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PubMed2005

The relationship between folate transport activity at low pH and reduced folate carrier function in human Huh7 hepatoma cells.

Transport of folates and antifolates in both hepatocytes and Huh7 human hepatoma cells is characterized by a low-pH optimum. Studies were undertaken to determine the extent to which this transport activity is mediated by the reduced folate carrier (RFC) in Huh7 human hepatoma cells. RFC expression was ablated by chemical mutagenesis and antifolate selective pressure with PT632 resulting in the PT632(R) subline in which RFC mRNA could not be detected. Methotrexate (MTX) influx in these cells at pH 7.4 was reduced by 70%, leaving substantial residual RFC-independent influx while influx of MTX and folic acid at pH 5.5 was not significantly decreased. The influx K(t) for folic acid and MTX at pH 5.5 in PT632(R) cells was 0.36 and 1.5 microM, respectively. The affinity of the low pH transporter in PT632(R) cells was highest for pemetrexed (K(i)=140 nM), very low for PT632 (K(i)=77 microM), and was stereospecific for the natural isomer (6S) of 5-formyltetrahydrofolate. In Huh7 cells transiently transfected with an RFC siRNA, RFC expression was reduced by 60% resulting in a 40% decrease in MTX influx at pH 7.4 but only a very small (5%) reduction in MTX or folic acid influx at pH 5.5. These data indicate that MTX transport in Huh7 cells at neutral pH is mediated largely by RFC while at pH 5.5 the predominant route of transport is independent of RFC.

Biological Transport↗
PubMed2006

Methylthioadenosine phosphorylase gene deletions are frequently detected by fluorescence in situ hybridization in conventional chondrosarcomas.

Chondrosarcomas are the second most common primary malignant tumor of bone. Chemotherapy for conventional chondrosarcomas is generally ineffective. Methylthioadenosine phosphorylase (MTAP) is a ubiquitous enzyme, essential in the salvage pathway of adenine and in methionine synthesis. MTAP-deficient cells are more susceptible than wild-type cells to pharmacologic inhibitors of de novo purine synthesis. Homozygous deletions of MTAP have been reported in hematologic and solid tumor malignancies. Based on these observations, we investigated the frequency of MTAP deletions in conventional, grade II chondrosarcomas by fluorescence in situ hybridization (FISH) analysis: 23 conventional, grade II chondrosarcoma patient samples from the Cleveland Clinic Foundation were analyzed for MTAP deletions. Nuclei were successfully extracted from 14 of 23 samples (61% evaluable) for FISH analysis: 7 of 14 samples (50%) showed either homozygous or hemizygous deletion of the MTAP gene, 6 of 14 (43%) failed to show deletion, and 1 of 14 (7%) was inconclusive. These findings suggest that approximately one-half of conventional, grade II chondrosarcomas may be preferentially sensitive to pharmacologic inhibitors of de novo purine synthesis. The present study led to development by the Intergroup Coalition Against Sarcomas of a phase II trial of pemetrexed, a multitargeted anti-folate, for advanced chondrosarcomas.

Chondrosarcoma↗
PubMed2005

[Recent progress in treatment of malignant pleural mesothelioma].

Incidence of malignant pleural mesothelioma will rise until 2030-2040 because the elapsed time between exposure and diagnostic is up to several decades. Prognosis remains very poor with median survival less than one year and five-year survival not exceeding 5%. As compared to 1999, standart treatment adds chemotherapy with cisplatin and pemetrexed to local radiotherapy for prevention of local seeding after invasive diagnostic procedures. Despite various growth factors and their receptors are involved in malignant mesothelioma, first clinical trials of targeted therapies reported poor results. Multimodality therapy with extrapleural pneumonectomy and radiation therapy (+/-chemotherapy) can be of benefit in subgroups of patients but it cannot be recommended in a routine approach. As compared to bronchial carcinoma, inclusion of patients in clinical trials (using intensity-modulated radiation therapy) is the only way to somewhat improve results.

Chemotherapy, Adjuvant↗
PubMed2026

Clinical pharmacokinetics of afatinib: A systematic review.

