A phase II study of CPT-11, a new derivative of camptothecin, for previously untreated non-small-cell lung cancer

Current perspectives on camptothecins in cancer treatment

The camptothecins are a new class of chemotherapeutic agents which have a novel mechanism of action targeting the nuclear enzyme topoisomerase I. Knowledge of the structure-activity relationships of the parent compound camptothecin has led to the development of effective soluble analogues with manageable toxicities. Broad anti-tumour activity shown in preclinical studies has been confirmed in phase I/II studies for irinotecan and topotecan. Two other derivatives, 9-aminocamptothecin and GI 147211C, are undergoing phase I and early phase II evaluation. Although camptothecin is a plant extract, it and most of its derivatives are not affected by the classic P-gpMDR1 mechanism of resistance which may allow the development of novel combination chemotherapeutic regimens. Important areas of future endeavour will include the development of rational combination regimens and the pursuit of randomised trials. Based on single agent data, colorectal cancer and non-small-cell lung cancer should be the focus for future irinotecan studies. Small-cell lung cancer and ovarian carcinoma are logical tumour types to pursue with topotecan. Both 9-aminocamptothecin and GI 147211C are too early in their clinical evaluation to make recommendations about their future roles. Finally, the unfolding story of camptothecin analogue development will give important insights into the predictive value of preclinical observations on relative efficacy, schedule dependency, combination strategies and resistance mechanisms which have helped determine the strategies for clinical evaluation of these agents.

Promising new agents in the treatment of non-small cell lung cancer

A number of new drugs and drug classes have recently become available for clinical testing which demonstrate significant antitumor activity in non-small cell lung cancer. The preclinical rationale, mechanism of action, toxicity profile and results of early trials of paclitaxel, docetaxel, edatrexate, CPT-11, topotecan, vinorelbine and gemcitabine in non-small cell lung cancer are reviewed.

A phase III randomized trial of cisplatin plus vindesine versus cisplatin plus vindesine plus mitomycin C versus cisplatin plus vindesine plus ifosfamide for advanced non-small-cell lung cancer

A randomized trial of chemotherapy in 105 patients with advanced and metastatic non-small-cell lung cancer (NCSLC) was conducted in order to compare the effect of the additional drug mitomycin C (PVM) or ifosfamide (PVI), to the combination of cisplatin plus vindesine (PV). An objective response rate was observed in 42.8% of the patients treated with PVM, 42.4% with PVI and 28.6% with PV and these response rates were not statistically significant (P > 0.20). No patient achieved the complete response with either of the three regimens. Comparison of the median response durations among the three regimens showed an advantage of PVI over PVM (P < 0.02) and PV (P < 0.05). The median survival times (MST) were similar for all three regimens (PVM, 33.5; PVI, 40.0 and PV, 36.5 weeks); moreover, the difference in survival time between the three regimens of responders was not statistically significant. The univariate analysis showed that significant predictors of survival were performance status (PS) zero (P = 0.0002), limited disease (P = 0.004), no previous weight loss (P = 0.01) and normal serum albumin (P = 0.016), and in multivariate analysis by a stepwise Cox proportional hazard model, these were PS zero (a hazard ratio of 2.3, P = 0.0001) and limited disease (a hazard ratio of 1.9, P = 0.048). Toxicity did not differ among the three treatment regimens.

Water soluble inhibitors of topoisomerase I: quaternary salt derivatives of camptothecin

Eleven water soluble 7-substituted quaternary ammonium salt derivatives of 10,11-(methylenedioxy)- and 10,11-(ethylenedioxy)-(20S)-camptothecin were synthesized via the Friedlander reaction followed by nucleophilic displacement with an aromatic amine. All of these compounds were more potent than camptothecin in the in vitro cleavable complex assay. These inherently charged camptothecin derivatives were cytotoxic against three different human tumor cell lines (SKOV3, an ovarian adenocarcinoma; SKVLB a multidrug resistant ovarian adenocarcinoma; and HT-29, a colon carcinoma). A selected group of five compounds was evaluated in the nude mouse HT-29 xenograft model. Two of these quaternary salts (17 and 18) were more efficacious than Topotecan in delaying tumor growth. In an extended in vivo model, 18 demonstrated tumor regression.

Activity of gemcitabine in patients with non-small cell lung cancer: a multicentre, extended phase II study

Gemcitabine is a novel nucleoside analogue with activity in solid tumours. This study assessed the objective response rate to gemcitabine given weekly intravenously at a dose of 1250 mg/m2 for 3 weeks followed by 1 week of rest (one cycle) in chemonaive patients with inoperable non-small cell lung cancer (NSCLC). 161 patients with NSCLC were recruited from 10 sites in nine countries. Most patients had stage IIIb (31.3%) or IV (64.6%) disease, and 93.8% had a performance status of 0 or 1 according to the WHO scale. Of 151 evaluable patients, there were 3 complete responses and 30 partial responses lasting at least 4 weeks for an objective response rate of 21.8% (95% CI 15.5-29.3%). All responses were validated by an extramural Oncology Review Board. The mean duration of response was 8.8 months. The mean survival for all patients (16.1% of patients still alive 26 months after last patient started treatment) was 11.5 months. Improvements were also observed in secondary efficacy parameters such as performance status, weight, analgesic requirement, pain, and other disease-related symptoms including cough, dyspnoea, haemoptysis, anorexia, somnolence and hoarseness. Haematological and non-haematological toxicity was mild given the biological activity of gemcitabine. This study confirms gemcitabine as one of the most active agents in NSCLC with the added benefit of a modest toxicity profile and ease of administration on an out-patient basis. Gemcitabine is a suitable candidate for combination chemotherapy in patients with NSCLC.

