Pharmacological effects of 5-fluorouracil microspheres on peritoneal carcinomatosis in animals

Tumor Penetrating Theranostic Nanoparticles for Enhancement of Targeted and Image-guided Drug Delivery into Peritoneal Tumors following Intraperitoneal Delivery

The major obstacles in intraperitoneal (i.p.) chemotherapy of peritoneal tumors are fast absorption of drugs into the blood circulation, local and systemic toxicities, inadequate drug penetration into large tumors, and drug resistance. Targeted theranostic nanoparticles offer an opportunity to enhance the efficacy of i.p. therapy by increasing intratumoral drug delivery to overcome resistance, mediating image-guided drug delivery, and reducing systemic toxicity. Herein we report that i.p. delivery of urokinase plasminogen activator receptor (uPAR) targeted magnetic iron oxide nanoparticles (IONPs) led to intratumoral accumulation of 17% of total injected nanoparticles in an orthotopic mouse pancreatic cancer model, which was three-fold higher compared with intravenous delivery. Targeted delivery of near infrared dye labeled IONPs into orthotopic tumors could be detected by non-invasive optical and magnetic resonance imaging. Histological analysis revealed that a high level of uPAR targeted, PEGylated IONPs efficiently penetrated into both the peripheral and central tumor areas in the primary tumor as well as peritoneal metastatic tumor. Improved theranostic IONP delivery into the tumor center was not mediated by nonspecific macrophage uptake and was independent from tumor blood vessel locations. Importantly, i.p. delivery of uPAR targeted theranostic IONPs carrying chemotherapeutics, cisplatin or doxorubicin, significantly inhibited the growth of pancreatic tumors without apparent systemic toxicity. The levels of proliferating tumor cells and tumor vessels in tumors treated with the above theranostic IONPs were also markedly decreased. The detection of strong optical signals in residual tumors following i.p. therapy suggested the feasibility of image-guided surgery to remove drug-resistant tumors. Therefore, our results support the translational development of i.p. delivery of uPAR-targeted theranostic IONPs for image-guided treatment of peritoneal tumors.

Improving paclitaxel pharmacokinetics by using tumor-specific mesoporous silica nanoparticles with intraperitoneal delivery

Mesoporous silica nanoparticles (MSNs) containing paclitaxel for intraperitoneal (i.p.) delivery were developed to exploit the tumor specific accumulation of these nanocarriers after i.p. injection and the slow release of paclitaxel from the MSNs. A 3.5-fold increase in tumor cellular drug uptake was observed for the paclitaxel-loaded MSNs compared with free paclitaxel. An in vivo study using xenograft mice bearing peritoneal human pancreatic carcinoma MIA PaCa-2 demonstrated that the MSN-paclitaxel formulation, compared to free paclitaxel, exhibited a 3.2-fold increase in peritoneal cavity residence time, slower absorption into the systemic circulation with one third systemic exposure, but a 6.5-fold increase in peritoneal tumor accumulation. Tissue distribution imaging showed significantly greater accumulation of fluorescent MSNs in tumor tissues compared to other peritoneal tissues. In conclusion, intraperitoneal administration of drug-containing MSNs was effective at reducing systemic exposure and increasing the peritoneal tumor accumulation of paclitaxel.

Versatility of Particulate Carriers: Development of Pharmacodynamically Optimized Drug-Loaded Microparticles for Treatment of Peritoneal Cancer

Intraperitoneal (IP) chemotherapy confers significant survival benefits in cancer patients. However, several problems, including local toxicity and ineffectiveness against bulky tumors, have prohibited it from becoming a standard-of-care. We have developed drug-loaded, tumor-penetrating microparticles (TPM) to address these problems. TPM comprises two components and uses the versatile PLGA or poly(lacticco-glycolic acid) copolymer to provide tumor-selective adherence and pharmacodynamically optimized fractionated dosing to achieve the desired tumor priming (which promotes particle penetration into tumors) plus immediate and sustained antitumor activity. Preclinical studies show that TPM is less toxic and more effective against several IP metastatic tumors with different characteristics (fast vs. slow growing, porous vs. densely packed structures, wide-spread vs. solitary tumors, early vs. late stage, with or without peritoneal carcinomatosis or ascites), compared to the intravenous paclitaxel/Cremophor micellar solution that has been used off-label in previous IP studies. TPM further requires less frequent dosing. These encouraging preclinical results have motivated the follow-up clinical development of TPM. We are working with National Institutes of Health on the IND-enabling studies.

