Antonello Di Paolo

Biweekly Chemotherapy With Oxaliplatin, Irinotecan, Infusional Fluorouracil, and Leucovorin: A Pilot Study in Patients With Metastatic Colorectal Cancer

PURPOSE To determine the feasibility, recommended doses, plasma pharmacokinetics, and antitumor activity of a biweekly chemotherapy regimen with oxaliplatin (L-OHP), irinotecan (CPT-11), infusional fluorouracil (5-FU), and leucovorin (LV) in metastatic colorectal cancer patients. PATIENTS AND METHODS Patients received CPT-11 followed by L-OHP and LV 200 mg/m(2) and followed by 5-FU 3,800 mg/m(2) as a 48-hour infusion, repeated every 2 weeks. In the first part of the study, an escalation of CPT-11 dose and/or a decrease of the L-OHP dose were planned. Once the recommended doses of CPT-11 and L-OHP were determined, all subsequent patients were treated at the recommended doses. RESULTS Forty-two patients entered the study. CPT-11 175 mg/m(2) and L-OHP 100 mg/m(2) in combination with LV 200 mg/m(2) and 5-FU 3,800 mg/m(2) could be administered with acceptable toxicities; 39 patients were treated at these dose levels. The pharmacokinetics parameters of the agents used and their metabolites did not seem to be influenced by the concomitant use of the other drugs. The most relevant toxicities were diarrhea and neutropenia, with 14% of patients experiencing one episode of febrile neutropenia. In five patients (11.9%) a complete and in 25 (59.5%) a partial response was demonstrated, for an objective response rate of 71.4% (95% confidence interval, 47% to 83%). In 11 patients (26%), a surgical resection of residual disease could be performed. Median progression-free and overall survival times were 10.4 and 26.5 months, respectively. CONCLUSION This biweekly regimen is feasible and has acceptable and manageable toxicities and no apparent relevant pharmacokinetics interactions. This combination is associated with a promising antitumor activity, time to progression, and survival. A phase III randomized trial in Italy planned by the Gruppo Oncologico Nord Ovest has just started.

The pharmacological bases of the antiangiogenic activity of paclitaxel

In the mid 1990s, researchers began to investigate the antiangiogenic activity of paclitaxel as a possible additional mechanism contributing to its antineoplastic activity in vivo. In the last decade, a number of studies showed that paclitaxel has antiangiogenic activity that could be ascribed to the inhibition of either tubule formation or cell migration, and to an antiproliferative effect towards activated endothelial cells. Furthermore, paclitaxel was shown to downregulate VEGF and Ang-1 expression in tumor cells, and to increase the secretion of TSP-1 in the tumor microenvironment. Moreover, the new pharmaceutical formulations of paclitaxel (such as liposome-encapsulated paclitaxel, ABI-007, and paclitaxel entrapped in emulsifying wax nanoparticles) enhanced the in vivo antiangiogenic activity of the drug. Thus, the preclinical data of paclitaxel may be exploited to implement a novel and rational therapeutic strategy to control tumor progression in patients.

Pharmacogenetics of Anticancer Drug Sensitivity in Non-Small Cell Lung Cancer

In mammalian cells, the process of malignant transformation is characterized by the loss or down-regulation of tumor-suppressor genes and/or the mutation or overexpression of proto-oncogenes, whose products promote dysregulated proliferation of cells and extend their life span. Deregulation in intracellular transduction pathways generates mitogenic signals that promote abnormal cell growth and the acquisition of an undifferentiated phenotype. Genetic abnormalities in cancer have been widely studied to identify those factors predictive of tumor progression, survival, and response to chemotherapeutic agents. Pharmacogenetics has been founded as a science to examine the genetic basis of interindividual variation in drug metabolism, drug targets, and transporters, which result in differences in the efficacy and safety of many therapeutic agents. The traditional pharmacogenetic approach relies on studying sequence variations in candidate genes suspected of affecting drug response. However, these studies have yielded contradictory results because of the small number of molecular determinants of drug response examined, and in several cases this approach was revealed to be reductionistic. This limitation is now being overcome by the use of novel techniques, i.e., high-density DNA and protein arrays, which allow genome- and proteome-wide tumor profiling. Pharmacogenomics represents the natural evolution of pharmacogenetics since it addresses, on a genome-wide basis, the effect of the sum of genetic variants on drug responses of individuals. Development of pharmacogenomics as a new field has accelerated the progress in drug discovery by the identification of novel therapeutic targets by expression profiling at the genomic or proteomic levels. In addition to this, pharmacogenetics and pharmacogenomics provide an important opportunity to select patients who may benefit from the administration of specific agents that best match the genetic profile of the disease, thus allowing maximum activity.

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.

Pharmacogenetic determinants of anti-cancer drug activity and toxicity

Cellular responses to anti-cancer agents result from the interaction between drugs, cellular targets and mechanisms of damage repair. Despite the pharmacological advances in the treatment of cancer, the clinical efficacy of chemotherapy is unpredictable in most patients. However, new information on the genetics of cancer delineates strategies by which the genetic background of tumour cells and patients might be profiled to select anti-cancer agents with improved efficacy and tolerability. This article focuses on the application of pharmacogenetics in the characterization of differences in the pharmacokinetics and pharmacodynamics of anti-cancer agents among individuals to define the likelihood of response and reduce the incidence of adverse effects.

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

Abstract 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 μg/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 μg/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.

Pharmacological issues of linezolid: an updated critical review.

