A phase IB, open-label dose-escalating study of the oral angiogenesis inhibitor PTK787/ZK 222584 (PTK/ZK), in combination with FOLFOX4 chemotherapy in patients with advanced colorectal cancer.

BACKGROUND: This open-label, phase IB study was undertaken to determine the safety/toxicity profile and recommended dose of oral once-daily PTK787/ZK 222584 (PTK/ZK) combined with oxaliplatin/5-fluorouracil (5-FU)/leucovorin (FOLFOX4) chemotherapy in patients with advanced colorectal cancer. Secondary objectives were to assess full pharmacokinetics and gather preliminary evidence of antitumor activity. PATIENTS AND METHODS: Thirty-five patients received escalating doses of PTK/ZK (range 500-2000 mg daily) continuously. Concurrent FOLFOX4 chemotherapy was administered on days 1 and 2 and repeated every 14 days. Dose escalation of PTK/ZK was continued until maximum tolerated dose (MTD) was established and additional patients were then enrolled at MTD dosage. RESULTS: Mean treatment duration of PTK/ZK was 9.5 months. The MTD was 1250 mg daily with dizziness being the most frequent dose-limiting toxicity (DLT). Hypertension (23%, grade 3) and neutropenia (37%, grades 3 + 4) were the most frequent grade 3 or 4 adverse events. Pharmacokinetic analyses found no evidence for interactions between PTK/ZK and the combination of 5-FU, leucovorin, and oxaliplatin during concomitant use. Median progression-free survival was 11.4 months. CONCLUSION: The MTD of PTK/ZK in combination with FOLFOX4 in this patient population is 1250 mg daily. The combination is feasible and safe and is not associated with significant pharmacokinetic interactions.

Oral vinorelbine/paclitaxel combination treatment of metastatic breast cancer: a phase I study.

PURPOSE: Intravenous (i.v.) vinorelbine (VRL) generally given on days 1 and 8 of an every three-week cycle in combination with paclitaxel (PTX) is an effective option for the treatment of metastatic breast cancer (MBC). In an effort to improve both patient and chemotherapy unit convenience, oral VRL was used at equivalent doses of i.v. VRL. PATIENTS AND METHODS: The maximal tolerated dose (MTD) was determined during the first cycle of oral VRL given on days 1 and 8 or 15 and PTX infused over 3 h on day 1 every 3 weeks, maximum of 6 cycles. The dose of oral VRL was escalated from 60 to 80 mg/m2 in 10 mg/m2 increments. Paclitaxel was administered at 110 and then 135 mg/m2. The combination regimen was given as first-line chemotherapy of MBC. Three to six patients per cohort were treated. RESULTS: Twenty-two patients were treated in the first four cohorts (oral VRL/PTX): 60/110, 70/110, 80/110 and 80/135. In cohort 4, seven patients were treated, one patient being non-evaluable for MTD, three of them presented a dose-limiting toxicity (DLT) consisting of febrile neutropenia and neutropenic infection. Therefore 80/135 was the MTD. Because 36% of oral VRL administrations on day 8 were delayed to day 15 at 80/110, two additional cohorts were tested: in cohort 5, oral VRL 60 mg/m2 on days 1 and 15 and PTX 135 mg/m2 on day 1 and in cohort 6, oral VRL 80 mg/m2 on days 1 and 15 and PTX 110 mg/m2 on day 1, every 3 weeks. In cohort 5, six out of eight patients had DLTs: omission of oral VRL on day 15 for five patients, grade 4 neutropenia>7 days for another one. Therefore the recommended dose (RD) for further clinical testing was oral VRL 80 mg/m2 on days 1 and 15 and PTX 110 mg/m2 on day 1 of an every 3-week cycle. Two of the three evaluable patients treated at the RD had a partial response. The pharmacokinetics of VRL and PTX is being analysed and will be further presented in a separate publication. CONCLUSIONS: This phase I study has determined the doses of oral VRL and PTX to be used in combination for the benefit of the patient and of the chemotherapy unit in term of nurse's workload. The recommended regimen of oral VRL 80 mg/m2 on days 1 and 15 and PTX 110 mg/m2 on day 1 given every 3 weeks will be further tested in phase II.

