Gemcitabine plus epirubicin plus taxol (GET) in advanced breast cancer: a phase II study

PURPOSE

To investigate the activity of the combination of gemcitabine (G) plus epirubicin (E) and taxol (T), (GET), in metastatic breast cancer, to evaluate the feasibility of this regimen as induction before high dose chemotherapy and to study the pharmacokinetic interactions of these three drugs.

PATIENTS AND METHODS

Metastatic breast cancer patients, with bidimensionally measurable disease were eligible. Treatment consisted of G 1000 mg/sqm days 1 and 4 plus E 90 mg/sqm day 1 plus T 175 mg/sqm/3 h day 1, every 21 days. After six courses of GET, patients aged less than 60 years, in complete or partial remission or stable disease entered a programme of high dose chemotherapy (HDCT), as consolidation treatment.

RESULTS

Thirtysix patients were included in this study. Grade 4 neutropenia was observed in 64% of the patients, with four episodes of febrile neutropenia; 39% of the patients experienced mild to moderate peripheral neuropathy; grade 2 and 3 mucositis occurred respectively in 9 (25%) and 6 (17%) patients. The overall response rate to GET was 92% (95% CI, 77.53%-98.25%); CR 31% and PR 61%. After six courses of GET, 25 patients received HDCT, leading to an overall response rate of 96% with 58% CR. At a median follow up of 25 months (range 8-39), 13 out of 36 patients are progression free and 26 alive. Median progression free survival is 21 months, while median overall survival has not yet been reached. The pharmacokinetic data show that G does not influence the interactions between E and T, while gemcitabine kinetics remains unchanged.

CONCLUSIONS

The results of the present study indicate that the addition of G to E plus T as front line treatment for advanced breast cancer is well tolerated with an ORR of 92%. On the basis of the high activity and interesting progression free and overall survival rates, the GET combination deserves further evaluation in randomized trials.

Inhibition of protein farnesylation enhances the chemotherapeutic efficacy of the novel geranylgeranyltransferase inhibitor BAL9611 in human colon cancer cells

Proteins belonging to the ras superfamily are involved in cell proliferation of normal and neoplastic tissues. To be biologically active, they require post-translational isoprenylation by farnesyl-transferase and geranylgeranyl-transferase. Enzyme inhibition by drugs may thus represent a promising approach to the treatment of cancer. Therefore, the combined effect of BAL9611, a novel inhibitor of geranylgeranylation, and manumycin, a farnesyl-transferase inhibitor, was evaluated on the SW620 human colon cancer cell line which harbours a mutated K-ras gene. BAL9611 and manumycin dose-dependently inhibited SW620 cell growth with 50% inhibitory concentration (IC(50)) of 0.47 +/- 0.03 and 5.24 +/- 1.41 microM (mean +/- SE), respectively. The isobologram analysis performed at the IC(50)level revealed that the combined treatment was highly synergistic with respect to cell growth inhibition. BAL9611 and manumycin were able to inhibit the geranylgeranylation of p21rhoA and farnesylation of p21ras; both drugs inhibited p42ERK2/MAPK phosphorylation, but their combination was more effective than either drug alone. Moreover, the enhanced inhibition of cell growth in vitro by the BAL9611-manumycin combination was also observed in vivo in CD nu/nu female mice xenografted with SW620 tumours. Finally, both drugs were able to induce cell death by apoptosis in vitro and in vivo, as demonstrated by perinuclear chromatin condensation, cytoplasm budding and nuclear fragmentation, and interoligonucleosomal DNA digestion. In conclusion, the inhibition of protein farnesylation enhances the chemotherapeutic effect of BAL9611 in vitro and in vivo in a synergistic fashion, as a result of the impairment of post-translational isoprenylation of proteins and phosphorylation of p42ERK2/MAPK, whose activation is associated with post-translational geranylgeranylation and farnesylation of p21rhoA and p21ras.

High-dose thiotepa and melphalan with hemopoietic progenitor support following induction therapy with epirubicin-paclitaxel-containing regimens in metastatic breast cancer (MBC)

BACKGROUND

Preliminary data from phase III randomized studies have failed to show benefit of HDC given as consolidation after anthracycline and alkylating-based chemotherapy in metastatic breast cancer (MBC). Moderate activity of induction regimens and selection of chemoresistant clones are among the possible reasons for these disappointing results. We therefore have designed a phase II study where high-dose alkylating agents are given as consolidation after an induction treatment including the most active agents (epirubicin and paclitaxel) without alkylating agents.

PATIENTS AND METHODS

Patients with MBC not previously treated with chemotherapy for metastatic disease were eligible. After six courses of epirubicin-paclitaxel +/- gemcitabine patients received a course of thiotepa 600 mg/m2 + melphalan 160 mg/m2 with hemopoietic support. Pharmacokinetic parameters of thiotepa and melphalan were measured and related to treatment outcomes. The L-VEF of the patients was monitored before and after treatment.

RESULTS

Forty-eight patients have been treated. Before HDC 14 patients were in CR, and 34 in PR. A median of 6.92 x 10(6) (range 1.53-16.6) CD34+ cells/kg were reinfused after HDC. Median days (range) to neutrophils > 0.5 x 10(9)/l and platelets > 20,000 x 10(9)/l were 9.5 (9-33) and 10 days (9-32), respectively. Symptomatic CHF was observed in two patients (4.1%). Cmax and AUC of thiotepa showed a linear relationship with time to progression (TTP) and overall survival (OS): r2 = 0.6. After HDC the conversion rate from PR to CR was 44.1%. At five years progression-free and overall survival rates are 37.5% and 65%, respectively. A treatment-related death was observed.

