Phase II trial of topotecan as a 21-day continuous infusion in patients with advanced or metastatic adenocarcinoma of the pancreas

Evaluation of Phase II Trial Design in Advanced Pancreatic Cancer

OBJECTIVES

We evaluated how well phase II trials in locally advanced and metastatic pancreatic cancer (LAMPC) meet current recommendations for trial design.

METHODS

We conducted a systematic review of phase II first-line treatment trial for LAMPC. We assessed baseline characteristics, type of comparison, and primary end point to examine adherence to the National Cancer Institute recommendations for trial design.

RESULTS

We identified 148 studies (180 treatment arms, 7505 participants). Forty-seven (32%) studies adhered to none of the 5 evaluated National Cancer Institute recommendations, 62 (42%) followed 1, 31 (21%) followed 2, and 8 (5%) followed 3 recommendations. Studies varied with respect to the proportion of patients with good performance status (range, 0%-80%) and locally advanced disease (range, 14%-100%). Eighty-two (55%) studies concluded that investigational agents should progress to phase III testing; of these, 24 (16%) had documented phase III trials. Three (8%) phase III trials demonstrated clinically meaningful improvements for investigational agents. One of 38 phase II trials that investigated biological investigational agents was enriched for a biomarker.

CONCLUSIONS

Phase II trials do not conform well to current recommendations for trial design in LAMPC.

Systemic Chemotherapy in Advanced Pancreatic Cancer

Pancreatic cancer remains one of the most lethal cancers. These patients often have multiple symptoms, and integrated supportive care is critical in helping them remain well for as long as possible. Fluorouracil-based chemotherapy is known to improve overall survival (OS) by approximately 3 months, compared to the best supportive care alone. A 1997 study comparing gemcitabine and fluorouracil treatment of advanced pancreatic cancer patients showed an improvement in OS of 1 month in patients receiving gemcitabine. Over the next 10 years, multiple randomized studies compared single-agent gemcitabine with combination chemotherapy and showed no effective survival improvement. However, the addition of erlotinib, an epidermal growth factor receptor (EGFR) inhibitor, was associated with a significant improvement in OS of approximately 2 weeks. However, adoption of this regimen has not been widespread because of its limited effect and added toxicity. Two clinical trials have recently prolonged OS in advanced pancreatic cancer patients by almost 1 year. The first compared FOLFIRINOX with gemcitabine alone, and was associated with a significant improvement in median survival. The second compared gemcitabine and nab-paclitaxel with gemcitabine alone, and was associated with improvements in OS. At present, these regimens are considered standard treatment for patients with good performance statuses.

Comparison of DC Bead-irinotecan and DC Bead-topotecan drug eluting beads for use in locoregional drug delivery to treat pancreatic cancer

DC Bead is a drug delivery embolisation system that can be loaded with doxorubicin or irinotecan for the treatment of a variety of liver cancers. In this study we demonstrate that the topoisomerase I inhibitor topotecan hydrochloride can be successfully loaded into the DC Bead sulfonate-modified polyvinyl alcohol hydrogel matrix, resulting in a sustained-release drug eluting bead (DEBTOP) useful for therapeutic purposes. The in vitro drug loading capacity, elution characteristics and the effects on mechanical properties of the beads are described with reference to our previous work with irinotecan hydrochloride (DEBIRI). Results showed that drug loading was faster when the solution was agitated compared to static loading and a maximum loading of ca. 40-45 mg topotecan in 1 ml hydrated beads was achievable. Loading the drug into the beads altered the size, compressibility moduli and colour of the bead. Elution was shown to be reliant on the presence of ions to perform the necessary exchange with the electrostatically bound topotecan molecules. Topotecan was shown by MTS assay to have an IC(50) for human pancreatic adenocarcinoma cells (PSN-1) of 0.22 and 0.27 microM compared to 28.1 and 19.2 microM for irinotecan at 48 and 72 h, respectively. The cytotoxic efficacy of DEBTOP on PSN-1 was compared to DEBIRI. DEPTOP loaded at 6 & 30 mg ml(-1), like its free drug form, was shown to be more potent than DEBIRI of comparable doses at 24, 48 & 72 h using a slightly modified MTS assay. Using a PSN-1 mouse xenograft model, DEBIRI doses of 3.3-6.6 mg were shown to be well-tolerated (even with repeat administration) and effective in reducing the tumour size. DEBTOP however, was lethal after 6 days at doses of 0.83-1.2 mg but demonstrated reasonable efficacy and tolerability (again with repeat injection possible) at 0.2-0.4 mg doses. Care must therefore be taken when selecting the dose of topotecan to be loaded into DC Bead given its greater potency and potential toxicity.

