SOX8 Affects Tumoral SPARC Expression by Regulating EZH2 to Attenuate Effectiveness of albumin-bound paclitaxel in PDAC.

Pancreatic cancer is a dismal malignancy with poor prognosis. In spite of progress in surgical technology, chemotherapy is still the cornerstone in the multi-disciplinary treatment. Albumin-bound paclitaxel is a first-line treatment for PDAC patients. Yet the response rate of the drug is far from satisfying. SOX8 is a member of the sex determining region Y-boxes family, which is potentially related to the chemoresistance of tumor. Patient with high expression of SOX8 were insensitive to albumin-bound paclitaxel. SOX8 reduced apoptosis and G2/M cell cycle arrest caused by albumin-bound paclitaxel. SOX8 transcriptionally regulated EZH2, which reduced expression of SPARC by promoting the methylation of SPARC, thereby reducing the transport of albumin-bound paclitaxel in pancreatic cancer cells. EZH2 inhibitor, UNC1999, can reverse the effect of SOX8 on chemo-resistance of albumin-bound paclitaxel. Collectively, our data revealed SOX8/EZH2/SPARC signaling induced primary chemo-resistance of albumin-bound paclitaxel in pancreatic ductal adenocarcinoma.

A novel preparative method for nanoparticle albumin-bound paclitaxel with high drug loading and its evaluation both in vitro and in vivo.

We developed a novel preparative method for nanoparticle albumin-bound (nab) paclitaxel with high drug loading, which was based on improved paclitaxel solubility in polyethylene glycol (PEG) and self-assembly of paclitaxel in PEG with albumin powders into nanoparticles. That is, paclitaxel and PEG were firstly dissolved in ethanol, which was subsequently evaporated under vacuum. The obtained liquid was then mixed with human serum albumin powders. Thereafter, the mixtures were added into phosphate-buffered saline and nab paclitaxel suspensions emerged after ultrasound. Nab paclitaxel was finally acquired after dialysis and freeze drying. The drug loading of about 15% (W/V) were realized in self-made nab paclitaxel, which was increased by approximately 50% compared to 10% (W/V) in Abraxane. Now this new preparative method has been authorized to obtain patent from China and Japan. The similar characteristics of self-made nab paclitaxel compared to Abraxane were observed in morphology, encapsulation efficiency, in vitro release, X-ray diffraction analysis, differential scanning calorimetry analysis, and circular dichroism spectra analysis. Consistent concentration-time curves in rats, biodistributions in mice, anti-tumor activities in mice, and histological transmutation in mice were also found between Abraxane and self-made nanoparticles. In a word, our novel preparative method for nab paclitaxel can significantly improve drug loading, obviously decrease product cost, and is considered to have potent practical value.

A Comparative In Vivo Study of Albumin-Coated Paclitaxel Nanocrystals and Abraxane.

Nanoparticulate drug carriers exploit the enhanced permeability of tumor vasculature to achieve selective delivery of chemotherapeutic drugs. For this purpose, nanoparticles (NPs) need to circulate with a long half-life, enter tumors via the permeable vasculature and stay in tumors via favorable interactions with tumor cells. To fulfill these requirements, albumin-coated nanocrystal formulation of paclitaxel (PTX), Cim-F-alb, featuring high drug loading content, physical stability in serum, and surface-bound albumin in its native conformation is prepared. The pharmacokinetic and biodistribution (PK/BD) profiles of Cim-F-alb in a mouse model of B16F10 melanoma show that Cim-F-alb exhibits a longer plasma half-life and a greater PTX deposition in tumors than Abraxane by ≈1.5 and ≈4.6 fold, respectively. Biolayer interferometry analysis indicates that Cim-F-alb has less interaction with serum proteins than nanocrystals lacking albumin coating, indicating the protective effect of the surface-bound albumin against opsonization in the initial deposition phase. With the advantageous PK/BD profiles, Cim-F-alb shows greater and longer-lasting anticancer efficacy than Abraxane at the equivalent dose. This study demonstrates the significance of controlling circulation stability and surface property of NPs in efficient drug delivery to tumors and enhanced anticancer efficacy.

