Drug distribution and pharmacokinetic/pharmacodynamic relationship of paclitaxel and gemcitabine in patients with non-small-cell lung cancer

Prediction Model for Severe Thrombocytopenia Induced by Gemcitabine Plus Cisplatin Combination Therapy in Patients with Urothelial Cancer

BACKGROUND

Chemotherapy-induced thrombocytopenia is often a use-limiting adverse reaction to gemcitabine and cisplatin (GC) combination chemotherapy, reducing therapeutic intensity, and, in some cases, requiring platelet transfusion.

OBJECTIVE

A retrospective cohort study was conducted on patients with urothelial cancer at the initiation of GC combination therapy and the objective was to develop a prediction model for the incidence of severe thrombocytopenia using machine learning.

METHODS

We performed receiver operating characteristic analysis to determine the cut-off values of the associated factors. Multivariate analyses were conducted to identify risk factors associated with the occurrence of severe thrombocytopenia. The prediction model was constructed from an ensemble model and gradient-boosted decision trees to estimate the risk of an outcome using the risk factors associated with the occurrence of severe thrombocytopenia.

RESULTS

Of 186 patients included in this study, 46 (25%) experienced severe thrombocytopenia induced by GC therapy. Multivariate analyses revealed that platelet count ≤ 21.4 (×104/µL) [odds ratio 7.19, p < 0.01], hemoglobin ≤ 12.1 (g/dL) [odds ratio 2.41, p = 0.03], lymphocyte count ≤ 1.458 (×103/µL) [odds ratio 2.47, p = 0.02], and dose of gemcitabine ≥ 775.245 (mg/m2) [odds ratio 4.00, p < 0.01] were risk factors of severe thrombocytopenia. The performance of the prediction model using these associated factors was high (area under the curve 0.76, accuracy 0.82, precision 0.68, recall 0.50, and F-measure 0.58).

CONCLUSIONS

Platelet count, hemoglobin level, lymphocyte count, and gemcitabine dose contributed to the development of a novel prediction model to identify the incidence of GC-induced severe thrombocytopenia.

Addressing the Clinical Importance of Equilibrative Nucleoside Transporters in Drug Discovery and Development

The US Food and Drug Administration (FDA), European Medicines Agency (EMA), and Pharmaceuticals and Medical Devices Agency (PMDA) guidances on small-molecule drug-drug interactions (DDIs), with input from the International Transporter Consortium (ITC), recommend the evaluation of nine drug transporters. Although other clinically relevant drug uptake and efflux transporters have been discussed in ITC white papers, they have been excluded from further recommendation by the ITC and are not included in current regulatory guidances. These include the ubiquitously expressed equilibrative nucleoside transporters (ENT) 1 and ENT2, which have been recognized by the ITC for their potential role in clinically relevant nucleoside analog drug interactions for patients with cancer. Although there is comparatively limited clinical evidence supporting their role in DDI risk or other adverse drug reactions (ADRs) compared with the nine highlighted transporters, several in vitro and in vivo studies have identified ENT interactions with non-nucleoside/non-nucleotide drugs, in addition to nucleoside/nucleotide analogs. Some noteworthy examples of compounds that interact with ENTs include cannabidiol and selected protein kinase inhibitors, as well as the nucleoside analogs remdesivir, EIDD-1931, gemcitabine, and fialuridine. Consequently, DDIs involving the ENTs may be responsible for therapeutic inefficacy or off-target toxicity. Evidence suggests that ENT1 and ENT2 should be considered as transporters potentially involved in clinically relevant DDIs and ADRs, thereby warranting further investigation and regulatory consideration.

In Vitro Screening of a 1280 FDA-Approved Drugs Library against Multidrug-Resistant and Extensively Drug-Resistant Bacteria

Alternative strategies against multidrug-resistant (MDR) bacterial infections are suggested to clinicians, such as drug repurposing, which uses rapidly available and marketed drugs. We gathered a collection of MDR bacteria from our hospital and performed a phenotypic high-throughput screening with a 1280 FDA-approved drug library. We used two Gram positive (Enterococcus faecium P5014 and Staphylococcus aureus P1943) and six Gram negative (Acinetobacter baumannii P1887, Klebsiella pneumoniae P9495, Pseudomonas aeruginosa P6540, Burkholderia multivorans P6539, Pandoraea nosoerga P8103, and Escherichia coli DSM105182 as the reference and control strain). The selected MDR strain panel carried resistance genes or displayed phenotypic resistance to last-line therapies such as carbapenems, vancomycin, or colistin. A total of 107 compounds from nine therapeutic classes inhibited >90% of the growth of the selected Gram negative and Gram positive bacteria at a drug concentration set at 10 µmol/L, and 7.5% were anticancer drugs. The common hit was the antiseptic chlorhexidine. The activity of niclosamide, carmofur, and auranofin was found against the selected methicillin-resistant S. aureus. Zidovudine was effective against colistin-resistant E. coli and carbapenem-resistant K. pneumoniae. Trifluridine, an antiviral, was effective against E. faecium. Deferoxamine mesylate inhibited the growth of XDR P. nosoerga. Drug repurposing by an in vitro screening of a drug library is a promising approach to identify effective drugs for specific bacteria.

A NAG-Guided Nano-Delivery System for Redox- and pH-Triggered Intracellularly Sequential Drug Release in Cancer Cells

Aim

Sequential treatment with paclitaxel (PTXL) and gemcitabine (GEM) is considered clinically beneficial for non-small-cell lung cancer. This study aimed to investigate the effectiveness of a nano-system capable of sequential release of PTXL and GEM within cancer cells.

