Phase II study of CPT-11, a new camptothecin derivative, in metastatic colorectal cancer. CPT-11 Gastrointestinal Cancer Study Group

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.

Review of the role of CPT-11 in the treatment of colorectal cancer

Colorectal cancer (CRC) is the second leading cause of cancer death in Western countries, and although the treatment of advanced CRC has progressed substantially, the improvements in response rates have not always been translated into a significant survival benefit. Until recently, the standard therapy for advanced CRC was a variety of biomodulated 5-fluorouracil (5-FU) regimens. 5-FU was used as first- or second-line therapy, and a different 5-FU regimen was used second line if first-line 5-FU therapy failed. Typically, the survival times for these patients were short and their quality of life poor. In recent years, a variety of new agents have emerged that have demonstrated activity in the treatment of advanced CRC. Of these, irinotecan (CPT-11) and oxaliplatin in combination with 5-FU and folinic acid (FA) have yielded the most promising results. However, only CPT-11 combined with either bolus or high-dose infusional 5-FU/FA, in randomized phase III studies, has demonstrated an increased response rate and median time to progression, producing a significant and clinically relevant survival advantage. In 2 randomized phase III studies, oxaliplatin/5-FU/FA demonstrated a clear increase in response rate over 5-FU/FA alone but failed to demonstrate a survival advantage. CPT-11 was approved by the Food and Drug Administration in April 2000 for the first-line treatment of advanced CRC in combination with 5-FU/FA.

The role of irinotecan in colorectal cancer

Irinotecan, also known as CPT-11, is a topoisomerase I inhibitor currently approved for use as a second-line agent in the treatment of advanced colorectal cancer. Preliminary reports from randomized studies exploring combinations of CPT-11 plus 5-fluorouracil have shown improved antitumor activity versus 5-fluorouracil-based treatments alone, and suggest a first-line role for these combination regimens. The role of CPT-11/5-fluorouracil regimens in the adjuvant setting is now being actively explored. Studies of single-agent CPT-11 in the first-line treatment of metastatic colorectal cancer have shown activity; however response rates do not appear to be superior to those seen with standard first-line 5-fluorouracil-based regimens. The use of specific molecular markers as prognostic indicators of response or resistance to specific chemotherapies may, however, permit the identification of a selected population of patients with tumor characteristics that would specifically favor consideration of up-front use of single-agent CPT-11.

Phase I-II study of irinotecan in combination with mitomycin C in patients with advanced gastrointestinal cancer

This phase I-II study was conducted to determine the maximum tolerated dose and optimal schedule of a combination of irinotecan (CPT 11) and mitomycin C (MMC) in a population of previously treated patients with gastrointestinal malignancies. Four cohorts of patients were recruited with MMC given at 8 mg/m2 for the first 3 levels together with irinotecan at 300 mg/m2, 325 mg/m2, and 350 mg/m2; the fourth dose level was given with MMC at 10 mg/m2 and irinotecan at 325 mg/m2. All treatment was repeated at 21-day intervals. The dose-limiting toxicity was hematologic (thrombocytopenia at level 4), and the recommended doses for subsequent phase II studies are MMC 8 mg/m2 with irinotecan 325 mg/m2. Evidence of efficacy was seen at all dose levels examined and justifies further exploration of this combination in a less heavily pretreated patient population.

New therapies, new directions: advances in the systemic treatment of metastatic colorectal cancer

Colorectal cancer is the second leading cause of cancer death and it is clear that patients with metastatic disease have better quality of life and survival when given treatment. Despite four decades of experience of treating patients with fluorouracil, there remains considerable controversy about the optimum dose and scheduling, as well as biomodulation with leucovorin and methotrexate. However, irrespective of the dose and schedule, overall survival times are poor--about 1 year. Disappointingly, oral agents with similar mechanisms to fluorouracil do not improve survival rates in comparison with fluorouracil and leucovorin treatment. Irinotecan and oxaliplatin are newer agents that have improved the response rates for patients with metastatic disease when they are added to flurouracil and leucovorin. The combination of irinotecan, fluorouracil, and leucovorin has also improved overall survival. These are small advances in the fight against colorectal cancer, and further drug development is necessary.

Advances in the treatment of metastatic colorectal cancer

Colorectal cancer represents the third leading cause of cancer mortality in the United States. During the past four decades, 5-fluorouracil (5-FU) has served as the cornerstone of therapy for individuals with advanced colorectal cancer (ACRC). Despite numerous attempts at maximizing efficacy of 5-FU through biochemical modulation, a significant benefit in terms of survival has never been realized. The recent emergence of novel chemotherapeutic drugs employing different mechanisms of action than 5-FU has led to the incorporation of irinotecan (CPT-11) with 5-FU/leucovorin as the new standard first-line regimen for future trials. This review outlines emerging data utilizing oral fluoropyrimidines and other new agents including oxaliplatin, raltitrexed, and eniluracil. Randomized clinical trials are currently underway in an effort to define optimal combination chemotherapy regimens, scheduling of agents, duration of therapy, and choice of therapy using a variety of prognostic molecular markers.

Irinotecan plus fluorouracil/leucovorin for metastatic colorectal cancer: a new survival standard

BACKGROUND

Irinotecan is a topoisomerase I inhibitor that prolongs survival in patients with colorectal cancer refractory to fluorouracil (5-FU) and leucovorin (LV). This demonstrated activity of irinotecan as effective second-line therapy for colorectal cancer led to evaluation of combination irinotecan/5-FU/LV as first-line therapy for patients with metastatic disease. The results of two prospective phase III randomized, controlled, multicenter, multinational clinical trials in patients with previously untreated metastatic colorectal cancer served as the basis for U.S. and European approval of irinotecan/5-FU/LV for this indication. An overview of the findings of these two pivotal studies provides insights regarding the application of this new combination in clinical practice.

METHODS

Patients were randomly assigned to receive 5-FU/LV, either alone, or with concurrent irinotecan. The study conducted primarily in North America (study 1), employed bolus 5-FU/LV schedules, while the study performed primarily in Europe (study 2), employed infusional 5-FU/LV regimens. Major endpoints included tumor response rate, time to tumor progression (TTP), overall survival, quality of life, and safety.

RESULTS

In study 1, the respective confirmed response rates for irinotecan/5-FU/LV versus 5-FU/LV were 39% and 21% (p <.001); median TTPs were 7.0 months and 4.3 months, respectively (p =.004). In study 2, response rates for irinotecan/5-FU/LV versus 5-FU/LV alone were 35% and 22% (p =.005); median TTPs were 6.7 months and 4.4 months, respectively (p <.001). Survival time increased significantly with irinotecan/5-FU/LV versus 5-FU/LV alone in both studies (study 1: median 14.8 months versus 12.6 months, p =.042; study 2: median 17.4 months versus 14.1 months, p =.032). The combined analysis of the data from the two studies showed median survivals of 15.9 months versus 13.3 months, favoring the irinotecan-containing combinations (stratified-by-study p =.003). Patients in study 1 had a 36% lower risk of tumor progression and a 20% lower risk of death with the irinotecan combination than with 5-FU/LV alone; comparable risk reduction values in study 2 were 42% and 23%. While grade 3 diarrhea and vomiting were more common with irinotecan/5-FU/LV, grade 4 neutropenia, neutropenic fever, and mucositis were less common with irinotecan/5-FU/LV than with the Mayo Clinic 5-FU/LV regimen.

CONCLUSION

The combination of irinotecan/5-FU/LV is superior to 5-FU/LV alone as first-line therapy for patients with metastatic colorectal cancer, offering consistently improved tumor control and prolonged survival. Irinotecan-based combination therapy sets a new survival standard for the treatment of this life-threatening disease.

