A phase I trial of vertical inhibition of IGF signalling using cixutumumab, an anti-IGF-1R antibody, and selumetinib, an MEK 1/2 inhibitor, in advanced solid tumours

BACKGROUND

We completed a phase I clinical trial to test the safety and toxicity of combined treatment with cixutumumab (anti-IGF-1R antibody) and selumetinib (MEK 1/2 inhibitor).

METHODS

Patients with advanced solid tumours, refractory to standard therapy received selumetinib hydrogen sulphate capsules orally twice daily, and cixutumumab intravenously on days 1 and 15 of each 28-day cycle. The study used a 3+3 design, with a dose-finding cohort followed by an expansion cohort at the maximally tolerated dose that included pharmacokinetic and pharmacodynamic correlative studies.

RESULTS

Thirty patients were enrolled, with 16 in the dose-finding cohort and 14 in the expansion cohort. Grade 3 or greater toxicities included nausea and vomiting, anaemia, CVA, hypertension, hyperglycaemia, and ophthalmic symptoms. The maximally tolerated combination dose was 50 mg twice daily of selumetinib and 12 mg kg(-1) every 2 weeks of cixutumumab. Two patients achieved a partial response (one unconfirmed), including a patient with BRAF wild-type thyroid carcinoma, and a patient with squamous cell carcinoma of the tongue, and six patients achieved time to progression of >6 months, including patients with thyroid carcinoma, colorectal carcinoma, and basal cell carcinoma. Comparison of pre- and on-treatment biopsies showed significant suppression of pERK and pS6 activity with treatment.

CONCLUSIONS

Our study of anti-IGF-1R antibody cixutumumab and MEK 1/2 inhibitor selumetinib showed that the combination is safe and well-tolerated at these doses, with preliminary evidence of clinical benefit and pharmacodynamic evidence of target inhibition.

Evaluation of the novel mitotic modulator ON 01910.Na in pancreatic cancer and preclinical development of an ex vivo predictive assay

The pupose of this study was to evaluate the activity of ON 01910.Na, a mitotic inhibitor, in in vitro and in vivo models of pancreatic cancer and to discover biomarkers predictive of efficacy. Successive in vitro and in vivo models were used; these included cell line-derived and patient-derived tumors from our PancXenoBank, a live collection of freshly generated pancreatic cancer xenografts. ON 01910.Na showed equivalent activity to gemcitabine against pancreatic cancer cell lines in vitro. The activity of the agent correlated with suppression of phospho-CDC25C and cyclin B1. These markers were optimized for a fine-needle aspirate ex vivo rapid assay. Cyclin B1 mRNA evaluation yielded the most optimal combination of accuracy and reproducibility. Next, nine patient-derived tumors from the PancXenoBank were profiled using the assay developed in cell lines and treated with ON01910.Na for 28 days. Two cases were cataloged as potential responders and seven as resistants. There was a correlation between the ex vivo assay and sensitivity to the tested agent, as the two cases prospectively identified as sensitive met prespecified criteria for response. Of the seven tumors of predictive resistant, only one was found to be sensitive to ON 01910.Na. In addition, there was a good correlation between cyclin B1 downregulation ex vivo and changes in cyclin B1 protein post-treatment. The novel mitotic inhibitor, ON 01910.Na, showed activity in preclinical model of pancreatic cancer. A rapid assay was rationally developed that not only identified cases sensitive to ON 01910.Na, but also anticipated the pharmacodynamic events occurring after in vivo exposure.

Phase I study of troxacitabine administered by continuous infusion in subjects with advanced solid malignancies

BACKGROUND

Troxacitabine is a novel L-nucleoside analogue. Preclinical studies showed improved activity with infusions of at least 3 days compared with bolus regimens, especially at concentrations >20 ng/ml. This phase I study tested the feasibility of achieving a troxacitabine steady-state concentration of 20 ng/ml for at least 72 h in patients with solid tumors.

PATIENTS AND METHODS

Patients with solid tumors received troxacitabine as a progressively longer infusion on days 1-4 of a 28-day cycle. The initial length of infusion and infusion rate were 48 h and 3 mg/m(2)/day.

RESULTS

Twenty-one patients were treated at infusion lengths that increased from 48 to 72 h and then 96 h. The infusion rate was decreased from 3 to 1.88 mg/m(2)/day due to toxicity. Dose-limiting toxicities consisted of grade 4 neutropenia (three) and grade 3 constipation (one). The maximum tolerated dose of continuous infusion troxacitabine in patients with solid tumors is 7.5 mg/m(2) administered over 96 h. This dose level resulted in steady-state drug concentration of at least 20 ng/ml for 72 h.

CONCLUSIONS

Administration of troxacitabine by continuous infusion achieved the prospectively defined target plasma concentration. Pharmacokinetics (PK) modeling coupled with real-time PK assessment was an efficient approach to conduct hypothesis-driven phase I trials.

Phase I study of ABT-751 in combination with CAPIRI (capecitabine and irinotecan) and bevacizumab in patients with advanced colorectal cancer

13553

Background: ABT-751 (A) is an orally (PO) bioavailable sulfonamide with antimitotic properties. We are performing a non-randomized phase I/II dose-escalation study of A in combination with capecitabine (C), irinotecan (I) and bevacizumab (B) to define the maximum tolerated dose (MTD), dose-limiting toxicity (DLT), and pharmacokinetics (PK) in patients with advanced colorectal cancer (1st or 2nd line). Methods: Patients are treated with A QD for 7d (lead-in) and then begin 21-d cycles of treatment with A (QD) and C (BID) d1–14 PO, I d1 IV, and B d1 IV. Dose escalation started at dose level (DL) 1 at A 150 mg, I 200 mg/m2, and C 1600 mg/m2 (total daily dose) and escalated to full dose CAPIRI (I 250 mg/m2, and C 2000 mg/m2) for DL2. B was then added as standard of care at 7.5 mg/kg for DL2b (and later, DL1b). Blood samples were collected for pharmacogenomics (PG), pharmacodynamics (PD), steady-state PK of A and A metabolites when administered alone or in combination with C, I, and B, and PK of I and I metabolites. Serial dynamic contrast MRI’s, before and after the ABT-751 monotherapy lead-in period, are being performed in a subset of subjects. Results: Eight patients have been treated at dose levels 1 (3), 2 (2), and 2b (3). One patient on DL2 experienced g3 transaminitis and another on DL2b had F&N which were dose-limiting. Dose level 1 is being expanded to 6 patients, now with B (DL1b). Other g3/4 toxicities have included g4 neutropenia (1 subject DL2, 1 DL2b). The formation of A glucuronide appears decreased during combination therapy (see table). I PK, PD, and PG samples were collected and analysis is pending. Of 8 subjects, there have been 4 PD and 4 SD after 2 cycles. Conclusions: The combination therapy of A 150 mg and 20% dose-reduced CAPIRI appears well-tolerated. Patient accrual continues at DL1b. [Table: see text]

No significant financial relationships to disclose.

Phase I study of ON-01910.Na, a novel cell cycle inhibitor in adult patients with solid tumors

13026

Background: ON-1910.Na is a new chemical entity, novel cell cycle inhibitor which arrests cells in G2/M, affects phosphorylation of several regulatory kinases and lacks cross resistance to other standard chemotherapy agents. This is a first-in-man Phase I dose escalation study to determine the dose limiting toxicities, recommended Phase II dose, and pharmacokinetic (PK) profile, and to document any antitumor activity of ON-01910.Na. Methods: Patients had histologically confirmed solid tumors refractory to standard therapy. ON-1910.Na, formulated as a solution in PEG400, was administered as a 2-hour infusion on days 1, 4, 8, 11, 15, and 18 followed by a 10 day observation period for a total of 28 days per cycle. The initial dose was 80 mg and was escalated using an accelerated titration schedule; one patient was treated per cohort until grade 2 toxicity was documented. A dose confirmation cohort of up to 12 patients will be treated at the maximun tolerated dose (MTD). A comprehensive PK study was performed on days 1 and 15 of the first cycle, plus trough samples were collected. Results: Thirteen patients (7F, 6M; ages 46–73) have received 20 cycles. Dose levels of 80, 160, 320, 480, 800, 1280, 2080, and 3120 mg were evaluated in 8 patients, and a further dose of 4370 mg has been evaluated in 5 patients. Toxicities have been anemia (2 G1, 1 G2), leucopenia (1 G1, 1 G2), hyperglycemia (2 G1), elevated AST/ALT (1 G1, 1 G2), nausea (3 G1), diarrhea (3 G1), skeletal pain (5 G1, 1 G2), abdominal pain (2 G1), tumor pain (1 G2), and fatigue (3 G1, 1 G2), and have clustered at the latter 3 dose levels. PK analysis shows increasing ON-1910.Na exposure with increasing doses. ON-1910.Na has a low clearance (13 L/h), long half-life (20 h), distribution in excess of blood volume (58 L) and PK parameters are similar on days 1 and 15. Approximately 3-fold and 5-fold inter-subject variation in ON-1910.Na clearance was observed on days 1 and 15, respectively. No antitumor activity has been documented by standard criteria. Conclusions: Dose escalation is continuing.

[Table: see text]

Phase II study of flavopiridol in patients with advanced colorectal cancer

BACKGROUND

Flavopiridol, a synthetic flavone that inhibits cell cycle progression, has demonstrated activity in colon cancer in xenografts and in a phase I trial. We evaluated flavopiridol in a phase II trial in patients with previously untreated advanced colorectal cancer (ACRC).

PATIENTS AND METHODS

Twenty chemotherapy-naïve patients with ACRC received flavopiridol at a dose of 50 mg/m(2)/day via a 72-h continuous infusion every 14 days. Response was assessed by computed tomography or magnetic resonance imaging every 8 weeks.

