"OA02" peptide facilitates the precise targeting of paclitaxel-loaded micellar nanoparticles to ovarian cancer in vivo.

Micellar nanoparticles based on linear polyethylene glycol (PEG) block dendritic cholic acids (CA) copolymers (telodendrimers), for the targeted delivery of chemotherapeutic drugs in the treatment of cancers, are reported. The micellar nanoparticles have been decorated with a high-affinity "OA02" peptide against α-3 integrin receptor to improve the tumor-targeting specificity which is overexpressed on the surface of ovarian cancer cells. "Click chemistry" was used to conjugate alkyne-containing OA02 peptide to the azide group at the distal terminus of the PEG chain in a representative PEG(5k)-CA(8) telodendrimer (micelle-forming unit). The conjugation of OA02 peptide had negligible influence on the physicochemical properties of PEG(5k)-CA(8) nanoparticles and as hypothesized, OA02 peptide dramatically enhanced the uptake efficiency of PEG(5k)-CA(8) nanoparticles (NP) in SKOV-3 and ES-2 ovarian cancer cells via receptor-mediated endocytosis, but not in α-3 integrin-negative K562 leukemia cells. When loaded with paclitaxel, OA02-NPs had significantly higher in vitro cytotoxicity against both SKOV-3 and ES-2 ovarian cancer cells as compared with nontargeted nanoparticles. Furthermore, the in vivo biodistribution study showed OA02 peptide greatly facilitated tumor localization and the intracellular uptake of PEG(5k)-CA(8) nanoparticles into ovarian cancer cells as validated in SKOV3-luc tumor-bearing mice. Finally, paclitaxel (PTX)-loaded OA02-NPs exhibited superior antitumor efficacy and lower systemic toxicity profile in nude mice bearing SKOV-3 tumor xenografts, when compared with equivalent doses of nontargeted PTX-NPs as well as clinical paclitaxel formulation (Taxol). Therefore, OA02-targeted telodendrimers loaded with paclitaxel have great potential as a new therapeutic approach for patients with ovarian cancer.

Venous thromboembolism in uterine cancer.

OBJECTIVES: To determine the incidence, time course, and risk factors associated with the development of venous thromboembolism (VTE) and the effect of VTE on survival in women with uterine cancer. METHODS: Using the California Cancer Registry, the date, stage, and histology of all incident uterine cancer cases during 1993-1999 were identified. These cases were linked with the state's hospital discharge database, allowing identification of incident VTE events, after excluding cases with a previous history of VTE. Proportional hazards modeling was used to analyze the association of baseline risk factors with the development of VTE (<1 year), using major surgery as a time-dependent covariate. In a similar model for death (<2 years), VTE was included as a time-dependent covariate. RESULTS: Among 18,440 cases with uterine cancer, the 2-year cumulative incidence of VTE was 2.7%. The cumulative incidence varied from 1.5% among women with local stage disease to 10.5% among women with advanced disease. Among cases diagnosed with local disease, risk factors for the development of VTE within 1 year in localized disease included major surgery (hazard ratio [HR]=2.1, P<0.01), presence of long-term comorbidities (HR=2.9 for ≥3 comorbidities, P<0.0001), black race (HR=2.0, P<0.006), and sarcoma histology (HR=1.7, P<0.04). Among cases with regional disease, presence of comorbidities, black race, and sarcomas or nonendometrioid carcinomas were all associated with significantly higher risk of VTE. In advanced disease, the presence of any comorbidities and black race were the strongest predictors (HR=2.4 and 1.9, respectively). Women (aged<45 years) with advanced disease had a notably high 2-year incidence of 18%. Age did not predict VTE in localized and regional diseases. For all stages of cancer, development of VTE within 2 years was a significant predictor of decreased survival, and the magnitude of the risk was greatest among the cases diagnosed with localized disease (HR=6.1; confidence interval, 4.6-8.1). CONCLUSIONS: The incidence of VTE in women with uterine cancer was high, particularly in younger women with metastatic disease. The strong association between development of VTE and death suggests a close coupling between the biological aggressiveness of the cancer and the activation of thrombosis.