CONCLUSIONS

High-dose thiotepa and melphalan after an epirubicin-paclitaxel-containing treatment is feasible, devoid of significant cardiotoxicity and very active. Pharmacokinetic parameters of high-dose thiotepa might be linked to treatment outcome.

Three novel mutations causing a truncated protein within the RP2 gene in Italian families with X-linked retinitis pigmentosa

X-linked retinitis pigmentosa (XLRP) results from mutations in a number of loci, including RP2 at Xp11.3, and RP3 at Xp21.1. RP2 and RP3 genes have been identified by positional cloning. RP2 mutations are found in about 10% of XLRP patients. We performed a mutational screening of RP2 gene inpatients belonging to seven unrelated families in linkage with the RP2 locus. SSCP analysis detected three conformation variants, within exon 2 and 3. Direct sequencing of exon 2, disclosed a G-->A transition at nucleotide 449 (W150X), and a G-->T transversion in position 547 (E183X). Sequence analysis of exon 3 variant revealed an insertion (853/854insG), leading to a frameshift. In this patient, we detected an additional sequence alteration (A-->G at nucleotide 848, E283G). Each mutation was co-segregating with the disease in the affected family members available for the study. These mutations are expected to introduce a stop codon within the RP2 coding sequence probably resulting in a truncated or unstable protein.

Genetics of drug response to immunosuppressive treatment and prospects for personalized therapy

The use of immunosuppressive agents in the treatment of transplant rejection and autoimmune disorders is gaining momentum, with significant improvements of both graft and patient survival. The individual response to drugs, however, is variable and unexpected toxicity, or impaired activity might be seen, as a result of molecular determinants that eventually dictate how the individual will respond to immunosuppressive agents. This review addresses a number of issues related to pharmacogenetics, and discusses how this approach might be used to improve the clinical efficacy and tolerability of therapeutic options for the management of organ transplantation and autoimmune disorders in the next decade.

Suppression of Fas expression and down-regulation of Fas ligand in highly aggressive human thyroid carcinoma

The Fas-FasL system seems to mediate thyrocyte death in Hashimoto's thyroiditis. In thyroid cancer, down-regulation of bcl-2 seems to alter apoptosis control. We compared the expression of immunoreactive Fas and FasL in normal thyroid with that of tumors ranging from benign to highly aggressive. Fas is essentially not expressed in normal thyrocytes, whereas FasL is expressed in approximately one-third of cases. Expression of both markers is significantly up-regulated in adenoma and in well-differentiated papillary and follicular carcinoma. In contrast, Fas is suppressed and FasL is strongly reduced in the most aggressive histological variants (poorly differentiated and undifferentiated carcinoma). Immunohistochemistry findings have been confirmed by analysis of Fas-FasL mRNA transcripts. In vitro studies showed that the Fas receptor of thyroid tumor cells was functional, because apoptosis was induced by an agonistic Fas antibody. Fas-expressing and Fas-resistant mammary cell lines were used as specificity controls. Together with our previous data inversely relating bcl-2 expression and thyroid tumor grade, the present findings further indicate that apoptotic pathways are altered in thyroid neoplasia. Thus, the Fas-FasL system may represent a marker of tumor aggressiveness.

Cyclins of phases G1, S and G2/M are overexpressed in aneuploid mammary carcinomas

Expression of cyclins A, B1 and D1 in human breast cancer was analyzed using dual-parameter flow cytometry with simultaneous evaluation of the DNA content. The asynchronous MCF-7 breast adenocarcinoma cells were used to implement flow cytometry analysis and to analyze the cell cycle distribution of cyclins. The patterns of the cyclin expression were also analyzed in vivo in fresh tissue specimens of human breast carcinomas. The combined measurement of DNA and cyclins showed a higher cyclin expression in aneuploid (11.5 +/- 2.0%, 4.3 +/- 1.1%, and 19.5 +/- 3.4% positive cells for cyclins A, B, and D1, respectively) than in diploid carcinomas (3.9 +/- 1.2%, 1.1 +/- 0.4%, and 5.0 +/- 1.2% positive cells for cyclins A, B, and D1, respectively). A positive relationship was also found between cyclin A and D1 expression and H(3)-thymidine labeling index. In the in vitro model, the asynchronous growing MCF-7 cells showed a variable number of cells expressing cyclins in an unscheduled way, unrelated to the phase at which these cyclins are expressed in normal cells. A similar condition was also observed in tumors. In conclusion, the data showed a deregulated expression of cyclins in a transformed adenocarcinoma cell line and in breast tumors. Furthermore, overexpression of these proteins is related to the aneuploid and high proliferative activity of human mammary carcinomas.

