Irinotecan (CPT-11) high-dose escalation using intensive high-dose loperamide to control diarrhea.

BACKGROUND: Diarrhea is a serious side effect that may prevent the administration of high doses of the antitumor drug Irinotecan (CPT-11). PURPOSE: Intensive, high-dose loperamide was used in an attempt to control or downstage CPT-11-induced diarrhea and thus permit the use of higher dose intensities of CPT-11. METHODS: Twenty-three patients with various cancers were treated with doses of CPT-11 ranging from 400 to 600 mg/m2, administered as a 30-minute intravenous infusion every 3 weeks. Starting 8 hours or more after the administration of CPT-11, any episode of diarrhea was treated with 2 mg of loperamide taken every 2 hours. Patients stopped taking loperamide only after a 12-hour diarrhea-free period. If diarrhea was not controlled after 3 consecutive days of nonstop loperamide intake, or if the patient was dehydrated, loperamide was stopped and the patient was hospitalized for intravenous fluids. If blood or mucus were found in the stools at any time during diarrhea, loperamide was stopped and the patient was hospitalized. RESULTS: Seventeen of 23 patients had diarrhea while on CPT-11 treatment. Eighty-two CPT-11 cycles were administered to these 17 patients, and diarrhea occurred in 49 of these cycles, at a median time-to-onset of 6 days after CPT-11 administration. The loperamide protocol was followed in 46 of the 49 episodes of diarrhea, with 21 capsules of loperamide the median number being taken (range, 5-72). Only one patient was hospitalized for failure to respond to loperamide, and no major toxicity was associated with loperamide use. Fourteen of the 17 patients who experienced diarrhea were rechallenged with CPT-11 three or more times, and seven patients six or more times. CONCLUSIONS: High-dose loperamide controlled diarrhea in patients receiving CPT-11 and allowed administration of higher doses of CPT-11. IMPLICATIONS: The effectiveness of CPT-11 might be increased by higher dose intensities, which can be made tolerable by control of diarrhea with loperamide.

Phase I and pharmacologic studies of the camptothecin analog irinotecan administered every 3 weeks in cancer patients.

PURPOSE: A phase I study was undertaken to determine the maximum-tolerated dose (MTD), principal toxicities, and pharmacokinetics of the novel topoisomerase I inhibitor irinotecan (CPT-11). PATIENTS AND METHODS: Sixty-four patients meeting standard phase I eligibility criteria were included (24 women, 40 men; median age, 51 years; primary sites: colon, head and neck, lung, pleura; 60 of 64 had been previously treated). Pharmacokinetics was determined by high-performance liquid chromatography (HPLC). RESULTS: One hundred ninety CPT-11 courses were administered as a 30-minute intravenous (IV) infusion every 3 weeks (100 to 750 mg/m2). Grade 3 to 4 nonhematologic toxicities included diarrhea (16%; three hospitalizations), nausea and vomiting (9%), asthenia (14%), alopecia (53%), elevation of hepatic transaminases (8%), and one case of skin toxicity. An acute cholinergic syndrome was observed during CPT-11 administration. Diarrhea appeared dose-limiting at 350 mg/m2, but this was circumvented by using a high-dose loperamide protocol that allowed dose escalation. Dose-dependent, reversible, noncumulative granulocytopenia was the dose-limiting toxicity (nadir, days 6 to 9; median recovery time, 5 days). Grade 3 to 4 anemia was observed in 9% of patients. One patient died during the study, 8 days after CPT-11 treatment. Two complete responses (cervix, 450 mg/m2; head and neck, 750 mg/m2) and six partial responses in fluorouracil (5-FU)-refractory colon cancer were observed (260 to 600 mg/m2). Pharmacokinetics of CPT-11 and active metabolite SN-38 were performed in 60 patients (94 courses). CPT-11 plasma disposition was bi- or triphasic, with a mean terminal half-life of 14.2 +/- 0.9 hours (mean +/- SEM). The mean volume of distribution (Vdss) was 157 +/- 8 L/m2, and total-body clearance was 15 +/- 1 L/m2/h. The CPT-11 area under the plasma concentration versus time curves (AUC) and SN-38 AUC increased linearly with dose. SN-38 plasma decay had an apparent half-life of 13.8 +/- 1.4 hours. Both CPT-11 and SN-38 AUCs correlated with nadir leukopenia and granulocytopenia, with grade 2 diarrhea, and with nausea and vomiting. CONCLUSION: The MTD of CPT-11 administered as a 30-minute IV infusion every 3 weeks is 600 mg/m2, with granulocytopenia being dose-limiting. At 350 mg/m2, diarrhea appeared dose-limiting, but high-dose loperamide reduced this toxicity and allowed dose escalation. For safety reasons, the recommended dose is presently 350 mg/m2 every 3 weeks; more experience must be gained to establish the feasibility of a higher dose in large multicentric phase II studies. However, when careful monitoring of gastrointestinal toxicities is possible, a higher dose of 500 mg/m2 could be recommended in good-risk patients. The activity of this agent in 5-FU-refractory colorectal carcinoma makes it unique and mandates expedited phase II testing.

