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Ciuffreda L.,Regina Elena Cancer Institute | Di Sanza C.,Regina Elena Cancer Institute | Cesta Incani U.,Regina Elena Cancer Institute | Eramo A.,Oncology and Molecular Medicine | And 17 more authors.
Journal of Molecular Medicine | Year: 2012

The mitogen-activated protein kinase (MAPK) and PI3K pathways are regulated by extensive crosstalk, occurring at different levels. In tumors, transactivation of the alternate pathway is a frequent "escape" mechanism, suggesting that combined inhibition of both pathways may achieve synergistic antitumor activity. Here we show that, in the M14 melanoma model, simultaneous inhibition of both MEK and mammalian target of rapamycin (mTOR) achieves synergistic effects at suboptimal concentrations, but becomes frankly antagonistic in the presence of relatively high concentrations of MEK inhibitors. This observation led to the identification of a novel crosstalk mechanism, by which either pharmacologic or genetic inhibition of constitutive MEK signaling restores phosphatase and tensin homolog (PTEN) expression, both in vitro and in vivo, and inhibits downstream signaling through AKT and mTOR, thus bypassing the need for double pathway blockade. This appears to be a general regulatory mechanism and is mediated by multiple mechanisms, such as MAPK-dependent c-Jun and miR-25 regulation. Finally, PTEN upregulation appears to be a major effector of MEK inhibitors' antitumor activity, as cancer cells in which PTEN is inactivated are consistently more resistant to the growth inhibitory and anti-angiogenic effects of MEK blockade. © 2012 Springer-Verlag. Source

Massimino M.,Pediatric Unit | Biassoni V.,Pediatric Unit | Miceli R.,Biometry and Bioinformatics Unit | Schiavello E.,Pediatric Unit | And 19 more authors.
Journal of Neuro-Oncology | Year: 2014

Radiotherapy is the only treatment definitely indicated for diffuse pontine gliomas (DIPG). Findings on the role of EGFR signaling in the onset of childhood DIPG prompted the use of nimotuzumab, an anti-EGFR monoclonal antibody. Assuming a potential synergy with both radiotherapy and vinorelbine, a pilot phase 2 protocol was launched that combined nimotuzumab with concomitant radiation and vinorelbine. An amendment in July 2011 introduced re-irradiation at relapse. The primary endpoint for first-line treatment was objective response rate (CR + PR + SD) according to the RECIST. This report concerns the outcome of this strategy as a whole. Vinorelbine 20 mg/m2 was administered weekly, with nimotuzumab 150 mg/m2 in the first 12 weeks of treatment; radiotherapy was delivered from weeks 3 to 9, for a total dose of 54 Gy. Vinorelbine 25 mg/m2 and nimotuzumab were given every other week thereafter until the tumor progressed or for up to 2 years. Re-irradiation consisted of 19.8 Gy, fractionated over 11 days. Baseline and latest MRIs were assessed blindly by an outside neuroradiologist. Twenty five children (mean age 7.4 years) were enrolled as of August 2009 (median follow-up 29 months). A response was observed in 24/25 patients (96 %). The nimotuzumab/vinorelbine combination was very well tolerated, with no acute side-effects. Eleven of 16 locally-relapsing patients were re-irradiated. One-year PFS and OS rates were 30 ± 10 % and 76 ± 9 %, respectively; 2-year OS was 27 ± 9 %; the median PFS and OS were 8.5 and 15 months, respectively. This strategy generated interesting results and warrants further investigation. © 2014 Springer Science+Business Media New York. Source

Germano G.,IRCCS Clinical and Research Institute Humanitas | Frapolli R.,Mario Negri Institute for Pharmacological Research | Belgiovine C.,IRCCS Clinical and Research Institute Humanitas | Anselmo A.,IRCCS Clinical and Research Institute Humanitas | And 21 more authors.
Cancer Cell | Year: 2013

There is widespread interest in macrophages as a therapeutic target in cancer. Here, we demonstrate that trabectedin, a recently approved chemotherapeutic agent, induces rapid apoptosis exclusively in mononuclear phagocytes. In four mouse tumor models, trabectedin caused selective depletion of monocytes/macrophages in blood, spleens, and tumors, with an associated reduction of angiogenesis. By using trabectedin-resistant tumor cells and myeloid cell transfer or depletion experiments, we demonstrate that cytotoxicity on mononuclear phagocytes is a key component of its antitumor activity. Monocyte depletion, including tumor-associated macrophages, was observed in treated tumor patients. Trabectedin activates caspase-8-dependent apoptosis; selectivity for monocytes versus neutrophils and lymphocytes is due to differential expression of signaling and decoy TRAIL receptors. This unexpected property may be exploited in different therapeutic strategies. © 2013 Elsevier Inc. Source

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