Effects of SN-38 (an active metabolite of CPT-11) on responses of human and rodent cells to irradiation

Phase II NCCTG trial of RT + irinotecan and adjuvant BCNU plus irinotecan for newly diagnosed GBM

Irinotecan has radiosensitizing effects and shows synergism with nitrosoureas. We performed a Phase II study of RT and irinotecan, followed by BCNU plus irinotecan in newly-diagnosed GBM. The MTD for patients receiving enzyme-inducing anticonvulsants (EIAC) was as follows: irinotecan 400 mg/m(2)/week on Days 1, 8, 22 and 29 during RT, followed by BCNU 100 mg/m(2) Day 1, and irinotecan, 400 mg/m(2) on Days 1, 8, 22 and 29, every 6 weeks. The MTD for non-EIAC patients was as follows: irinotecan 125 mg/m(2)/week on Days 1, 8, 22 and 29 during RT, followed by BCNU 100 mg/m(2) Day 1 and irinotecan 75 mg/m(2) Days 1, 8, 22 and 29, every 6 weeks. Median OS was 10.8 mos. (95% CI: 7.7-14.9); OS at 12 months was 44.6% (95% CI: 33.3-59.8) and PFS 6 was 28.6% (95% CI: 18.9-43.2). Patients went off treatment due to adverse events (7%), refusal (11%), progressive disease (48%), death (9%), and other (9%); 16% completed protocol treatment. Survival was similar in patients with variant (6/7 or 7/7) and wild-type (6/6) UGT1A1*28 genotypic alleles. Grade 3-4 toxicity was more common in non-EIAC patients with variant alleles. SN-38 C(max) and AUC in EIAC patients receiving 400 mg/m(2) irinotecan were 20.9 ng/ml and 212 ng/ml h, and in non-EIAC patients receiving 125 mg/m(2), 15.5 ng/ml and 207 ng/ml h. SN-38 AUC varied by UGT1A1*28 status in non-EIAC patients. This regimen was not significantly active and radiosensitization was not observed. Non-EIAC patients with UGT1A1*28 variant alleles appear particularly sensitive to toxicity from irinotecan.

Treatment of Fluorouracil-Refractory Patients With Liver Metastases From Colorectal Cancer by Using Yttrium-90 Resin Microspheres Plus Concomitant Systemic Irinotecan Chemotherapy

Purpose

Liver metastases are the principal cause of death in patients with advanced colorectal cancer (CRC). Irinotecan is a chemotherapeutic agent used in the treatment of CRC and has demonstrated synergistic potential when used with radiation. Radioembolization with yttrium-90 microspheres has demonstrated increased response and survival rates when given with fluorouracil chemotherapy. This study's goal was to evaluate the maximum-tolerated dose of concomitant irinotecan and radioembolization in fluorouracil-refractory patients with CRC hepatic metastases.

Patients and Methods

Twenty-five irinotecan-naïve patients who had experienced relapse after previous chemotherapy were enrolled onto three dose-escalating groups. Irinotecan was administered at 50, 75, or 100 mg/m2 on days 1 and 8 of a 3-week cycle for the first two cycles, and full irinotecan doses (ie, 100 mg/m2) were administered during cycles 3 to 9. Radioembolization was administered during the first chemotherapy cycle.

Results

Most patients experienced acute, self-limiting abdominal pain and nausea. Mild lethargy and anorexia were common. Grades 3 to 4 events were seen in three of six patients at 50 mg/m2 (obstructive jaundice, thrombocytopenia, diarrhea), in five of 13 patients at 75 mg/m2 (neutropenia, leukopenia, thrombocytopenia, elevated alkaline phosphatase, abdominal pain, ascites, fatigue) and in four of six patients at 100 mg/m2 (diarrhea, deep vein thrombosis, constipation, leukopenia). Eleven (48%) of 23 patients had a partial response, and nine patients (39%) had stable disease. The median progression-free survival was 6.0 months; the median survival was 12.2 months.