Methods

PTXL-ss-poly(6-O-methacryloyl-d-galactopyranose)-GEM (PTXL-ss-PMAGP-GEM) was designed by conjugating PMAGP with PTXL via disulfide bonds (-ss-), while GEM via succinic anhydride (PTXL:GEM=1:3). An amphiphilic block copolymer N-acetyl-d-glucosamine(NAG)-poly(styrene-alt-maleic anhydride)₅₈-b-polystyrene₁₃₀ acted as a targeting moiety and emulsifier in formation of nanostructures (NLCs).

Results

The PTXL-ss-PMAGP-GEM/NAG NLCs (119.6 nm) provided a sequential in vitro release of, first PTXL (redox-triggered), then GEM (pH-triggered). The redox- and pH-sensitive NLCs readily distributed homogenously in the cytoplasm. NAG augmented the uptake of NLCs by the cancer cells and tumor accumulation. PTXL-ss-PMAGP-GEM/NAG NLCs exhibited synergistic cytotoxicity in vitro and strongest antitumor effects in tumor-bearing mice compared to NLCs lacking pH/redox sensitivities or free drug combination.

Conclusion

This study demonstrated the abilities of PTXL-ss-PMAGP-GEM/NAG NLCs to achieve synergistic antitumor effect by targeted intracellularly sequential drug release.

Population Pharmacokinetics of Gemcitabine and dFdU in Pancreatic Cancer Patients Using an Optimal Design, Sparse Sampling Approach

BACKGROUND

Gemcitabine remains a pillar in pancreatic cancer treatment. However, toxicities are frequently observed. Dose adjustment based on therapeutic drug monitoring might help decrease the occurrence of toxicities. In this context, this work aims at describing the pharmacokinetics (PK) of gemcitabine and its metabolite dFdU in pancreatic cancer patients and at identifying the main sources of their PK variability using a population PK approach, despite a sparse sampled-population and heterogeneous administration and sampling protocols.

METHODS

Data from 38 patients were included in the analysis. The 3 optimal sampling times were determined using KineticPro and the population PK analysis was performed on Monolix. Available patient characteristics, including cytidine deaminase (CDA) status, were tested as covariates. Correlation between PK parameters and occurrence of severe hematological toxicities was also investigated.

RESULTS

A two-compartment model best fitted the gemcitabine and dFdU PK data (volume of distribution and clearance for gemcitabine: V1 = 45 L and CL1 = 4.03 L/min; for dFdU: V2 = 36 L and CL2 = 0.226 L/min). Renal function was found to influence gemcitabine clearance, and body surface area to impact the volume of distribution of dFdU. However, neither CDA status nor the occurrence of toxicities was correlated to PK parameters.

CONCLUSIONS

Despite sparse sampling and heterogeneous administration and sampling protocols, population and individual PK parameters of gemcitabine and dFdU were successfully estimated using Monolix population PK software. The estimated parameters were consistent with previously published results. Surprisingly, CDA activity did not influence gemcitabine PK, which was explained by the absence of CDA-deficient patients enrolled in the study. This work suggests that even sparse data are valuable to estimate population and individual PK parameters in patients, which will be usable to individualize the dose for an optimized benefit to risk ratio.

Rapid Homogeneous Immunoassay to Quantify Gemcitabine in Plasma for Therapeutic Drug Monitoring

BACKGROUND

Gemcitabine (2',2'-difluoro-2'-deoxycytidine) is a nucleoside analog used as a single agent and in combination regimens for the treatment of a variety of solid tumors. Several studies have shown a relationship between gemcitabine peak plasma concentration (Cmax) and hematological toxicity. An immunoassay for gemcitabine in plasma was developed and validated to facilitate therapeutic drug monitoring (TDM) by providing an economical, robust method for automated chemistry analyzers.

METHODS

A monoclonal antibody was coated on nanoparticles to develop a homogenous agglutination inhibition assay. To prevent ex vivo degradation of gemcitabine in blood, tetrahydrouridine was used as a sample stabilizer. Validation was conducted for precision, recovery, cross-reactivity, and linearity on a Beckman Coulter AU480. Verification was performed on an AU5800 in a hospital laboratory. A method comparison was performed with (LC-MS/MS) liquid chromatography tandem mass spectrometry using clinical samples. Selectivity was demonstrated by testing cross-reactivity of the major metabolite, 2',2'-difluorodeoxyuridine.

RESULTS

Coefficients of variation for repeatability and within-laboratory precision were <8%. The deviation between measured and assigned values was <3%. Linear range was from 0.40 to 33.02 μ/mL (1.5-125.5 μM). Correlation with validated LC-MS/MS methods was R = 0.977. The assay was specific for gemcitabine: there was no cross-reactivity to 2',2'-difluorodeoxyuridine, chemotherapeutics, concomitant, or common medications tested. Tetrahydrouridine was packaged in single-use syringes. Gemcitabine stability in whole blood was extended to 8 hours (at room temperature) and in plasma to 8 days (2-8°C).

CONCLUSIONS

The assay demonstrated the selectivity, test range, precision, and linearity to perform reliable measurements of gemcitabine in plasma. The addition of stabilizer improved the sample handling. Using general clinical chemistry analyzers, gemcitabine could be measured for TDM.