Linezolid is the first oxazolidinone agent introduced into clinical practice for use against Gram-positive bacteria that are resistant to β-lactams and glycopeptides, including methicillin (meticillin)-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE). An optimal antibacterial effect is achieved when plasma drug concentrations are above the minimum inhibitory concentration (MIC) [T>MIC] for the entire length of treatment and the ratio between the area under the plasma concentrationtime curve (AUC) and the MIC (AUC/MIC) is greater than 100, as is most commonly obtained with administrationof the standard dosage of linezolid 600 mg twice daily. A wide tissue distribution, including the CNS and respiratory tract, nearly linear pharmacokinetics and good tolerability are additional characteristics of linezolid. However, variability in the drug pharmacokinetics associated with clinical conditions (e.g. sepsis, burn injuries, end-stage renal disease, cystic fibrosis), haemodialysis and/or young age may lower the T>MIC and the AUC/MIC ratio, thus impairing both antibacterial activity and prevention of mutants. In most cases, changes in the dosage or in the schedule of administration (e.g. an additional [third] daily dose) may improve the effectiveness of linezolid. It is worth noting that linezolid could affect its own metabolism as a result of protein synthesis inhibition in mitochondria, and this could lead to high plasma concentrations and an increased risk of non-negligible toxicities. The latter may be reported during long-term administration of linezolid or in the presence of some pathological conditions (e.g. renal disease or kidney transplantation) associated with high plasma drug concentrations. Therefore, treatment optimization should be considered a requirement for more effective and tolerable use of the drug, particularly in special populations.

A pharmacokinetic-based test to prevent severe 5-fluorouracil toxicity

Dihydropyrimidine dehydrogenase (DPD) plays a key role in the catabolism of 5‐fluorouracil (5‐FU) to 5‐fluoro‐5,6‐dihydrouracil (5‐FDHU), and as such, an impairment of DPD has been recognized as an important factor for altered 5‐FU and 5‐FDHU pharmacokinetics, predisposing patients to the development of severe 5‐FU‐associated toxicity. Our objectives were to avoid severe 5‐FU toxicities in patients with greatly impaired 5‐FU and 5‐FDHU pharmacokinetics after the administration of a reduced test dose of 5‐FU and to investigate possible 5‐FU or 5‐FDHU pharmacokinetic parameters of the test dose related to the most common drug toxicities that affect patients after the first cycle of 5‐FU chemotherapy.

Lack of pharmacokinetic bioequivalence between generic and branded amoxicillin formulations. A post‐marketing clinical study on healthy volunteers

AIMS There are concerns about the quality of generic drugs in the postmarketing setting. The aim was to establish whether two generic formulations of amoxicillin, available on the Italian market, fulfil the criteria for clinical pharmacokinetic bioequivalence vs. the branded drug. METHODS Two generic amoxicillin products (generic A and B) were selected among four fast-release tablet formulations available on the Italian market. Twenty-four healthy adult volunteers of either sex participated to a single-dose, randomized, three-treatment, crossover, single-blind bioequivalence study designed to compare generic A and B with branded amoxicillin. Plasma samples were collected at preset times for 24 h after dosing, and assayed for amoxicillin levels by high-performance liquid chromatography. RESULTS Ninety percent confidence intervals of AUC ratios were 0.8238, 1.0502 (ratio 0.9302) and 0.8116, 1.1007 (ratio 0.9452) for generic A and B vs. branded amoxicillin, respectively. Ninety percent confidence intervals of C(max) ratios were 0.7921, 1.0134 (ratio 0.8960) and 0.8246, 1.1199 (ratio 0.9610) for generic A and B vs. branded amoxicillin, respectively. The mean pharmacokinetic profiles showed that the AUC value of branded amoxicillin was 8.5 and 5.4% greater than that estimated for generic A and B, respectively. Few adverse events were recorded; these were not serious and occurred without apparent relationship to any specific amoxicillin formulation. CONCLUSIONS These results indicate that one of the two marketed amoxicillin generics analysed in the present study is not bioequivalent to the brand leader product for C(max) on the basis of single-dose pharmacokinetic assessment.

5-Fluorouracil Pharmacokinetics Predicts Disease-free Survival in Patients Administered Adjuvant Chemotherapy for Colorectal Cancer

Purpose: To evaluate 5-fluorouracil (5-FU) and 5-fluoro-5,6-dihydrouracil (5-FDHU) pharmacokinetics and disease-free survival (DFS) in colorectal cancer patients given 5-FU–based adjuvant chemotherapy within a nonrandomized, retrospective, pharmacokinetic study. Experimental Design: One hundred fifteen patients including 72 men (median age, 63 years; range, 36-79 years) and 43 women (median age, 60 years; range, 36-73 years) received 6 cycles of l-leucovorin 100 mg/m2/day and 5-FU 370 mg/m2/day i.v. boluses (5 days every 4 weeks). Individual plasma concentrations of 5-FU and 5-FDHU were determined on day 1 of the first cycle with a validated high performance liquid chromatography method, and the main pharmacokinetic variables were determined. Follow-up of all patients was extended up to 5 years after the end of adjuvant chemotherapy, and DFS was recorded. Univariate and multivariate analyses were conducted to evaluate any correlation among 5-FU pharmacokinetics, clinical and pathologic variables, and DFS. Results: The area under the time/concentration curve (AUC) of 5-FU was significantly lower in 58 subjects who recurred (7.5 ± 2.9 h × mg/L) with respect to other patients (9.3 ± 4.1 h × mg/L). Furthermore, AUC values lower than 8.4 h × mg/L together with lymph node involvement and the interruption of treatment or reduction of doses were identified as risk factors at univariate analysis. The completion of 6 cycles of adjuvant treatment without dosage modifications was the only independent risk factor at multivariate analysis, despite a trend toward significance for 5-FU AUC values (cutoff value, 8.4 h×mg/L) was observed (P = 0.06). Conclusions: Pharmacokinetics of 5-FU should be regarded as an important factor for predicting disease recurrence in colorectal cancers.