Soliman M. Formulation, Development and Evaluation of Ibuprofen Loaded Nano-transferosomal Gel for the Treatment of Psoriasis

The present work was aimed to develop a transferosomal gel of ibuprofen (IBU) for the amelioration of psoriasis like inflammation. Three formulation of IBU loaded transferosomes (TFs1-TFs3) were prepared using different proportions of lipid (phospholipon 90H) and surfactant (tween 80) and further evaluated for vesicle size, zeta potential (ZP), entrapment efficiency and in vitro drug release. The IBU loaded transferosomes (TFs2) was optimized with vesicle size (217±8.4 nm), PDI (0.102), ZP (-31.5±4.3 mV), entrapment efficiency (88.4±6.9%) and drug loading (44.2±2.9%). Further, the optimized IBU loaded transferosomes (TFs2) was incorporated into 1% carbopol 934 gel base and characterized for homogeneity, extrudability, viscosity and drug content. The in vivo pharmacodynamic study of gel exhibited reduction in psoriasis like inflammation in mice. The ibuprofen loaded transferosomal gel was successfully developed and has shown the potential to be a new therapy against psoriasis like inflammation.

A simplified method for manufacturing RNAi therapeutics for local administration

RNA interference (RNAi) is one of the most promising strategies for cancer therapeutics. The successful translation of RNAi therapeutics to a clinic setting requires a delivery system that is efficient and simple to upscale. In this study, we devised a simple industrial method to manufacture lipoplex, which includes short hairpin RNA against the expression of thymidylate synthase (TS shRNA) - a key molecule for DNA biosynthesis. An aqueous solution of TS shRNA was gently mixed with either a precursor of cationic liposome (Presome DF-1) or a cationic lipid mixture in an o/w emulsion. This solution was subsequently lyophilized under optimal conditions to obtain either FD-lipoplex-1 or FD-lipoplex-2, respectively. With this method, a lipoplex in activated form was obtained via a simple "one-step" hydration with saline. Both forms of FD-lipoplex showed physicochemical properties comparable to those of conventional lipoplex. FD-lipoplexes stably retained TS shRNA within their formulations in the presence of tumor ascites fluid. Intraperitoneal treatment with either FD-lipoplex-1 or FD-lipoplex-2 provided a therapeutic level of efficacy comparable to that of conventional lipoplex in the treatment of a peritoneal disseminated gastric cancer mouse model. Collectively, established freeze-drying-based methods for RNAi-therapeutic preparation could realistically be used in a clinical setting for the treatment of patients with peritoneal disseminated cancer.

PEGylated liposomes: immunological responses

A commonly held view is that nanocarriers conjugated to polyethylene glycol (PEG) are non-immunogenic. However, many studies have reported that unexpected immune responses have occurred against PEG-conjugated nanocarriers. One unanticipated response is the rapid clearance of PEGylated nanocarriers upon repeat administration, called the accelerated blood clearance (ABC) phenomenon. ABC involves the production of antibodies toward nanocarrier components, including PEG, which reduces the safety and effectiveness of encapsulated therapeutic agents. Another immune response is the hypersensitivity or infusion reaction referred to as complement (C) activation-related pseudoallergy (CARPA). Such immunogenicity and adverse reactivities of PEGylated nanocarriers may be of potential concern for the clinical use of PEGylated therapeutics. Accordingly, screening of the immunogenicity and CARPA reactogenicity of nanocarrier-based therapeutics should be a prerequisite before they can proceed into clinical studies. This review presents PEGylated liposomes, immunogenicity of PEG, the ABC phenomenon, C activation and lipid-induced CARPA from a toxicological point of view, and also addresses the factors that influence these adverse interactions with the immune system.