Economic value of gemcitabine compared to cisplatin and etoposide in non-small cell lung cancer

Although chemotherapy costs have not been highlighted traditionally, there is increasing pressure to demonstrate the value of new treatments within the health care budget. Pharmaceutical companies are assessing the economic value of their products before launch. Gemcitabine is a nucleoside analogue developed for use in solid tumours. The purpose of this model was to investigate the clinical outcomes and potential cost savings for gemcitabine used as monotherapy compared to cisplatin and etoposide combination therapy in late stage non-small cell lung cancer (NSCLC), in a palliative (as opposed to aggressive) chemotherapy setting. Gemcitabine treatment data were taken from a large NSCLC study and data from retrospective chart reviews identified through the National Oncology Data Base. The model population and effectiveness of the two regimens were judged to be similar, except for baseline performance status. If drug costs were not included, the probability distribution resulting from the simulation showed median cost savings per cycle ranging from $US 1504 to $US 7425, with a medium value of $US 2154. The model suggested that gemcitabine would result in cost savings per cycle more than 90% of the time. Outpatient versus inpatient drug administrations accounted for the majority of potential cost savings. Most of the remaining cost savings were attributable to the difference in febrile neutropenia and antiemetic use. This economic model showed susbstantial savings if gemcitabine was used instead of cisplatin and etoposide combination therapy in the United States' community care setting. Some savings would be realized even if the location of treatment for both regimens was mostly outpatient. Assessment of the product's economic value before launch has assisted in our understanding of the potential areas of cost savings for gemcitabine and has guided us in the design of prospective randomized studies which included pharmacoeconomic endpoints.

Differential expression of DNA topoisomerases in non-small cell lung cancer and normal lung

DNA topoisomerases are ubiquitous nuclear enzymes, and important targets of cancer chemotherapy. Expression of topoisomerase genes is often correlated with in vitro chemosensitivity. We investigated the expression of the topoisomerase genes in normal lung and non-small cell lung cancer. Expression of topoisomerase II-alpha, topoisomerase II-beta, and topoisomerase I genes has been assessed in tumor samples of 60 patients who underwent operation for a non-small cell lung carcinoma, by RNase protection assay, and by immunohistochemistry. The expression of topoisomerase II-alpha gene was either undetectable or very low in normal lung, while most NSCLC expressed readily quantifiable levels of this gene. No alteration of the topoisomerase II-alpha gene was found by Southern blotting in the NSCLC samples. In contrast to topoisomerase II-alpha, topoisomerase II-beta was expressed in most normal as well as in tumor tissue samples, at a similar level. The levels of expression of both topoisomerase II isoforms was lower than that of human lung cancer cell lines. The results of the topoisomerase II mRNA expression were confirmed by immunohistochemistry. Whereas topoisomerase II-alpha staining was mainly limited to the nucleus, staining with topoisomerase II-beta antibody was exclusively observed in nucleoli. Topoisomerase I was localized in the nuclei and expression was mainly limited to tumor cells. By RNase protection, topoisomerase I expression in NSCLC samples was in the range of that of human lung cancer cell lines. The expression of the topoisomerase genes did not seem to be coordinated. In tumor cells, there was a positive association between expression of topoisomerase II-alpha and Ki-67, a marker of cell proliferation, as assessed by immunohistochemistry, but not with topoisomerase II-beta or topoisomerase I. Clinical characteristics of the patients, and their survival did not appear to be correlated to the level of expression of any of the topoisomerase genes, although a trend towards a shorter survival was observed in patients whose tumors expressed relatively high topoisomerase II-alpha mRNA levels.

IN CONCLUSION

(1) the two isoforms of topoisomerase II are differentially expressed in normal lung and NSCLC cells; (2) higher topoisomerase II-alpha expression is associated with higher cell proliferation in NSCLC; (3) the expression of topoisomerase II-alpha and topoisomerase I, but not of topoisomerase II-beta, was higher in tumor cells compared to normal lung. Given the differential expression of topoisomerases in normal lung and tumors, research of more potent and specific topoisomerase inhibitors might prove beneficial in non-small cell lung cancer. Immunohistochemistry may be indicated in prospectively investigating the correlation between expression of topoisomerases and results of chemotherapy treatment.

Topoisomerase I activity in squamous cell carcinoma of the head and neck

In recent preclinical and clinical trials, topoisomerase I inhibitors have shown great promise as antitumor agents. These agents are most effective against tumors with high topoisomerase I activity. Therefore, determining topoisomerase I activity in advance may predict response to topoisomerase I inhibitors. Squamous cell carcinoma of the head and neck and normal tissue samples were obtained from 12 patients. Cellular extracts were prepared, and topoisomerase I activity assays were performed. The results suggest that topoisomerase I activity in squamous cell carcinoma of the head and neck is increased approximately sixtyfold compared to normal tissue. Increased activity often correlates with clinical responsiveness; these results predict that topoisomerase I inhibitors should be effective and selective against squamous cell carcinoma of the head and neck.

