Multicenter phase II study of trabectedin in patients with metastatic castration-resistant prostate cancer.

BACKGROUND: This multicenter phase II trial evaluated the efficacy and safety of trabectedin in metastatic castration-resistant prostate cancer (CRPC). PATIENTS AND METHODS: Two schedules were evaluated in three cohorts: weekly as 3-h i.v. infusion at 0.58 mg/m(2) for 3 out of 4 weeks (Cohort A, n = 33), and every 3 weeks (q3wk) as 24-h infusion at 1.5 mg/m(2) (Cohort B1, n = 5) and 1.2 mg/m(2) (Cohort B2, n = 20). The primary end point was prostate-specific antigen (PSA) response; secondary end points included safety, tolerability and time to progression (TTP). RESULTS: Trabectedin resulted in PSA declines ≥ 50% in 12.5% (Cohort A) and 10.5% (Cohort B2) of patients. Among men pretreated with taxane-based chemotherapy, PSA response was 13.6% (Cohort A) and 15.4% (Cohort B2). PSA responses lasted 4.1-8.6 months, and median TTP was 1.5 months (Cohort A) and 1.9 months (Cohort B2). The dose of 1.5 mg/m(2) (approved for soft tissue sarcoma) given as 24-h infusion q3wk was not tolerable in these patients. At 1.2 mg/m(2) q3wk and 0.58 mg/m(2) weekly, the most common adverse events were nausea, fatigue and transient neutropenia and transaminase increase. CONCLUSIONS: Two different trabectedin schedules showed modest activity in metastatic CRPC. Further studies may require identification of predictive factors of response in prostate cancer.

P-glycoprotein binding and modulation of the multidrug-resistant phenotype by estramustine.

BACKGROUND: Previous preclinical studies of combinations of estramustine and vinblastine or paclitaxel (Taxol) have shown that it is possible to achieve a greater than additive cytotoxicity with these antimicrotubule drug combinations. Phase II studies in hormone-refractory prostate cancer have demonstrated clinical antitumor activity of sufficient magnitude to stimulate further laboratory and clinical studies of these drugs combinations. PURPOSE: Our purpose was to characterize the interactions of estramustine with P-glycoprotein and to determine its effects. METHODS: Standard laboratory techniques were used to study the effects of estramustine on intracellular drug concentrations, cytotoxicity, and induction of messenger RNA (mRNA) for the MDR1 (also known as PGY1) gene. Using a photoaffinity analogue of estramustine 17-0-[[2-[3-(4-azido-3-[125I]-iodophenyl) propionamido]ethyl]-carbamyl]estradiol-3-N-bis(2-chloroethyl)ca rba mate ([125I]AIPP-estramustine), binding to the membrane proteins of human ovarian (SKOV3) and their multidrug-resistant counterpart SKVLB1 cells was studied. Southern-blot analysis was performed on DNA extracted from human prostate carcinoma wild-type DU145, estramustine-resistant cell line (E4), and SKVLB1 cells. RESULTS: Membrane fractions from SKOV3 and SKVLB1 cells were analyzed for proteins that could be photoaffinity labeled with [125I]AIPP-estramustine. Competitive inhibition of this binding was achieved with excess concentrations of (in order of efficacy) estramustine, vinblastine, verapamil, progesterone, and to a lesser degree, by paclitaxel but not with estramustine phosphate, estradiol, and estriol. SKVLB1 cells accumulated much less [3H]vinblastine and [3H]paclitaxel than did SKOV3 cells. Estramustine caused a concentration-dependent enhancement of drug accumulation in the SKVLB1 cells to a maximum of approximately 12-fold. No effect of estramustine was apparent for the wild-type SKOV3 cells. In comparison with verapamil, estramustine was less effective as a modulator; however estramustine demonstrated good chemosensitizing activity in combination with actinomycin D and vinblastine. Neither short-term, low-dose no longer-term, higher concentration were found to produce measurable transcript (mRNA for the MDR1 gene levels. Such data suggest that, at least levels. Such data suggest that, at least for two distinct human cell line (SKOV3 and DU145), estramustine does not induce the overexpression of the MDR1 gene. CONCLUSION: It is apparent from the P-glycoprotein data that estramustine interacts with this efflux pump, altering intracellular drug accumulation. Overall, the nonempiric basis for including estramustine in clinical protocols that contain other multidrug-resistant drugs is strengthened by the present data.

Phase I trial of fluorouracil modulation by N-phosphonacetyl-L-aspartate and 6-methylmercaptopurine riboside: optimization of 6-methylmercaptopurine riboside dose and schedule through biochemical analysis of sequential tumor biopsy specimens.

