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The Promise of Pharmacogenomics: Gemcitabine and Pemetrexed

November 2nd 2004

Although no overall differences in survival have been observed betweenthe many chemotherapy combinations in non–small-cell lungcancer, the clinical application of mRNA expression levels of amplifiedgenes may disclose many genetic influences on cytotoxic drug sensitivityand enable clinicians to tailor chemotherapy according to eachindividual’s gene profile. Specifically, the assessment of ribonucleotidereductase subunit M1 and thymidylate synthase mRNA expression levelsmight select patients who benefit from gemcitabine (Gemzar) orpemetrexed (Alimta) combinations. Until recently, clinical prognosticfactors such as performance status, weight loss, and lactate dehydrogenasewere the only parameters used to predict chemotherapy responseand survival. However, accumulated data indicate that overexpressionof genes involved in cancer glycolysis pathways plays an important role,and might be an independent mechanism of chemoresistance. Thedysregulation of glycolytic genes is affected by growth signals involvingthe PI3K/Akt pathway and downstream genes such as hypoxiainduciblefactor-1-alpha. One can thus envision that substantial improvementsin therapeutic outcome could benefit from the integrationof tailored ribonucleotide reductase-dependent chemotherapy, ribonucleotidereductase antisense therapy, and targeted therapy.


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Induction Therapy for Early-Stage Non-Small-Cell Lung Cancer

July 1st 2004

Data from adjuvant trials clearly indicate that one of the most importantproblems in patients with resected non-small-cell lung cancer(NSCLC) is compliance to chemotherapy. In the postoperative setting,significant comorbidities and incomplete recovery after surgery oftenmake it difficult for patients to tolerate or comply with systemic therapy.Therefore, it may be preferable to deliver chemotherapy before surgeryas "neoadjuvant" or "induction" chemotherapy. The rationale for usinginduction chemotherapy is based on evidence that chemotherapymight reduce tumor burden and possess activity againstmicrometastases, resulting in improved results by surgery, radiotherapy,or a combination. Moreover, induction therapy facilitates in vivo assessmentof tumor response or resistance. Potential drawbacks includethe risk of perioperative complications, and the possibility that the tumormass may become unresectable due to disease progression. Duringthe past decade, four phase III randomized trials evaluated the roleof induction chemotherapy in stage IIIA NSCLC. The first three studiesconsistently showed that induction chemotherapy improves survivalcompared with surgery alone. More recently, a large phase III trialperformed by French investigators suggested a survival benefit in stageI/II patients, but not stage IIIA. The high activity of new platinumbasedchemotherapy-based on response rate and 1-year survival inadvanced disease-reinforces the rationale for the use of these newcombinations in early-stage NSCLC, especially for a subset of patientstraditionally treated with surgery alone. Several phase III trials arecurrently evaluating the role of new doublets as induction chemotherapy;these are discussed in the article. The results of these ongoingphase III trials should help clarify the role of induction chemotherapyin early-stage disease.


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Topoisomerase I Inhibitors in the Combined-Modality Therapy of Lung Cancer

June 1st 2004

Locally advanced non–small-cell lung cancer represents 30% to 40%of all pulmonary malignancies. Most patients will die of the diseaseafter aggressive contemporary treatments. Therefore, significant improvementin therapeutic methods must be implemented to improveoverall survival rates. The arrival of a new generation of chemotherapeuticagents-including the taxanes, gemcitabine (Gemzar), andtopoisomerase inhibitors such as irinotecan (Camptosar) and topotecan(Hycamtin)-offers the hope of significant advances in the treatmentof lung cancer. Irinotecan and topotecan are camptothecin derivativesthat inhibit topoisomerase I enzyme. It is believed that topoisomerase Iinhibitors stabilize a DNA/topoisomerase I complex and interact withreplication machinery to cause cell death. A significant amount of datademonstrates that these topoisomerase I inhibitors also act asradiosensitizers. With the increasing data that support concurrentchemoradiation treatment for malignancies, including lung cancer andhead and neck cancers, there is an impetus to pursue the additionaldrugs that may potentially improve local control and survival. Irinotecanis undergoing early clinical trials in the combined-modality setting inseveral different disease sites. This paper will review the data on therole of camptothecin derivatives as a radiosensitizer and as a componentof combined-modality therapy for lung cancer. It is hoped thatnewer treatment strategies, like the combination of radiation andtopoisomerase I inhibitors, will have a significant impact on cure ratesin the future.


