time point that indicate regulatory expression of genes that are dependent on the order of the administration. These results suggest alterations in histone biology, chromatin remodeling, DNA repair, bone regeneration, and respiratory and oxidative phosphorylation are among the prominent pathways modulated in bone marrow from animals treated with an oxaliplatin/topotecan combination. These data also demonstrate the potential for early mRNA patterns derived from target organs of toxicity to inform toxicological risk and molecular mechanisms for agents given in combination.

A novel trial of topotecan, ifosfamide, and carboplatin (TIC) in children with recurrent solid tumors

BACKGROUND

Ifosfamide, carboplatin, and etoposide (ICE) in children with refractory or recurrent solid tumors and lymphomas has resulted in good overall response rates (ORR). Etoposide, a topoisomerase-II inhibitor, however, has been associated with a significant increase in secondary leukemia. The rationale for substituting topotecan, a topoisomerase-I inhibitor, for etoposide in this regimen, a topoisomerase-II inhibitor, includes its limited toxicity profile and decreased leukemogenicity. Furthermore, topotecan in combination with both alkylators and platinating agents are additive and/or synergistic against a variety of solid tumors.

PROCEDURE

Patients with relapsed/refractory solid tumors received ifosfamide (9 g/m² ) and carboplatin (area under the curve: 3 mg/ml/min). Topotecan was also administered at 0.5 mg/m² /day × 3 days (N = 12) and in a small cohort (N = 3) at 0.75 mg/m² /day.

RESULTS

Fifteen patients were entered onto study. Two patients developed seizures/encephalitis secondary to ifosfamide. One patient had dose-limiting thrombocytopenia secondary to TIC that resolved with supportive care. Patients received a median of three cycles (1-3) of TIC. Of the 14 evaluable patients for response, 4/14 had a complete response (CR), 2/14 had a partial response (PR), and 1/14 patients had stable disease (SD). The ORR (CR + PR) was 43%.

CONCLUSION

TIC chemotherapy is feasible and tolerable in children and adolescents with refractory/recurrent solid tumors and lymphomas and results in a 43% excellent ORR in this poor-risk group of patients. A larger cohort of patients, especially in Wilms tumor and central nervous system (CNS) tumors, should be studied in the future to attempt to confirm these preliminary findings. Pediatr Blood Cancer 2015;62:274-278. © 2014 Wiley Periodicals, Inc.

Zinc (II) complex with a cationic Schiff base ligand: synthesis, characterization, and biological studies

A cationic Schiff base ligand, TSB (L) and its Zn (II) complex (1) were synthesized and characterized by using CHN, (1)H-NMR, FT-IR, UV, LC-MS, and X-ray methods. Their ability to inhibit topoisomerase I, DNA cleavage activities, and cytotoxicity were studied. X-ray diffraction study shows that the mononuclear complex 1 is four coordinated with distorted tetrahedral geometry. The singly deprotonated Schiff base ligand L acts as a bidentate ON-donor ligand. Complexation of L increases the inhibitory strength on topoisomerase I activity. Complex 1 could fully inhibit topoisomerase I activity at 250 μM, while L did not show any inhibitory effect on topoisomerase I activity. In addition, L and complex 1 could cleave pBR322 DNA in a concentration and time dependent profile. Surprisingly, L has better DNA cleavage activity than complex 1. The cleavage of DNA by complex 1 is altered in the presence of hydrogen peroxide. Furthermore, L and complex 1 are mildly cytotoxic towards human ovarian cancer A2780 and hepatocellular carcinoma HepG2.

Phase II trial of oral topotecan and intravenous carboplatin with G-CSF support in previously untreated patients with extensive stage small cell lung cancer: A North Central Cancer Treatment Group Study

OBJECTIVES

The objective of this study was to evaluate the response rate and toxicities of the combination of oral topotecan and carboplatin in patients with untreated extensive stage small cell lung cancer (ES-SCLC). Previous studies have suggested improved outcomes with a topoisomerase I inhibitor in combination with a platinum agent.

METHODS

Twenty-six patients with previously untreated, ES-SCLC were evaluable in this phase II trial. All patients received oral topotecan 2.0 mg/m per day on days 1 through 5 and carboplatin at an area under curve of 5 on day 5. Treatment was repeated every 21 days up to a total of 6 cycles. All patients received G-CSF.

RESULTS

There were no complete responses and 16 partial responses, for an overall response rate of 62% (95% CI: 41-80). Median time to progression was 6.0 months (95% CI: 4-8), with a median overall survival of 12 months (95% CI: 8-16). This study was closed to accrual early with 26 of a planned 39 patients enrolled because of grade 5 adverse events in 4 (15%) patients (3 neutropenic infections, 1 sudden cardiac death). Eighty-five percent of patients experienced grade 3 or higher hematologic events. The most common severe nonhematologic events included diarrhea, vomiting, dyspnea, hypoxia, and hypotension.

CONCLUSIONS

Although this drug regimen has activity as first-line therapy in ES-SCLC, it is associated with excessive hematologic toxicity, which occurred in spite of growth factor support. Despite promising survival estimates, this particular combination and dose level of oral topotecan and carboplatin cannot be recommended.

Semi-mechanistic description of the in-vitro antiproliferative effect of different antitumour agents

The aim of the present work was to describe the antiproliferative effect of camptothecin (CPT), topotecan (TPT) and cisplatin (CIS) in cultured cells using a semi-mechanistic pharmacodynamic approach. This effect on the growth of DHD-K12PROb cells was modelled as a function of drug concentration and time of exposure using the Gompertz framework. Models reflected two major processes: cell proliferation and cell death/degradation. Antiproliferative effect of CPT and TPT was described as inhibition of cell proliferation, while the effect of CIS was described as stimulation of cell death, including a signal transduction process, reflected as a delay in the onset of drug action. The half-life associated with such a transduction process was estimated to be approximately 27 h. Interestingly, the time profiles of the model predicted a signal transduction process that closely resembled the observed profiles of caspase-3, a protein implicated in CIS-mediated apoptosis. Therefore, the combination of a simple and sensitive design, together with an appropriated modelling strategy, allowed us to explore different mechanisms of action for antitumour agents in cultured cells and to obtain information about the dynamics of signal transduction and the potential use of biomarkers.

Phase I pharmacokinetic and pharmacodynamic study of Carboplatin and topotecan administered intravenously every 28 days to patients with malignant solid tumors

PURPOSE

Preclinical studies have shown that the combination of topotecan and carboplatin is synergistic. To evaluate the schedule dependency of this interaction, the following phase I trial was designed to determine the safety and maximum tolerated dose (MTD), pharmacokinetics, and pharmacodynamics of carboplatin and topotecan in patients with malignant solid tumors.

EXPERIMENTAL DESIGN

In part 1, patients received carboplatin on day 1 and topotecan on days 1, 2, and 3 (C-->T schedule). In part 2, topotecan was administered on days 1, 2, and 3, followed by carboplatin on day 3 (T-->C schedule). Pharmacokinetics were determined in plasma and DNA topoisomerase I catalytic activity and Pt-DNA adducts in WBC and tumor tissue.

