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PubMed1997

Disposition of irinotecan and SN-38 following oral and intravenous irinotecan dosing in mice.

The present study was conducted to quantitate the disposition of irinotecan lactone and its active metabolite SN-38 lactone in mice following oral and intravenous administration, and to evaluate the systemic exposure of irinotecan lactone and SN-38 lactone associated with antitumor doses of irinotecan lactone in mice bearing human tumor xenografts. Nontumor-bearing mice were given a single oral or intravenous irinotecan dose (5, 10, 40, or 75 mg/kg), and serial plasma samples were subsequently obtained. Irinotecan and SN-38 lactone plasma concentrations were measured using an isocratic HPLC assay with fluorescence detection. The disposition of intravenous irinotecan lactone was modeled using a two-compartment pharmacokinetic model, and the disposition of oral irinotecan and SN-38 lactone was modeled with noncompartmental methods. Irinotecan lactone showed biphasic plasma disposition following intravenous dosing with a terminal half-life ranging between 1.1 to 3 h. Irinotecan lactone disposition was linear at lower doses (5 and 10 mg/kg), but at 40 mg/kg irinotecan lactone clearance decreased and a nonlinear increase in irinotecan lactone AUC was observed. The steady-state volume of distribution ranged from 19.1 to 48.1 l/m2. After oral dosing, peak irinotecan and SN-38 lactone concentrations occurred within 1 h, and the irinotecan lactone bioavailability was 0.12 at 10 mg/kg and 0.21 at 40 mg/kg. The percent unbound SN-38 lactone in murine plasma at 1000 ng/ml was 3.4 +/- 0.67%, whereas at 100 ng/ml the percent unbound was 1.18 +/- 0.14%. Irinotecan and SN-38 lactone AUCs in micebearing human neuroblastoma xenografts were greater than in nontumor-bearing animals. Systemic exposure to unbound SN-38 lactone in nontumor-bearing animals after a single oral irinotecan dose of 40, 10, and 5 mg/kg was 28.3, 8.6, and 2.9 ng h/ml, respectively. Data from the present study provide important information for the design of phase I studies of oral irinotecan.

Administration, Oral↗
PubMed2000

Irinotecan plus fluorouracil and leucovorin for metastatic colorectal cancer. Irinotecan Study Group.

BACKGROUND: The combination of fluorouracil and leucovorin has until recently been standard therapy for metastatic colorectal cancer. Irinotecan prolongs survival in patients with colorectal cancer that is refractory to treatment with fluorouracil and leucovorin. In a multicenter trial, we compared a combination of irinotecan, fluorouracil and leucovorin with bolus doses of fluorouracil and leucovorin as first-line therapy for metastatic colorectal cancer. A third group of patients received irinotecan alone. METHODS: Patients were randomly assigned to receive irinotecan (125 mg per square meter of body-surface area intravenously), fluorouracil (500 mg per square meter as an intravenous bolus), and leucovorin (20 mg per square meter as an intravenous bolus) weekly for four weeks every six weeks; fluorouracil (425 mg per square meter as an intravenous bolus) and leucovorin (20 mg per square meter as an intravenous bolus) daily for five consecutive days every four weeks; or irinotecan alone (125 mg per square meter intravenously) weekly for four weeks every six weeks. End points included progression-free survival and overall survival. RESULTS: Of 683 patients, 231 were assigned to receive irinotecan, fluorouracil, and leucovorin; 226 to receive fluorouracil and leucovorin; and 226 to receive irinotecan alone. In an intention-to-treat analysis, as compared with treatment with fluorouracil and leucovorin, treatment with irinotecan, fluorouracil, and leucovorin resulted in significantly longer progression-free survival (median, 7.0 vs. 4.3 months; P=0.004), a higher rate of confirmed response (39 percent vs. 21 percent, P<0.001), and longer overall survival (median, 14.8 vs. 12.6 months; P=0.04). Results for irinotecan alone were similar to those for fluorouracil and leucovorin. Grade 3 (severe) diarrhea was more common during treatment with irinotecan, fluorouracil, and leucovorin than during treatment with fluorouracil and leucovorin, but the incidence of grade 4 (life-threatening) diarrhea was similar in the two groups (<8 percent). Grade 3 or 4 mucositis, grade 4 neutropenia, and neutropenic fever were less frequent during treatment with irinotecan, fluorouracil, and leucovorin. Adding irinotecan to the regimen of fluorouracil and leucovorin did not compromise the quality of life. CONCLUSIONS: Weekly treatment with irinotecan plus fluorouracil and leucovorin is superior to a widely used regimen of fluorouracil and leucovorin for metastatic colorectal cancer in terms of progression-free survival and overall survival.