Phase III study of weekly high-dose infusional fluorouracil plus folinic acid with or without irinotecan in patients with metastatic colorectal cancer: European Organisation for Research and Treatment of Cancer Gastrointestinal Group Study 40986.

PURPOSE: To demonstrate that adding irinotecan to a standard weekly schedule of high-dose, infusional fluorouracil (FU) and leucovorin (folinic acid [FA]) can prolong progression-free survival (PFS). PATIENTS AND METHODS: Four hundred thirty patients with measurable or assessable metastatic colorectal cancer were randomly assigned to receive either FA 500 mg/m(2) as a 2-hour infusion and FU 2.6 g/m(2) by intravenous 24-hour infusion, both administered weekly for 6 weeks, followed by a 2-week rest (Arbeitsgemeinschaft für Internistische Onkologie [AIO] arm, n = 216), or a similar schedule but with FU 2.3 or 2.0 g/m(2) preceded by irinotecan 80 mg/m(2) administered over 30 minutes (experimental group, n = 214). RESULTS: The median PFS time in the experimental group was 8.5 months (95% CI, 7.6 to 9.9 months) compared with 6.4 months (95% CI, 5.3 to 7.2 months) in the AIO arm (P < .0001). The median overall survival time was increased from 16.9 to 20.1 months (P = .2779). The objective response rate was 62.2% (95% CI, 55.0% to 69.5%) in the experimental group and 34.4% (95% CI, 27.5% to 41.3%) in the AIO arm (P < .0001). CONCLUSION: The addition of irinotecan to the standard AIO FU/FA regimen was associated with a highly significant improvement in PFS and response rate and was well tolerated. The results of this study confirm that irinotecan in combination with high-dose infusional FU/FA is a reference first-line treatment.

Adjuvant chemoradiation using 5-fluorouracil/folinic acid/cisplatin with or without paclitaxel and radiation in patients with completely resected high-risk gastric cancer: two cooperative phase II studies of the AIO/ARO/ACO.

BACKGROUND: The current two studies evaluate the feasibility, toxicity and efficacy of an adjuvant combined modality treatment strategy containing a three to four-drug chemotherapy regimen plus 5-fluorouracil (FU)-based radiochemotherapy. PATIENTS AND METHODS: Between December 2000 and October 2003, a total of 86 patients were included in both studies. Patients with completely resected gastric adenocarcinoma including a D1 or D2 lymph node dissection (LND) were eligible. Treatment consisted of two cycles of folinic acid 500 mg/m2, 5-FU 2000 mg/m2 continuous infusion over 24 h once weekly for 6 consecutive weeks, paclitaxel 175 mg/m2 in weeks 1 and 4 and cisplatin 50 mg/m2 in weeks 2 and 5 (FLPP; n=41) or two cycles of the same 5-FU/folinic acid schedule but with cisplatin 50 mg/m2 only in weeks 1, 3 and 5 (FLP; n=45). Radiation with 45 Gy plus concomitantly applied 5-FU 225 mg/m2/24 h was scheduled in between the two cycles. RESULTS: Patients characteristics were: D1/D2 LND FLP group 53%/42%; FLPP group 27%/68%; stage distribution: UICC stages III/IV(M0) FLP group 63% and FLPP group 66%. Median follow-up was 10 months (3-25) for FLP and 18 months (2-51) for FLPP patients. CTC grade 3/4 toxicities during the first cycle/chemoradiation/second cycle of FLP: granulocytopenia 3%/0/27%, anorexia 6%/10%/8%; diarrhea 8%/0/4%, nausea 3%/0/4%; FLPP: granulocytopenia 0/0/37%, anorexia 5%/11%/6%; diarrhea 5%/0/3, nausea 3%/8%/0%; early death in one patient due to Pneumocystis carinii pneumonia. Projected 2-year progression-free survival was 64% (95% CI 56% to 68%) for the FLP and 61% (95% CI 42% to 78%) for the FLPP group. CONCLUSIONS: Both chemoradiation regimens appear feasible with an acceptable toxicity profile indicating that cisplatin can be added to 5-FU/FA and that even a four-drug regimen can be investigated further in prospective clinical trials in completely resected gastric cancer patients. Treatment should be given in experienced centres in order to avoid unnecessary toxicity.