RESULTS

Forty-one patients were included. Dose-limiting toxicities during the C-->T schedule were grade 4 thrombocytopenia and febrile neutropenia (MTD: carboplatin target area under the free carboplatin plasma concentration versus time curve, 4 min mg/mL; topotecan, 0.5 mg/m(2)/d). Dose-limiting toxicities during the T-->C schedule included grade 4 neutropenia, thrombocytopenia, neutropenic fever, and grade 4 nausea and vomiting (MTD: carboplatin target area under the free carboplatin plasma concentration versus time curve, 6 min mg/mL; topotecan, 0.9 mg/m(2)/d). One complete response and five partial responses were observed. The clearance of and exposure to carboplatin and topotecan did not depend on the sequence of drug administration. No schedule-dependent effects were seen in Pt-DNA levels and DNA topoisomerase I catalytic activity in WBC and tumor tissue. However, myelotoxicity was clearly more evident in the C-->T schedule.

CONCLUSION

The T-->C schedule was better tolerated because both hematologic and nonhematologic toxicities were milder. Other pharmacodynamic factors than the ones investigated must explain the schedule-dependent differences in toxicities.

Recent advances with topotecan in the treatment of lung cancer

Topotecan is a semisynthetic derivative of camptothecin that specifically targets topoisomerase I. It has well-established antineoplastic properties and has been successfully combined with other antineoplastic agents with activity dependent on DNA disruption, such as cisplatin and etoposide. Topotecan is indicated for the treatment of small cell lung cancer (SCLC) sensitive disease after failure of first-line chemotherapy and metastatic ovarian carcinoma after failure of initial or subsequent chemotherapy. Since the approval of topotecan for the second-line treatment of SCLC, studies have been conducted in the first-line setting. Recent studies demonstrate the utility of i.v. topotecan in combination with cisplatin for untreated SCLC. Further, an oral formulation of topotecan is currently under investigation and may provide added convenience for patients. Oral topotecan has been studied in the first- and second-line settings for both SCLC and non-small cell lung cancer (NSCLC). Three recent phase III trials have demonstrated the activity of oral topotecan. In the first study of chemotherapy-naïve patients with extensive-disease SCLC, oral topotecan plus cisplatin provided efficacy and safety similar to those of etoposide plus cisplatin. In a second study of patients with relapsed SCLC, treatment with oral topotecan showed a statistically significant and clinically meaningful longer overall survival time and improvement in dyspnea and quality of life compared with best supportive care alone in all prognostic groups. Finally, in previously treated patients with NSCLC, single-agent oral topotecan was shown to be noninferior in 1-year survival rate relative to the current standard of i.v. docetaxel. In future studies, oral topotecan will represent a good candidate for combination therapy with other i.v. or oral chemotherapy agents, monoclonal antibodies, and small molecule tyrosine kinase inhibitors.

Evaluation of Alternate Size Descriptors for Dose Calculation of Anticancer Drugs in the Obese

Purpose

Despite the rising prevalence of obesity, there is paucity of information describing how doses of anticancer drugs should be adjusted in clinical practice. Here, we assessed the pharmacokinetics of eight anticancer drugs in adults and evaluated the potential utility of alternative weight descriptors in dose calculation for the obese.

Patients and Methods

A total of 1,206 adult cancer patients were studied, of whom 162 (13.4%) were obese (body mass index ≥ 30). Pharmacokinetic parameters were calculated using noncompartmental analysis, and compared between lean (body mass index ≤ 25) and obese patients.

Results

The absolute clearance of cisplatin, paclitaxel, and troxacitabine was significantly increased in the obese (P < .023), but this was not observed for carboplatin, docetaxel, irinotecan, or topotecan (P < .17). For doxorubicin, the systemic clearance was statistically significantly reduced in obese women (P = .013), but not in obese men (P = .52). Evaluation of alternate weight descriptors for dose calculation in the obese, including predicted normal weight, lean body mass, (adjusted) ideal body weight, and the mean of ideal and actual body weight, indicated that, for most of the evaluated drugs, weight scalars used to calculate body-surface area should consider actual body weight regardless of size.

Conclusion

The results suggest that a number of widely used empiric strategies for dose adjustments in obese patients, including a priori dose reduction or dose capping, should be discouraged.

Topotecan and carboplatin in patients with platinum-sensitive recurrent ovarian cancer. Results of a multicenter NOGGO: phase I/II study

OBJECTIVE

Second-line treatment with paclitaxel and carboplatin enhances survival of women with platinum-sensitive recurrent ovarian cancer (ROC). However, because of its cumulative neurotoxicity, there is a strong demand for platinum-combinations with better therapeutic index. Because of its pharmacological properties, topotecan is a good adjunct to carboplatin in this setting, but its safety and efficacy remains to be defined.

METHODS

Patients with platinum-sensitive ROC were eligible in this multicenter phase I/II study, stratified according to treatment-free interval (TFI). Dose level 0 consisted of topotecan 1 mg/m(2)/d1-3/q21d plus carboplatin AUC5/d3/q21d. DLT was defined as grade > or =3 neutropenia or thrombocytopenia or grade > or =3 non-hematological toxicity excluding alopecia, nausea and vomiting, accompanied by a treatment delay >1 week.

RESULTS

From June 2004 to August 2005, 26 patients were enrolled, receiving a total of 145 cycles of chemotherapy. MTD was reached at topotecan 0.75 mg/m(2) and carboplatin AUC5. We observed a single grade 4 leucopenia. There were 3 (12%), 15 (58%) and 8 (31%) events of grade 3/4 hematological anaemia, leucopenia, and thrombocytopenia. Response rate was 67% (95% CI 43-85), median progression-free survival 9.5 months (95% CI 7.3-12.0), median overall survival 19.4 months (95% CI 12.3-26.9). None of the toxicity or efficacy endpoints were associated with TFI.

CONCLUSION

Topotecan and carboplatin is a well tolerated novel doublet option for women with platinum sensitive ROC. We encourage further studies on this approach, but to limit the doses of topotecan to 0.75 mg/m(2)/d1-3 and carboplatin AUC 5/d3.

Topotecan in the management of cervical cancer

Topotecan, a semisynthetic camptothecin, exerts its cytotoxic effect through inhibition of DNA topoisomerase I. Single-agent topotecan has demonstrated activity against persistent, metastatic and recurrent cancer of the uterine cervix. When combined with cisplatin in Phase II trials, further improved response rates have been reported. The cisplatin/topotecan doublet subsequently proved to be the first regimen in a series of multiple Phase III studies to demonstrate improved disease-free and overall survival in this setting compared with cisplatin alone, thus leading to its third indication by both the US FDA and the European Medicines Agency in 2006. This survival advantage was achieved at the expense of an increase in grade 3-4 hematologic toxicity; however, there was no difference in patient-reported quality of life between the cisplatin/topotecan doublet and single-agent cisplatin. This article reviews the pharmacology of topotecan and its evolution as an active agent in advanced and metastatic cervical cancer that is not amenable to cure with surgery or radiotherapy.