Protective effects of kampo medicines and baicalin against intestinal toxicity of a new anticancer camptothecin derivative, irinotecan hydrochloride (CPT-11), in rats

In clinical use, irinotecan hydrochloride (CPT-11; 7-ethyl-10-[4-(piperidino)-1-piperidino]carbonyloxycamptothecin), a novel antitumor agent, causes a relatively high incidence of severe forms of diarrhea. We investigated whether baicalin, an inhibitor of beta-glucuronidase, which deconjugates the glucuronide of the active metabolite of CPT-11, SN-38 (7-ethyl-10-hydorxycamptothecin), and Japanese herbal medicines (Kampo medicines) which contain baicalin can ameliorate CPT-11-induced intestinal toxicity in rats. CPT-11 (60 mg/kg i.v. once daily for 4 consecutive days) induced intestinal toxicity characterized by diarrhea, loss of body weight, anorexia and disruption of intestinal epithelium. Treatment with baicalin (25 mg/kg p.o. twice daily) or Kampo medicines (TJ-14 and TJ-114; 1 g/kg p.o. twice daily) from the day before to 4 or 10 days after the start of CPT-11 administration resulted in significantly decreased weight loss, improved anorexia and delayed onset of diarrheal symptoms. Histological examination revealed that Kampo medicine-treated animals had less damage to the intestinal epithelium and that damage was repaired more rapidly than in control rats. These results suggest that the prophylactic use of Kampo medicines (TJ-14 and TJ-114) may be of value against CPT-11-induced intestinal toxicity.

Efficacy of topoisomerase I inhibitors, topotecan and irinotecan, administered at low dose levels in protracted schedules to mice bearing xenografts of human tumors

The efficacy of protracted schedules of therapy of the topoisomerase I inhibitors 9-dimethyl-aminomethyl-10-hydroxycamptothecin (topotecan) and 7-ethyl-10-[4-(1-piperidino)-1-piperidino]-carbonyloxycamptothecin (irinotecan; CPT-11) were evaluated against a panel of 21 human tumor xenografts derived from adult and pediatric malignancies. Tumors included eight colon adenocarcinomas, representing an intrinsically chemorefractory malignancy, six lines derived from childhood rhabdomyosarcoma (three embryonal, three alveolar) representing a chemoresponsive histiotype, sublines of rhabdomyosarcomas selected in vivo for resistance to vincristine and melphalan, and three pediatric brain tumors. All tumors were grown at the subcutaneous site. Topotecan was administered by oral gavage 5 days per week for 12 consecutive weeks. The maximum tolerated dose (MTD) was 1.5 mg/kg per dose. Irinotecan was given by i.v. administration daily for 5 days each week for 2 weeks [(d x 5)2](one cycle of therapy), repeated every 21 days. The MTD for three cycles was 10 mg/kg per dose. Treatment was started against advanced tumors. Topotecan caused a high frequency of objective regressions in one of eight colon tumor lines, whereas irinotecan caused complete regressions (CR) of all tumors in three colon lines and a high frequency of CRs in three additional lines. Both drugs demonstrated similar activity against rhabdomyosarcoma xenografts. Topotecan caused CR of all tumors in four of six lines, and irinotecan in five of six lines evaluated. Both agents retained full activity against tumors selected for primary resistance to vincristine, but only irinotecan retained activity against a tumor selected for primary resistance to melphalan. Both agents demonstrated good activity against brain tumor xenografts with irinotecan causing CR in two of three lines and topotecan inducing CR in one of three lines. Results indicate that low-dose protracted schedules of daily administration of these topoisomerase I inhibitors is either equi-effective or more efficacious than more intense shorter schedules of administration reported previously.

A new water-soluble camptothecin derivative, DX-8951f, exhibits potent antitumor activity against human tumors in vitro and in vivo

CPT-11, a semisynthetic derivative of camptothecin, exhibited strong antitumor activity against lymphoma, lung cancer, colorectal cancer, gastric cancer, ovarian cancer, and cervical cancer. CPT-11 is a pro-drug that is converted to an active metabolite, SN-38, in vivo by enzymes such as carboxylesterase. We synthesized a water-soluble and non-pro-drug analog of camptothecin, DX-8951f. It showed both high in vitro potency against a series of 32 malignant cell lines and significant topoisomerase I inhibition. The anti-proliferative activity of DX-8951f, as indicated by the mean GI50 value, was about 6 and 28 times greater than that of SN-38 or SK&F 10486-A (Topotecan), respectively. These three derivatives of camptothecin showed similar patterns of differential response among 32 cell lines, that is, their spectra of in vitro cytotoxicity were almost the same. The antitumor activity of three doses of DX-8951f administered i.v. at 4-day intervals against human gastric adenocarcinoma SC-6 xenografts was greater than that of CPT-11 or SK&F 10486-A. Moreover, it overcame P-glycoprotein-mediated multi-drug resistance. These data suggest that DX-8951f has a high antitumor activity and is a potential therapeutic agent.

Combined modality treatment for stage III non-small cell lung cancer

There are increasing reports of studies in which combined modality treatment is being tested in stage III non-small cell lung cancer. Randomized trials in which sequential chemoradiotherapy has been compared to radiation alone and in which single agent cisplatin and simultaneous thoracic radiation were compared to radiation are reviewed and discussed. The largest and the most mature phase II trials of preoperative chemotherapy are also included in this review. Similarly the results from recently reported small randomized trials evaluating preoperative treatment are described. Potential future directions for clinical trials are suggested, including the incorporation of new agents in combined modality regimens.

New chemotherapeutic agents for non-small cell lung cancer

The identification of new chemotherapeutic agents for the treatment of non-small cell lung cancer should proceed in a structured, logical fashion. Agents should be evaluated on the basis of multiple objective and subjective end points. A 15% or greater major objective response rate, demonstrated in multiple single-agent phase II trials, is considered the lower limit for an agent to be deemed clinically active in this disease. A number of drugs previously have been identified in this category, including cisplatin, ifosfamide, mitomycin, paclitaxel, and the vinca alkaloids vinblastine and vindesine. Most of these conventional agents have been explored alone, in a variety of doses and schedules, and in combination. In the last several years clinical development has produced new agents, including chloroquinoxaline sulfonamide, docetaxel, edatrexate, gemcitabine, irinotecan, topotecan, and vinorelbine, which hold promise for more successful treatment of this lethal disease.