Preclinical and clinical studies demonstrate that the selective antitumor activity of fluorouracil (5-FU) is enhanced by agents which perturb certain intracellular nucleotide pools. We previously demonstrated that the combination of N-phosphonacetyl-L-aspartate (PALA), which depletes pyrimidine nucleotide pools, and 5-FU yielded a 43% response rate among 37 assessable patients with colorectal carcinoma. In preclinical tumor models, 6-methylmercaptopurine riboside (MMPR), an inhibitor of purine synthesis, elevates phosphoribosylpyrophosphate (PRPP) pools and promotes the anabolism of 5-FU to fluorinated nucleotides. In vivo, the addition of MMPR enhances the therapeutic efficacy of PALA-5-FU. In a phase I trial, we sought to determine the optimal dose and schedule of MMPR in combination with PALA (250 mg/m2 on day 1) and 5-FU (1300 mg/m2 by 24-hour infusion on day 2). MMPR (75-225 mg/m2) was given intravenously on day 1 to 27 patients with solid tumors (15 colorectal, seven breast, five other). Toxic effects were mild to moderate and included leukopenia, mucositis, nausea, or rash. Two of seven patients given MMPR at 225 mg/m2 had grade 3 diarrhea. PRPP was measured using a [14C]orotic acid 14CO2 release assay in tumor biopsy specimens obtained before and 12 hours and 24 hours after MMPR doses were given to 20 patients. The addition of MMPR elevated PRPP pools in human solid tumors. At 12 hours after treatment, two (50%) of four patients showed a twofold or greater elevation of PRPP at the MMPR dose level of 75 mg/m2; a similar elevation was observed in five (71%) of seven patients given 150 mg/m2 MMPR and in three (43%) of seven patients given 225 mg/m2 MMPR. At 24 hours after treatment, results for the respective dose levels of MMPR were two (33%) of six patients, one (20%) of five patients, and four (57%) of seven patients. Administration of the two highest MMPR dose levels appeared to result in a greater increase in tumor PRPP levels. However, toxicity was greater at the 225 mg/m2 dose level; therefore, the 150 mg/m2 dose level was favored. Tumor levels of PRPP decreased between 12 hours and 24 hours in nine (56%) of 16 patients. This time course indicates that MMPR should be administered at the beginning of the 24-hour infusion of 5-FU.

Increase of beta(III)- and beta(IVa)-tubulin isotopes in human prostate carcinoma cells as a result of estramustine resistance.

Estramustine (EM), an antimicrotubule agent, is effective against hormone-refractory prostate cancer when used in combination with vinblastine or paclitaxel. To understand the effect of EM on beta-tubulin, a cellular target for this class of drugs, human prostate carcinoma cells (DU-145) were made resistant to EM, and two cell lines were selected at 12- (EM-12) and 15-microMolar (EM-15) concentrations of the drug. These cell lines exhibited 8- to 9-fold resistance to EM and 2- to 4-fold cross-resistance to paclitaxel. Immunofluorescent staining of the cells with beta-tubulin isotype-specific antibodies showed an approximately 6-fold increase in the beta(III)-tubulin levels and moderate increase in overall beta-tubulin levels in EM-resistant cells when compared to DU-145 cells. This increase of beta(III) isotype was confirmed by Western analysis. A reverse transcriptase-PCR assay was also employed using beta-tubulin isotype-specific primers to quantify beta-tubulin isotype RNA. A 4-fold increase in beta(III) and a 3-fold increase in beta(IV alpha) transcript were seen in both EM-resistant cell lines. These results indicate that overexpression of specific beta-tubulin isotypes may play a role in the cellular defense against EM and other antimicrotubule agents.

Phase I/pharmacokinetic study of topotecan by 24-hour continuous infusion weekly.

Topotecan (SK&F 104864, hycamptamine, NSC 609699) is believed to exert its cytotoxic effects through inhibition of topoisomerase I, the activity of which recovers rapidly on removal of the drug in vitro. In vivo studies show that the activity of topotecan is schedule dependent, favoring repeated doses. Early human studies showed that topotecan (the active lactone) had a short half-life in plasma. To prolong drug exposure, we administered topotecan as a 24-h i.v. infusion and repeated it weekly. We treated 32 patients with doses of 1.0-2.0 mg/m2. Median performance status was 1, and all but four patients had received prior chemotherapy. Dose-limiting neutropenia occurred at doses > or = 1.75 mg/m2; nadirs were observed after 1-3 doses. The recommended phase II dose is 1.5 mg/m2/week. One patient with metastatic colon cancer had a partial response. Both plasma topotecan (lactone) and total topotecan (measured by converting the hydroxyacid form to the lactone by acidification of the sample) were measured by high-performance liquid chromatography in 21 patients. During infusion, mean topotecan plasma steady-state concentrations ranged from 4.7-11.4 nM. Plasma elimination was best fit to a one-compartment model with a mean t1/2 of 3.5 h. The mean total body clearance was 388 ml/min/m2. Concentrations of the inactive form approximated those of the lactone throughout. No evidence for dose-dependent pharmacokinetics was observed in this dose range. Pharmacodynamic analysis, using the sigmoid Emax model, revealed that the pharmacokinetic parameters of both lactone and total drug were positively correlated with bone marrow toxicity. Total drug steady-state plasma concentration provided a good estimate of neutropenia, suggesting a simple, easily monitored, pharmacokinetic parameter for adaptive dosing using this schedule. Phase II evaluation of this weekly schedule is indicated in solid tumors.

