Inhibition of cis-diamminedichloroplatinum (II)-induced DNA interstrand cross-link removal by 7-ethyl-10-hydroxy-camptothecin in HST-1 human squamous-carcinoma cells

Biweekly irinotecan plus cisplatin versus irinotecan alone as second-line treatment for advanced gastric cancer: a randomised phase III trial (TCOG GI-0801/BIRIP trial)

PURPOSE

We compared biweekly irinotecan plus cisplatin (BIRIP) with irinotecan alone as the second-line chemotherapy (SLC) for advanced gastric cancer (AGC).

METHODS

Patients with metastatic or recurrent gastric cancer refractory to S-1-based first-line chemotherapy were randomly assigned to receive BIRIP (irinotecan 60mg/m(2) plus cisplatin 30mg/m(2), every 2weeks) or irinotecan alone (irinotecan 150mg/m(2), every 2weeks). The primary end-point was to show the superiority of BIRIP to irinotecan in terms of progression free survival (PFS).

RESULTS

130 patients were enrolled. PFS was significantly longer in the BIRIP group (3.8months [95% confidence interval (CI) 3.0-4.7]) than in the irinotecan group (2.8months [2.1-3.3]; hazard ratio 0.68, 95% CI 0.47-0.98; P=0.0398). Median overall survival was 10.7months in the BIRIP group and 10.1months in the irinotecan group (HR 1.00, 95% CI 0.69-1.44, P=0.9823). The objective response rate was 22% in the BIRIP group and 16% in the irinotecan group (P=0.4975). However, the disease control rate was significantly better in the BIRIP group (75%) than in the irinotecan group (54%, P=0.0162). The incidences of grade 3 or worse adverse events did not differ between the two groups. Any grade elevation of serum creatinine was more common in the BIRIP group (25% versus 8%, P=0.009), but any grade diarrhoea (17% versus 42%, P=0.002) was more common in the irinotecan group.

CONCLUSION

BIRIP significantly prolonged PFS as compared with irinotecan alone and was tolerated as SLC, but did not demonstrate the survival benefit in this trial.

Fatty acid synthase inhibitor cerulenin inhibits topoisomerase I catalytic activity and augments SN-38-induced apoptosis

Fatty acid synthase (FASN) is overexpressed in a wide variety of human cancers, making it an attractive target for anticancer therapy. One of the most widely used inhibitors of FASN, cerulenin, is a natural product of Cephalosporium caerulens. Cerulenin is selectively toxic to human cancer cells in vitro. However, the mechanism by which FASN inhibition causes apoptosis in tumor cells remains unclear. Because of the widespread clinical interest in combining cerulenin with other chemotherapeutic agents, we performed this study to gain insight into the downstream effects of FASN inhibition that lead to apoptosis. Here, we observed the increased antitumor effect of cerulenin when combined with the topoisomerase inhibitor SN-38. We identified topoisomerase I as a potential mediator of cerulenin-induced apoptosis, possibly by upregulating intracellular polyunsaturation. Finally, we show that suppressing topoisomerase I catalytic activity results in synergistic effects between cerulenin and LY294002. Our results suggest that topoisomerase I could participate in cerulenin-induced apoptosis by upregulating intracellular polyunsaturation. These results will help determine the molecular basis of the cerulenin and SN-38 drug combination. Further investigation of this pathway will provide new insight into cancer cell metabolism and may aid in the design of additional cancer chemotherapeutic agents.

Therapeutic intervention by the simultaneous inhibition of DNA repair and type I or type II DNA topoisomerases: one strategy, many outcomes

Many anticancer drugs reduce the integrity of DNA, forming strand breaks. This can cause mutations and cancer or cell death if the lesions are not repaired. Interestingly, DNA repair-deficient cancer cells (e.g., those with BRCA1/2 mutations) have been shown to exhibit increased sensitivity to chemotherapy. Based on this observation, a new therapeutic approach termed 'synthetic lethality' has been developed, in which radiation therapy or cytotoxic anticancer agents are employed in conjunction with selective inhibitors of poly(ADP-ribose)polymerase-1 (PARP-1). Such combinations can cause severe genomic instability in transformed cells resulting in cell death. The synergistic effects of combining PARP-1 inhibition with anticancer drugs have been demonstrated. However, the outcome of this therapeutic strategy varies significantly between cancer types, suggesting that synthetic lethality may be influenced by additional cellular factors. This review focuses on the outcomes of the combined action of PARP-1 inhibitors and agents that affect the activity of DNA topoisomerases.

A phase II study of a combined biweekly irinotecan and monthly cisplatin treatment for metastatic or recurrent gastric cancer

BACKGROUND

There is no universally confirmed standard chemotherapeutic regimen for advanced gastric cancer (AGC). The aim of this study was to investigate the efficacy and safety of combined biweekly irinotecan and monthly cisplatin treatments of patients with AGC. The primary end point was progression-free survival.

MATERIAL AND METHODS

AGC patients with or without measurable lesions received 70 mg/m2 irinotecan on days 1 and 15, and 80 mg/m2 cisplatin on day 1 every 4 weeks.

RESULTS

Of 40 enrolled patients, 21 patients had measurable disease. With a median follow-up duration of 35 weeks, the median progression-free survival and overall survival were 2.2 months and 8.0 months, respectively. The progression-free survival rate at 6 months was 30.0%. The most common adverse event of grade 3 to 4 was neutropenia (32.5%). Grade 3 diarrhea was observed in 2 patients (5.0%). There was no treatment-related death.