Adult↗
PubMed2004

Cetuximab monotherapy and cetuximab plus irinotecan in irinotecan-refractory metastatic colorectal cancer.

BACKGROUND: The epidermal growth factor receptor (EGFR), which participates in signaling pathways that are deregulated in cancer cells, commonly appears on colorectal-cancer cells. Cetuximab is a monoclonal antibody that specifically blocks the EGFR. We compared the efficacy of cetuximab in combination with irinotecan with that of cetuximab alone in metastatic colorectal cancer that was refractory to treatment with irinotecan. METHODS: We randomly assigned 329 patients whose disease had progressed during or within three months after treatment with an irinotecan-based regimen to receive either cetuximab and irinotecan (at the same dose and schedule as in a prestudy regimen [218 patients]) or cetuximab monotherapy (111 patients). In cases of disease progression, the addition of irinotecan to cetuximab monotherapy was permitted. The patients were evaluated radiologically for tumor response and were also evaluated for the time to tumor progression, survival, and side effects of treatment. RESULTS: The rate of response in the combination-therapy group was significantly higher than that in the monotherapy group (22.9 percent [95 percent confidence interval, 17.5 to 29.1 percent] vs. 10.8 percent [95 percent confidence interval, 5.7 to 18.1 percent], P=0.007). The median time to progression was significantly greater in the combination-therapy group (4.1 vs. 1.5 months, P<0.001 by the log-rank test). The median survival time was 8.6 months in the combination-therapy group and 6.9 months in the monotherapy group (P=0.48). Toxic effects were more frequent in the combination-therapy group, but their severity and incidence were similar to those that would be expected with irinotecan alone. CONCLUSIONS: Cetuximab has clinically significant activity when given alone or in combination with irinotecan in patients with irinotecan-refractory colorectal cancer.

Adenocarcinoma↗
PubMed1998

Altered irinotecan and SN-38 disposition after intravenous and oral administration of irinotecan in mice bearing human neuroblastoma xenografts.

The antitumor activity of irinotecan in vitro primarily results from its hydrolysis by carboxylesterase to the active metabolite SN-38. The present study was conducted to evaluate the effect of human neuroblastoma xenografts on irinotecan and SN-38 disposition after i.v. and oral irinotecan administration. Non-tumor-bearing mice and mice bearing three different human neuroblastoma xenograft lines (NB1691, NB1643, and NBEB) were given irinotecan (10 mg/kg) by short i.v. injection into the tail vein or by oral gavage. Serial plasma samples were obtained, processed to isolate irinotecan and SN-38 lactone, and assayed with a sensitive and specific high-performance liquid chromatography assay. Noncompartmental and compartmental pharmacokinetic analyses were performed. A four-compartment model was used for analysis of irinotecan and SN-38 concentration-time data after i.v. administration. The presence of tumor increased irinotecan systemic exposure (1.2-3.8-fold; P < 0.05) after i.v. and oral administration in mice bearing neuroblastoma xenografts compared to non-tumor-bearing mice. Moreover, SN-38 systemic exposures were higher (1.3-3.8-fold; P < 0.05) in mice bearing human neuroblastoma xenografts as compared to non-tumor-bearing mice, with the greatest effect observed after oral administration of irinotecan. A schematic model is presented to provide a mechanistic basis for our observations. These results emphasize the need to perform preclinical pharmacokinetic studies to evaluate the influence of tumor on drug disposition.

Administration, Oral↗
PubMed2002

[A case-control study of prevention of irinotecan-induced diarrhea: the reducing side effects of irinotecan by oral alkalization combined with control of defecation].