Comparative pharmacokinetic analysis of 5-fluorouracil and its major metabolite 5-fluoro-5,6-dihydrouracil after conventional and reduced test dose in cancer patients

The aim of this study was to investigate the clinical pharmacokinetics of 5-fluorouracil (5-FU) and its major metabolite 5-fluoro-5,6-dihydrouracil (5-FDHU) in 20 colorectal cancer patients given two dose levels of 5-FU, 250 and 370 mg/m2, administered by i.v. bolus. A reverse-phase high-performance liquid chromatographic method was used for the simultaneous assay of 5-FU and 5-FDHU in plasma samples obtained at baseline and at multiple time points from 5 min to 4 h after 5-FU bolus as well as to assess the activity of dihydropyrimidine dehydrogenase (DPD) in peripheral blood mononuclear cells (PBMCs) before 5-FU dosing. Plasma pharmacokinetic parameters of patients given 250 mg/m2 5-FU were significantly different from those receiving 370 mg/m2; main differences were observed in the trapezoidal areas under the plasma levels-versus-time curve from to to the last measurable concentration (area under the curve, 3.77+/-0.21 versus 13.61+/-2.3 h x microg/ml), peak plasma concentration (Cmax, 18.15+/-1.35 versus 48.41+/-7.69 microg/ml), and total body clearance (CL(TB), 54.64+/-3.54 versus 25.43+/-2.3 l/h/m2). Significant differences were also observed in the main pharmacokinetic parameters of 5-FDHU after 250 and 370 mg/m2 5-FU including the area under the curve from to to 4 h (5.39+/-0.32 versus 8.75+/-1.24 h x microg/ml), Cmax (3.60+/-0.16 versus 5.26+/-0.55 microg/ml) and time to Cmax (Tmax, 0.45+/-0.03 versus 0.69+/-0.06 h). The mean DPD activity in PBMCs in this group of patients was 205.7+/-36.4 pmol of 5-FDHU/min/mg of protein and was within the normal range; however, no significant correlations were found between 5-FU or 5-FDHU pharmacokinetic parameters at two dose levels and DPD activity of PBMCs. The results of the present study provide the first detailed comparison of the distribution of 5-FU and its major metabolite 5-FDHU at the therapeutic level as well as at reduced test dose levels to obtain pharmacokinetic data to be used as reference values for the identification of patients at risk of major 5-FU toxicity due to impaired metabolism to 5-FDHU.

Variable correlation between 6-mercaptopurine metabolites in erythrocytes and hematologic toxicity: implications for drug monitoring in children with acute lymphoblastic leukemia

Nineteen pediatric patients affected by acute lymphoblastic leukemia (ALL) were examined weekly with respect to 6-mercaptopurine nucleotide (6-MPN) and 6-thioguanine nucleotide (6-TGN) levels in erythrocytes during the course of maintenance treatment with 6-MP 50 mg/m2 per d and results were related to various parameters of bone marrow function to assess, in the same individual, the level of reliability of 6-MP metabolites in predicting a later change in peripheral blood cell counts. Median values for 6-MPN and 6-TGN were 57 and 200 pmol/8 x 10(8) erythrocytes, respectively, as measured by reversed-phase high-performance liquid chromatography (HPLC). 6-TGN levels in erythrocytes were inversely related with white blood cell count (r = -0.463, p < 0.0001, n = 361), absolute neutrophil count (r = -0.386, p < 0.0001, n = 347), erythrocyte (r = -0.354, p < 0.0001, n = 287), and platelet counts (r = -0.24, p < 0.0001, n = 319) in the majority of patients (n = 10-12), while no correlation was found for 6-MPN. In the remaining children, no evidence of correlation was demonstrated between 6-TGN levels and myelotoxicity. The results confirm the role of 6-TGN as the reference cytotoxic metabolite for evaluating the exposure to 6-MP and identifying treatment compliance in ALL children but indicate the limits of a follow-up based solely on metabolite levels and suggest that a more correct approach remains the double monitoring of 6-TGN and blood cell count with differential.

Phase I and pharmacologic study of weekly gemcitabine and paclitaxel in chemo-naïve patients with advanced non-small-cell lung cancer

BACKGROUND

Gemcitabine (GEM) and paclitaxel (TAX) are active, non-cross-resistant drugs in non-small-cell lung cancer (NSCLC). We performed a phase I study to determine the maximum-tolerated dose (MTD), antitumor activity and pharmacokinetics of GEM and TAX given weekly in chemo-naïve patients with advanced NSCLC.

PATIENTS AND METHODS

Escalating doses of GEM (800-2000 mg/m2) and TAX (60-100 mg/m2) were administered on days 1, 8, 15 every 4 weeks to 35 patients with advanced NSCLC. Plasma pharmacokinetics of TAX and GEM was assessed at the three higher dose-levels.

RESULTS

Dose-escalation was discontinued in absence of MTD because of increased cumulative toxicity leading to dose modification or treatment delay at levels 6 and 7 (TAX 100 mg/m2 plus GEM 1750 and, respectively, 2000 mg/m2). Hematological toxicity included grade 4 neutropenia in 3% of cycles, grade 3 thrombocytopenia in one cycle and febrile neutropenia in three cycles. Maximal non-hematological toxicity was grade 3 elevation in serum transaminases and grade 2 neuro-sensory toxicity in 8% and 5% of cycles, respectively. At the two higher dose-levels a non-linear pharmacokinetics of GEM was observed with a remarkable variability of Cmax and AUC. No pharmacokinetic interactions were reported. Objectives responses were seen at all dose levels, with an overall response rate of 43% (95% confidence interval (95% CI): 25.5%-62.6%) in 30 evaluable patients.