High dose-intensity of irinotecan administered every 3 weeks in advanced cancer patients: a feasibility study.

PURPOSE: To assess, on a multicenter basis, the feasibility of treating advanced cancer patients with high-dose irinotecan. PATIENTS AND METHODS: Thirty-five patients who met the usual phase I criteria (26 men and nine women) were included. Primary tumor sites were colon, head and neck, unknown primary, kidney, liver, and others. All had been previously treated. Irinotecan was given at the maximum-tolerated dose (MTD) (600 mg/m2) or the level below (500 mg/m2) as a 30-minute infusion once every 3 weeks. RESULTS: Eighteen patients were entered in the four participating centers at the MTD of 600 mg/m2. This dose level was clearly shown not to be feasible: 14 patients (78%) had grade 3 to 4 neutropenia, with febrile episodes in 11 patients; grade 3 to 4 diarrhea was observed in nine patients; and one toxic death occurred. Subsequently, 17 not heavily pretreated patients were included at 500 mg/m2 and carefully monitored. The safety of this dose level was considered acceptable: 41% of patients had grade 3 to 4 neutropenia, 24% experienced grade 3 to 4 diarrhea, and no febrile granulocytopenia or toxic death occurred. Six partial responses were documented in metastatic colorectal cancer, all in patients who had previously received conventional chemotherapy, four in patients who had exhibited progressive disease under fluorouracil (5FU)-based chemotherapy. CONCLUSION: We plan to study the higher dose-intensity 500-mg/m2 level on good-risk and carefully monitored patients. This could enlarge the spectrum of tumors sensitive to irinotecan and improve the already good results observed in colorectal cancers.

Etoposide bioavailability after oral administration of the prodrug etoposide phosphate in cancer patients during a phase I study.