Pharmacokinetic study of trimetrexate in combination with cisplatin.

The addition of the antifol methotrexate to cisplatin (DDP) produces supraadditive antitumor effects in preclinical studies, but in the clinic this combination of two nephrotoxic drugs is limited by excessive toxicity. Trimetrexate (TMTX) is a second generation antifol with predominantly nonrenal elimination and antitumor activity superior to that of methotrexate in preclinical models. In early clinical trials TMTX demonstrated promising activity in non-small cell lung cancer, and nephrotoxicity was rare. We performed a Phase I clinical and pharmacological study of TMTX (escalating doses) in combination with DDP (20 mg/m2), both administered i.v. for 5 consecutive days, every 4 wk. The pharmacokinetics of TMTX was determined in 15 patients after administration of the single agent (baseline study) and following the Day 1 and Day 5 doses in the TMTX-DDP combination. The recommended Phase II single-agent dose of TMTX on this schedule, 8 mg/m2, did not produce excessive toxicity when given concurrently with DDP. Significant drug-related nephrotoxicity was not observed, even in patients receiving multiple courses of TMTX-DDP. The mean renal clearance of TMTX increased 1.4-fold and 2.8-fold over baseline on Days 1 and 5, respectively, of TMTX-DDP. Urinary flow was similarly greater on days of TMTX-DDP treatment. The nonrenal clearance of TMTX was unaffected by concurrent DDP. The steady-state volume of distribution, Vdss, and terminal elimination half-life were significantly greater on Day 5 of TMTX-DDP compared to baseline. The plasma protein-binding of TMTX in vitro was not altered by DDP, and the disappearance of ultrafilterable DDP from normal plasma in vitro was unchanged by TMTX. Although a protein-binding interaction of TMTX and DDP was not detected in normal plasma in vitro, the changes in renal clearance, Vdss, and the terminal half-life were consistent with a greater fraction of unbound TMTX in plasma following Day 5 of TMTX-DDP. Effects of DDP on the binding of TMTX to extravascular tissue components, or on the renal handling of TMTX, cannot be excluded. The increase in TMTX renal clearance correlated with increased urinary flow, which may improve the therapeutic index of TMTX as both an antineoplastic and antiparasitic agent.

Phase I and pharmacokinetic study of the novel platinum analogue CI-973 on a 5-daily dose schedule.

CI-973, a platinum(II) derivative with a 2-methyl-1,4-butanediamine carrier ligand, has activity in cisplatin-resistant tumor models in vitro and in vivo. In a Phase I pharmacokinetic study, 31 patients were treated with CI-973 (24 to 50 mg/m2/day for 5 days; 28-day cycles) given i.v. over 30 min without routine antiemetic prophylaxis or hydration. Of the 29 patients evaluable for maximum tolerated dose determination, most had a performance status of 0 or 1, and most had received prior chemotherapy. Neutropenia was dose limiting at 40 and 50 mg/m2/day. Recovery from neutropenia was generally rapid with nadir counts and recovery usually occurring by Days 15 and 22, respectively. Drug-associated thrombocytopenia was uncommon and never severe, even in patients with Grade 4 neutropenia. Anemia was common, but did not appear dose related. Drug-related nausea and vomiting and changes in renal function were relatively infrequent and mild. No clinically evident ototoxicity was reported, although changes in audiograms were noted in several patients. CI-973 concentrations were measured in plasma ultrafiltrate and urine by high-pressure liquid chromatography. The harmonic mean terminal half-life was 2.0 h. The mean CI-973 renal and nonrenal clearance values were 42.3 and 37.4 ml/min/m2, respectively. The mean recovery of CI-973 in urine was 53% of the administered dose. The mean ratio of CI-973 renal clearance to creatinine clearance was 0.92. Total clearance correlated with creatinine clearance (r2 = 0.63). A relationship between toxicity, expressed as the percentage of reduction in absolute granulocyte count, and area under the CI-973 plasma concentration-time curve was found in a subgroup of "good-risk" patients. This relationship, described well by a sigmoidal Emax pharmacodynamic model, did not hold for patients with extensive prior therapy or poor performance status. A model for toxicity prediction based on dose and creatinine clearance has been derived and will be validated in future studies. The recommended Phase II dose of CI-973 is 30 mg/m2/day for 5 days.