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State-of-the-Art Treatment for Advanced NonSMQ-8211-SMQSmall-Cell Lung Cancer

December 1st 2003

Patients with locally advanced or metastatic nonSMQ-8211-SMQsmall-cell lungcancer (stage III and IV) who are not candidates for surgery and exhibitgood performance status are typically treated with concurrent radiationand platinum-based chemotherapy for disease palliation. Platinum-based chemotherapies, used alone or with radiation therapy, offera small but significant survival benefit compared with supportivecare. The incorporation of first-line agents such as gemcitabine(Gemzar), vinorelbine (Navelbine), and paclitaxel, as well as secondlineagents such as docetaxel (Taxotere), in doublet and triplet combinationshas had a further significant therapeutic impact. Randomizedtrials have shown that cisplatin-based therapy in combination with newagents results in improved 1- and 2-year survival rates in patients withadequate performance status. The 1-year survival benefit has significantlyimproved, with greater symptom relief and improved quality oflife in these patients. Thus, delaying disease progression with combinationchemotherapy appears both beneficial and cost-effective in patientswith advanced nonSMQ-8211-SMQsmall-cell lung cancer. Newer approachesSMQ-8212-SMQincluding targeting critical signaling pathways, such as tyrosine kinasereceptors, angiogenesis, and downstream signal transductionmechanismsSMQ-8212-SMQmay provide novel agents with an improved toxicity profileand the potential for better disease management.


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Erlotinib: Preclinical Investigations

November 2nd 2003

Erlotinib (Tarceva) is an orally available selective small-moleculeinhibitor of HER1/EGFR tyrosine kinase with a 50% inhibitory concentrationof 2 nM for purified tyrosine kinase. This agent has beenshown to produce stasis or regression of tumor growth in human cancerxenograft models, including non-small-cell lung cancer models.Ongoing preclinical investigations indicate that inhibition of the MAPKand Atk signaling pathways downstream of HER1/EGFR may be requiredfor optimal antitumor effects. Erlotinib exhibits inhibition ofMAPK and Atk kinases at concentrations higher than those requiredfor HER1/EGFR tyrosine kinase inhibition; such findings suggest thatmaximal inhibition of HER1/EGFR, requiring high erlotinib doses, isnecessary for optimum antitumor activity. These considerations aresupported by tumor models, including non-small-cell lung cancermodels, showing dose-related antitumor effects up to high doses oferlotinib. Erlotinib exhibits additive antitumor effects when combinedwith chemotherapeutic agents (cisplatin, doxorubicin, paclitaxel,gemcitabine [Gemzar], and capecitabine [Xeloda]), radiation therapy,and other targeted agents (eg, bevacizumab [Avastin]). Recent studiesindicate that erlotinib inhibits the EGFRvIII mutant at concentrationshigher than those required for inhibition of wild-type receptor. Ongoinginvestigation will help to determine optimal dosing and dose frequencyof erlotinib in various cancers in the clinical setting.


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Risk Models for Neutropenia in Patients With Breast Cancer

November 1st 2003

Breast cancer is the most common noncutaneous malignancy inwomen in industrialized countries. Chemotherapy prolongs survival inpatients with early-stage breast cancer, and maintaining the chemotherapydose intensity is crucial for increasing overall survival. Manypatients are, however, treated with less than the standard dose intensitybecause of neutropenia and its complications. Prophylactic colonystimulatingfactor (CSF) reduces the incidence and duration of neutropenia,facilitating the delivery of the planned chemotherapy doses.Targeting CSF to only at-risk patients is cost-effective, and predictivemodels are being investigated and developed to make it possible forclinicians to identify patients who are at highest risk for neutropeniccomplications. Both conditional risk factors (eg, the depth of the firstcycleabsolute neutrophil count nadir) and unconditional risk factors(eg, patient age, treatment regimen, and pretreatment blood cell counts)are predictors of neutropenic complications in early-stage breast cancer.Colony-stimulating factor targeted toward high-risk patients startingin the first cycle of chemotherapy may make it possible for fulldoses of chemotherapy to be administered, thereby maximizing patientbenefit. Recent studies of dose-dense chemotherapy regimens with CSFsupport in early-stage breast cancer have shown improvements in disease-free and overall survival, with less hematologic toxicity than withconventional therapy. These findings could lead to changes in how earlystagebreast cancer is managed.

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