Tumor-targeted polymeric nanostructured lipid carriers with precise ratiometric control over dual-drug loading for combination therapy in non-small-cell lung cancer

Gemcitabine (GEM) and paclitaxel (PTX) are effective combination anticancer agents against non-small-cell lung cancer (NSCLC). At the present time, a main challenge of combination treatment is the precision of control that will maximize the combined effects. Here, we report a novel method to load GEM (hydrophilic) and PTX (hydrophobic) into simplex tumor-targeted nanostructured lipid carriers (NLCs) for accurate control of the ratio of the two drugs. We covalently preconjugated the dual drugs through a hydrolyzable ester linker to form drug conjugates. N-acetyl-d-glucosamine (NAG) is a glucose receptor-targeting ligand. We added NAG to the formation of NAG-NLCs. In general, synthesis of poly(6-O-methacryloyl-d-galactopyranose)–GEM/PTX (PMAGP-GEM/PTX) conjugates was demonstrated, and NAG-NLCs were prepared using emulsification and solvent evaporation. NAG-NLCs displayed sphericity with an average diameter of 120.3±1.3 nm, a low polydispersity index of 0.233±0.04, and accurate ratiometric control over the two drugs. A cytotoxicity assay showed that the NAG-NLCs had better antitumor activity on NSCLC cells than normal cells. There was an optimal ratio of the two drugs, exhibiting the best cytotoxicity and combinatorial effects among all the formulations we tested. In comparison with both the free-drug combinations and separately nanopackaged drug conjugates, PMAGP-GEM/PTX NAG-NLCs (3:1) exhibited superior synergism. Flow cytometry and confocal laser scanning microscopy showed that NAG-NLCs exhibited higher uptake efficiency in A549 cells via glucose receptor-mediated endocytosis. This combinatorial delivery system settles problems with ratiometric coloading of hydrophilic and hydrophobic drugs for tumor-targeted combination therapy to achieve maximal anticancer efficacy in NSCLC.

PK/TD modeling for prediction of the effects of 8C2, an anti-topotecan mAb, on topotecan-induced toxicity in mice

To facilitate the development of an inverse targeting strategy, where anti-topotecan antibodies are administered to prevent systemic toxicity following intraperitoneal topotecan, a pharmacokinetic/toxicodynamic (PK/TD) model was developed and evaluated. The pharmacokinetics of 8C2, a monoclonal anti-topotecan antibody, were assessed following IV and SC administration, and the data were characterized using a two compartmental model with nonlinear absorption and elimination. A hybrid PK model was constructed by combining a PBPK model for topotecan with the two-compartment model for 8C2, and the model was employed to predict the disposition of topotecan, 8C2, and the topotecan-8C2 complex. The model was linked to a toxicodynamic model for topotecan-induced weight-loss, and simulations were conducted to predict the effects of 8C2 on the toxicity of topotecan in mice. Increasing the molar dose ratio of 8C2 to topotecan resulted in a dose-dependent decrease in the unbound (i.e., not bound to 8C2) topotecan exposure in plasma (AUCf) and a decrease in the extent of topotecan-induced weight-loss. Consistent with model predictions, toxicodynamic experiments showed substantial reduction in the percent nadir weight loss observed with 30 mg/kg IP topotecan after co-administration of 8C2 (20 ± 8% vs. 10 ± 8%). The investigation supports the use of anti-topotecan mAb to reduce the systemic toxicity of IP topotecan chemotherapy.

PR-104 a bioreductive pre-prodrug combined with gemcitabine or docetaxel in a phase Ib study of patients with advanced solid tumours

Background

The purpose of this phase Ib clinical trial was to determine the maximum tolerated dose (MTD) of PR-104 a bioreductive pre-prodrug given in combination with gemcitabine or docetaxel in patients with advanced solid tumours.

Methods

PR-104 was administered as a one-hour intravenous infusion combined with docetaxel 60 to 75 mg/m² on day one given with or without granulocyte colony stimulating factor (G-CSF) on day two or administrated with gemcitabine 800 mg/m² on days one and eight, of a 21-day treatment cycle. Patients were assigned to one of ten PR-104 dose-levels ranging from 140 to 1100 mg/m² and to one of four combination groups. Pharmacokinetic studies were scheduled for cycle one day one and ¹⁸F fluoromisonidazole (FMISO) positron emission tomography hypoxia imaging at baseline and after two treatment cycles.

Results

Forty two patients (23 females and 19 males) were enrolled with ages ranging from 27 to 85 years and a wide range of advanced solid tumours. The MTD of PR-104 was 140 mg/m² when combined with gemcitabine, 200 mg/m² when combined with docetaxel 60 mg/m², 770 mg/m² when combined with docetaxel 60 mg/m² plus G-CSF and ≥770 mg/m² when combined with docetaxel 75 mg/m² plus G-CSF. Dose-limiting toxicity (DLT) across all four combination settings included thrombocytopenia, neutropenic fever and fatigue. Other common grade three or four toxicities included neutropenia, anaemia and leukopenia. Four patients had partial tumour response. Eleven of 17 patients undergoing FMISO scans showed tumour hypoxia at baseline. Plasma pharmacokinetics of PR-104, its metabolites (alcohol PR-104A, glucuronide PR-104G, hydroxylamine PR-104H, amine PR-104M and semi-mustard PR-104S1), docetaxel and gemcitabine were similar to that of their single agents.

Conclusions

Combination of PR-104 with docetaxel or gemcitabine caused dose-limiting and severe myelotoxicity, but prophylactic G-CSF allowed PR-104 dose escalation with docetaxel. Dose-limiting thrombocytopenia prohibited further evaluation of the PR104-gemcitabine combination. A recommended dose was identified for phase II trials of PR-104 of 770 mg/m² combined with docetaxel 60 to 75 mg/m² both given on day one of a 21-day treatment cycle supported by prophylactic G-CSF (NCT00459836).