Phase I/II study of capecitabine and vinorelbine in pretreated patients with metastatic breast cancer.

PURPOSE: To define the maximum-tolerated dose (MTD) and to evaluate the dose-limiting toxicities (DLT) of the combination of capecitabine and vinorelbine in patients with metastatic breast cancer who relapse after adjuvant and/or first-line treatment. In addition, we aimed to obtain data on efficacy and safety at the recommended dose. PATIENTS AND METHODS: Patients with measurable metastatic breast cancer after failure of prior chemotherapy (including anthracyclines and/or taxanes) were eligible. Capecitabine was administered with a fixed dose of 1000 mg/m(2) orally twice daily for 2 weeks followed by 1 week rest. One treatment cycle consisted of 6 weeks of treatment containing two treatment periods of capecitabine. Vinorelbine was given intravenously at escalated doses of 25 mg/m(2) (dose level 1) and 30 mg/m(2) (dose level 2) on days 1 and 8, and 22 and 29. RESULTS: Thirty-three patients received a total of 91 cycles of capecitabine and vinorelbine. The median number of administered cycles per patient was three (range one to six). Thirty-one patients were evaluable for toxicity. At dose level 2 four out of seven patients experienced DLTs (nausea/vomiting, febrile neutropenia, grade 4 neutropenia, infection and diarrhea); thus, the MTD was defined. In order to confirm the safety and efficacy, dose level 1 was extended to 24 patients. Two patients [8.3%; 95% confidence interval (CI) 1% to 27%] showed DLTs (hospitalization due to febrile neutropenia and prolonged neutropenia). The main toxicity was neutropenia, which was observed at National Cancer Institute Common Toxicity Criteria grade 3 and 4 in 39% of patients. The overall response rate for capecitabine and vinorelbine was 55% (95% CI 36% to 72.7%), including three patients with a complete remission. The median time to disease progression was 8 months (95% CI 4.3-11.7) with an overall survival of 19.2 months (95% CI 11.3-27.1) based on intention-to-treat analysis. CONCLUSIONS: The combination of capecitabine and vinorelbine can be administered with manageable toxicity and showed significant efficacy for patients with metastatic breast cancer even after failure of a anthracycline- and/or taxane-based therapy.

High-dose chemotherapy with autologous stem cell transplantation in patients with oligometastatic breast cancer.

The purpose of this prospective trial was to study a combined-modality treatment including local consolidation by surgery or radiotherapy and high-dose chemotherapy (HDC) followed by peripheral-blood stem-cell (PBSC) transplantation. In all, 48 patients with oligometastatic breast cancer amenable to local treatment after induction chemotherapy with epirubicin and cyclophosphamide or paclitaxel and cisplatin, depending on prior adjuvant chemotherapy, were enrolled. The median follow-up was 41 months (range, 7-85 months). PBSC were collected in 47 patients, and 40 received one or two courses of HDC. Local therapy was given in 37 patients. No treatment-related deaths occurred. Of 47 evaluable patients, 36 (75% of intention-to-treat population) had no evidence of disease or complete remission after completion of therapy. Six patients (12.5%) had partial response, two patients (4%) no change, and three patients (6%) progressive disease. The median time to progression and overall survival was 17.5 (95% confidence interval (CI), 14-21 months) and 42.2 months (95% CI, 33-52 months), respectively, and 27% of patients were progression free after 5 years. In conclusion, patients with oligometastatic breast cancer can be treated safely with this combined modality protocol with promising relapse-free survivals.

Capecitabine and irinotecan as first-line chemotherapy in patients with metastatic colorectal cancer: results of an extended phase I study.