Irinotecan and its active metabolite, SN-38, were reported to have the absorption characteristics of weakly basic drugs. Moreover, stasis of these compounds is thought to induce damage to the intestinal mucous membrane. The purpose of this report was to examine whether oral alkalization (OA) combined with control of defecation (CD) might prevent irinotecan-induced side effects. From day one of irinotecan infusion to day four, OA & CD were practiced using orally administered sodium bicarbonate, magnesium oxide, basic water, and ursodeoxycholic acid. Thirty-two lung cancer patients were treated with irinotecan in combination with cisplatin in the absence of OA & CD (Group A). Thirty-seven patients matched for background characteristics were treated with the same regimen in the presence of OA & CD (Group B). Group B had a reduced incidence of delayed diarrhea (Grade 2 < or = Group A 32.3% vs. Group B 9.4%), nausea, vomiting, and myelotoxicity, especially granulocytopenia compared with Group A. In addition, dose intensification was well-tolerated in Group B. Tumor response rates for non-small cell lung cancer were 59.3% (16/27 patients) in Group B against 38.5% (10/26 patients) in Group A. OA & CD appears to reduce the irinotecan-induced side effects, especially delayed diarrhea. Risk factors statistically associated with delayed diarrhea include advanced age and the use of irinotecan without OA & CD.

Administration, Oral↗
PubMed2001

Randomized multicenter phase II study comparing a combination of fluorouracil and folinic acid and alternating irinotecan and oxaliplatin with oxaliplatin and irinotecan in fluorouracil-pretreated metastatic colorectal cancer patients.

PURPOSE: To assess antitumor activity and safety of two regimens in advanced colorectal cancer (CRC) patients with proven fluorouracil (5-FU) resistance in a randomized phase II study: 5-FU/folinic acid (FA) combined with alternating irinotecan (also called CPT-11) and oxaliplatin (FC/FO tritherapy), and an oxaliplatin/irinotecan (OC) combination. PATIENTS AND METHODS: Sixty-two patients were treated: arm FC/FO (32 patients) received, every 4 weeks, FA 200 mg/m(2) followed by a 400-mg/m(2) 5-FU bolus injection, then a 600-mg/m(2) continuous infusion of 5-FU on days 1 and 2 every 2 weeks administered alternately with irinotecan (180 mg/m(2) on day 1) and oxaliplatin (85 mg/m(2) on day 15). Arm OC (30 patients) received oxaliplatin 85 mg/m(2) and irinotecan 200 mg/m(2) every 3 weeks. RESULTS: In an intent-to-treat analysis, two partial responses lasting 10.7 and 16 months were observed with the tritherapy regimen, and seven (median duration, 11 months; range, 10.6 to 11.4 months) were observed with the bitherapy regimen. Median progression-free and overall survival times were 8.2 and 9.8 months, respectively, in the FC/FO arm and 8.5 and 12.3 months, respectively, in the OC arm. Main grade 3/4 toxicities were, respectively, neutropenia, 53% and 47%; febrile neutropenia, 13% and 3%; diarrhea, 19% and 10%; vomiting, 6% and 13%; and neurosensory toxicity, 3% and 3%. No treatment-related deaths occurred. CONCLUSION: The every-3-weeks OC combination is safe and active in advanced 5-FU-resistant CRC patients. The lower activity data seen with the tritherapy regimen may be related to the lower dose intensities of irinotecan and oxaliplatin in this schedule.

Adult↗
PubMed2005

Pharmacogenetics of irinotecan: a promoter polymorphism of UGT1A1 gene and severe adverse reactions to irinotecan.

This review focuses on a pharmacogenetic association between genetic polymorphism of UGT1A1 gene and severe adverse reactions to irinotecan. Although many studies used pharmacokinetic parameters as surrogate measures for predicting clinical outcomes of irinotecan chemotherapy, they have not produced consistent evidence. On the other hand, genotyping results of UGT1A1 gene appear to predict severe adverse reactions more straightforward than the pharmacokinetic parameters or the phenotypes of the enzymatic activity. A case-control study of Japanese cancer patients revealed that those with the variant UGT1A1 alleles were at significantly higher risk of severe adverse reactions to irinotecan, suggesting that the genotyping strategy would be clinically useful. Nevertheless, clinical importance of the pharmacogenetic testing should differ for different patient groups and for different clinical situations. We need to keep this issue in mind in applying the pharmacogenetic evidence in clinical practice.

Antineoplastic Agents, Phytogenic↗
PubMed2006

Induction cisplatin-irinotecan followed by concurrent cisplatin-irinotecan and radiotherapy without surgery in oesophageal cancer: multicenter phase II FFCD trial.