RESULTS

Twenty patients were enrolled; 19 were evaluable for toxicity and 18 for response. There were no objective responses. Five patients had stable disease lasting a median of 7 weeks. The median time to progression was 8 weeks. Median survival was 65 weeks. The principal grade 3/4 toxicities were diarrhea, fatigue and hyperglycemia, occurring in 21%, 11% and 11% of patients, respectively. Other common toxicities included anemia, anorexia and nausea/vomiting.

CONCLUSIONS

Flavopiridol in this dose and schedule does not have single-agent activity in patients with ACRC. Recent preclinical data suggest that flavopiridol enhances apoptosis when combined with chemotherapy. Trials that evaluate flavopiridol in combination with active cytotoxic drugs should help to define the role of this novel agent in ACRC.

A phase I pharmacokinetic and pharmacodynamic study of the DNA methyltransferase 1 inhibitor MG98 administered twice weekly

BACKGROUND

Hypermethylation and inactivation of tumor suppressor genes by the enzyme DNA methyltransferase may lead to neoplastic transformation. MG98, a phosphorothioate antisense oligodeoxynucleotide that is a specific inhibitor of mRNA for human DNA methyltransferase 1 (DNMT1), was evaluated in a phase I study.

PATIENTS AND METHODS

MG98 was given as a 2 h i.v. infusion twice weekly three weeks out of every four to patients with solid tumors. Pharmacokinetic evaluation was performed on days 1 and 15 of cycle 1 and mRNA expression of DNMT1 was measured in peripheral blood mononuclear cells (PBMCs).

RESULTS

Nineteen patients were entered onto the study. A total of 74 cycles (range 1-18 cycles) were administered at dose levels from 40 to 480 mg/m(2). Dose limiting toxicity was seen in two of three patients at 480 mg/m(2) and consisted of a constellation of fever, chills, fatigue and, in one case, confusion beginning within 6 h after the first infusion. Other toxic effects included fatigue, anorexia, nausea, vomiting and diarrhea, reversible elevations in transaminases and partial thromboplastin time. Pharmacokinetic evaluation showed C(max) and AUC to be dose proportional with low inter- and intra-patient variability. No consistent changes in DNMT1 mRNA expression were noted in PBMCs. One partial response was documented in a patient with renal cell carcinoma treated at 80 mg/m(2).

CONCLUSIONS

The recommended dose of MG98 was 360 mg/m(2) given by 2 h infusion twice a week for three weeks out of every four. Phase II trials using this dose and schedule are underway.

Metabolism and urinary excretion of a new quinoline anticancer drug, TAS-103, in humans

1. TAS-103, a novel condensed quinoline derivative, has been developed as an anticancer drug targeting topoisomerases I and II. 2. The purpose of the present study was to characterize the metabolism and urinary excretion of TAS-103 after the intravenous infusion of a single dose to patients in Phase I clinical trials. 3. Five metabolites were detected using high-performance liquid chromatography (HPLC) photodiode array and a precursor scan by liquid chromatography mass spectrometry mass spectrometry (LC/MS/MS). 4. Structures of the five metabolites were determined using the results of enzymatic hydrolysis and the analysis of production mass spectra obtained by LC/MS/MS, and by comparing HPLC retention times and UV, mass and production mass spectra of authentic standards. 5. The metabolites were identified as demethyl-TAS-103 glucuronide (DM-TAS-103-G), TAS-103 glucuronide (TAS-103-G), TAS-103 glucuronide N-oxide (NO-TAS-103-G), demethyl-TAS-103 (DM-TAS-103) and TAS-103 N-oxide (NO-TAS-103). 6. The mean total amount of TAS-103 and TAS-103-G in urine was only 6.03% of the dose, suggesting that urine is not the main elimination route. TAS-103 was extensively metabolized, and a small percentage of the parent drug (0.41%) was found in urine.

Phase I trial of the matrix metalloproteinase inhibitor BAY12-9566 in patients with advanced solid tumors

PURPOSE

Matrix metalloproteinases (MMPs) are a family of proteolytic enzymes that are believed to be involved in primary and metastatic tumor growth by degrading the basement membrane and changing the extracellular matrix to facilitate invasion of malignant cells and angiogenesis. Overexpression of MMPs has been documented in various solid tumors. BAY12-9566 is a selective inhibitor of MMPs, in particular MMP-2, -3. and -9. The purpose of this trial was to define the maximum tolerated dose (MTD), dose-limiting toxicities (DLT), safety profile, pharmacokinetics and pharmacodynamics of orally administered BAY12-9566 in patients with incurable solid tumors.

METHODS

The starting dose of BAY12-9566 for this single institution, outpatient phase I study was 100 mg/day orally. Patients were allowed to receive drug for up to 12 months. A total of 27 patients with various solid malignancies including colorectal, breast, lung, cervical and ovarian cancers were enrolled at doses from 100 to 1,600 mg/day. Patients were evaluated weekly while on treatment. Relevant radiologic examination was performed every 8 weeks to document and follow sites of measurable or evaluable disease.

RESULTS

Toxicities from BAY12-9566 included liver injury test abnormalities, anemia, shoulder and back pain. thrombocytopenia, mild nausea and fatigue, diarrhea, rash and deep vein thrombosis. No toxicity greater than grade III was observed. As doses were increased from 100 to 400 to 1,600 mg/day, even in divided doses, less than proportional increases in AUC were observed. At the highest dose level of 1600 mg/day, the day 29 AUC (3778.00 mg x h/l) remained similar to the day 29 AUC (3312.60 mg x h/l) at the dose level of 1200 mg/day. No responses were seen, but 14 patients remained on study with stable disease for 4 to 26 months.

CONCLUSIONS

BAY12-9566 was well tolerated at doses as high as 800 mg orally twice daily. Although mild alterations in liver injury tests, platelet count and hematocrit were noted, these were not dose-limiting. The drug was well absorbed. However, the absence of proportional increases in AUC with doses greater than 800 mg and the achievement of Css in the range associated with biologic activity in preclinical models led to the selection of 800 mg twice daily for further evaluation in phase III trials.

A Phase I clinical and pharmacological evaluation of sodium phenylbutyrate on an 120-h infusion schedule

PURPOSE

Sodium phenylbutyrate (PB) demonstrates potent differentiating capacity in multiple hematopoietic and solid tumor cell lines. We conducted a Phase I and pharmacokinetic study of PB by continuous infusion to characterize the maximum tolerated dose, toxicities, pharmacokinetics, and antitumor effects in patients with refractory solid tumors.

PATIENTS AND METHODS

Patients were treated with a 120-h PB infusion every 21 days. The dose was escalated from 150 to 515 mg/kg/day. Pharmacokinetics were performed during and after the first infusion period using a validated high-performance liquid chromatographic assay and single compartmental pharmacokinetic model for PB and its principal metabolite, phenylacetate.

RESULTS

A total of 24 patients were enrolled on study, with hormone refractory prostate cancer being the predominant tumor type. All patients were evaluable for toxicity and response. A total of 89 cycles were administered. The dose-limiting toxicity (DLT) was neuro-cortical, exemplified by excessive somnolence and confusion and accompanied by clinically significant hypokalemia, hyponatremia, and hyperuricemia. One patient at 515 mg/kg/day and another at 345 mg/kg/day experienced this DLT. Toxicity resolved < or =12 h of discontinuing the infusion. Other toxicities were mild, including fatigue and nausea. The maximum tolerated dose was 410 mg/kg/day for 5 days. Pharmacokinetics demonstrated that plasma clearance of PB increased in a continuous fashion beginning 24 h into the infusion. In individuals whose V(max) for drug elimination was less than their drug-dosing rate, the active metabolite phenylacetate accumulated progressively. Plasma PB concentrations (at 410 mg/kg/day) remained above the targeted therapeutic threshold of 500 micromol/liter required for in vitro activity.

CONCLUSION

The DLT in this Phase I study for infusional PB given for 5 days every 21 days is neuro-cortical in nature. The recommended Phase II dose is 410 mg/kg/day for 120 h.

Bioavailability of penclomedine and systemic exposure to 4-O-demethylpenclomedine in patients receiving oral and intravenous penclomedine

PURPOSE

Oral administration of penclomedine was investigated based on preclinical studies indicating that an oral schedule of penclomedine treatment may prevent the neurotoxicity observed in phase I studies of an intravenous (i.v.) formulation, possibly by reducing maximum plasma concentrations (Cmax) of the neurotoxic parent species.

METHODS

Penclomedine was administered i.v. (200 mg/m2) and orally (250 mg/m2) in alternate sequences to patients with solid tumor malignancies. Plasma concentrations of parent drug and the principal metabolite, 4-O-demethylpenclomedine, were determined by a reversed-phase HPLC assay.

RESULTS

Penclomedine was detectable in the plasma of all patients within 1 h of oral penclomedine treatment and Cmax was reached within 1 to 4 h. Consistent with the hypothesis that an oral schedule of administration may circumvent neurotoxicity, a paired data analysis demonstrated a significant reduction in Cmax values following oral administration (P=0.017). However the magnitude of this reduction was highly variable. Similarly an extensive range in the relative exposure to both parent drug and metabolite were observed. The bioavailability of penclomedine ranged from 28% to 98% (median 73%).

CONCLUSIONS

Oral penclomedine does produce systemic exposure, but substantial interpatient variability in absorption and systemic exposure is present which may limit the clinical role of the oral route of administration.

A phase I dose escalation and bioavailability study of oral sodium phenylbutyrate in patients with refractory solid tumor malignancies

PURPOSE

Phenylbutyrate (PB) is an aromatic fatty acid with multiple mechanisms of action including histone deacetylase inhibition. Preclinically, PB demonstrates both cytotoxic and differentiating effects at a concentration of 0.5 mM. We conducted a Phase I trial of p.o. PB patients with refractory solid tumor malignancies to evaluate toxicity, pharmacokinetic parameters, and feasibility of p.o. administration.