Systemic therapy for metastatic pancreatic adenocarcinoma

Systemic treatment of metastatic pancreatic adenocarcinoma achieves only modest benefits, with evidence indicating a survival advantage with 5-fluorouracil (5-FU) over best supportive care alone, and further advantage of single-agent gemcitabine over 5-FU. There are very few regimens better than single-agent gemcitabine despite multiple trials of cytotoxic and targeted agents. The addition of a platinum agent has improved response rate but not survival. The addition of erlotinib has improved survival but only by a small margin. The use of gemcitabine in multidrug regimens containing one or more of: a platinum agent; fluoropyrimidine; anthracycline; and taxane has demonstrated advantages in response rate, progression-free survival and, in one randomized study, overall survival. After gemcitabine failure, second-line therapy with oxaliplatin and 5-FU provides a further survival advantage. Further advances depend upon the current and future clinical trials investigating enhanced delivery of current agents, new agents and novel modalities, improved supportive care, and treatment more tailored to the individual patient and tumour.

Dose-Finding Phase I Clinical and Pharmacokinetic Study of Orally Administered Irinotecan in Patients with Advanced Solid Tumors

PURPOSE

The aim of this study was to determine the daily maximum tolerated dose (MTD) and the dose-limiting toxicity for the following administration schedules: oral irinotecan given over 14 days every 3 weeks (part I) and oral irinotecan administered concomitantly with capecitabine over 14 days every 3 weeks (part II). In total, 42 patients (17 male and 25 female) with solid tumors refractory to standard therapy entered the study.

EXPERIMENTAL DESIGN

Treatment in part I consisted of irinotecan administered orally as semisolid matrix capsules at doses of 25, 30, and 35 mg/m(2) once daily to confirm the MTD of our earlier study. In part II treatment, dose levels for irinotecan combined with capecitabine were 20/1,600, 25/1,600, 30/1,600, and 30/2,000 mg/m(2)/d.

RESULTS

The median number of cycles administered per patient was 2.0 (range, 1-12) in part I and 2.0 (range, 1-13) in study part II. Gastrointestinal toxicities (grade 3 nausea, grades 3 and 4 vomiting, and grades 3 and 4 diarrhea) were dose limiting in both parts of the study. There were no grade 3 or 4 hematologic toxicities. The MTD was 30 mg/m(2)/d for irinotecan single agent and 30/1,600 mg/m(2)/d for the combination with capecitabine. Absorption of irinotecan was rapid, and peak concentrations of irinotecan and metabolite SN-38 were reached within 0 to 3 and 1.5 to 4.0 hours, respectively.

CONCLUSIONS

In conclusion, oral irinotecan and capecitabine is feasible and well tolerated, and the recommended dose for phase II studies is 30/1,600 mg/m(2)/d administered daily for 14 days every 3 weeks.