BACKGROUND: Afatinib is commonly used in the treatment of non-small cell lung cancer (NSCLC). This systematic review summarizes clinical pharmacokinetics (PK) evidence focusing on the effect of disease state and drug interactions on afatinib exposure. METHODS: Google Scholar, Science Direct, PubMed, and the Cochrane library were searched for human studies reporting the clinical PK of afatinib. The search yielded 24 articles that met the predefined inclusion criteria. RESULTS: Afatinib exposure increased slightly more than dose proportionally, with higher doses producing greater AUC0-24 and Cmax values. The apparent oral clearance reported after administration of the oral solution was lower than that observed following tablet administration. The Cmax of afatinib increases by 38.5% after coadministration with ritonavir and exposure decreases 34.3% with rifampicin. The Cmax decreases 31.45% when given with pemetrexed. Both the AUC0-24 and Cmax increase in NSCLC and tumor state. The AUC0-24 of afatinib is 2.61 folds higher following multiple oral doses among patients with solid tumors. Afatinib exposure is 22.1 % higher in renal impaired patients than in healthy controls. In grade 2 diarrhea, the AUC0-24 of afatinib is 83.93% higher as than in grade 0-1 diarrhea in solid tumor patients. CONCLUSION: This systematic review provides an updated synthesis of clinical PK evidence on afatinib. Afatinib exposure is influenced by dose, repeated administration, renal impairment, diarrhea associated toxicity, and P-glycoprotein mediated drug interactions. These findings may support individualized dosing, toxicity-guided dose adjustment, and future development of PK models for afatinib.

Humans↗
PubMed2004

Experimental therapy of malignant mesothelioma: new perspectives from anti-angiogenic treatments.

We reviewed the published literature of clinical studies in malignant mesothelioma (MM), including phase II as well as older single-agent and combination chemotherapy trials with more than 15 patients. While response rates exceeding 30% have been achieved with established cytotoxic drugs in MM therapy, novel chemotherapeutic agents and their combinations appear more promising. This applies especially to the anti-metabolites (i.e. pemetrexed) that produced response rates of up to 45% in combination with platinum compounds. Moreover, agents targeting novel proliferative and survival pathways in MM are developed to improve treatment outcomes. Here, we focused on the role of several angiogenic growth factors in MM biology and the data of MM-oriented studies on angiostatic agents tested in a phase I-II trial. It seems likely that no single treatment modality will be effective by itself. Studies that use combinations of the newer agents, including angiostatic drugs, with chemotherapy, should be conducted.

Angiogenesis Inhibitors↗
PubMed2006

The role of multidrug resistance efflux transporters in antifolate resistance and folate homeostasis.

Members of the ATP-binding cassette (ABC) transporters including P-glycoprotein (Pgp/ABCB1), multidrug resistance proteins (MRPs/ABCC) as well as breast cancer resistance protein (BCRP/ABCG2) function as ATP-dependent drug efflux transporters, which form a unique defense network against multiple chemotherapeutic drugs and cellular toxins. Among antitumor agents is the important group of folic acid antimetabolites known as antifolates. Antifolates such as methotrexate (MTX), pemetrexed and raltitrexed exert their cytotoxic activity via potent inhibition of folate-dependent enzymes essential for purine and pyrimidine nucleotide biosynthesis and thereby block DNA replication. Overexpression of MRPs and BCRP confers resistance upon malignant cells to various hydrophilic and lipophilic antifolates. Apart from their central role in mediating resistance to antifolates and other anticancer drugs, MRPs and BCRP have been recently shown to transport naturally occurring reduced folates. This was inferred from various complementary systems as follows: (a) Cell-free systems including ATP-dependent uptake of radiolabeled folate/MTX into purified inside-out membrane vesicles from stable transfectants and/or cells overexpressing these transporters, (b) Decreased accumulation of radiolabeled folate/MTX in cultured tumor cells overexpressing these transporters, as well as (c) In vivo rodent models such as Eisi hyperbillirubinemic rats (EHBR) that hereditarily lack MRP2 in their canalicular membrane and thereby display a bile that is highly deficient in various reduced folate cofactors and MTX, when compared with wild type Sprague-Dawley (SD) rats. In all cases, these folate/antifolate transporters functioned as high capacity, low affinity ATP-driven exporters. While the mechanism of cellular retention of (anti)folates is mediated via (anti)folylpolyglutamylation, certain efflux transporters including MRP5 (ABCC5) and BCRP were shown to transport both mono-, di- as well as triglutamate derivatives of MTX and folic acid. Furthermore, overexpression of MRPs and BCRP has been shown to result in decreased cellular folate pools, whereas loss of ABC transporter expression brought about a significant expansion in the intracellular reduced folate pool. The latter finding has important implications to antifolate-based chemotherapy as an augmented cellular folate pool results in a significant level of resistance to certain antifolates. Hence, the aims of the present review are: (a) To summarize and discuss the cumulative evidence supporting a functional role for various multidrug resistance efflux transporters of the ABC superfamily which mediate resistance to hydrophilic and lipophilic antifolates, (b) To describe and evaluate the recent data suggesting a role for these efflux transporters in regulation of cellular folate homeostasis under folate replete and deplete conditions. Furthermore, novel developments and future perspectives regarding the identification of novel antifolate target proteins and mechanisms of action, as well as rationally designed emerging drug combinations containing antifolates along with receptor tyrosine kinase inhibitors are being discussed.

