Current Drug Delivery - Volume 9, Issue 1, 2012

The ninth birthday of Current Drug Delivery is being celebrated by the publication of a hot topic issue entitled, “Functional Complementation, Molecular Targeted Strategies, and Chemo/ Immuno-Sensitization in Cancer Treatment: Hurdles and Solutions”. Our being guest edited by A.R. Jazirehi, UCLA School of Medicine. He has contributed with an interesting article describing novel approaches to modulating apoptosis resistance and provides a comprehensive discussion of chronic lymphocytic leukemia. Other articles deal with molecular targeted therapies for melanoma, strategies for targeting cancer stem cells, the clinical use of rituximab to treat HIV related lymphoma and multicentric Castleman's disease. We also learn about the use of specific monoclonal antibodies to target immunogenic tumor membrane proteins in patients with recurrent pancreatic and colon cancer. In the general section, the issue describes the use of microneedles as transdermal delivery systems in combination with other strategies, a dual controlled release method used in dental medications, the use of botulinum toxin in prostate disease, an interesting formulation of chitosan/poly-(glutamic acid) for intestinal delivery of lansoprazole and an interesting coating of 5-fluorouracil tablets to treat colorectal cancer. I am sure that the articles will generate great interest.

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Mounting effective anti-tumor immune responses by cytotoxic effectors is important for the clearance of tumors. However, accumulated evidence suggests that the cytotoxic function of immune effectors is largely suppressed in the tumor microenvironment by a number of distinct effectors and their secreted factors. The aims of this review are to provide a rationale and potential mechanism for immunosuppression in cancer, and to demonstrate the significance of such immunosuppression in cellular differentiation and tissue regeneration in pathological conditions, and progression of cancer. We have recently shown that increased NK cell function was seen when they were cultured with primary oral squamous carcinoma stem cells (OSCSCs) as compared to their more differentiated oral squamous carcinoma cells (OSCCs). In addition, human embryonic stem cells (hESCs), Mesenchymal Stem Cells (hMSCs), dental pulp stem cells (hDPSCs) and induced pluripotent stem cells (hiPSCs) were significantly more susceptible to NK cell mediated cytotoxicity than their differentiated counterparts or parental cells from which they were derived. We have also reported that inhibition of differentiation or reversion of cells to a less-differentiated phenotype by blocking NFκB or targeted knock down of COX2 augmented NK cell function significantly. Total population of monocytes and those depleted of CD16(+) subsets were able to substantially prevent NK cell mediated lysis of OSCSCs, MSCs and DPSCs. Taken together, our results suggest that stem cells are significant targets of the NK cell cytotoxicity. The concept of split anergy in NK cells and its contribution to tissue repair and regeneration and in tumor resistance and progression will be discussed in this review. Therefore, patients with cancer may benefit from repeated allogeneic NK cell transplantation at the site of the tumor for specific elimination of cancer stem cells.

Cutaneous melanoma is the most aggressive skin cancer. Beside surgery, it is treated with chemotherapy and immunotherapy. However, many patients relapse after adjuvant therapy. The recent identification of several key molecular pathways implicated in the pathogenesis of melanoma is spreading development of a number of new translational targeted therapies which could play an important role in overcoming or minimizing resistance to chemotherapeutic drugs and proapoptotic therapies. This review summarizes environmental factors and the most significant molecular events involved in melanoma pathogenesis, disclosing mechanisms responsible for drug resistance and pointing out the clinical view for emerging targeted therapies. Standard therapies and an update on the current clinical trials are also described.

Chronic lymphocytic leukemia (CLL) is an archetype of malignancy resulting from defects in apoptosis. CLL is an exclusive accumulative disorder marked by low proliferative activity and gradual accumulation of clonal B-lymphocytes blocked in the early (G0, G1) phases of the cell cycle. The heterogeneous clinical course indicates diverse in vivo biology of the leukemic cell and suggests that CLL represents diverse behavior. Understanding the molecular biology of the disease has provided insight into the mechanisms that promote tumorigenesis, specifically defective apoptotic signaling pathways. In this review we attempt to provide a comprehensive discussion of CLL including the origin of malignant lymphocytes, the apoptotic defects and the mechanisms leading to disease progression. We further discuss the therapeutic options, focusing mainly on targeted therapy using novel agents. Finally, we suggest future directions for treatment that utilize the understanding of the disease biology.

The use of immunotherapy in the treatment of non-Hodgkin lymphomas has improved response rates and survival in this population. With widespread rituximab use and longer-term follow-up of patients receiving rituximab, infectious complications are increasing. These complications are of great concern in the AIDS-related lymphoma population. We review the data on activity and infectious toxicity of rituximab to date and as it pertains to the treatment of AIDSrelated non-Hodgkin lymphoma and Multicentric Castleman's disease.

Tumor associated antigens from pooled allogeneic membrane proteins were isolated, partially purified and tested as a possible vaccine in patients with stage II and III colon cancer. The vaccine, when given in combination with an adjuvant following surgical resection, resulted in marked improvement in survival compared to control patients having only undergone surgical resection of their tumor. While it was possible to demonstrate that patients receiving vaccine turned on both humoral and cell mediated responses, it appears that survivors remaining free of disease at 5-7 yrs post op were able to mount a strong IgG1 response as the primary mechanism for tumor destruction. Antibodies from hybridomas made against the vaccines resulted in production of monoclonals with a high degree of ADCC. Those monoclonals targeting pancreatic cancer and in particular the MUC5ac mutated antigen representing tumor immunogen were studied in detail. Animal models indicated rapid tumor destruction when nude mice, injected with human pancreatic cancer were then immunized with NPC-1 monoclonal antibody targeting mutated MUC5ac. FDA studies including tissue cross reactivity, biodistribution, and cytokine release assays indicated safety and efficacy of the monoclonals we have developed. Submission of the IND allowed for initiation of the Phase I trial using mAb NPC-1 targeting pancreatic cancer when that antigen was found to be expressed.