A phase II trial of irinotecan (CPT-11) for unresectable biliary tree carcinoma

BACKGROUND

Unresectable adenocarcinomas of the biliary tree have a very poor prognosis. No good chemotherapeutic regimen is available. Irinotecan has not yet been fully tested in this disease. We evaluated its activity in unresectable bile duct cancers.

PATIENTS AND METHODS

Twenty-five consecutive eligible patients at our two institutions were treated with irinotecan at a starting dose of 125 mg/m2. A cycle consisted of once-a-week treatments for four consecutive weeks, followed by two weeks of rest. All patients were required to have histologically confirmed diagnosis, clinically documented metastatic or unresectable carcinoma and measurable disease. Patients were evaluated for response, toxicity, and survival.

RESULTS

A total of 83 cycles of therapy were delivered. Two patients had a partial response (8%; 95% confidence interval (CI): 0%-18%) and ten additional patients had stable disease for at least two months (40%; 95% CI: 20.8%-59.2%). The therapy was well tolerated, with moderate myelosuppression and diarrhea as the main toxicities. The overall median survival was 10 months.

CONCLUSIONS

Irinotecan has minimal activity in biliary tree carcinomas, but is well tolerated with appropriate supportive care, and produces occasional objective responses.

Pulmonary resection for metastases from colorectal cancer

BACKGROUND

We reviewed our experience in the surgical treatment of 47 patients with colorectal pulmonary metastases and investigated factors affecting their survival.

METHOD

From September 1986 to December 1999, 47 patients underwent 59 thoracotomies for pulmonary metastases from colorectal cancer.

RESULTS

The median interval between colorectal resection and lung resection (disease-free interval [DFI]) was 33 months. Overall, 5-year survival was 48%. Five-year survival was 51% for patients with solitary metastasis (n = 30), 47% for patients with ipsilateral multiple metastases (n = 11), and 50% for patients with bilateral metastases (n = 6), and there were no significant differences. Five-year survival was 80.8% for 14 patients with DFI of < 2 years and 39.7% for 30 patients with a DFI of > 2 years (p = 0.22). Five-year survival for 11 patients with normal prethoracotomy carcinoembryonic antigen (CEA) levels was 70%, and that for 26 patients with elevated prethoracotomy CEA levels (> 5 ng/mL) was 36% (p < 0.05). Eight patients had extrathoracic disease. The median survival time after pulmonary resection was 18.5 months, and the 5-year survival was 60%. A second resection for recurrent metastases was performed in five patients, and a third resection was done in one patient. All six patients are alive. The median survival of five patients who underwent a second thoracotomy was 22 months (range, 2 to 68 months), and one patient is alive 39 months after the third resection.

CONCLUSION

Pulmonary resection for metastases from colorectal cancer may help prolong survival in selected patients, even with bilateral lesions, recurrent metastasectomy, or extrathoracic disease. Prethoracotomy CEA level was found to be a significant prognostic factor.

Phase II trial of 9-aminocamptothecin (NSC 603071) administered as a 120-hr continuous infusion weekly for three weeks in metastatic colorectal carcinoma

9-Aminocamptothecin (9-AC) is a camptothecin derivative with broad antitumor activity in preclinical studies. Prior investigations suggested that prolonged maintenance of 9-AC lactone plasma concentrations above 10 nmol/l and frequent administration of the drug are important determinants of antitumor activity. Our phase II study, therefore, examined a 5-day continuous infusion of 9-AC weekly for 3 weeks in patients with advanced colorectal cancer. Eighteen patients previously untreated for metastatic disease received 480 microg/m2/day of 9-AC. No responses were observed in 17 evaluable patients. Severe toxicities included granulocytopenia, nausea, vomiting and diarrhea. The median absolute granulocyte count (AGC) nadir was 2,300/microl (range 0-9,000/microl) and occurred on day 10. Eight patients received an escalated dose of 600 microg/m2/day. The median AGC nadir at the escalated dose was 1,500/microl (range: 300-2,700/microl) and occurred on day 22. The median number of courses given was 2 (range: 1-8); and the median time to disease progression was 8 weeks (range: 1-40 weeks). 9-AC administered by this schedule lacked antitumor activity in patients with advanced colorectal carcinomas.

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.

Prospective phase II trial of iriontecan, 5-fluorouracil, and leucovorin in combination as salvage therapy for advanced colorectal cancer

Irinotecan (CPT11) has established activity in the treatment of advanced colorectal cancer without cross-resistance with established 5-fluorouracil/folinic acid-based therapy. This phase II study was conducted to establish the efficacy and tolerance of combination treatment with irinotecan and 5-fluorouracil as salvage treatment for this disease. Open phase II trial of CPT11 180 mg/m2 on day 1, leucovorin 200 mg/m2 on days 1 and 2, and 5-fluorouracil 400 mg/m2 loading dose followed by 600 mg/m2 infusion on days 1 and 2. Treatment was continued until progression or limiting toxicity. Responders could proceed to surgical resection of residual disease. Thirty-nine patients from 2 institutions received a total of 287 cycles of therapy (median 7 cycles/patient). Eight patients achieved an objective response (7 for liver metastasis and 1 for lung metastasis), and an additional 12 obtained stabilization of disease or minor responses (MR); of these patients, 8 with liver metastasis (7 partial response and 1 MR) underwent hepatic resection of metastases and all them obtained a complete response. The median duration of response was 14 months, and the median survival was 11 months. Hematologic toxicity (neutropenia) was the most common serious side effect (29% of patients in 2% of cycles), but significant fever developed in only 4 patients. Grade III diarrhea was experienced in at least 1 cycle by 10% of patients. The results of this schedule compare favorably with previously reported experience of a phase I study designed to establish the dose of CPT11. Efficacy in this poor prognosis group of patients is very encouraging, and the schedule is well tolerated by even previously treated patients.

Schedule specific biochemical modulation of 5-fluorouracil in advanced colorectal cancer: a randomized study. GISCAD, IOR and collaborating centers

BACKGROUND

We have recently suggested that bolus 5-fluorouracil (5-FU) may work via a RNA directed mechanism while continuous infusion 5-FU may kill cells via a thymidylate synthase related pathway. It may thus be possible to selectively modulate each schedule biochemically. We have compared an alternating regimen of bolus and continuous infusion 5-FU, selectively modulated for the schedule of administration, with modulated bolus 5-FU in advanced colorectal cancer patients.

PATIENTS AND METHODS

Two hundred fourteen patients from nineteen Italian centers were randomized to the control arm consisting of biweekly cycles of MTX, 200 mg/m2 on day 1, followed by bolus 5-FU 600 mg/m2 on day 2 and 6-S-leucovorin rescue, or to the experimental arm consisting of two biweekly cycles of the same regimen as in the control arm alternated to three weeks of continuous infusion 5-FU (200 mg/m2 day) + weekly bolus 6-S-leucovorin, 20 mg/m2.

RESULTS

Nine CR and twenty-seven PR were obtained on one hundred eleven evaluable patients treated in experimental arm (RR = 32%, 95% confidence interval (95% CI): 24%-42%), while two CR and eleven PR were observed among one hundred three evaluable patients in control arm (RR = 13%, 95% CI: 7%-21%). WHO grade 3-4 toxicity occurred in 13% of cycles of experimental arm and in 8% of cycles in control arm. The PFS was significantly longer in experimental arm (6.2 vs. 4.3 months, odds ratio 0.66, P = 0.003), while the overall survival was similar in both arms (14.8 months in experimental arm vs. 14.1 months in control arm); quality of life was similar as well. Eighty percent of patients receiving second-line chemotherapy in control arm were treated with continuous infusion 5-FU.