CONCLUSION

Current combined biweekly irinotecan and monthly cisplatin treatment did not show activity comparable with other active regimens in AGC.

Drug ratio-dependent antitumor activity of irinotecan and cisplatin combinations in vitro and in vivo

Irinotecan and cisplatin are two established anticancer drugs, which together constitute an effective combination for treating small-cell lung cancer. We investigated whether the efficacy of this combination could be improved by controlling drug ratios following in vivo administration. Irinotecan and cisplatin combinations were evaluated systematically for drug ratio-dependent synergy in vitro using a panel of 20 tumor cell lines. In vitro screening informatics on drug ratio-dependent cytotoxicity identified a consistently antagonistic region between irinotecan/cisplatin molar ratios of 1:2 to 4:1, which was bordered by two synergistic regions. Liposomal co-formulations of these two agents were developed that exhibited plasma drug half-lives of approximately 6 hours and maintained a fixed drug ratio for more than 24 hours. Drug ratio-dependent antitumor activity was shown in vivo for these liposome formulations, and irinotecan/cisplatin ratios between 5:1 and 10:1 were identified as therapeutically optimal. The relationship between irinotecan/cisplatin ratio and in vivo efficacy was consistent with in vitro drug ratio dependency results. Superior antitumor activity was observed for the liposome-encapsulated 7:1 molar ratio of irinotecan/cisplatin (designated CPX-571) compared with the free-drug cocktail in all models tested. Further efficacy studies in a range of human tumor xenografts, including an irinotecan-resistant model, showed that both liposomal agents contributed to the overall efficacy in a manner consistent with in vivo synergy. These results show the ability of drug delivery technology to enhance the therapeutic activity of irinotecan/cisplatin combination treatment by maintaining synergistic ratios in vivo. CPX-571, a fixed-ratio formulation of irinotecan and cisplatin, is a promising candidate for clinical development.

Mechanistic studies of the modulation of cleavage activity of topoisomerase I by DNA adducts of mono- and bi-functional PtII complexes

Using electrophoresis and replication mapping, we show that the presence of DNA adducts of bifunctional antitumor cisplatin or monodentate [PtCl(dien)]Cl (dien = diethylenetriamine) in the substrate DNA inhibits eukaryotic topoisomerase 1 (top1) action, the adducts of cisplatin being more effective. The presence of camptothecin in the samples of platinated DNA markedly enhances effects of Pt–DNA adducts on top1 activity. Interestingly, the effects of Pt–DNA adducts on the catalytic activity of top1 in the presence of camptothecin differ depending on the sequence context. A multiple metallation of the short nucleotide sequences on the scissile strand, immediately downstream of the cleavage site impedes the cleavage by top1. On the other hand, DNA cleavage by top1 at some cleavage sites which were not platinated in their close proximity is notably enhanced as a consequence of global platination of DNA. We suggest that this enhancement of DNA cleavage by top1 may consist in its inability to bind to other cleavage sites platinated in their close neighborhood; thus, more molecules of top1 may become available for cleavage at the sites where top1 normally cleaves and where platination does not interfere.

Paclitaxel, topotecan, and carboplatin in metastatic endometrial cancinoma: a Hellenic Co-operative Oncology Group (HeCOG) study

OBJECTIVE

Taxanes, and platinum compounds represent the chemotherapeutic agents with the greatest activity in metastatic endometrial carcinoma. We administered the combination of paclitaxel, topotecan and carboplatin to patients with metastatic or recurrent carcinoma of the endometrium to evaluate its activity and to define its toxicity.

METHODS

Thirty-nine consecutive patients were treated on an outpatient basis with paclitaxel 150 mg/m(2), administered intravenously over a 3-h period and followed by carboplatin at AUC of 5 on day 3, with both agents proceding topotecan that was given at 0.75 mg/m(2)/day on days 1 through 3. The chemotherapy was repeated every 3 weeks with granulocyte colony-stimulating factor (G-CSF) support for a maximum of six courses.

RESULTS

Twenty-one (60%) patients achieved objective clinical response (95% CI, 42.2-75.7%) including 4 (11.4%) complete and 17 (48.6%) partial responses. The median times to progression and survival for all patients were 8.9 and 17.7 months, respectively. Grade 3 or 4 thombocytopenia and neutropenia occurred in 5 (13%) and 4 (10%) patients, respectively, but only 2 episodes of neutropenic fever were encountered. Grade 2 or 3 neurotoxicity was observed in 23% of patients.

CONCLUSIONS

The combination of paclitaxel, topotecan and carboplatin with G-CSF support appears active with acceptable toxicity in patients with metastatic or recurrent carcinoma of the endometrium.

Irinotecan-cisplatin interactions assessed in cell-based screening assays: cytotoxicity, drug accumulation and DNA adduct formation in an NSCLC cell line

PURPOSE

The use of in vitro drug cytotoxicity assays for the assessment of drug-drug interactions that lead to synergy may not take into account the many cellular determinants responsible for combination effects. Administration of the anticancer drug CPT-11, for example, is associated with rapid conversion of drug from its active lactone form to the inactive carboxylate form. Thus it is difficult to model, in vitro, the behavior of this drug when used as a single agent and when used in a combination setting, this factor may contribute to the interactions measured. Therefore, the objective of this study was to examine the influence of CPT-11 lactone ratio on the cellular accumulation of CPT-11 when used as a single agent and under conditions where it is used in combination with cisplatin.

