Schedule dependent toxicity and efficacy of combined gemcitabine/paclitaxel treatment in mouse adenocarcinoma

Ultrasound Doppler as an Imaging Modality for Selection of Murine 4T1 Breast Tumors for Combination Radiofrequency Hyperthermia and Chemotherapy

Noninvasive radiofrequency-induced (RF) hyperthermia has been shown to increase the perfusion of chemotherapeutics and nanomaterials through cancer tissue in ectopic and orthotopic murine tumor models. Additionally, mild hyperthermia (37°C-45°C) has previously shown a synergistic anticancer effect when used with standard-of-care chemotherapeutics such as gemcitabine and Abraxane. However, RF hyperthermia treatment schedules remain unoptimized, and the mechanisms of action of hyperthermia and how they change when treating various tumor phenotypes are poorly understood. Therefore, pretreatment screening of tumor phenotypes to identify key tumors that are predicted to respond more favorably to hyperthermia will provide useful mechanistic data and may improve therapeutic outcomes. Herein, we identify key biophysical tumor characteristics in order to predict the outcome of combinational RF and chemotherapy treatment. We demonstrate that ultrasound imaging using Doppler mode can be utilized to predict the response of combinational RF and chemotherapeutic therapy in a murine 4T1 breast cancer model.

Chemotherapy and Radiofrequency-Induced Mild Hyperthermia Combined Treatment of Orthotopic Pancreatic Ductal Adenocarcinoma Xenografts

Patients with pancreatic ductal adenocarcinomas (PDAC) have one of the poorest survival rates of all cancers. The main reason for this is related to the unique tumor stroma and poor vascularization of PDAC. As a consequence, chemotherapeutic drugs, such as nab-paclitaxel and gemcitabine, cannot efficiently penetrate into the tumor tissue. Non-invasive radiofrequency (RF) mild hyperthermia treatment was proposed as a synergistic therapy to enhance drug uptake into the tumor by increasing tumor vascular inflow and perfusion, thus, increasing the effect of chemotherapy. RF-induced hyperthermia is a safer and non-invasive technique of tumor heating compared to conventional contact heating procedures. In this study, we investigated the short- and long-term effects (~20 days and 65 days, respectively) of combination chemotherapy and RF hyperthermia in an orthotopic PDAC model in mice. The benefit of nab-paclitaxel and gemcitabine treatment was confirmed in mice; however, the effect of treatment was statistically insignificant in comparison to saline treated mice during long-term observation. The benefit of RF was minimal in the short-term and completely insignificant during long-term observation.

In Vivo Evaluation of the Anticancer Activity of the Gemcitabine and Doxorubicin Combined in a Nanoemulsion

Context

Doxorubicin (DOX) and gemcitabine (GEM) are anticancer drugs that were combined in a nanoemulsion (NE) to reduce their adverse side effects.

Aim

To detect the antitumor activity of the combination formulas of GEM and DOX, loaded either in water (GEM+DOX-Sol) or in NEs (GEM-DOX combination/loaded NE [GEM+DOX/LNE]), in female Swiss albino mice inoculated with Ehrlich ascites carcinoma (EAC).

Settings and Design

The anticancer assessment of the NE formulas was implemented in 200 mice, which were divided into 10 groups.

Materials and Methods

It includes the detection of the change in body weight, analysis of the hematological and serum biochemical profiles, and study of the histopathologic alterations of the heart tissues.

Statistical Analysis

One-factor analysis of variance was used.

Results

Mice treated with GEM + DOX/LNE, which have an z-average of 155.38±2.33nm and zeta potential of -38.5±1.3 mV, recorded a considerable improvement in the mean survival time (MST), which was 60 days, as compared to the EAC control group, which has an MST of 28 days. It also restored the hematological and serum biochemical parameters toward normal values.

Conclusions

The combination of GEM and DOX in NE has significantly diminished the cardiotoxicity of DOX and hematotoxicity of GEM while improving their antitumor properties.