ATP Binding Cassette Transporter, Subfamily G, Mem↗
PubMed2006

Biology and management of malignant pleural mesothelioma.

Malignant mesothelioma is an aggressive tumour, with a poor prognosis and an increasing incidence as a result of widespread exposure to asbestos. The results of the treatments available are poor. Surgery and radiotherapy have a limited role in highly selected patients and systemic therapy is the only potential treatment option for the majority of patients. Despite some definite activity of the novel antifolates such as pemetrexed and raltitrexed, the results, even in combination with platinating agents, are still modest, with a median survival of approximately one year. The better understanding of the biology of mesothelioma makes the assessment of a number of targeted agents particularly interesting. Unfortunately, the targeted agents imatinib, gefitinib, erlotinib and thalidomide have been shown to be ineffective in unselected patients. Studies with anti-angiogenesis agents are ongoing. An improvement of the knowledge of major molecular pathways involved in malignant mesothelioma is needed in order to define proper targets for the systemic treatment of this disease.

Antineoplastic Agents↗
PubMed2004

Chemotherapy in stage-IV NSCLC.

Since cisplatin-based chemotherapy was proven to increase survival in advanced and metastatic NSCLC various new combinations have been tested. The third generation regimens which showed almost comparable efficacy among each other in randomised trials often proved a better response rate and time to progression combined with a remarkable reduction of toxic side effects compared to "classic" combinations, whereas most studies only noted a modest increase in survival. Two-drug regimens were more effective than monotherapy but at the expense of significantly increased toxicity, while monotherapy compared to BSC improved quality of life and survival. The novel antifolate Pemetrexed proved comparable activity to docetaxel with significantly reduced toxicities.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2005

Photodynamic therapy as an adjunct to surgery for malignant pleural mesothelioma.

Malignant pleural mesothelioma (MPM) is increasingly observed in industrial countries. Despite concerted efforts and combined treatments including surgery, chemotherapy and irradiation patients eventually succumb from relentless local progression of the disease. Recent publications have demonstrated an improved response rate with the cytostatic agent pemetrexed which will be tested in a neoadjuvant setting followed by surgery. However, effective tumor control requires new loco-regional treatment modalities, eventually in combination with neoadjuvant chemotherapy. Intraoperative photodynamic therapy (PDT) of the chest cavity has been proposed as an attractive treatment concept for MPM since a selective treatment of the tumor bed following resection has the potential to improve local tumor control. It has been shown to afford tumor destruction in patients with mesothelioma but efficiency and selectivity is not yet sufficient for routine clinical application. Experimental work on MPM has shown that tumor selectivity of PDT depend on treatment conditions and can be improved by structural modification and improved targeting of the sensitizers. Refinements of PDT for mesothelioma will depend on a more detailed understanding of the pathways for preferential sensitizer accumulation within the tumor as well as on synergistic effects between PDT and chemotherapeutic agents.