METHODS

A fixed ratio experimental design was used and drug ratios of CPT-11 and cisplatin were judged to be antagonistic, additive, or synergistic to the non-small cell lung cancer cell line, H460, on the basis of the median effect analysis methodology of Chou and Talalay. The influence of extracellular pH on CPT-11 accumulation was evaluated at pH 7.4 and pH 6.6 when the drug was added immediately to the cells or first pre-equilibrated at the indicated pH. These studies were completed in the presence and absence of cisplatin.

RESULTS

When CPT-11 was added as a single agent to cells in pH = 7.4 media, the drug underwent hydrolysis to the carboxylate form; however, there was a rapid accumulation of the CPT-11 lactone form which peaked at 3,800 pmol/mg protein by 30 min and drops to 570 pmol/mg protein by 24 h. In pH = 6.6 media, accumulation of CPT-11 lactone was substantially lower over a 60 min timecourse; however, the cellular uptake measured at 24 h was comparable to that observed when the drug was added into pH 7.4 media. When evaluating CPT-11 lactone accumulation in a combination setting with cisplatin no significant difference in either CPT-11 lactone accumulation or cisplatin accumulation was observed, suggesting that drug interactions that led to synergy were mechanistically based. Results are presented which suggest that when cisplatin and CPT-11 are used in combination, there was a significant prolongation of platinum association with DNA compared to results obtained when cisplatin was used alone.

CONCLUSION

These results suggest that the CPT-11 lactone to carboxylate ratio does not influence the accumulation of the active CPT-11 lactone form in H460 cells and that CPT-11 does not influence cisplatin uptake when used in combination. It is argued, therefore, that the improved cytotoxicity between CPT-11 and cisplatin, as determined using cell-based assay, has the potential to be preserved in vivo assuming the optimal drug-drug ratio and concentration can be effectively delivered to the tumor.

A phase II trial of weekly fractionated irinotecan and cisplatin for advanced gastric cancer

PURPOSE

This study was to evaluate the activity and the safety of a combination chemotherapy regimen of weekly fractionated irinotecan and cisplatin in advanced gastric cancer patients.

METHODS

Patients with advanced gastric adenocarcinoma with either chemotherapy-naive or only one prior chemotherapy regimen received irinotecan 50 mg/m2 followed by cisplatin 30 mg/m2. Both drugs were administered weekly for 3 consecutive weeks, followed by 1-week rest. Treatment was repeated until disease progression occurred. Response evaluation was performed according to the RECIST criteria.

RESULTS

Forty-seven patients (13 chemo-naive, 34 prior chemotherapy) were enrolled. Of 46 evaluable patients, overall response rate was 25.5% (95% CI, 12.9-39.3%) and disease control rate was 63.8% (95% CI, 50.9-79.5%) by intent-to-treat analysis. The time to progression and overall survival duration were 21 and 44 weeks, respectively. One-year survival rate was 41.6%. The most frequent grade 4 toxicity was neutropenia, which was the major cause of treatment delay. Non-hematological toxicities of grade 3-4 were rare with occurrence rate of 14.9% for anorexia and emesis.

CONCLUSIONS

Fractionated irinotecan combined with cisplatin with 3-week-on and 1-week-off schedule produced favorable clinical results for advanced gastric cancer. Because of the feasible efficacy and low non-hematologic toxicity, this treatment could be a promising salvage regimen in patients who have failed to taxanes.

Randomized Phase II study of two opposite administration sequences of irinotecan and cisplatin in patients with advanced nonsmall cell lung carcinoma

BACKGROUND

Combined chemotherapy with irinotecan and cisplatin (IP) is active in patients with nonsmall cell lung carcinoma (NSCLC). However, the optimal administration schedule needs to be defined to maximize its synergic effect. The authors evaluated the efficacy, toxicity, and pharmacokinetics (PK) of IP chemotherapy given on two administration sequences in chemotherapy-naive patients with NSCLC.

METHODS

Eighty eligible patients were assigned randomly to receive 1 of 2 irinotecan and cisplatin administration sequences on Day 1: irinotecan followed by cisplatin (I-P) (n = 39 patients) or cisplatin followed by irinotecan (P-I) (n = 41 patients). Treatment was comprised of irinotecan at a dose of 80 mg/m(2) intravenously on Days 1 and 8 and cisplatin at a dose of 60 mg/m(2) intravenously on Day 1 of a 21-day cycle for a maximum of 6 cycles. For PK analysis, serial plasma samples were obtained on Day 1 of the first cycle.

RESULTS

In total, 77 patients were assessable for efficacy. The overall response rate was 47%, and there was a trend in favor of P-I (54%) compared with I-P (39%). In multivariate logistic regression analysis, the P-I sequence and female gender were found to be significant predictors of a better response (P = 0.047 and P = 0.011, respectively). Overall toxicity profiles and PK parameters were similar in both arms.

CONCLUSIONS

IP chemotherapy showed promising activity with a favorable 1-year survival rate. For future clinical use, the authors recommend administering cisplatin first and then irinotecan, because that sequence was associated with a higher response rate.