Cloning and sequencing of human betaIII-tubulin cDNA: induction of betaIII isotype in human prostate carcinoma cells by acute exposure to antimicrotubule agents.

Antimicrotubule drugs are used as chemotherapeutic agents due to their effects on essential cellular functions such as mitosis, organelle transport and maintenance of cell shape. When used in combination, paclitaxel with estramustine or vinblastine has demonstrated activity against hormone refractory prostate cancer. To understand the mechanism of resistance that develops in patients as a result of antimicrotubule drug therapy, we exposed human prostate carcinoma cells to IC20 and IC40 doses of estramustine, paclitaxel or vinblastine for 48 h and examined the beta-tubulin (the cellular target) isotype composition. The results revealed an increase in the betaIII-tubulin isotype as a result of drug treatment both at protein and message levels. In addition, examination of human brain cell lines with different intrinsic levels of betaIII showed that cell lines with higher betaIII levels were more resistant to paclitaxel. These results are in agreement with our previous findings in human prostate carcinoma cell lines that were made resistant to estramustine or paclitaxel and suggest an important function for betaIII in antimicrotubule drug resistance. Also, the complete coding sequence of human betaIII tubulin reported here will provide molecular tools for future investigations.

Phase I trial of thiotepa in combination with recombinant human granulocyte-macrophage colony-stimulating factor.

PURPOSE: The ability of growth factors to stimulate marrow recovery suggests their potential for use in dose intensification of cytotoxic drugs. We performed a phase I study of the alkylating agent thiotepa in combination with granulocyte-macrophage colony-stimulating factor (GM-CSF), with the goal of dose-escalation of thiotepa. Thiotepa was selected based on its capacity for dose escalation to more than 1 g/m2 in the marrow transplantation setting. PATIENTS AND METHODS: The starting dose of thiotepa (75 mg/m2) was the highest dose evaluated in our previous phase I trial. Thirteen patients received 22 courses of thiotepa and GM-CSF. The dose of GM-CSF was 10 micrograms/kg subcutaneously daily in six patients and 5 micrograms/kg in seven patients. RESULTS: Three patients (23%) developed grade 3 to 4 neutropenia on the first course, with a recovery to more than 1000/mm3 in 4.7 days (mean). Recovery was as rapid with the 5 micrograms/kg as it was with the 10 micrograms/kg GM-CSF dose. Thrombocytopenia grade 3 to 4 affected seven of 13 (54%) patients in the first course; counts recovered to more than 50,000/mm3 in a median of 15 days. GM-CSF at either dose did not influence markedly the severity or duration of thrombocytopenia, and did not permit dose escalation of thiotepa. Among the seven patients who received a second cycle of treatment, six of seven experienced grade 3 or 4 thrombocytopenia that lasted a median of 15.5 days. Five had thrombocytopenia that lasted more than 35 days after one to three cycles of treatment. Plasma concentrations of thiotepa and tepa were measured by gas chromatography in eight patients. The plasma elimination of thiotepa fit a two-compartment open model with a harmonic mean terminal half-life of 2.44 hours. The mean total body clearance was 217.9 mL/min/m2, and the mean steady-state volume of distribution (Vdss) was 36.8 L/m2. The half-life of tepa was 7.98 hours, and the ratio of the area under the plasma concentration versus time curve (AUC) of tepa to that of thiotepa was 0.79. CONCLUSIONS: These data were consistent with our previous observations at this dose, and indicated that the severity of toxicity in these patients was not explained by aberrant pharmacokinetic indices. We conclude that, independent of effects on neutropenia, severe and cumulative platelet toxicity precludes further escalation of thiotepa dose despite the use of GM-CSF.

Phase II study of estramustine and vinblastine, two microtubule inhibitors, in hormone-refractory prostate cancer.