Phase I and pharmacologic study of sequential topotecan-carboplatin-etoposide in patients with extensive stage small cell lung cancer

The inhibition of topoisomerase I by topotecan results in a compensatory increase in topoisomerase II associated with increased in vitro sensitivity of tumors to etoposide. Maximal synergy has been observed for the sequence of topotecan followed by etoposide. Carboplatin has clinical activity when combined with either of these two agents. These interactions were the pharmacologic rationale for topotecan p.o. days 1-5, carboplatin i.v. day 6, and etoposide p.o. days 6-10. Three successive dose levels were explored: (1) topotecan 2mg/day, carboplatin AUC 5, etoposide 150 mg/day; (2) topotecan 3mg/day, carboplatin AUC 5, etoposide 150 mg/day; and (3) topotecan 3mg/day, carboplatin AUC 5, etoposide 200mg/day. Filgrastim 5 microg/kg/day was injected s.c. days 11-18. Up to 6 cycles were administered every 21 days. Eligible patients had measurable or evaluable, extensive disease, small lung cell lung cancer, no prior chemotherapy, ECOG performance status 0-2, and adequate hematologic, renal, and hepatic function. Follow-up was weekly for CBC. Tumor response was assessed after 2 and 6 cycles. Dose limiting toxicity (DLT) was defined as any of the following in cycle 1: grade 3 or 4 non-hematologic toxicity other than nausea and vomiting, grade 4 neutropenia lasting more than 3 days, neutropenic fever or sepsis, grade 4 thrombocytopenia, or failure to recover neutrophils >or=1500/microl or platelets >or=100,000/microl by day 28. Ten patients were enrolled: median age 62 (range, 50-79); female/male 4/6; and performance status 0/1/2 in 2/7/1. Three patients each were treated on dose levels 1 and 2 without DLT. The first 2 patients entered on dose level 3 had no DLT. The third patient on dose level 3 developed grade 4 neutropenia lasting more than 3 days, neutropenic fever, and grade 4 thrombocytopenia on day 15 of cycle 1. The fourth patient on dose level 3 developed grade 4 thrombocytopenia on day 18 of cycle 1. One patient received only 1 cycle and was not evaluable for response. Seven patients completed 6 cycles: 1 had a complete response and 6 achieved a partial response. The third patient on dose level 3 received 2 cycles and had stable disease, but had to be removed from protocol treatment because of grade 4 neutropenia despite dose reduction in cycle 2. The fourth patient on dose level 3 achieved a partial response, but had to be removed from protocol therapy after cycle 5 because of recurrent grade 4 thrombocytopenia. In conclusion, neutropenia and thrombocytopenia were dose-limiting. The maximum tolerated dose (MTD) is topotecan 3mg/day p.o. days 1-5, carboplatin AUC 5i.v. day 6, and etoposide 150 mg/day p.o. days 6-10 with filgrastim.

Gemcitabine and vinorelbine in recurrent advanced non-small cell lung cancer: sequence does matter

PURPOSE

Gemcitabine and vinorelbine have demonstrated clinical efficacy both as single agents and in combination in patients with metastatic non-small cell lung cancer (NSCLC). This phase II trial evaluated biweekly gemcitabine and vinorelbine in NSCLC patients who have had one prior chemotherapeutic regimen and have had disease progression.

METHODS

Gemcitabine (1,200 mg/m(2) IV over 30 min) was followed by vinorelbine (30 mg/m(2) IV over 6-10 min) on days 1 and 15 of each 28 day cycle. Chemotherapy was given for six cycles unless disease progression or unacceptable toxicity was seen.

RESULTS

From 11/1998 to 10/2000, 15 of 20 patients enrolled (6 males, 9 females) were evaluable for response and survival. Two patients had grade 4 neutropenia, and one patient had grade 4 thrombocytopenia. The only non-hematologic grade 3 toxicities were fatigue, phlebitis, and arthralgias. No objective responses were observed, but 11 patients had stable disease for a mean of 6 months. The median survival time was 9.4 months (95% CI = 4.2, 14.8), with a median time to progression of 4.2 months (95% CI = 1.9, 5.6). The 1 year survival was 47%.

CONCLUSIONS

While this schedule of gemcitabine and vinorelbine was well tolerated, it was felt to be inactive. In vitro and pharmacokinetic studies published after the completion of our trial, suggest gemcitabine followed by vinorelbine may have antagonistic effects leading to lower dose delivery of both drugs. Our study was the only study of gemcitabine and vinorelbine in second-line NSCLC in the literature without an objective response. Our study was the only second-line study that administered gemcitabine prior to vinorelbine. First-line studies in the literature that administered vinorelbine prior to gemcitabine had, on average, a 1.7 month higher median survival (10.0 vs. 8.3 mos; P value <0.001). Because of the lack of response, further studies using this drug sequence, dose, and schedule for gemcitabine and vinorelbine are not recommended.

Sequence dependence of hematologic toxicity using carboplatin and topotecan for primary therapy of advanced epithelial ovarian cancer: a phase I study of the Gynecologic Oncology Group

PURPOSE

Selection of a feasible sequence and schedule of carboplatin in combination with topotecan for evaluation in advanced epithelial ovarian cancer (EOC).

PATIENTS AND METHODS

Women with stages III-IV EOC or primary peritoneal carcinoma without prior chemotherapy were assigned to consecutive cohorts evaluating a "forward" (carboplatin day 1, topotecan days 1-3), "reverse" (carboplatin day 3, topotecan days 1-3), or "extended reverse" sequence (carboplatin day 5, topotecan days 1-5). Patients received 4 cycles carboplatin-topotecan followed by 4 cycles carboplatin-paclitaxel. Feasibility was defined according to the cumulative proportion of patients with dose-limiting events (DLEs) during the first four cycles.

RESULTS

Sixty-eight patients were enrolled across 5 cohorts. The forward sequence demonstrated unacceptable hematologic DLEs at the lowest topotecan dose (0.75 mg/m2/day x 3 days). The reverse sequence was feasible at 1.25 mg/m2/day x 3 days, with only 1/15 patients experiencing a DLE within 4 cycles, and 14/15 patients were able to receive 4 subsequent cycles of carboplatin-paclitaxel. The extended reverse sequence was associated with excessive DLEs at 1.00 mg/m2/day x 5 days. Prophylactic hematopoietic growth factors were not required.

CONCLUSION

Higher doses of topotecan could be safely administered with reduced toxicity over multiple cycles using the reverse sequence, which was selected for phase III evaluation. The relative efficacy of the forward and reverse sequence is unknown.

Evaluation of an Alternate Dosing Strategy for Cisplatin in Patients With Extreme Body Surface Area Values

Purpose

The majority of cytotoxic drugs for adults are dosed based on body surface area (BSA), aiming to reduce interpatient variability in drug exposure. We prospectively studied the usefulness of BSA-based dosing of cisplatin in patients at extremes of BSA values.

Patients and Methods

Patients were randomly assigned to receive a fixed dose of cisplatin in course 1, and a BSA-adjusted dose in course 2, or vice versa. The fixed dose was based on the average BSA for males and females, while extremes were set at BSA values exceeding the average ± 1 standard deviation. Subsequently, we retrospectively analyzed data from a normal population.

Results

In 25 patients assessable for both courses, the use of a fixed dose of cisplatin resulted in reduced exposure to unbound platinum in patients at the upper extremes of BSA (P = .003) and higher exposures in patients at the lower extremes (P = .009), as compared with exposures following the BSA-adjusted dose. Although clearance was related to BSA (R2 = 0.44; P < .001), only a small reduction in interpatient variability in clearance after correction for BSA was achieved (20.8% v 17.1%). In the retrospective analysis, compared with the average patient, the clearance of unbound platinum in patients with a BSA value ≤ 1.65 m2 was 16% slower (P < .001), while an 18% faster clearance (P < .001) was observed in patients with a BSA value ≥ 2.05 m2.