New chemotherapy agents in the treatment of advanced non-small cell lung cancer: an update including data from the Seventh World Conference on Lung Cancer

Over the past two decades, modest gains have been made in chemotherapy for non-small cell lung cancer with the addition of cisplatin-based regimens to the therapeutic armamentarium. Over the last decade, several new agents with significant activity have reached the level of Phase II and III testing. This list of new drugs includes: navelbine, the taxanes--taxol and taxotere, gemcitabine, edatrexate and the camptothecins--irinotecan and topotecan. During this period, oral etoposide and epirubicin were re-investigated and biological agents such as the retinoids, interferons and interleukins were also explored as alternatives to traditional chemotherapy. As these new drug investigations proceeded, basic scientists made important discoveries which are now beginning to be applied to therapy. The future promises to combine these active new drugs with therapies directed against targets unique to non-small cell lung cancer cells.

New drugs in non-small cell lung cancer. An overview

Chemotherapy is rather ineffective in non-small cell lung cancer. However, in the last few years, a number of new anticancer agents have been developed which have definite activity in this disease. Among them are the taxanes and CPT-11, drugs with novel mechanisms of action, new antimetabolites (edatrexate and gemcitabine), and a new vinca alkaloid (vinorelbine). Furthermore, in the near future, the better understanding of lung cancer biology will help in devising new treatment strategies.

Relationship between the pharmacokinetics of irinotecan and diarrhea during combination chemotherapy with cisplatin

Two phase I trials of irinotecan (CPT-11) in combination with cisplatin were conducted. In both cases, the dose-limiting toxicities were leukopenia and/or diarrhea. During these trials the pharmacokinetics of CPT-11 and its active metabolite, 7-ethyl-10-hydroxycamptothecin (SN-38), were investigated to evaluate the relationship between pharmacokinetic parameters and diarrhea, since this is an unpredictable and severe toxicity of combination chemotherapy using CPT-11 and cisplatin. Twenty-three previously untreated patients with advanced lung cancer were evaluated in the pharmacokinetic study. Ten patients received CPT-11 at 80 or 90 mg/m2 plus cisplatin at 60 mg/m2. The other 13 patients received CPT-11 at 80 or 90 mg/m2 plus cisplatin at 80 mg/m2 with the granulocyte colony-stimulating factor support (2 micrograms/kg x 16 days). CPT-11 was given as a 90-min intravenous infusion on days 1, 8, and 15. Cisplatin was given on day 1. The pharmacokinetics of CPT-11 and SN-38 were analyzed on day 8 during the first course of treatment. The maximum tolerated dose of CPT-11 was 90 mg/m2 in both phase I trials. The severity of diarrhea was best correlated with the peak plasma concentration of SN-38 among the pharmacokinetic parameters tested. In addition, patients with a plasma SN-38 level > 12.4 ng/ml at 1.75 h after the start of CPT-11 infusion had a higher incidence of Eastern Cooperative Oncology Group grade 3-4 diarrhea than those with a lower SN-38 level (P = 0.0003). Stepwise logistic regression analysis identified the SN-38 concentration as a significant contributor to the development of diarrhea (P = 0.0021). We conclude that there is a clear relationship between the SN-38 concentration and diarrhea during chemotherapy with CPT-11 plus cisplatin.

Camptothecin analogues in the treatment of non-small cell lung cancer

Camptothecin is a natural product derived from the Oriental tree Camptotheca acuminata which has shown activity in a number of experimental tumors. Its clinical development was halted in the early-70s owing to its unpredictable and formidable toxicities. Two water-soluble camptothecin analogs have been synthesized recently and are currently in clinical trials: topotecan and CPT-11. Camptothecin and its derivatives are unique in that they represent the only family of topoisomerase I inhibitors. Topoisomerase I is a nuclear enzyme which modulates the topological structure of DNA by making transient single-stranded breaks. Pre-clinical studies have shown that CPT-11 and topotecan possess high and broad antitumor activity against a variety of experimental tumors including both non-small cell lung cancer (NSCLC) and small cell lung cancer. Lack of cross-resistance with most classical anticancer agents has been also demonstrated. Phase I studies have identified neutropenia to be the dose-limiting toxicity for topotecan while, for CPT-11, either neutropenia or diarrhoea were dose-limiting. Maximum Tolerated Doses (MTD) of both agents are greatly dependent upon the schedule used. A Phase II Japanese study of CPT-11 in advanced untreated NSCLC has been recently published. Given at the dose of 100 mg/m2 as a 90-min infusion, CPT-11 produced a 32% objective response rate out of 72 assessable untreated patients. Similar studies are in progress with topotecan. The same Japanese group has completed Phase I-II studies on the combination of CPT-11 with cisplatin. The optimal dose of CPT-11, which can be safely combined with cisplatin 80 mg/m2, was found to be 60 mg/m2.(ABSTRACT TRUNCATED AT 250 WORDS)

Phase II trial of CPT-11 in patients with advanced pancreatic cancer, an EORTC early clinical trials group study

BACKGROUND

CPT-11 (irinotecan) is a semi-synthetic derivative of camptothecin and exerts its activity by inhibiting DNA topoisomerase I. A phase II study of this drug was performed in patients with pancreatic cancer.