Intratumoral Visualization of Oxaliplatin within a Liposomal Formulation Using X-ray Fluorescence Spectrometry

Microsynchrotron radiation X-ray fluorescence spectrometry (μ-SR-XRF) is an X-ray procedure that utilizes synchrotron radiation as an excitation source. μ-SR-XRF is a rapid, nondestructive technique that allows mapping and quantification of metals and biologically important elements in cell or tissue samples. Generally, the intratumor distribution of nanocarrier-based therapeutics is assessed by tracing the distribution of a labeled nanocarrier within tumor tissue, rather than by tracing the encapsulated drug. Instead of targeting the delivery vehicle, we employed μ-SR-XRF to visualize the intratumoral microdistribution of oxaliplatin (l-OHP) encapsulated within PEGylated liposomes. Tumor-bearing mice were intravenously injected with either l-OHP-containing PEGylated liposomes (l-OHP liposomes) or free l-OHP. The intratumor distribution of l-OHP within tumor sections was determined by detecting the fluorescence of platinum atoms, which are the main elemental components of l-OHP. The l-OHP in the liposomal formulation was localized near the tumor vessels and accumulated in tumors at concentrations greater than those seen with the free form, which is consistent with the results of our previous study that focused on fluorescent labeling of PEGylated liposomes. In addition, repeated administration of l-OHP liposomes substantially enhanced the tumor accumulation and/or intratumor distribution of a subsequent dose of l-OHP liposomes, presumably via improvements in tumor vascular permeability, which is also consistent with our previous results. In conclusion, μ-SR-XRF imaging efficiently and directly traced the intratumor distribution of the active pharmaceutical ingredient l-OHP encapsulated in liposomes within tumor tissue. μ-SR-XRF imaging could be a powerful means for estimating tissue distribution and even predicting the pharmacological effect of nanocarrier-based anticancer metal compounds.

Modulation of antitumor immunity contributes to the enhanced therapeutic efficacy of liposomal oxaliplatin in mouse model

Immune modulation of the tumor microenvironment has been reported to participate in the therapeutic efficacy of many chemotherapeutic agents. Recently, we reported that liposomal encapsulation of oxaliplatin (l-OHP) within PEGylated liposomes conferred a superior antitumor efficacy to free l-OHP in murine colorectal carcinoma-bearing mice through permitting preferential accumulation of the encapsulated drug within tumor tissue. However, the contribution of the immune-modulatory properties of liposomal l-OHP and/or free l-OHP to the overall antitumor efficacy was not elucidated. In the present study, therefore, we investigated the effect of liposomal encapsulation of l-OHP within PEGylated liposomes on the antitumor immunity in both immunocompetent and immunodeficient mice. Liposomal l-OHP significantly suppressed the growth of tumors implanted in immunocompetent mice, but not in immunodeficient mice. In immunocompetent mice, liposomal l-OHP increased the tumor MHC-1 level and preserved antitumor immunity through decreasing the number of immune suppressor cells, including regulatory T cells, myeloid-derived suppressor cells, and tumor-associated macrophages, which collectively suppress CD8⁺ T cell-mediated tumor cells killing. In contrast, free l-OHP ruined antitumor immunity. These results suggest that the antitumor efficacy of liposomal l-OHP is attributed, on the one hand, to its immunomodulatory effect on tumor immune microenvironment that is superior to that of free l-OHP, and on the other hand, to its direct cytotoxic effect on tumor cells.

Co-administration of liposomal l-OHP and PEGylated TS shRNA-lipoplex: A novel approach to enhance anti-tumor efficacy and reduce the immunogenic response to RNAi molecules

Many therapeutic strategies have been applied in efforts to conquer the development and/or progression of cancer. The combination of chemotherapy and an RNAi-based approach has proven to be an efficient anticancer therapy. However, the feasibility of such a therapeutic strategy has been substantially restricted either by the failure to achieve the efficient delivery of RNAi molecules to tumor tissue or by the immunostimulatory response triggered by RNAi molecules. In this study, therefore, we intended to investigate the efficacy of using liposomal oxaliplatin (liposomal l-OHP) to guarantee the efficient delivery of RNAi molecules, namely shRNA against thymidylate synthase (TS shRNA) complexed with cationic liposome (TS shRNA-lipoplex), to solid tumors, and to suppress the immunostimulatory effect of RNAi molecules, TS shRNA, following intravenous administration. Herein, we describe how liposomal l-OHP enhanced the intra-tumor accumulation of TS shRNA-lipoplex and significantly reduced the immunostimulatory response triggered by TS shRNA. Consequently, such enhanced accumulation of TS shRNA-lipoplex along with the cytotoxic effect of liposomal l-OHP led to a remarkable tumor growth suppression (compared to mono-therapy) following systemic administration. Our results, therefore, may have important implications for the provision of a safer and more applicable combination therapy of RNAi molecules and anti-cancer agents that can produce a more reliable anti-tumor effect.