Conclusion

Unless better predictors for platinum clearance are identified, fixed-dose regimens per BSA cluster (≤ 1.65 m2; 1.66 m2 to 2.04 m2; ≥ 2.05 m2) are recommended.

Phase I and Pharmacokinetic Study of Sequences of the Rebeccamycin Analogue NSC 655649 and Cisplatin in Patients with Advanced Solid Tumors

PURPOSE

To evaluate the feasibility of administering NSC 655649, a water-soluble rebeccamycin analogue that inhibits both topoisomerases I and II, in combination with cisplatin (CDDP) in adults with solid malignancies. Major toxicologic and pharmacologic differences between the two sequences of drug administration were also assessed.

EXPERIMENTAL DESIGN

NSC 655649 was administered as a 60-minute i.v. infusion; CDDP was given i.v. before or after NSC 655649 on day 1. Each patient was treated with alternating drug sequences every 3 weeks; doses of each drug were escalated in separate cohorts of new patients. Sequential dose escalation of NSC 655649 or CDDP resulted in three dosage permutations of NSC 655649/CDDP: 440/50, 550/50, and 440/75 mg/m2. After the maximum tolerated dose level was determined, the feasibility of using granulocyte colony-stimulating factor to permit further dose escalation was explored.

RESULTS

Twenty patients were treated with 70 courses of NSC 655649/CDDP. Myelosuppression was the principal toxicity. The incidence of severe neutropenia, often associated with severe thrombocytopenia, was unacceptably high in minimally pretreated patients at the NSC 655649/CDDP dose level of 550/50 mg/m2 without and with granulocyte colony-stimulating factor. Major pharmacokinetic interactions between NSC 655649 and CDDP were not apparent. No relevant sequence-dependent differences in toxicity or pharmacokinetic variables occurred. Three patients had partial responses.

CONCLUSIONS

NSC 655649 and CDDP were well tolerated by minimally pretreated subjects at 440 and 50 mg/m2, respectively. Neither pharmacokinetic interactions between the agents nor sequence-dependent toxicologic or pharmacokinetic effects were apparent. The tolerance and preliminary activity observed with this combination suggest that disease-directed evaluations of the regimen are warranted.

Phase I trial of intravenous cisplatin-topotecan chemotherapy for three consecutive days in patients with advanced solid tumors: parallel topotecan escalation in two fixed platinum dosing schemes

PURPOSE

We performed a phase I study of two fixed dosing schemes of cisplatin, a DNA cross-linker, with intravenous escalating topotecan, a DNA-topoisomerase I inhibitor.

EXPERIMENTAL DESIGN

40 patients with advanced solid tumors received intravenous cisplatin at a fixed dose of either 25 mg/m2 (schedule A) or 20 mg/m2 (schedule B) daily for 3 days with standard hydration. Topotecan escalation proceeded in 0.75, 0.90, 1.0, 1.15 mg/m2 cohorts in schedule A and 1.0, 1.1, 1.2, 1.3 mg/m2 cohorts in schedule B, administered intravenously at the end of cisplatin infusion daily for 3 days, repeated every 3 weeks. Dose-limiting toxicity (DLT) consisted of protracted grade IV neutropenia, febrile neutropenia, grade IV thrombocytopenia and any grade III/IV non-hematological toxicity. Epoetin and granulocyte colony-stimulating factor support was allowed on severe myeloablation. Endpoints were the identification of maximal tolerated dose (MTD), DLT and other toxicity.

RESULTS

The MTD was reached in cohort 25/1.15 mg/m2 in schedule A and 20/1.2 mg/m2 in schedule B. All DLT seen consisted of three episodes of febrile neutropenia and two of grade IV thrombocytopenia in schedule A, with three episodes of febrile neutropenia and one of protracted neutropenia in schedule B. Myelosuppression was substantial in all cohorts despite granulocyte colony-stimulating factor and epoetin support, peaked on the third week of treatment and resulted in administration of chemotherapy at a median of every 4 weeks. Non-hematologic toxicity was mild. The response rate was 51% with seven complete responses occurring in patients with ovarian cancer, small cell and non-small cell lung cancer and cancer of unknown primary. The recommended dose was 20/ 1.1 mg/m2 for cisplatin and topotecan on schedule B, as the number of responses and administered topotecan dose were higher in schedule B recommended dose with lower cisplatin dose, minimizing problems of nephrotoxicity and vomiting.

CONCLUSIONS

The schedule B daily cisplatin-topotecan x 3 combination with secondary cytokine support is associated with promising activity and schedule convenience. However, substantial myelosuppression undermines its applicability in the palliative setting, stressing the need for less toxic regimens.

A phase I and pharmacodynamic study of fludarabine, carboplatin, and topotecan in patients with relapsed, refractory, or high-risk acute leukemia

PURPOSE

A novel regimen designed to maximize antileukemia activity of carboplatin through inhibiting repair of platinum-DNA adducts was conducted in poor prognosis, acute leukemia patients.

EXPERIMENTAL DESIGN

Patients received fludarabine (10 to 15 mg/m(2) x 5 days), carboplatin (area under the curve 10 to 12 by continuous infusion over 5 days), followed by escalated doses of topotecan infused over 72 hours (fludarabine, carboplatin, topotecan regimen). Twenty-eight patients had acute myelogenous leukemia (7 untreated secondary acute myelogenous leukemia, 11 in first relapse, and 10 in second relapse or refractory), 1 patient had refractory/relapsed acute lymphoblastic leukemia, and 2 patients had untreated chronic myelogenous leukemia blast crisis. Six patients had failed an autologous stem cell transplant. Patients ranged from 19 to 76 (median 54) years. Measurement of platinum-DNA adducts were done in serial bone marrow specimens.

RESULTS

Fifteen of 31 patients achieved bone marrow aplasia. Clinical responses included 2 complete response, 4 complete response with persistent thrombocytopenia, and 2 partial response. Prolonged myelosuppression was observed with median time to blood neutrophils >/=200/microl of 28 (0 to 43) days and time to platelets >/=20,000/microl (untransfused) of 40 (24 to 120) days. Grade 3 or greater infections occurred in all of the patients, and there were 2 infection-related deaths. The nonhematologic toxicity profile was acceptable. Five patients subsequently received allografts without early transplant-related mortality. Maximum tolerated dose of fludarabine, carboplatin, topotecan regimen was fludarabine 15 mg/m(2) x 5, carboplatin area under the curve 12, and topotecan 2.55 mg/m(2) over 72 hours. An increase in bone marrow, platinum-DNA adduct formation between the end of carboplatin infusion and 48 hours after the infusion correlated with bone marrow response.

CONCLUSIONS

Fludarabine, carboplatin, topotecan regimen is a promising treatment based on potential pharmacodynamic interactions, which merits additional study in poor prognosis, acute leukemia patients.