Neutrophil dynamics after chemotherapy and G-CSF: the role of pharmacokinetics in shaping the response

Chemotherapy has profound effects on the hematopoietic system, most notably leading to neutropenia. Granulocyte colony stimulating factor (G-CSF) is often used to deal with this neutropenia, but the response is highly variable. In this paper we examine the role of pharmacokinetics and delivery protocols in shaping the neutrophil responses to chemotherapy and G-CSF. Neutrophil responses to different protocols of chemotherapy administration with varying dosages, infusion times, and schedules are studied through a mathematical model. We find that a single dose of chemotherapy produces a damped oscillation in neutrophil levels, and short-term applications of chemotherapy can induce permanent oscillations in neutrophil level if there is a bistability in the system. In addition, we confirm previous findings [Zhuge et al., J. Theor. Biol., 293(2012), 111-120] that when periodic chemotherapy is given, there is a significant period of delivery that induces resonance in the system and exacerbates the corresponding neutropenia. The width of this resonant period peak increases with the recovery rate after a single chemotherapy, which is given by the real part of the dominant eigenvalue pair at the steady state, and both are determined by a single cooperativity coefficient in the feedback function for the neutrophils. Our numerical studies show that the neutropenia caused by chemotherapy can be overcome if G-CSF is given early after chemotherapy but can actually be worsened if G-CSF is given later, consistent with results reported in Zhuge et al. (2012). The nadir in neutrophil level is found to be more sensitive to the dosage of chemotherapy than that of the G-CSF. Furthermore, dependence of our results with changes in key pharmacokinetic parameters as well as initial functions are studied. Thus, this study illuminates the potential for destructive resonance leading to neutropenia in response to periodic chemotherapy, and explores and explains why the timing of G-CSF is so crucial for successful reversal of chemotherapy induced neutropenia.

The human immunodeficiency virus protease inhibitor ritonavir inhibits lung cancer cells, in part, by inhibition of survivin

INTRODUCTION

Ritonavir is a potential therapeutic agent in lung cancer, but its targets in lung adenocarcinoma are unknown, as are candidate biomarkers for its activity.

METHODS

RNAi was used to identify genes whose expression affects ritonavir sensitivity. Synergy between ritonavir, gemcitabine, and cisplatin was tested by isobologram analysis.

RESULTS

Ritonavir inhibits growth of K-ras mutant lung adenocarcinoma lines A549, H522, H23, and K-ras wild-type line H838. Ritonavir causes G0/G1 arrest and apoptosis. Associated with G0/G1 arrest, ritonavir down-regulates cyclin-dependent kinases, cyclin D1, and retinoblastoma protein phosphorylation. Associated with induction of apoptosis, ritonavir reduces survivin messenger RNA and protein levels more than twofold. Ritonavir inhibits phosphorylation of c-Src and signal transducer and activator of transcription protein 3, which are important events for survivin gene expression and cell growth, and induces cleavage of PARP1. Although knock down of survivin, c-Src, or signal transducer and activator of transcription protein 3 inhibits cell growth, only survivin knock down enhances ritonavir inhibition of growth and survivin overexpression promotes ritonavir resistance. Ritonavir was tested in combination with gemcitabine or cisplatin, exhibiting synergistic and additive effects, respectively. The combination of ritonavir/gemcitabine/cisplatin is synergistic in the A549 line and additive in the H522 line, at clinically feasible ritonavir concentrations (<10 μM).

CONCLUSIONS

Ritonavir is of interest for lung adenocarcinoma therapeutics, and survivin is an important target and potential biomarker for its sensitivity. Ritonavir cooperation with gemcitabine/cisplatin might be explained by involvement of PARP1 in repair of cisplatin-mediated DNA damage and survivin in repair of gemcitabine-mediated double-stranded DNA breaks.

Equilibrative nucleoside transporter 1 genotype, cytidine deaminase activity and age predict gemcitabine plasma clearance in patients with solid tumours

AIM

Gemcitabine (GEM) enters normal and tumour cells via concentrative (CNT) and equilibrative nucleoside transporters (ENT) and is subsequently deaminated to the inactive difluorodeoxyurine (dFdU) by cytidine deaminase (CDA). The aim of our study was to ascertain whether the nucleoside transporter genotype and the CDA activity phenotype can predict total GEM plasma clearance.

METHODS

Forty-seven patients received GEM 1000-1250mgm(-2) i.v. over 30min. Plasma concentrations of GEM and dFdU were measured and individual pharmacokinetic profiles were determined. CDA activity was measured ex vivo in plasma samples. The two most common hENT1 and hCNT1 polymorphisms were determined from genomic DNA.

RESULTS

Multivariate analysis revealed that GEM plasma clearance (CL) was positively correlated with the end of infusion dFdU : GEM ratio (P < 0.0001), which is a marker of in vivo CDA activity. The ENT1 genotype characterized by high transport capacity (G/G) and age were inversely correlated with CL (P= 0.027 and 0.048, respectively). A strong correlation was found between end of infusion GEM concentration and area under the concentration-time curve from time 0 to infinity (AUC(0,∞)) (r(2) = 0.77).

CONCLUSIONS

Our results confirm the role of CDA and age on the interindividual variability of GEM CL and show the contribution of the hENT1 genotype for the first time.

A phase I study of the combination of intravenous reovirus type 3 Dearing and gemcitabine in patients with advanced cancer

PURPOSE

This study combined systemic administration of the oncolytic reovirus type 3 Dearing (reovirus) with chemotherapy in human subjects. We aimed to determine the safety and feasibility of combining reovirus administration with gemcitabine and to describe the effects of gemcitabine on the antireoviral immune response.

EXPERIMENTAL DESIGN

Patients received reovirus in various doses, initially we dosed for five consecutive days but this was poorly tolerated. We amended the protocol to administer a single dose and administered up to 3 × 10(10) TCID(50). Toxicity was assessed by monitoring of clinical and laboratory measurements. We assessed antibody response by cytotoxicity neutralization assay.

RESULTS

Sixteen patients received 47 cycles of reovirus. The two initial patients and one patient in the final cohort experienced dose limiting toxicity (DLT). The DLTs consisted of two asymptomatic grade 3 liver enzyme rises and one asymptomatic grade 3 troponin I rise. Common toxicities consisted of known reovirus and gemcitabine associated side effects. Further analysis showed a potential interaction between reovirus and gemcitabine in causing liver enzyme rises. Grade 3 rises in liver enzymes were associated with concomitant aminocetophen use. Importantly, the duration of the liver enzyme rise was short and reversible. Neutralizing antibody responses to reovirus were attenuated both in time-to-occurrence and peak height of the response.