PURPOSE: The purpose of this study was to determine the bioavailability (F) of etoposide (E;VP-16) after oral administration of the water-soluble prodrug etoposide phosphate (EP;BMY-40481) during a phase I trial in cancer patients. PATIENTS AND METHODS: Twenty-nine patients received oral EP (capsules, 50 to 150 mg/m2/d of E equivalent) for 5 days in week 1 (course 1), followed every 3 weeks thereafter by a daily intravenous (i.v.) infusion for 5 days of E (80 mg/m2, 1-hour i.v. infusion; course 2); in three patients, the i.v. E course was given before oral EP. Plasma and urine E pharmacokinetics (high-performance liquid chromatography [HPLC]) were performed on the first day of oral EP administration and on the first day of i.v. E. RESULTS: Twenty-six of 29 patients completed two courses or more, whereas three patients received only one course due to toxicity. Myelosuppression was dose-dependent and dose-limiting, with grade 4 leukoneutropenia in four of 15 patients at 125 mg/m2 and in five of seven patients at 150 mg/m2. One patient died of meningeal hemorrhage related to grade 4 thrombocytopenia. Other toxicities were infrequent and/or manageable. No objective response was observed. The maximum-tolerated dose (MTD) is therefore 150 mg/m2, and the recommended oral dose of EP for phase II trials in this poor-risk patient population is 125 mg/m2. Twenty-six patients had pharmacokinetic data for both oral EP and i.v. E, whereas three had pharmacokinetic data on the i.v. E course only. After oral administration of EP, the pharmacokinetics of E were as follows: mean absorption rate constant (Ka), 1.7 +/- 1.7 h-1 (mean +/- SD); lag time, 0.3 +/- 0.2 hours; time of maximum concentration (t(max)), 1.6 +/- 0.8 hours; and mean half-lives (t1/2), 1.6 +/- 0.2 (first) and 10.3 +/- 5.8 hours (terminal); the increase in the area under the plasma concentration-versus-time curve (AUC) of E was proportional to the EP dose. After the 1-hour i.v. infusion of E, maximum concentration (C(max)) was 15 +/- 3 micrograms/mL; mean AUC, 88.0 +/- 22.0 micrograms.h/mL; mean total-body clearance (CL), 0.97 +/- 0.24 L/h/m2 (16.2 mL/min/m2); and mean t1/2, 0.9 +/- 0.6 (first) and 8.1 +/- 4.1 hours (terminal). The 24-hour urinary excretion of E after i.v. E was significantly higher (33%) compared with that of oral EP (17%) (P < .001). Significant correlation was observed between the neutropenia at nadir and the AUC of E after oral EP administration (r = .58, P < .01, sigmoid maximum effect [E(max)] model). The mean F of E after oral administration of EP in 26 patients was 68.0 +/- 17.9% (coefficient of variation [CV], 26.3%; F range, 35.5% to 111.8%). In this study, tumor type, as well as EP dose, did not significantly influence the F in E. There was no difference in F of E, whether oral EP was administered before or after i.v. E. Compared with literature data on oral E, the percent F in E after oral prodrug EP administration was 19% higher at either low ( < or = 100 mg/m2) or high ( > 100 mg/m2) doses. CONCLUSION: Similarly to E, the main toxicity of the prodrug EP is dose-dependent leukoneutropenia, which is dose-limiting at the oral MTD of 150 mg/m2/d for 5 days. The recommended oral dose of EP is 125 mg/m2/d for 5 days every 3 weeks in poor-risk patients. Compared with literature data, oral EP has a 19% higher F value compared with oral E either at low or high doses. This higher F in E from oral prodrug EP appears to be a pharmacologic advantage that could be of potential pharmacodynamic importance for this drug.

CPT-11 (irinotecan) in the treatment of colorectal cancer.

Colorectal cancer is one of the most common cancers in the Western World. Although 50% of patients are cured by surgery alone, the outcome is poor in high-risk patients (Dukes stages B2 and C) despite adjuvant chemotherapy with 5-fluorouracil (5-FU)-based regimens. CPT-11 (irinotecan) is a promising new agent for the treatment of colorectal cancer with a unique mechanism of action. CPT-11 is a DNA topoisomerase I inhibitor, which has not demonstrated susceptibility to the P-glycoprotein-mediated multidrug-resistant phenotype. Phase II studies with CPT-11 have demonstrated definite activity against colorectal cancer in both chemotherapy-naive and pretreated patients (response rates of 15-32% observed) even with clinical evidence of resistance to 5-FU. The response rate appears to be consistent, reproducible and equivalent to that achieved with 5-FU plus folinic acid in chemotherapy-naive patients.

Rationale for the dosage and schedule of CPT-11 (irinotecan) selected for phase II studies, as determined by European phase I studies.

BACKGROUND: CPT-11 (irinotecan), a camptothecin-derived anticancer agent with DNA topoisomerase 1 inhibitory activity, has demonstrated a broad spectrum of in vitro and in vivo activity in solid tumour models including multidrug-resistant tumours. This review details the rationale for the dosage schedule of CPT-11 selected for phase II studies, based on the results of 3 European phase I dose-escalating trials in patients with solid tumours. PATIENTS AND METHODS: CPT-11 was administered as a 30-minute intravenous infusion once every 3 weeks (schedule 1), once daily for 3 consecutive days every 3 weeks (schedule 2) or once weekly every 3 out of 4 weeks (schedule 3). RESULTS: Neutropenia and diarrhoea were the major dose-limiting toxicities in all of the studies. The maximum tolerated dose of CPT-11 was 115 and 145 mg/m2/day for schedules 2 and 3, respectively. With schedule 1, diarrhoea became dose-limiting at 350 mg/m2 but was manageable with high-dose loperamide therapy. CONCLUSIONS: CPT-11 350 mg/m2 administered as an intravenous infusion once every 3 weeks was chosen for further evaluation in early phase II studies, since this dosage regimen allowed the highest dose intensity with the least toxicity and was convenient for outpatient use. The place of higher doses (with intensive antidiarrhoeal support) and other administration schedules (e.g., protracted infusion) warrant further investigation.