EXPERIMENTAL DESIGN

Twenty-eight patients with refractory solid tumor malignancies were enrolled on this dose-escalation to maximally tolerated dose trial. Five dose levels of PB were studied: 9 g/day (n = 4), 18 g/day (n = 4), 27 g/day (n = 4), 36 g/day (n = 12), and 45 g/day (n = 4). Pharmacokinetic studies were performed and included an p.o. bioavailability determination. Compliance data were also collected.

RESULTS

The recommended Phase II dose is 27 g/day. Overall the drug was well tolerated with the most common toxicities being grade 1-2 dyspepsia and fatigue. Nonoverlapping dose-limiting toxicities of nausea/vomiting and hypocalcemia were seen at 36 g/day. The p.o. bioavailability of PB was 78% for all dose levels, and the biologically active concentration of 0.5 mM was achieved at all dose levels. Compliance was excellent with 93.5% of all possible doses taken. No partial remission or complete remission was seen, but 7 patients had stable disease for more than 6 months while on the drug.

CONCLUSIONS

PB (p.o.) is well tolerated and achieves the concentration in vivo that has been shown to have biological activity in vitro. PB may have a role as a cytostatic agent and should be additionally explored in combination with cytotoxics and other novel drugs.

Impact of the putative differentiating agent sodium phenylbutyrate on myelodysplastic syndromes and acute myeloid leukemia

Sodium phenylbutyrate (PB) is an aromatic fatty acid with cytostatic and differentiating activity against malignant myeloid cells (ID(50), 1-2 mM). Higher doses induce apoptosis. Patients with myelodysplasia (n = 11) and acute myeloid leukemia (n = 16) were treated with PB as a 7-day continuous infusion repeated every 28 days in a Phase I dose escalation study. The maximum tolerated dose was 375 mg/kg/day; higher doses led to dose-limiting reversible neurocortical toxicity. At the maximum tolerated dose, PB was extremely well tolerated, with no significant toxicities; median steady-state plasma concentration at this dose was 0.29 +/- 0.16 mM. Although no patients achieved complete or partial remission, four patients achieved hematological improvement (neutrophils in three, platelet transfusion-independence in one). Other patients developed transient increases in neutrophils or platelets and decrements in circulating blasts. Monitoring of the percentage of clonal cells using centromere fluorescence in situ hybridization over the course of PB administration showed that hematopoiesis remained clonal. Hematological response was often associated with increases in both colony-forming units-granulocyte-macrophage and leukemic colony-forming units. PB administration was also associated with increases in fetal erythrocytes. These data document the safety of continuous infusion PB and provide preliminary evidence of clinical activity in patients with myeloid malignancies.

Phase II study of 4-ipomeanol, a naturally occurring alkylating furan, in patients with advanced hepatocellular carcinoma

BACKGROUND/PURPOSE

4-Ipomeanol (IPO; NSC 394438), a naturally occurring furan isolated from common sweet potatoes (Ipomoea batatas) infected with the fungus Fusarium solani was the first agent to be developed by the National Cancer Institute based on a biochemical-biological rationale as an anticancer agent targeted specifically against lung cancer. Prior to clinical development, IPO was shown to induce pulmonary toxicity in the lungs of several mammalian species because the agent is metabolized to a highly reactive furan epoxide by specific cytochrome P450 monooxygenases found in pulmonary Clara cells and type II pneumocytes, which share biochemical features with bronchogenic carcinoma. However, instead of inducing the anticipated lung toxicity in patients with lung cancer in disease-directed phase I studies, hepatotoxicity was the principal toxic effect of IPO in humans. Based on the presumption that IPO may be preferentially activated by cytochrome P450 monooxygenases in liver cells and biochemically-related hepatic malignancies, a phase II study was conducted to determine the activity and evaluate the toxicity of IPO in patients with advanced hepatocellular carcinoma.

PATIENTS AND METHODS

Nineteen patients with advanced measurable hepatocellular carcinoma were enrolled on the phase II trial. All patients had an Eastern Cooperative Oncology Group performance status of at least two, no evidence of pulmonary dysfunction, and had either no prior treatment or minimal prior therapy. Patients were treated with IPO at a dose of either 1032 mg/m2, which was the maximum tolerated and recommended phase II dose previously derived for patients with normal hepatic function (15 patients) or 826 mg/m2 if they had serum bilirubin concentrations in the range of 2.0 to 3.0 mg/dL (four patients). Treatment was repeated every three weeks. Objective tumor response, the primary endpoint of the study, was assessed after every two courses of treatment, and both pulmonary function and lung density were rigorously monitored using successive pulmonary function testing and computerized tomography.

RESULTS

All nineteen patients were evaluable for both response and toxicity. No major objective responses were observed. One patient had a minor, brief reduction in lung metastases. Although marker lesions and overall disease remained stable for at least 12 and 24 months in three and two patients, respectively, the median time to progression was three months and the median survival was five months for all patients. The principal toxicity was reversible elevations in hepatic transaminases, which occasionally resulted in dose reduction. No clinically-significant pulmonary toxicity was noted.

CONCLUSION

IPO at a dose of either 826 or 1032 mg/m2 administered every three weeks did not demonstrate a relevant degree of clinical activity against advanced hepatocellular carcinoma. Further evaluations of TO is not recommended for this disease.

Tumor targeting by conjugation of DHA to paclitaxel

Targeting an anti-cancer drug to tumors should increase the Area Under the drug concentration-time Curve (AUC) in tumors while decreasing the AUC in normal cells and should therefore increase the therapeutic index of that drug. Anti-tumor drugs typically have half-lives far shorter than the cell cycle transit times of most tumor cells. Tumor targeting, with concomitant long tumor exposure times, will increase the proportion of cells that move into cycle when the drug concentration is high, which should result in more tumor cell killing. In an effort to test that hypothesis, we conjugated a natural fatty acid, docosahexaenoic acid (DHA), through an ester bond to the paclitaxel 2'-oxygen. The resulting paclitaxel fatty acid conjugate (DHA-paclitaxel) does not assemble microtubules and is non-toxic. In the M109 mouse tumor model, DHA-paclitaxel is less toxic than paclitaxel and cures 10/10 tumored animals, whereas paclitaxel cures 0/10. One explanation for the conjugate's greater therapeutic index is that the fatty acid alters the pharmacokinetics of the drug to increase its AUC in tumors and decrease its AUC in normal cells. To test that possibility, we compared the pharmacokinetics of DHA-paclitaxel with paclitaxel in CD2F1 mice bearing approximately 125 mg sc M109 tumors. The mice were injected at zero time with a bolus of either DHA-paclitaxel or paclitaxel formulated in 10% cremophor/10% ethanol/80% saline. Animals were sacrificed as a function of time out to 14 days. Tumors and plasma were frozen and stored. The concentrations of paclitaxel and DHA-paclitaxel were analyzed by LC/MS/MS. The results show that DHA targets paclitaxel to tumors: tumor AUCs are 61-fold higher for DHA-paclitaxel than for paclitaxel at equitoxic doses and eight-fold higher at equimolar doses. Likewise, at equi-toxic doses, the tumor AUCs of paclitaxel derived from i.v. DHA-paclitaxel are 6.1-fold higher than for paclitaxel derived from i.v. paclitaxel. The tumor concentration of paclitaxel derived from i.v. paclitaxel drops rapidly, so that by 16 h it has fallen to the same concentration (2.8 microM) as after an equi-toxic concentration of DHA-paclitaxel. In plasma, paclitaxel AUC after an MTD dose of DHA-paclitaxel is approximately 0.5% of DHA-paclitaxel AUC. Thus, the increase in tumor AUC and the limited plasma AUC of paclitaxel following DHA-paclitaxel administration are consistent with the increase in therapeutic index of DHA-paclitaxel relative to paclitaxel in the M109 mouse tumor model. A phase I clinical study has been completed at The Johns Hopkins Hospital to evaluate the safety of DHA-paclitaxel in patients with a variety of solid tumors. Twenty-one patients have been treated to date. The recommended phase II dose is 1100 mg/m(2), which is equivalent to 4.6 times the maximum approved paclitaxel dose on a molar basis. No alopecia or significant peripheral neuropathy, nausea, or vomiting have been observed. Asymptomatic, transient neutropenia has been the primary side effect. Eleven of 22 evaluable phase I patients transitioned from progressive to stable disease, as assessed by follow-up CT. Significant quality of life improvements have been observed. Thus, DHA-paclitaxel is well tolerated in patients and cures tumors in mice by targeting drug to tumors.

Novel allogeneic granulocyte-macrophage colony-stimulating factor-secreting tumor vaccine for pancreatic cancer: a phase I trial of safety and immune activation

PURPOSE

Allogeneic granulocyte-macrophage colony-stimulating factor (GM-CSF)-secreting tumor vaccines can cure established tumors in the mouse, but their efficacy against human tumors is uncertain. We have developed a novel GM-CSF-secreting pancreatic tumor vaccine. To determine its safety and ability to induce antitumor immune responses, we conducted a phase I trial in patients with surgically resected adenocarcinoma of the pancreas.

PATIENTS AND METHODS

Fourteen patients with stage 1, 2, or 3 pancreatic adenocarcinoma were enrolled. Eight weeks after pancreaticoduodenectomy, three patients received 1 x 10(7) vaccine cells, three patients received 5 x 10(7) vaccine cells, three patients received 10 x 10(7) vaccine cells, and five patients received 50 x 10(7) vaccine cells. Twelve of 14 patients then went on to receive a 6-month course of adjuvant radiation and chemotherapy. One month after completing adjuvant treatment, six patients still in remission received up to three additional monthly vaccinations with the same vaccine dose that they had received originally.