CONCLUSIONS

Alternating, schedule-specific biochemical modulation of FU is more active than MTX --> 5-FU as first-line treatment of advanced colorectal cancer. However, the overall survival was similar suggesting that alternating bolus and infusional 5-FU upfront may be as effective as giving them in sequence as first- and second-line treatment.

Clinical use of topoisomerase I inhibitors in anticancer treatment

The camptothecin analogs topotecan and irinotecan have shown to be among the most effective anticancer agents and, as S-phase specific agents, their antitumor effect is maximized when they are administered in protracted schedules. The documented activity as single agents in many adult and pediatric malignancies has been followed by their use in combination with other anticancer agents. These studies have shown promising results, and have placed topotecan and irinotecan in the first line treatment for some malignancies. However, studies to better determine the optimal schedules and sequence of combinations are needed.

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.

Phase I and pharmacologic study of docetaxel and irinotecan in advanced non-small-cell lung cancer

PURPOSE

We conducted a phase I trial of docetaxel, a new antimicrotubule agent, combined with irinotecan (CPT-11), a topoisomerase I inhibitor. The aim was to determine the maximum-tolerated dose (MTD) of docetaxel combined with CPT-11, as well as the dose-limiting toxicities (DLTs) of this combination in advanced non-small-cell lung cancer (NSCLC) patients.

PATIENTS AND METHODS

Thirty-two patients with stage IIIB or IV NSCLC were treated at 4-week intervals with docetaxel (60 minutes, day 2) plus CPT-11 (90 minutes, days 1, 8, and 15). The starting doses of docetaxel/CPT-11 were 30/40 mg/m(2), and doses were escalated in 10-mg/m(2) increments until the MTD was reached.

RESULTS

The MTD of docetaxel/CPT-11 was 50/60 mg/m(2) (level 5A), or 60/50 mg/m(2) (level 5B). Neutropenia and diarrhea were the DLTs. CPT-11 did not affect the pharmacokinetics of docetaxel. There were 11 (37%) partial responses among 30 patients. The median survival time was 48 weeks, and the 1-year survival rate was 44.9%.

CONCLUSION

The combination of docetaxel and CPT-11 seems to be active against NSCLC, with acceptable toxicity. The recommended dose for phase II studies is 50 mg/m(2) of CPT-11 (days 1, 8, and 15) and 50 mg/m(2) of docetaxel (day 2) administered every 28 days.

Nuclear scintigraphic assessment of intestinal dysfunction after combined treatment with 9-amino-20(S)-camptothecin (9-AC) and irradiation

PURPOSE

The camptothecins (CPTs) are potent radiosensitizers of malignant tumors in vivo. The extent of normal tissue damage after combined CPT and radiation treatment is unknown. In this article, a jejunal absorption assay with (99m)Tc- pertechnetate (Na[(99m)TcO(4)]) was used to assess C3H/Kam mice given total body irradiation (TBI) of 4 Gy, 6 Gy, and 8 Gy, 2 mg/kg single intramuscular injection of 9-AC or a combination of 2 mg/kg 9-AC + 4 Gy TBI. We also correlated the absorption data with morphologic changes in the jejunal mucosa.

MATERIALS AND METHODS

((99m)TcO(4))(-) absorption from the intestinal lumen into the circulation was studied with dynamic gamma-scintigraphy combined with a multichannel analyzer to record the radiometry data in a time-dependent fashion. Jejunal cross sections were scored for the number of cells per villus and the percentage of apoptotic and mitotic cells in the crypt compartment. The jejunal microcolony assay was used to quantify jejunal crypt survival.

RESULTS

A dose-dependent decrease in the absorption function was observed 3.5 days following TBI. The mean absorption rate was reduced to 89 +/- 16% of control in response to a sublethal 4 Gy TBI and dropped to 47. 5 (9.8% in response to 8 Gy TBI. The mean rate of intestinal absorption was delayed by single sublethal 2 mg/kg 9-AC injection to 62 (11% in comparison with control values. The combination of a single 4 Gy TBI with a 9-AC treatment decreased the ((99m)TcO(4))(-) jejunal absorption in an additive fashion producing absorption lifetime values more than twofold longer than controls. The decrease in ((99m)TcO(4))(-) absorption at 3.5 days after irradiation, 9-AC treatment or the combination of the two agents correlates with the number of cells per villus and the percentage of apoptotic cells in the crypt compartment.

CONCLUSION

Dynamic enteroscintigraphy with (99m)Tc-pertechnetate is a sensitive functional assay for rapid evaluation of radiation and chemotherapy induced intestinal damage. Reduced intestinal absorptive function has a cellular basis and correlates directly with the numbers of cells lost per villus in a treatment-dependent manner.

In vitro augmentation of antitumor effect in combination with CPT-11 and CDDP for human colorectal cancer

BACKGROUND AND OBJECTIVES

Irinotecan hydrochloride (CPT-11) is one of the camptothecin analogues that has shown a broad spectrum of strong antitumor effectiveness against various cancers, including colorectal cancer. In order to promote the clinical response of chemotherapy for colorectal cancer using CPT-11, one of the most effective strategies is to use it in combination with other anticancer agents. In the present study, anticancer effects after combining CPT-11 and other antitumor agents were determined by a 3-(4,5-di-methylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay of colorectal cancer cells, especially freshly isolated cancer cells.

METHODS

Freshly isolated cancer cells from 20 patients with colorectal cancer and the established colon cancer cell lines were used in this study. The augmentation of the antitumor effectiveness of 7-ethyl-10-hydroxy-CPT (SN-38) was analyzed in combination with other anticancer agents. Furthermore, the antitumor effectiveness using lower concentrations of anticancer agents was measured to understand the mechanism of the augmentation.

RESULTS

The percent inhibition of SN-38 in combination with cisplatin (CDDP) and mitomycin revealed a high anticancer effect compared with each anticancer agent alone for freshly isolated rectal cancer. CDDP also had a synergistic effect in combination with SN-38 according to the fractional product concept. At lower than plasma peak concentrations of SN-38, the anticancer effects were augmented in combination with lower concentrations of CDDP for freshly isolated colorectal cancer. This augmentation showed a strong synergistic effect.

CONCLUSIONS

These results may be supportive to ongoing clinical studies of chemotherapy by using CPT-11 and CDDP for advanced colorectal cancer.