Topoisomerase I Inhibitors in the Treatment of Gastrointestinal Cancer: From Intravenous to Oral Administration

This article reviews the current status of the topoisomerase I (top I) inhibitors in the treatment of gastrointestinal (GI) malignancies. We focus on oral drug administration, the mode of administration that is generally preferred by patients with cancer. However, the great majority of the studies have been performed with intravenous (I.V.) administration. The most extensively investigated GI malignancy in phase I/II studies is colorectal cancer (CRC), for which I.V. irinotecan is currently approved in the United States and Europe. We discuss the activity and efficacy of irinotecan as a single agent in CRC and in combination regimens. Also, results obtained with monotherapy and in combination treatment in other GI malignancies such as esophageal, gastric, and pancreatic cancer are discussed. Few phase I studies have been performed with oral irinotecan and its clinical activity has not yet been fully determined. Several top I inhibitors are discussed, including topotecan, 9-aminocamptothecin, rubitecan, exatecan, and lurtotecan. None of these agents, given orally or intravenously, have shown activity in CRC similar to that of I.V. irinotecan. However, several agents show promising results in other GI malignancies, eg, rubitecan and exatecan in pancreatic cancer. A complicating factor in the oral administration of the top I inhibitors is the often encountered low and variable oral bioavailability. This can partly be explained by the high affinity for the drug efflux pumps BCRP (ABCG2) and P-glycoprotein, which are highly expressed in the epithelial apical membrane of the GI tract. A novel approach to improve the oral bioavailability of the top I inhibitors by temporary blockade of the drug transporter BCRP is described.

Review article: chemotherapy for pancreatic cancer

Pancreatic cancer is a common, highly lethal disease that is rising in incidence. Chemotherapy based on 5-fluorouracil (5-FU) has been shown to prolong survival in advanced pancreatic cancer. Gemcitabine improves major symptoms and survival outcomes compared with bolus 5-FU. Many novel small molecules are being widely and actively researched. These compounds are based on classical mechanisms of action as well as biological therapies targeting novel cellular survival pathways, and include fluoropyrimidines, nucleoside cytidine analogues, platinum analogues, topoisomerase-inhibitors, antimicrotubule agents, proteasome inhibitors, vitamin D analogues, arachidonic acid pathway inhibitors, histone deacytylator inhibitors, farnesyltransferase inhibitors and epidermal growth factor receptor therapies. Adjuvant chemotherapy has also demonstrated the best survival outcomes following resection compared to other adjuvant or neo-adjuvant strategies such as radiation-based treatments. These benefits are superimposed on the dramatic increase in resectability rates and reduction in post-operative mortality achieved by centralisation of treatment in high-volume speciality centres. Newer 'small-molecule' drugs as well as the latest 'large-molecule' biological agents hold considerable promise for the future. Real advances are anticipated over the next five years but are dependent on large randomised controlled trials for success.

OSI-211, a novel liposomal topoisomerase I inhibitor, is active in SCID mouse models of human AML and ALL