RESULTS

No dose-limiting toxicities were encountered. Vaccination induced increased delayed-type hypersensitivity (DTH) responses to autologous tumor cells in three patients who had received >or= 10 x 10(7) vaccine cells. These three patients also seemed to have had an increased disease-free survival time, remaining disease-free at least 25 months after diagnosis.

CONCLUSION

Allogeneic GM-CSF-secreting tumor vaccines are safe in patients with pancreatic adenocarcinoma. This vaccine approach seems to induce dose-dependent systemic antitumor immunity as measured by increased postvaccination DTH responses against autologous tumors. Further clinical evaluation of this approach in patients with pancreatic cancer is warranted.

Intensified adjuvant combined modality therapy for resected periampullary adenocarcinoma: acceptable toxicity and suggestion of improved 1-year disease-free survival

PURPOSE

(1) To determine the toxicity of an intensified postoperative adjuvant regimen for periampullary adenocarcinoma (pancreatic and nonpancreatic) utilizing concurrent 5-fluorouracil (5-FU), leucovorin (LV), dipyridamole (DPM), and mitomycin-C (MMC) combined with split-course locoregional external beam radiotherapy (EBRT) to 50 Gy. This was followed by 4 cycles of the same chemotherapy as adjuvant therapy. (2) To determine preliminary estimates of the overall and disease-free survival associated with the use of this regimen. (3) To compare the toxicities and early survival results of patients treated with the current regimen to those of patients who completed our prior trial of concurrent chemoradiation infusion with 5-FU/LV chemotherapy and regional nodal and prophylactic hepatic irradiation.

METHODS

Postpancreaticoduodenectomy, patients received every 4 weeks bolus administration of 5-FU, (400 mg/m(2)), and LV, (20 mg/m(2), Days l-3), DPM (75 mg p.o., 4 times per day, Days 0-3, and every 8 weeks), MMC, (10 mg/m(2); maximum of 20 mg, Day l during EBRT). This was followed by 4 months of the same chemotherapy, beginning 1 month following the completion of EBRT. EBRT consisted of split-course 5000 cGy/20 fractions with a 2-week planned rest after the first 10 fractions (2500 cGy).

RESULTS

From 4/96 to 6/99, 45 patients were enrolled and treated. Their experience constitutes the basis of this analysis. There were 29 patients with pancreatic cancer and 16 with nonpancreatic periampullary cancer. Seventeen patients had tumors of 3 cm or more, and 39 patients had at least 1 histologically involved lymph node. Thirteen patients had a histologically positive margin of resection. The mean time to start of treatment was 63 days following surgery. During chemoradiation therapy there were no Grade 3 or worse nonhematologic toxicities and 47% Grade 3 or Grade 4 hematologic toxicities of short duration. Following chemoradiation, during chemotherapy treatment only, there was one Grade 3 hepatic and one Grade 3 pulmonary toxicity which was nondebilitating (2% each case) and 42% Grade 3 or 4 hematologic toxicity. There were 2 episodes of neutropenic fever requiring admission and no treatment-related mortalities. One patient developed a mild case of HUS, which responded to standard management. One patient developed persistent shortness of breath (nondebilitating), and another patient had occasional dyspnea on exertion, both occurring after all therapy. The majority of patients complained of increased fatigue (Grade 1-2), greatest during the combined therapy and improving post all treatment. As of 6/23/99, 20 of 45 patients have relapsed, 13 in the liver. Twelve patients have died. Median follow-up for surviving patients is 14.3 months. Disease-free survival at 12 months following surgery is 66% (as compared to 25% in our prior study), and the median disease-free survival is 17 months (as compared to 8. 3 months in our prior study). Median survival has not yet been reached, but will be greater than 17 months.

CONCLUSION

With a 14.3-month median follow-up, acute toxicity has been acceptable and manageable. Observed relapses were seen 9-13 months following surgical resection. Early survival analysis suggests a trend toward increased median disease-free survival (8.3 vs. 17 months), especially for patients with nonpancreatic periampullary adenocarcinoma.

Role of oral chemotherapy in colorectal cancer

Despite the long clinical history of 5-FU in gastrointestinal cancer, the development of oral agents has been a productive endeavor, and oral fluoropyrimidine agents are likely to play an important role in the management of colorectal cancer. Results of recent trials in advanced/metastatic colorectal cancer have shown equivalence of response rates, time to disease progression, and median survival and reduced rates of neutropenia and stomatitis with oral capecitabine (Xeloda) or UFT/leucovorin compared with standard fluorouracil (5-FU)/leucovorin regimens. Evaluation of these oral agents in adjuvant therapy, in combination chemotherapy, and in combination with radiation therapy is ongoing.

A phase I and pharmacologic evaluation of the DNA intercalator CI-958 in patients with advanced solid tumors

5-[(2-Aminoethyl)amino]-2-[2-(diethylamino)ethyl]-2H-[1]benzothiopyra no[4,3,2-cd]-indazol-8-ol trihydrochloride (CI-958) is the most active member of a new class of DNA intercalating compounds, the benzothiopyranoindazoles. Because of its broad spectrum and high degree of activity as well as a favorable toxicity profile in preclinical models, CI-958 was chosen for further development. The Phase I study described here was undertaken to determine the toxicity profile, maximum tolerated dose, and pharmacokinetics of CI-958 given as an i.v. infusion every 21 days. Adult patients with advanced refractory solid tumors who had adequate renal, hepatic, and hematological function, life expectancy, and performance status were eligible for this study. Written informed consent was obtained from all patients. Patients received a 1- or 2-h infusion of CI-958 at 21-day intervals. The starting dose was 5.2 mg/m2, and at least three patients were evaluated at each dose level before proceeding to a new dose level. A pharmacokinetically guided dose escalation design was used until reaching a predetermined target area under the plasma concentration versus time curve (AUC), after which a modified Fibonacci scheme was used. Forty-four patients (21 men and 23 women; median age, 59 years) received 162 courses of CI-958. Neutropenia and hepatorenal toxicity were the dose-limiting toxicities, which defined the maximum tolerated dose of CI-958 to be 875 mg/m2 when given as a 2-h infusion every 21 days. There were no tumor responses. Two patients had stable disease for >250 days. The recommended Phase II dose is 560 mg/m2 for patients with significant prior chemotherapy and 700 mg/m2 for patients with minimal prior chemotherapy. Pharmacokinetic analysis of plasma and urine concentration-time data from each patient was performed. At the recommended Phase II dose of 700 mg/m2, mean CI-958 clearance was 370 ml/min/m2, mean AUC was 33800 ng-h/ml, and mean terminal half-life (t1/2) was 15.5 days. The clearance was similar at all doses, and plasma CI-958 AUC increased proportionally with dose, consistent with linear pharmacokinetics. The percentage reduction in absolute neutrophil count from baseline was well predicted by AUC using a simple Emax model. The pharmacokinetically guided dose escalation saved five to six dose levels in reaching the maximum tolerated dose compared with a standard dose escalation scheme. This may represent the most successful application to date of this dose escalation technique.

A prospective pharmacologic evaluation of age-related toxicity of adjuvant chemotherapy in women with breast cancer

Despite increasing evidence of benefit from adjuvant chemotherapy, older women with breast cancer are commonly given less aggressive treatment than younger patients. Conflicting prior data regarding age-related toxicity prompted this prospective study. Forty-four women (aged 35-79 years) with early-stage breast cancer were treated with four cycles of adjuvant therapy with doxorubicin 60 mg/m2 i.v. and cyclophosphamide 600 mg/m2 i.v. every 21 days. They were monitored for myelosuppression, cardiotoxicity, and decrease in quality of life. Pharmacokinetics were analyzed using cycle 1 plasma samples. Bone marrow granulocyte and macrophage colony-forming units (CFU-GM) were assayed in vitro for dose response to 4-hydroperoxycyclophosphamide and doxorubicin before cycle 1. There was moderate evidence of age-related decrease in nadir absolute neutrophil count (ANC) when age was viewed as a continuous variable. On average there was a 10/microliter drop in cycle 1 nadir ANC for every year increase in age (p = 0.02). However, when age was viewed as a categorical variable (age < 65 vs. > or = 65 years), a similar proportion of women in each group reached an ANC < 100 (18% vs. 19%). Neither neutropenic complications, alteration in cardiac function, nor change in quality of life scores were significantly age related (p > 0.12). Pharmacokinetic analyses did not demonstrate age-related differences in the clearance of either doxorubicin or cyclophosphamide (p > 0.8). Pharmacodynamic analysis of individual patient bone marrow progenitor cell sensitivity did not reveal any correlation with age (p > 0.48). In women undergoing adjuvant therapy for breast cancer, no clinically significant age-related trends in toxicity were observed. These data suggest that older age alone should not exclude patients from receiving adjuvant therapy with doxorubicin and cyclophosphamide.

Phase I and pharmacologic study of oral fluorouracil on a chronic daily schedule in combination with the dihydropyrimidine dehydrogenase inactivator eniluracil

PURPOSE

To determine the maximum-tolerated dose (MTD), toxicities, and pharmacokinetics of oral fluorouracil (5-FU) administered twice daily in combination with oral eniluracil, an inactivator of dihydropyrimidine dehydrogenase, administered for 28 days every 35 days.

PATIENTS AND METHODS

Oral 5-FU 1.35 mg/m(2) twice daily was administered with oral eniluracil 10 mg daily for 14 to 28 days, followed by a 1-week rest period. Eniluracil was started 1 day before 5-FU. Patients then received escalated doses of oral 5-FU 1. 35 to 1.8 mg/m(2) twice daily with an increased dose of eniluracil 10 mg twice daily for 28 days. A reduced dose of 5-FU 1.0 mg/m(2) with eniluracil 20 mg twice daily was evaluated.