A dose-escalation phase II clinical trial of infusional mitomycin C for 7 days in patients with advanced measurable colorectal cancer refractory or resistant to 5-fluorouracil

Chemotherapy for 5-fluorouracil (5-FU)-resistant colorectal cancer is largely ineffective with new and innovative therapeutic strategies needed to benefit patients developing progressive disease while receiving 5-FU or 5-FU-based programs. The tumor antibiotic mitomycin C is an alkylating agent with a broad range of clinical activity in a variety of gastrointestinal malignancies and is therefore a reasonable agent to test for clinical activity in the setting of 5-FU-resistant or -refractory colorectal cancer. The principal goal of this study is to investigate the logistical feasibility and clinical efficacy of a 7-day infusion of mitomycin C, delivering an equitoxic dose to the standard bolus delivery in patients with progressive disease while receiving 5-FU-based chemotherapy. Twenty-five patients with advanced measurable colorectal cancer, resistant or refractory to 5-FU-based chemotherapy, were treated with a 7-day intravenous infusion of mitomycin C. Doses ranged between 1.5 and 3.0 mg/M2/day for total cumulative mitomycin C, ranging between 10.5 and 21.0 mg/M2 per chemotherapy cycle. Forty-four courses of infusional mitomycin C were delivered to 25 patients via surgically implanted venous access devices. The median age of all patients was 63 years (range, 27-83); there were 11 men and 14 women. Eleven patients had received two or more prior chemotherapy combinations, with the average number of prior therapies before mitomycin C being 1.6. The median number of cycles of mitomycin C administered was two (range, one to six). Thirty-seven of 44 cycles were administered at the dose range of 2.0-3.0 mg/M2/day. Hematologic toxicity was mild, with only three courses associated with grade III thrombocytopenia and one course with grade III neutropenia. No extrahematologic toxicities were observed. No patient had a complete response; two patients (8%) showed partial responses that lasted for 145 and 190 days. One patient had stable disease for 180 days. Twenty-two of 25 patients (88%) developed progressive disease during mitomycin C administration. Infusional mitomycin C for 7 days, cycled every 42 days, is logistically feasible and associated with minimal clinical toxicity. Used on this schedule and with these doses in 5-FU-resistant/refractory colorectal cancer, however, there is no meaningful clinical activity for this agent, and it cannot be recommended as a salvage or second-line therapy in the treatment of metastatic colorectal cancer.

Sequence-dependent growth inhibition and DNA damage formation by the irinotecan-5-fluorouracil combination in human colon carcinoma cell lines

We evaluated irinotecan (CPT-11) together with 5-fluorouracil (5-FU) for improved cell growth inhibition with respect to that by either agent alone in the human colon carcinoma cell lines SW620, HT-29 and SNU-C4. Cells were exposed for 24 h to each drug, as well as to various combinations and sequences of low, fixed doses of one drug with higher varying doses of the other, cultured for two more days in drug-free medium and then assessed for growth response with the sulphorhodamine B assay. Multiple drug effect analysis was used to evaluate the data, which were then related to the amount of DNA damage occurring in the cells which was determined by a fluorescence-enhancement assay for DNA unwinding. Cellular responses were also related to thymidylate synthase topoisomerase I and carboxyl esterase activities, which were assessed by a ligand-binding and a 3H-release assay; a DNA decatenation assay; and a spectrophotometric method, respectively. IC50 values for 5-FU alone in the SW620, HT29 and SNU-C4 cells were 15.3 +/- 0.8, 8.2 +/- 1.3 and 2.2 +/- 0.7 microM, respectively, and for CPT-11 2.0 +/- 0.9, 2.5 +/- 0.5 and 3.8 +/- 0.3 microM, respectively. The differential responses to 5-FU alone were possibly determined by differences in substrate affinity and conversion rate of thymidylate synthase (K(m) of approximately 7.5, 5.0 and 2.5 microM and V0 of approximately 800, 200 and 2400 microM/h, respectively). The comparable cellular responses to CPT-11 alone might be accounted for by the counterbalancing effects of differences in topoisomerase I (1, 1, and 1.5 arbitrary units, respectively) and carboxyl esterase activities (5055 +/- 1789, 4080 +/- 752, 1713 +/- 522 mU/mg, respectively). IC20 CPT-11 prior to 5-FU was additive to synergistic in SW620, HT-29 and SNU-C4 cells (CIs of 0.7 +/- 0.1). By contrast, pre-treatment with IC20 5-FU antagonised the CPT-11-mediated growth inhibition (CIs of 1.9 +/- 0.4, 1.7 +/- 1.1, 2.5 +/- 0.9, respectively). Simultaneous drug treatment did not produce more cell growth inhibition than either drug alone in the SW620 and the HT-29 cells, but was additive or antagonistic in the SNU-C4 cells (CIs of 1.1 +/- 0.3 and 2.2 +/- 1.4), depending on the ratio of the drugs. Increased DNA damage in the SW620 and HT-29 cells was only seen when IC20 CPT-11 preceded IC50 5-FU, resulting in approximately 40 and 25%, respectively, more lesions than for IC50 5-FU alone. In the SNU-C4 cells, not only such a treatment, but also simultaneous drug treatment produced (30 to 60%) more DNA damage than either drug alone. Our results show clear sequence-dependent antiproliferative effects and DNA damage formation by CPT-11 and 5-FU at combinations of low, fixed doses with higher, varying doses in cultured human colon carcinoma cells, and may be of relevance to the design of improved chemotherapeutic regimens in this disease.

Irinotecan combined with bolus fluorouracil, continuous infusion fluorouracil, and high-dose leucovorin every two weeks (LV5FU2 regimen): a clinical dose-finding and pharmacokinetic study in patients with pretreated metastatic colorectal cancer

PURPOSE

To determine the maximum-tolerated dose (MTD) and recommended dose of irinotecan (CPT-11) in combination with fluorouracil (5-FU) and leucovorin (LV), using a biweekly LV5FU2 regimen and increasing doses of CPT-11, and to assess the efficacy of this combination in pretreated patients with colorectal cancer (CRC).

PATIENTS AND METHODS

All patients had metastatic CRC and a World Health Organization performance status of 0 or 1. CPT-11 was administered over a 90-minute infusion every 2 weeks at a range of dose levels (100, 120, 150, 180, 200, 220, and 260 mg/m(2)). LV5FU2 was started 1 hour after the end of the biweekly CPT-11 infusion and was also administered on day 2.

RESULTS

Fifty-five patients were entered onto this trial; 549 cycles were administered. The MTD was not reached at 260 mg/m(2), and a dose level of 300 mg/m(2) was added. The MTD as defined in the protocol was not reached at this dose level either, but all patients had cycles delayed and/or required a dose reduction. This dose was deemed to be the MTD. To take into account both the toxicity of and compliance with the biweekly schedule, the recommended CPT-11 dose was established at 180 to 200 mg/m(2). Antitumor activity was observed at almost all dose levels, with an objective response rate of 22%. Median time to progression was 6.3 months and overall survival was 15 months.

CONCLUSION

The biweekly CPT-11/LV5FU2 combination is feasible and safe, without overlapping toxicity. CPT-11 at 180 to 200 mg/m(2) in combination with LV5FU2 has been selected as the recommended dose for further studies.

A review of the pharmacology and clinical activity of new chemotherapy agents for the treatment of colorectal cancer

Colorectal carcinoma is an important cause of cancer morbidity and mortality. 5-fluorouracil has been the major chemotherapeutic agent for the treatment of colorectal carcinoma for the past four decades. This regimen is noncurative, and its impact on survival is unclear. Attempts at identifying more effective chemotherapeutic agents for colorectal cancer have yielded oral formulations and prodrugs of 5-fluorouracil with apparently equivalent efficacy. Specific thymidylate synthase inhibitors are now available. Platinum analogues with activity in colorectal carcinoma, and no cross-resistance to the antimetabolites have also been developed. The topoisomerase I inhibitors represent a new class of agents with a novel mechanism of action. These agents are in phase II and Phase III clinical trials, others have been approved for clinical use within the last 3 years.

Concurrent irinotecan and 5-fluorouracil plus levo-folinic acid given every other week in the first-line management of advanced colorectal carcinoma: a phase I study of the Southern Italy Cooperative Oncology Group

OBJECTIVES

To determine the maximum tolerable doses (MTDs) of irinotecan (CPT-11) and 5-fluorouracil (5-FU) plus levofolinic acid (LFA) administered together every two weeks, to define the toxicity profile of this regimen, and to have a preliminary evidence of its activity in the first-line management of advanced colorectal cancer patients.