Treatment and prevention of peritoneal carcinomatosis from gastric cancer by cytoreductive surgery and hyperthermic intraperitoneal chemotherapy: overview and rationale

Peritoneal carcinomatosis (PC) from gastric cancer is a condition with a very bleak prognosis. Most authors consider it to be a terminal disease and recommend palliative therapy only. Multimodal therapeutic approaches to PC have emerged in the last decades, combining cytoreductive surgery (CRS) and peritonectomy procedures with perioperative intraperitoneal chemotherapy (IPEC), including hyperthermic intraperitoneal chemotherapy (HIPEC) and/or early postoperative intraperitoneal chemotherapy (EPIC). We reviewed the pertinent literature concerning the HIPEC modality both for the treatment of established PC and the prevention of peritoneal recurrence after potentially curative gastric cancer (GC) surgery. Basically, the two procedures relate to different aspects of GC and they are not comparable, since the latter has been used as an adjuvant when PC is still not macroscopically evident and the former has been exclusively used in advanced gastric cancer stages with peritoneal dissemination. Data supporting beneficial effects once gastric PC is already manifest is scarce and limited to few centres with specific experience in this field. Conversely, with regards to the peritoneal perfusion for preventing PC in high risk gastric cancer patients, there are phase III trials and meta-analysis which support beneficial effects resulting from the HIPEC procedure. To offer a baseline guide, we summarized the actual status and general outcome obtained by this multimodal technique, in association or not with CRS as treatment of advanced GC.

Intraperitoneal therapy for peritoneal cancer

Cancers originating from organs in the peritoneal cavity (e.g., ovarian, pancreatic, colorectal, gastric and liver) account for approximately 250,000 new cancer cases annually in the USA. Peritoneal metastases are common owing to locoregional spread and distant metastases of extraperitoneal cancers. A logical treatment is intraperitoneal therapy, as multiple studies have shown significant targeting advantage for this treatment, including significant survival benefits in stage III, surgically debulked ovarian cancer patients. However, the clinical use of intraperitoneal therapy has been limited, in part, by toxicity, owing to the use of indwelling catheters or high drug exposure, by inadequate drug penetration into bulky tumors (>1 cm) and by the lack of products specifically designed and approved for intraperitoneal treatments. This article provides an overview on the background of peritoneal metastasis, clinical research on intraperitoneal therapy, the pharmacokinetic basis of drug delivery in intraperitoneal therapy and our development of drug-loaded tumor-penetrating microparticles.

CD44-targeted microparticles for delivery of cisplatin to peritoneal metastases

Intraperitoneal (ip) chemotherapy increases the survival of optimally debulked patients with ovarian cancer due to direct access of the drug to tumor nodules growing on the peritoneal surface. CD44 is overexpressed in many ovarian cancers. To further improve efficacy, we sought to develop a cisplatin-loaded microparticle that would target to CD44 on cancer cells when injected ip. Hyplat microparticles were produced by cross-linking hyaluronan via its carboxylate groups with cisplatin at a high temperature. Hyplat particles had an average diameter of 580 nm, and cisplatin was incorporated with an efficiency of approximately 50%. Drug release varied with chloride concentration but not pH. Flow cytometric analysis and confocal microscopy confirmed that CD44 positive cells (OV2008, A2780) internalized Hyplat more efficiently than CD44 negative cells (UCI101); uptake was compromised by knocking down CD44 expression. Clearance of Hyplat from the mouse peritoneum was reduced by 7-fold and tumor uptake was increased by 2- to 3-fold in CD44-positive but not CD44-negative tumor models compared to that attained with free cisplatin. Hyplat was more effective than cisplatin at slowing the growth of intraperitoneally inoculated A2780 ovarian cancer cells and improving survival thus demonstrating the potential of Hyplat to enhance the efficacy of ip chemotherapy.

Novel strategies to improve the anticancer action of 5-fluorouracil by using drug delivery systems

Because of the fundamental importance of new therapeutic routes for cancer treatment, a number of systems based on colloidal particles as vehicles for the delivery of the anticancer drug 5-fluorouracil have been devised. The target is always to provide the proper dose of the antitumor agent only at the desired locus of action, thus reducing the unwanted side effects. In this review, the main strategies and the more significant results in the development of 5-fluorouracil carriers for cancer treatment are discussed.

Effects of carrier on disposition and antitumor activity of intraperitoneal Paclitaxel

PURPOSE

The rationale for intraperitoneal (IP) chemotherapy is to expose peritoneal tumors to high drug concentrations. While multiple phase III trials have established the significant survival advantage by adding IP therapy to intravenous therapy in optimally debulked ovarian cancer patients, the use of IP chemotherapy is limited by the complications associated with indwelling catheters and by the local chemotherapy-related toxicity. The present study evaluated the effects of drug carrier on the disposition and efficacy of IP paclitaxel, for identifying strategies for further development of IP treatment.

MATERIALS AND METHODS

Three paclitaxel formulations, i.e., Cremophor micelles, Cremophor-free paclitaxel-loaded gelatin nanoparticles and polymeric microparticles, were evaluated for peritoneal targeting advantage and antitumor activity in mice after IP injection. Whole body autoradiography and scanning electron microscopy were used to visualize the spatial drug distribution in tissues. A kinetic model, depicting the multiple processes involved in the peritoneal-to-plasma transfer of paclitaxel and its carriers, was established to determine the mechanisms by which a drug carrier alters the peritoneal targeting advantage.