Irinotecan plus cisplatin combination against metastatic gastric cancer: phase II study

In this phase II study, we aimed to detect efficacy and toxicity of the combination of CPT-11 and cisplatin administered to patients with metastatic gastric carcinoma. On d 1, CPT-11, 100 mg/m2, was administered by intravenous infusion for 90 min, followed by a 2 h infusion of cisplatin, at 70 mg/m2 every 3 wk. Forty-one patients were enrolled into the study. Twenty-eight patients were chemotherapy naive. The total number of chemotherapy cycles administered was 165, and the median number of cycles received was 4 (range, 1-8 cycles). The median follow-up time was 12 mo (range, 4-34 mo). There were 4 complete responses (9.7%) and 14 partial responses (34.2%), which result in a response rate of 43.9% (18 of 41 patients). The median time to progression was 8.0 +/- 0.8 mo with 56% and 13% of patients progression free at 6 and 12 mo, respectively. The median overall survival was 9.0 +/- 1.1 mo, with 68 % and 32% of patients alive at 6 and 12 mo, respectively. Grade 3-4 nausea and vomiting was observed in five patients (12%) and grade 3-4 neutropenia in five patients (12%). Grade 3 infection was observed in only one patient (2%). Grade 2 transient liver dysfunction related to chemotherapy was observed in one patient (2%). Chemotherapy was stopped due to nephrotoxicity in one patient (2%). There was no treatment-related death. In conclusion, administration of CPT-11 and cisplatin in this particular dose every 3 wk is effective and well-tolerated treatment regimen.

A novel combination of cisplatin, irinotecan, and capecitabine in patients with advanced cancer

BACKGROUND

We conducted a dose escalation study combining cisplatin, irinotecan, and capecitabine (CIC), aiming to establish the maximum tolerated doses (MTD), side effect profile, and dose-limiting toxicity (DLT) of this novel regimen.

PATIENTS AND METHODS

Intravenous cisplatin and irinotecan were to be administered on days 1 and 8, and oral capecitabine on days 1-14 of a 3-week cycle. The study was conducted in three parts. Part A: escalating doses of irinotecan (40 --> 80 mg/m2) and capecitabine (1000 --> 3300 mg/d) combined with a fixed dose of cisplatin (30 mg/m2). Part B: escalating doses of irinotecan (MTD-A --> MTD-A + 40 mg/m2) with fixed doses of cisplatin (20 mg/m2) and capecitabine (MTD-A level). Part C: escalating doses of capecitabine (1300 mg/d-->2600 mg/d) with fixed doses of cisplatin (20 mg/m2) and irinotecan (60 mg/m2).

RESULTS

Of 51 eligible patients 27 (53%) were male, median age was 58 years and 88% had PS 0-1. Major primary disease sites were colorectal (24%), unknown (14%), stomach (14%), and pancreas (12%). MTD-A was cisplatin 30 mg/m2, irinotecan 60 mg/m2, capecitabine 1000 mg/d and MTD-B was cisplatin 20 mg/m2, irinotecan 90 mg/m2, capecitabine 1000 mg/d. An MTD was not formally established for part C. DLTs consisted of infection with neutropenia (1), diarrhea and fatigue (1), hypokalemia (1), diarrhea and febrile neutropenia (1) and C2 delay of > or = 2 weeks or 25% dose reduction in C1 due to neutropenia or thrombocytopenia (6). Seven patients had a partial response to treatment (four colorectal, one SCLC, one NSCLC, one unknown primary), twenty seven SD (53%), twelve PD (24%) and five NE (10%).

CONCLUSION

CIC was associated with moderate toxicity and only modest antitumor activity. We conclude that this regimen has insufficient activity to justify further study in the phase II setting.

Weekly administration of irinotecan (CPT-11) plus cisplatin for refractory or relapsed small cell lung cancer

PURPOSE

Weekly administrations of CPT-11 plus cisplatin together with an anti-diarrheal program, the Oral Alkalization and Control of Defecation [Int J Cancer 1999;83:491; Int J Cancer 2001;92:269; Cancer Res 2002;62:179], were evaluated in this phase II study for patients with refractory or relapsed small cell lung cancer.

METHODS

Patients were treated by weekly administrations of 60 mg/m(2) CPT-11 plus 30 mg/m(2) cisplatin on Days 1, 8 and 15 over 4 weeks. Coinciding with the infusions and for 4 days thereafter, the anti-diarrheal program was practiced using orally administered sodium bicarbonate, magnesium oxide and basic water.

RESULTS

Twenty-five patients who had prior treatments of etoposide and platinum containing regimens (16 refractory patients and nine relapsed patients) were entered. The mean dose-intensities of CPT-11 and cisplatin were 154.8 and 77.4 mg/m(2) per course, respectively. Therefore, 86% of the planned dose was delivered. There were 20 partial responses and an overall response rate of 80% (95% confidence interval, 62-96%) was obtained. The median time to progression and the median survival after starting this regimen were 3.6 and 7.9 months, respectively. The major toxicity was myelosuppression. Grades 3 and 4 neutropenia occurred in 24 and 12% of patients, respectively. One patient with febrile neutropenia was experienced, and Grade 3 diarrhea was observed in 8%. But there was no treatment death.

CONCLUSION

Weekly administrations of CPT-11 plus cisplatin together with Oral Alkalization and Control of Defecation provide a practical and well tolerated regimen that was active for refractory or relapsed small cell lung cancer.

Advanced NSCLC: new cytostatic agents

There are several new cytostatic agents under investigation for the treatment of advanced non-small cell lung cancer either as first or second-line. In this review we will present the current information about oxaliplatin, epothilones, irinotecan and alimta.