Ganglioside inserted into PEGylated liposome attenuates anti-PEG immunity

Despite the clinical introduction of a vast number of polyethylene glycol (PEG)-conjugated therapeutics, conjugated PEG is also known for an unfortunate inclination toward immunogenicity. Immunogenicity of PEG, manifested by the robust production of anti-PEG IgM, is known to compromise the therapeutic efficacy and/or reduce the tolerance of PEGylated therapeutics. In the present study, we inserted ganglioside into the membrane of PEGylated liposome (PL) to prepare ganglioside-modified PEGylated liposomes (G-PL), and investigated its efficacy in attenuating the anti-PEG IgM response against PL. A single intravenous injection of G-PL significantly attenuated the anti-PEG IgM production, compared with that of naïve PL. In addition, pretreatment with G-PL substantially alleviated the anti-PEG IgM response elicited by a subsequent dose of PL, presumably via inducing B cell tolerance, and as a consequence, this modification abrogated/attenuated the incidence of the rapid clearance of subsequently administrated PL. These results indicate that incorporating gangliosides in PEGylated liposome membrane not only prevents the immunogenicity of PEG but also induces the tolerance of B cells to subsequent doses of the immunogenic PL. Consequently, liposomal membrane modification with ganglioside might represent a promising approach to attenuating the immunogenicity of PEGylated liposomes while preserving their therapeutic efficacy, particularly upon repeated administration.

Metronomic chemotherapy and nanocarrier platforms

The therapeutic concept of administering chemotherapeutic agents continuously at lower doses, relative to the maximum tolerated dose (MTD) without drug-free breaks over extended periods -known as "metronomic chemotherapy"- is a promising approach for anti-angiogenic cancer therapy. In comparison with MTD chemotherapy regimens, metronomic chemotherapy has demonstrated reduced toxicity. However, as a monotherapy, metronomic chemotherapy has failed to provide convincing results in clinical trials. Therapeutic approaches including combining the anti-angiogenic "metronomic" therapy with conventional radio-/chemo-therapy and/or targeted delivery of chemotherapeutic agents to tumor tissues via their encapsulation with nanocarrier-based platforms have proven to potentiate the overall therapeutic outcomes. In this review, therefore, we focused on the mutual contribution made by nanoscale drug delivery platforms to the therapeutic efficacy of metronomic-based chemotherapy. In addition, the influence that the dosing schedule has on the overall therapeutic efficacy of metronomic chemotherapy is discussed.

Systemically Administered RNAi Molecule Sensitizes Malignant Pleural Mesotheliomal Cells to Pemetrexed Therapy

Pemetrexed (PMX) is a key drug for the management of malignant pleural mesothelioma (MPM). However, its therapeutic efficacy is cruelly restricted in many clinical settings by the overexpression of thymidylate synthase (TS) gene. Recently, we emphasized the efficacy of locally administered shRNA designed against TS gene in enhancing the cytotoxic effect of PMX against orthotopically implanted MPM cells in tumor xenograft tumor model. Herein, we explored the efficiency of systemic, rather than local, delivery of TS RNAi molecule in sensitizing MPM cells to the cytotoxic effect of PMX. We here designed a PEG-coated TS shRNA-lipoplex (PEG-coated TS shRNA-lipoplex) for systemic injection. PEG modification efficiently delivered TS shRNA in the lipoplex to tumor tissue following intravenous administration as indicated by a significant suppression of TS expression level in tumor tissue. In addition, the combined treatment of PMX with systemic injection of PEG-coated TS shRNA-lipoplex exerted a potent antitumor activity in a s.c. xenograft tumor model, compared to a single treatment with either PMX or PEG-coated TS shRNA-lipoplex. Metastasis, or the spread, of mesothelioma substantially dedicates the effectiveness of treatment options. The systemic, in addition to local, delivery of tumor targeted anti-TS RNAi system we propose in this study might be an effective option to extend the clinical utility of PMX in treating malignant mesothelioma.