Transdermal drug delivery has exhaustively been studied over the past decades due to its multiple advantages over other administration routes; however, drugs that can be administered by this via are few owe to the stratum corneum permeability properties. Recently, several strategies to bypass the upper-layer skin barrier have been developed. One of the latest advances in this area has been the use of micro-scale needles, which painlessly pierce skin, increasing the passage of drugs with unfavourable skin permeability (i.e., low potent, hydrophilic, high molecular drugs) by several orders of magnitude, by bypassing the stratum corneum. Microneedles have shown to be safe and easy-to-use for drug administration, a nouvelle alternative to hypodermic needle injections, and an array in which drugs can be included to attain a controlled release as to achieve a higher drug delivery. Several works have demonstrated that such devices dramatically increase transdermal delivery of large molecules, thus nowadays microneedles have been regarded as a potential technology approach to be employed alone or with other enhancing methods such as electroporation and iontophoresis, as well as with different drug carriers (e.g., lipid vesicles, micro- and nanoparticles). Hence, this review is mainly focused on presenting the results obtained when combining microneedles with a variety of strategies to ease drug diffusion through skin, including physical enhancers and drug carrier systems.

In situ gelling syringeable periodontal sol capable of dual controlled delivery of metronidazole benzoate and serratiopeptidase was designed based on 23 factorial design with drug, poloxamer 407 and aerosil as independent variables and sol gel transition characteristics, %CDR48h and palatability as responses. The sols had agreeable taste, were mucoadhesive, syringeable and inverted into gels at periodontal cavity temperature. F8 with optimal drug release was identified as the best formulation. The dispersion characteristics of poloxamer significantly affected the pharmacotechnical properties of the in situ gelling systems. Extra design checkpoint generated using Design Expert software 8.02 (Stat-Ease, USA) validated the experimental design. Thus a thermoreversible, in situ gelling and syringeable periodontal sol with acceptable taste characteristics that offered controlled release of metronidazole benzoate and serratiopeptidase was developed for application into the periodontal pocket. The developed optimized sol was satisfactory in terms of taste, syringeability, palatability and incorporation of serratiopeptidase as anti-inflammatory agent, has the potential of developing a therapeutically efficacious system for treatment of periodontal inflammatory anaerobic infections.

Botulinum toxin is one of the most toxic natural substances; it acts by blocking the neuromuscular transmission by inhibiting Acetylcholine (Ach) releasing from the motor nerve into the neuromuscular junction. Although the toxin inhibits ACh release, other transmitters can also be inhibited. Botulinum toxin, specifically toxin type A (BONT-A) has been used since the 1970s to treat many different disorders, such as general spasticity resulting from stroke, multiple sclerosis or cerebral palsy, strabismus, hyperhidrosis or excessive sweating, pain, and it is effective in combating migraine and tension headaches. Since prostate gland is under the influence of autonomic innervation and associated neurotransmitters, the effects of BONT-A on the prostate have gained attention in the urological community and it has been studied in different species, including rats, dogs and humans. The aim of this paper is to review the mechanism of action of botulinum toxin and to discuss in particular the results of BONT-A treatment for benign prostatic hyperplasia (BPH), providing perspectives on potential therapy according to actual knowledge.

Lansoprazole sodium is a proton pump inhibitor used in treating gastroesophageal reflux disease (GERD). It is highly acid-labile and presents many formulation challenges. Therefore, this drug needs to be protected from the harsh environment in the stomach. In order to achieve this, a pH-sensitive microparticle system composed of chitosan and γ- poly-(glutamic acid) was prepared and loaded with Lansoprazole. The prepared microparticles were not stable in gastric pH. To overcome this problem microparticles were freez-dried and filled in an enteric-coated capsule. Upon oral administration, the enteric-coated capsule remained intact in the acidic environment of the stomach, but dissolved rapidly in the distal segment of the GIT. Consequently, all the microparticles loaded in the capsule were brought into the intestine, thus enhancing the intestinal absorption of drug. Drug encapsulation efficiency of formulation F3 was found to be 82.82 % and in vitro release of prepared formulation F3 was found to be 94% after 8 h of dissolution in 7.4 pH phosphate buffer. FTIR and DSC studies showed no interaction between the drug and polymer. The formulation showed good swelling property. SEM photographs showed that microparticles are spherical and lies in size range of 300-400 μm. From the above, it can be concluded that the prepared chitosan/ γ-poly-(glutamic acid) microparticles can be used as carriers for the intestinal delivery of acid liable drugs such as lansoprazole.

The colon and rectum are the parts of digestive system of human beings. Cancer affecting either of these organs may be called colorectal cancers. Conventional cancer chemotherapy is not very effective for treatment of colorectal cancer, as the drug molecule does not reach the target site at therapeutic concentration, on the other side they produces sever systemic toxic effect. Aim of this study was to develop a novel colon targeted Assam Bora rice starch compression coated tablet for site specific delivery of 5-FU to the colon without the drug being released in stomach or small intestine. Core tablet of 5-FU was prepared using microcrystalline cellulose (MCC) and spray dried lactose by direct compression method. The in vitro drug release study in different physiological environment confirmed insignificant release of 5-FU in physiological condition of stomach and small intestine further fast and major drug release in caecal content. In vivo drug absorption of optimized formulation was performed in order to establish its targeting potential in colon. It is concluded from the present study that Assam Bora rice starch can be used as a drug carrier for an effective colon targeted delivery system for drugs effective against the large intestine resident disease condition.