OSI-211 (liposomal lurtotecan), was evaluated using several different dose schedules (1mg/kg, d1-5, 1.75 mg/kg d1, 3, 5 and 6 mg/kg d1, 8) in severe combined immunodeficient (SCID) mouse models of acute myelogenous leukemia (AML) and acute lymphocytic leukemia (ALL) with early treatment (ET, days 6-8) or late treatment (LT, days 15-19), examining early and advanced disease, respectively. Due to the aggressive nature of the Molt-4 model, the ET and LT were accelerated to day 3 or 4 and day 8 post-implant, respectively. For each model, 2 x 10(7) (KBM-3B) or 1 x 10(7) (Molt-4, HL-60 and CEM) leukemia cells were injected intravenously into the tail vein. Each control and test group consisted of eight animals. All three schedules (1mg/kg qd1-5, 1.75 mg/kg d1, 3, 5 and 6 mg/kg d1, 8) increased the life span of OSI-211 treated animals in each model, with a tendency toward improved efficacy with the 6 mg/kg d1, 8 schedule. As a result, the activity of the 6 mg/kg d1, 8 schedule is detailed for each model. ET significantly (P<0.005) increased survival in the KBM-3B model with 86% long-term survivors (LTS). Using PRC analysis, human beta-globin gene sequences in one or several tissues were amplified in all but 3 LTS, suggesting minimal residual disease in 26 of the 29 LTS. LT also significantly (P<0.005) improved average life span in the KBM-3B model, with an average ILS=196+/-11% and one LTS. Treatment of HL-60 leukemia animals significantly (P<0.005) increased life span, with an ILS=213+/-9% and two LTS for ET, and with an ILS=219+/-4% and no LTS for LT. Treatment of Molt-4 animals, the most aggressive leukemia model tested, significantly (P<0.005) increased life span, with an average ILS=181+/-3% and no LTS for ET and an average ILS=172+/-1% with no LTS for LT. In the CEM model, ET resulted in a significantly (P<0.005) improved ILS=244+/-24% with one LTS. In comparison to OSI-211, treatment with DaunoXome, the liposomal formulation of daunorubicin, a drug with clinical efficacy in AML and ALL, had no effect on survival in the KBM-3B, nor Molt-4 A4 leukemia models when administered at its maximum or near maximum tolerated doses of 3mg/kg d1, 8. These data demonstrate that OSI-211 has potent antileukemia activity in preclinical SCID mouse AML and ALL leukemia models, supporting the clinical investigation of OSI-211 for hematological malignancies.

Chemotherapeutic advances in pancreatic cancer

Advances in chemotherapy for pancreatic cancer have been limited. In the past decade, the standard therapy for metastatic disease has switched from 5-fluorouracil (5-FU) to gemcitabine. However, several other cytotoxic agents have shown limited but promising efficacy in pancreatic cancer, and many of these appear to be well suited for combination chemotherapy. Although 5-FU and cisplatin have not demonstrated substantial survival benefits when combined with gemcitabine, results of several phase III trials with other agents are still pending. For locally advanced disease, most recent studies have incorporated gemcitabine into combined-modality therapy. Similarly, in surgically resectable disease, current trials are incorporating gemcitabine into adjuvant therapy. Other trials are using neoadjuvant therapy as a possible means to improve upon current surgical results. However, much hope comes from the development of newer "targeted" therapies for this disease. Although matrix metalloproteinase inhibitors and farnesyl transferase inhibitors did not appear to be effective in initial studies, other targeted therapies are beginning to enter clinical trials.

Phase I study of sequential administration of topotecan and 5-fluorouracil in patients with advanced malignancies

Topotecan is a topoisomerase-I inhibitor, a drug that stabilizes a covalent complex of enzymes and causes strand cleavage of DNA. 5-Fluorouracil (5FU) is an antimetabolite that interferes with DNA synthesis. Preclinical studies using human cancer cell line models have shown potential therapeutic synergy between these two drugs by showing the maximum cytolytic effect using sequential 5FU followed by topotecan. In the current study, 5FU was used at a fixed dose of 375 mg/m2 given intravenously for five consecutive days on a 28 day cycle. Topotecan was dose-escalated in cohorts of patients from 0.5 to 1.0 mg/m2 given intravenously for 5 days after the 5FU dose. Eleven patients were entered at different dose levels. Both hematological and gastrointestinal toxicity were dose limiting. Diarrhea was the dose-limiting toxicity at the dose of 0.75 mg/m2 of topotecan. Two cases of grade 4 neutropenia were also observed at this dose level. One patient with small cell lung cancer had a complete response, while one patient with metastatic colorectal cancer had a partial remission. Three other patients had stable disease, lasting between 6 and 8 months. Overall, the regimen was well tolerated. A phase II study using a dose of 5FU at 375 mg/m2 followed by topotecan at 0.75 mg/m2 intravenously over 5 days every 28 days is recommended.

