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      A review of lapatinib ditosylate in the treatment of refractory or advanced breast cancer

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          Abstract

          Breast cancer remains a leading cause of disease and death among women throughout the world. Despite advances in drug therapy, development of novel and improved drugs for breast cancer continues to be of great interest. Lapatinib is a novel dual receptor tyrosine kinase inhibitor that is a selective and potent inhibitor of ErbB-1 and ErbB-2 tyrosine kinases, both of which are growth promoting factors overexpressed in some breast cancers. Cell-based assays have proven lapatinib to be a potent inhibitor of ErbB-1 and ErbB-2 activation and breast cancer cell proliferation. In pharmacokinetic studies, lapatinib has shown mostly linear elimination kinetics over the daily dose range of 10–1600 mg and is metabolized by CYP3A4/5 and CYP2C19. Phase I, II, and III clinical trials involving lapatinib as monotherapy or in combination have shown promise for the treatment of advanced and metastatic breast cancer. Drug-drug interactions may occur secondary to concomitant administration of either CYP450 inhibitors or inducers. While lapatinib appear to be a promising addition to breast cancer therapy, several questions remain to be answered before its optimal role is elucidated.

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          Most cited references 73

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          Safety and efficacy of an attenuated vaccine against severe rotavirus gastroenteritis.

          The safety and efficacy of an attenuated G1P[8] human rotavirus (HRV) vaccine were tested in a randomized, double-blind, phase 3 trial. We studied 63,225 healthy infants from 11 Latin American countries and Finland who received two oral doses of either the HRV vaccine (31,673 infants) or placebo (31,552 infants) at approximately two months and four months of age. Severe gastroenteritis episodes were identified by active surveillance. The severity of disease was graded with the use of the 20-point Vesikari scale. Vaccine efficacy was evaluated in a subgroup of 20,169 infants (10,159 vaccinees and 10,010 placebo recipients). The efficacy of the vaccine against severe rotavirus gastroenteritis and against rotavirus-associated hospitalization was 85 percent (P<0.001 for the comparison with placebo) and reached 100 percent against more severe rotavirus gastroenteritis. Hospitalization for diarrhea of any cause was reduced by 42 percent (95 percent confidence interval, 29 to 53 percent; P<0.001). During the 31-day window after each dose, six vaccine recipients and seven placebo recipients had definite intussusception (difference in risk, -0.32 per 10,000 infants; 95 percent confidence interval, -2.91 to 2.18; P=0.78). Two oral doses of the live attenuated G1P[8] HRV vaccine were highly efficacious in protecting infants against severe rotavirus gastroenteritis, significantly reduced the rate of severe gastroenteritis from any cause, and were not associated with an increased risk of intussusception. (ClinicalTrials.gov numbers, NCT00139347 and NCT00263666.) Copyright 2006 Massachusetts Medical Society.
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            Activity of the dual kinase inhibitor lapatinib (GW572016) against HER-2-overexpressing and trastuzumab-treated breast cancer cells.

            Lapatinib (GW572016) is a selective inhibitor of both epidermal growth factor receptor (EGFR) and HER-2 tyrosine kinases. Here, we explore the therapeutic potential of lapatinib by testing its effect on tumor cell growth in a panel of 31 characterized human breast cancer cell lines, including trastuzumab-conditioned HER-2-positive cell lines. We further characterize its activity in combination with trastuzumab and analyze whether EGFR and HER-2 expression or changes induced in the activation of EGFR, HER-2, Raf, AKT, or extracellular signal-regulated kinase (ERK) are markers of drug activity. We report that concentration-dependent antiproliferative effects of lapatinib were seen in all breast cancer cell lines tested but varied significantly between individual cell lines with up to 1,000-fold difference in the IC(50)s (range, 0.010-18.6 micromol/L). Response to lapatinib was significantly correlated with HER-2 expression and its ability to inhibit HER-2, Raf, AKT, and ERK phosphorylation. Long-term in vivo lapatinib studies were conducted with human breast cancer xenografts in athymic mice. Treatment over 77 days resulted in a sustained and significant reduction in xenograft volume compared with untreated controls. For the combination of lapatinib plus trastuzumab, synergistic drug interactions were observed in four different HER-2-overexpressing cell lines. Moreover, lapatinib retained significant in vitro activity against cell lines selected for long-term outgrowth (>9 months) in trastuzumab-containing (100 microg/mL) culture medium. These observations provide a clear biological rationale to test lapatinib as a single agent or in combination with trastuzumab in HER-2-overexpressing breast cancer and in patients with clinical resistance to trastuzumab.
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              Anti-tumor activity of GW572016: a dual tyrosine kinase inhibitor blocks EGF activation of EGFR/erbB2 and downstream Erk1/2 and AKT pathways.

              Dual EGFR/erbB2 inhibition is an attractive therapeutic strategy for epithelial tumors, as ligand-induced erbB2/EGFR heterodimerization triggers potent proliferative and survival signals. Here we show that a small molecule, GW572016, potently inhibits both EGFR and erbB2 tyrosine kinases leading to growth arrest and/or apoptosis in EGFR and erbB2-dependent tumor cell lines. GW572016 markedly reduced tyrosine phosphorylation of EGFR and erbB2, and inhibited activation of Erk1/2 and AKT, downstream effectors of proliferation and cell survival, respectively. Complete inhibition of activated AKT in erbB2 overexpressing cells correlated with a 23-fold increase in apoptosis compared with vehicle controls. EGF, often elevated in cancer patients, did not reverse the inhibitory effects of GW572016. These observations were reproduced in vivo, where GW572016 treatment inhibited activation of EGFR, erbB2, Erk1/2 and AKT in human tumor xenografts. Erk1/2 and AKT represent potential biomarkers to assess the clinical activity of GW572016. Inhibition of activated AKT in EGFR or erbB2-dependent tumors by GW572016 may lead to tumor regressions when used as a monotherapy, or may enhance the anti-tumor activity of chemotherapeutics, since constitutive activation of AKT has been linked to chemo-resistance.
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                Author and article information

                Journal
                Ther Clin Risk Manag
                Therapeutics and Clinical Risk Management
                Therapeutics and Clinical Risk Management
                Dove Medical Press
                1176-6336
                1178-203X
                August 2007
                August 2007
                : 3
                : 4
                : 665-673
                Affiliations
                [1 ]School of Pharmacy, Wingate University Wingate, North Carolina, USA
                [2 ]Northeast Medical Center Concord, North Carolina, USA
                Author notes
                Correspondence: Michael H Nelson Campus Box 3087, School of Pharmacy, Wingate University, Wingate, North Carolina 28174, USA Tel +1 704 233 8351 Email mnelson@ 123456wingate.edu
                Article
                2374939
                18472989
                © 2007 Dove Medical Press Limited. All rights reserved
                Categories
                Review

                Medicine

                breast cancer, tyrosine kinase inhibitor, gw572016, lapatinib

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