A recent phase I study showed that weekly cisplatin, irinotecan and concurrent radiotherapy can be administered with moderate toxicity in patients with oesophageal cancer. Patients with no prior treatment and oesophageal cancer stage I to III, performance status <3, caloric intake >1,500 kcal day(-1) were included. Chemotherapy, with cisplatin 30 mg m(-2) and irinotecan 60 mg m(-2), was administered at days 1, 8, 22, 29, and concurrently with radiotherapy at days 43, 50, 64 and 71. Radiotherapy was delivered with 50 or 50.4 Gy in 25 fractions/5 weeks. Forty-three patients were included, 10 stage I, 19 stage II and 14 stage III. Mean age was 59.2 years (range 44-79). A total of 30 out of 43 (69.8%) patients underwent all planned treatment. During induction chemotherapy, 14 severe toxicities of grade 3 or 4 in 10 patients (23.3%) were reported with 57.1% due to haematoxicity. During chemoradiotherapy, 31 severe toxicities of grade 3 or 4 with 64.5% due to haematotoxicity were reported in 18 patients. One toxic death occurred (diarrhoea grade 4). The complete clinical response rate was 58.1% (95% CI: 43.4-72.8%). Overall survival rate at 1 and 2 years was 62.8%, (95% CI, 58.3-77.3%) and 27.9% (95% CI, 13.4-41.3%), respectively. In conclusion, cisplatin-irinotecan-radiotherapy is an active and well-tolerated regimen feasible in out-patients.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2005

Efficacy and tolerability of oxaliplatin plus irinotecan 5-fluouracil and leucovorin regimen in advanced stage colorectal cancer patients pretreated with irinotecan 5-fluouracil and leucovorin.

OBJECTIVES: Oxaliplatin has been introduced in the treatment of advanced colorectal cancer during the past few years. The pre-existing treatment of leucovorin-5-fluorouracil-irinotecan (IFL), although reasonably effective, has needed novel, active agents to increase the response rate and overall survival. We planned this phase 2 study in patients pretreated with IFL, adding oxaliplatin as second-line treatment: our objectives were to determine response rate and overall survival. METHODS: All patients (median age 65) were designated to receive 6 cycles of chemotherapy: leucovorin 200 mg/m2 infused for 60 minutes, 5-fluorouracil 500 mg/m2 bolus at 30 minutes from the start of the previous infusion, irinotecan 135 mg/m2 infused for 90 minutes, and oxaliplatin 135 mg/m2 for 90 minutes, infused sequentially on day 1 and repeated every 3 weeks. Standard ondansetron antiemetic treatment and dexamethasone 8 mg were administered to all patients. No prophylactic recombinant human granulocyte colony-stimulating factor was permitted. RESULTS: Fifty-seven patients were recruited and 54 were evaluable for response, survival, and toxicity. All patients had advanced, inoperable, metastatic disease in the liver and/or lungs, abdominal cavity, and multiple sites. All patients had undergone IFL pretreatment and had no response; 40 had disease progression and 14 had stable disease when entering the present study; 302 chemotherapy cycles (mean 5.92) were administered. There was no treatment delay caused by toxicity (either neutropenia or diarrhea). Irinotecan and oxaliplatin were reduced by 25% in 6 (11.1%) patients. No complete responses were observed; 21 (38.9%) patients achieved partial response, 26 (48.2%) had stable disease, and 7 (13%) had disease progression. Median duration of response was 6 months, time to tumor progression (TTP) 8 months, and median overall survival after the initiation of second-line treatment was 10 months (95% confidence interval [CI], 7.5-12.6). CONCLUSION: The addition of oxaliplatin to IFL as second-line treatment rendered a prolongation of survival and a response rate of 38.9% in patients in whom IFL pretreatment had failed.

Adenocarcinoma↗
PubMed2006

FOLFOXIRI (folinic acid, 5-fluorouracil, oxaliplatin and irinotecan) vs FOLFIRI (folinic acid, 5-fluorouracil and irinotecan) as first-line treatment in metastatic colorectal cancer (MCC): a multicentre randomised phase III trial from the Hellenic Oncology Research Group (HORG).