CONCLUSIONS

The weekly administration of GEM and TAX is very well tolerated, and has shown promising antitumor activity in NSCLC. In view of the cumulative toxicity and of the pharmacokinetic profile of GEM, doses of 1500 mg/m2 of GEM and 100 mg/m2 of TAX are recommended for phase II studies.

Manumycin inhibits ras signal transduction pathway and induces apoptosis in COLO320-DM human colon tumour cells

The aim of the present study was to assess the cytotoxicity of manumycin, a specific inhibitor of farnesyl:protein transferase, as well as its effects on protein isoprenylation and kinase-dependent signal transduction in COLO320-DM human colon adenocarcinoma which harbours a wild-type K-ras gene. Immunoblot analysis of isolated cell membranes and total cellular lysates of COLO320-DM cells demonstrated that manumycin dose-dependently reduced p21 ras farnesylation with a 50% inhibitory concentration (IC50) of 2.51 +/- 0.11 microM and 2.68 +/- 0.20 microM, respectively, while the geranylgeranylation of p21 rhoA and p21rap1 was not affected. Manumycin dose-dependently inhibited (IC50 = 2.40 +/- 0.67 microM) the phosphorylation of the mitogen-activated protein kinase/extracellular-regulated kinase 2 (p42MAPK/ERK2), the main cytoplasmic effector of p21ras, as well as COLO320-DM cell growth (IC50 = 3.58 +/- 0.27 microM) without affecting the biosynthesis of cholesterol. Mevalonic acid (MVA, 100 microM), a substrate of the isoprenoid synthesis, was unable to protect COLO320-DM cells from manumycin cytotoxicity. Finally, manumycin 1-25 microM for 24-72 h induced oligonucleosomal fragmentation in a dose- and time-dependent manner and MVA did not protect COLO320-DM cells from undergoing DNA cleavage. The present findings indicate that the inhibition of p21ras processing and signal transduction by manumycin is associated with marked inhibition of cell proliferation and apoptosis in colon cancer cells and the effect on cell growth does not require the presence of a mutated ras gene for maximal expression of chemotherapeutic activity.

The gemcitabine/epirubicin/paclitaxel combination in advanced breast cancer

The purpose of this study was to determine the response rate of the gemcitabine/epirubicin/paclitaxel combination (GET) and its feasibility as induction chemotherapy before high-dose consolidation treatment in patients with metastatic breast cancer. Patients received gemcitabine 1,000 mg/m2 on days I and 4, epirubicin 90 mg/m2 on day 1, and paclitaxel 175 mg/m2 on day I every 3 weeks for up to eight courses. After six courses of GET, responding patients or those with stable disease entered a high-dose chemotherapy program. All 36 enrolled patients were evaluated for toxicity and response. The GET combination was well tolerated, with myelosuppression the being most common toxicity; grade 4 neutropenia was reported in 56% of patients. The overall response rate was 89% (95% confidence interval, 73.4% to 96.9%), with a 28% complete response rate. The high-dose chemotherapy program resulted in a response rate of 92% and a complete response rate of 44%. As a result of the promising activity demonstrated in this phase II study with GET and following high-dose chemotherapy, three related studies are planned: an in vitro study evaluating the possible synergism of paclitaxel and gemcitabine, a phase III study comparing GET with epirubicin/paclitaxel in metastatic breast cancer, and a phase II trial evaluating GET in patients with operable breast cancer.

[Preclinical pharmacology and clinical uses of topotecan]

Topotecan, a soluble semisynthetic derivative of camptothecin, is a specific inhibitor of topoisomerase I and is endowed of potent antiproliferative effect in vitro and in vivo on tumoral cell lines as well as on endothelial cells. Moreover, topotecan is able to interfere with the development of blood vessels in many in vivo experimental models. During the last years, several phase I clinical studies have demonstrated that the five-daily schedule is the most effective for the treatment of neoplastic diseases of children and adults. In particular, the best clinical results have been obtained in patients affected by metastatic ovarian cancer, small cell (SCLC) and non-small cell lung carcinoma (NSCLC), as well as mammary and gastrointestinal neoplasms. High response rates have been observed in myelodysplastic syndromes and myeloma. The clinical effectiveness of topotecan has been also demonstrated in ovarian carcinoma, even after failure of first or second line chemotherapy and in SCLC, where the response rate is 39%, while the percentage decreases up to 7% in case of drug resistance, with a median survival of 5.4 months. Toxicologic profile of topotecan is foreseeable and manageable, and the most frequent and severe toxicity is represented by myelosuppression. Leukopenia and neutropenia, which follow the administration of topotecan, are non-cumulative and self-limiting and unfrequently complicated by infections, whereas non-hematologic toxicities are uncommon and generally of mild-to-moderate degree. Topotecan is under continuous clinical evaluation for the treatment of neoplasms other than those reported above, alone or in combination with antineoplastic drugs in poly-chemotherapeutic protocols.

Cardiotoxicity of epirubicin/paclitaxel-containing regimens: role of cardiac risk factors

PURPOSE

To evaluate the incidence of clinically relevant cardiac toxicity after treatment with epirubicin/paclitaxel-containing regimens in patients with metastatic breast cancer and to identify high-risk patients in whom the benefit of chemotherapy may be negated by the occurrence of congestive heart failure (CHF).

