Breast cancer and the new taxanes: Focus on nab-paclitaxel
Emigrants and Immigrants
Nanoparticle albumin-bound (nab)-paclitaxel is the first approved enhanced-delivery taxane. By exploiting the properties of albumin (a natural carrier of hydrophobic molecules), including facilitated transport across the endothelial barrier (transcytosis) and binding to SPARC (secreted protein, acidic and rich in cysteine), nab-paclitaxel achieves greater intratumor concentrations and lower healthy tissue and blood concentrations compared with conventional solvent-based paclitaxel. In clinical trials comparing nab-paclitaxel with conventional solvent-based taxanes in metastatic breast cancer, nab-paclitaxel in every-3-week and weekly regimens has shown increased antitumor activity and a reduced risk of neutropenia. The risk of hypersensitivity reactions with nab-paclitaxel has been virtually nonexistent, despite the absence of pretreatment with antihistamines and steroids required for conventional paclitaxel. Phase II studies of nab-paclitaxel in combination with gemcitabine, capecitabine, and bevacizumab have shown favorable antitumor activity and no unexpected toxicities. The taxanes are valuable components of treatment for breast cancer. The development of nab-paclitaxel represents a success in overcoming the limitations of these valuable drugs. Data on additional uses of nab-paclitaxel in breast cancer and on second-generation enhanced-delivery taxanes are awaited. © 2008 Elsevier Inc. All rights reserved.
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