Chemotherapy for small cell lung cancer

There were approximately 42,000 new cases of small cell lung cancer (SCLC) in 2002. Despite its initial sensitivity to chemotherapy, only 10% of all SCLC patients will have significant long-term survival. Studies have yet to show significant survival advantages for maintenance chemotherapy, and it appears that four to six cycles of chemotherapy is as effective as longer durations. As yet, there is no defined role for dose escalation in the treatment of SCLC. No one chemotherapy combination has exhibited a definitive survival advantage in extensive disease, although it appears that single-agent oral etoposide may be inferior to combination intravenous chemotherapy. In limited disease, however, cisplatin plus etoposide alone or in alternation with cyclophosphamide/doxorubicin/vincristine is superior to other approaches. There are several new agents with significant activity in SCLC awaiting further study.

DNA modifications by antitumor platinum and ruthenium compounds: their recognition and repair

The development of metal-based antitumor drugs has been stimulated by the clinical success of cis-diamminedichloroplatinum(II) (cisplatin) and its analogs and by the clinical trials of other platinum and ruthenium complexes with activity against resistant tumors and reduced toxicity including orally available platinum drugs. Broadening the spectrum of antitumor drugs depends on understanding existing agents with a view toward developing new modes of attack. It is therefore of great interest to understand the details of molecular and biochemical mechanisms underlying the biological efficacy of platinum and other transition-metal compounds. There is a large body of experimental evidence that the success of platinum complexes in killing tumor cells results from their ability to form various types of covalent adducts on DNA; thus, the research of DNA interactions of metal-based antitumor drugs has predominated. The present review summarizes current knowledge on DNA modifications by platinum and ruthenium complexes, their recognition by specific proteins, and repair. It also provides strong support for the view that either platinum or ruthenium drugs, which bind to DNA in a fundamentally different manner from that of 'classical' cisplatin, have altered pharmacological properties. The present article also demonstrates that this concept has already led to the synthesis of several new unconventional platinum or ruthenium antitumor compounds that violate the original structure-activity relationships.

Emerging role of topotecan in front-line treatment of carcinoma of the ovary

The conventional front-line chemotherapy strategy for advanced epithelial ovarian carcinoma has become adjuvant administration of platinum (carboplatin and cisplatin), either alone or, most often, in combination with a taxane. However, a number of active agents have been identified in phase II/III trials of second-line and salvage ovarian cancer patients that may augment this front-line strategy. One agent, topotecan, has antitumor activity comparable with paclitaxel in patients with recurrent ovarian cancer and is an established treatment in second-line or salvage settings. Additionally, its mechanism of action is different from paclitaxel and is nonoverlapping. These properties, coupled with the in vitro synergy observed in tumor models among topotecan, paclitaxel, and platinum, have provided the rationale for investigators to examine topotecan in front-line ovarian cancer therapy. A number of strategies for incorporating topotecan into front-line therapy are under active investigation, including the replacement of paclitaxel with topotecan, a triplet regimen with cisplatin or carboplatin and paclitaxel, a consolidation regimen consisting of several courses of a platinum agent and paclitaxel followed by several courses of topotecan, and a sequential doublet regimen in which patients receive platinum in every course as part of a doublet with alternating or sequential topotecan and paclitaxel. Preliminary data from ongoing clinical trials of these new regimens show favorable response rates and generally manageable toxicity profiles. This review summarizes the preliminary clinical findings associated with the four strategies and outlines ongoing and future randomized studies of topotecan in front-line ovarian cancer.

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.

Irinotecan in Non–Small-Cell Lung Cancer: Status of Ongoing Trials

Irinotecan possesses significant single-agent activity in non-small-cell lung cancer (NSCLC) and is active in combination with either cisplatin or carboplatin. Two phase III trials completed in Japan have suggested that the combination of irinotecan/cisplatin yields superior survival rates in stage IV NSCLC patients compared to vindesine/cisplatin. The principal toxicities of the irinotecan/cisplatin regimen are neutropenia and diarrhea. This regimen is currently being tested in Japan against regimens commonly used in the United States, such as cisplatin/gemcitabine, cisplatin/vinorelbine, and carboplatin/paclitaxel. These studies include evaluation of monthly as well as weekly schedules of cisplatin in combination with irinotecan as well as a triplet regimen of irinotecan/carboplatin/paclitaxel. Ongoing trials are evaluating these regimens as well as irinotecan/carboplatin and several nonplatinum-based irinotecan-containing doublets in both the first- and second-line treatment of advanced NSCLC. Several ongoing trials are attempting to integrate irinotecan with thoracic radiation therapy in stage III NSCLC. These trials are using irinotecan-containing regimens as induction and concurrent therapy with thoracic radiation therapy. Irinotecan is also being evaluated in the preoperative setting in early-stage resectable NSCLC. Many of these trials are also incorporating celecoxib, a potent inhibitor of the cyclooxygenase-2 pathway, in combination with irinotecan-containing regimens in both advanced as well as early-stage NSCLC. Future trials should focus on the integration of the new targeted agents in combination with irinotecan-containing regimens in all stages of NSCLC.

Phase II trial of irinotecan, paclitaxel and carboplatin in patients with previously untreated Stage IIIB/IV nonsmall cell lung carcinoma

BACKGROUND

This Phase II multicenter, open-label, single-arm study evaluated the efficacy and safety of a three-drug combination of irinotecan (CPT-11), paclitaxel, and carboplatin in advanced nonsmall cell lung carcinoma (NSCLC).