CONCLUSIONS

Reovirus at the dose of 1 × 10(10) TCID(50) can be safely combined with full dose gemcitabine. Combination of reovirus with gemcitabine affects the neutralizing antibody response and this could impact both safety and efficacy of this treatment schedule.

A dose escalation and pharmacokinetic study of the biweekly administration of paclitaxel, gemcitabine and oxaliplatin in patients with advanced solid tumors

PURPOSE

To determine the dose-limiting toxicities (DLTs) and the maximum tolerated doses (MTDs) of the paclitaxel, gemcitabine, oxaliplatin combination administered biweekly in patients with advanced solid tumors.

PATIENTS AND METHODS

Patients received escalated doses of paclitaxel (starting dose: 100 mg/m(2)), gemcitabine (starting dose: 800 mg/m(2)) and oxaliplatin (starting dose: 50 mg/m(2)) on days 1 and 15 in cycles of every 4 weeks. DLTs were evaluated during the first cycle.

RESULTS

Twenty-seven patients (median age 65 years) with performance status 0-1 were treated on six dose escalation levels. Eleven patients (40.7%) were chemotherapy naïve, six (22.2%) had received 1 prior chemotherapy regimen and ten (37.1%) 2 or more. The DLT level was reached at the doses of paclitaxel 110 mg/m(2), gemcitabine 1,150 mg/m(2) and LOHP 70 mg/m(2). The dose-limiting events were grade 4 neutropenia and grade 3 febrile neutropenia. Neutropenia was the most common adverse event. A median of 3 cycles per patient was administered. One complete and five partial responses were observed in patients with ovarian carcinoma, NSCLC, urothelial cancer, mesothelioma and cancer of unknown primary. No pharmacokinetic drug interactions were detected.

CONCLUSIONS

The recommended doses for future phase II studies of this combination are paclitaxel 110 mg/m(2), gemcitabine 1,000 mg/m(2) and oxaliplatin 70 mg/m(2) every 2 weeks. The regimen is generally well tolerated and merits further evaluation.

Phase I trial of nanoparticle albumin-bound paclitaxel in combination with gemcitabine in patients with thoracic malignancies

BACKGROUND

Nab-paclitaxel has a different toxicity profile than solvent-based paclitaxel including a lower rate of severe neutropenia. This trial was designed to determine the maximum tolerated dose and dose limiting toxicities (DLT) of nab-paclitaxel in combination with gemcitabine.

METHODS

Patients were required to have a performance status of 0 to 1, < or = three prior cytotoxic chemotherapy regimens, and preserved renal, hepatic, and bone marrow function. Patients received gemcitabine 1000 mg/m on days 1, 8 in all cohorts, and nab-paclitaxel at doses of 260, 300, 340 mg/m every 21 days depending on the treatment cohort (1 cycle = 21 days). DLT were assessed after the first cycle, and doses were escalated in cohorts of 3 to 6 patients.

RESULTS

Eighteen patients were consented and 15 patients are evaluable [median age 62 years (range, 35-75); median number of prior treatments 3 (range, 1-4); tumor types: non-small cell lung cancer (NSCLC) (n = 8), small cell lung cancer (SCLC) (n = 6), and esophageal cancer (n = 1)]. At a nab-paclitaxel dose of 300 mg/m, 1 of 6 pts experienced a DLT (omission of day 8 gemcitabine due to absolute neutrophil count < 500), and at an nab-paclitaxel dose of 340 mg/m 2 of 3 patients experienced a DLT (1 pt grade 3 rash and pruritus; 1 pt grade 3 fatigue and anorexia). Responses were observed in NSCLC and SCLC.

CONCLUSIONS

The maximum tolerated dose of nab-paclitaxel is 300 mg/m in combination with gemcitabine 1000 mg/m on days 1, 8 every 21 days. This combination demonstrated activity in previously treated NSCLC and SCLC patients.

A phase I pharmacokinetic study of hypoxic abdominal stop-flow perfusion with gemcitabine in patients with advanced pancreatic cancer and refractory malignant ascites

PURPOSE

As no curative treatment for advanced pancreatic and biliary cancer with malignant ascites exists, new modalities possibly improving the response to available chemotherapies must be explored. This phase I study assesses the feasibility, tolerability and pharmacokinetics of a regional treatment of gemcitabine administered in escalating doses by the stop-flow approach to patients with advanced abdominal malignancies (adenocarcinoma of the pancreas, n = 8, and cholangiocarcinoma of the liver, n = 1).

EXPERIMENTAL DESIGN

Gemcitabine at 500, 750 and 1,125 mg/m(2) was administered to three patients at each dose level by loco-regional chemotherapy, using hypoxic abdominal stop-flow perfusion. This was achieved by an aorto-caval occlusion by balloon catheters connected to an extracorporeal circuit. Gemcitabine and its main metabolite 2',2'-difluorodeoxyuridine (dFdU) concentrations were measured by high performance liquid chromatography with UV detection in the extracorporeal circuit during the 20 min of stop-flow perfusion, and in peripheral plasma for 420 min. Blood gases were monitored during the stop-flow perfusion and hypoxia was considered stringent if two of the following endpoints were met: pH </= 7.2, pO(2) nadir ratio </=0.70 or pCO(2) peak ratio >/=1.35. The tolerability of this procedure was also assessed.