Factors affecting pharmacokinetic variability of oral topotecan: a population analysis

The aim of this study was to characterise the pharmacokinetics of the anticancer agent topotecan, and explore the influence of patient covariates and interoccasion variability on drug disposition. Data were obtained from 190 patients who received the drug as a 30-min infusion (N=72) or orally (N=118). The population model was built with the use of NONMEM to identify candidate covariates, and obtain models for clearance (CL) and volume of distribution. The final models were based on first-order absorption with lag-time (oral data), and a two-compartment model with linear elimination from the central compartment. The Cockcroft–Gault creatinine clearance (CrCl) and WHO performance status (PS) were the only significant covariates: CL=(12.8+2.1 × CrCl) × (1−0.12 × PS). For the volume of distribution, a correlation was found between body weight and the central volume (V1)=0.58 × body weight. Based on the structural models, a limited-sampling strategy was developed with minor bias and good precision that can be applied a posteriori using timed samples obtained at 1.5, and 6 h after the administration of topotecan. In conclusion, a population pharmacokinetic model for topotecan has been developed that incorporates measures of renal function and PS to predict CL. In combination with drug monitoring, the limited sampling strategy allows individualised treatment for patients receiving oral topotecan.

Carboplatin plus paclitaxel combination chemotherapy: impact of sequence of drug administration on treatment-induced neutropenia

OBJECTIVE

While the importance of the sequence of administration of cisplatin and paclitaxel on the degree of observed neutropenia has been documented, there is limited information available in the oncology literature to determine whether there exists sequence-dependent toxicity for the combination of carboplatin plus paclitaxel.

METHODS

Patients with advanced gynecologic malignancies were randomized to receive either carboplatin (AUC 6), followed by paclitaxel (175 mg/m(2) over 3 h) (C-P), or the same doses of the agents delivered in the opposite sequence (P-C). The primary endpoint was the degree of neutropenia experienced during the initial treatment course.

RESULTS

A total of 40 patients (median age: 63) entered this trial, of whom 27 had complete pretreatment and nadir counts available for course 1 and 24 for both course 1 and course 2. By random chance, patients initially receiving P-C began therapy with a higher baseline ANC than those treated with C-P. During course 1, the P-C population was noted to have a greater reduction, from baseline, in ANC (P = 0.02), but no difference in absolute nadir counts (ignoring the baseline value) (P = 0.64). There was no difference between P-C, followed by C-P, versus C-P, followed by P-C in the severity of neutropenia experienced during course 2 (P = 0.38).

CONCLUSIONS

The sequence of carboplatin/paclitaxel administration does not exert a significant influence on the level of observed neutropenia. This finding leads to the suggestion that the sequence of drug delivery can be modified, as necessary, to satisfy unique requirements of individual patients and to establish the optimal drug delivery strategy of an innovative investigational treatment regimen.

Influence of the cisplatin hydration schedule on topotecan pharmacokinetics

The study described here was designed to investigate the influence of the hydration schedule of cisplatin on the pharmacokinetics of topotecan. To test this hypothesis, 13 adult cancer patients were treated with intravenous (i.v.) cisplatin followed by i.v. topotecan for 5 days every 3 weeks using a short hydration schedule (SHS) for cisplatin in the first course and a hyper-hydration schedule (HHS) in the second course or vice versa. Topotecan pharmacokinetic analysis was performed in plasma, whole blood and red blood cells in both courses on days 1, 2 and 5. 11 patients received both courses and were pharmacokinetically evaluable. No significant differences between the two studied schedules were noted in the clearances of topotecan on day 1 in the different matrices. However, in both hydration schedules, on average, slightly lower topotecan clearances were observed on both days 2 and 5 compared with day 1 in all of the matrices, while no differences were noted between days 2 and 5. This alteration was independent of the schedule used and was less pronounced than that which has been initially reported for SHS and, overall, will not have clinical consequences.

Red blood cells: a neglected compartment in topotecan pharmacokinetic analysis

Previously, a gender dependency of topotecan was found in the pharmacokinetics in the plasma compartment. Here, we prospectively studied the red blood cell (RBC) partitioning of topotecan and evaluated its consequences for overall drug disposition. Blood samples were obtained from 12 patients receiving cisplatin followed by i.v. topotecan. Topotecan pharmacokinetic analysis was performed in whole blood, plasma and RBCs. Significantly slower clearance was noted in females (n=7) compared to males (n=5) for lactone and total topotecan in plasma (p<0.0001), and for total drug in RBCs (p=0.027), but not in whole blood. In addition, no gender-dependent differences were observed in the terminal half-lives of topotecan in any of the compartments. The area under the curve ratios for RBC total to plasma lactone were 2.53+/-0.0640 and 2.13+/-0.442 in males and females, respectively. Hence, topotecan displays preferential affinity for RBCs compared to plasma, although these cells do not act as a depot in which drug accumulates over time. RBCs thus play a principal role in the distribution kinetics of topotecan and have a major impact on its plasma pharmacokinetics. The data warrant a change from current practice in pharmacokinetic studies with this agent and provide further evidence that, in general, the choice of the appropriate assay matrix should be rationally based.

Role of body surface area in dosing of investigational anticancer agents in adults, 1991-2001

The prescribed dose of anticancer agents is most commonly calculated using body surface area as the only independent variable, and it has been shown that this approach still results in large interpatient variability in drug exposure. Here, we retrospectively assessed the pharmacokinetics of 33 investigational agents tested in phase I trials from 1991 through 2001, as a function of body surface area in 1650 adult cancer patients. Twelve of the drugs were administered orally, 19 were administered intravenously, and two were administered by both routes. Body surface area-based dosing was statistically significantly associated with a reduction in interpatient variability in drug clearance for only five of the 33 agents: docosahexaenoic acid (DHA)-paclitaxel, 5-fluorouracil/eniluracil, paclitaxel, temozolomide, and troxacitabine. These results do not support the use of body surface area in dose calculations and suggest that alternate dosing strategies should be evaluated. We conclude that body surface area should not be used to determine starting doses of investigational agents in future phase I studies.

DNA-based drug interactions of cisplatin

The interactions of cisplatin with other anti-cancer agents on the DNA level have been studied extensively in pre-clinical experiments. In general, combination of cisplatin with an antimetabolite, taxane, or topoisomerase inhibitor, can result in a modulation of platinum pharmacology on the DNA, for example, enhanced retention of the platinum-DNA adducts. These interactions are mostly sequence and cell type dependent. In cell line models, antimetabolites can enhance the number of platinum-DNA adducts, probably by inhibition of DNA repair pathways. However, in clinical trials, the opposite effect has been observed, with a reduction of these adducts upon combined treatment. For the taxanes it has been shown that they can inhibit the formation of platinum-DNA adducts, whereas topoisomerase I inhibitors increase the number of adducts, resulting in strong synergistic cytotoxicity. For this last interaction a mechanistic model has recently been proposed, in which the topoisomerase I enzyme directly binds to the platinum-DNA adduct. Thereafter, the topoisomerase I inhibitor binds to this complex, which yields large stabilised lesions to the DNA that are probably difficult to repair. Ongoing studies will proceed to elucidate the exact mechanism underlying the interactions between cisplatin and other anti-neoplastic agents on the DNA level. Such increased understanding might help in designing new and more effective treatment regimens for cancer. In this paper, we review the pre-clinical and clinical studies investigating the observed interactions between cisplatin, the antimetabolites, taxanes, and topoisomerase inhibitors on the DNA level.