METHODS

Patients received repeated 21-day cycles at starting doses of paclitaxel 175 mg/m(2) administered over 3 hours, followed by carboplatin AUC of 5 over 30 minutes and CPT-11 at a starting dose level of 100 mg/m(2) over 90 minutes, all given on the first day of each cycle. Patients were evaluated for objective tumor response, time to tumor progression (TTP), survival, and safety.

RESULTS

Forty patients were enrolled. Baseline patient characteristics included: median age 58 years (range, 32-79); 23 males and 17 females; performance status of 0 (21 patients), 1 (18 patients), or 2 (1 patient); and Stage IIIB (10 patients) and Stage IV (30 patients) disease. A median of six cycles (range, one to eight) were administered. Grade 3-4 toxicities observed in >/= 10% of the patients included neutropenia (78%), asthenia (20%), diarrhea (20%), nausea (18%), vomiting (13%), anemia (10%), and dyspnea (10%). Febrile neutropenia occurred in eight patients (20%), with one death due to neutropenic sepsis. Twelve of 38 evaluable patients had confirmed tumor responses (32%), while 21 (55%) had stable disease (including 12 patients [32%] with minor responses). Only 13% had disease progression at their initial tumor assessment. The median TTP and survival were 5.3 months (range, 0.03-6.2 months) and 12.5 months (range 0.3-28.6+ months), respectively. The one and two year survival probabilities were 0.50 (95% confidence interval [CI], 0.28-0.73) and 0.21 (95% CI, 0.0-0.67), respectively.

CONCLUSIONS

The combination of CPT-11, paclitaxel, and carboplatin can be safely administered and is active in the treatment of advanced NSCLC. Based on the favorable survival outcome, this regimen is undergoing evaluation in prospective randomized trials.

Combination of oxaliplatin and irinotecan on human colon cancer cell lines: activity in vitro and in vivo

The in vitro and in vivo combination of oxaliplatin and irinotecan was investigated in a panel of four human colon cancer cell lines and their counterpart xenografts. In vitro and in vivo experiments demonstrated a synergistic or additive interaction in three cell lines (HCT-116, HCT-8 and HT-29) and an antagonism in SW-620 cells. Since there were clearly opposite interactions depending on the cell line, we further investigated cellular determinants possibly involved in the interaction between the two drugs in HCT-8 and SW-620 cells. Irinotecan slowed down the early platinum-DNA adducts repair (1 h after oxaliplatin exposure) in the presence of irinotecan only in HCT-8 cells (p=0.03, n=3). Moreover, a decrease of the expression of two proteins of the nucleotide excision repair (NER) system, ERCC1 and XPA, was observed. None of these effects was seen in SW-620 cells. Irinotecan induced apoptosis with an increase of poly(ADP-ribose) polymerase (PARP) cleavage in SW-620 cells (60 versus 7% basal level). Pretreatment of these cells with oxaliplatin abolished the increase in PARP cleavage induced by irinotecan (29%). In HCT-8 cells, a very little PARP cleavage was observed whatever the drug treatment. The persistence of platinum-DNA adducts in the presence of irinotecan could be due to a direct impact of irinotecan on NER gene expression or to an indirect effect on topoisomerase I activity. Complementary studies are required to determine if the cellular parameters identified in this study could be translated at the clinical level to predict clinical response after combined treatment with oxaliplatin and irinotecan in humans.

Irinotecan (CPT-11) in Triplet Combinations in Patients with Advanced Non–Small-Cell Lung Cancer: A Review and Report of a Phase I/II Trial

The objectives of this phase I/II trial were to determine the maximum tolerated dose, toxicities, and the dose suitable for phase II/III trials of irinotecan (CPT-11) combined with paclitaxel and carboplatin in patients with advanced non small-cell lung cancer (NSCLC). Seventy-three patients with stage IIIB/IV NSCLC were enrolled in this multicenter, phase I/II study. The initial regimen was paclitaxel 225 mg/m2 over 3 hours, followed by carboplatin at an area under the curve (AUC) of 6 over 30 minutes on day 1 and CPT-11 starting at 40 mg/m2 over 90 minutes on days 1 and 8, every 3 weeks. Dose-limiting toxicity occurred in three of the original seven patients. The regimen was amended with doses reduced to paclitaxel 175 mg/m2 over 3 hours, carboplatin AUC = 5, and CPT-11 at 40 mg/m2, all on day 1 every 3 weeks. Dose escalation of CPT-11 proceeded to 80 mg/m2 and 125 mg/m2 before dose-limiting toxicities were experienced. Subsequent patients received an intermediate CPT-11 dose of 100 mg/m2. Doses suitable for phase II study were determined to be paclitaxel 175 mg/m2 over 3 hours, carboplatin AUC = 5, and CPT-11 100 mg/m2. The pri-mary first-cycle dose-limiting toxicities were neutropenia and diarrhea. The most common grade 3/4 toxicity observed during all cycles was neutropenia. On the phase I portion of the study, objective tumor response was observed in 39% (12 of 31, 95% confidence interval: 22%-58%). The median time to tumor progression was 6.8 months, median survival was 11.0 months, and 1-year survival probability was 0.46. These data were confirmed in the phase II portion with a 30% objective response rate, median time to progression of 5.6 months, median survival of 12.5 months, and a 1-year survival probability of 0.50. In conclusion, CPT-11 100 mg/m2, paclitaxel 175 mg/m2, and carboplatin AUC = 5 given every 3 weeks can be safely administered in patients with advanced NSCLC. Neutropenia and diarrhea are the dose-limiting toxicities. The combination shows appreciable activity, and survival data are favorable, warranting further study of this regimen. A review of other irinotecan-containing triplet combinations is presented.