PURPOSE: Estramustine phosphate (EMP) and vinblastine are two microtubule inhibitors with distinct molecular targets and at least additive antimicrotubule effects in vitro. Their modest single-agent activities in hormone-refractory prostate cancer, nonoverlapping toxicities, and lack of cross-resistance prompted a phase II trial in hormone-refractory prostate cancer. PATIENTS AND METHODS: Thirty-six assessable patients at the Fox Chase Cancer Center and seven Fox Chase Cancer Center Network institutions were treated with oral EMP 600 mg/m2 on days 1 to 42 and vinblastine 4 mg/m2 intravenously (IV) once a week for 6 weeks. Courses were repeated every 8 weeks. Response assessment was based on a change in serum prostate-specific antigen (PSA) levels and was correlated with change in pain scores. RESULTS: PSA decreased from baseline by at least 50% in 22 patients (61.1%) and by > or = 75% in eight patients (22.2%). A 50% or more decrease in PSA on three successive 2-week measurements together with an improved or stable pain score, performance status, and measurable soft tissue disease (if present) was required for a partial response (PR), which occurred in 11 patients for an overall response rate of 30.5% (95% confidence interval, 15.6% to 45.6%). In seven patients with measurable nonosseous disease, there was one PR (14%) and one minor response (MR). In 28 patients with assessable pain, major pain responses occurred in 12 (42.9%). PSA response (> or = 50% decrease times three measurements) was predictive of major pain response with a 93.7% specificity, a 50% sensitivity, and a positive predictive value of 85.7%. CONCLUSION: We conclude that EMP and vinblastine is an active combination in hormone-refractory prostate cancer.

Phase II trial of 96-hour paclitaxel plus oral estramustine phosphate in metastatic hormone-refractory prostate cancer.

PURPOSE: To evaluate the antitumor activity of 96-hour paclitaxel and daily oral estramustine phosphate (EMP) in patients with metastatic hormone-refractory prostate cancer (HRPC). PATIENTS AND METHODS: Thirty-four patients with adenocarcinoma of the prostate that progressed after one or more hormonal therapies and a trial of antiandrogen withdrawal were enrolled onto this phase II trial. Patients received paclitaxel 120 mg/m2 by 96-hour intravenous (i.v.) infusion on days 1 through 4 of each 21-day cycle, together with daily oral EMP 600 mg/m2/d, continuously. RESULTS: Four of nine patients with measurable disease had objective responses (one complete response [CR] and three partial responses [PRs]) in liver (two patients) or nodes (two patients) of 2, 6, 8, and 20 months' duration. Of 25 assessable patients with metastases limited to bone, 14 had a > or = 50% decline in pretreatment prostate-specific antigen (PSA) level sustained for at least 6 weeks and seven had a > or = 80% decline. Overall, 17 of 32 patients (53.1%) with elevated pretreatment PSA levels had a > or = 50% decline of PSA and nine (28.1%) had a > or = 80% decrease. The main toxicities (> or = grade 2) were nausea, fluid retention, and fatigue, which occurred in 33%, 33%, and 24.2% of patients. Median time to progression, based on increasing PSA level and other clinical criteria, was 22.5 weeks. The estimated median overall survival time is 69 weeks. CONCLUSION: The combination of EMP and 96-hour paclitaxel is an active regimen for patients with HRPC. These results further support the therapeutic strategy of combining agents that impair microtubule function by complementary mechanisms.

Significant activity of paclitaxel in advanced transitional-cell carcinoma of the urothelium: a phase II trial of the Eastern Cooperative Oncology Group.

PURPOSE: To assess the efficacy and toxicity of single-agent paclitaxel as first-line chemotherapy in patients with locally advanced or metastatic transitional-cell carcinoma of the urothelium. PATIENTS AND METHODS: Twenty-six eligible patients were enrolled onto this cooperative group study and treated with paclitaxel at a dosage of 250 mg/m2 by 24-hour continuous infusion every 21 days until progression or patient intolerance. All patients received recombinant human granulocyte colony-stimulating factor (rhG-CSF) at 5 micrograms/kg/d for at least 10 days during each cycle. RESULTS: Eleven of 26 patients (42%; 95% confidence interval [CI], 23% to 63%) demonstrated an objective response, with seven achieving a complete clinical response (CR) (27%; 95% CI, 12% to 48%) and four (15%) a partial response (PR). The median duration of response in the 11 responders is 7+ months (range, 4 to 17), with five responders (four CRs, one PR) remaining progression-free at 5, 6, 10, 12, and 16 months from the start of therapy. The estimated median survival duration for all patients is 8.4 months. Hematologic toxicity consisted of anemia (12% grade 3) and granulocytopenia (4% grade 3, 19% grade 4), with two patients developing granulocytopenic fevers. Nonhematologic toxicity included grade 3 mucositis in 11%, grade 3 neuropathy in 11%, and grade 4 diarrhea in 4%. CONCLUSION: Single-agent paclitaxel at this dosage and schedule is one of the most active single agents in previously untreated patients with advanced urothelial carcinoma, and is well tolerated by this patient population when given with hematopoetic growth factor support.

Phase I pharmacokinetic trial of perillyl alcohol (NSC 641066) in patients with refractory solid malignancies.