A phase I trial of topotecan and gemcitabine administered weekly for 3 consecutive weeks to patients with advanced tumors

BACKGROUND

The complementary action of gemcitabine and topotecan on DNA metabolism suggested the potential for their use in combination chemotherapy. Gemcitabine, a synthetic cytidine analogue chain terminator, and topotecan, a topoisomerase-1 inhibitor, have been reported to have broad antitumor activity and are approved for clinical use.

METHODS

The cytotoxicity of the combination in various models in vitro was additive. In the current study, the authors conducted a Phase I study to determine the recommended Phase II doses and toxicity profile of gemcitabine and topotecan when administered weekly in combination. Gemcitabine (400--1000 mg/m(2)) was given intravenously over 30 minutes followed by a 15-minute infusion of topotecan (0.75--2.5 mg/m(2)) weekly for 3 consecutive weeks in a 4-week treatment cycle. Thirty-eight patients with advanced refractory solid tumors and good performance status were treated.

RESULTS

Myelosuppression in the form of granulocytopenia and thrombocytopenia were the major dose-limiting toxicities. Other toxic effects included anemia, nausea, and elevated hepatic transaminases. Partial responses were observed in two patients (one with nonsmall cell lung carcinoma and one with pancreatic carcinoma). Disease stabilization occurred in five patients (three with pancreatic carcinoma, one with rectal carcinoma, and one with metastatic carcinoma of an unknown primary site). Gemcitabine, 1000 mg/m(2), and topotecan, 2.5 mg/m(2), were the maximum tolerated doses for this combination.

CONCLUSIONS

The results of the current study showed that the combination of weekly gemcitabine and topotecan for 3 weeks in a 4-week cycle schedule appeared to be well tolerated and was associated with clinical activity. Therefore, this combination is recommended for a further Phase II evaluation.

Current status of and future prospects for the medical management of adenocarcinoma of the exocrine pancreas

Adenocarcinoma of the exocrine pancreas is one of the most refractory neoplasms to medical treatment. Although of marginal value, 5-fluorouracil (5-FU) alone or in combination with other agents or modalities has been the standard surgical adjuvant approach to localized unresectable tumor as well as the standard treatment for disseminated pancreatic cancer. Recently, a new chemotherapeutic agent, gemcitabine, has been shown to be somewhat more effective than 5-FU against metastatic pancreatic cancer. Treatment with gemcitabine usually results in a greater likelihood of objective response and better symptom control than treatment with 5-FU or drug combinations that include 5-FU. However, treatment with gemcitabine does not improve overall survival of patients with disseminated neoplasm. Newer promising agents such as 9-nitrocamptothecin have recently entered clinical trials, and novel modalities (e.g., gene therapy) are nearing full-scale clinical trial. There are reasons to believe that these and other new initiatives may soon significantly improve the medical management of adenocarcinoma of the exocrine pancreas.

Oral topoisomerase 1 inhibitors in adult patients: present and future

The renewed interest in topoisomerase 1 inhibitors, based on new insights on the mechanism of action and the development of semi-synthetic derivates of camptothecin with a more favourable toxicity profile, has led to extensive preclinical and clinical research. Significant levels of anti-tumor activity in human tumor xenografts were seen especially with prolonged duration of exposure. Since oral drug delivery is a more convenient method for prolonged drug administration, and preferred by patients, further development of oral formulations seems attractive. Common concerns in the development of oral formulations are their sometimes low oral bioavailability and the frequently large intra- and interpatient variation in systemic exposure. Efforts to improve absorption and minimize intestinal metabolism/efflux of the oral chemotherapeutic agent using new formulas might lead to better bioavailability. Pharmacokinetic and pharmacodynamic evaluations have enabled guidance in recommendations of schedules. Given the interpatient variation in exposure it is interesting to note that flat dosing of topotecan resulted in the same systemic exposure compared with the more complex dosing per body surface area. In order to diminish the interpatient variation in exposure to 9-AC a limited sampling model for oral 9-AC was developed, enabling prediction of the systemic exposure for 9-AC and optimizing treatment for any given patient. Drug sequencing plays a key role in the combination topotecan/cisplatin and might be important for combination with other classes of drugs. Therefore, forthcoming phase 1 trials on combination therapy with oral topoisomerase 1 inhibitors should include studies on sequence dependence and pharmacokinetic analyses to evaluate any mutual interaction.