BACKGROUND: To define the maximum-tolerated dose (MTD) and to evaluate the dose-limiting toxicities (DLTs) of the combination of capecitabine and irinotecan in patients with metastatic colorectal cancer. PATIENTS AND METHODS: Thirty-seven patients with measurable metastatic colorectal cancer with no prior chemotherapy for metastatic disease were treated at three dose levels (DLs). For the first two dose levels, irinotecan (70 mg/m(2)) was administered once a week for 6 weeks in combination with 2 weeks of capecitabine at 1000 mg/m(2) (DL1) or 1250 mg/m(2) (DL2) twice daily, starting on days 1 and 22. In the last dose escalation step, the dose of irinotecan was increased to 80 mg/m(2) (DL3). One cycle lasted 7 weeks. RESULTS: In the subsequent phase I trial, 96 cycles of capecitabine and irinotecan were administered. At DL3, three out of six patients experienced DLTs (diarrhea, neutropenia, asthenia). In order to confirm the safety of the recommended dose, DL2 was extended to 15 patients. Five patients (33%) showed DLTs at this dose level, which was considered too high to embark on further clinical studies. Subsequently, the starting dose (DL1) was extended to a total of 16 patients, with diarrhea being the main toxicity. The overall response rate was 38% [95% confidence interval (CI) 21% to 58%], with a median response duration of 8.7 months (95% CI 6.4-11.5 months). CONCLUSIONS: The recommended doses for further studies are irinotecan 70 mg/m(2) and capecitabine 1000 mg/m(2). The combination of capecitabine and irinotecan appears to have significant therapeutic efficacy with manageable toxicity.

Irinotecan in metastatic colorectal cancer: dose intensification and combination with new agents, including biological response modifiers.

Phase I/II studies suggest that the combination of irinotecan with capecitabine is feasible and has promising activity. Diarrhea and neutropenia are dose limiting. Overall response rates (RRs) in the 40% to 60% range are seen from preliminary data. Work in progress is assessing the combination of irinotecan with UFT/leucovorin (LV). The use of irinotecan together with raltitrexed is also being investigated, as is its combination with oxaliplatin. Two phase II studies of irinotecan plus oxaliplatin in second-line patients report median survivals of 11-12 months. It seems possible to safely escalate the dose of single-agent irinotecan to 500 mg/m(2) in patients showing good tolerance of the drug. Irinotecan can be used in combination with LV5FU2 at doses up to 260 mg/m(2), especially if only one bolus of 5-fluorouracil (5-FU) is given. Control of tumor growth is achieved in 90% of patients. Preliminary data suggest that regimens based on 5-FU/LV and irinotecan can safely be combined with the anti-epidermal growth factor receptor (EGFR) antibody cetuximab. In patients with EGFR-positive tumors, this may prove an effective means of increasing response rate or combating treatment resistance. Following evidence that COX-2 inhibition can slow progression in familial adenomatous polyposis, celecoxib is to be studied in metastatic colorectal cancer (CRC). In vitro, the cyclin-dependent kinase inhibitor flavopiridol enhances the induction of apoptosis by chemotherapy. Clinically, it can safely be administered with irinotecan, and studies in CRC are planned.

[Patient with stomach cancer with metastases. What is the value of chemotherapy?]. / Magenkrebspatient mit Metastasen. Was leistet die Chemotherapie?

In comparison with supportive measures alone, chemotherapy in advanced gastric carcinoma is associated with a significant increase in survival and improvement in quality of life. The following substances are considered to be effective and suitable for combination therapy: 5-FU +/- folic acid, cisplatin, irinotecan, etoposide, taxol, and taxotere. In contrast, the effect of doxorubicin and epidoxorubicin is only moderate. Although "second generation" combinations, such as FAMTX, ELF or cisplatin/5-FU, induced higher remission rates as the "first generation" combinations, they failed to improve survival times to any appreciable extent. Currently accepted standard treatment of metastatic gastric carcinoma is infusional 5-FU + cisplatin or ECF. The third generation combinations containing taxane, irinotecan, oxaliplatin appear to be at least equally effective.

[Novel molecular approaches in the therapy of advanced colorectal carcinoma]. / Neue molekulare Ansätze in der Therapie des fortgeschrittenen kolorektalen Karzinoms.

Therapeutic options for patients with metastatic colorectal cancer have clearly improved during the last years. The regular use of irinotecan and oxaliplatin in first- and second-line treatment led to a clear improvement of median overall survival time. For the first time a new therapeutic concept--the inhibition of tumor angiogenesis--has been realized for clinical use by combining the anti-VEGF monoclonal antibody bevacizumab with an irinotecan-based first-line therapy. The monoclonal antibody cetuximab, targeted against EGFR, offers another new and very effective therapeutic option to patients with advanced irinotecan-refractory colorectal cancer--even those who are already pretreated with oxaliplatin. Further clinical studies are going to evaluate the future role of these new molecular treatment options as part of those therapeutic possibilities which are already available and established for the treatment of colorectal cancer patients with advanced disease (such as the optimal sequencing, the role of orale fluoropyrimidine-based combination therapy with cetuximab or bevacizumab).