Pharmacokinetics and safety of paclitaxel delivery into porcine airway walls by a new endobronchial drug delivery catheter.

BACKGROUND AND OBJECTIVE: Intratumoral administration of chemotherapeutic agents is a treatment modality that has proven efficacious in reducing the recurrence of tumours and increases specificity of treatment while minimizing systemic side effects. Direct intratumoral injection of malignant airway obstruction has potential therapeutic benefits but tissue drug concentrations and side-effect profiles are poorly understood. METHODS: Bronchial wall injection of generic paclitaxel (PTX) (102 injections of 0.05, 0.5, 1.5 or 2.5 mg/mL in 10 healthy pigs), saline (14 injections in 2 healthy pigs) or Abraxane (ABX) (24 injections of 0.5 mg/mL in 4 healthy pigs) was performed with a microneedle infusion catheter. Local histopathology, plasma and tissue PTX concentrations were evaluated at 7, 20 or 28 days post-injection. RESULTS: Injection of generic PTX directly into the bronchial wall at doses up to 1.5 mg/mL only caused minimal tissue injury. Dose-limiting tissue reaction was observed at 2.5 mg/mL. Plasma PTX was detectable for up to 5 days but not at 28 days, with area under the curve (AUC)(0-5d) 20- to 50-fold lower than the AUC(0-∞) of 6300 ng h/mL for the approved intravenous dose. At 7 and 28 days post-injection, bronchial PTX tissue concentrations were above a 10-nmol/L cancer therapeutic level. PTX was not found in peripheral tissues. Similar results were observed between ABX and generic PTX. CONCLUSION: Results of these studies confirm the administration of PTX directly into the bronchial wall is safe and feasible. PTX was detectable in plasma for <7 days but tissue concentrations remained therapeutic throughout the follow-up period.

Gemcitabine enhances the transport of nanovector-albumin-bound paclitaxel in gemcitabine-resistant pancreatic ductal adenocarcinoma.

The mechanism for improved therapeutic efficacy of the combination therapy with nanoparticle albumin-bound paclitaxel (nAb-PTX) and gemcitabine (gem) for pancreatic ductal adenocarcinoma (PDAC) has been ascribed to enhanced gem transport by nAb-PTX. Here, we used an orthotopic mouse model of gem-resistant human PDAC in which increasing gem transport would not improve the efficacy, thus revealing the importance of nAb-PTX transport. We aimed to evaluate therapeutic outcomes and transport of nAb-PTX to PDAC as a result of (1) encapsulating nAb-PTX in multistage nanovectors (MSV); (2) effect of gem on caveolin-1 expression. Treatment with MSV/nAb-PTX + gem was highly efficient in prolonging animal survival in comparison to other therapeutic regimens. MSV/nAb-PTX + gem also caused a substantial increase in tumor PTX accumulation, significantly reduced tumor growth and tumor cell proliferation, and increased apoptosis. Moreover, gem enhanced caveolin-1 expression in vitro and in vivo, thereby improving transport of nAb-PTX to PDAC. This data was confirmed by analysis of PDACs from patients who received gem-based neo-adjuvant chemotherapy. In conclusion, we found that nAb-PTX treatment of gem-resistant PDAC can be enhanced by (1) gem through up-regulation of caveolin-1 and (2) MSV through increasing accumulation of nAb-PTX in the tumor.

Layer-by-layer assembly of hierarchical nanoarchitectures to enhance the systemic performance of nanoparticle albumin-bound paclitaxel.