Improvement of intratumor microdistribution of PEGylated liposome via tumor priming by metronomic S-1 dosing

The efficient delivery of nanocarrier-based cancer therapeutics into tumor tissue is problematic. Structural abnormalities, tumor vasculature heterogeneity, and elevated intratumor pressure impose barriers against the preferential accumulation of nanocarrier-based cancer therapeutics within tumor tissues and, consequently, compromise their therapeutic efficacy. Recently, we have reported that metronomic S-1, orally available tegafur formulation, dosing synergistically augmented the therapeutic efficacy of oxaliplatin (l-OHP)-containing PEGylated liposome without increasing the toxicity in animal model. However, the exact mechanism behind such synergistic effect was not fully elucidated. In this study, therefore, we tried to shed the light on the contributions of metronomic S-1 dosing to the enhanced accumulation and/or spatial distribution of PEGylated liposome within tumor tissue. Tumor priming with metronomic S-1 treatment induced a potent apoptotic response against both angiogenic endothelial cells and tumor cells adjacent to tumor blood vessels, resulting in enhanced tumor blood flow via transient normalization of tumor vasculature, along with alleviation of intratumor pressure. Such a change in the tumor microenvironment imparted by S-1 treatment allows efficient delivery of PEGylated liposome to tumor tissue and permits their deep penetration/distribution into the tumor mass. Such a priming effect of S-1 dosing can be exploited as a promising strategy to enhance the therapeutic efficacy of nanocarrier-based cancer therapeutics suffering from inadequate/heterogeneous delivery to tumor tissues.

Downregulation of thymidylate synthase by RNAi molecules enhances the antitumor effect of pemetrexed in an orthotopic malignant mesothelioma xenograft mouse model

Malignant pleural mesothelioma (MPM) is an incurable cancer with an increasing incidence. Currently, pemetrexed (PMX)-based chemotherapy is the mainstay of chemotherapy for MPM, however, the outcome of PMX-based chemotherapy in patients with MPM is dismal. RNA interference (RNAi) technology has been considered as an effective tool to substantially enhance the therapeutic efficacy of chemotherapeutic agents in many preclinical and clinical settings. In this study, therefore, we investigated whether non-viral anti-thymidylate synthase RNAi embedded liposome (TS shRNA lipoplex) would effectively guide the downregulation of TS in human malignant mesothelioma MSTO-211H cells. Consequently, it enhanced the antitumor effect of PMX both in vitro and in vivo. TS shRNA effectively enhanced the in vitro cell growth inhibition upon treatment with PMX via downregulating TS expression in the MSTO-211H cell line. In in vivo orthotopic tumor model, the combined treatment of PMX and TS shRNA lipoplex efficiently combated the progression of orthotopic thoracic tumors and as a result prolonged mouse survival, compared to each single treatment. Our findings emphasize the pivotal relevance of RNAi as an effective tool for increasing the therapeutic efficacy of PMX, a cornerstone in the treatment regimens of MPM, and thereby, raising the possibility for the development of a novel therapeutic strategy, combination therapy of TS-shRNA and PMX, that can surpass many of the currently applied, but less effective, therapeutic regimens against lethal MPM.