Dose-dense cisplatin/paclitaxel. a well-tolerated and highly effective chemotherapeutic regimen in patients with advanced ovarian cancer

A randomised phase I/II trial with weekly cisplatin 70 mg/m(2) (days 1, 8, 15, 29, 36, 43) in combination with escalating doses of paclitaxel either 4-weekly or weekly was conducted in 49 patients with ovarian cancer; patients were chemotherapy-nai;ve or had a first relapse after platinum-based chemotherapy. Paclitaxel could be safely escalated to 225 mg/m(2) 4-weekly or 100 mg/m(2) weekly, with fatigue as the major adverse event. Myelosuppression, renal toxicity and neurotoxicity were mild to moderate. Pharmacokinetic analysis showed an approximately 2-fold reduction of DNA-adduct formation in leucocytes compared with cisplatin without paclitaxel. No pharmacokinetic interaction was found between paclitaxel and cisplatin. After (re-)induction, additional chemotherapy consisted of conventional paclitaxel/cisplatin, paclitaxel/carboplatin, paclitaxel single agent or carboplatin/cyclophosphamide. The overall response rate was 94% in 17 evaluable chemotherapy-nai;ve patients and 84% in 25 patients with recurrent disease. Median progression-free survival (PFS) was 17 months (chemotherapy-nai;ve: 23 months, recurrent: 11 months) and median overall survival was 41 months (chemotherapy-nai;ve: 48 months, recurrent: 24 months). In conclusion, both cisplatin/paclitaxel regimens showed excellent activity with manageable toxicity in patients with advanced ovarian cancer.

Phase II trial of topotecan and cisplatin in persistent or recurrent squamous and nonsquamous carcinomas of the cervix

OBJECTIVE

Cisplatin is a standard treatment in advanced, recurrent cervical cancer. Because topotecan is an established treatment in gynecologic malignancies such as ovarian cancer and exhibits nonoverlapping toxicity with cisplatin, a phase II trial was conducted to evaluate the tolerability and antitumor activity of a cisplatin/topotecan doublet in persistent or recurrent cervical cancer patients.

METHODS

Patients with bidimensionally measurable persistent or recurrent squamous cell and non squamous cell cervical cancer and adequate bone marrow were enrolled. Patients received 50 mg/m(2) of cisplatin intravenously over 1 h on Day 1 and 0.75 mg/m(2) of topotecan intravenously over 30 min on Days 1, 2, and 3 of 21-day cycles for six cycles or until disease progression. Tumor response and regimen toxicity were assessed using established Gynecologic Oncology Group criteria.

RESULTS

Thirty-two of 35 enrolled patients were evaluable for toxicity and tumor response. All but 2 evaluable patients had received previous radiotherapy. No patient received prior chemotherapy. The cisplatin/topotecan doublet was well tolerated, with 77 and 78% of courses given without interruption or delay and at full doses, respectively. As anticipated, the most common toxicity was hematologic, with grade 3/4 neutropenia and thrombocytopenia reported in 30 and 10% of cycles, respectively. The overall response rate was 28% (9/32), with 3 complete and 6 partial responses. The antitumor response in nonirradiated fields (30%) was similar to the response observed in previously irradiated fields (33%), suggesting good drug penetration. Median duration of response was 5 months (range, 2 to 15+ months). An additional 9 (28%) patients achieved stable disease. Median survival was 10 months, with 3 patients in lasting remission.

CONCLUSIONS

These results demonstrate that the cisplatin/topotecan combination is safe, well tolerated, and active in persistent or recurrent cervical cancer patients. A phase III, multicenter trial is under way (cisplatin/topotecan versus cisplatin) based on these favorable results to confirm the safety and efficacy profile in this patient population.

Developmental chemotherapy in advanced ovarian cancer: incorporation of newer cytotoxic agents in a phase III randomized trial of the Gynecologic Oncology Group (GOG-0182)

Despite improvements in median and overall survival using a combination of platinum and paclitaxel, long-term survival rates for patients with advanced epithelial ovarian carcinoma (EOC) remain disappointing, and the development of more effective primary therapy remains a priority. In particular, several interesting chemotherapy agents have demonstrated activity individually in patients with recurrent EOC. Among these are gemcitabine, topotecan, liposomal doxorubicin, and prolonged oral etoposide. Preclinical models have suggested an advantage for combinations of these agents with platinum, which has been attributed to inhibition of DNA synthetic pathways involved in the repair of platinum-DNA adducts. However, efforts to develop multidrug combinations with platinum and paclitaxel have encountered substantial bone marrow toxicity, prompting exploration of alternative schedules and sequences of drug administration. In this regard, the Gynecologic Oncology Group (GOG) and other organizations have conducted a series of phase I pilot studies in previously untreated patients to define combinations that are suitable for group-wide phase III trials. With international collaboration, GOG has launched a five-arm trial (GOG-0182) that will compare these combinations against carboplatin-paclitaxel. The selection of candidate regimens for this trial illustrates the challenges of drug development in EOC.

Determination of topotecan in human whole blood and unwashed erythrocytes by high-performance liquid chromatography

A reversed-phase HPLC method for the quantitative determination of total topotecan in human whole blood and unwashed erythrocytes has been developed and validated in terms of sensitivity, specificity, precision and accuracy. Linear calibration curves were constructed in the range of 0.20 to 50.0 ng/ml. The sample pre-treatment for whole blood involved a two-step extraction with methanol and perchloric acid. Prior to extraction, erythrocytes were separated from other blood components by centrifugation in MESED instruments. Separations were achieved on an Inertsil ODS-80A analytical column (150x4.6 mm, 5 microm particle size), eluted at 50 degrees C and a flow-rate of 1.00 ml/min, with a mixture of 100 mM ammonium acetate (pH 6.0)-tetrahydrofuran (94.6:5.4, v/v). Fluorescence detection was performed using excitation and emission wavelengths of 381 and 525 nm, respectively. With the applied method, 80% of topotecan was extracted out of whole blood. The lower limit of quantitation in whole blood was established at 0.20 ng/ml with within-run and between-run precisions, respectively, ranging from 1.7 to 9.3% and 1.5-6.1%, while the accuracy ranged from 100 to 113%. The described method will be used in clinical studies to explore the role of erythrocytes in the overall kinetic behavior of topotecan.

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.

Modulation of cisplatin pharmacodynamics by Cremophor EL: experimental and clinical studies

The paclitaxel vehicle Cremophor EL (CrEL) has been shown to selectively inhibit the accumulation of cisplatin in peripheral blood leucocytes, but not in tumour cells in vitro, and we hypothesised that this phenomenon is responsible for the improvement of the therapeutic index of cisplatin observed in combination studies with paclitaxel. Here, we report on studies assessing the interaction between CrEL and cisplatin in a murine model, and involving the potential clinical applicability of CrEL as a protector for cisplatin-associated haematological side-effects. In mice, CrEL (0.17 ml/kg, intravenous (i.v.)) given in combination with cisplatin (10 mg/kg, intraperitoneal (i.p.)) did not change the pharmacokinetics of cisplatin. Cisplatin-induced haematological toxicity, expressed as white blood cells (WBC) at nadir, was significantly reduced by CrEL from 5.05+/-0.95 to 6.50+/-1.31 x 10(9)/l (P=0.0009). Data obtained from cancer patients treated with cisplatin (70 mg/m(2), 3-h i.v.) and topotecan (0.45 or 0.60 mg/m(2)/day x 2) preceded by CrEL (12 ml, 3-h i.v.) (n=6) or without CrEL (n=10) similarly indicated significant differences in the percent decrease in WBC between the groups (46.5+/-18.7 versus 67.2+/-15.0%; P=0.029). Likewise, the percent decrease in platelet count was significantly greater in the absence of CrEL (23.9+/-5.38 versus 73.3+/-15.5%; P=0.0003). Pharmacokinetic parameters of unbound and total cisplatin and of topotecan lactone and total drug were not significantly different from historic control values (P>or=0.245). Overall, this study provides further evidence on the important role of CrEL in the pharmacological and toxicological profile of cisplatin, and implies that reformulation of cisplatin with CrEL for systemic treatment might achieve an improvement of its therapeutic index, particularly in the setting of a weekly dose-dense concept.