PATIENTS AND METHODS

A total of 105 patients who were referred for epirubicin/paclitaxel treatment were included in this study. Treatment regimens were as follows: (1) epirubicin 90 mg/m(2) plus paclitaxel 135 to 225 mg/m(2) over 3 hours (n = 76); and (2) gemcitabine 1,000 mg/m(2) on days 1 and 4 plus epirubicin/paclitaxel (n = 29). The occurrence of CHF was detected by physical examination, and left ventricular function was evaluated by bidimensional echocardiography to support the diagnosis. Cardiac risk factors examined in this study included age, prior radiotherapy to the chest, hypertension, and diabetes.

RESULTS

No patient experienced CHF while on treatment. Nine patients (9%) developed CHF after cumulative epirubicin doses of 1,080 mg/m(2) (n = 4), 720 mg/m(2) (n = 2), 630 mg/m(2) (n = 1), and 540 mg/m(2) (n = 2). One of the two patients who developed CHF after a cumulative epirubicin dose of 540 mg/m(2) had received consolidation with high-dose chemotherapy. Median time to appearance of cardiologic symptoms was 3 months after the end of treatment (range, 3 to 6 months). Overall, the incidence of CHF was 13% and 4% in patients with or without cardiac risk factors, respectively. The cumulative risk of developing CHF was estimated as 7.7% at a cumulative doses of 720 mg/m(2) and 48.7% at a cumulative dose of 1,080 mg/m(2).

CONCLUSION

This study shows that the incidence of CHF after an epirubicin/paclitaxel regimen is low up to cumulative epirubicin doses of 990 mg/m(2), thus allowing the safe administration of this regimen even in patients who received epirubicin in the adjuvant setting. However, the risk of developing CHF increases when a cumulative dose exceeding 990 mg/m(2) is reached, concomitantly with the presence of an additional cardiac risk factor.

Infusions of fluorouracil and leucovorin: effects of the timing and semi-intermittency of drug delivery

Preclinical and clinical studies have demonstrated that the circadian modulation of 5-FU delivery may reduce toxicities and improve antitumor activity. However, the relative importance of the timing of 5-FU delivery has not been clinically addressed. The aims of this study were to determine the toxicities, the maximum tolerable doses and the activity of a regimen with 5-fluorouracil (5-FU) and leucovorin (LV) administered as a 14-day continuous infusion according to a flat or three different chronomodulated rhythms in patients with metastatic gastrointestinal carcinomas. A total of 113 patients entered the study and their characteristics were comparable among the four groups. Toxicities included mainly stomatitis and diarrhea, and a reduced toxicity was observed in all the three chronogroups that allowed the delivery of higher dose intensities. Response rates were not significantly different among the four groups. These results suggest that a reduction in 5-FU+LV toxicity and an increase in 5-FU dose intensity can be obtained by a nonsinusoidally circadian modulated infusion. However, the reduction in toxicity observed seems to be dependent mainly on the quasi-intermittency and not on the timing of 5-FU+LV delivery.

Pharmacokinetic optimisation of treatment schedules for anthracyclines and paclitaxel in patients with cancer

The integration of paclitaxel into chemotherapy regimens with anthracyclines offers a new opportunity for devising effective therapy for patients with breast cancer. High response rates have been obtained by combining epirubicin or doxorubicin with paclitaxel. The pharmacokinetic analysis of paclitaxel and anthracyclines, as well as the identification of relationships with their pharmacodynamics, represents a rational approach for treatment optimisation. A schedule-dependent interaction between paclitaxel and anthracyclines has been demonstrated in clinical pharmacokinetic studies. In patients given paclitaxel 125 to 200 mg/m2 as 3- to 24-hour infusions in combination with doxorubicin 48 to 60 mg/m2 as a 48-hour infusion or intravenous bolus, the peak plasma drug concentration (Cmax) of doxorubicin increased significantly and drug clearance was reduced in the sequence paclitaxel-->doxorubicin as compared with doxorubicin-->paclitaxel. The schedule paclitaxel-->doxorubicin was more toxic as compared with doxorubicin-->paclitaxel, and an incidence of 18 to 20% of congestive heart failure was observed in patients with breast cancer given doxorubicin 60 mg/m2 followed by paclitaxel 125 to 200 mg/m2. Likewise, patients given epirubicin 90 mg/m2 had a sudden rebound of epirubicinol plasma concentrations shortly after the start of infusion of paclitaxel 200 mg/m2, with a significant increase in the area under the concentration-time curve (AUC) of epirubicinol as compared with epirubicin alone (1.27 +/- 0.2 vs 0.61 +/- 0.1 mumol/L.h). Moreover, the severity of the myelosuppression induced by paclitaxel, as defined by a sigmoid maximum effect (Emax) relationship between the decrease in neutrophil count and the duration of drug plasma concentrations above the threshold value of 0.1 mumol/L, was significantly enhanced by epirubicin. Finally, chemotherapy with paclitaxel and anthracyclines may be improved by designing pharmacologically guided regimens in order to control the extent of pharmacokinetic interaction and reduce the risk of severe toxicity while maintaining the therapeutic efficacy of the combination. Future protocols should explore the activity of a prolonged paclitaxel infusion in association with an anthracycline separated from the taxane by a washout time interval in order to minimise the inhibitory effects exerted by paclitaxel on P-glycoprotein-mediated biliary clearance of anthracyclines, the most likely cause of pharmacokinetic interaction.