Animals↗
PubMed2005

Second-line treatment for advanced non-small cell lung cancer: a systematic review.

BACKGROUND: Among advanced non-small cell lung cancer (NSCLC) patients, most will resist or relapse after first-line chemotherapy. As a result, second-line therapy has been a major focus for clinical research. MATERIALS AND METHODS: A systematic review was carried out from 1996 to February 2005. RESULTS: Second-line chemotherapy provides pre-treated NSCLC patients with a clear survival advantage. Docetaxel 75 mg/m(2) every 3 weeks is the present standard second-line chemotherapy. Despite promising results regarding efficacy and toxicity in phase III studies, a docetaxel weekly schedule could not be recommended. Pemetrexed recently emerged as an alternative with similar efficacy and less toxicity. Although the combination of two drugs was not associated with a survival benefit when compared with single-agent chemotherapy, such regimens induced a dramatic increase in toxicities and therefore mono-chemotherapy remains the standard as second-line therapy. Finally, few new agents were reported with better results than those used previously and clinical research on second-line therapy currently focuses on combinations with targeted therapies. CONCLUSION: Second-line chemotherapy offers NSCLC patients a small but significant survival improvement. However, this field of clinical research needs further investigations in order to answer certain remaining questions especially concerning targeted therapies.

Antineoplastic Agents↗
PubMed2003

In vitro effects of combinations of cis-amminedichloro (2-methylpyridine) platinum (II) (ZD0473) with other novel anticancer drugs on the growth of SBC-3, a human small cell lung cancer cell line.

Among numerous clinical regimens of combination chemotherapy, synergy has been observed to be particularly marked with combinations containing cisplatin (CDDP). However, the clinical use of CDDP has sometimes been limited by acquired resistance. The new-generation platinum drug, ZD0473, was synthesized with the aim of hindering the reaction of the drug with thiols, by the introduction of a 2-methylpyridine ligand. This enables the drug to exert antitumor activity against cisplatin-resistant cancer cells with elevated glutathione and/or metallothionein levels. The drug was also shown experimentally to overcome cisplatin resistance due to impaired drug accumulation, and enhanced DNA repair/tolerance to platinum-DNA adducts. We investigated the effects of combinations of ZD0473 with other anticancer drugs on the growth of a human small-cell lung cancer cell line (SBC-3). Six novel anticancer drugs were tested: docetaxel (TXT), paclitaxel (TXL), vinorelbine (VNB), irinotecan (CPT-11), gemcitabine (GEM) and pemetrexed (MTA). The growth inhibitory effect of the drugs was measured by MTT assay and the effects of the combination regimens were evaluated by the combination index analysis method developed by Chou and Talalay. Synergy was demonstrated for the combination regimens of ZD0473-GEM and ZD0473-TXL, while an additive effect was observed with combinations containing TXT, VNB, CPT-11 or MTA. In the case of the ZD0473-GEM combination, synergy was observed over a wide range of inhibition levels at dose ratios of 50:1, 100:1 and 250:1. The level of synergy was equivalent to that observed for combinations of CDDP-etoposide, CDDP-GEM and nedaplatin-CPT-11. The results suggest that the combination of ZD0473 with GEM merits further investigation in small cell lung cancer.

Antimetabolites, Antineoplastic↗
PubMed2004

Inadequacy of the RECIST criteria for response evaluation in patients with malignant pleural mesothelioma.