Optimizing the use of irinotecan in colorectal cancer.

The introduction of new agents with novel mechanisms of action has led to considerable changes in the management of colorectal cancer in recent years. One of these novel agents, irinotecan, has been shown to offer survival benefits in both the first- and second-line treatment of advanced/metastatic colorectal cancer. Irinotecan monotherapy improves survival compared with both best supportive care and infused 5-fluorouracil (5-FU) in patients with 5-FU-pretreated disease, without impacting negatively on patients' quality of life. As a result, irinotecan monotherapy is now considered to be the standard treatment in this setting. Irinotecan in combination with 5-FU/leucovorin (LV) was subsequently evaluated as first-line therapy for metastatic colorectal cancer in two randomized, phase III studies. Both trials confirmed that irinotecan plus infused or bolus 5-FU/leucovorin LV provide a modest survival benefit without compromising patients' quality of life. Combined irinotecan/5-FU/LV represents a new standard in the first-line treatment of metastatic colorectal cancer. In an attempt to further improve efficacy and tolerability, recent studies have investigated irinotecan in combination with capecitabine as first-line treatment for colorectal cancer. The replacement of infused 5-FU with oral capecitabine provides a more convenient treatment option. A phase I study was conducted to establish the maximum tolerated dose, and demonstrated encouraging antitumor activity and a manageable safety profile with the combination. This article provides a brief overview of the pivotal clinical trial data for irinotecan and discusses how irinotecan-based therapy may be improved in the future. It also discusses potential optimization of irinotecan use through identification of patient subpopulations most likely to benefit from combination or sequential strategies, and the potential of new, oral agents such as capecitabine to replace i.v. 5-FU as a combination partner for irinotecan.

Irinotecan in the treatment of colorectal cancer: clinical overview.

PURPOSE AND METHODS: For more than three decades, the therapeutic options for patients with advanced colorectal cancer have almost exclusively been based on fluoropyrimidines. With the recognition that topoisomerase-I (TOP-I) is an important therapeutic target in cancer therapy, irinotecan, a semisynthetic TOP-I-interactive camptothecin derivative, has been clinically established in the treatment of colorectal cancer. RESULTS: Irinotecan was investigated as second-line chemotherapy after prior treatment with fluorouracil (FU)-based regimens in two large randomized phase III trials comparing irinotecan with either best supportive care or an infusional FU/leucovorin (LV) regimen. The outcomes of these trials established irinotecan as the standard therapy in the second-line treatment of colorectal cancer. The therapeutic value of irinotecan in the first-line treatment of metastatic colorectal cancer was investigated in two large randomized phase III trials comparing the combination of irinotecan and FU/LV with FU/LV alone. Both trials demonstrated significant superior efficacy for the combination of irinotecan and FU/LV in terms of response rate, median time to disease progression, and median survival time. Consequently, the combination of irinotecan and FU/LV has been approved as first-line chemotherapy for patients with metastatic colorectal cancer and constitutes the reference therapy against which other treatment options must be tested in the future. CONCLUSION: In this review, the clinical rationale and update of the present clinical status of irinotecan in the treatment of colorectal cancer and future prospects of irinotecan-based combinations are discussed.

D-24851, a novel synthetic microtubule inhibitor, exerts curative antitumoral activity in vivo, shows efficacy toward multidrug-resistant tumor cells, and lacks neurotoxicity.