Conclusion

Concomitant use of radioembolization plus irinotecan did not reach a maximum-tolerated dose. The recommended dose of irinotecan in this setting is 100 mg/m2 on days 1 and 8 of a 3-week cycle.

Phase I study of induction chemotherapy and concomitant chemoradiotherapy with irinotecan, carboplatin, and paclitaxel for stage III non-small cell lung cancer

BACKGROUND

The aim of this study was to determine the maximum tolerated dose (MTD), dose limiting toxicities (DLTs), and determine the phase II dose for the combination of irinotecan-carboplatin-paclitaxel given as induction chemotherapy and with concomitant chest radiotherapy for patients with Stage III non-small cell lung cancer.

METHODS

Patients with Cancer and Leukemia Group B performance status of 0 to 2, stage IIIA and IIIB NSCLC patients with resectable or unresectable disease were treated with induction chemotherapy (irinotecan 100 mg/m2, carboplatin AUC 5, and paclitaxel 175 mg/m2 days 1 and 22) followed by concomitant chemotherapy (irinotecan, carboplatin, and paclitaxel) and chest radiotherapy (66 Gy for unresectable and 50 Gy for resectable disease) beginning on week 7. The primary objective was to escalate the dose of irinotecan during chemoradiation in sequential cohorts to determine the DLT and MTD of the regimen.

RESULTS

Thirty-eight patients were enrolled (median age 63 years, 57% male, 41% performance status 0, 30% resectable). Induction chemotherapy was tolerable and active (response rate 26%; stable disease 60%). Eight patients did not receive concurrent chemoradiotherapy because of progressive disease (5), death (1), hypersensitivity reaction to paclitaxel (1), and withdrawal of consent (1). Twenty-nine patients received concurrent chemoradiotherapy. The concomitant administration of chest radiotherapy with weekly irinotecan, carboplatin, and paclitaxel was not feasible at the first, second, and third dose levels. DLT was failure to achieve recovery to <or= grade 1 absolute neutrophil count by the day of scheduled chemotherapy administration. Dose de-escalation to irinotecan 30 mg/m2, paclitaxel 40 mg/m2 (with omission of carboplatin) delivered on weeks 2, 3, 5, and 6 of radiotherapy was the MTD. After induction chemotherapy, partial responses, stable disease, and progressive disease was observed in 26%, 60%, and 14% of patients, respectively. After chemoradiotherapy, partial responses were attained in 16 (55%) patients, whereas 12 patients (41%) attained disease stabilization. Median overall survival was 21 months for the entire cohort. Resectable patients had a median survival of 24 months, whereas unresectable patients had a median survival of 19 months. Differences in overall and progression-free survival rates between resectable and unresectable patients was not statistically significant (p = 0.52 and p = 0.90, respectively).

DISCUSSION

Carboplatin, paclitaxel, and irinotecan with concurrent chemoradiotherapy was poorly tolerated as a result of neutropenia. Although dose de-escalation was required for delivery of the regimen, the response rates and survival outcomes were comparable to other similar regimens.

Novel chemotherapeutic agents for the treatment of glioblastoma multiforme

During the last few decades, the discovery of novel targets for therapeutic intervention led to the development of chemotherapeutic agents that specifically interfere with altered cellular functions of tumour cells. Genetic alterations in glioblastoma affect cell proliferation and cell cycle control, as well as invasive and metastatic growth. Therefore, innovative therapeutic strategies have been based on drugs targeting cellular proliferation, invasion, angiogenesis, metastasis and differentiation of tumour cells. Furthermore, disruption of cell-death pathways also contributes to the pathogenesis of glioblastoma and may result in resistance to chemotherapy and radiation. Therefore, additional treatment strategies that target intracellular survival and/or apoptotic pathways are under current laboratory investigation. The progress in the understanding of glioblastoma tumour biology and the refined diagnosis of individual patients together with the exploration of targeted drugs may allow a risk-adapted, individualised therapeutic strategy and will hopefully improve prognosis of glioblastoma patients in the future.