Phase I and pharmacology study of intoplicine (RP 60475; NSC 645008), novel topoisomerase I and II inhibitor, in cancer patients.

Intoplicine (RP 60475F; NSC 645008) is a novel 7H-benzo[e]pyrido[4,3-b]indole derivative which interacts with both topoisomerases I and II. Because of its high activity in preclinical cancer models, original mechanism of action and acceptable toxicity profile, intoplicine was further evaluated in a phase I and pharmacology study. Thirty-three (33) patients (24 men and nine women) meeting standard phase I eligibility criteria were included: median age was 56 years, performance status 0-1 in 28 patients and 2 in five patients. Tumor primary sites were head and neck (9), colon (6), lung (3) and various other sites (15). Thirty-one patients had received prior radiotherapy and/or chemotherapy. Sixty-nine coursed of intoplicine were administered as a 1 h i.v. infusion at dose levels ranging from 12 to 360 mg/m2. Dose-dependent and reproducible hepatotoxicity was dose limiting in three out of four patients at 360 mg/m2: this toxicity was reversible in two of three patients, but fatal in one. Two sudden deaths occurred in this study at 12 and 48 mg/m2, and the drug implication could not be excluded. No myelosuppression was noted. Hepatotoxicity is therefore dose limiting at 360 mg/m2, and the phase II recommended dose is 270 mg/m2 every 3 weeks with close monitoring of hepatic and cardiac functions. Intoplicine pharmacokinetics was determined in plasma (23 patients) and whole blood (18 patients) at doses ranging from 12 to 360 mg/m2. Intoplicine plasma concentration decay was either bi- or triphasic with the following pharmacokinetic values (mean +/- SEM): half-life alpha, 0.04 +/- 0.004 h; half-life beta, 0.61 +/- 0.13 h; terminal half-life, 19.4 +/- 4.0 h; mean residence-time (MRT), 11.3 +/- 2.4; total plasma clearance (CL), 74 +/- 5 l/h; volume of distribution beta (V beta), 1982 +/- 477 l: volume of distribution at steady state (Vss): 802 +/- 188 l. both the area under the plasma concentration versus time curves (AUC) and the maximum plasma concentrations (Cmax) increased linearly with the intoplicine dose, indicating linear pharmacokinetics (AUC: r = 0.937; slope = 0.01305; p < 0.001; Cmax: r = 0.847; slop = 0.01115; p < 0.001). Plasma AUC was also predicted very accurately by the Cmax values (r = 0.909; slope = 1.0701; p < 0.001). Other plasma pharmacokinetic parameter values increased significantly with dose, e.g. the terminal half-life (r = 0.748, p < 0.001) the MRT (r = 0.728, p < 0.001), the V beta (r = 0.809, p < 0.001), and the Vss (r = 0.804, p < 0.001). This was probably due to a longer detectability of the drug in plasma at higher doses. Blood pharmacokinetics was also evaluated in 18 patients since it was found that red blood cells represented a significant drug reservoir for intoplicine. Blood intoplicine disposition curves were either bi- or triphasic with the following pharmacokinetic parameter values (mean +/- SEM): half-life alpha, 0.04 +/- 0.01 h; half-life beta, 0.94 +/- 0.22 h; terminal half-life, 57.1 +/- 6.6 h; MRT, 82.2 +/- 9.9 h; CL, 18 +/- 3 l/h; V beta, 1188 +/- 147 I; Vss 1163 +/- 138 I. Blood pharmacokinetics was linear, since AUC and Cmax increased linearly with dose (AUC: r = 0.879; slop = 0.06884; p < 0.001; Cmax: r = 0.835, slop = 0.01223; p < 0.001). Blood AUC values could also be determined by the blood Cmax (r = 0.768; slop = 5.0206; p < 0.001). Other blood pharmacokinetic parameter values presented a dose dependence, e.g. the terminal half-life (r = 0.626, p = 0.005), the V beta (r = 0.682, p = 0.002) and the Vss (r = 0.555, p = 0.017). The plasma or blood intoplicine concentrations achieved in vivo in humans are potentially cytotoxic levels based on preclinical in vivo and in vitro data. In conclusion, the phase II recommended dose of intoplicine is 270 mg/m2 administered as a 1 h i.v. infusion every 3 weeks. Plasma and blood pharmacokinetics were linear within the dose range studied. Potentially cytotoxic concentrations were reached at clinically achievable doses.