Perillyl alcohol (POH) is a monoterpene with anticarcinogenic and antitumor activity in murine tumor models. Putative mechanisms of action include activation of the transforming growth factor beta pathway and/or inhibition of p21ras signaling, leading to differentiation or apoptosis. In this Phase I trial, 17 patients took POH p.o. three times daily for 14 days of each 28-day cycle. The starting dose of POH was 1600 mg/m2/dose, with escalations to 2100 and 2800 mg/m2/dose in subsequent cohorts. Chronic nausea and fatigue were dose-limiting toxic effects at 2800 mg/m2. Grade 1-2 hypokalemia was common at 2100 and 2800 mg/m2. Although POH could not be detected in plasma, two of its metabolites, dihydroperillic acid (DHPA) and perillic acid (PA), were measured in plasma and urine on days 1 and 15 after the first and last doses of POH, respectively. Both area under the concentration versus time curve and peak plasma concentration (Cmax) values increased with dose and exhibited high intersubject variability. Day 15 DHPA Cmax values ranged from a mean +/- SD of 22.6+/-12 microM at 1600 mg/m2/dose to 42.4+/-15.24 microM at 2800 mg/m2/dose. Corresponding mean +/- SD Cmax values for PA were 433.2+/-245.8 and 774.1+/-439.6 microM. One patient treated at the 2800 mg/m2/dose had markedly prolonged plasma levels of both PA and DHPA and developed grade 3 mucositis. POH treatment did not consistently alter the expression of p21ras, rap1, or rhoA in peripheral blood mononuclear cells obtained from patients treated at the highest dose level. The metabolites PA and DHPA did not change expression or isoprenylation of p21ras in MCF-7 breast or DU145 prostate carcinoma cells at concentrations that exceeded those achieved in patient plasma after POH treatment. We conclude that POH at 1600-2100 mg/m2 p.o. three times daily is well tolerated on a 14-day on/14-day off dosing schedule. Inhibition of p21ras function in humans is not likely to occur after POH administration at safe doses of the present oral formulation.

Phase II study of weekly 5-fluorouracil, cisplatin and vinblastine in advanced non-small cell lung cancer.

The scheduling of chemotherapeutic agents may be important in optimising their antitumour actions. This has been explored in non-Hodgkin lymphoma, osteogenic sarcoma and bladder cancer with improved results using intensive, weekly dosing schemas. We began a phase II study of cisplatin, 5-fluorouracil and vinblastine in non-small cell lung cancer (NSCLC) on a weekly schedule. 38 patients with advanced or metastatic NSCLC were entered; 32 are evaluable for response. 11 patients were treated with 5-fluorouracil 1.5 g/m2 and vinblastine 4 mg/m2 by 24-h continuous infusion, and cisplatin 30 mg/m2 over 30 min, 6-8 h after the start of the infusion. Because of prohibitive myelotoxicity, the next 27 patients received 5-fluorouracil 1.2 g/m2 and vinblastine 3 mg/m2. None had had prior chemotherapy while 6 had had previous radiation therapy. Myelosuppression was the predominant toxic effect. Other side-effects included neuropathy, diarrhoea, mucositis, nausea and vomiting. 32 patients are evaluable for response: there have been 14 partial remissions (44%). Responses have occurred chiefly in lung and lymph nodes. The median survival on this study is 7 months, and responders did not live longer than non-responders. While this regimen is well tolerated by the majority of patients and has a response rate comparable to other active regimens identified in single institution studies, survival does not appear to be enhanced. We conclude that the schedule manipulation described here does not enhance the therapeutic index of these drugs in NSCLC.

Phase I study of paclitaxel and estramustine: preliminary activity in hormone-refractory prostate cancer.

Estramustine phosphate is a unique antimitotic agent that binds to tubulin and microtubule-associated proteins. Preclinically, estramustine combined with other microtubule inhibitors, like vinblastine or paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ), produced additive or greater antimitotic and cytotoxic effects. Clinically, the estramustine/vinblastine combination has significant activity in hormone-refractory prostate cancer. We have begun a phase I study of paclitaxel by 96-hour continuous infusion every 3 weeks combined with daily oral estramustine (600 mg/m2). Eighteen patients with refractory solid tumors have received paclitaxel doses ranging from 80 to 140 mg/m2. Grade 3 or 4 granulocytopenia occurred in one of seven and two of four patients treated at the 120- and 140-mg/m2 dose levels, respectively. The latter two patients experienced grade 3 mucositis and had mean plasma paclitaxel levels exceeding 0.1 mumol/L. Other toxicities, principally nausea and hepatic function abnormalities, have been mild. The apparent steady-state concentrations of paclitaxel 100 and 120 mg/m2 administered with estramustine are similar to those reported for single-agent paclitaxel administered as a 96-hour infusion at doses of 100 and 120 mg/m2. In contrast, at the 140 mg/m2 dose level, paclitaxel concentrations increased throughout the infusion, and steady state was not reached in three of the four patients treated. Objective responses have been observed in two of three patients with adenocarcinoma of the esophagus and in two patients with hormone-resistant prostate cancer and measurable soft tissue metastases. Two additional patients with prostate cancer have been treated with the estramustine/paclitaxel combination, one achieving a major response and the other stable disease. The recommended phase II dose for 96-hour infusional paclitaxel with daily oral estramustine is at least 120 mg/m2. Studies to determine the effect of estramustine on paclitaxel pharmacokinetics are continuing. The antitumor activity observed merits phase II studies of this combination in hormone-resistant prostate cancer and other malignancies.