RESULTS

Thirty-six patients with solid malignancies were enrolled onto the study. Diarrhea was the principal dose-limiting toxicity of oral 5-FU and eniluracil given on this chronic schedule. The recommended phase II dose is 5-FU 1.0 mg/m(2) twice daily with eniluracil 20 mg twice daily. Mean (SD) values for terminal half-life, apparent volume of distribution, and systemic clearance of 4.5 hours (0.83 hours), 19 L/m(2) (3.0 L/m(2)), and 51 mL/min/m(2) (13 mL/min/m(2)), respectively. An average of 77% of 5-FU was excreted unchanged in urine after 28 days of treatment. The mean (range) 5-FU C(SS,min) values achieved at the 1.0 mg/m(2) dose level were 22 ng/mL (8 to 38 ng/mL).

CONCLUSION

Chronic oral administration of 5-FU with oral eniluracil is tolerable and produces 5-FU steady-state concentrations similar to those achieved with protracted intravenous administration of 5-FU on clinically relevant dose schedules. Eniluracil provides an attractive means of administering 5-FU on protracted schedules.

Laparoscopic retroperitoneal lymph node dissection for clinical stage I nonseminomatous germ cell testicular tumors

OBJECTIVES

To assess retrospectively whether laparoscopic retroperitoneal lymph node dissection (RPLND) in patients with clinical Stage I nonseminomatous germ cell testicular tumor (NSGCT) provides useful pathologic staging information on which subsequent management can be based. Approximately 30% of patients with clinical Stage I NSGCT will have pathologic Stage II disease.

METHODS

A retrospective review of 29 patients with clinical Stage I NSGCT who underwent transperitoneal laparoscopic RPLND by a single surgeon was performed. Selection criteria included the presence of embryonal carcinoma in the primary tumor or vascular invasion. A modified left (n = 18) or right (n = 11) template was used.

RESULTS

Positive retroperitoneal nodes were detected in 12 (41%) of 29 patients. Ten of these patients received immediate adjuvant platinum-based chemotherapy, and 2 patients refused chemotherapy. The nodes were negative in 1 7 (59%) of 29 patients; all but 2 patients (one with recurrence in the chest, the other with biochemical recurrence) have undergone observation. No evidence of disease recurrence has been found in the retroperitoneum of any patient (follow-up range 1 to 65 months). Prospectively, the dissection was limited if grossly positive nodes were encountered; therefore, the total number of nodes removed was significantly different if the nodes were positive or negative (14 +/- 2 and 25 +/- 3, respectively; P <0.004). Two patients required an open conversion because of hemorrhage. Complications included lymphocele (n = 1) and flank compartment syndrome (n = 1).

CONCLUSIONS

Laparoscopic RPLND is a feasible, minimally invasive surgical alternative to observation or open RPLND for Stage I NSGCT. Disease outcomes are favorable to date. Longer follow-up in a larger series is necessary to determine therapeutic efficacy.

Long term follow-up of women treated with 16-week, dose-intensive adjuvant chemotherapy for high risk breast carcinoma

BACKGROUND

A Phase II study was performed evaluating the disease free and overall survival rates associated with a dose-intensive, 16-week, doxorubicin-based adjuvant chemotherapy regimen in women with breast carcinoma and > or = 10 involved axillary lymph nodes.

METHODS

Eligible patients underwent staging with computed tomography and bone scanning and were treated with a 16-week, dose-intensive chemotherapy regimen, comprised of 8 2-week courses of cyclophosphamide, 100 mg/m2 orally, on Days 1-7; doxorubicin, 40 mg/m2 intravenously (i.v.), on Day 1; methotrexate, 100 mg/m2 i.v., on Day 1 with leucovorin rescue, 10 mg/m2, every 6 hours for 6 doses orally on Day 2; vincristine, 1 mg i.v. on Day 1; 5-fluorouracil (5-FU), 600 mg/m2 i.v., on Day 2 over 2 hours; and 5-FU, 300 mg/m2/day continuous i.v. on Days 8 and 9. Tamoxifen, 20 mg daily, was administered to patients with estrogen receptor positive tumors treated after October 1988. All patients were offered locoregional radiation therapy.

RESULTS

Sixty-four women were treated on protocol. The median follow-up of 27 surviving patients was > 8 years at last follow-up. Three patients were lost to follow-up. The median time to progression was 54 months, the Kaplan-Meier estimate of event free survival at 5 years was 44% (95% confidence interval [CI], 31-56%), and the Kaplan-Meier estimate of overall survival at 5 years was 57% (95% CI, 44-69%). At 98 months the Kaplan-Meier estimate of freedom from recurrence was 31% (95% CI, 19-43%) and the Kaplan-Meier estimate of survival at 111 months was 36% (95% CI, 23-49%).

CONCLUSIONS

Despite the use of dose-intensive, doxorubicin-based, adjuvant chemotherapy, and intensive staging prior to study entry, the results of the current study are similar to those of previous reports for standard dose chemotherapy and appear inferior to those reported for high dose therapy.

Absorption, metabolism, and excretion of 14C-temozolomide following oral administration to patients with advanced cancer

The purpose of this study is to characterize the absorption, metabolism, and excretion of carbon 14-labeled temozolomide (14C-TMZ) administered p.o. to adult patients with advanced solid malignancies. On day 1 of cycle 1, six patients received a single oral 200-mg dose of 14C-TMZ (70.2 microCi). Whole blood, plasma, urine, and feces were collected from days 1-8 and on day 14 of cycle 1. Total radioactivity was measured in all samples. TMZ, 5-(3-methyltriazen-1-yl)imidazole-4-carboxamide (MTIC), and 4-amino-5-imidazole-carboxamide (AIC) concentrations were determined in plasma, and urine and plasma samples were profiled for metabolite/degradation products. Maximum TMZ plasma concentrations were achieved between 0.33 to 2 h (mean, 1.2 h), and half-life, apparent volume of distribution, and oral clearance values averaged 1.9 h, 17 liters/m2, and 104 ml/min/m2, respectively. A first-order absorption, one-compartment linear model, which included first-order formation of MTIC from TMZ and elimination of MTIC via degradation to AIC, and a peripheral distribution compartment for AIC, adequately described the plasma TMZ, MTIC, and AIC concentrations. MTIC systemic clearance was estimated to be 5384 ml/min/m2, and the half-life was calculated to be 2.5 min. Metabolite profiles of plasma at 1 and 4 h after treatment showed that 14C-derived radioactivity was primarily associated with TMZ, and a smaller amount was attributed to AIC. Profiles of urine samples from 0-24 h revealed that 14C-TMZ-derived urinary radioactivity was primarily associated with unchanged drug (5.6%), AIC (12%), or 3-methyl-2,3-dihydro-4-oxoimidazo[5,1-d]tetrazine-8-carboxyl ic acid (2.3%). The recovered radioactive dose (39%) was principally eliminated in the urine (38%), and a small amount (0.8%) was excreted in the feces. TMZ exhibits rapid oral absorption and high systemic availability. The primary elimination pathway for TMZ is by pH-dependent degradation to MTIC and further degradation to AIC. Incomplete recovery of radioactivity may be explained by the incorporation of AIC into nucleic acids.

A phase II "window" study of topotecan in untreated patients with high risk adult acute lymphoblastic leukemia

To further evaluate the activity of topotecan (TPT) in acute leukemia, TPT was administered (2.1 mg/m2/day for 5 days by continuous i.v. infusion) to adult patients with previously untreated acute lymphoblastic leukemia (ALL) with high-risk features (13 patients) or relapsed ALL (1 patient). Patients achieving a partial response or significant hematological improvement received a second course. All patients subsequently received standard treatment for ALL. Because complete response was achieved in only 1 of 14 patients, the study was terminated prematurely. An additional patient achieved minimal response, and a third patient normalized her hemogram despite ongoing leukemia in the marrow. Overall, six patients had significant hematological improvement (normalization of platelet and/or absolute neutrophil count). Two patients expired due to infections during induction chemotherapy. The primary nonhematological toxicities were mucositis and diarrhea. Exposure to TPT did not appear to influence the response to subsequent standard chemotherapy. The mean steady-state TPT plasma concentration, 16.1+/-1 nM, overlapped the range of LD90 values of primary human leukemia specimens. Cellular topo I content varied over a 3-fold range, encompassing levels found previously in relapsed patients. No relationship was found between topo I expression and markers of cellular proliferation or response to therapy. In contrast, low expression of the apoptosis inhibitor Bcl-2 was associated with response to TPT therapy. TPT has significant, albeit modest, single-agent activity against high-risk adult ALL. This study demonstrates the feasibility of evaluating promising new therapeutic agents in untreated patients with acute leukemia at high risk for failure with conventional therapy.