Phase I trial of the combination of irinotecan, paclitaxel, and carboplatin in patients with advanced non-small-cell lung cancer

PURPOSE

To determine the maximum-tolerated dose, toxicities, and dose suitable for phase II/III trials of irinotecan (CPT-11) combined with paclitaxel and carboplatin in patients with advanced non-small-cell lung cancer (NSCLC).

PATIENTS AND METHODS

Patients with stage IIIB/IV NSCLC were enrolled to this multicenter, phase I study. The initial regimen was paclitaxel 225 mg/m(2)/3 h, followed by carboplatin area under the curve (AUC) 6 over 30 minutes on day 1, and CPT-11 starting at 40 mg/m(2) over 90 minutes, days 1 and 8, every 3 weeks. Dose-limiting toxicity occurred in three of seven patients. The regimen was amended, with doses reduced to paclitaxel 175 mg/m(2)/3 h, carboplatin AUC 5 and CPT-11 at 40 mg/m(2), all on day 1 every 3 weeks. Dose escalation of CPT-11 proceeded to 80 mg/m(2) then 125 mg/m(2) before dose-limiting toxicities were experienced. Subsequent patients received an intermediate CPT-11 dose of 100 mg/m(2).

RESULTS

Thirty-three patients were enrolled; 32 patients were assessable for safety, and 31 were assessable for tumor response. The primary first-cycle dose-limiting toxicities were neutropenia and diarrhea. The most common grade 3/4 toxicity observed during all cycles was neutropenia (16 patients [50%], with six [19%] developing neutropenic fever). Objective tumor response was observed in 39% (12/31, 95% confidence interval, 22% to 58%). The median time to tumor progression was 6.8 months, median survival 11.0 months, and 1-year survival probability 0.46.

CONCLUSION

CPT-11 100 mg/m(2), paclitaxel 175 mg/m(2), and carboplatin AUC 5 given every 3 weeks can be safely administered in patients with advanced NSCLC. Neutropenia and diarrhea are the dose-limiting toxicities. The combination shows appreciable activity, and survival data are favorable.

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

PURPOSE

In in vitro studies, synergism and sequence-dependent effects were reported for the combination of topotecan and cisplatin. Recently, an oral formulation of topotecan became available. This phase I study was performed to assess the feasibility of the combination of oral topotecan and cisplatin, the pharmacokinetic interaction, and sequence-dependent effects.

PATIENTS AND METHODS

Topotecan was administered orally (PO) daily for 5 days in escalating doses and cisplatin was given intravenously (IV) at a fixed dose of 75 mg/m(2) either before topotecan administration on day 1 (sequence CT) or after topotecan administration on day 5 (sequence TC) once every 3 weeks. Patients were treated in a randomized cross-over design.

RESULTS

Forty-nine patients were entered onto the study; one patient was not eligible. Sequence CT induced significantly more severe myelosuppression than did sequence TC, and the maximum-tolerated dosage of topotecan in sequence CT was 1.25 mg/m(2)/d x 5. In sequence TC, the maximum-tolerated dosage of topotecan was 2.0 mg/m(2)/d x 5. Dose-limiting toxicity consisted of myelosuppression and diarrhea. Pharmacokinetics of topotecan and cisplatin were linear over the dose range studied; no sequence-dependent effects were observed. In addition, topotecan did not influence the protein binding of cisplatin or the platinum-DNA adduct formation in peripheral leukocytes in either sequence.

CONCLUSION

The recommended dosages for phase II studies involving patients like the patients in our study are topotecan 1.25 mg/m(2)/d PO x 5 preceded by cisplatin 75 mg/m(2) IV day 1 once every 3 weeks, and topotecan 2.0 mg/m(2)/d PO followed by cisplatin 75 mg/m(2) IV day 5. No pharmacokinetic interaction could be discerned in our study. The antitumor efficacy of both schedules should be evaluated in a randomized phase II study.

Phase I study of 3-week schedule of irinotecan combined with cisplatin in patients with advanced solid tumors

PURPOSE

To assess the feasibility, pharmacokinetic interaction, and possible sequence-dependent effects of the irinotecan/cisplatin combination given every 3 weeks, and to assess the influence of additional granulocyte colony-stimulating factor (G-CSF) on the hematologic toxicity.

PATIENTS AND METHODS

Patients who had received no more than one prior combination chemotherapy regimen or two single-agent regimens were entered. Treatment consisted of a 90-minute irinotecan infusion followed by a 3-hour cisplatin infusion on day 1, with cycles repeated once every 3 weeks. After the maximum-tolerated dose was determined, the sequence of administration was reversed. In a separate cohort of six patients, we assessed the effect of G-CSF on the experienced hematologic toxicity and dose-intensity. Irinotecan doses ranged from 175 to 300 mg/m(2) and cisplatin doses ranged from 60 to 80 mg/m(2).