To compare the efficacy and toxicity of oxaliplatin (L-OHP) in combination with irinotecan (CPT-11), 5-fluorouracil (5-FU) and leucovorin (LV) (FOLFOXIRI) vs irinotecan and 5-FU/LV (FOLFIRI) as first-line treatment of patients with metastatic colorectal cancer (MCC). A total of 283 chemotherapy-naïve patients with MCC were enrolled (FOLFIRI arm: n=146; FOLFOXIRI arm: n=137). In the FOLFOXIRI arm, CPT-11 (150 mg m(-2)) was given on d1, L-OHP (65 mg m(-2)) on d2, LV (200 mg m(-2)) on days 2 and 3 and 5-FU (400 mg m(-2) as i.v. bolus and 600 mg m(-2) as 22 h i.v. continuous infusion) on days 2 and 3. In the FOLFIRI arm, CPT-11 (180 mg m(-2)) was given on d1 whereas LV and 5-FU were administered in the same way as in the FOLFOXIRI regimen. Both regimens were administered every 2 weeks. There was no difference in terms of overall survival (median OS: 19.5 and 21.5 months, for FOLFIRI and FOLFOXIRI, respectively; P=0.337), median time to disease progression (FOLFIRI: 6.9 and FOLFOXIRI: 8.4 months; P=0.17), response rates (33.6 and 43% for FOLFIRI and FOLFOXIRI, respectively; P=0.168). Patients treated with FOLFOXIRI had a significantly higher incidence of alopecia (P=0.0001), diarrhoea (P=0.0001) and neurosensory toxicity (P=0.001) compared with patients treated with FOLFIRI. The present study failed to demonstrate any superiority of the FOLFOXIRI combination compared with the FOLFIRI regimen, although the observed median OS is one of the best ever reported in the literature.

Adenocarcinoma↗
PubMed2004

Irinotecan plus gemcitabine vs irinotecan for the second-line treatment of patients with advanced non-small-cell lung cancer pretreated with docetaxel and cisplatin: a multicentre, randomised, phase II study.

To compare irinotecan (CPT-11)+gemcitabine vs CPT-11 alone as second-line treatment for patients with advanced non-small cell lung cancer (NSCLC) progressing after docetaxel-cisplatinum-based therapy. A total of 147 evaluable, pretreated patients, with NSCLC, received either gemcitabine (1000 mg m(-2), days 1 and 8)+CPT-11 (300 mg m(-2), day 8) (Group A, n=76) or CPT-11 (300 mg m(-2), day 1) (Group B, n=71), every 3 weeks. All patients were evaluable for response and toxicity. The objective response rate was 18.4% (95% CI: 9.71-27.14%) and 4.2% (95% CI: 0-8.90%) (P=0.009) for groups A and B, respectively. No significant differences between the two groups in terms of the median duration of response, time to tumour progression, overall survival and 1-year survival were observed. The CPT-11/gemcitabine regimen significantly improved the patients' quality of life ('general mood today' (P=0.014), 'coughing' (P=0.003) and 'intensity of symptoms' (P=0.034)) compared with CPT-11. More cycles had to be delayed (P=0.001) and required prophylactic growth factor support (P=0.001) in Group A than B. Three (3.9%) patients in Group A and eight (11.3%) in Group B developed febrile neutropenia (P=0.09); one patient died of sepsis in each group. Three additional (Group A, n=1; Group B, n=2) treatment-related deaths were observed. Grade 3-4 haematologic toxicity was comparable in the two groups except anaemia (P=0.03 in favour of CPT-11). Other nonhaematologic toxicities were mild and similar in the two groups. CPT-11+gemcitabine resulted in a higher response rate and better control of disease-related symptoms than CPT-11 alone, but without any improvement in the overall survival.

Adult↗
PubMedDate not supplied

Chronomodulated irinotecan, oxaliplatin, and leucovorin-modulated 5-Fluorouracil as ambulatory salvage therapy in patients with irinotecan- and oxaliplatin-resistant metastatic colorectal cancer.