RESULTS

Stringent hypoxia was achieved in four patients. Very high levels of gemcitabine were rapidly reached in the extracorporeal circuit during the 20 min of stop-flow perfusion, with C (max) levels in the abdominal circuit of 246 (+/-37%), 2,039 (+/-77%) and 4,780 (+/-7.3%) mug/ml for the three dose levels 500, 750 and 1,125 mg/m(2), respectively. These C (max) were between 13 (+/-51%) and 290 (+/-12%) times higher than those measured in the peripheral plasma. Similarly, the abdominal exposure to gemcitabine, calculated as AUC(t0-20), was between 5.5 (+/-43%) and 200 (+/-66%)-fold higher than the systemic exposure. Loco-regional exposure to gemcitabine was statistically higher in presence of stringent hypoxia (P < 0.01 for C (max) and AUC(t0-20), both normalised to the gemcitabine dose). Toxicities were acceptable considering the complexity of the procedure and were mostly hepatic; it was not possible to differentiate the respective contributions of systemic and regional exposures. A significant correlation (P < 0.05) was found between systemic C (max) of gemcitabine and the nadir of both leucocytes and neutrophils.

CONCLUSIONS

Regional exposure to gemcitabine-the current standard drug for advanced adenocarcinoma of the pancreas-can be markedly enhanced using an optimised hypoxic stop-flow perfusion technique, with acceptable toxicities up to a dose of 1,125 mg/m(2). However, the activity of gemcitabine under hypoxic conditions is not as firmly established as that of other drugs such as mitomycin C, melphalan or tirapazamine. Further studies of this investigational modality, but with bioreductive drugs, are therefore warranted first to evaluate the tolerance in a phase I study and later on to assess whether it does improve the response to chemotherapy.

Intra-patient alternated dose escalation of paclitaxel and gemcitabine versus paclitaxel followed by fixed dose rate infusion of gemcitabine in fit elderly non-small cell lung cancer patients

PURPOSE

This study was undertaken to select the best schedule of administration for the paclitaxel plus gemcitabine combination in fit elderly patients affected by locally advanced or metastatic non-small cell lung cancer (NSCLC).

PATIENTS AND METHODS

Ninety-eight patients in stage III or IV NSCLC, aged 70 years or more and in ECOG performance status (PS)<or=1, were randomly allocated to receive: paclitaxel 80 mg/m(2) plus gemcitabine 1000 mg/m(2) i.v. on days 1 and 8, with an intra-patient alternated dose escalation up to 100 and 1200 mg/m(2), respectively, over three cycles (arm A); or paclitaxel 80 mg/m(2) followed by gemcitabine 1000 mg/m(2) i.v. (100 min) on days 1 and 8 (arm B). Treatment was repeated in both arms every 3 weeks for a maximum of six cycles.

RESULTS

With a median of 3 (range, 1-6) delivered cycles, the two schedules yielded a similar response rate (25% versus 26%), failure-free survival (median, 3.3 months versus 3.2 months), progression-free survival (median, 5.1 months versus 5.2 months), and overall survival (median, 9.7 months versus 9.6 months). Survival was independently affected by the PS of patients and by the metastatic spread. Severe side effects were comparable and negligible in both arms.

CONCLUSION

A substantial difference between these two schedules in terms of efficacy and safety can be ruled-out. Paclitaxel plus gemcitabine is an advisable combination for treating fit elderly patients with advanced NSCLC.

The efficacy and relationship between peak concentration and toxicity profile of fixed-dose-rate gemcitabine plus carboplatin in patients with advanced non-small-cell lung cancer

PURPOSE

To investigate the efficacy and relationship between plasma concentrations at the end of infusion (C(end of infusion)) and toxicity profile of fixed-dose-rate gemcitabine plus carboplatin in chemotherapy-naive patients with advanced non-small-cell lung cancer (NSCLC).

PATIENTS AND METHODS

Patients were given gemcitabine by 120 min infusion [at a fixed dose rate (FDR) of 10 mg/m(2)/min] on days 1 and 8 of a 21-day cycle, immediately followed by carboplatin AUC 5 by 4 h infusion on day 1. C (end of infusion) of gemcitabine was determined by ion-pair reversed-phase high-performance liquid chromatography (HPLC).

RESULTS

By the close-out date, in our study population, the estimated median time to tumor progression (TTP) was 7 months (95% CI 4-10 months), median overall survival (OS) was 12 months (95% CI 11.2-12.8 months). The mean value of C (end of infusion) of 21 eligible patients was 16.48 +/- 8.07 micromol/l (range 27.43-2.87 micromol/l). The main hematological toxicities were transient grade 3-4 thrombocytopenia. The mean percentages of reduction of WBC, NEC, PLTC and Hb of 21 eligible patients were 38.3 +/- 38.1%, 31.3 +/- 73.6%, 31.8 +/- 53.5% and 12.0 +/- 12.2%, respectively. The analysis of the C(end of infusion) of gemcitabine and the percentage of reduction in WBC showed a significant correlation (r(2) = 0.4575; p < 0.05). A significant correlation (r(2) = 0.5671; p < 0.05) was also observed between the percentage of reduction of PLTC and C(end of infusion) of gemcitabine infusion.

CONCLUSION

The clinical data in this trial supports the further evaluation the regimen in advanced NSCLC patients, due to its predictable kinetic behavior and less severe toxicity profile than expected.