Population pharmacokinetics and pharmacodynamics of irinotecan (CPT-11) and active metabolite SN-38 during phase I trials.

BACKGROUND: Irinotecan (CPT-11) is a novel water-soluble camptothecin derivative selected for clinical testing based on its good in vitro and in vivo activity in various experimental systems, including pleiotropic drug-resistant tumors. Its mechanism of action appears mediated through topoisomerase I inhibition. The purpose of this study was to describe CPT-11 and active metabolite SN-38 population pharmacokinetics, examine patient characteristics that may influence pharmacokinetics, and to investigate pharmacokinetic-pharmacodynamic relationships that may prove useful in the future clinical management of this drug. PATIENTS AND METHODS: As part of 3 Phase I studies including 235 patients, pharmacokinetics of CPT-11 and metabolite SN-38 were determined in 107 patients. CPT-11 was administered as a 30-min i.v. infusion according to 3 different schedules: daily for 3 consecutive days every 3 weeks, weekly for 3 weeks, and once every 3 weeks. Patients characteristics were the following: median age 53 years; 62 men, 45 women; 105 caucasians, 2 blacks; performance status was 0-1 in 96 patients; tumor sites were predominantly colon, rectum, head and neck, lung, ovary and breast; with the exception of 6 patients, all had been previously treated with surgery, chemotherapy and/or radiotherapy. CPT-11 and metabolite SN-38 were simultaneously determined by HPLC using fluorescence detection. Pharmacokinetic parameters were determined using model-independent and model-dependent analyses. RESULTS: 168 pharmacokinetic data sets were obtained in 107 patients (97 first courses, 43 second courses, 23 third courses, 4 fourth courses, and 1 fifth course). Rebound concentrations of CPT-11 were frequently observed at about 0.5 to 1 h following the end of the i.v. infusion, which is suggestive of enterohepatic recycling of the drug. Model-independent analysis yielded the following mean population pharmacokinetic parameters for CPT-11: a terminal half-life of 10.8 h, a mean residence time (MRT) of 10.7 h, a volume of distribution at steady state (Vdss) of 150 L/m2, and a total body clearance of 14.3 L/m2/h. Model-dependent analysis disclosed a CPT-11 plasma disposition as either biphasic or triphasic with a mean terminal half-life of 12.0 h. The volume of distribution Vdss (150 L/m2) and total body clearance (14.8 L/m2/h) yielded almost identical values to the above model-independent analysis. The active metabolite SN-38 presented rebound concentrations in many courses at about 1 h following the end of the i.v. infusion which is suggestive of enterohepatic recycling. The mean time at which SN-38 maximum concentrations was reached was at 1 h since the beginning of the 0.5 h infusion (i.e., 0.5 h post i.v.). SN-38 plasma decay followed closely that of the parent compound with a mean apparent terminal half-life of 10.6 h. Mean 24 h CPT-11 urinary excretion represented 16.7% of the administered dose, whereas metabolite SN-38 recovery in urine was minimal (0.23% of the CPT-11 dose). The number of CPT-11 treatments did not influence pharmacokinetic parameters of either the parent compound or metabolite SN-38. Although CPT-11 pharmacokinetics presented an important interpatient variability, both CPT-11 maximum concentrations (Cmax) and the CPT-11 area under the plasma concentration versus time curves (AUC) increased proportionally and linearly with dosage (Cmax, r = 0.78, p < 0.001); CPT-11 AUC, r = 0.88, p < 0.001). An increase in half-life and MRT was observed at higher dosages, although this did not influence the linear increase in AUC as a function of dose. The volume of distribution at steady state (Vdss) and the total body clearance (CL) were not affected by the CPT-11 dose. Metabolite SN-38 AUC increased proportionally to the CPT-11 dose (r = 0.67, p < 0.001) and also with the parent compound AUC (r = 0.75, p < 0.001) (ABSTRACT TRUNCATED)