Well-defined, reversible disulfide cross-linked micelles for on-demand paclitaxel delivery.

To minimize premature release of drugs from their carriers during circulation in the blood stream, we have recently developed reversible disulfide cross-linked micelles (DCMs) that can be triggered to release drug at the tumor site or in cancer cells. We designed and synthesized thiolated linear-dendritic polymers (telodendrimers) by introducing cysteines to the dendritic oligo-lysine backbone of our previously reported telodendrimers comprised of linear polyethylene glycol (PEG) and a dendritic cluster of cholic acids. Reversibly cross-linked micelles were then prepared by the oxidization of thiol groups to disulfide bond in the core of micelles after the self-assembly of thiolated telodendrimers. The DCMs were spherical with a uniform size of 28 nm, and were able to load paclitaxel (PTX) in the core with superior loading capacity up to 35.5% (w/w, drug/micelle). Cross-linking of the micelles within the core reduced their apparent critical micelle concentration and greatly enhanced their stability in non-reductive physiological conditions as well as severe micelle-disrupting conditions. The release of PTX from the DCMs was significantly slower than that from non-cross-linked micelles (NCMs), but can be gradually facilitated by increasing the concentration of reducing agent (glutathione) to an intracellular reductive level. The DCMs demonstrated a longer in vivo blood circulation time, less hemolytic activities, and superior toxicity profiles in nude mice, when compared to NCMs. DCMs were found to be able to preferentially accumulate at the tumor site in nude mice bearing SKOV-3 ovarian cancer xenograft. We also demonstrated that the disulfide cross-linked micellar formulation of PTX (PTX-DCMs) was more efficacious than both free drug and the non-cross-linked formulation of PTX at equivalent doses of PTX in the ovarian cancer xenograft mouse model. The anti-tumor effect of PTX-DCMs can be further enhanced by triggering the release of PTX on-demand by the administration of the FDA approved reducing agent, N-acetylcysteine, after PTX-DCMs have reached the tumor site.

The effect of surface charge on in vivo biodistribution of PEG-oligocholic acid based micellar nanoparticles.

To systematically elucidate the effect of surface charge on the cellular uptake and in vivo fate of PEG-oligocholic acid based micellar nanoparticles (NPs), the distal PEG termini of monomeric PEG-oligocholic acid dendrimers (telodendrimers) are each derivatized with different number (n = 0, 1, 3 and 6) of anionic aspartic acids (negative charge) or cationic lysines (positive charge). Under aqueous condition, these telodendrimers self-assemble to form a series of micellar NPs with various surface charges, but with similar particle sizes. NPs with high surface charge, either positive or negative, were taken up more efficiently by RAW 264.7 murine macrophages after opsonization in fresh mouse serum. Mechanistic studies of cellular uptake of NPs indicated that several distinct endocytic pathways (e.g., clathrin-mediated endocytosis, caveolae-mediated endocytosis, and macropinocytosis) were involved in the cellular uptake process. After their cellular uptake, the majority of NPs were found to localize in the lysosome. Positively charged NPs exhibited dose-dependent hemolytic activities and cytotoxicities against RAW 264.7 cells proportional to the positive surface charge densities; whereas negatively charged NPs did not show obvious hemolytic and cytotoxic properties. In vivo biodistribution studies demonstrated that undesirable liver uptake was very high for highly positively or negatively charged NPs, which is likely due to active phagocytosis by macrophages (Kupffer cells) in the liver. In contrast, liver uptake was very low but tumor uptake was very high when the surface charge of NPs was slightly negative. Based on these studies, we can conclude that slightly negative charge may be introduced to the NPs surface to reduce the undesirable clearance by the reticuloendothelial system (RES) such as liver, improve the blood compatibility, thus deliver the anti-cancer drugs more efficiently to the tumor sites.