PATIENTS AND METHODS

Eligibility criteria included advanced non-chemotherapy-pretreated pancreatic cancer. CPT-11 was administered as a 30-minute i.v. infusion at a dose of 350 mg/m2 diluted in 250 ml normal saline every 3 weeks.

RESULTS

Thirty-four eligible patients were enrolled in the study, thirty-two of them were evaluated, and three achieved partial responses (9%; 95% C.I. = 3%-25%). The duration of response was 7.2, 7.5 and 7.8 months, respectively. Thirteen patients had no change, fourteen patients had progressive disease and two had early progressive disease. The median duration of survival for all patients treated was 5.2 months. The main toxicities (CTC grade > or = 3) were diarrhea, leukocytopenia, asthenia, nausea and vomiting in, respectively, 7%, 16%, 8%, 6%, 4% of the courses. These toxicities were reversible and manageable with anti-emetics and prophylactic or curative antidiarrheal agents.

CONCLUSION

CPT-11 is an interesting moderately effective drug in pancreatic cancer.

Limited sampling models for simultaneous estimation of the pharmacokinetics of irinotecan and its active metabolite SN-38

Irinotecan (CPT-11) is a novel topoisomerase I inhibitor with clinical activity in human malignancies. The objective of this study was to develop efficient limited sampling models (LSMs) to estimate simulataneously the area under the plasma concentration versus time curves (AUC) for both CPT-11 and its active metabolite SN-38. A total of 64 pharmacokinetic sets (> or = 24-h sampling) were obtained in phase I studies at doses ranging from 50 to 750 mg/m2 (0.5-h i.v. infusion). The patients were randomly assigned to a training data set (n = 32) and a test set (n = 32). Multiple linear regression analyses were used to determine the optimal LSMs based on the correlation coefficient (r), bias (MPE%, percentage of mean prediction error), and precision (RMSE%, percentage of root mean squared prediction error). Of these LSMs, the ones including maximal concentrations of CPT-11 (0.5 h, the end of the i.v. infusion) and metabolite SN-38 (approximately 1 h) were favored along with predictive precision and clinical constraints. Several bivariate models including a 6-h time point as the last sampling time (or 7 h) were found to be highly predictive of either the CPT-11 AUC or the SN-38 AUC. The chosen sampling time points were the ones that allowed the best compromise between the accurate determination of either compound alone with the same sampling times. The simultaneously best prediction of both CPT-11 and SN-38 AUCs was obtained with sampling time points harvested at 0.5, 1, and 6 h (or 7 h). With these sampling time points a trivariate model was selected for the determination of CPT-11 AUC namely, CPT-11 AUC (ng h ml-1) = 0.820 x C0.5h + 0.402 x C1h + 15.47 x C6h + 928, and a corresponding model was selected for the determination of metabolite AUC, i.e., SN-38 AUC (ng h ml-1) = 4.05 x C0.5h -0.81 x C1h + 23.01 x C6h - 69.78, where C(t) is the concentration in nanograms per milliliter of either compound at a given time t. These models performed well with the test data sets for CPT-11 AUC (r = 0.98, MPE% = -1.4, RMSE% = 13.9) and for SN-38 AUC (r = 0.95, MPE% = -6.5, RMSE% = 37.7). In addition to the determination of AUCs (and hence clearance), these models also allow the determination of the maximal concentrations of both compounds, which might be needed for pharmacodynamics studies.(ABSTRACT TRUNCATED AT 400 WORDS)

Phase II trial of topotecan in advanced or metastatic adenocarcinoma of the pancreas

PURPOSE

A phase II trial of topotecan, an inhibitor of topoisomerase I, was conducted in patients with advanced or metastatic adenocarcinoma of the pancreas to determine the activity and toxicity of topotecan.

PATIENTS AND MATERIALS

35 patients, previously untreated with chemotherapy, received topotecan 1.5 mg/m2/d for five days intravenously and repeated every 21 days. Patients were assessed for response after 3 cycles. Those with either clinical response or stable disease received additional cycles of the drug until toxicity developed or disease progression occurred.

RESULTS

Among 30 patients evaluable for response there were no complete responses and 3 partial responses (10%) for a total response rate of 10% (95% confidence interval = 0-20.6%). Stable disease for at least eight weeks was seen in 11 patients (36%). Median survival was 19 weeks (95% confidence interval 11 to 26 weeks). Therapy was generally well tolerated, with reversible granulocytopenia being the most common toxicity.

CONCLUSION

Topotecan given on a 5 day, short infusion schedule, demonstrated limited activity in pancreatic carcinoma with minimal toxicity. Further exploration of topotecan in pancreatic carcinoma using different dosing schedules is warranted.

A pharmacokinetic and pharmacodynamic analysis of CPT-11 and its active metabolite SN-38

In the present study, an attempt was made to determine the precise pharmacokinetics of 7-ethyl-10-[4-(1-piperidino)-1-piperidino]carbonyloxycamptothecin (CPT-11) and its active metabolite, 7-ethyl-10-hydroxycamptothecin (SN-38). The relationship between pharmacokinetic parameters and pharmacodynamic effects was also investigated to elucidate the cause of interpatient variation in side effects. Thirty-six patients entered the study. CPT-11, 100 mg/m2, was administered by IV infusion over 90 min weekly for four consecutive weeks. The major dose-limiting toxicities were leukopenia and diarrhea. There was a positive correlation between the area under the concentration-time curve (AUC) of CPT-11 and percent decrease of WBC (r = 0.559). On the other hand, episodes of diarrhea had a better correlation with the AUC of SN-38 (r = 0.606) than that of CPT-11 (r = 0.408). Multivariate analysis revealed that the AUC of SN-38, AUC of CPT-11 and indocyanine green retention test were significant variables for the incidence of diarrhea and that both performance status and AUC of CPT-11 were significant variables for percent decrease of WBC. The large interpatient variability of the degree of leukopenia and diarrhea is due to a great plasma pharmacokinetic variation in CPT-11 or SN-38. The AUCs of CPT-11 and SN-38 obtained from the first administration of CPT-11 correlate with toxicities, but it is impossible to predict severe side effects before the administration of CPT-11 at the present time.