PATIENTS AND METHODS

Patients with histologically proven colorectal carcinoma, no prior chemotherapy for their advanced disease, and with at least one measurable or evaluable indicator lesion, were admitted to this study. The starting dose of CPT-11 was 150 mg/m2 given i.v. (90 min infusion) on day 1, followed on day 2 by a fixed dose of LFA (250 mg/m2) as a two-hour i.v. infusion plus a starting dose of 5-FU 600 mg/m2 as i.v. bolus. No intra-patient dose escalation was allowed. If no dose limiting toxicity (DLT) was observed among three patients of each cohort, CPT-11 and 5-FU were alternately escalated in the subsequent cohort. Otherwise, three more patients were enrolled at the same dose level. DLT was defined as: WHO grade 3 non-haematological toxicity (except for vomiting or alopecia), grade 3 febrile neutropenia, grade 4 neutro- or thombocytopenia, or a > 2-week delay in recycling. The MTDs were defined as the doses at which two of three, or four of six, patients showed the same DLT.

RESULTS

Thirty-one patients (five pretreated in adjuvant setting) were enrolled in this study, and a total number of 293 cycles (median 6/patient) were administered. Dose escalation safely proceeded to 210/950/250 mg/m2 of CPT-11/5-FU/LFA. These dosages were considered as MTDs, since four of six patients showed grade 4 neutropenia, in one case associated with grade 3 stomatitis. A mild decrease of both the CPT-11 and 5-FU doses to 200 and 850 mg/m2, respectively, caused different DLTs (neutropenia and diarrhoea) in two out of seven patients. At these dosages, transient grades 3 or 4 neutropenia affected two patients each during their treatment, while only one patient suffered from a severe delayed diarrhoea. Other non-haematological toxicities were mild and manageable. Therefore, we recommend this latter dose level for further study. Major responses (3 complete and 11 partial) were reported in 14 patients, for an overall response rate of 45% (95% CI: 27%-64%) according to an intent-to-treat analysis. Responses were observed from first dose level, and in four of five previously treated patients. Median failure-free and overall survivals, after a median follow-up of 39 weeks, were 42 and 55 weeks, respectively.

CONCLUSIONS

The concurrent administration of CPT-11 and modulated 5-FU every two weeks is feasible at the recommended dosages. This regimen demonstrated interesting activity in the management of advanced colorectal cancer patients, and it probably better exploits the synergism between CPT-11 and 5-FU than recently tested alternating schedules. A phase II study is ongoing to more precisely define its activity and toxicity.

Direct translation of a protracted irinotecan schedule from a xenograft model to a phase I trial in children

PURPOSE

In a preclinical model of neuroblastoma, administration of irinotecan daily 5 days per week for 2 consecutive weeks ([qd x 5] x 2) resulted in greater antitumor activity than did a single 5-day course with the same total dose. We evaluated this protracted schedule in children.

PATIENTS AND METHODS

Twenty-three children with refractory solid tumors were enrolled onto a phase I study. Cohorts received irinotecan by 1-hour intravenous infusion at 20, 24, or 29 mg/m(2) (qd x 5) x 2 every 21 days.

RESULTS

The 23 children (median age, 14.1 years; median prior regimens, two) received 84 courses. Predominant diagnoses were neuroblastoma (n = 5), osteosarcoma (n = 5), and rhabdomyosarcoma (n = 4). The dose-limiting toxicity was grade 3/4 diarrhea and/or abdominal cramps in six of 12 patients treated at 24 mg/m(2), despite aggressive use of loperamide. The maximum-tolerated dose (MTD) on this schedule was 20 mg/m(2)/d. Five patients had partial responses and 16 had disease stabilization. On day 1, the median systemic exposure to SN-38 (the active metabolite of irinotecan) at the MTD was 106 ng-h/mL (range, 41 to 421 ng-h/mL).

CONCLUSION

This protracted schedule is well tolerated in children. The absence of significant myelosuppression and encouraging clinical responses suggest compellingly that irinotecan be further evaluated in children using the (qd x 5) x 2 schedule, beginning at a dose of 20 mg/m(2). These results imply that data obtained from xenograft models can be effectively integrated into the design of clinical trials.

New agents in gastrointestinal malignancies: Part 1: Irinotecan in clinical practice

In 1996 two chemotherapy agents were introduced by the U.S. Food and Drug Administration (FDA) with indications for the gastrointestinal malignancies for advanced colon and pancreatic cancers. The agents approved were irinotecan hydrochloride (CAMPTOSAR Injection, Pharmacia & Upjohn Company, Kalamazoo, MI; also investigated under the name CPT-11) for the second-line treatment of metastatic colorectal cancer, recurrent or relapsed, after 5-fluorouracil (5-FU)-based therapy, and gemcitabine hydrochloride (GEMZAR for injection, Eli Lilly and Company, Indianapolis, IN; also referred to as dFdC) for first-line treatment of locally advanced and metastatic cancer of the pancreas. Irinotecan and gemcitabine, with demonstrated activity in colorectal and pancreatic cancer, respectively, are generally well tolerated and can be administered safely on an outpatient basis. Clinically relevant activity is documented for both single agents. Therapy-related side effects are manageable with appropriate monitoring and intervention, and reversible with dose modification or discontinuation. This article is one of a two-part series on new chemotherapeutic agents for gastrointestinal malignancies. The first in the series, this article addresses the agent irinotecan hydrochloride (CAMPTOSAR Injection). The second article, appearing in a subsequent issue, will review gemcitabine hydrochloride (Gemzar for Injection). Both articles review the current clinical use, safety profile, and key patient management guidelines for these new and novel cytotoxics. As clinical and investigational use of irinotecan and gemcitabine increases, the oncology nurse and other members of the health care team will need to anticipate potential treatment associated toxicities and be knowledgeable in their early identification and management. As patient advocates, oncology nurses play a key role in treatment outcome and related quality of life through expert patient education, symptom recognition, and intervention individualized to patient tolerance. This first article of the series addresses irinotecan, which in 1996 was approved for the second-line therapy of metastatic colorectal cancer, recurrent or elapsed, after 5-fluorouracil (5-FU).

Characterisation of a synergistic interaction between a thymidylate synthase inhibitor, ZD1694, and a novel lipophilic topoisomerase I inhibitor karenitecin, BNP1100: mechanisms and clinical implications

We developed a combination protocol for inhibitors of thymidylate synthase (TS) and DNA topoisomerase I (Topo I) that can exert highly lethal effects in vitro against HCT-8 human colorectal cancer cells. The specific schedule was constructed so that a TS inhibitor could induce not only primary DNA damage but also cellular conditions optimal for the efficient action of a Topo I inhibitor. The initial drug treatment consisted of a brief exposure to a quinazoline-based antifolate, ZD1694. After an interval of approximately one cell-doubling time, cells were exposed for 8-24 h to BNP1100, a Karenitecin-class 7-thiomethyl-camptothecin, in the presence of 1-10 microM thymidine; the latter acted as a crucial factor to promote the collision of moving replication forks with the drug-stabilised DNA-Topo I cleavable complexes even under continuous TS inhibition. Clonogenic analyses confirmed that these mechanistically distinct drugs at clinically achievable concentrations worked in a highly synergistic manner, with a maximum effect abolishing the viability of virtually all cancer cells (> 99.9%). The pretreatment with ZD1694 increased the amount of DNA-bound Topo I by up to 4-fold and the DNA-damaging capability of BNP1100 by up to 15-fold. The possibility of at least four DNA-damaging pathways is proposed which might have resulted from the individual actions of TS and Topo I inhibitors as well as their concerted actions. Taken together, the present findings provided a logically permissible explanation as to why TS and Topo I inhibitors in concerted interactions induced a highly lethal effect which was more than a simple additive effect. Since these drugs are effective specifically on actively proliferating cancer cells, but not on non-cycling G0/G1 cells, this mechanism-based protocol may warrant consideration for clinical verification.