RESULTS

Autoradiographic results indicated that IP injection yielded much higher paclitaxel concentrations in intestinal tissues relative to intravenous injection. Compared to the Cremophor and nanoparticle formulations, the microparticles showed slower drug clearance from the peritoneal cavity, slower absorption into the systemic circulation, longer residence time, 10- to 45-times greater peritoneal targeting advantage and approximately 2-times longer increase in survival time (p < 0.01 for all parameters).

CONCLUSIONS

Our results indicate the important roles of drug carrier in determining the peritoneal targeting advantage and antitumor activity of IP treatment.

Co-delivery of an antisense oligonucleotide and 5-fluorouracil using sustained release poly (lactide-co-glycolide) microsphere formulations for potential combination therapy in cancer

Antisense oligonucleotides (AODNs) can selectively inhibit oncogene expression by Watson-Crick hybridisation to target mRNA and are being increasingly considered for use in combination with conventional drugs for potential anticancer therapy. Combination therapy of AODNs and cytotoxic agents using biodegradable polymeric delivery systems potentially offers several advantages including site-specific or organ-directed targeting, protection from digesting enzymes, and improved pharmacokinetics/pharmacodynamics resulting from sustained delivery of the entrapped drugs. Using a model AODN targeting the epidermal growth factor receptor (that is over-expressed in several cancers including breast and brain cancer) and the commonly used cytotoxic agent, 5-fluorouracil (5-FU), we have examined the use of poly (lactide-co-glycolide) (P(LA-GA)) microsphere formulations for co-delivery of these agents. Both agents were either co-entrapped in a single microsphere formulation or individually entrapped in two separate microsphere formulations and release profiles determined in vitro. Using a double emulsion method for preparing the P(LA-GA) microspheres suitable entrapment and sustained release over 35 days was observed in both types of formulation. Release of AODN and 5-FU from all formulations appeared to be biphasic. However, the release rates of the two agents were significantly slower when co-entrapped as a single microsphere formulation compared to those obtained with the separate formulations. Electrophoretic mobility shift assays suggested that this might be, in part, due to an interaction of 5-FU with the oligodeoxynucleotide (ODN). Further, our data suggest that by mixing individual formulations of 5-FU and ODNs at different mass ratios allowed greater flexibility in achieving the desired release profile as well as avoiding potential drug-drug interactions. Thus, co-administration of individual P(LA-GA) microsphere formulations of AODNs and 5-FU, at appropriate mass ratios, appears worthy of further investigation for the potential co-delivery of these anti-cancer agents in vivo.

Effect of viscous additives on drug absorption from the liver surface in rats using phenol red as a model

The purpose of this study is to obtain information that can be used to improve controlled release and residence time of drugs on the liver surface. Using carboxymethylcellulose sodium salt (CMC-Na) and polyvinyl alcohol (PVA), we examined the effect of viscous formulations on the absorption of phenol red as a model. In the presence of 3% CMC-Na or 15% PVA, the maximum plasma concentration of phenol red decreased after application to the rat liver surface using a cylindrical glass cell. The absorption ratios in 6 h calculated from the remaining amount of phenol red in the glass cell were 68.6, 60.5 and 48.7% (control: 73.1%) in the presence of 1 or 3% CMC-Na and 15% PVA, respectively. As a result of the reduction in the absorption ratio, the amount of phenol red excreted into the bile and urine in 6 h was decreased by the addition of the viscous additives. The decrease in absorption rate was characterized by a pharmacokinetic analysis of the plasma concentration profile. The change in absorption rate differed between the viscous additives, reflecting the result of the in vitro release experiment. Accordingly, the possibility that the drug absorption rate from the liver surface can be altered by viscous additives was suggested to have a promising prospect for therapeutic use.

Effect of application volume and area on the absorption of phenol red, as a model drug, from the liver surface in rats

To determine the influence of the method of administration of a pharmaceutical formulation we have examined the importance of application volume and area in the absorption of phenol red, as a model drug, from the rat-liver surface. When 1 mg phenol red was applied to the rat-liver surface, in-vivo, in three volumes (0.1, 0.2 or 0.334 mL) using a cylindrical glass cell (i.d. 9 mm), the shape of the plasma concentration profile differed greatly, particularly the maximum concentration. These patterns were well fitted by a two-compartment model with first-order absorption, and the absorption-rate constant Ka obtained was inversely proportional to the application volume. The absorption ratio and biliary recovery of phenol red after 6 h increased with glass cell area (i.d. 6, 9 or 14 mm; area 0.28, 0.64 or 1.54 cm2). Furthermore, the permeability coefficient Papp derived from Ka did not depend on application area, indicating no difference in the absorption characteristics of the liver surface. This also implies transport of the drug by passive diffusion from the liver surface. After intraperitoneal administration to the rat-liver surface for clinical application, increasing the application volume resulted in the delayed disappearance of phenol red from the plasma. However, the difference was not as marked as that obtained by use of the glass cell. The assumption that the effective area relating to the absorption changed with the application volume enabled us to estimate Papp. Consequently, we speculate that absorbability can be estimated precisely by consideration of application volume and area.