Development of regional chemotherapies: feasibility, safety and efficacy in clinical use and preclinical studies

Current progress of nanomedicine for prostate cancer diagnosis and treatment

Prostate cancer (PCa) is the most common new cancer case and the second most fatal malignancy in men. Surgery, endocrine therapy, radiotherapy and chemotherapy are the main clinical treatment options for PCa. However, most prostate cancers can develop into castration-resistant prostate cancer (CRPC), and due to the invasiveness of prostate cancer cells, they become resistant to different treatments and activate tumor-promoting signaling pathways, thereby inducing chemoresistance, radioresistance, ADT resistance, and immune resistance. Nanotechnology, which can combine treatment with diagnostic imaging tools, is emerging as a promising treatment modality in prostate cancer therapy. Nanoparticles can not only promote their accumulation at the pathological site through passive targeting techniques for enhanced permeability and retention (EPR), but also provide additional advantages for active targeting using different ligands. This property results in a reduced drug dose to achieve the desired effect, a longer duration of action within the tumor and fewer side effects on healthy tissues. In addition, nanotechnology can create good synergy with radiotherapy, chemotherapy, thermotherapy, photodynamic therapy and gene therapy to enhance their therapeutic effects with greater scope, and reduce the resistance of prostate cancer. In this article, we intend to review and discuss the latest technologies regarding the use of nanomaterials as therapeutic and diagnostic tools for prostate cancer.

Synchronizing the release rates of topotecan and paclitaxel from a self-eroding crosslinked chitosan - PLGA platform

This study is a continuation of a previous study in which two model drugs, sodium salicylate (highly water-soluble) and indomethacin (low water-soluble) were loaded into an erodible hydrogel, made of ionically crosslinked chitosan (x-Ct). The erosion rate of the x-Ct matrix was controlled by its immersion in calcium chloride solutions (de-crosslinker) of different concentrations, leading to synchronization of the release rates of the two drugs over 2 h. In the present study, a modified platform was developed in order to (a) synchronize the release rates of the two cytotoxic drugs, topotecan (TT, highly water soluble) and paclitaxel (PTX, poorly water soluble); (b) prolong the erosion duration and the derived concomitant release of the two drugs to several days. TT was loaded into a PLGA sphere, which was co-loaded with calcium chloride (CaCl₂). The sphere was then placed in an aqueous solution of chitosan (Ct) in which PTX was dispersed. A PLGA core-containing hydrogel was then produced by ionically crosslinking the Ct. The formulation screening section of the study includes a statistically designed Fractional Factorial experiment. It was comprised of the following five experimental factors: (a) the type of Ct and (b) its relative amount in the formulation, (c) the type of ionic crosslinker (citric acid or oxalic acid), (d) the concentration of the ionic crosslinker and (e) the co-loaded amounts of CaCl₂ (the constitutional de-crosslinking agent). The difference factor, f1, and the similarity factor, f2, of the TT and PTX release profiles into water, were used as the experimental responses. The computerized prediction models were employed to assess the collective effects of the pre-determined experimental factors on the difference factor, f1, and the similarity factor, f2 (the response factors), by employing a fractional factorial design and multifactorial analysis, without the need to account for the exact mechanisms of the release processes involved. The final composite platform was capable of releasing TT and PTX, at similar (concomitant) rates, over a period of 7 days, a finding which suggests that the novel polymeric platform may serve as a multi-drug implant. An attractive medical application for such a device would be post-operative local treatment that could benefit from localized combination chemotherapy after the removal of malignant tissues, in the surgical treatment of breast cancer, ovarian cancer, glioma and peritoneal carcinomatosis.

Novel polymeric derivatives of betulin with anticancer activity

In order to provide novel polymeric biomaterials for chemotherapeutic purposes, in this paper we described the synthesis and the characterization of the physicochemical properties of a betulin-based polyanhydride exhibiting anti-cancer effects.

Synchronizing the release rates of salicylate and indomethacin from degradable chitosan hydrogel and its optimization by definitive screening design

Three types of ionically crosslinked (with citric acid) chitosan discs were loaded with the highly water- soluble drug, sodium salicylate (SS) and the poorly water-soluble drug, indomethacin (Ind). In separate experiments the hydrated discs were immersed in a de-crosslinking solution comprising of different concentrations of calcium chloride, which induced a controlled erosion of the discs, a process which was optimized to synchronize the release rates of the two drugs over a predetermined period of time. The optimization was accomplished by manipulating six factors: chitosan MW, its amount in the formulation, the concentration of the crosslinker agent, the concentration of the de-crosslinking agent in the dissolution medium, its pH and its temperature. A computerized multifactorial definitive screening design analysis assisted in minimizing the number of experiments. The quotient of the SS to Ind release rates, the difference factor f1, the similarity factor f2 and the combination of f1 and f2 were determined as the experimental responses. The computerized prediction profilers that were used to simulate the contribution of the experimental factors and their effect on the experimental responses led to a successful erodible formulation with a concomitant release of the two drugs over 150 min.

Current prospects and challenges of nanomedicine delivery in prostate cancer therapy

Management of prostate cancer is currently being pursued by systemic delivery of anticancer drugs, but it has drawbacks like nonspecific distribution, decreased bioavailability, coupled with adverse side effects. These problems have been resolved using nanomedicine-based anticancer drug delivery to improve the therapeutic index with higher drug dose and reduced nonspecific distribution. Targeting prostate tumor by delivering nanomedicine through locoregional route is more effective, than the systemic delivery, which can decrease systemic exposure of the therapeutics significantly. Therefore, in this article, we have reviewed the current prospects and challenges of prostate cancer therapy using nanomedicine, by providing a comprehensive description of advantages and limitations of the systemic route and locoregional route. Eventually, we have emphasized on the need for localized prostate cancer therapy developments using nanomedicines.

Systemic chemotherapy is modulated by platelet-activating factor-receptor agonists

Chemotherapy is used to treat numerous cancers including melanoma. However, its effectiveness in clinical settings is often hampered by various mechanisms. Previous studies have demonstrated that prooxidative stressor-mediated generation of oxidized lipids with platelet-activating factor-receptor (PAF-R) agonistic activity induces systemic immunosuppression that augments the growth of experimental melanoma tumors. We have recently shown that treatment of murine B16F10 melanoma cells in vitro or tumors implanted into syngeneic mice and treated intratumorally with various chemotherapeutic agents generated PAF-R agonists in a process blocked by antioxidants. Notably, these intratumoral chemotherapy-generated PAF-R agonists augmented the growth of secondary (untreated) tumors in a PAF-R dependent manner. As both localized and systemic chemotherapies are used based on tumor localization/stage and metastases, the current studies were sought to determine effects of PAF-R agonists on systemic chemotherapy against experimental melanoma. Here, we show that systemic chemotherapy with etoposide (ETOP) attenuates the growth of melanoma tumors when given subsequent to the tumor cell implantation. Importantly, this ETOP-mediated suppression of melanoma tumor growth was blocked by exogenous administration of a PAF-R agonist, CPAF. These findings indicate that PAF-R agonists not only negatively affect the ability of localized chemotherapy but also compromise the efficacy of systemic chemotherapy against murine melanoma.