Although protein-bound paclitaxel (PTX, Abraxane®) has been established as a standard PTX-based therapy against multiple cancers, its clinical success is limited by unfavorable pharmacokinetics, suboptimal biodistribution, and acute toxicities. In the present study, we aimed to apply the principles of a layer-by-layer (LbL) technique to improve the poor colloidal stability and pharmacokinetic pattern of nanoparticle albumin-bound paclitaxel (nab-PTX). LbL-based nab-PTX was successfully fabricated by the alternate deposition of polyarginine (pARG) and poly(ethylene glycol)-block-poly (L-aspartic acid) (PEG-b-PLD) onto an albumin conjugate. The presence of protective entanglement by polyamino acids prevented the dissociation of nab-PTX and improved its colloidal stability even at a 100-fold dilution. The combined effect of high nanoparticle internalization and controlled release of PTX from LbL-nab-PTX increased its cytotoxicity in MCF-7 and MDA-MB-231 breast cancer cells. LbL-nab-PTX consistently induced apoptosis in approximately 52% and 22% of MCF-7 and MDA-MB-231 cancer cells, respectively. LbL assembly of polypeptides effectively prevented exposure of PTX to the systemic environment and thereby inhibited drug-induced hemolysis. Most importantly, LbL assembly of polypeptides to nab-PTX effectively increased the blood circulation potential of PTX and improved therapeutic efficacy via a significantly higher area under the curve (AUC)0-∞. We report for the first time the application of LbL functional architectures for improving the systemic performance of nab-PTX with a view toward its clinical translation for cancer therapy.

Non-specific binding and steric hindrance thresholds for penetration of particulate drug carriers within tumor tissue.

Therapeutic nanoparticles (NPs) approved for clinical use in solid tumor therapy provide only modest improvements in patient survival, in part due to physiological barriers that limit delivery of the particles throughout the entire tumor. Here, we explore the thresholds for NP size and surface poly(ethylene glycol) (PEG) density for penetration within tumor tissue extracellular matrix (ECM). We found that NPs as large as 62nm, but less than 110nm in diameter, diffused rapidly within a tumor ECM preparation (Matrigel) and breast tumor xenograft slices ex vivo. Studies of PEG-density revealed that increasing PEG density enhanced NP diffusion and that PEG density below a critical value led to adhesion of NP to ECM. Non-specific binding of NPs to tumor ECM components was assessed by surface plasmon resonance (SPR), which revealed excellent correlation with the particle diffusion results. Intravital microscopy of NP spread in breast tumor tissue confirmed a significant difference in tumor tissue penetration between the 62 and 110nm PEG-coated NPs, as well as between PEG-coated and uncoated NPs. SPR assays also revealed that Abraxane, an FDA-approved non-PEGylated NP formulation used for cancer therapy, binds to tumor ECM. Our results establish limitations on the size and surface PEG density parameters required to achieve uniform and broad dispersion within tumor tissue and highlight the utility of SPR as a high throughput method to screen NPs for tumor penetration.

Redirecting Transport of Nanoparticle Albumin-Bound Paclitaxel to Macrophages Enhances Therapeutic Efficacy against Liver Metastases.

Current treatments for liver metastases arising from primary breast and lung cancers are minimally effective. One reason for this unfavorable outcome is that liver metastases are poorly vascularized, limiting the ability to deliver therapeutics from the systemic circulation to lesions. Seeking to enhance transport of agents into the tumor microenvironment, we designed a system in which nanoparticle albumin-bound paclitaxel (nAb-PTX) is loaded into a nanoporous solid multistage nanovector (MSV) to enable the passage of the drug through the tumor vessel wall and enhance its interaction with liver macrophages. MSV enablement increased nAb-PTX efficacy and survival in mouse models of breast and lung liver metastasis. MSV-nAb-PTX also augmented the accumulation of paclitaxel and MSV in the liver, specifically in macrophages, whereas paclitaxel levels in the blood were unchanged after administering MSV-nAb-PTX or nAb-PTX. In vitro studies demonstrated that macrophages treated with MSV-nAb-PTX remained viable and were able to internalize, retain, and release significantly higher quantities of paclitaxel compared with treatment with nAb-PTX. The cytotoxic potency of the released paclitaxel was also confirmed in tumor cells cultured with the supernatants of macrophage treated with MSV-nAB-PTX. Collectively, our findings showed how redirecting nAb-PTX to liver macrophages within the tumor microenvironment can elicit a greater therapeutic response in patients with metastatic liver cancer, without increasing systemic side effects.