UNLABELLED: The newly introduced Response Evaluation Criteria in Solid Tumors (RECIST), which relies on a single largest dimension of tumor rather than on the product of perpendicular diameters World Health Organisation (WHO) is intended to simplify the assessment of tumor response. PURPOSE: Is to evaluate the performance and validity of the RECIST compared to the WHO criteria. DESIGN: Thirty-four consecutive patients with bidimensionally measurable malignant pleural mesothelioma (MPM) were evaluated prospectively. RESULTS: In 27% (9/34) a discrepancy was found between the WHO and RECIST response evaluation 9% (3/34) concerned best responses and 18% (6/34) objective confirmed responses. In 24% (8/34) disease progression was missed by RECIST. The percentage of patients in whom one or more discordance's between WHO and RECIST were detected was 47, 88% due to underscoring by RECIST. In a subgroup of 24 MPM patients with bidimensionally measurable pleural lesions only, the discrepancy rate was 29%, always due to underscoring by RECIST. However, when in the same subgroup the modified RECIST response evaluation was used the discrepancy rate was 21% and in all cases due to underscoring by WHO. CONCLUSION: For MPM bidimensional WHO response evaluation cannot automatically be replaced by RECIST because MPM has a non-spherical growth pattern. Our recommendation is to use the WHO criteria for bidimensional measurable lesions, RECIST for unidimensional measurable lesions and a modified RECIST response evaluation, in which the short axis perpendicular to the chest wall is used, for thickened pleural rind disease, according to the method used in the recently completed pemetrexed (Alimta) trial for MPM.

Disease Progression↗
PubMed2005

Perspective on the development of new agents in thoracic cancers.

The development of several targeted agents that play a critical role in the growth and survival of carcinomas has paved the way for a new era in the treatment of patients with thoracic malignancies. The novel antimetabolite pemetrexed has emerged as a key agent in the treatment of advanced malignant pleural mesothelioma (MPM). Inhibitors of the epidermal growth factor receptor (EGFR) are one of many promising targeted therapies for non-small-cell lung cancer (NSCLC). By utilizing agents that specifically target the biochemical and molecular changes underlying cancer, it is possible to envision a future in which combinations of therapies treat cancer on multiple fronts, significantly enhancing tumor responses and improving survival beyond current expectations.

Antibodies, Monoclonal↗
PubMed2000

Downstream molecular determinants of response to 5-fluorouracil and antifolate thymidylate synthase inhibitors.

Thymidylate synthase (TS) is an essential enzyme for the de novo synthesis of thymidylate and subsequently DNA synthesis. TS has been used as a target for cancer chemotherapy in the development of fluoropyrimidines such as 5-fluorouracil (5-FU) and 5-fluorodeoxyuridine and of novel folate-based TS inhibitors such as ZD1694 (Tomudex, Raltitrexed), ZD9331, LY231514 (ALIMTA, Pemetrexed), AG337 (Thymitaq, Nolatrexed) and AG331. Although TS has been considered as a target for chemotherapy, the precise mechanism by which TS inhibition leads to cell death is still not completely resolved. TS inhibition results in depletion of dTTP, an essential precursor for DNA, and an increase in dUTP. This results in the so-called thymine-less death due to misincorporation of dUTP into DNA; its excision, catalysed by uracil-DNA glycosylase, results in DNA damage. Both this imbalance in dTTP/dUTP and DNA damage can result in induction of downstream events, leading to apoptosis. On the other hand a specific interaction exists between oncogenes and TS, by binding of TS protein to the p53 and c-myc RNA, while wt p53 can also inhibit TS promotor activity. TS inhibition by either 5-FU or antifolates can also result in a depression of TS protein mediated inhibition of TS mRNA translation leading to induction of more TS protein synthesis, and p53 protein may further deregulate this process. These complex indirect and direct interactions between oncogenes and TS may have as yet unclear clinical implications, since most data are based on in vitro or in vivo studies and some results are contradictive. In some preliminary clinical studies evidence was postulated for a combined prognostic role for TS and p53. This knowledge should be used to design clinical studies with the aim to deliver effective treatment to potentially sensitive patients both in the adjuvant setting and in advanced stage disease.

Antimetabolites, Antineoplastic↗
PubMed2004

Treatment approaches in patients with advanced non-small cell lung cancer and poor performance status.