Paclitaxel plus estramustine in metastatic hormone-refractory prostate cancer.

Combination antimicrotubule therapy with estramustine phosphate (EMP) and vinblastine has reproducible activity in metastatic hormone-refractory prostate cancer (HRPC) with an objective response rate of 31%. Although paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ) by 24-hour infusion was inactive in HRPC, 0.5 to 1.0 nmol/L concentrations of paclitaxel combined with EMP exerted synergistic cytotoxicity in DU-145 androgen-independent human prostate cancer cell lines. Based on these results, we treated 24 patients with HRPC using the combination of paclitaxel 120 to 140 mg/m2 by 96-hour intravenous infusion every 3 weeks plus daily oral EMP at 600 mg/m2/d. Of seven patients with measurable soft tissue metastases, three have attained partial responses and a fourth patient is nearing partial response status. Of 16 patients with bone-only disease evaluated by change in serum prostate-specific antigen levels, 11 patients (68.8%) have had decreases of > or = 50% from pretreatment baseline. The prostate-specific antigen decrease has exceeded 80% in six of 16 (37.5%) patients. For all 23 evaluable patients, the prostate-specific antigen has decreased by > or = 50% in 15 (65.2%) and by > or = 80% in eight (34.7%). Grade 4 leukopenia occurred in one of 21 patients treated at the paclitaxel dose of 120 mg/m2/96 hr and one of three patients treated at 140 mg/m2/96 hr. The incidence of nausea (50%) and peripheral edema (37.5%) was similar to that associated with single-agent EMP. These results demonstrate that 96-hour paclitaxel plus EMP is active in HRPC and provide further evidence that the rational combination of antimicrotubule agents leads to synergistic antitumor activity in HRPC.

Prostacyclin is the major prostaglandin synthesized by bovine retinal capillary pericytes in culture.

Prostaglandin synthesis by bovine retinal pericytes was investigated using high pressure liquid chromatography to separate and identify 3H-labeled prostaglandins released from 3H-arachidonic acid labeled pericyte monolayers. A dominant peak activity corresponding to 6-keto-PGF1 alpha was observed. This peak was eliminated when monolayers were pretreated with cyclooxygenase inhibitors and was augmented when monolayers were stimulated by the calcium ionophore A23187. Suspensions of pericytes and the cell-free media of monolayers incubated with arachidonic acid inhibited adenosine diphosphate-, collagen-, and arachidonic acid-stimulated platelet aggregation in a bioassay for prostacyclin-like activity. This inhibitory activity was unstable at room temperature. Cultures of 7.5 to 10 x 10(5) pericytes (7th passage near-confluence) released nanogram quantities of 6-keto-PGF1 alpha as measured by radioimmunoassay. These results are evidence that prostacyclin is the main prostaglandin synthesized by bovine retinal capillary pericytes in culture. Pericytes may influence the microcirculation via their production and release of this potent vasoactive arachidonic acid metabolite.

Phase I study of phosphonacetyl-L-aspartate, 5-fluorouracil, and leucovorin in patients with advanced cancer.