Coadministration of oxaliplatin does not influence the pharmacokinetics of gemcitabine

We investigated the possible pharmacokinetic interactions of gemcitabine and oxaliplatin in patients with advanced solid tumors. Ten patients with advanced stage solid tumors were treated with gemcitabine (1500 mg/m) as a 30-min intravenous infusion on days 1 and 8, followed by oxaliplatin (130 mg/m) as a 4-h intravenous infusion, on day 8 every 21 days. Pharmacokinetic data for 24 h after dosing were obtained for both day 1 (gemcitabine without oxaliplatin coadministration) and day 8 (gemcitabine with oxaliplatin) during the first cycle of treatment. Gemcitabine levels in plasma were quantified using a reverse-phase high-performance liquid chromatography assay with ultraviolet detection, and total and ultrafiltrated platinum levels by flameless atomic absorption spectrophotometry with deuterium correction. All pharmacokinetic parameters of gemcitabine seemed to be unchanged when coadministered with oxaliplatin (day 8) compared with pharmacokinetic data of gemcitabine given as a single agent (day 1). The mean (maximum) concentration of gemcitabine on days 1 and 8 was 13.57 (+/-7.42) and 10.23 (+/-5.21) mg/l, respectively (P=0.28), and the mean half-life was 0.32 and 0.44 h, respectively (P=0.40). Similarly, the P-values for AUC0-24 and the observed clearance were 0.61 and 0.30, respectively. Plasma total and free platinum levels were in agreement with other published data. Gemcitabine disposition appeared to be unaffected by oxaliplatin coadministration because no significant changes in pharmacokinetics between day 1 (gemcitabine without oxaliplatin coadministration) and day 8 (gemcitabine with oxaliplatin) were observed.

A proper schedule of weekly paclitaxel and gemcitabine combination is highly active and very well tolerated in NSCLC patients

BACKGROUND

In a previous phase I dose-escalation study, we showed a weekly administration of paclitaxel (TAX) and gemcitabine (GEM) to be active and very well tolerated in non-small-cell lung cancer (NSCLC) patients, with the lack of interaction between drugs. The dose of GEM 1500 mg/m(2) and TAX 100 mg/m(2) was selected for phase II studies due to its predictable kinetic behaviour and less severe thrombocytopenia.

PATIENTS AND METHODS

Fifty-four chemo-naïve patients with advanced NSCLC (53 patients: stage IV) received TAX (100mg/m(2) i.v. infusion over 1h) followed by GEM 1500 mg/m(2) over 30 min) on days 1, 8, 15 and 21 of a 28-day cycle.

RESULTS

The objective response rate was 46% (95% CI 32-61), median OS of 10.4 ms (95% CI 6.5-4.3), and a 1-year survival rate of 53%. Grades 3 and 4 haematological toxicity consisted of non-febrile neutropenia and thrombocytopenia in 13 and 4% of the cycles, respectively. Grade 3 non-haematological toxicities were observed in three patients (asthenia, diarrhoea and neuropathy), and were always reversible.

CONCLUSIONS

This weekly schedule of TAX and GEM is highly active in chemo-naïve NSCLC patients and confirms the low toxicity profile already observed in a previous phase I study.

Pharmacokinetics of gemcitabine and its primary metabolite in dogs after intravenous infusion

Gemcitabine is a relatively new chemotherapeutic compound used to treat a variety of cancers in dogs. Previous work presented in a companion paper explored the plasma kinetics of gemcitabine and its inactive metabolite, 2',2'-difluorodeoxyuridine (dFdU), in dogs after an intravenous bolus gemcitabine dose and demonstrated the saturation of intracellular dFdCTP (2',2'-difluorodeoxycytidine 5'-triphosphate) occurs in vitro with increasing extracellular gemcitabine exposure in canine melanoma cells. In this study, the plasma pharmacokinetics (PKs) of gemcitabine and dFdU are further explored after gemcitabine doses of 10, 30, and 60 mg/kg administered by intravenous infusion with a loading dose. Gemcitabine displayed linear PKs, while the kinetics of dFdU were not dose proportional. The overall clearance, volume of distribution at steady-state, and terminal elimination half-life (t(1/2)) for gemcitabine were 0.421 L/h.kg, 0.822 L/kg, and 1.49 h, respectively. Plasma concentrations of dFdU peaked at approximately 2 h postdosing and had a t(1/2) of 14.9 h.

Pharmacology of the paclitaxel-cisplatin, gemcitabine-cisplatin, and paclitaxel-gemcitabine combinations in patients with advanced non-small cell lung cancer

PURPOSE

To compare the pharmacology of the paclitaxel-cisplatin, gemcitabine-cisplatin and paclitaxel-gemcitabine combinations in patients with advanced non-small cell lung cancer (NSCLC).

PATIENTS AND METHODS

Twenty-four chemo-naive patients with advanced NSCLC were randomized to receive one of the three regimens. Plasma pharmacokinetics and pharmacologic parameters in mononuclear cells were compared and related to toxicity and efficacy.

RESULTS

Pharmacological parameters of gemcitabine and cisplatin were not influenced by the combination with one of the other agents, while the paclitaxel clearance was significantly lower for the combination with cisplatin as compared to gemcitabine (P=0.024). The percentage decrease in platelets was significantly higher for the gemcitabine combinations (P=0.004) and related to the dFdCTP-Cmax (P=0.030). Pharmacologic parameters were not related to response or survival.

CONCLUSIONS

Gemcitabine and cisplatin pharmacology were not influenced by the combination with one of the other agents, while paclitaxel has a lower clearance in combination with cisplatin as compared to gemcitabine.

Population pharmacokinetics of orally administered paclitaxel formulated in Cremophor EL

AIM

The vehicle Cremophor EL (CrEL) has been shown to impair the absorption of paclitaxel by micellar entrapment of the drug in the gastrointestinal tract. The goal of this study was to develop a semimechanistic population pharmacokinetic model to study the influence of CrEL on the oral absorption of paclitaxel.

METHOD

Paclitaxel plasma-concentration time profiles were available from 55 patients (M:F, 17 : 38; total 67 courses; 797 samples), receiving paclitaxel orally once or twice daily (dose range 60-360 mg m(-2)) together with 12-15 mg kg(-1) cyclosporin A. A population pharmacokinetic model was developed using the nonlinear mixed effect modelling program NONMEM.