It is estimated that 30% to 40% of patients with advanced non-small cell lung cancer (NSCLC) have a poor performance status (PS)-defined as a score of 2 or higher on the Eastern Cooperative Oncology Group scale-because of their disease burden, comorbidities, or both. Survival is shorter in these patients than in those with a better PS, and they do not tolerate chemotherapy as well. There is now evidence that PS2 patients with advanced NSCLC can benefit from single-agent chemotherapy with drugs such as vinorelbine, gemcitabine, paclitaxel, pemetrexed, and docetaxel and that combination chemotherapy may have additional advantages. The optimal treatment for PS2 patients with NSCLC, however, has yet to be determined. The case histories in this article demonstrate that PS2 patients are a heterogeneous group and that selecting the chemotherapy for each patient must take into consideration comorbidities and disease-related symptoms, as well as the potential toxicity of treatment. Large prospective clinical trials are needed to determine whether, and in which patients, combination chemotherapy or novel agents, such as the epidermal growth factor receptor inhibitors or paclitaxel poliglumex, have advantages. Three large phase III trials-Selective Targeting for Efficacy in Lung Cancer, Lower Adverse Reactions trials (STELLAR)-are now being conducted in PS2 patients with NSCLC. It is hoped that their findings will aid in determining the best treatment options for these patients.

Adult↗
PubMed2005

Combined modality trials in unresectable stage III non-small cell lung cancer: the Cancer and Leukemia Group B experience.

Lung cancer remains the leading cause of cancer-related mortality in the United States and 30% to 40% of newly diagnosed patients with non-small cell lung cancer present with regionally advanced and unresectable stage III disease. Combined-modality therapy is the current standard of care in patients with good performance status at the time of diagnosis and recent trials have suggested a survival advantage for the concurrent use of chemotherapy and thoracic radiation therapy at the risk of increased toxicity (mainly esophagitis and myelosuppression). The Cancer and Leukemia Group B has been instrumental in shaping the standard of care in the combined-modality approach to unresectable stage III non-small cell lung cancer. Currently, Cancer and Leukemia Group B is conducting trials evaluating novel thoracic radiation therapy strategies as well as the incorporation of molecularly targeted agents, yielding encouraging preliminary data. In addition, a change in the therapeutic platform is planned that explores a full-dose systemic approach with the antifolate pemetrexed that possesses radiosensitizing properties.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2005

Docetaxel in the management of advanced pancreatic cancer.

The poor outcome of pancreatic cancer with conventional treatment options emphasizes the need for continued research. The benefits of gemcitabine in improving quality of life and survival have been established in patients with advanced pancreatic cancer. Randomized clinical trials studying the addition of a second drug to gemcitabine, either a classic cytotoxic (5-fluorouracil, cisplatin, irinotecan, pemetrexed, oxaliplatin, or exatecan) or targeted agents (ie, the farnesyl transferase inhibitor R115777 or the metalloproteinase inhibitor marimastat) have not resulted in improvement in survival compared with gemcitabine alone. Although limited activity of docetaxel in patients with pancreatic adenocarcinoma has been reported in single-agent studies, attractive efficacy results have been documented with docetaxel in combination with other chemotherapeutic agents for the management of advanced pancreatic cancer. Phase I and II trials of docetaxel in combination with gemcitabine, irinotecan, 5-fluorouracil, or thalidomide, as well as trials of docetaxel and radiotherapy, suggest that docetaxel combinations in pancreatic cancer should be further studied in randomized trials.

Antineoplastic Agents, Phytogenic↗
PubMed2005

Chemotherapeutic gemcitabine doublets in pancreatic carcinoma.

Single-agent gemcitabine remains the standard treatment for advanced pancreas cancer. Results of four phase III trials reported in 2004 indicated no survival benefit for single-agent exatecan or combinations of exatecan, pemetrexed, and oxaliplatin with gemcitabine compared with gemcitabine alone. It is unclear whether a trend toward improved outcome with the gemcitabine/oxaliplatin combination was attributable to use of a fixed-dose rate infusion regimen of gemcitabine in the combination arm, a method of administration that appears to be associated with benefits compared with standard gemcitabine infusion. Novel approaches to treatment currently under investigation include refining schedules of administration of combination therapy, combining gemcitabine with molecular targeted therapy, and combining gemcitabine with low-molecular-weight heparin.

Antimetabolites, Antineoplastic↗