New drugs in the treatment of non-small cell lung cancer

Non-small cell lung cancer accounts for 75% of all lung tumours, and only about 10% of patients will remain alive 5 years after diagnosis. Few cytotoxic drugs currently registered produce more than a 15% response rate as a single agent or 30%-35% in combination, with only modest survival benefits. New cytotoxic drugs entering phase II and III studies, however, appear to have more than 20% activity against this disease. They include the taxanes (taxol and taxotere), camptothecin analogues (CPT-11 and topotecan), antimetabolites (edatrexate and gemcitabine) and the vinca alkaloid, navelbine. Taxol produces response rates of about 25% in previously untreated patients and is currently undergoing trials at higher doses in combination with cisplatin and granulocyte colony-stimulating factor. Taxotere produces response rates of 33% in previously untreated patients and 21% in patients previously refractory to platinum-containing regimens. The camptothecin analogues, which are inhibitors of topoisomerase I, may produce response rates of up to 41% in previously untreated patients, but these results have varied considerably between different trials (response rates as low as 13.5% have been reported for topotecan). A phase II study with edatrexate produced a response rate of 32% but subsequent trials using combination chemotherapy including this agent have been disappointing. The activity of gemcitabine as a single agent is 20%-25%. Three ongoing phase II studies combining cisplatin and gemcitabine have shown response rates of up to 50%. Gemcitabine has minimal subjective toxicity. Navelbine produces response rates of 22%-33% as a single agent and up to 65% in combination. These new cytotoxic agents with significant activity in non-small cell lung cancer provide exciting potential for developing novel combination regimens in the advanced setting and as neoadjuvant and adjuvant therapy.

A limited sampling model for estimating pharmacokinetics of CPT-11 and its metabolite SN-38

The objective of this study was to develop a limited sampling model (LSM) to estimate the area under the curve (AUC) of 7-ethyl-10-[4-(1-piperidino)-1-piperidino]carbonyloxycamptothecin (CPT-11) and that of 7-ethyl-10-hydroxycamptothecin (SN-38) as predictive pharmacokinetic variables for leukopenia and episodes of diarrhea induced by CPT-11 administration. The model was developed with a training set consisting of pharmacokinetic studies in 36 patients who received a 90-min i.v. infusion of CPT-11 at a dose of 100 mg/m2. A multiple regression analysis of CPT-11 or SN-38 concentrations observed at each time point in the training set was used to predict the AUC of CPT-11 or SN-38. The final sampling models using only two time points were: AUCCPT-11 = 3.7891*C2.5 + 14.0479*C13.5 + 1.5463 AUCSN-38 = 0.5319*C2.5 + 19.1468*C13.5 + 72.7349 where C2.5 and C13.5 are the plasma concentration of CPT-11 (micrograms/ml) or SN-38 (ng/ml) at 2.5 and 13.5 h after the initiation of CPT-11 infusion, respectively. The models were validated prospectively on a separate test data set of 12 patients receiving the same dose of CPT-11 investigated in a previous study. Validation of the final LSM on the test data set gave values of root mean square error (RMSE) of 12.72% and 5.97% for the AUC of CPT-11 and that of SN-38, respectively. The model can be used to monitor the AUCs of both CPT-11 and SN-38 for the early prediction of toxicities and to establish a pharmacokinetically based dose modification strategy for safe administration of CPT-11.

Chemotherapy of stage IIIB and IV non-small-cell lung cancer

Currently, lung cancer is a leading cause of death in men with more than half million new cases diagnosed every year. Eighty percent of these tumors are non-small-cell carcinoma and 70% of these are unresectable or metastatic at the time of presentation, resulting in dramatically poor survival rates. The increasing number of drugs showing a significant activity against non-small-cell lung cancer and the widespread use of modern cisplatin based regimens offer some hope of progress and suggest that chemotherapy may have a role in treating this disease. A recent meta-analysis has confirmed the modest but significant survival benefit for patients treated with combined chemotherapy both in case of metastatic disease and in addition to radiotherapy, in locally advanced disease.

Synthesis of novel water-soluble 7-(aminoacylhydrazono)-formyl camptothecins with potent inhibition of DNA topoisomerase I

Eighteen new water-soluble 7-(aminoacylhydrazono)-formyl camptothecins were synthesized and evaluated for their ability to cause protein-linked DNA breaks and to inhibit topoisomerase I activity. Compared with camptothecin, five of the compounds were as potent or more potent in these tw assays but were less toxic in several cancer cell lines. The results suggest that the 7 position in the B ring is a suitable location for introducing a polar moiety into camptothecin producing analogues with enhanced topoisomerase I inhibiting activity.

Future directions in clinical research for lung cancer

Even since the Surgeon General's 1964 report, the mortality rate from lung cancer has continued to rise. Although there is evidence that this continued increase in mortality will slow or level in the next decade, lung cancer mortality is a major health problem destined to remain with us for at least the next generation. There have been no established advances in the early detection or prevention of lung cancer in the last 30 years and our therapies have increased the cure rate only from 5 to 13% in this 30-year interval. Biologic advances have outpaced clinical advances in recent times and many of the advances are now ripe for clinical exploitation. There are currently more exciting clinical trials for all phases of lung cancer than at any time and it will be stimulating to witness the results of the clinical trials discussed herein. Hopefully, the results of these studies will lead to a decrease in lung cancer mortality in the next century, much as it increased in the past century.