N-(pyridin-4-yl)-[1-(4-chlorbenzyl)-indol-3-yl]-glyoxyl-amid (D-24851) is a novel synthetic compound that was identified in a cell-based screening assay to discover cytotoxic drugs. D-24851 destabilizes microtubules and blocks cell cycle transition specifically at G2-M phase. The binding site of D-24851 does not overlap with the tubulin binding sites of known microtubule-destabilizing agents like vincristine or colchicine. In vitro, D-24851 has potent cytotoxic activity toward a panel of established human tumor cell lines including SKOV3 ovarian cancer, U87 glioblastoma, and ASPC-1 pancreatic cancer cells. In vivo, oral D-24851 treatment induced complete tumor regressions (cures) in rats bearing Yoshida AH13 sarcomas. Of importance is that the administration of curative doses of D-24851 to the animals revealed no systemic toxicity in terms of body weight loss and neurotoxicity in contrast to the administration of paclitaxel or vincristine. Interestingly, multidrug-resistant cell lines generated by vincristine-driven selection or transfection with the Mr 170,000 P-glycoprotein encoding cDNA were rendered resistant toward paclitaxel, vincristine, or doxorubicin but not towards D-24851 when compared with the parental cells. Because of its synthetic nature, its oral applicability, its potent in vitro and in vivo antitumoral activity, its efficacy against multidrug-resistant tumors, and the lack of neurotoxicity, D-24851 may have significant potential for the treatment of various malignancies.

Oral fluoropyrimidine-based combination therapy in gastrointestinal cancer.

Significant emphasis has been placed recently on designing more effective fluorouracil (5-FU)-based combination protocols for gastrointestinal cancer. Promising results were seen with 5-FU/leucovorin in combination with irinotecan (Camptosar) or oxaliplatin (Eloxatin), especially in colorectal cancer. Clinical trials of UFT, with or without leucovorin, demonstrate the safety of this regimen and an efficacy comparable to that of bolus 5-FU/leucovorin in the treatment of gastrointestinal tumors. Two large randomized phase III trials of capecitabine (Xeloda) showed that capecitabine also offers a convenient alternative to bolus 5-FU/leucovorin with a superior safety profile and at least equivalent antitumor activity.

Final results of a randomized phase III trial of sequential high-dose methotrexate, fluorouracil, and doxorubicin versus etoposide, leucovorin, and fluorouracil versus infusional fluorouracil and cisplatin in advanced gastric cancer: A trial of the European Organization for Research and Treatment of Cancer Gastrointestinal Tract Cancer Cooperative Group.

PURPOSE: To compare the efficacy and tolerability of etoposide, leucovorin, and bolus fluorouracil (ELF) or infusional fluorouracil plus cisplatin (FUP) with that of the reference protocol of fluorouracil, doxorubicin, and methotrexate (FAMTX) in advanced gastric cancer. PATIENTS AND METHODS: A total of 399 patients with advanced adenocarcinoma of the stomach were randomized and analyzed for toxicity, tumor response, and progression-free and overall survival. Only reviewed and confirmed responses were considered. The analysis of remission was based on assessable patients with documented measurable lesions. The intent-to-treat principle, log-rank test, and Cox regression model were used for the statistical analysis of time-to-event end points. RESULTS: The overall response rate for 245 eligible patients with measurable disease was 9% with ELF, 20% with FUP, and 12% with FAMTX, with no significant differences. One hundred twelve patients were eligible for efficacy in assessable, nonmeasurable disease. No change was observed in 66% of patients treated with ELF, 56% with FUP, and 55% with FAMTX. Two patients achieved a complete tumor regression (one each for ELF and FAMTX). With a median follow-up time of 4.5 years, the median survival times were 7.2 months with ELF, 7.2 months with FUP, and 6.7 months with FAMTX, respectively, with no significant differences. Nonhematologic and hematologic toxicities of ELF, FUP, and FAMTX were acceptable, with neutropenia being the major toxicity for all three regimens. Seven treatment-related deaths occurred (two with FUP and five with FAMTX). CONCLUSION: All three investigated regimens demonstrate modest clinical efficacy and should not be regarded as standard treatment for advanced gastric cancer. New strategies should be considered to achieve a better clinical efficacy in the treatment of advanced gastric cancer.

Ifosfamide-based drug combinations: preclinical evaluation of drug interactions and translation into the clinic.