PURPOSE: To evaluate the activity and tolerability of salvage chronomodulated chemotherapy combining irinotecan (I), 5-fluorouracil/leucovorin (5-FU/LV), and oxaliplatin (O) (chronoIFLO) in patients with metastatic colorectal cancer (MCRC) and prior progression on four drugs. PATIENTS AND METHODS: Seventy-seven nonhospitalized MCRC patients received chronoIFLO every 3 weeks, with day 1: I (180 mg/m2 over 6 hours, with peak infusion rate at 05:00) and days 2-5: 5-FU/LV (700/300 mg/m2 per day over 12 hours, with peak flow rate at 04:00), and O (20 mg/m2 per day over 12 hours, with peak flow rate at 16:00). Toxicity and response were assessed every 3 weeks and every 2 months, respectively. RESULTS. Three or more prior chemotherapy lines were given to 75% of the patients. Two or more organs had metastatic disease in 65% of the patients. A median number of six courses of chronoIFLO was given. The main grade 3-4 toxicities were diarrhea (39% of the patients, 9% of the courses) and neutropenia (30% of the patients and 7% of the courses). Grade 3 peripheral sensory neuropathy occurred in 14% of the patients. Two patients achieved a partial response and 61 had stable disease, resulting in disease control for 82% of the patients. The median time to progression (TTP) was 5.5 months (95% confidence interval, 3.7-6.0). The median overall survival time was 14.2 months (9.8-17.3). Baseline performance status, serum carcinoembryonic antigen (CEA) level, and CEA doubling time were independent prognostic factors of TTP. CONCLUSIONS: ChronoIFLO safely and durably halted tumor progression in most extensively pretreated MCRC patients.

Adult↗
PubMed2000

Pharmacokinetics of irinotecan and its metabolites SN-38 and APC in children with recurrent solid tumors after protracted low-dose irinotecan.

Irinotecan (IRN), a topoisomerase I interactive agent, has significant antitumor activity in early Phase I studies in children with recurrent solid tumors. However, the disposition of IRN and its metabolites, SN-38 and APC, in children has not been reported. Children with solid tumors refractory to conventional therapy received IRN by a 1-h i.v. infusion at either 20, 24, or 29 mg/m2 daily for 5 consecutive days for 2 weeks. Serial blood samples were collected after doses 1 and 10 of the first course. IRN, SN-38, and APC lactone concentrations were determined by an isocratic high-performance liquid chromatography assay. A linear four-compartment model was fit simultaneously to the IRN, SN-38, and APC plasma concentration versus time data. Systemic clearance rate for IRN was 58.7 +/- 18.8 liters/h/m2 (mean +/- SD). The mean +/- SD ng/ml x h single-day lactone SN-38 area under the concentration-time curve (AUC(0-->6) was 90.9 +/- 96.4, 103.7 +/- 62.4, and 95.3 +/- 63.9 at IRN doses of 20, 24, and 29 mg/m2, respectively. The relative extent of IRN conversion to SN-38 and metabolism to APC measured after dose 1 were 0.49 +/- 0.33 and 0.29 +/- 0.17 (mean +/- SD). No statistically significant intrapatient difference was noted for SN-38 area under the concentration-time curve. Large interpatient variability in IRN and metabolite disposition was observed. The relative extent of conversion and the SN-38 systemic exposure achieved with this protracted schedule of administration were much greater than reported in adults or children receiving larger intermittent doses.

Adolescent↗
PubMedDate not supplied

Biomodulation of cancer chemotherapy for metastatic colorectal cancer: a randomized study of weekly low-dose irinotecan alone versus irinotecan plus the oncostatic pineal hormone melatonin in metastatic colorectal cancer patients progressing on 5-fluorouracil-containing combinations.