Phase I and pharmacokinetic study of irinotecan administered as a low-dose, continuous intravenous infusion over 14 days in patients with malignant solid tumors

PURPOSE

To evaluate the feasibility of administering irinotecan as a continuous intravenous infusion for 14 to 21 days.

PATIENTS AND METHODS

Patients with solid tumors refractory to standard therapy received continuous infusions of irinotecan by means of an ambulatory infusion pump. The starting dosage was 12.5 mg/m(2)/d for 14 days every 3 weeks. After identification of the maximum-tolerated dose for the 14-day infusion schedule, the protocol was amended to prolong the infusion duration to 17 and 21 days. Pharmacokinetics of irinotecan and SN-38 and its glucuronide were determined using high-performance liquid chromatography and noncompartmental modeling.

RESULTS

Thirty-three patients received 85+ courses. At the first dose level (12.5 mg/m(2)/d), cumulative grade 3 or 4 diarrhea and grade 3 or 4 neutropenia occurred in three of five patients. At a dosage of 10 mg/m(2)/d, 14-day administration resulted in grade 4 diarrhea in two of six patients and one episode of grade 4 vomiting occurred, whereas with 17-day administration, one episode of grade 3 nausea and two episodes of grade 3 or 4 diarrhea were observed in six patients. Increasing the number of days of infusion to 21 days was not feasible because of cumulative diarrhea. Hematologic toxicity was rare. The mean metabolic SN-38 area under the curve/irinotecan area under the curve ratio was 16% +/- 6% compared with 3% to 5% after short infusion schedules involving therapeutic dosages. Partial responses were observed in two patients with extraovarian and colorectal cancer.

CONCLUSION

The recommended dosage is 10 mg/m(2)/d for 14 days, repeated every 3 weeks. Enhanced metabolism of irinotecan to SN-38 may explain in part the low recommended dose for this schedule.

High-performance liquid chromatographic method for the simultaneous determination of the camptothecin derivative irinotecan hydrochloride, CPT-11, and its metabolites SN-38 and SN-38 glucuronide in rat plasma with a fully automated on-line solid-phase extraction system, PROSPEKT

We established a high-performance liquid chromatography (HPLC) method for the simultaneous determination of the camptothecin (CPT) derivative, irinotecan hydrochloride (CPT-11) and its metabolites, 7-ethyl-10-hydroxycamptothecin (SN-38) and SN-38 glucuronide (SN-38G) in rat plasma with a fully automated on-line solid-phase extraction system, PROSPEKT. Plasma samples were pretreated with 0.146 M H3PO4 to inactivate carboxylesterase and beta-glucuronidase in rat plasma, and added with the internal standard solution (0.146 M H3PO4 containing 1 microgram/ml CPT) and then analyzed. The method was validated for CPT-11 (5 to 25,000 ng/ml), SN-38 (5 to 2500 ng/ml) and SN-38G (2.5 to 500 ng/ml). This method enabled the determination of many samples within a relatively short time with easy sample preparation. It also had four advantages compared with conventional determination methods, i.e. automation of a complicated sample preparation, time-saving by the simultaneous determination of three compounds, the direct determination of SN-38G, and the small amount of plasma required for the determination.

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.

Combination of raltitrexed with other cytotoxic agents: rationale and preclinical observations

Agents for use in combination therapy should be effective as monotherapy in the tumour type of interest, have different mechanisms of action or pharmacology, and preferably non-overlapping toxicity profiles. Raltitrexed is effective as monotherapy in a number of tumour types, but it is hoped that combining it with other cytotoxic agents will lead to enhanced efficacy. Raltitrexed and 5-fluorouracil (5-FU) are specific and non-specific inhibitors, respectively, of thymidylate synthase, a critical enzyme in the de novo synthesis of DNA. Preclinical studies have indicated that raltitrexed and 5-FU have an incompletely overlapping spectrum of antitumour activity and may have additive or synergistic effects on colon carcinoma cells. These interactions are schedule-dependent (raltitrexed should precede 5-FU). Pre-treatment of colon carcinoma cells with raltitrexed has also been shown to increase intracellular levels of phosphoribosyl pyrophosphate resulting in increased incorporation of 5-FU nucleotides into RNA. Raltitrexed has a different mechanism of action from two other new agents active in colorectal cancer, irinotecan and oxaliplatin, and tumours are therefore not necessarily cross-resistant. Short pre-exposure of colon carcinoma cells to the irinotecan active metabolite, 7-ethyl-10-hydroxy-camptothecin (SN-38), prior to exposure to raltitrexed has consistently resulted in synergistic cell kill, whereas the reverse sequence is antagonistic. Preliminary results indicate that equitoxic doses of raltitrexed and cisplatin, or oxaliplatin, are antagonistic in two colon carcinoma cell lines. However, because there are major difficulties in translating preclinical drug combination results to the clinical settings, these results should be interpreted with caution.

Hyperthermic modulation of SN-38-induced topoisomerase I DNA cross-linking and SN-38 cytotoxicity through altered topoisomerase I activity

The effect of different temperatures (37-42.5 degrees C) on SN-38 (the active metabolite of CPT-11) cytotoxicity was examined in the human lung carcinoma cell lines H460 and Calu-6 as well as the murine fibrosarcoma cell line L929. The cytotoxicity of SN-38, determined by MTT cell survival assay, was significantly increased in each cell line in combination with 41.8 degrees C hyperthermia (x60-120 min); the combination of SN-38 with 40.5 degrees C and 42.5 degrees C, however, was unchanged compared to 37 degrees C. Determination of topoisomerase (Topo) I DNA cross-linking in Calu-6 cells and L929 cells after treatment with SN-38 showed the same temperature profile as seen in the cell-survival assays with increased Topo I DNA cross-linking after treatment with the combination of SN-38 and 41.8 degrees C hyperthermia and unchanged Topo I DNA cross-linking at 40.5 degrees C and 42.5 degrees C. To test the hypothesis that increased Topo I DNA cross-linking and SN-38 cytotoxicity at 41.8 degrees C is caused by hyperthermia-modulated changes in Topo I activity, catalytic activity of Topo I extracted from each cell line and of purified human Topo I was determined at 20-42.5 degrees C. Topo I activity was found to be gradually increased with rising temperatures, resulting in significantly higher activity at 41.8 degrees C compared to 37 degrees C; further increase of temperature past 41.8 degrees C decreased Topo I activity back to levels found at 37 degrees C. Our data are used to explain a series of events resulting in hyperthermic enhancement of Topo I DNA cross-linking and SN-38 cytotoxicity in combination with 41.8 degrees C hyperthermia via increased Topo I activity.

Irinotecan: a new antineoplastic agent for the management of colorectal cancer

OBJECTIVE

To review the pharmacologic, pharmacokinetic, therapeutic, and safety aspects of irinotecan, a new antineoplastic agent, and to assess its role in the treatment of colorectal and lung cancer.

DATA SOURCES

English-language articles from the MEDLINE database, January 1990-March 1998; Pharmacia & Upjohn Company; published articles and meeting abstracts.

STUDY SELECTION

Studies in humans with cancer, clinical case reports, and open clinical studies were reviewed. Efficacy studies were limited to trials with at least 20 evaluable patients.

DATA EXTRACTION

Relevant data were extracted from published reports and abstracts.