Suramin in combination with weekly epirubicin for patients with advanced hormone-refractory prostate carcinoma

BACKGROUND

Suramin and epirubicin are both active agents in the treatment of patients with hormone-refractory advanced prostate carcinoma, with demonstrated antitumor synergism in vitro on human prostate carcinoma cells and different dose-limiting toxicities. The authors conducted this Phase II study to determine the feasibility, toxicity, and antitumor activity of suramin in combination with epirubicin.

METHODS

Only patients with hormone-independent advanced prostate carcinoma who had progressive disease after the last therapeutic maneuver they had undergone, including antiandrogen withdrawal, entered the study. Suramin was administered initially as a 6-day continuous infusion for 10 consecutive weeks and then for 6 days every 28 days for a maximum of 6 months. Doses were determined by a computer-assisted dosing system that used Bayesian pharmacokinetics to maintain suramin plasma concentrations of 200-250 microg/mL. Cortisone acetate 25 mg, administered at 8 a.m. and 8 p.m. daily, was begun 4 weeks after the initiation of suramin therapy. Epirubicin 25 mg/m2 was given as a weekly intravenous bolus beginning on Day 1 and was continued for a maximum of 6 months.

RESULTS

Twenty-six patients entered the study. Toxicities mainly included World Health Organization Grade 1-2 nausea, fatigue, anorexia, neutropenia, peripheral neuropathy, creatinine elevation, proteinuria, and prolonged prothrombin time, whereas Grade 3 toxicities were uncommon. Among 11 patients with measurable disease, 3 (27%) demonstrated an objective response. Among 24 patients evaluated for prostate specific antigen (PSA) response, 8 (33%; 95% confidence interval 16-55%) had a > or =50% decrease in PSA levels, which lasted a median of 32 (range, 8-52) weeks. Median progression free and overall survival were both 8 months.

CONCLUSIONS

The combination of suramin and epirubicin used in the current study is feasible, is associated with moderate toxicities, and has antitumor activity in advanced hormone-refractory prostate carcinoma. However, the results obtained with this combination do not represent major improvements in the treatment of patients with this disease, compared with suramin or epirubicin alone or other available treatments.

An improved HPLC method for therapeutic drug monitoring of daunorubicin, idarubicin, doxorubicin, epirubicin, and their 13-dihydro metabolites in human plasma

A single high-performance liquid chromatography (HPLC) method, suitable for the analysis of daunorubicin, idarubicin, doxorubicin, epirubicin, and their 13-dihydro metabolites is validated in the present study. Preparation of plasma samples was performed by a first extraction of analytes with a chloroform/1-heptanol mixture (9:1) and reextraction with ortophosphoric acid 0.1 M. The chromatographic analysis was carried out by reversed-phase isocratic elution of anthracyclines with a Supelcosil LC-CN 5 mm column (25 cm x 4.6 mm internal diameter; Supelco) and detection was accomplished by spectrofluorimetry at excitation and emission wavelengths of 480 and 560 nm, respectively. All anthracyclines eluted within 15 minutes of injection and the method appeared to be specific, because the chromatographic assay did not show interferences at the retention time of analytes. The linearity, evaluated over a concentration range of 0.4-10,000 ng/mL, gave regression coefficients better than 0.999, with recoveries of doxorubicin-doxorubicinol and epirubicin-epirubicinol of 67%-109% and 61%-109% respectively, and 93%-109% for the other compounds. The limits of detection and quantification were 0.4 ng/mL in a 50-mL sample (40 pg/injection) for all anthracyclines tested. The method proved to be precise and accurate, as the within-day and between-day coefficients of variation were less than 10% and the accuracy of the assay was in the range of 91%-107%. Overall results indicate that it is feasible to analyze all the anthracyclines used in clinical practice and their major metabolites with a single optimized method, thereby simplifying their monitoring in chemotherapeutic regimens of cancer patients.

Metabolism of 6-mercaptopurine in the erythrocytes, liver, and kidney of rats during multiple-dose regimens

PURPOSE

To describe the metabolism of 6-mercaptopurine (6-MP) in erythrocytes and tissues of rats after repeated administration of 6-MP at two dose levels and to provide evidence that in vivo modulation of 6-MP anabolism can be obtained by simultaneous treatment with ribavirin or hydroxyurea, two inhibitors of enzymes involved in the bioactivation of 6-MP to the active 6-thioguanine nucleotides (6-TGN).

METHODS

Rats were treated i.p. with 6-MP at 12.5 and 25 mg/kg daily for 12 days and erythrocyte, liver, and kidney levels of 6-mercaptopurine nucleotides (6-MPN) and 6-TGN were investigated during the accumulation phase and for 50 days after the end of treatment. In combination studies, ribavirin at 75 and 100 mg/kg per day (for 6-MP, 25 and 12.5 mg/kg per day) or hydroxyurea at 200 mg/kg per day were given i.p. for 12 days. The measurements of thionucleotide levels in rat samples were performed by high-pressure liquid chromatography (HPLC).