Irinotecan in the treatment of glioma patients: current and future studies of the North Central Cancer Treatment Group

Other than nitrosoureas (carmustine and lomustine) and temozolomide, no agents have consistently demonstrated clinically meaningful benefits for patients with gliomas. The active metabolite of irinotecan, 7-ethyl-10-hydroxy camptothecin (SN-38), exhibited promising antitumor effects in preclinical glioma models. Clinical trials using weekly or every 3 weeks dosing of irinotecan have been completed. Toxicity consisted primarily of mild to moderate neutropenia and diarrhea with both schedules, with occasional severe toxicity including one death from neutropenia and infection. Preliminary analyses have suggested imaging responses in 10-15% of patients. Preclinical models and our understanding of the mechanism of action suggest that irinotecan may sensitize glioma cells to the cytotoxic actions of radiation therapy and alkylating agents; clinical trials designed to assess the therapeutic benefit of combination therapy currently are in progress. There is substantial clinical evidence that the concurrent administration of irinotecan with certain anticonvulsants produces reduced exposure to SN-38. In the absence of anticonvulsants, there is also substantial interpatient variability in drug exposure, perhaps reflecting inherited differences in drug metabolism. Finally several mechanisms of tumor cell resistance to irinotecan have been hypothesized, but the clinical significance of these observations has not been confirmed. Correlative studies to address these pharmacokinetic, pharmacogenetic, and drug resistance questions are ongoing.

Antitumoral effect of irinotecan (CPT-11) on an experimental model of malignant neuroectodermal tumor

Irinotecan (CPT-11) is a topoisomerase I inhibitor with antitumor activity on a wide variety of neoplasms in several preclinical studies, but it showed poor efficacy in patients with nervous system tumors. We have carried out an experimental study in order to evaluate the effect of CPT-11 on the growth of a subcutaneously implanted malignant neuroectodermal tumor, after administration by different routes. The results showed that CPT-11 administration by intraperitoneal injections (at dose 10 mg/kg, 5 days per week, for 2 weeks, followed by 7-days rest period--one course--to a total of two courses) had no significant antitumor effect. Nevertheless, continuous infusion by intraperitoneal osmotic minipump over 28 days (at an infusion rate of 4.4 microg/h) showed a significant delay in tumor growth in 4 weeks of the implantation. The best antitumor effects were observed after CPT-11 intratumoral administration (at dose of 5 mg/kg, 5 days per week, for 2 weeks, followed by 7-days rest period, to a total of three courses) reaching tumor regression in the treated animals. These results suggest the utility of CPT-11, by means of intralesional administration, on malignant tumors of the nervous system.

Evaluation of cell survival, DNA double strand breaks, and DNA synthesis during concurrent camptothecin and X-radiation treatments

We evaluated cell survival, DNA double strand breaks (dsbs), and DNA synthesis following camptothecin (CPT) alone or concurrent CPT and X-radiation treatments in exponential-phase cultures of a radioresistant human melanoma cell line. Cell survival was measured by a clonogenic assay. DNA dsbs were measured by pulsed-field gel electrophoresis. DNA synthesis was measured by incorporation of (3)H-thymidine. We found that (i) concurrent CPT and X-radiation interacted additively, unlike previous results with plateau-phase cultures of these cells, which showed synergistic interaction; (ii) there were strong negative correlations (correlation coefficients of at least 0.82) between clonogenic surviving fractions and DNA dsbs following CPT alone or concurrent CPT and radiation treatments; and (iii) concurrent CPT and radiation (10 Gy) treatment did not completely inhibit DNA synthesis, even though addition of radiation to CPT did further decrease DNA synthesis (relative to CPT alone) at CPT concentrations below 20 microM. Our results suggest that during concurrent CPT and radiation treatment residual DNA dsb levels were good indicators of cell killing and that the absence of complete inhibition of DNA synthesis could at least in part explain the additive interaction between CPT and radiation.