DATA SYNTHESIS

Irinotecan is an effective agent for the treatment of advanced colorectal cancer. It demonstrates significant activity as a first-line agent and in patients with disease that is refractory to fluorouracil-containing regimens. Activity against lung cancer has also been demonstrated. Limited data indicate activity against cancers of the ovary, cervix, stomach, and in non-Hodgkin's lymphomas. Major toxicity consists of myelosuppression and diarrhea.

CONCLUSIONS

Irinotecan is a useful addition to the antineoplastic drug family and offers significant efficacy for treatment of patients with fluorouracil-refractory colorectal cancer.

A phase II study of irinotecan alternated with five days bolus of 5-fluorouracil and leucovorin in first-line chemotherapy of metastatic colorectal cancer

PURPOSE

This multicenter phase II study was designed to assess the efficacy of the alternating schedule of irinotecan (CPT-11) with bolus 5-fluorouracil (5-FU) and leucovorin (LV) in first-line chemotherapy for metastatic colorectal cancer (CRC).

PATIENTS AND METHODS

Patients with histologically proven metastatic colorectal cancer, and at least one bidimensionally measurable lesion, aged 18-70, with performance status < or = 2, normal baseline biological values and no prior chemotherapy (or only adjuvant chemotherapy completed > or = 6 months before study entry) were selected. Treatment was irinotecan 350 mg/m2, i.v., day 1, alternating with leucovorin 20 mg/m2 i.v. and 5-FU 425 mg/m2, i.v. daily for five consecutive days, day 22-26 (Mayo Clinic regimen). One alternating cycle was to be performed every six weeks. Patients were evaluated for efficacy every alternating cycle. Treatment was administered until five alternating cycles, disease progression, unacceptable toxicity or patient refusal.

RESULTS

Thirty-three patients (28 chemotherapy-naïve and five with prior adjuvant treatment completed > 1 year prior to accrual) were enrolled. The objective response rate (RR) was 30% (95% CI: 16-49; 10 patients/33; nine partial response and one complete response). All responses were reviewed by an independent external review committee. An additional 49% of patients had stable disease. The median survival was 16 months, the one year survival amounted to 58% and the median progression free survival was 7.2 months. Relative dose intensity was nearly 90% for both drugs. Grade 3-4 diarrhea and neutropenia were the most frequent severe toxic events, seen in 24% and 64% of patients, respectively.

CONCLUSIONS

The alternating schedule of CPT-11 350 mg/m2 with five days bolus of 5-FU and low dose LV is an active and feasible regimen as front-line therapy for metastatic CRC. It is well tolerated, without evidence of overlapping toxicity. The response rate appears promising with regard to that expected with either single agent. This regimen warrants further assessment in randomized trials.

Bradycardia induced by irinotecan: a case report

Irinotecan chloride (CPT-11) is a new semi-synthetic camptothecin analogue which has encouraging antitumor activity against various malignancies. The major and unique toxicity of CPT-11 is diarrhea. Cardiovascular toxicity is rare and has not been found in clinical trials performed in Japan except for a very few cases of insignificant tachycardiac arrhythmia. We report a case of a 69-year-old man with recurrent colon cancer who suffered from bradycardia induced by infusion of CPT-11. Other toxicities including hematological toxicity and diarrhea were mild. Pharmacokinetic analysis using a limited sampling model revealed that the occurrence of bradycardia did not correlate with the excess of drug exposure. Although all of the cholinergic actions reported in the literature were mild, cardiotoxicity may come to be a clinically significant problem. If the events were examined more thoroughly, the cholinergic effect may be discovered more frequently. To administer CPT-11 safely needs meticulous monitoring not only for hematological toxicity and diarrhea but also for other cholinergic actions including bradycardia.

Clinical applications of the camptothecins

The camptothecin topoisomerase I-targeting agents are new class of antitumor drugs with demonstrated clinical activity in human malignancies, such as colorectal cancer and ovarian cancer. Currently, irinotecan and topotecan are the most widely used camptothecin analogs in clinical use and clinical trials are ongoing to better characterize their spectra of clinical activity, to determine their optimal schedules of administration and to define their use in combination with other chemotherapeutic agents. Newer camptothecin analogs in clinical development, such as 9-aminocamptothecin, 9-nitrocamptothecin, GI147211 and DX-8951f, are also being studied to determine if they have improved toxicity and efficacy profiles compared with existing analogs. Other potential clinical applications include the use of camptothecin derivatives as radiation sensitizers or as antiviral agents. The successful development of the camptothecins as antitumor agents highlights the importance of topoisomerase I as a target for cancer chemotherapy.

Clinical trials for advanced gastrointestinal cancers in Japan. Japan Clinical Oncology Group Gastrointestinal Oncology Study Group

No standard chemotherapy regimen for the treatment of advanced gastrointestinal cancer exists. However, 5-fluorouracil (5-FU) is being used more frequently as a key component of combination therapy regimens for this disease, and including cisplatin (CDDP) in combination therapy regimens produces significant tumor shrinkage. Although oral formulations of 5-FU are widely used in Japan, their clinical activity and toxicity have not been thoroughly evaluated. In 1992, the Japan Clinical Oncology Group initiated a phase III study in which the survival rates of patients treated with 5-FU 800 mg/m2/day for 5 days by continuous infusion (5-FUci), 5-FUci with CDDP 20 mg/ m2/day for 5 days by infusion, or oral uracil/Ftorafur 375 mg/m2/day with weekly MMC 5 mg/m2 i.v. were compared. This study was closed with 280 patients accrued in 1997, and final analysis was made in early 1998. Irinotecan and paclitaxel are new drugs with activity against gastric cancer. Combination chemotherapy consisting of irinotecan with CDDP has also been evaluated. For treatment of metastatic colorectal cancer, the only active drug previously available in Japan was 5-FU, although 5-FU + leucovorin is the international standard regimen. Irinotecan is now approved in Japan, Europe, and the USA and is the most effective drug for 5-FU-refractory patients. The optimal irinotecan and 5-FU combination regimen is being extensively examined but further trials aimed at accumulating basic data are warranted.

Camptothecins: a review of their development and schedules of administration

Used for centuries in traditional Chinese medicine, camptothecin was rediscovered in the 1950s during a search for compounds that could be used as a source for steroid synthesis. Due to its limited water solubility, a sodium salt was used in the early clinical trials. The severe toxicity and erratic absorption relegated this compound to the research laboratory until the 1980s when the topoisomerase enzyme was identified as the cellular target of camptothecin, the topoisomerase enzyme was found to be overexpressed in cancer cells and a structure-activity relationship was determined for camptothecin. These new developments brought the camptothecins back to the clinical setting for further testing. The various analogues that have been most studied to date include: irinotecan (CPT-11), and its derivative SN-38, topotecan, and 9-aminocamptothecin. Numerous trials have been conducted in an attempt to establish the efficacy in various tumour types, to determine the dose-limiting toxicity and to define the optimal schedule of administration. It seems that large doses of these drugs given on intermittent schedules are not effective. Our hypothesis is that the camptothecins require a prolonged schedule of administration given continuously at low doses or frequent intermittent dosing schedules to be most effective. With these schedules, normal haematopoietic cells and mucosal progenitor cells with low topoisomerase I levels may be spared, while efficacy is preserved.

New drugs in the treatment of colorectal carcinoma

BACKGROUND

Treatment with 5-fluorouracil (5-FU) plus leucovorin has been the unofficial standard therapy for patients with colorectal carcinoma (CRC) for more than a decade; however, the optimal dose and schedule remain a matter of debate. Recently several new drugs have shown activity in this disease. These include irinotecan (CPT-11); oxaliplatin; the thymidylate synthase inhibitors raltitrexed, uracil/tegafur (UFT), capecitabine, and S-1; the biochemical modulators trimetrexate and 5-ethynyluracil; and the monoclonal antibody 17-1A.