RESULTS

The maximal concentration (Cmax) and the area under the concentration versus time curve (AUC) of 6-MPN and 6-TGN in erythrocytes and tissues increased significantly after the administration of 6-MP at 25 mg/kg per day as compared with 12.5 mg/kg per day. In particular, the Cmax and AUC of 6-TGN in erythrocytes of rats treated with 6-MP at 25 mg/kg per day were approximately 5-fold higher than the 6-TGN values observed following treatment at 12.5 mg/kg per day. Moreover, 6-TGN levels in erythrocytes were significantly higher than those of 6-MPN (910.9+/-53.1 and 286.8+/-23.4 pmol/8 x 10(8) cells for 6-TGN and 6-MPN, respectively, P < 0.05) after treatment with 6-MP at 25 mg/kg per day. The administration of ribavirin, an inhibitor of inosine monophosphate dehydrogenase, in association with 6-MP increased the amount of 6-MPN detected in erythrocytes and tissues while reducing 6-TGN levels in samples. The production and accumulation of 6-MPN and 6-TGN were increased in erythrocytes and tissues by hydroxyurea, an inhibitor of ribonucleotide reductase. Finally, a significant correlation between thionucleotide concentrations and erythrocyte counts was observed.

CONCLUSION

The overall results demonstrate that 6-MP is actively metabolized in rats and that its biotransformation can be modulated by agents acting on enzymes of the purine metabolism, resulting in significant changes in erythrocyte and tissue levels of 6-MPN and 6-TGN. These findings provide evidence that the rat is a suitable model for investigation of the metabolism of 6-MP and its possible pharmacologic modulation.

Inhibitory effect of suramin in rat models of angiogenesis in vitro and in vivo

The aim of the present study was to test the ability of the chemotherapeutic agent suramin to inhibit angiogenesis in experimental models in vitro and in vivo. In the culture of rat aortic rings on fibronectin, suramin dose-dependently inhibited vascular cell growth, achieving the maximal effect (mean - 88% versus controls, P < 0.05) at 400 microg/ml. Image analysis showed that suramin could inhibit microvessel sprouting in fibrin from rat aortic rings as evaluated by the ratio between the cellular area and the mean gray value of the sample (sprouting index); suramin at 50 microg/ml significantly reduced the sprouting index from the control value of 0.35+/-0.04 to 0.14+/-0.02 mm2/gray level (P < 0.05). Likewise, the area occupied by cells was 19.2+/-1.8 mm2 as compared with 41.8+/-4.2 mm2 in controls (P < 0.05). In the rat model of neovascularization induced in the cornea by chemical injury, suramin at 1.6 mg/eye per day reduced the length of blood vessels (0.7+/-0.1 mm as compared with 1.5+/-0.1 mm in controls, P < 0.05). In the same model the ratio between the area of blood vessels and the total area of the cornea (area fraction score) was decreased by suramin from 0.19+/-0.02 in controls to 0.03+/-0.003 (P < 0.05). Suramin given i.p. at 30 mg/ kg per day markedly inhibited the neovascularization induced in the rat mesentery by compound 48/80 or conditioned medium from cells secreting the angiogenic protein fibroblast growth factor-3 (FGF-3). The area fraction score in control rats treated with compound 48/80 was 0.31+/-0.03, and this was reduced to 0.07+/-0.01 by suramin (P < 0.05). After i.p. administration of FGF-3 the area fraction score was reduced by suramin from 0.29+/-0.03 to 0.05+/-0.01 (P < 0.05). These results provide evidence that suramin exerts inhibitory effects on angiogenesis in both in vitro and in vivo models.

The heparan sulfate suleparoide inhibits rat corneal angiogenesis and in vitro neovascularization

The purpose of this study was to evaluate the inhibitory activity of the heparan sulfate suleparoide on vascular cell growth in vitro and angiogenesis in vivo. Human HUV-EC-C endothelial cell proliferation and microvessel sprouting from cultured rat aortic rings were assayed by the bioreduction of 3-[4,5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide. The inhibition of the neoforming capillary network in the chorioallantoic membrane of chick embryo (CAM) was evaluated by agarose disks containing suleparoide and applied on the CAM surface. AgNO3/KNO3 injury was used to induce corneal neovascularization and to evaluate the therapeutic effect of topical suleparoide, while the involvement of bFGF in angiogenesis was evidenced by immunohistochemistry of corneal tissue. Quantitation of angiogenesis in the CAM and the cornea was accomplished by image analysis. Suleparoide dose-dependently inhibited HUV-EC-C cell proliferation (50% inhibitory concentration [IC50], 197.5+/-15.2 microg ml-1) and reduced microvessel sprouting in vitro (IC50, 351+/-22 microg ml-1). Likewise, suleparoide 150 microg in agarose disks produced an avascular area of 19.7+/-2.7% of the total area of the CAM (P<0.05 as compared to controls). bFGF levels were significantly enhanced in the cornea after AgNO3/KNO3 injury, and the increase appeared to be time-dependent (25.6+/-1.8 and 43.2+/-7.4%, vs. uninjured controls after 24 hr and 48 hr, respectively, P<0.05). Suleparoide 4.8 mg eye-1 day-1 for six days reduced the length of blood vessels and the area of the cornea infiltrated by them (59.6+/-7.4% decrease vs. controls, P<0.05). These results demonstrate that suleparoide is an active agent against angiogenesis and suggest that the therapeutic effect of the drug could be of value to treat corneal neovascularization.