Topoisomerase I inhibitors combination chemotherapy in non-small cell lung cancer

In the last years, the main topoisomerase I inhibitors (TP1-I) (i.e. topotecan and irinotecan) have been used in combination chemotherapy in non-small cell lung cancer. Several drugs (also alternative to cisplatin) have been used in combination with TP1-I, but to date the higher remission rate obtained with combinations is not translated into a more prolonged survival in comparison with TP1-I given alone. On the other hand, the toxicity of TP1-I combinations is greater than those of TP1-I used alone. The superior efficacy of combinations versus TP1-I used alone remains an open question. Furthermore, the best schedule for TP1-I has not been completely elucidated. Randomised studies are few (only two phase III trials) and only controlled studies will be able to clarify the best TP1-I combination regimen.

A phase I/II study of topotecan in combination with carboplatin in recurrent epithelial ovarian cancer

OBJECTIVE

The purpose of this study was to define the maximum tolerated dose (MTD) of topotecan given as escalating doses combined to a fixed dosage of carboplatin in late relapsing ovarian carcinomas.

METHODS

Women with relapsing ovarian cancer more than 6 months after first-line treatment were eligible for the study. In the first phase of the trial, patients were allocated to escalating topotecan doses with a carboplatin fixed dose (AUC 5, according to Cockcroft's formula). If no "severe" adverse event occurred in 1 or more of the patients, the topotecan dose was increased. The starting dose of topotecan was 0.50 mg/m(2)/day, for 3 consecutive days, and the dose step was of 0.25 mg/m(2)/day, till 1.5 mg/m(2)/day. The study progressed then in a phase II trial.

RESULTS

A total of 39 patients entered the trial. Twenty took part in the escalating topotecan dose phase (4 per dose level, 0.50, 0.75, 1, 1.25, and 1.50 mg/m(2)/day) and 19 in the phase II. No severe adverse event was observed in the phase I of the trial, so the MTD was not reached. In the phase II trial topotecan was given to 1 mg/m(2)/day. Overall grade 3-4 neutropenia, lasting 7 days or less, was observed in 58.9% (23 patients). Thrombocytopenia occurred in 30.8% (12 patients) and grade 3 anemia in 25.6% (10 patients) of subjects. No life-threatening event occurred. Platelets or red blood cell transfusions were given in three cases (7.8%).

CONCLUSIONS

This daily-times-3-day schedule of topotecan in combination with carboplatin is safe.

Dose and schedule-finding study of oral topotecan and weekly cisplatin in patients with recurrent ovarian cancer

Both weekly cisplatin chemotherapy and single agent topotecan have proven to be effective in recurrent ovarian cancer. Preclinical data show synergism between cisplatin and topotecan. Side effects for this combination are drug sequence dependent and predominantly haematologic. Since preclinical data suggest that Cremophor EL (CrEL), the formulation vehicle of paclitaxel, has a protective effect on haematological toxicity of cisplatin, CrEL was added to the combination cisplatin and topotecan. In this phase I study, escalating doses of oral topotecan administered on day 1, 2, 8, 9, 15, 16, 29, 30, 36, 37, 43, 44 were combined with weekly cisplatin 70 mg m(-2) d(-1) on day 1, 8, 15, 29, 36, 43 (scheme A) or with the presumably less myelotoxic sequence weekly cisplatin day 2, 9, 16, 30, 37, 44 (scheme B). In scheme C, CrEL 12 ml was administered prior to cisplatin in the sequence of Scheme A. 18 patients have received a total of 85 courses. In scheme A 4/10 patients, all treated with topotecan 0.45 mg m(-2) d(-1), experienced DLT: 1 patient had vomiting grade 4, 1 patient had grade 4 neutropenia >5 days, 1 patient had >2 weeks delay due to thrombocytopenia and 1 patient due to neutropenia. Both patients in scheme B (topotecan 0.45 mg m(-2) d(-1)) had DLT due to a delay > 2 weeks because of prolonged haematological toxicity. No DLT was observed in the first 3 patients in scheme C (topotecan 0.45 mg m(-2) d(-1)). However, 2 out of 3 patients treated at dose level topotecan 0.60 mg m(-2)d(-1) in scheme C experienced DLT due to >2 weeks delay because of persistent thrombocytopenia or neutropenia. We conclude that there is a modest clinical effect of CrEL on haematological toxicity for this cisplatin-based combination regimen, which seems to reduce these side effects but does not really enable an increase of the oral topotecan dose.

Body-surface area-based dosing does not increase accuracy of predicting cisplatin exposure

PURPOSE

Most anticancer drugs are dosed based on body-surface area (BSA) to reduce interindividual variability of drug effects. We evaluated the relevance of this concept for cisplatin by analyzing cisplatin pharmacokinetics obtained in prospective studies in a large patient population.

PATIENTS AND METHODS

Data were obtained from 268 adult patients (163 males/105 females; median age, 54 years [range, 21 to 74 years]) with advanced solid tumors treated in phase I/II trials with cisplatin monotherapy or combination chemotherapy with etoposide, irinotecan, topotecan, or docetaxel. Cisplatin was administered either weekly (n = 93) or once every 3 weeks (n = 175) at dose levels of 50 to 100 mg/m(2) (3-hour infusion). Analysis of 485 complete courses was based on measurement of total and non-protein-bound cisplatin in plasma by atomic absorption spectrometry.

RESULTS

No pharmacokinetic interaction was found between cisplatin and the anticancer drugs used in combination therapies. A linear correlation was observed between area under the curves of unbound and total cisplatin (r = 0.63). The mean plasma clearance of unbound cisplatin (CL(free)) was 57.1 +/- 14.7 L/h (range, 31.0 to 116 L/h), with an interpatient variability of 25.6%. BSA varied between 1.43 and 2.40 m(2) (mean, 1.86 +/- 0.19 m(2)), with an interpatient variability of 10.4%. When CL(free) was corrected for BSA, interindividual variability remained in the same order (23.6 v 25.6%). Only a weak correlation was found between CL(free) and BSA (r = 0.42). Intrapatient variability in CL(free), calculated from 90 patients was 12.1% +/- 7.8% (range, 0.30% to 32.7%).

CONCLUSION

In view of the high interpatient variability in CL(free) relative to variation in observed BSA, no rationale for continuing BSA-based dosing was found. We recommend fixed-dosing regimens for cisplatin.