Ifosfamide is an alkylating antineoplastic agent with documented activity against a variety of solid tumor types, most notably lung cancer, testicular cancer, and sarcoma. Ifosfamide has been included in various drug combination protocols, usually on an empirical basis. To gather more insight into the mechanisms that underlie these drug interactions and to develop guidelines for further improvement of clinical combination protocols, we performed a broad preclinical evaluation program of ifosfamide-based combination regimens using isobologram analysis of drug interactions. In established cisplatin-sensitive and cisplatin-refractory ovarian carcinoma cell lines, a schedule-dependent drug interaction between paclitaxel and activated hydroperoxy-ifosfamide (4-OOH-IF) could be demonstrated. When both drugs were given for 2 hours, simultaneous exposure or the sequence of paclitaxel followed by 4-OOH-IF were additive or synergistic. In contrast, application of 4-OOH-IF before paclitaxel resulted in pronounced antagonism. Based on the sequence-dependent synergistic interactions a phase I trial was initiated with paclitaxel given on day 1 and ifosfamide given on days 2 to 5 in patients with cisplatin-refractory ovarian cancer. Four dose levels were evaluated in 18 patients. The maximum tolerated dose was paclitaxel 175 mg/m2 on day 1 and ifosfamide 2,000 mg/m2 on days 2 to 5, with central nervous system toxicity and nephrotoxicity being dose-limiting. The recommended dose for further evaluation of this combination was paclitaxel 175 mg/m2 on day 1 and ifosfamide 1,500 mg/m2 on days 2 to 5. Although all patients were heavily pretreated with multiple agents, nine of 18 patients achieved an objective response. Ifosfamide also has been shown to reduce cellular glutathione content; thus, a series of experiments evaluated the ability of activated cyclophosphamide or ifosfamide to deplete cellular glutathione in vitro. It was demonstrated that glutathione depletion is dose- and time-dependent, with 4-OOH-IF leading to a more pronounced suppression of cellular glutathione compared with 4-OOH-Cy. The decrease in cellular glutathione content was maximal at 2 hours after drug treatment; however, cellular glutathione levels returned to normal within 24 hours. When 4-OOH-IF was combined in vitro with cisplatin, schedule-dependent interactions again became obvious. The highest antitumor activity was seen when both drugs were given concurrently; sequential application with 4-OOH-IF given before cisplatin resulted in antagonism. Since adequate glutathione levels are necessary for multidrug resistance protein (MRP) function, glutathione depletion might lead to reversal of MRP-mediated drug resistance. Preliminary data showed that 4-OOH-IF significantly decreases glutathione concentrations in MRP-expressing human HT1080/DR4 sarcoma cells, leading to maximum steady-state reduction after a 90-min exposure to 4-OOH-IF. Taken together the data reported here demonstrate that in vitro ifosfamide may potentiate the antitumor activity of a variety of cytotoxic agents and therefore merits further clinical evaluation in drug combinations (eg, taxanes, anthracyclines).

Characterization of protein kinase chk1 essential for the cell cycle checkpoint after exposure of human head and neck carcinoma A253 cells to a novel topoisomerase I inhibitor BNP1350.

Cellular topoisomerase I is an important target in cancer chemotherapy. A novel karenitecin, BNP1350, is a topoisomerase I-targeting anticancer agent with significant antitumor activity against human head and neck carcinoma A253 cells in vitro. As a basis for future clinical trials of BNP1350 in human head and neck carcinoma, in vitro studies were carried out to investigate its effect on DNA damage and cell cycle checkpoint response. The treatment of A253 cells with BNP1350 caused biphasic profiles of DNA fragmentation displayed from 0 to 48 h after 2-h exposure. Pulsed-field gel electrophoresis demonstrated that the first wave of DNA damage was mainly megabase DNA fragmentation, but the second wave of DNA damage was 50- to 300-kb DNA fragmentation in addition to megabase DNA damage. The cell cycle checkpoint response was characterized after exposure to 0.07 and 0.7 microM concentrations of BNP1350, the IC(50) and IC(90) values, respectively. After exposure to a low concentration of BNP1350 (IC(50)), A253 cells accumulated primarily in G(2) phase. In contrast, treatment with a high concentration of BNP1350 (IC(90)) resulted in S phase accumulation. The concentration-associated cell cycle perturbation by BNP1350 was correlated with different profiles of cell cycle-regulatory protein expression. When treated with the low concentration of BNP1350, cyclin B/cdc2 protein expression was up-regulated, whereas with the high concentration, no significant change was observed at 24 and 48 h. In addition, increased phosphorylation of a G(2) checkpoint kinase chk1 was observed when cells were treated with a low concentration of BNP1350, whereas only slight inhibition of chk1 activity was found in the cells treated with the higher concentration. Altered chk1 phosphorylation after DNA damage appears to be associated with specific phases of cell cycle arrest induced by BNP1350. Because A253 cells do not express the p53 protein, the drug-induced alterations of the G(2) checkpoint kinase chk1 are not p53-dependent.