Treatment of adult T-cell leukaemia-lymphoma with irinotecan hydrochloride (CPT-11). CPT-11 Study Group on Hematological Malignancy

A late phase II study of a new camptothecin analogue, irinotecan hydrochloride (CPT-11), was conducted to evaluate the anti-tumour effect and toxicity in patients with refractory leukaemia and lymphoma including adult T-cell leukaemia (ATL)-lymphoma, in a multi-institutional cooperative study. All the patients with ATL had been previously treated with various conventional combination chemotherapies and were refractory to these therapies or had relapsed. CPT-11 was administered at a dose of 40 mg m-2 day-1 for three consecutive days repeated weekly until evidence of disease progression. One complete remission and four partial remissions were achieved in 13 assessable patients with ATL. The median total dose to achieve remission was 240 mg m-2 and the median duration of response was 31 days. The major toxicities were leucopenia (83%), diarrhoea (62%) and nausea/vomiting (69%). These were relatively severe, but they were generally tolerable and reversible. However, one patient died probably as a result of this therapy. No effective chemotherapy for adult T-cell leukaemia-lymphoma has yet been established, and the prognosis for patients with this disease is very poor. Our results suggest that CPT-11 may be a promising agent for this disease. Further combination therapy with CPT-11 is needed to improve the therapy for ATL.

CPT-11: population pharmacokinetic model and estimation of pharmacokinetics using the Bayesian method in patients with lung cancer

In this study, we aimed to develop a population pharmacokinetic model for CPT-11 and to use the Bayesian method to estimate CPT-11 pharmacokinetic parameters in each of 43 patients who received combined therapy consisting of CPT-11 and etoposide. The group was divided into first and second data sets of 30 and 13 patients, respectively. We developed a population pharmacokinetic model of CPT-11 based on the first data set. The individual pharmacokinetic parameters [area under the concentration curve (AUC) and clearance (CL)] were subsequently estimated by using the Bayesian method on the second data set. Plasma CPT-11 concentrations were measured by high-performance liquid chromatography, and compartmental pharmacokinetic models were fitted by the Bayesian method. The population pharmacokinetic model was developed by using the nonlinear mixed effect model. We selected the volume of the central compartment (Vc), CL, and distribution rate constants (K12, K21) as population pharmacokinetic parameters. The population mean values (CV%) of Vc, CL, K12, and K21 were, respectively, 31.8 (15.7%) liter/m2, 14.1 (27.8%) liter/h/m2, 1.1 (8.4%)/h, and 0.41 (30.3%)/h. Residual intraindividual variability was 22.9%. The optimal sampling regime for estimation of the AUC and CL in using the Bayesian method was the two time points of 1 and 8 h post infusion. The mean predictive error, the mean absolute predictive error, and the root mean squared error were -3.3, 9.4, 3.2% (AUC) and 6.3, 10.0, 3.5% (CL), respectively. We concluded that the AUC and CL of CPT-11 could be estimated from plasma concentrations at two times by using the Bayesian method.

Clinical studies of irinotecan alone and in combination with cisplatin

Irinotecan (CPT-11), a new derivative of camptothecin, showed schedule-dependent antitumor activity and toxicity in preclinical animal studies. We carried out a phase I study of weekly CPT-11 infusion, which indicated that the recommended dose for phase II studies was 100 mg/m2. In a phase II trial, CPT-11 achieved a response rate of 32% for non-small cell lung cancer (NSCLC). In two phase II trials, CPT-11 achieved objective response rates of 37% and 47% for small cell lung cancer (SCLC). The high activity of CPT-11 in these phase II studies suggested that the next rational step was to investigate combination chemotherapy. The first phase I trial of CPT-11 combined with cisplatin achieved an encouraging response rate of 54% in 27 patients with previously untreated NSCLC, and the recommended schedule for phase II studies was 60 mg/m2 of CPT-11 (days 1, 8, and 15) plus 80 mg/m2 of cisplatin (day 1) given at 4-week intervals. Given the high single-agent activity of CPT-11 against SCLC and NSCLC, a regimen with a higher dose of this agent and a lower dose of cisplatin seemed likely to be more effective. In the second trial, the cisplatin dose was accordingly reduced from 80 to 60 mg/m2, and the recommended dose of CPT-11 was concluded to be 80 mg/m2. Thus, reduction of the cisplatin dose to 60 mg/m2 allowed the safe administration of CPT-11 at 80 mg/m2 (33.3% dose intensification compared with the original regimen). The most recent trial of this combination with recombinant human granulocyte colony-stimulating factor (rhG-CSF) support demonstrated that the recommended dose is 80 mg/m2 of CPT-11 and 80 mg/m2 of cisplatin. Thus, we could raise the CPT-11 dose 33% above that given in the original regimen while maintaining the original cisplatin dose by the use of rhG-CSF support. Further trials are needed to evaluate the effect of CPT-11 given in combination with other active agents for the treatment of lung cancer.