Sequence-dependent hematological toxicity associated with the 3-hour paclitaxel/cyclophosphamide doublet

Paclitaxel is active in metastatic breast cancer. Combination studies have demonstrated complex interactions between paclitaxel and other cytotoxic agents, including sequence-dependent cytotoxic, toxicological, and pharmacological effects. The principal objectives of this study were to determine the maximum tolerated doses of paclitaxel (3-h infusion) and cyclophosphamide (1-h infusion) administered every 3 weeks with granulocyte colony-stimulating factor (Filgrastim) and to determine if the sequence-dependent toxicological effects that have previously been observed with this combination when paclitaxel was administered over 24 h were evident when paclitaxel was administered over 3 h. Fifteen women with metastatic breast cancer were treated. Starting doses were 200 mg/m2 paclitaxel and 1600 mg/m2 cyclophosphamide, with granulocyte colony-stimulating factor (5 micrograms/kg/day) given s.c. beginning 24 h after chemotherapy. Doses of both drugs were escalated in cohorts of at least four patients. The sequence of drug administration was alternated with each consecutive patient and with each subsequent course of therapy in each individual patient, enabling the evaluation of sequence-dependent toxicological and pharmacological effects. Severe myelosuppression was the principal dose-limiting toxicity for this regimen, precluding dose escalation above 200 mg/m2 paclitaxel and 1600 mg/m2 cyclophosphamide, the maximum tolerated dose for this combination on this schedule. As has been previously demonstrated with this combination, when paclitaxel is administered over 24 h, the hematopoietic toxicity was sequence dependent. Paired analysis of toxicity data using each patient as her own control indicated more severe hematological toxicity in courses in which paclitaxel was administered first. There was no evidence of sequence-dependent effects on the pharmacokinetics of these drugs that might account for this phenomenon. The impact of drug sequencing on toxicity should be considered in the further development of combination therapy containing alkylating agents and paclitaxel, when the latter is administered over 3 h.

High-dose topotecan with granulocyte-colony stimulating factor in fluoropyrimidine-refractory colorectal cancer: a phase II and pharmacodynamic study

PURPOSE

The premise for this study was that topotecan (TPT) resistance in preclinical studies is associated with low level expression of the p-glycoprotein (Pgp) multi-drug transporter conferred by the multi-drug resistant (MDR) phenotype, which might be overcome in clinical practice by administering moderately (2.3-fold) higher doses of TPT that have shown to be feasible with granulocyte colony-stimulating factor (G-CSF) support. This phase II study evaluated the anti-tumor activity of TPT administered at its highest possible solid tumor dose with G-SCF in patients with fluoropyrimidine-refractory advanced colorectal carcinoma. The study also sought to identify pharmacodynamic (PD) determinants of both activity and toxicity.

PATIENTS AND METHODS

TPT was administered as a 30-minute infusion daily for five days every three weeks at a dose of 3.5 mg/m2/day to patients with advance colorectal carcinoma who developed progressive disease either during treatment with fluoropyrimidine-based chemotherapy for advanced disease or within six months after receiving fluoropyrimidine-based adjuvant chemotherapy. This dose of TPT was previously determined to be the maximal tolerated dose (MTD) with G-CSF support in a phase I study involving solid tumor patients with similar risk factors for myelosuppression. Plasma sampling with performed during course 1 to characterize the pharmacokinetic (PK) and PD behavior of TPT.

RESULTS

Seventeen patients who received 89 courses of TPT and G-CSF were evaluable for toxicity; 16 patients were evaluable for anti-tumor response. Toxicity, particularly myelosuppression, was substantial. At the 3.5 mg/m2/day dose level, absolute neutrophil counts (ANC) were less than 500/microliters for longer than 5 days in 17% of courses involving seven of seventeen (41%) patients. Severe neutropenia associated with fever occurred in 12.3% of courses; and platelet counts below 25,000/microliters were noted in 26.9% of courses. These toxicities resulted in dose reductions in seven of 17 (41%) patients. Nevertheless, 90% of the planned total dose of TPT was administered. No major responses were observed, though minor activity was noted in several patients. Both the median time to progression and the median survival time were short--2.5 and 4 months respectively. Although interindividual variability in the disposition of total TPT was observed, the lack of objective responses precluded PD assessments related to disease activity. Total TPT exposure was significantly higher than drug exposure achieved in similar patients at an identical dose in a previous phase I study of TPT and G-CSF, which may explain why more severe myelosuppressive effects occurred in the present study. There were no PD relationships evident between relevant PK parameters and the percent decrements in platelets and ANC's during course 1, although patients with severe toxic effects (ANC below 500/microliters for more than five days and/or platelets < 25,000/microliters) had higher drug exposure than patients with less severe toxicity (P < 0.018 and P = 0.09, respectively).

CONCLUSIONS

Based on these results, the true response rate of TPT at its solid tumor MTD with G-CSF support is unlikely to approach 20%. Although a response rate of less than 20% might be viewed as significant in this disease setting and might be confirmed with sufficient statistical certainty by treating additional patients, the substantial toxicity, inconvenience, and cost associated with this high dose TPT/G-CSF regimen does not warrant the acceptance of a lower level of anti-tumor activity as a criterion for further development.

A phase I and pharmacologic study of DMP 840 administered by 24-hour infusion

PURPOSE

DMP 840, a novel bisnaphthalimide, has demonstrated promising schedule dependent anti-tumor activity in vitro and in vivo against several tumor cell lines. A phase I study was conducted to evaluate the effect of a 24-hour infusion schedule repeated every three weeks, on the therapeutic efficacy of DMP 840.

PATIENTS AND METHODS

Fourteen patients with refractory solid tumor malignancies were treated with DMP 840 at doses of 20, 40, 50 and 60 mg/m2.

RESULTS

A combination of neutropenia, thrombocytopenia and stomatitis were dose-limiting at doses of 50 and 60 mg/m2 in both minimally- and extensively-pretreated patients. In contrast, all courses at lower dose levels were well tolerated. Pharmacokinetic analysis demonstrated that DMP 840 had a prolonged terminal half life (median 39 hours; range 25-86) and that dose-limiting events were significantly related to several indices of systemic DMP 840 exposure (P < 0.01, Wilcoxon Rank Sum test).

CONCLUSION

The recommended dose of DMP 840 for further disease oriented evaluations is 40 mg/m2 administered over 24 hours every three weeks. The infusion duration evaluated in this study did not result in a substantial increase in the tolerable dose compared to shorter, less cumbersome schedules.

Cytotoxic synergy between pyrazoloacridine (NSC 366140) and cisplatin in vitro: inhibition of platinum-DNA adduct removal

Pyrazoloacridine (PA), an acridine congener that has shown selective toxicity in solid tumor cells, full activity against noncycling and hypoxic cells, and promising activity in a recent Phase I trial, is currently undergoing Phase II testing as a solid tumor-selective agent. In the present study, clonogenic assays were used to examine the cytotoxic effects when PA was combined with other antineoplastic agents in A549 human non-small cell lung cancer cells in vitro. Data were analyzed by the median effect method. Combinations of PA with antimetabolites (5-fluorouracil, methotrexate, and cytarabine) or with antimicrotubule agents (paclitaxel and vincristine) failed to exhibit synergy. Likewise, combinations of PA with alkylating agents (melphalan, 4-hydroperoxycyclophosphamide) were less than additive. In contrast, the combination of PA and cisplatin exhibited cytotoxicity that was additive or synergistic over a broad range of clinically achievable concentrations. Moreover, studies involving sequential exposure to PA and cisplatin revealed a synergistic interaction when cells were exposed to the two agents in either sequence. Synergy was likewise observed with this combination in T98G human glioblastoma cells and HCT8 human intestinal adenocarcinoma cells as well as AuxB1 hamster ovary cells. Flow microfluorimetry revealed that PA caused arrest of A549 cells in G1 and G2 phases of the cell cycle, providing a potential explanation for the antagonism between PA and antimetabolites or antimicrotubule agents. Further studies revealed that PA inhibited removal of platinum-DNA adducts in A549 cells in a dose-dependent fashion, with almost complete inhibition occurring at 1 microM PA. These latter observations provide a mechanistic explanation for the synergy between PA and cisplatin and suggest that this combination warrants further preclinical and clinical investigation.

Phase I and pharmacologic study of penclomedine, a novel alkylating agent, in patients with solid tumors

PURPOSE

To determine the maximum-tolerated dose (MTD), principal toxicities, and pharmacologic behavior of penclomedine, a novel alkylating agent.

PATIENTS AND METHODS

Penclomedine (45 to 550 mg/ m2/d every 3 weeks) was administered as a 1- or 3-hour intravenous (IV) infusion for 5 consecutive days to patients with solid tumors.

RESULTS

On a 1-hour dosing schedule, ataxia, vertigo, nystagmus, and a motor aphasia were the principal toxicities of penclomedine. These neurologic effects were dose-related, and evolved from complaints of somnolence and dizziness, to more pronounced signs and symptoms of cerebellar dysfunction. Up to and including doses of 415 mg/m2, these effects were well tolerated and resolved within 2 hours posttreatment. In contrast, both patients treated at the 550-mg/m2 dose level experienced a dose-limiting constellation of perinfusional aphasia and vertigo, with either ataxia of over 2 weeks' duration or recurrent dizziness. Prolongation of the infusion duration to 3 hours at this dose level resulted in less neurotoxicity; however, delayed trilineage hematologic toxicity precluded timely administration on this schedule. A statistically significant relationship was demonstrated between the development of ataxia and maximum plasma concentrations of penclomedine.

CONCLUSION

Neurotoxicity was the dose-limiting toxicity (DLT) of penclomedine administered as a 1-hour infusion daily for 5 days every 3 weeks, and the recommended dose for further evaluations was 415 mg/m2. The nature of the principal toxicities and the lack of any detectible antitumor activity indicate that phase II evaluations of penclomedine on this administration schedule should be focused on specific disease settings, such as breast cancer and intracerebral tumors, in which antitumor activity has been demonstrated.