Geranylgeraniol overcomes the block of cell proliferation by lovastatin in C6 glioma cells

It is well documented that 3-hydroxy-3-methylglutaryl-CoA reductase inhibitors prevent cultured mammalian cells from progressing through the cell cycle, suggesting a critical role for a mevalonate-derived product. Recently, it has been shown that free geranylgeraniol (GG-OH) and farnesol (F-OH) can be utilized by C6 glioma cells for protein isoprenylation. The ability of GG-OH and F-OH to restore protein geranylgeranylation or farnesylation selectively has enabled us to examine the possibility that mevalonate is essential for cell proliferation because it is a precursor of farnesyl pyrophosphate or geranylgeranyl pyrophosphate, the isoprenyl donors involved in the posttranslational modification of key regulatory proteins. In this study we report that GG-OH, as well as mevalonate, overcomes the arrest of cell proliferation of C6 glioma cells treated with lovastatin, as assessed by increased cell numbers and a stimulation in [3H]thymidine incorporation. The increase in cell number and [3H]thymidine incorporation were significantly lower when F-OH was added. Under these conditions [3H]mevalonate and [3H]GG-OH are actively incorporated into a set of isoprenylated proteins in the size range of small, GTP-binding proteins (19-27 kDa) and a polypeptide with the molecular size (46 kDa) of the smaller isoform of 2 ',3'-cyclic nucleotide 3'-phosphodiesterase. Analysis of the proteins metabolically labeled by [3H]mevalonate and [3H]GG-OH reveals the presence of labeled proteins containing geranylgeranylated cysteinyl residues. Consistent with geranylgeranylated proteins playing a critical role in the entry of C6 cells into the cell cycle, a (phosphonoacetamido)oxy derivative of GG-OH, a drug previously shown to interfere with protein geranylgeranylation, prevented the increase in cell number when mevalonate or GG-OH was added to lovastatin-treated cells. These results strongly suggest that geranylgeranylated proteins are essential for progression of C6 cells into the S phase of the cell cycle and provide the first evidence that the "salvage" pathway for the utilization of the free isoprenols is physiologically significant in the CNS.

Ultrastructural and biochemical evidence of apoptosis induced by a novel inhibitor of protein geranylgeranylation in human MIA PaCa-2 pancreatic cancer cells

Analogs of geranylgeranyl diphosphate (GGdP) have been demonstrated to inhibit the geranylgeranylation of proteins, producing cytotoxic activity in human prostate cancer cells. A detailed study is reported on the programmed cell death in vitro of human exocrine pancreas cancer cells (MIA PaCa-2) induced by the most active compound of this series of geranylgeranylation inhibitors, the dipotassium salt of (E,E,E)[2-oxo-2-[[(3,7,11,15-tetramethyl-2, 6,10,14-hexadecatetraenyl)-oxy]amino]ethyl] phosphonic acid (BAL 9504), using transmission and scanning electron microscopy (SEM). The results show that, after 72 h of treatment with BAL 9504, 25 microM, most MIA PaCa-2 cells display the typical morphological features of apoptosis, including condensation of nuclear chromatin, dilation of endoplasmic reticulum, and fragmentation of both nucleus and cytoplasm, giving rise to small membrane-bound vesicles (apoptotic bodies); surface protrusions and blebs are well demonstrated by SEM. The electrophoresis showed the presence of various bands corresponding to fragmented DNA of 180 base pairs, or multiples of this length, thus indicating that BAL 9504 effectively induces apoptosis. The present study provides the first evidence that inhibition of protein geranylgeranylation produces apoptosis in human MIA PaCa-2 exocrine pancreas cancer cells.

Pharmacokinetic optimisation of the treatment of cancer with high dose zidovudine

The thymidine analogue zidovudine is currently used for the treatment of HIV-infected patients, as the early development of the drug as an anticancer agent yielded modest results. A comprehensive preclinical analysis, however, showed that inhibitors of de novo thymidylate synthesis, including fluorouracil and methotrexate, enhanced the antiproliferative activity of zidovudine in cancer cells. Significant inhibition of tumour growth was obtained in mice bearing human colon cancer xenografts and given intraperitoneal zidovudine 300 to 600 mg/kg weekly in combination with methotrexate 87.5 mg/kg or intraperitoneal fluorouracil 85 mg/kg, and in pharmacokinetic studies high peak drug plasma concentrations (Cmax) of zidovudine were obtained, ranging from 610.3 to 1698.8 mumol/L. In order to exploit the therapeutic activity of zidovudine, phase I and II clinical studies were designed in combination with fluorouracil and the pharmacokinetic-pharmacodynamic profile of zidovudine was investigated. Clinical responses were obtained in patients treated intravenously with bolus fluorouracil 500 mg/m2, leucovorin and short (90 to 120 minutes) infusions of high dose zidovudine (up to 10 g/m2), generating drug Cmax similar to those obtained in preclinical models. However, in chemotherapy-pretreated patients receiving high dose zidovudine by the oral route (1 to 9 g/m2/day) or 48-hourly continuous intravenous infusion (2 to 20 g/m2/day) in combination with fluorouracil and leucovorin, treatment failures were observed despite high systemic exposure, described as the area under the plasma concentration-time curve and the occurrence of DNA strand breaks in peripheral blood mononucleated cells, the biological expression of zidovudine activity. In conclusion, preclinical and clinical evidence suggest that the schedule of administration of zidovudine is a requisite for the expression of its activity, indicating the importance of concentration-monitored trials to optimise chemotherapy dose administration in patients. The likelihood of tumour response appears to be related to the achievement of high peak plasma concentrations of zidovudine, and constant infusions appear less likely to produce clinical results.