Reversal of MDR1-associated resistance to topotecan by PAK-200S, a new dihydropyridine analogue, in human cancer cell lines.

Recent data suggest that expression of the membrane P170-glycoprotein (P-gp) may confer resistance to the topoisomerase-I-interactive agent topotecan. The present study describes the cellular effects of a new dihydropyridine analogue, PAK-200S, on P-gp-mediated resistance to topotecan in human breast and ovarian tumour cells. PAK-200S at a non-cytotoxic concentration of 2.0 microM completely reversed resistance to topotecan in P-gp-expressing MCF-7/adr (breast) and A2780/Dx5 (ovarian) tumour cells, respectively, with no effects on parental cells. Cellular pharmacokinetic studies by reversed-phase high-performance liquid chromatography analysis showed significantly lower cellular drug concentrations of the pharmacologically active closed-ring lactone of topotecan in multidrug-resistant cells than in parental cells. PAK-200S was effective in restoring the cellular lactone concentrations of topotecan in resistant MCF-7/adr cells to levels comparable to those obtained in parental cells. Furthermore, exposure of MCF-7/adr cells to topotecan in the presence of PAK-200S significantly increased the induction of protein-linked DNA breaks. PAK-200S did not alter nuclear topoisomerase I-mediated ex vivo pBR322 DNA plasmid unwinding activity and topoisomerase-I protein expression. These results suggest that reversal of P-gp-mediated resistance to topotecan by PAK-200S was related to the restoration of cellular drug concentrations of the active lactone form of topotecan rather than a direct effect on topoisomerase-I function.

Phase I study of a weekly schedule of irinotecan, high-dose leucovorin, and infusional fluorouracil as first-line chemotherapy in patients with advanced colorectal cancer.

PURPOSE: To determine the maximum-tolerated dose (MTD) of a weekly schedule of irinotecan (CPT-11), leucovorin (LV), and a 24-hour infusion of fluorouracil (5-FU24h) as first-line chemotherapy in advanced colorectal cancer and to assess preliminary data on the antitumor activity. PATIENTS AND METHODS: Twenty-six patients with measurable metastatic colorectal cancer were entered onto this phase I study. In the first six dose levels, fixed doses of CPT-11 (80 mg/m2) and LV (500 mg/m2) in combination with escalated doses of 5-FU24h ranging from 1.8 to 2.6 g/m2 were administered on a weekly-times-four (dose levels 1 to 4) or weekly-times-six (dose levels 5 to 6) schedule. The dose of CPT-11 was then increased to 100 mg/m2 (dose level 7). RESULTS: Seventy-nine cycles of 5-FU24h/LV with CPT-11 were administered in an outpatient setting. No dose-limiting toxicities were observed during the first cycle at dose levels 1 to 6, but diarrhea of grade 4 (National Cancer Institute common toxicity criteria) was observed in three patients after multiple treatment cycles. Other nonhematologic and hematologic side effects, specifically alopecia and neutropenia, did not exceed grade 2. With the escalation of CPT-11 to 100 mg/m2 (dose level 7), diarrhea of grade 3 or higher was observed in four of six patients during the first cycle; thus, the MTD was achieved. Sixteen of 25 response-assessable patients (64%; 95% confidence interval, 45% to 83%) achieved an objective response. CONCLUSION: The recommended doses for further studies are CPT-11 80 mg/m2, LV 500 mg/m2, and 5-FU24h 2.6 g/m2 given on a weekly-times-six schedule followed by a 1-week rest period. The addition of CPT-11 to 5-FU24h/LV seems to improve the therapeutic efficacy in terms of tumor response with manageable toxicity.