Phase I and pharmacological study of CI-980, a novel synthetic antimicrotubule agent

CI-980 (NSC 613862) is one of a novel class of 1,2-dihydropyrido[3, 4-b]pyrazines that inhibits tubulin polymerization, presumably by binding to the colchicine binding site of tubulin. In a Phase I and pharmacological study, 16 patients with advanced solid neoplasms were treated with CI-980 on a continuous 72-h infusion schedule at doses ranging from 3.0-5.4 mg/m2/day every 3 weeks. High rates of central nervous system (CNS) toxicity and neutropenia occurred in both minimally and heavily pretreated patients who were treated with CI-980 doses above 3.75 mg/m2/day, which is the maximum tolerated dose and the recommended dose for additional evaluations. CNS effects, characterized by neurocortical, mood, and cerebellar manifestations, were generally observed toward the end of the infusion and immediately posttreatment and usually resolved within 48 h after the completion of treatment. Toxicity was mild to modest at the 3.75 mg/m2/day dose level. Neither clinical nor pharmacological risk factors that may predispose patients to the development of CNS effects were evident. Although no objective antineoplastic activity was observed in this Phase I study, CI-980 steady-state plasma concentrations achieved at the recommended dose of 3.75 mg/m2/day (mean +/- SE, 5.74 +/- 0.54 nM) approached and exceeded concentrations that have been associated with significant activity in preclinical studies, indicating that additional disease-directed evaluations of CI-980 may be warranted.

Pharmacokinetic, oral bioavailability, and safety study of fluorouracil in patients treated with 776C85, an inactivator of dihydropyrimidine dehydrogenase

PURPOSE

To study the absolute bioavailability and pharmacokinetics of an oral solution of fluorouracil (5-FU) in patients treated with 776C85, an oral inactivator of dihydropyrimidine dehydrogenase (DPD), and to evaluate the feasibility of administering oral 5-FU and 776C85 on a multiple-daily dosing schedule.

PATIENTS AND METHODS

Twelve patients with refractory solid tumors were enrolled onto this three-period study. In periods 1 and 2, patients were randomly assigned to treatment with 5-FU 10 mg/m2 on day 2 given by either the oral or intravenous (IV) route with oral 776C85 3.7 mg/m2/d on days 1 and 2. In period 3, patients received escalating doses of 5-FU (10 to 25 mg/ m2/d) orally for 5 days (days 2 to 6) with 776C85 3.7 mg/m2/d orally (days 1 to 7) every 4 weeks. Pharmaco-kinetic studies were performed in periods 1 and 2, and after the fifth oral dose of 5-FU in period 3.

RESULTS

Twelve patients completed the bioavailability and pharmacokinetic studies. Following oral 5-FU 10 mg/m2, the bioavailability was 122% +/- 40% (mean +/- SD), the terminal half-life (t1/2 beta) was 4.5 +/- 1.6 hours, the apparent volume of distribution (V beta) was 21.4 +/- 5.9 L/ m2, and the systemic clearance (Clsys) was 57.6 +/- 16.4 mL/min/m2. A correlation was observed between oral 5-FU systemic clearance and calculated creatinine clearance (r = .74; P = .009). Multiple-daily dosing did not appear to affect the pharmacokinetics of oral 5-FU. Neutropenia was the principal toxicity of oral 5-FU and 776C85, precluding escalation of oral 5-FU to doses greater than 25 mg/m2/d for 5 days every 4 weeks with 776C85.

CONCLUSION

The oral DPD inactivator 776C85 enables oral administration of 5-FU and may alter conventional 5-FU administration practices.

Phase I and pharmacologic study of topotecan in patients with impaired renal function

PURPOSE

To determine the toxicities, pharmacokinetics, and recommended doses of the topoisomerase I inhibitor, topotecan, in patients with varying degrees of renal excretory dysfunction.

PATIENTS AND METHODS

Fourteen patients with normal renal function [creatinine clearance (CrCl) > or = 60 mL/min] and 28 patients with varying degrees of renal dysfunction were treated with topotecan 0.4 to 2.0 mg/m2/d as a 30-minute infusion for 5 consecutive days every 3 weeks. Plasma and urine samples were obtained to determine the disposition of topotecan.

RESULTS

In patients with mild renal dysfunction (CrCl = 40 to 59 mL/min), dose-limiting hematologic toxicity was observed in three of eight patients receiving topotecan 1.0 mg/m2/d and in two of five patients receiving topotecan 1.5 mg/m2/d. In patients with moderate renal dysfunction (CrCl = 20 to 39 mL/min), dose-limiting hematologic toxicity was observed in three of eight patients who received topotecan 0.5 mg/m2/d, and in two of four patients receiving topotecan 1.0 mg/m2/d; these events were more frequently observed in extensively pretreated patients. Pharmacokinetic analyses showed significant correlations between CrCl and the plasma clearance of both total topotecan [Spearman's correlation coefficient (r2) = 0.65, P = .00001] and topotecan lactone (r2 = 0.65, P = .00003). Mean systemic plasma clearance of total topotecan was significantly reduced in patients with mild (P = .04) and moderate (P = .00006) renal dysfunction. There was no evidence of changes in the pharmacodynamic relationship between topotecan exposure (AUC) and myelotoxicity.

CONCLUSION

Dose adjustments are required in patients with moderate, but not mild, renal impairment. For patients with moderate renal dysfunction, the recommended starting dose of topotecan is 0.75 mg/m2/d for 5 days every 3 weeks. Moreover, extensively pretreated patients need further dose reductions.

A phase I and pharmacological study of topotecan infused over 30 minutes for five days in patients with refractory acute leukemia

The principal objectives of this study were to determine the feasibility of escalating doses of the hydrophilic topoisomerase I (topo I) inhibitor topotecan (TPT) as a 30-min infusion daily for 5 days in adults with refractory or relapsed acute leukemia and to study the pharmacokinetic behavior of high doses of TPT and pharmacodynamic determinants of TPT activity. Fourteen patients received 27 courses of TPT at doses ranging from 3.5 to 5.75 mg/m2/day every 3 weeks. A constellation of unusual adverse effects, consisting of high fever, rigors, precipitous anemia, and hyperbilirubinemia, was the principal dose-limiting toxicity of high doses of TPT on this schedule. These toxicities were consistently intolerable at the 5.75 mg/m2/day dose level; however, they were neither severe nor common at lower doses. Although the precise etiology of these effects is not known, high doses of TPT may induce acute hemolytic reactions in this patient population. Severe, albeit transient, mucositis was experienced by two of eight patients in 2 of 17 courses at the next lower dose level, 4.5 mg/m2/day, which was determined to be the maximum tolerated dose and the dose recommended for further trials. The pharmacokinetic behavior of TPT at high doses was not dose dependent and resembled that at lower doses. In view of preclinical data suggesting that TPT sensitivity might correlate with topo I levels, topo I content in leukemia blasts was assessed by Western blotting. Variations in topo I content were observed. Moreover, strong correlations were evident between topo I content and two markers of proliferation, proliferating cell nuclear antigen and nuclear protein B23, raising the possibility that differences in topo I content observed among various leukemia specimens might reflect differences in the proliferating fractions of cells in various leukemia samples. Although complete clearance of circulating leukemia blasts occurred in most courses, neither sustained responses nor hematopoietic recovery were observed in the heavily pretreated, poor-risk patients enrolled in this study, and it was not possible to correlate these differences in topo I content with clinical response. These results indicate that substantial dose escalation of TPT as a 30-minute infusion for a 5-day schedule above myelosuppressive doses is feasible in adults with refractory or relapsed leukemias; however, further development of alternate high-dose schedules in leukemia may be warranted in view of the nature of the dose-limiting toxicity and the lack of sustained clinical responses in this preliminary investigation.

Sequences of topotecan and cisplatin: phase I, pharmacologic, and in vitro studies to examine sequence dependence

PURPOSE

A phase I and pharmacologic study was performed to evaluate the feasibility of administering the topoisomerase I (topo I) inhibitor topotecan (TPT) in combination with cisplatin (CDDP) in minimally pretreated adults with solid tumors. The study was designed to evaluate the magnitude of the toxicologic and pharmacologic differences between the two sequences of drug administration.

MATERIALS AND METHODS

TPT was administered as a 30-minute infusion daily for 5 days and CDDP was given either before TPT on day 1 or after TPT on day 5. Each patient was treated with both schedules on an alternating basis every 3 weeks. Sequential dose escalation of TPT or CDDP resulted in three dosage permutation of TPT/CDDP (mg/m2): 0.75/50, 1/50, and 0.75/75. After the maximum-tolerated dose (MTD) level was achieved, the feasibility of using granulocyte colony-stimulating factor (G-CSF) to permit further dose escalation was studied. To examine the interaction of TPT and CDDP in vitro, human A549 lung cancer cells were exposed to these agents concurrently and sequentially.

RESULTS

Dose-limiting neutropenia and thrombocytopenia resulted after the doses of TPT or CDDP were increased to greater than 0.75 and 50 mg/m2, respectively, without and with G-CSF. The sequence of CDDP before TPT induced significantly worse neutropenia and thrombocytopenia than the alternate sequence. In vitro studies failed to provide any evidence for the differences in the cytotoxicity of these two sequences. Instead, pharmacokinetic studies suggested that the differences in toxicity were due, in part, to lower TPT clearance and exposure when CDDP preceeds TPT, possibly due to subclinical renal tubular toxicity induced by CDDP.

CONCLUSION

The sequence of CDDP before TPT at doses of 50 and 0.75 mg/m2, respectively, is recommended for subsequent clinical trials in tumor types in which both agents have significant single-agent activity. The potential for sequence-dependent cytotoxic, toxicologic, and pharmacologic effects should be evaluated in concurrent clinical and laboratory studies in the course of developing combination chemotherapy regimens that consist of topo I-targeting agents and other antineoplastic agents, particularly DNA-damaging agents.