METHODS

The results of clinical trials with these and other new agents, as well as their current status and main characteristics, were reviewed.

RESULTS

Several of these agents, some with a novel mechanism of action, show promising activity in CRC. In combination with 5-FU and leucovorin, trimetrexate showed encouraging response rates in Phase II studies. Other interesting agents include capecitabine, UFT, and S-1. The biochemical modulator 5-ethynyluracil may allow the oral administration of 5-FU; however, results of Phase II clinical trials are not yet available. CPT-11 is in the most advanced stage of development and, based on consistent data generated in extensive Phase II studies, currently appears to be a reasonable choice for 5-FU-resistant or refractory disease. Another promising agent is oxaliplatin, which showed activity as first-line and second-line treatment.

CONCLUSIONS

Several new agents have shown promise in the treatment of CRC, and changes in the standard treatment of advanced or high risk CRC appear likely in the near future.

A phase II trial of combination of CPT-11 and cisplatin for advanced non-small-cell lung cancer. CPT-11 Lung Cancer Study Group

A phase I trial of the combination of irinotecan (CPT-11) with cisplatin in advanced non-small cell lung cancer (NSCLC) showed a very promising response rate of 54% in previously untreated NSCLC patients. This study was conducted to confirm the activity and toxicities of CPT-11 and cisplatin combination for previously untreated NSCLC in a multi-institutional phase II study. Seventy patients with stage IIIB or IV NSCLC received CPT-11 60 mg m(-2) intravenously (i.v.) on days 1, 8 and 15, and cisplatin 80 mg m(-2) (i.v.) on day 1 every 4 weeks. Assessments were made of response, survival and toxicities. Sixty-nine were eligible, and evaluable for toxicities and survival, and 64 patients evaluable for response. Thirty-three patients (52%; 95% confidence interval 39-64%) achieved an objective response, with one complete response (2%) and 32 partial responses (50%). The median duration of response was 19 weeks and the overall median survival time was 44 weeks. The 1-year survival rate was 33%. The major toxic effects were leucopenia and diarrhoea. Grade 3 or 4 leucopenia, neutropenia, and diarrhoea occurred in 32 patients (46%), 53 patients (80%), and 13 patients (19%) respectively. A combination of CPT-11 and cisplatin is very effective against non-small-cell lung cancer with acceptable toxicities.

Irinotecan (CPT-11) combined with cisplatin in patients with refractory or recurrent ovarian cancer

Irinotecan hydrochloride (CPT-11) is reportedly effective for the treatment of refractory or recurrent ovarian cancer. We investigated the antitumor efficacy and toxicity of combination therapy with CPT-11 and cisplatin in 25 patients (mean age 55 years, range 35-73 years) with refractory or recurrent ovarian cancer who had previously undergone platinum-based combination chemotherapy. Patients received two or more courses of treatment consisting of 50 or 60 mg/m2 of CPT-11 on days 1, 8 and 15 and 50 or 60 mg/m2 of cisplatin on day 1 administered intravenously. All patients were evaluable for the response and the toxicity profile. Complete responses were obtained in two (8.0%) patients and partial responses were obtained in eight (32.0%) patients, giving an overall response rate of 40% (10 of 25 patients) (95% CI 23.0-59.0%). The median duration of response was 5.5 months (range 2-27 months), the median time to tumor progression was 6 months (range 3-28 months) and the median overall survival was 12 months (range 3-39+ months). Grade 3 or 4 neutropenia, which was the most frequent and severe toxic effect, occurred in 36 (54.5%) of the 66 treatment courses and in 16 (64.0%) of 25 patients. The nadir of the leukocyte count occurred on days 18-19. Neutropenia was reversed by short-term administration of granulocyte colony-stimulating factor for 2-10 days. Less serious hematologic effects and non-hematologic effects, such as diarrhea, were also observed. This preliminary study showed that this regimen of CPT-11 and cisplatin was effective in patients with recurrent ovarian cancer.

A phase I clinical and pharmacologic study of a carboplatin and irinotecan regimen combined with recombinant human granulocyte-colony stimulating factor in the treatment of patients with advanced nonsmall cell lung carcinoma

BACKGROUND

This Phase I study was designed to determine the toxicity and efficacy of a carboplatin and irinotecan (CPT-11) regimen with recombinant human granulocyte colony-stimulating factor (rhG-CSF) support for patients with advanced nonsmall cell lung carcinoma.

METHODS

Treatment consisted of carboplatin administered intravenously (i.v.) on Day 1 plus CPT-11 i.v. on Days 1, 8, and 15. The carboplatin dose was calculated using Calvert's formula, where the target area under the plasma concentration versus the time curve (AUC) was 5 or 6 mg x min/mL. rhG-CSF (2 microg/kg) was administered daily, except on Days 1, 8, and 15, until the leukocyte count exceeded 20,000/mm3 (10,000/mm3 after Day 16). Cycles were repeated every 4 weeks. Groups entered the trial at escalating CPT-11 and carboplatin dose levels of 60 mg/m2 and 5 mg x min/mL, 70/5 and 60/6.

RESULTS

Twenty-one patients were enrolled in this study, of whom 20 were assessable for toxicity and therapeutic efficacy. Two of 6 patients experienced Grade 4 diarrhea at the 70/5 dose level, suggesting that this was the maximum tolerated dose (MTD). However, the 60/6 dose level was included because toxicities were very mild at the 60/5 dose level. At the 60/6 dose level, 1 of 6 patients experienced severe, life-threatening toxicity. Therefore, subsequent dose escalation was stopped and the study terminated. There were 7 responses (35%) among the 20 patients. At the 60/6 dose level (n=5), the observed carboplatin AUC after aiming for a target AUC of 6 was 5.9+/-0.9 mg x min/mL, as expected, although the AUCs of both CPT-11 and its active metabolite, SN-38, were lower than expected.

CONCLUSIONS

The recommended doses for Phase II studies are 60 mg/m2 of CPT-11 and a target AUC of 5 mg x min/mL for carboplatin, plus rhG-CSF. The combination of AUC-based carboplatin and CPT-11 with rhG-CSF support appears to be an active regimen in the treatment of patients with NSCLC.

Resistance to apoptosis induced by topoisomerase I inhibitors in multidrug-resistant HL60 leukemic cells

The induction of apoptosis by topoisomerase I inhibitors, camptothecin and SN38, was evaluated in drug-sensitive HL60 and multidrug-resistant (MDR) HL60-Vinc leukemic cells. MDR cells displayed a partial resistance to these apoptotic stimuli and this phenomenon was not modulated by verapamil. Basal free calcium concentrations were similar in both cell sublines and were not modified during treatment. Cytoplasmic pH was more acidic in sensitive cells than in MDR cells. Moreover, a significant acidification was obtained during the early stage of apoptosis in sensitive HL60 cells only. Basal Bcl-2 protein expression was found to be greater in MDR than in sensitive cells and was not modulated by apoptosis inducers. This increase of Bcl-2 in MDR cells could be due to the selection process as vincristine enhances Bcl-2 phosphorylation and expression in HL60 sensitive cells. MDR HL60-Vincristine cells therefore display a resistance to apoptosis induced by non-MDR drugs, possibly by Bcl-2 overexpression and inability of these drugs to mediate intracellular pH changes in these drug-resistant cells.