Intra-tumor distribution of PEGylated liposome upon repeated injection: No possession by prior dose

Liposomes have proven to be a viable means for the delivery of chemotherapeutic agents to solid tumors. However, significant variability has been detected in their intra-tumor accumulation and distribution, resulting in compromised therapeutic outcomes. We recently examined the intra-tumor accumulation and distribution of weekly sequentially administered oxaliplatin (l-OHP)-containing PEGylated liposomes. In that study, the first and second doses of l-OHP-containing PEGylated liposomes were distributed diversely and broadly within tumor tissues, resulting in a potent anti-tumor efficacy. However, little is known about the mechanism underlying such a diverse and broad liposome distribution. Therefore, in the present study, we investigated the influence of dosage interval on the intra-tumor accumulation and distribution of "empty" PEGylated liposomes. Intra-tumor distribution of sequentially administered "empty" PEGylated liposomes was altered in a dosing interval-dependent manner. In addition, the intra-tumor distribution pattern was closely related to the chronological alteration of tumor blood flow as well as vascular permeability in the growing tumor tissue. These results suggest that the sequential administrations of PEGylated liposomes in well-spaced intervals might allow the distribution to different areas and enhance the total bulk accumulation within tumor tissue, resulting in better therapeutic efficacy of the encapsulated payload. This study may provide useful information for a better design of therapeutic regimens involving multiple administrations of nanocarrier drug delivery systems.

Advanced therapeutic approach for the treatment of malignant pleural mesothelioma via the intrapleural administration of liposomal pemetrexed

Malignant pleural mesothelioma (MPM) is an aggressive cancer that proliferates in the pleural cavity. Pemetrexed (PMX) in combination with cisplatin is currently the approved standard care for MPM, but a dismal response rate persists. Recently, we prepared various liposomal PMX formulations using different lipid compositions and evaluated their in vitro cytotoxicity against human mesothelioma cells (MSTO-211H). In the present study, we investigated the in vivo therapeutic effect of our liposomal PMX formulations using an orthotopic MPM tumor mouse model. PMX encapsulated within either cholesterol-containing (PMX/Chol CL) or cholesterol-free (PMX/Non-Chol CL) cationic liposome was intrapleurally injected into tumor-bearing mice. PMX encapsulated in cholesterol-free liposomes (PMX/Non-Chol CL) drastically inhibited the tumor growth in the pleural cavity, while free PMX and PMX encapsulated in cholesterol-containing liposomes (PMX/Chol CL) barely inhibited the tumor growth. The enhanced in vivo anti-tumor efficacy of PMX/Non-Chol CL was credited, on the one hand, for prolonging the retention of cationic liposomes in the pleural cavity via their electrostatic interaction with the negatively charged membranes of tumor cells, but on the other hand, it was charged with contributing to a higher drug release from the "fluid" liposomal membrane following intrapleural administration. This therapeutic strategy of direct intrapleural administration of liposomal PMX, along with the great advances in CL-guided therapeutics, might be a promising therapeutic approach to conquering the poor prognosis for MPM.

Sequential treatment of oxaliplatin-containing PEGylated liposome together with S-1 improves intratumor distribution of subsequent doses of oxaliplatin-containing PEGylated liposome

We recently reported that combination therapy with metronomic S-1 dosing and oxaliplatin (l-OHP)-containing PEGylated liposomes improved antitumor activity in a murine colorectal tumor model. However, little is known about the mechanism underlying such improved therapeutic efficacy. Here we investigated the impact of combined treatment on biodistribution, tumor accumulation and intratumor distribution of test PEGylated liposomes and on the structure of tumor vasculature in a solid tumor. The combined treatment clearly enhanced tumor accumulation and intratumor distribution of a subsequent test dose of PEGylated liposome as a result of on the one hand prolonging blood circulation of test liposome and on the other hand the alteration in tumor microenvironment. The l-OHP-containing PEGylated liposomes contributed predominantly to the enhanced tumor accumulation and altered tumor distribution of test liposome. On the other hand, metronomic S-1 dosing contributed to the altered tumor distribution but not the tumor accumulation of test liposome. The antitumor effect of the combined treatment, reflected by the proportion of apoptotic cells in the tumor, was approximately equally accounted for by each of the two treatments, leading to a roughly additive effect. In conclusion, 1-OHP-containing PEGylated liposome together with S-1 enhanced intratumor influx, leading to improved antitumor activity of subsequently injected 1-OHP-containing PEGylated liposomes and/or S-1. This strategy we propose, which is clinically applicable, may overcome the problems related to the use of EPR effect-based nanocarrier systems.