Low-dose phosphonacetyl-L-aspartate (PALA) may potentiate both 5-fluorouracil (5-FU) incorporation into RNA and thymidylate synthase inhibition by 5-fluorodeoxyuridylate (5-FdUMP). The gastrointestinal toxicity of 5-FU is not increased by PALA administration. Exogenous leucovorin, on the other hand, which enhances thymidylate synthase inhibition, appears to increase the clinical toxicity of 5-FU in a dose-dependent manner. As a result, the clinical use of high-dose leucovorin requires a marked dose reduction of 5-FU. Extracellular leucovorin levels of 1 microM suffice to maximize the enhancement of thymidylate synthase inhibition in several models. We conducted a trial to add leucovorin to the PALA/5-FU regimen. We chose a leucovorin dose that was predicted to yield end-infusion total reduced folate concentrations of 1 microM. The major endpoint was to determine the maximum tolerated dose of 5-FU in this combination. The regimen consisted of 250 mg/m2 PALA given on day 1 and, 24 h later, escalating 5-FU doses ranging from 1,850 to 2,600 mg/m2 admixed with 50 mg/m2 leucovorin and given by 24-h infusion. Courses were repeated weekly. A total of 24 patients with a median performance status of 1 were entered at three dose levels. Diarrhea was dose-limiting; 6/13 patients had grade II or worse diarrhea at 2,600 mg/m2. Dose modification resulted in a mean dose intensity of 2,300 mg/m2 at both the 2,600- and 2,300-mg/m2 dose levels. The 2,300-mg/m2 dose is suitable for phase II testing of this regimen. Three patients (two with breast cancer and 1 with sarcoma) had a partial remission. We measured steady-state concentrations (Css) of 5-FU in 23 patients. The mean Css increased with dose from 0.738 to 1.03 micrograms/ml. Total body clearance did not vary with dose in this range. Patients with grade II or worse diarrhea had a higher mean Css (1.10 +/- 0.19) than those with grade O or I toxicity (0.835 +/- 0.25, P < 0.02). Total bioactive folates (bound and free) were measured using a biological assay. Pretreatment values ranged from 2 to 52 nM and were not predictive of toxicity. End-infusion (23-h) values were somewhat lower than predicted and ranged from 400 to 950 nM. The risk of diarrhea was positively correlated with end-infusion total folate values. In a logistic regression analysis, total folate values obtained at 23 h were a more powerful predictor of diarrhea than were 5-FU Css values.(ABSTRACT TRUNCATED AT 400 WORDS)

Phase I clinical and pharmacologic trial of trimetrexate in combination with 5-fluorouracil.

Based on the synergy of sequential methotrexate (MTX) and 5-fluorouracil (5-FU) in vitro and in vivo and the superior antitumor activity of trimetrexate (TMTX) compared with MTX in preclinical models, we carried out a phase I trial of TMTX and 5-FU (fixed dose, 400 mg/m2 per day), both given as 10-min i.v. infusions daily x 5 days, every 28 days. The TMTX dose was escalated from 3.0 to 14.0 mg/m2 per day. In all, 92 evaluable courses were given to 34 patients, half of whom were heavily pretreated with radiation or cytotoxics. Myelosuppression and mucositis were the dose-limiting toxicities but were not different in heavily or minimally pretreated patients; there were five episodes of moderate to severe mucositis. Rash, fatigue, and diarrhea were mild toxicities. Plasma TMTX elimination was biexponential, with a mean t.1/2 alpha of 0.23 h and a t.1/2 beta of 16.7 h. The area under the plasma TMTX concentration versus time curve increased linearly with dose, suggesting first-order elimination. Total plasma TMTX clearance (mean +/- SD) was 14.3 +/- 5.9 ml/min per m2. Renal clearance accounted for approximately 7% of total clearance, indicating biotransformation as the major route of elimination. TMTX was highly protein-bound (97%). Thus, TMTX can be given with 5-FU (400 mg/m2) on a daily x 5-day bolus schedule at the 12 mg/m2 per day dose level, which was the recommended dose of TMTX as a single agent for phase II studies using the 5-day bolus schedule.

Phase I trial of fluorouracil modulation by N-phosphonacetyl-L-aspartate and 6-methylmercaptopurine ribonucleoside.

Inhibition of pyrimidine and purine synthesis has been demonstrated to potentiate 5-fluorouracil (5-FU) activity in preclinical models. Low-dose phosphonacetyl-L-aspartate (PALA) potentiates the incorporation of 5-FU into RNA, without detectably increasing its toxicity. 6-Methylmercaptopurine riboside (MMPR) results in inhibition of purine biosynthesis with elevation of phosphoribosyl pyrophosphate (PRPP), which in turn is believed to increase the phosphorylation and intracellular retention of 5-FU. We conducted a phase I clinical trial to determine the maximum tolerated dose of 5-FU in combination with low-dose PALA and a biochemically-optimized dose of MMPR. The regimen consisted of PALA 250 mg/m2 given on day 1, followed 24 h later by MMPR 150 mg/m2, and escalating doses of 5-FU from 1625 to 2600 mg/m2 by 24 h continuous infusion. This regimen was repeated weekly. A group of 29 patients with a diagnosis of malignant solid tumor were entered; their median performance status was 1. The dose-limiting toxicity was mucositis, while other gastrointestinal toxicity was minimal. Two patients also experienced ischemic chest pain during the 5-FU infusion. The maximum tolerated dose of 5-FU in this combination was 2600 mg/m2. Several responses were observed including a complete remission in a previously treated breast cancer patient and two partial responses in breast and colon cancer. MMPR pharmacokinetics were obtained from urine analyses in 21 patients on this trial; there was no correlation between the pharmacokinetics of MMPR and the toxicity observed. This regimen was well tolerated and phase II trials are warranted using PALA 250 mg/m2, MMPR 150 mg/m2, and 5-FU 2300 mg/m2 by continuous infusion over 24 h.