RESULTS

Fifty-two patients entered the study; one was not eligible, and two were not assessable for response. Twenty-five patients were pretreated, and 26 were not. Fifty-one patients received a total of 223 courses. The dose-limiting toxicity was a combination of neutropenic fever, diarrhea, and fatigue at a dose level combining irinotecan 300 mg/m(2) with cisplatin 80 mg/m(2). Neutropenia was common (grades 3 to 4, 68%). Irinotecan pharmacokinetics were linear over the dose range studied. No sequence-dependent side effects were observed. Tumor responses included three complete responses and eight partial responses.

CONCLUSION

For phase II studies, we recommend irinotecan 260 mg/m(2) combined with cisplatin 80 mg/m(2) once every 3 weeks for chemotherapy-naive patients in good physical condition, and irinotecan 200 mg/m(2) combined with cisplatin 80 mg/m(2) for other patients.

v-src induces cisplatin resistance by increasing the repair of cisplatin-DNA interstrand cross-links in human gallbladder adenocarcinoma cells

Activation of Src, which has an intrinsic protein tyrosine kinase (PTK) activity, has been demonstrated in human solid tumors, such as colorectal and breast cancers. To investigate the role of activated Src in drug resistance, we evaluated the effect of v-src on the resistance to various anti-cancer drugs using v-src-transfected HAG-1 human gallbladder adenocarcinoma cells. Compared with parental or mock-transfected HAG-1 cells, v-src-transfected HAG/src3-1 cells showed a 3.5-fold resistance to cis-diamminedichloroplatinum (II) (CDDP) but not to doxorubicin, etoposide or 5-fluorouracil. By contrast, activated H-ras, which acts downstream of src, failed to induce resistance to either of these drugs. Furthermore, wortmannin, a phosphatidylinositol (PI) 3-kinase inhibitor, and H7, a protein kinase C (PKC) inhibitor, did not alter CDDP resistance. Evaluation of the kinetics of the removal of DNA interstrand cross-links (ICLs), measured by alkaline elution, showed a significant increase in this removal in HAG/src3-1 cells as compared with mock-transfected cells, though no differences were found in the formation of DNA ICLs between these cell lines. CDDP resistance in v-src-transfected cells was reversed, if not completely, by either herbimycin A or radicicol, specific inhibitors of Src-family PTKs, suggesting that Src tyrosine kinase activity induces CDDP resistance. Moreover, significant reduction in the repair of CDDP-induced DNA ICLs was observed upon treatment with radicicol. The intracellular glutathione content and mRNA expression of topoisomerase II and metallothionein were virtually identical between these cell lines, except for topoisomerase I mRNA. Our data strongly suggest that the ability of activated src, but not ras, to induce CDDP resistance is mediated by augmentation of DNA repair through Src to downstream signal-transduction pathways distinct from either the Ras, PI 3-kinase or PKC pathway.

Topoisomerase-I inhibitors in gynecologic tumors

The first section of this article reviews recent studies that have clarified both the cellular role of topoisomerase I and the mechanisms of cytotoxicity of the topoisomerase inhibitors, the camptothecins. Different analogs of this new class of antitumor drug have been studied using various dose schedules in the treatment of refractory or recurrent gynecologic cancer. Response rates are between 13% and 25%. The main toxic effects are hematologic and gastrointestinal, the latter remains problematic. Radiotherapy, alkylate, platinum analogues, and topoisomerase II inhibitors are currently being studied in combination with camptothecins.

Cellular resistance to topoisomerase-targeted drugs: from drug uptake to cell death

DNA topoisomerase inhibitors are important antineoplastic agents used in the treatment of both leukemias and solid tumors, such as breast, lung and colon cancers. Their clinical usefulness is limited by both natural and acquired tumor cell resistance, which almost always is multifactorial in nature. The resistance can be due to pretarget events, such as drug accumulation, metabolism and intracellular drug distribution, or due to reduced drug-target interaction. More recently, post-target events, such as macromolecular synthesis, cell cycle progression, DNA repair/recombination and regulation of cell death, have been shown to play an important role in the sensitivity toward topoisomerase inhibitors. The different mechanisms involved in the cellular resistance toward clinically used topoisomerase inhibitors will be reviewed in this article with particular emphasis on post-target events.

Superhelical torsion controls DNA interstrand cross-linking by antitumor cis- diamminedichloroplatinum(II)

Negatively supercoiled, relaxed and linearized forms of pSP73 DNA were modified in cell-free medium by cis-diamminedichloroplatinum(II) (cisplatin). The frequency of interstrand cross-links (ICLs) formed in these DNAs has been determined by: (i) immunochemical analysis; (ii) an assay employing NaCN as a probe of DNA ICLs of cisplatin; (iii) gel electrophoresis under denaturing conditions. At low levels of the modification of DNA (<1 Pt atom fixed per 500 bp) the number of ICLs formed by cisplatin was radically enhanced in supercoiled in comparison with linearized or relaxed DNA. At these low levels of modification, the frequency of ICLs in supercoiled DNA was enhanced with increasing level of negative supercoiling or with decreasing level of modification. In addition, the replication mapping of DNA ICLs of cisplatin was consistent with these lesions being preferentially formed in negatively supercoiled DNA between guanine residues in both the 5'-d(GC)-3' and the 5'-d(CG)-3' sites. Among the DNA adducts of cisplatin the ICL has the markedly greatest capability to unwind the double helix. We suggest that the formation of ICLs of cisplatin is thermodynamically more favored in negatively supercoiled DNA owing mainly to the relaxation of supercoils.