Synergy of Irofulven in combination with various anti-metabolites, enzyme inhibitors, and miscellaneous agents in MV522 lung carcinoma cells: marked interaction with gemcitabine and 5-fluorouracil

The novel agent Irofulven (HMAF, NSC 683863) has demonstrated significant antitumor activity against solid tumors in various xenograft models and human clinical trials. The antitumor potential of combining irofulven with 72 different anti-metabolite, enzyme inhibiting, and miscellaneous agents was investigated in this study. The human lung carcinoma MV522 cell line and its corresponding xenograft model were used to evaluate the activity of irofulven in combination with these different agents. Irofulven in combination with select anti-metabolites, notably cytidine or adenine-derived agents, displayed strong synergistic activity in both in vitro and in vivo studies. Agents demonstrating strong synergistic interaction with irofulven included gemcitabine, cyclocytidine, cytarabine, fludarabine phosphate, cladribine, and 5-fluorouracil. Other anti-metabolites, enzyme inhibitors, and a variety of miscellaneous agents failed to interact beneficially when administered in combination with irofulven. The therapeutic activity of irofulven is enhanced considerably when irofulven is combined with select anti-metabolite agents, and further clinical evaluation of these combinations is warranted. The synergistic interaction with these combinations may stem from a variety of actions including inhibition of the nucleotide excision repair (NER) pathway, topoisomerase I activity, and caspase-dependent and independent induction of apoptosis.

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.

Microregional effects of gemcitabine in HCT-116 xenografts

To examine the tumor microregional effects after gemcitabine administration to mice, we mapped the location of proliferating and hypoxic cells relative to vasculature in human colon cancer xenografts. The S-phase marker bromodeoxyuridine was used as a surrogate of drug effect and administered 2 hours before tumor excision, whereas vessel position and perfusion were assessed via staining for CD31 and intravenous injection of carbocyanine, respectively. Hypoxia was detected using pimonidazole. Images of the four markers were overlaid to reveal the spatial relationship between proliferation, vasculature, and hypoxia and to examine the microregional effects. Within 1 day after administration of 240 mg/kg of gemcitabine, proliferation throughout the tumor was completely inhibited. Over time, a reemergence of dividing cells occurred in relation to the distance from vasculature. Microregional analysis revealed that cells located distal to vasculature commenced cycling sooner than cells located proximal to vasculature. A similar trend was seen after multiple doses of gemcitabine (40 mg/kg on days 1, 4, 7, and 10). The possibility that the effect of gemcitabine could be attributed to changes in oxygenation was discounted after examining the vessel perfusion and patterns of hypoxia. The effect of gemcitabine was examined in multilayered cell culture, and at doses <30 micromol/L, a gradient in proliferation between the exposed and unexposed sides was observed. We show a differential effect on cell proliferation in relation to vasculature and conclude that cells distal to blood vessels are less affected by gemcitabine probably because of limited penetration.

Biweekly paclitaxel plus gemcitabine in advanced breast cancer: phase II trial and predictive value of HER2 extracellular domain

BACKGROUND

We wanted to assess the toxicity and efficacy of paclitaxel plus gemcitabine in advanced breast cancer and to confirm whether circulating HER2 extracellular domain (ECD) correlates with treatment response.

PATIENTS AND METHODS

Forty-three patients received paclitaxel 150 mg/m2 followed by gemcitabine 2500 mg/m2, both on day 1 of 14-day cycles, with a maximum of eight cycles. Serum levels of HER2 ECD were assessed by ELISA.

RESULTS

All patients were evaluable for toxicity and 42 for efficacy. Overall toxicity was low. Grade 3 neutropenia occurred in 12% of patients and grade 4 in 17%, and other grade 3 toxicities in <5%. One patient had an allergic infusion reaction. Overall response rate was 71% [95% confidence interval (CI) 62% to 81%], with 11 patients achieving a complete response (26%). With a median follow-up of 26 months, the median time to progression was 16.6 months. Response rate correlated significantly with HER2 ECD, with 42% of HER2 ECD-positive patients responding versus 83% of HER2 ECD-negative patients (P = 0.02). Furthermore, response duration was shorter in patients with positive HER2 ECD levels (7.9 versus 14.4 months; P = 0.04).

CONCLUSIONS

Paclitaxel plus gemcitabine given as an every 2-weeks schedule is a well tolerated and active regimen in advanced breast carcinoma. This is an attractive combination to use when anthracyclines are not indicated, such as in HER2 positive cases that receive trastuzumab. In addition, elevated levels of HER2 ECD adversely affect the efficacy of treatment.