RESULTS

After absorption, paclitaxel pharmacokinetics were best described using a two-compartment model with linear distribution from the central compartment into a peripheral compartment and first-order elimination. Paclitaxel in the gastrointestinal tract was modelled as free fraction or bound to CrEL, with only the free fraction available for absorption into the central compartment. The equilibrium between free and bound paclitaxel was influenced by the concentration of CrEL present in the gastrointestinal tract. The concentration of CrEL in the gastrointestinal tract decreased with time with a first order rate constant of 1.73 h(-1). The bioavailability of paclitaxel was independent of the dose and of CrEL. Estimated apparent paclitaxel clearance and volume of distribution were 127 l h(-1) and 409 l, respectively. Large interpatient variability was observed. Covariate analysis did not reveal significant relationships with any of the pharmacokinetic parameters.

CONCLUSION

A pharmacokinetic model was developed that described the pharmacokinetics of orally administered paclitaxel. CrEL strongly influenced paclitaxel absorption from the gastrointestinal tract resulting in time-dependent but no significant dose-dependent absorption over the examined dose range studied.

Paclitaxel and Gemcitabine, As First-Line Chemotherapy, Combined with Trastuzumab in Patients with Advanced Breast Cancer: A Phase II Study Conducted by the Hellenic Cooperative Oncology Group (HeCOG)

PURPOSE

Advanced breast cancer (ABC) is an incurable disease. Standard first-line treatment for patients with HER-2/neu overexpressing tumors includes the combination of the humanized monoclonal antibody trastuzumab with chemotherapy, mainly paclitaxel. This combination is the first to demonstrate a survival advantage in this group of patients. To improve on these results, we investigated a triplet, paclitaxel-gemcitabine-trastuzumab (TGH), in a phase II study.

PATIENTS AND METHODS

Patients with ABC were accrued to the study. Treatment consisted of paclitaxel 80 mg/m2/week, gemcitabine 1000 mg/m2 every 2 weeks, and trastuzumab 4 mg/kg loading dose and then 2 mg/kg/week. Patients were treated on study for a total of 12 weeks. Response evaluation was performed at the end of the 12 weeks. Continuation of treatment beyond the 12 weeks was left to the discretion of the investigator. Primary study endpoint was response. Toxicity assessment and survival were secondary endpoints.

RESULTS

Between November 2000 and May 2002, 40 patients were accrued and 32 patients completed all 12 weeks of therapy. One patient died of septic shock during therapy. Grade III and IV neutropenia was seen in 12.5% of cases each. Grade III anemia was seen in two patients, and grade III and IV thrombocytopenia in three and two patients, respectively. Both paclitaxel and gemcitabine were delivered at 86% of the planned dose intensity. Six patients achieved a complete response (CR) and 15 a partial response for an overall response rate of 52.5%. An additional 25% demonstrated stable disease and 20% progressive disease. Median duration of response was 14 months. All six patients who achieved CR are still in CR for 6 to 19 months. After a median follow up of 12.2 months, 19 patients have progressed and 7 have died. Median time to progression is 13.7 months, whereas median survival has not been reached.

CONCLUSION

TGH is a well-tolerated and effective regimen for the first-line treatment of ABC. Randomized comparison between paclitaxel, trastuzumab, and triplets are warranted.

Investigation of the pharmacokinetics of gemcitabine and 2′,2′-difluorodeoxyuridine in human plasma by liquid chromatography

Gemcitabine (2',2'-difluorodeoxycytidine, dFdC) is a difluorine-substituted deoxycytidine analogue that has demonstrated antitumor activity against solid tumors. The pharmacokinetics of dFdC and its metabolite, 2',2'-difluorodeoxyuridine (dFdU) have been studied; however, their disposition has never been evaluated in a patient with bladder cancer. A patient with bladder cancer was treated with dFdC 1000 mg/m(2) over a 30min period. The patient received a dFdC infusion once per week for 3 weeks followed by a rest week. Serial plasma samples were obtained prior to, during, and after completion of the infusion for determination of dFdC and dFdU concentrations. dFdC and dFdU concentrations were measured using normal-phase high-performance liquid chromatography and one-compartment open model methods. Maximum plasma concentrations (C(max)) and area under the plasma concentration-time curve for dFdC and dFdU were 24.5 microg/ml and 11200 microg/Lh, 49.1 microg/ml and 272,800 microg/Lh, respectively.

Role of gemcitabine in the treatment of advanced and metastatic breast cancer

Gemcitabine is an antimetabolite drug with proven antitumor activity and tolerability in metastatic breast cancer. In a total of nine studies, gemcitabine monotherapy has reached response rates of up to 37% in the first-line setting, 26% in the second-line setting, and 18% or better in the third-line setting. Gemcitabine is an excellent choice for combination therapy by its unique mechanism of action and favorable toxicity profile, thus limiting the risk of pretreatment-related drug resistance and overlapping toxicity, and by its potential for synergistic interaction with some combination partners as indicated in preclinical studies. Numerous phase II clinical studies have combined gemcitabine with other active agents such as the taxanes, vinorelbine, vindesine, cisplatin, 5-fluorouracil, as well as anthracyclines across various regimens and conditions of pretreatment. Most of these two-drug combinations have consistently demonstrated higher efficacy than either single agent, particularly in pretreated patients. Even higher efficacy has been obtained with triple-drug regimens including gemcitabine, anthracyclines (epirubicin or doxorubicin), and paclitaxel; these regimens have yielded overall response rates of 58-92% as first-line treatment. In view of these results, gemcitabine may be regarded as a valuable alternative to the palliative treatment of metastatic breast cancer, and an excellent option for the development of effective combination treatment not only in first-line therapy, but also for intensively pretreated patients previously exposed to anthracyclines and/or the taxanes.