Recent advances in immunobiological knowledge have suggested the possibility of enhancing the therapeutic activity of various chemotherapeutic agents by a concomitant administration of anti-oxidant drugs and/or immunomodulating neurohormones. In particular, the pineal neurohormone melatonin (MLT), which is able to exert both antioxidant and immunomodulating effects, has been proven to enhance the efficacy of various chemotherapeutic drugs, namely cisplatin, anthracyclines and 5-fluorouracil, whereas at present there are no data about its possible influence on cytotoxic drugs effective in the treatment of colon cancer other than 5-fluorouracil, such as irinotecan (CPT-11). The present study was performed to evaluate the influence of a concomitant administration of MLT on CPT-11 therapeutic activity in metastatic colorectal cancer. The study included 30 metastatic colorectal cancer patients progressing after at least one previous chemotherapeutic line containing 5-fluorouracil, who were randomized to be treated with CPT-11 alone or CPT-11 plus MLT. According to a weekly low-dose schedule, CPT-11 was given i.v. at 125 mg/m2/week for 9 consecutive weeks. MLT was administered orally at 20 mg/day during the dark period of the day. No complete response was observed. A partial response (PR) was achieved in 2 out of 16 patients treated with CPT-11 alone and in 5 out of 14 patients concomitantly treated with MLT. Moreover, a stable disease (SD) was obtained in 5 out of 16 patients treated with CPT-11 alone and in 7 out of 14 patients treated with CPT-11 plus MLT. Therefore, the percent of disease-control achieved in patients concomitantly treated with MLT was significantly higher than that observed in those treated with chemotherapy alone (12 out of 14 vs 7 out of 16, p < 0.05). The only important toxicity was diarrhoea grade 3-4, which occurred in 6 out of 16 patients treated with CPT-11 alone and in 4 out of 14 patients treated with CPT-11 plus MLT, which required a 50% dose reduction. However, taken together, patients treated with CPT-11 at 50% of the planned dose showed a percent of disease control comparable to that achieved in patients who had no dose reduction (6 out of 10 vs 13 out of 20). This preliminary study shows that the efficacy of weekly low-dose CPT-11 in pretreated metastatic colorectal cancer patients may be enhanced by a concomitant daily administration of the pineal hormone MLT, according to the results previously reported for other chemotherapeutic agents. Moreover, since the dose reduction of CPT-11 does not influence its efficacy, the dose of CPT-11 for successive studies might be not greater than 70 mg/m2.

Adjuvants, Immunologic↗
PubMed1997

Clinical pharmacokinetics of irinotecan.

This article reviews the clinical pharmacokinetics of a water-soluble analogue of camptothecin, irinotecan [CPT-11 or 7-ethyl-10-[4-(1-piperidino)-1-piperidino]-carbonyloxy-camptoth eci n]. Irinotecan, and its more potent metabolite SN-38 (7- ethyl-10-hydroxy-camptothecin), interfere with mammalian DNA topoisomerase I and cancer cell death appears to result from DNA strand breaks caused by the formation of cleavable complexes. The main clinical adverse effects of irinotecan therapy are neutropenia and diarrhoea. Irinotecan has shown activity in leukaemia, lymphoma and the following cancer sites: colorectum, lung, ovary, cervix, pancreas, stomach and breast. Following the intravenous administration of irinotecan at 100 to 350 mg/m2, mean maximum irinotecan plasma concentrations are within the 1 to 10 mg/L range. Plasma concentrations can be described using a 2- or 3-compartment model with a mean terminal half-life ranging from 5 to 27 hours. The volume of distribution at steady-state (Vss) ranges from 136 to 255 L/m2, and the total body clearance is 8 to 21 L/h/m2. Irinotecan is 65% bound to plasma proteins. The areas under the plasma concentration-time curve (AUC) of both irinotecan and SN-38 increase proportionally to the administered dose, although interpatient variability is important. SN-38 levels achieved in humans are about 100-fold lower than corresponding irinotecan concentrations, but these concentrations are potentially important as SN-38 is 100- to 1000-fold more cytotoxic than the parent compound. SN-38 is 95% bound to plasma proteins. Maximum concentrations of SN-38 are reached about 1 hour after the beginning of a short intravenous infusion. SN-38 plasma decay follows closely that of the parent compound with an apparent terminal half-life ranging from 6 to 30 hours. In human plasma at equilibrium, the irinotecan lactone form accounts for 25 to 30% of the total and SN-38 lactone for 50 to 64%. Irinotecan is extensively metabolised in the liver. The bipiperidinocarbonylxy group of irinotecan is first removed by hydrolysis to yield the corresponding carboxylic acid and SN-38 by carboxyesterase. SN-38 can be converted into SN-38 glucuronide by hepatic UDP-glucuronyltransferase. Another recently identified metabolite is 7-ethyl-10-[4-N-(5-aminopentanoic acid)-1-piperidino]-carbonyloxy-camptothecin (APC). This metabolite is a weak inhibitor of KB cell growth and a poor inducer of topoisomerase I DNA-cleavable complexes (100-fold less potent than SN-38). Numerous other unidentified metabolites have been detected in bile and urine. The mean 24-hour irinotecan urinary excretion represents 17 to 25% of the administered dose. Recovery of SN-38 and its glucuronide in urine is low and represents 1 to 3% of the irinotecan dose. Cumulative biliary excretion is 25% for irinotecan, 2% for SN-38 glucuronide and about 1% for SN-38. The pharmacokinetics of irinotecan and SN-38 are not influenced by prior exposure to the parent drug. The AUC of irinotecan and SN-38 correlate significantly with leuco-neutropenia and sometimes with the intensity of diarrhoea. Certain hepatic function parameters have been correlated negatively with irinotecan total body clearance. It was noted that most tumour responses were observed at the highest doses administered in phase I trials, which indicates a dose-response relationship with this drug. In the future, these pharmacokinetic-pharmacodynamic relationships will undoubtedly prove useful in minimising the toxicity and maximise the likelihood of tumour response in patients.