Clinical, pharmacokinetic and biological studies of topotecan

The topoisomerase I inhibitor topotecan is a potent water-soluble camptothecin derivative with activity in a wide variety of preclinical models. Topotecan exhibits schedule dependency in vivo, with the greatest activity being observed on repeated dose schedules. On the basis of the initial clinical studies that showed a short plasma half-life, we attempted to prolong drug exposure by giving topotecan as a 24-h infusion weekly. In a phase I trial, we treated 32 patients at doses ranging from 1.0 to 2.0 mg/m2. The patient population had not been heavily pretreated with chemotherapy and was of good performance status. The incidence of neutropenia, which was dose-limiting, increased sharply with relatively small increments in dose. Doses greater than 1.5 mg/m2 were associated with nadirs that developed after one to three weekly treatments. A patient with metastatic colorectal cancer had a prolonged partial response. The plasma pharmacokinetics of topotecan (lactone and open forms) was characterized in 21 patients. Mean plasma steady-state drug levels were proportional to the dose and were within the range required to exert cytotoxicity in preclinical models. Plasma elimination curves were fit to a one-compartment model, in which the harmonic mean half-life of topotecan was 3.5 h. The ratio of the lactone to the total drug concentrations was constant throughout, which suggests that for this schedule the total drug concentration may be used as a measure of active lactone exposure. This conclusion is supported by the pharmacodynamic analysis, which revealed a positive correlation of both lactone and total drug steady-state concentrations with bone marrow toxicity. The further investigation of this and other infusional schedules in phase II trials will be conducted. The steady-state concentrations of total drug will be measured in several of these trials to establish its potential role in adaptive dosing using this schedule. Such a strategy is justified by the interpatient variability in toxicity and the steep dose-response curve observed in this study. Preliminary evidence of interpatient variability in the mRNA expression of topoisomerase I in the peripheral mononuclear cells and colon mucosa is presented. Trials are under way using biological endpoints for further selection of patients in whom the use of topoisomerase inhibitors may be therapeutically beneficial.

Efficacy of a new 5-fluorouracil derivative, BOF-A2, in advanced non-small cell lung cancer. A multi-center phase II study

Oral BOF-A2 (Emitefur), a new derivative of 5-fluorouracil (5-FU) containing both 1-ethoxymethyl-5-FU (EMFU), a masked form of 5-FU, and 3-cyano-2,6-dihydroxypyridine (CNDP), an inhibitor of 5-FU degradation, was administered to 71 non-small cell lung cancer (NSCLC) patients in a multi-center phase II study. The patients were scheduled to receive at least 2 courses of treatment, each consisting of 200 mg twice daily for 2 weeks followed by a 2-week rest period. Out of 62 evaluable patients, 11 (18%) responded (8 of 44 adeno- and 3 of 15 squamous cell carcinomas). Thirty-four patients showed no change and 17 progressive disease. The incidences of grade > or = 2 hematologic toxicity were 5-8% for leukopenia, thrombocytopenia, and anemia. The incidences of non-hematologic toxicity of grade > or = 2, such as anorexia, nausea/vomiting, and diarrhea, were close to 20% or lower.

7-Ethyl-10-[4-(1-piperidino)-1-piperidino] carbonyloxy camptothecin: mechanism of resistance and clinical trials

The camptothecin derivative 7-ethyl-10-[4-(1-piperidino)-1-piperidino]-carbonyloxy camptothecin (CPT-11) has attracted the attention of clinicians because of its high antitumor activity against refractory solid cancers. We established two CPT-11-resistant cell lines, a non-small-cell lung-cancer cell line (PC-7/CPT-11) from the parental PC-7 line and an ovarian cancer cell line (HAC-2/CPT-11) from the parental HAC-2 line. The mechanisms of resistance to CPT-11 in PC-7/CPT-11 cells were reduced conversion of CPT-11 to its active metabolite SN-38 and point mutation topoisomerase I. Those in HAC-2/CPT-11 cells were reduction of topoisomerase I activity and decreased sensitivity of topoisomerase to topoisomerase I inhibitors. No point mutation of the topoisomerase was observed in HAC-2/CPT-11 cells. We conducted two phase I trials using CPT-11 in combination with other anticancer agents. One was a phase I trial of CPT-11 and cisplatin given with a fixed dose of vindesine to patients with advanced non-small-cell lung-cancer and the other was a phase I study on a topoisomerase-targeting combination of CPT-11 and etoposide (VP-16) in patients with various malignant solid tumors. The results of the first trial indicated that the recommended dose of CPT-11 for phase II studies was 80 mg/m2 combined with 3 mg/m2 vindesine on days 1 and 8 and 60 mg/m2 cisplatin on day 1. In the second trial, the recommended dose of CPT-11/VP-16 given with recombinant granulocyte colony-stimulating factor (on days 4-17) was found to be 60/60 mg/m2. In both trials, diarrhea and granulocytopenia were considered to be dose-limiting toxicities.

Treatment of non-small cell lung cancer: new cytostatic agents

The literature on new cytostatic drugs in the treatment of non-small cell lung cancer and on new methods for administration of established drugs has been reviewed back to 1985. Two well-known cytostatic drugs, ifosfamide and etoposide, have been evaluated in trials using oral administration instead of the usual intravenous route, and a total of 26 new investigative drugs has also been evaluated. Oral administration of etoposide is associated with an accumulated response rate of 17% in four studies using a dose of 50 mg/m2 daily for 2-3 weeks, followed by 1 week's rest. Oral administration of ifosfamide yields an accumulated response rate of 18% when the dose intensity is 7 g or more during a 4-week period. Among the new drugs tested, the most promising seem to be campthothecin-11, gemcitabine, vinorelbine, taxol, fotemustine, and zeniplatin which have all shown response rates above 20% among previously untreated patients. Also, the antimetabolites 10-EDAM and trimetrexate and the platinum analogues carboplatin and (glycolate-0,0) diammine-platinum(II) are of interest, with cumulative response rates above 15% in previously untreated patients.