The effects of food and divided dosing on the bioavailability of oral vinorelbine

The effects of food and divided dosing on the bioavailability of a liquid-filled gelatin capsule formulation of vinorelbine (Navelbine), a semisynthetic vinca alkaloid with broad clinical activity, was evaluated in patients with advanced solid tumors. A group of 13 patients were randomized to treatment with the oral formulation at the recommended phase II dose of 80 mg/m2 per week either in the fasting state or after ingestion of a standard meal. Patients were treated 1 week later in the alternate state relative to their first dose. The effects of divided dosing were assessed during the 3rd week, at which time vinorelbine was administered in two divided doses. After the completion of pharmacokinetic and bioavailability studies, patients received the oral formulation at a dose of 80 mg/m2 per week in two divided doses to evaluate the feasibility of chronic oral drug administration. Both manipulations resulted in small, albeit statistically significant, reductions in the relative bioavailability of this oral formulation. The relative bioavailability decreased by 22 +/- 28% when treatment followed the ingestion of a standard meal, possibly due to a delay in gastrointestinal transit time. The mean time of maximum plasma concentration (Tmax) increased from 1.3 +/- 1.6 h in the fasting state to 2.5 +/- 1.6 h in the fed state, although this difference was not statistically significant. Similarly, the relative bioavailability declined by 16 +/- 51% when vinorelbine was administered in two divided doses. An analysis of dose proportionality revealed disproportionate increases in dose-normalized Cmax and AUC values with single oral doses above 120 mg, which may account for this phenomenon. The high clearance of vinorelbine, which approaches hepatic blood flow, and the lack of dose proportionality after oral administration, indicate that there is a large first-pass effect which may be saturable, or nonlinear, above single doses of 120 mg. In addition, the toxicological and pharmacological characteristics of oral vinorelbine indicate that treatment after a standard meal or on a divided dosing schedule is safe. Chronic oral administration of the agent in two divided doses was also well tolerated. However, the small reduction in the relative bioavailability following the ingestion of a standard meal and with divided dosing suggest the need for further pharmacodynamic studies to determine if reductions in drug exposure of this magnitude may portend diminished antitumor activity.

Development of a canine chemotherapeutic model with ifosfamide

The purpose of this study was to develop a canine experimental model for neoadjuvant chemotherapy of primary bone tumors with ifosfamide, which is safe and clinically relevant for use in human beings with bone tumors. Our study was divided into two steps, each with four dogs. In the first step ifosfamide was administered for 4 consecutive days in three cycles with 3-week intervals between each cycle. For this first step a daily dosage of 300 mg/m2 of body surface resulted in only moderate leukopenia, whereas a daily dosage of 450 mg/m2 caused severe leukopenia. Therefore, to determine the maximal dose tolerable and to verify the results from step 1, we administered the higher daily dosage of 450 mg/m2 in step 2 for four successive cycles with 3-week intervals. In each step one dog died acutely after the first cycle of chemotherapy. In addition during step 2 one dog died of overwhelming sepsis after the second cycle of ifosfamide. The remaining five dogs survived without other appreciable laboratory abnormalities. Neither hematuria nor proteinuria was observed throughout the course of study, and relevant findings were not observed at autopsy. We determined that 450 mg/m2 was the maximal tolerated dosage of ifosfamide for our regimen, with the dose-limiting factor being myelosuppression, specifically leukopenia. Using this canine model, we can estimate the effect of ifosfamide on bone graft incorporations and the fixation of biologic prostheses that is clinically the most important aspect of limb salvage surgery.

Phase I and pharmacologic studies of topotecan in patients with impaired hepatic function

BACKGROUND

Topotecan, a topoisomerase I inhibitor that has demonstrated anticancer activity toward leukemias and solid tumors in clinical trials, is eliminated via hepatic and renal routes. However, dosing guidelines for the administration of topotecan to patients with impaired hepatic function have not yet been established.

PURPOSE

We compared the maximum tolerated doses (MTDs), the toxic effects, and the pharmacokinetics and pharmacodynamics of topotecan in patients who had refractory, malignant, solid tumors and who either had or lacked hepatic injury. The potential role of three substrate markers of liver function (indocyanin green [ICG]-- a marker of hepatic blood flow; lorazepam--a substrate marker of hepatic glucuronidation; and antipyrine--a substrate marker for cytochrome P450 activity) in optimizing topotecan doses for patients with liver injury was also evaluated.

METHODS

Twenty-one cancer patients, 14 of whom had hepatic injury due to metastatic disease, biliary obstruction, or cirrhosis, were treated with intravenously delivered courses of topotecan consisting of 0.5, 1.0, or 1.5 mg/m2 of drug per day for 5 days. Most patients received more than one course of treatment, with new courses initiated at 3-week intervals. Patient responses (evaluated by tumor measurements) and treatment-induced toxic effects were assessed. Prior to the initiation of topotecan treatment, patients were given intravenous injections of ICG, lorazepam, and antipyrine to determine the plasma pharmacokinetics of these compounds. The pharmacokinetics of topotecan (both the lactone and the carboxylate forms) were determined by analysis of plasma and urine samples collected on the first day of the first course of drug treatment. Scatter plots of area under the plasma concentration versus time curves in relation to percent decreases in either absolute neutrophil count or platelet count were used to explore the pharmacodynamics of topotecan. The Student's t test and the Mann-Whitney U test were used to compare pharmacokinetic parameters between patients with and without abnormal hepatic function. Correlations were assessed using the Spearman's rank correlation coefficient (rs). Reported P values are based on two-tailed tests of significance.

RESULTS

Patients with hepatic injury tolerated topotecan doses up to 1.5 mg/m2, i.e., the MTD of this drug established in previous studies. The nature and severity of treatment-induced toxic effects and the pharmacokinetics of topotecan were similar in patients with and without liver injury. No differences were observed in the urinary excretion of topotecan between the two patient groups. Clearances of total topotecan and its lactone species correlated only with clearance of ICG (rs = .64, P = .004; and rs = .68, P = .0017, respectively). The pharmacodynamic effects of topotecan were not altered by liver dysfunction.

CONCLUSIONS AND IMPLICATIONS

Cancer patients with hepatic injury can be treated with topotecan at a starting dose of 1.5 mg/m2, given daily for 5 days and administered every 3 weeks. Topotecan dose modifications do not appear to be required for patients with hepatic dysfunction and normal renal function.

Cytotoxic effects of topotecan combined with various anticancer agents in human cancer cell lines

BACKGROUND

Topotecan (TPT) is a topoisomerase I poison that exhibits antineoplastic activity. Analysis of the cytotoxic effects of combinations of TPT and other anticancer agents has been limited.

PURPOSE

We assessed the cytotoxic effects produced by combinations of TPT and other antineoplastic agents in experiments involving multiple human cancer cell lines of diverse histologic origins.

METHODS

The cytotoxic effects of various antimetabolites (fluorouracil, methotrexate, or cytarabine), antimicrotubule agents (vincristine or paclitaxel [Taxol]), DNA alkylating agents (melphalan, bis[chloroethyl]nitrosourea [BCNU], or 4-hydroperoxycyclophosphamide [4HC]), and a DNA-platinating agent (cisplatin), alone and in combination with TPT, were measured in clonogenic (i.e., colony-forming) assays. HCT8 ileocecal adenocarcinoma, A549 non-small-cell lung carcinoma, NCI-H82ras(H) lung cancer, T98G glioblastoma, and MCF-7 breast cancer cell lines were used in these assays. The data were analyzed by the median effect method, primarily under the assumption that drug mechanisms of action were mutually nonexclusive (i.e., completely independent of one another). For each level of cytotoxicity (ranging from 5% to 95%), a drug combination index (CI) was calculated. A CI less than 1 indicated synergy (i.e., the effect of the combination was greater than that expected from the additive effects of the component agents), a CI equal to 1 indicated additivity, and a CI greater than 1 indicated antagonism (the effect of the combination was less than that expected from the additive effects of the component agents).

RESULTS

When the mechanisms of drug action were assumed to be mutually nonexclusive, virtually all CIs for combinations of TPT and either antimetabolites or antimicrotubule agents revealed cytotoxic effects that were less than additive. The CIs calculated at low-to-intermediate levels of cytotoxicity for combinations of TPT and the DNA alkylating agents melphalan, BCNU, and 4HC also showed drug effects that were less than additive; in most cases, however, nearly additive or even synergistic effects were observed with these same drug combinations at high levels of cytotoxicity (i.e., at > or = 90% inhibition of colony formation). Results obtained with combinations of TPT and cisplatin varied according to the cell line examined. With A549 cells, less than additive effects were seen at low-to-intermediate levels of cytotoxicity, and more than additive effects were seen at high levels of cytotoxicity. With NCI-H82ras(H) cells, synergy was observed over most of the cytotoxicity range.

CONCLUSIONS AND IMPLICATIONS

TPT cytotoxicity appears to be enhanced more by combination with certain DNA-damaging agents than by combination with antimetabolites or antimicrotubule agents. Interactions between TPT and other drugs can vary depending on the cell type examined. Further investigation is required to determine the basis of the observed effects and to determine whether these in vitro findings are predictive of results obtained in vivo.

A phase II trial of topotecan in patients with previously untreated pancreatic cancer

Because currently available chemotherapeutic agents are largely ineffective in the treatment of pancreatic cancer, novel treatments are urgently needed to improve outcomes in this disease. The purpose of this phase II study was to evaluate the anti-tumor activity of topotecan, a hydrophilic camptothecin analog that has demonstrated a wide range of anti-tumor activity in preclinical and phase I studies. Topotecan was administered as a 30 min infusion at a dose of 1.5 mg/m2/day for five consecutive days every 3 weeks, to chemotherapy-naive patients with advanced pancreatic cancer. Neutropenia was the principal toxicity of topotecan on this dosing schedule. No significant anti-tumor responses were observed in 27 patients with measurable disease. The median time to disease progression was 7 weeks and the median survival duration was 17.5 weeks. Thus, topotecan, administered on this schedule, is ineffective for patients with pancreatic carcinoma.