Phase I and pharmacologic study of sequential topotecan, carboplatin, and etoposide

Inhibition of topoisomerase I by topotecan results in a compensatory increase in topoisomerase II levels associated with increased in vitro sensitivity of tumors to etoposide. Maximum synergy has been observed for the sequence of topotecan followed by etoposide. This is the pharmacologic rationale for the sequence of topotecan 0.4 mg/m(2) per day for 7 days continuous i.v. infusion, carboplatin i.v. on day 8, and etoposide 50 mg per day p.o. days 9 through 20. The carboplatin dosage was escalated from an AUC of 4 to 5 to 6 (Calvert formula). Up to six treatment cycles were administered at 28-day intervals. Eligible patients had metastatic non-small cell lung cancer (NSCLC) or extensive disease small lung cell lung cancer (SCLC), no prior chemotherapy, performance status 0-2, and adequate organ function. Follow-up was twice weekly in the first cycle for CBC and for topotecan and etoposide concentrations. Follow-up, thereafter, was weekly. Tumor response was assessed after two and six cycles and then as clinically indicated. At carboplatin AUCs of 4 and 5, no NCI grade 4 toxicity was observed in cycle 1 in cohorts of three patients each. At the AUC of 5, two patients experienced dose-limiting events after cycle 3, one grade 4 neutropenia lasting >3 days (no fever) and one failure to recover an absolute neutrophil count >1500/microl by day 35. This was, therefore, deemed the maximal tolerable dose. Number of treatment cycles per patient ranged between 1 and 6, and three patients completed six cycles. All patients were male, age 47-71, with NSCLC in one and SCLC in six. The patient with NSCLC had progressive disease after one cycle. One complete and three partial responses were observed in five patients with SCLC. Mean steady-state plasma concentrations during topotecan infusion ranged from 0.73 to 1.69 ng/ml, and mean etoposide concentrations ranged from 60 to 230 ng/ml. This sequence of topotecan, carboplatin, and etoposide appeared tolerable and active. Neutropenia was the dose-limiting toxicity.

Effective dosing of topotecan with carboplatin in relapsed ovarian cancer: a phase I/II study

PURPOSE

This phase I/II study was performed to evaluate the feasibility of administering the topoisomerase inhibitor topotecan in combination with carboplatin.

PATIENTS AND METHODS

Topotecan was given as a 30-minute infusion daily for 5 days, with carboplatin given immediately after topotecan on day 5. Treatment was repeated every 21 days. Carboplatin and then topotecan were escalated in sequential cohorts of three to six patients. Four dosage combinations of topotecan days 1 to 5 and carboplatin (day 5) were tested: 0.5 mg/m(2)/d and carboplatin area under the curve (AUC) of 4, topotecan 0.5 mg/m(2)/d and carboplatin AUC of 5, topotecan 0.75 mg/m(2)/d and carboplatin AUC of 5, and topotecan 1.0 mg/m(2)/d and carboplatin AUC of 5.

RESULTS

Grade 3 and 4 neutropenia was common at doses of 0.75 mg/m(2)/d and above, but dose-limiting hematologic toxicity occurred in only one patient. The most common reason for dose reduction or delay was failure of myelosuppression to resolve by day 21. Nonhematologic toxicity was generally mild. The maximum-tolerated dose as defined in the protocol was not reached, but topotecan dose escalation was stopped at 1.0 mg/m(2)/d, because delayed neutrophil recovery precluded re-treatment on a 21-day schedule.

CONCLUSION

Hematologic toxicity was common but rarely serious, and the combination of topotecan with carboplatin on this schedule was safe and well tolerated. Giving carboplatin to patients after topotecan on day 5, rather than on day 1, allowed dose escalation beyond the levels reported in other studies. The recommended doses for previously treated patients are topotecan 0.75 mg/m(2)/d, days 1 to 5, with carboplatin at an area under the curve (AUC) of 5 following topotecan on day 5. The combination of topotecan 1 mg/m(2)/d, days 1 to 5, followed on day 5 by carboplatin at an AUC of 5, merits further examination in untreated patients.

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.

Phase II feasibility study of sequential couplets of Cisplatin/Topotecan followed by paclitaxel/cisplatin as primary treatment for advanced epithelial ovarian cancer: a National Cancer Institute of Canada Clinical Trials Group Study

PURPOSE

Despite the improved results in advanced ovarian cancer achieved with the addition of paclitaxel to frontline therapy, there remains room for improvement. One approach is to add new agents such as topotecan. Because myelosuppression limits the delivery of topotecan with paclitaxel/cisplatin in a three-drug combination, we explored giving sequential couplets of cisplatin/topotecan followed by paclitaxel/cisplatin.

PATIENTS AND METHODS

Forty-four patients with residual epithelial ovarian carcinoma after primary surgery were studied. Cisplatin 50 mg/m(2) on day 1 and topotecan 0.75 mg/m(2) on days 1 through 5 were administered at 21-day intervals for four cycles, followed by interval debulking surgery (if optimal debulking was not achieved with primary surgery), and then paclitaxel 135 mg/m(2) over 24 hours on day 1 and cisplatin 75 mg/m(2) on day 2 at 21-day intervals for four cycles.

RESULTS

Such sequential couplets are feasible. Myelotoxicity was the major toxic effect, but it was of short duration. The granulocyte nadir with topotecan/cisplatin occurred late (median, day 18), so retreatment on day 21 was not always possible. There was no unexpected nonhematologic toxicity. The regimen was active in this group of patients who had undergone largely suboptimal debulking surgery. In 34 patients with clinically measurable disease, the overall response rate was 78%, and 30 (77%) of the 39 patients with elevated CA 125 levels at baseline had normalization of CA 125 levels by the end of therapy.

CONCLUSION

Sequential couplets of cisplatin/topotecan followed by paclitaxel/cisplatin are feasible. The efficacy data in this suboptimal group of patients has encouraged us to proceed with a randomized study based on this approach.

Gender-dependent pharmacokinetics of topotecan in adult patients

Gender-dependent differences in the clinical pharmacokinetic behavior of various drugs have been documented previously. Most commonly, these differences are associated with differences in body composition, renal elimination, drug absorption or hepatic metabolism. Gender-dependent differences in the pharmacokinetics of topotecan (Hycamtin) have not yet been described. In this report, pharmacokinetic data of the lactone and carboxylate forms of topotecan were derived from clinical studies in which topotecan was administered either orally or i.v. to a total of 55 males and 37 females. A significant difference (p=0.0082) of 38% was found between the apparent clearance of topotecan lactone after oral administration in males (237+/-105 l/h) and females (163+/-62.5 l/h). When adjusted for body surface area, this difference remained significant (p=0.031). Similarly, differences were noted in the percentage of topotecan in the lactone form (37.1+/-5.32 versus 41.7+/-6.51%, p=0.0076). Statistical analysis revealed that individual hematocrit values, which were consistently lower in females (p<0.023), were a significant predictor of the apparent topotecan lactone clearance. This was confirmed experimentally in in vitro incubation studies in whole blood using artificially altered hematocrit values and in blood samples from both male and female volunteers. Topotecan is thus subject to significant gender-dependent differences in pharmacokinetics that arise as a result of a physiological difference in hematocrit values between males and females. This finding may have significant implications for the interpretation of the relationships between pharmacokinetics and pharmacodynamic outcome of topotecan treatment, and may provide a basis for the development and refinement of future clinical protocols.