Experimental drugs and drug combinations in pancreatic cancer

The current role of chemotherapy in pancreatic cancer is limited. Chemotherapy usually consists of 5-fluorouracil (5FU) and gemcitabine either as a single agent or in combinations. However, response rates are below 15% with minor effects on overall survival. Due to the aggressive behavior of the disease, current emphasis of new experimental chemotherapy is also focusing on clinical benefit: improvement of pain, performance status or weight. The results with gemcitabine indicated that evaluation of new chemotherapeutic agents in pancreatic cancer should not be limited to the evaluation of response rates; single agent gemcitabine not only showed higher response rates than 5FU, but also resulted in clinical benefit for the patients. Several new agents have been introduced into the clinic for treatment of various gastro-intestinal malignancies, whereas novel agents with different types of targets, such as marimastat deserve further attention. Several oral formulations of 5FU, such as capecitabine, UFT, and eniluracil with 5FU, aim to simulate long-term continuous infusion. Response rates of these formulations are comparable to those of 5FU continuous infusion and 5FU bolus injections. However, the convenience of oral administration with reliable plasma drug concentrations makes these agents very attractive as a replacement of traditional 5FU administration. Since 5FU acts by inhibition of thymidylate synthase (TS), resulting in inhibition of DNA synthesis, several new antifolates, directed towards TS, have been developed. However, these agents, such as ZD1694 (Tomudex, Raltitrexed) and LY231514 (MTA, multitargetted antifolate) showed only limited efficacy. Other new agents active in colorectal cancer, e.g. the topoisomerase I inhibitors topotecan and CPT-11, showed only minor activity. The same was observed for the taxanes. Combinations of gemcitabine (cisplatin, 5FU, epirubicin, marimastat) show promising activities, not only regarding response but also with respect to clinical benefit. The effects were better than that for each agent separately. Thus, despite limited activity of single agents, novel combinations especially with gemcitabine are promising, with emphasis on improvement of the clinical benefit of patients.

Phase I/pharmacokinetic study of the topoisomerase I inhibitor GG211 administered as a 21-day continuous infusion

BACKGROUND

Preclinical results support a prolonged schedule of administration for topoisomerase I inhibitors, and we have previously demonstrated the safety and activity of the novel water-soluble topoisomerase I inhibitor GG211 when given as a 72-hour continuous infusion to cancer patients.

PATIENTS AND METHODS

In a three-center international phase I trial, 38 patients received GG211 doses from 0.3 to 0.5 mg/m2/day by continuous intravenous infusions for seven, 14, and 21 days. Patients' median performance status was 1; nearly half had colorectal cancer, and 35 patients had prior chemotherapy.

RESULTS

The first patient cohort received 0.3 mg/m2/day for seven days with no significant toxicities. Subsequent cohorts received continuous infusions for 14 and 21 days at this dose level with only mild myelosuppression noted. Dose-escalation on the 21-day schedule was then performed. No dose-limiting toxicity occurred at the 0.4 mg/m2/day dose level. Thrombocytopenia was dose-limiting with 0.5 mg/m2/day dosing but was not cumulative. Other grade 3 4 toxicities included neutropenia, nausea, vomiting, diarrhea, and fatigue. Partial responses occurred with 21-day infusion in two patients with breast and ovarian cancer at the 0.3 and 0.4 mg/m2/day dose levels, respectively. Mean GG211 lactone Css ranged from 0.17 to 0.64 ng/ml.

CONCLUSION

The maximum tolerated dose of GG211 administered as a 21-day continuous infusion is 0.4 mg/m2/day with antitumor activity noted at tolerable doses.