Combination chemotherapy of the taxanes and antimetabolites: its use and limitations

In an effort to improve response rates of chemotherapy, taxanes have been combined with other cytotoxic agents such as antimetabolites. However, the use of some of these combinations in patients has been restricted by severe toxicity. The significance of the sequence of drug administration in combining methotrexate (MTX) and taxanes was recognised in in vitro studies, showing synergistic effects for the sequence of MTX followed by paclitaxel, and antagonism for exposure in the reverse order. A possible explanation might be an MTX-induced synchronisation of cells in the S phase of the cell cycle, after which cells are more susceptible for the cytotoxic action of taxanes. Clinical studies using this sequence were hampered by severe neutropenia and mucositis at relatively low doses of both drugs. As no pharmacokinetic interactions were observed, the excess of toxicity may have been due to sequence-dependent synergistic actions on bone marrow and mucosa. In contrast, and confusingly, in vitro studies on 5-fluorouracil (5-FU) and taxanes indicate that 5-FU preceeding or simultaneously given to paclitaxel impairs cytotoxicity as compared with paclitaxel monotherapy, while the reverse sequence results in additive or synergistic cytotoxicity. While almost all clinical studies have used the sequence of a taxane followed by 5-FU, various schedules appeared feasible and effective. The combination of a 5-FU analogue, capecitabine and taxanes was supported by in vitro data. A large phase III trial confirmed the feasibility and superior efficacy of this combination in breast cancer patients relapsing after an anthracycline. Conflicting results exist on the benefit of combining gemcitabine and taxanes in tumour cell lines. Although the accumulation of gemcitabine triphosphate (dFdCTP) in mononuclear cells was significantly higher with an increasing dose of paclitaxel, no pharmacokinetic interactions for both agents were noticed. A pharmacokinetic analysis of the gemcitabine-docetaxel combination therapy has not been published in detail. Despite numerous trials, so far no optimum schedule has been established. Regarding data on actually delivered dose intensities, a 2- or 3-weekly cycle seems favourable and feasible. However, possible severe pulmonary toxicity warrants cautious monitoring of patients treated with this combination. Different outcomes of preclinical and clinical studies reveal that combining two chemotherapeutic agents is not simply a matter of putting antitumour activities together. Drug interaction may result in synergism, not only of efficacy but also of toxic side-effects. Adding two drugs may also implicate antagonism in drug efficacy due to unwanted interference in cytotoxicity or pharmacokinetics. For agents acting at a specific phase of the cell cycle, the sequence of administration may determine the efficacy and toxicity of a combination therapy. Because of an observed discrepancy between in vitro data and clinical studies, we would like to emphasise the need for adequate dose-finding clinical trials together with pharmacokinetic data analysis before examining any new combination chemotherapy in more detail in phase II studies.

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

BACKGROUND

Gemcitabine and paclitaxel are two of the most active agents in non-small-cell lung cancer (NSCLC), and pharmacologic investigation of the combination regimens including these drugs may offer a valuable opportunity in treatment optimization. The present study investigates the pharmacokinetics and pharmacodynamics of paclitaxel and gemcitabine in chemotherapy-naive patients with advanced NSCLC within a phase I study.

PATIENTS AND METHODS

Patients were given i.v. paclitaxel 100 mg/m2 by one-hour infusion followed by gemcitabine 1,500, 1,750 and 2,000 mg/m2 by 30-min administration. Plasma levels of paclitaxel, gemcitabine and its metabolite 2',2'-difluorodeoxyuridine (dFdU) were determined by high-performance liquid chromatography (HPLC). Concentration-time curves were modeled by compartmental and non-compartmental methods and pharmacokinetic/pharmacodynamic (PK/PD) relationships were fitted according to a sigmoid maximum effect (Emax) model.

RESULTS

Paclitaxel pharmacokinetics did not change as a result of dosage escalation of gemcitabine from 1,500 to 2,000 mg/m2. A nonproportional increase in gemcitabine peak plasma levels (Cmax, from 18.56 +/- 4.94 to 40.85 +/- 14.85 microg/ml) and area under the plasma concentration-time curve (AUC, from 9.99 +/- 2.75 to 25.01 +/- 9.87 h x microg/ml) at 1,500 and 2,000 mg/m, respectively, was observed, suggesting the occurrence of saturation kinetics at higher doses. A significant relationship between neutropenia and time of paclitaxel plasma levels > or = 0.05 micromol/l was observed, with a predicted time of 10.4 h to decrease cell count by 50%. A correlation was also observed between percentage reduction of platelet count and gemcitabine Cmax, with a predicted effective concentration to induce a 50% decrease of 14.3 microg/ml.

CONCLUSION

This study demonstrates the lack of interaction between drugs, the nonproportional pharmacokinetics of gemcitabine at higher doses and the Emax relationship of paclitaxel and gemcitabine with neutrophil and platelet counts, respectively. In addition, gemcitabine 1,500 mg/m2 is the recommended dosage in combination with paclitaxel 100 mg/m2 for future phase II studies, due to its predictable kinetic behaviour and less severe thrombocytopenia than expected.