Increased Enzyme Loading in PICsomes via Controlling Membrane Permeability Improves Enzyme Prodrug Cancer Therapy Outcome.

Mesoscopic-sized polyion complex vesicles (PICsomes) with semi-permeable membranes are promising nanoreactors for enzyme prodrug therapy (EPT), mainly due to their ability to accommodate enzymes in their inner cavity. Increased loading efficacy and retained activity of enzymes in PICsomes are crucial for their practical application. Herein, a novel preparation method for enzyme-loaded PICsomes, the stepwise crosslinking (SWCL) method, was developed to achieve both high feed-to-loading enzyme efficiency and high enzymatic activity under in vivo conditions. Cytosine deaminase (CD), which catalyzes the conversion of the 5-fluorocytosine (5-FC) prodrug to cytotoxic 5-fluorouracil (5-FU), was loaded into PICsomes. The SWCL strategy enabled a substantial increase in CD encapsulation efficiency, up to ~44% of the feeding amount. CD-loaded PICsomes (CD@PICsomes) showed prolonged blood circulation to achieve appreciable tumor accumulation via enhanced permeability and retention effect. The combination of CD@PICsomes and 5-FC produced superior antitumor activity in a subcutaneous model of C26 murine colon adenocarcinoma, even at a lower dose than systemic 5-FU treatment, and showed significantly reduced adverse effects. These results reveal the feasibility of PICsome-based EPT as a novel, highly efficient, and safe cancer treatment modality.

Facile Preparation of Delivery Platform of Water-Soluble Low-Molecular-Weight Drugs Based on Polyion Complex Vesicle (PICsome) Encapsulating Mesoporous Silica Nanoparticle.

Polyion complex vesicles (PICsomes) are polymeric hollow capsules composed of a unique semipermeable membrane, which may represent a versatile platform for constructing drug-loaded nanoformulation. However, it is difficult to retain water-soluble low-molecular-weight compounds (LMWCs) in the inner space of PICsome because of the high permeability of PIC membrane for LMWCs. Herein, we selected mesoporous silica nanoparticle (MSN) as a drug-retaining nanomatrix, and we demonstrated successful encapsulation of MSN into the PICsome to obtain MSN@PICsome. The efficacy of MSN loading, a ratio of the amount of MSN encapsulated in the PICsome to the amount of feed MSN, was at most 83%, and the diameter of resulting product was approximately 100 nm. The obtained MSN@PICsome was stably dispersed under the physiological condition, and showed considerable longevity in blood circulation of mice. Furthermore, the surface of MSN in MSN@PICsome can be modified without any deterioration of the vesicle structure, obtaining amino-functionalized and sulfonate-functionalized MSN@PICsomes (A-MSN@PICsome and S-MSN@PICsome, respectively). Both surface-modified MSN@PICsomes were successfully loaded with charged water-soluble low-molecular-weight compounds (LMWCs). Particularly, S-MSN@PICsome kept 8 wt % gemcitabine (GEM) per S-MSN, and released it in a sustained manner. GEM-loaded S-MSN@PICsome demonstrated marked cytotoxicity against cultured tumor cells, and achieved significant in vivo efficacy to suppress the growth of subcutaneously implanted lung tumor via intravenous administration.

[Pathological complete response in 2 patients with cT4 esophageal cancer treated with neoadjuvant chemoradiation therapy].

We report the cases of 2 patients with clinical T4( cT4) esophageal cancer who achieved pathological complete response on treatment with neoadjuvant chemoradiation therapy. Case 1 involved a 68-year-old woman who was diagnosed as having cT4 advanced esophageal cancer( with involvement of the aorta and left pulmonary vein). Neoadjuvant chemoradiation therapy with 5-fluorouraci(l 5-FU)( 800 mg/m2, days 1-5 and days 29-33), cisplatin( CDDP 80 mg/m2, days 1 and 29), and radiation (39.6 Gy/22 Fr) was administered, and the tumor showed a partial response (PR). Case 2 involved a 69-year-old man who was diagnosed as having cT4 advanced esophageal cancer( with involvement of the main bronchus). Neoadjuvant chemoradiation therapy with 5-FU( 800 mg/m2, days 1-5 and days 29-33), CDDP( 80 mg/m2, days 1 and 29), and radiation( 39.6 Gy/22 Fr) was administered, and the tumor showed a clinical PR. After tumor response was noted, curative esophagectomy was performed in both cases, without any complications, and a pathological complete response was achieved in both patients.

Properties of gastroretentive sustained release tablets prepared by combination of melt/sublimation actions of L-menthol and penetration of molten polymers into tablets.

A novel floating sustained release tablet having a cavity in the center was developed by utilizing the physicochemical properties of L-menthol and the penetration of molten hydrophobic polymer into tablets. A dry-coated tablet containing famotidine as a model drug in outer layer was prepared with a L-menthol core by direct compression. The tablet was placed in an oven at 80°C to remove the L-menthol core from tablet. The resulting tablet was then immersed in the molten hydrophobic polymers at 90°C. The buoyancy and drug release properties of tablets were investigated using United States Pharmacopeia (USP) 32 Apparatus 2 (paddle 100 rpm) and 900 ml of 0.01 N HCl. The L-menthol core in tablets disappeared completely through pathways in the outer layer with no drug outflows when placed in an oven for 90 min, resulting in a formation of a hollow tablet. The hollow tablets floated on the dissolution media for a short time and the drug release was rapid due to the disintegration of tablet. When the hollow tablets were immersed in molten hydrophobic polymers for 1 min, the rapid drug release was drastically retarded due to a formation of wax matrices within the shell of tablets and the tablets floated on the media for at least 6 h. When Lubri wax® was used as a polymer, the tablets showed the slowest sustained release. On the other hand, faster sustained release properties were obtained by using glyceryl monostearate (GMS) due to its low hydrophobic nature. The results obtained in this study suggested that the drug release rate from floating tablets could be controlled by both the choice of hydrophobic polymer and the combined use of hydrophobic polymers.