process is initiated by the binding of albumin to an endothelium surface, 60-kDa glycoprotein (gp60) receptor (albondin), which will then bind with an intracellular protein (caveolin-1) to cell assay result in the invagination of the endothelium membrane to form transcytotic vesicles, the caveolae (9). The caveolae will subsequently move across the cytoplasm Inhibitors,research,lifescience,medical and release the albumin and its conjugated compound into the extracellular space (the peritumoral microenvironment) where the albumin will bind to SPARC (secreted protein acid and rich in cysteine), an extracellular matrix albumin-binding glycoprotein that is structurally and functionally closely related to gp60, and overexpressed in a variety of cancers, including breast cancer, gastric cancer and pancreatic cancer. Inhibitors,research,lifescience,medical Nab-Dorsomorphin solubility paclitaxel (Abraxane®) is a cremophor (CrEL)-free, albumin-bound, nanoparticle formulation of paclitaxel. Its CrEL-free formulation permits nab-paclitaxel to be administered within a shorter infusion period of time (30 minutes) and without the requirement
of routine pre-medications for preventing the hypersensitivity reactions in association with the administration of cremophor solvent-based paclitaxel (10). In preclinical study, the transport of radiolabeled paclitaxel across the endothelial cell monolayer in Inhibitors,research,lifescience,medical vitro, and intratumor paclitaxel accumulation after equal doses of paclitaxel in vivo were both significantly enhanced by 4.2-folds (P < 0.0001) and 33% (P < 0.0001), respectively, for nab-paclitaxel as compared with CrEL-paclitaxel with an increase 4.2 folds. In addition, Inhibitors,research,lifescience,medical endothelial transcytosis was completely inhibited by inhibitor of gp60/caveolar transport, methyl ß-cyclodextrin (11). These observations supported that gp60-mediated
transcytosis and SPARC-aided sequestration may be an important biological Inhibitors,research,lifescience,medical pathway to target tumor cells by novel albumin-bound therapeutics. In a phase I trial, the maximum tolerated dose (MTD) of intravenous injection nab-paclitaxel monotherapy, every 3 weeks in 19 patients with standard therapy-failure solid tumors was 300 mg/m2. No acute hypersensitivity reactions were observed. The most frequent toxicities were myelo-suppression, sensory neuropathy, nausea/vomiting, arthralgia and alopecia (12). The drug has subsequently approved for the Entinostat treatment of metastatic breast cancer after failure of combination chemotherapy or relapse within 6 months of adjuvant chemotherapy. The commonly used dose/schedule was 260 mg/m2, 30-min intravenous injection, every 3 weeks. Because SPARC is frequently overexpressed and associated with poor clinical outcomes in pancreatic cancer, Von Hoff et al conducted a phase I/II study to evaluate the MTD of weekly nab-paclitaxel (100 – 150 mg/m2/week) in combination with gemcitabine (1000 mg/m2/week), and the therapeutic efficacies of the regimen. Both agents were given on day 1, 8, and 15 every 28 days ((13)).