Antineoplastic Agents, Phytogenic↗
PubMed1998

Pharmacology of irinotecan.

Irinotecan (CPT-11) is a semisynthetic derivative of camptothecin, an alkaloid extracted from the Chinese plant Camptotheca acuminata. It bears a bis-piperidine moiety and was selected for its water solubility and promising preclinical antitumor activity in in vitro and in vivo models. The target of drugs of the camptothecin family is DNA topoisomerase I, a nuclear enzyme involved in the relaxation of the DNA double helix required for replication and transcription activities. They stabilize the enzyme-DNA complex and prevent the religation of the single-strand breaks created by the enzyme, which are converted to double-strand breaks upon the collision with a replication fork during the S-phase. Resistance to irinotecan appears not to be mediated by P-glycoprotein, but by qualitative and/or quantitative alterations of its target, topoisomerase I, or by alterations occurring downstream of this interaction. As with all camptothecin derivatives, irinotecan contains a lactone ring that can be spontaneously and reversibly hydrolyzed to a carboxylate open ring form, which predominates at neutral and alkaline pH and is inactive on topoisomerase I-DNA complexes. Irinotecan is, in fact, much less active than its metabolite SN-38 and is generally considered as a prodrug of this compound. The carboxylesterase which carries out this conversion is preferentially active on the lactone form of irinotecan and directly generates the lactone form of SN-38, which may explain the superiority of irinotecan over SN-38 in vivo. Further metabolism of SN-38 to a beta-glucuronide conjugate is a major pathway of detoxification and plays an important role in determining irinotecan toxicity in the clinical setting. Other metabolic pathways of irinotecan involve oxidations occurring on the bis-piperidine rings, which are carried out by cytochrome P450. Irinotecan has shown an important activity in advanced and metastatic colorectal carcinoma and is now used for this indication in several countries, with two different recommended schedules: weekly administration of 125 mg/m(2) with a 2-week drug-free interval every 4 administrations or 3-weekly administration of 350 mg/m(2), a dose that can be increased to 500 mg/m(2) with the support of antidiarrhetics. Other possible indications of irinotecan include lung and cervix cancer, which are presently under investigation. The dose-limiting toxicity of irinotecan is mainly diarrhea, which occurs 7-10 days after treatment and can be life-threatening when associated with neutropenia, another frequent side effect. High-dose loperamide has shown good efficacy for treating this diarrhea and has allowed an increase in irinotecan doses tolerated by patients. The pharmacokinetics of irinotecan are characterized by a 2- or 3-compartment decay, with a terminal half-life of about 10 h, a total volume of distribution of 150 l/m(2) and a total plasma clearance of 15 l/h/m(2). SN-38 AUC is only a small fraction of that of irinotecan (2-4%) and SN-38 is eliminated from plasma with a half-life of about 12 h. SN-38 glucuronide is present in plasma at higher concentrations than SN-38 and is eliminated at the same rate. APC, produced by the action of cytochrome P450, isoenzyme 3A4, is present in plasma at concentrations close to those of irinotecan itself. Only a small fraction of irinotecan and its metabolites is eliminated in urine and a higher proportion in the bile, with an enterohepatic cycle of SN-38 glucuronide and SN-38. Significant relationships have been established between the AUCs of both irinotecan and SN-38 and hematological and intestinal toxicities, suggesting a potential use for monitoring of this drug.

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