Reduced folate carrier independent internalization of PEGylated pemetrexed: a potential nanomedicinal approach for breast cancer therapy.

Pemetrexed has been widely used as an effective chemotherapeutic agent for the treatment of a variety of cancers including breast cancer. It is a multitargeted antifolate that gets transported to cells primarily by reduced folate carrier (RFC) and exerts its action by disrupting folate-dependent metabolic processes essential for cell replication. The loss of RFC leads to impaired transport of pemetrexed, which in turn decreases its intracellular concentration and reduces its cytotoxic effect on cancer cells. Furthermore, the multidrug resistance (MDR) related proteins (MRPs) contribute to pemetrexed efflux from the cancer cells. These observations prompted us to develop PEGylated pemetrexed that follows an efficient cellular internalization route independent of RFC and simultaneously bypasses the MRP efflux mechanism for acting as an efficient chemotherapeutic agent. Thus, the present study focuses on PEGylation of pemetrexed for its superior therapeutic efficiency by evaluating its cellular uptake and retention by flow cytometry, confocal microscopy, and reversed-phase high-performance liquid chromatography (RP-HPLC) in breast cancer cell lines having RFC expression and lacking RFC expression, that is, MCF7 and MDA MB231, respectively. In addition, the treatment of PEGylated pemetrexed lead to enhanced cytotoxicity due to S-phase arrest and apoptosis in the above mentioned cell lines. Interestingly, the longer circulation time of PEGylated pemetrexed in animal model concomitant with the RFC independent uptake and enhanced cytotoxicity suggests it to be a potential candidate for cancer therapy in a clinical setting.

Enhanced antiproliferative activity of Herceptin (HER2)-conjugated gemcitabine-loaded chitosan nanoparticle in pancreatic cancer therapy.

Currently, effective drug delivery in pancreatic cancer treatment is a major challenge. Nanomedicine plays an essential role by delivering anticancer drugs in a targeted manner to the malignant tumor cells, leading to increased efficacy by reducing the toxicity of anticancer drugs to normal, sensitive sites. This study investigated the preparation and characterization of a targeted system represented by Herceptin-conjugated gemcitabine-loaded chitosan nanoparticles (HER2-Gem-CS-NPs) for pancreatic cancer therapy. The targeted NPs displayed superior antiproliferative activity along with an enhanced S-phase arrest, leading to apoptosis in comparison with unconjugated gemcitabine-loaded nanoparticles and free gemcitabine due to higher cellular binding with eventual uptake and prolonged intracellular retention. Thus, HER2-Gem-CS-NPs are able to provide an efficient and targeted delivery of gemcitabine for pancreatic cancer treatment. FROM THE CLINICAL EDITOR: This study investigated the preparation and characterization of a targeted drug delivery system consisting of Herceptin-conjugated gemcitabine-loaded chitosan nanoparticles for pancreatic cancer therapy.

Synergistic activity of combination therapy with PEGylated pemetrexed and gemcitabine for an effective cancer treatment.

Combination therapy in cancer is now opted as a potential therapeutic strategy for cancer treatment. However, effective delivery of drugs in combination at the tumor site is marred by low bioavailability and systemic toxicity of individual drugs. Polymer therapeutics is indeed an upcoming approach for the combinational drug delivery in favor of better cancer management. Hence, the objective of our investigation was to develop a dual drug PEGylated system that carries two chemotherapeutic drugs simultaneously for effective treatment of cancer. In this regard, we have synthesized Pem-PEG-Gem, wherein pemetrexed (Pem) and gemcitabine (Gem) are conjugated to a heterobifunctional polyethylene glycol (PEG) polymer for the effective treatment of Non-Small Cell Lung Cancer (NSCLC). Our results demonstrate enhanced bioavailability of the individual drugs in Pem-PEG-Gem in comparison with the drugs in their native form. The developed Pem-PEG-Gem showed enhanced cell death with respect to their native counterparts when treated singly or in combination against NSCLC cells. This might be attributed to better cellular internalization through the process of macropinocytosis and synergistic cytotoxic action of Pem-PEG-Gem in NSCLC cells. Hence, we propose the above dual drug based polymer therapeutic approach suitable for better clinical application in the treatment of NSCLC.

Multimodal Treatment Eliminates Cancer Stem Cells and Leads to Long-Term Survival in Primary Human Pancreatic Cancer Tissue Xenografts.

PURPOSE: In spite of intense research efforts, pancreatic ductal adenocarcinoma remains one of the most deadly malignancies in the world. We and others have previously identified a subpopulation of pancreatic cancer stem cells within the tumor as a critical therapeutic target and additionally shown that the tumor stroma represents not only a restrictive barrier for successful drug delivery, but also serves as a paracrine niche for cancer stem cells. Therefore, we embarked on a large-scale investigation on the effects of combining chemotherapy, hedgehog pathway inhibition, and mTOR inhibition in a preclinical mouse model of pancreatic cancer. EXPERIMENTAL DESIGN: Prospective and randomized testing in a set of almost 200 subcutaneous and orthotopic implanted whole-tissue primary human tumor xenografts. RESULTS: The combined targeting of highly chemoresistant cancer stem cells as well as their more differentiated progenies, together with abrogation of the tumor microenvironment by targeting the stroma and enhancing tissue penetration of the chemotherapeutic agent translated into significantly prolonged survival in preclinical models of human pancreatic cancer. Most pronounced therapeutic effects were observed in gemcitabine-resistant patient-derived tumors. Intriguingly, the proposed triple therapy approach could be further enhanced by using a PEGylated formulation of gemcitabine, which significantly increased its bioavailability and tissue penetration, resulting in a further improved overall outcome. CONCLUSIONS: This multimodal therapeutic strategy should be further explored in the clinical setting as its success may eventually improve the poor prognosis of patients with pancreatic ductal adenocarcinoma.

Long circulation and cytotoxicity of PEGylated gemcitabine and its potential for the treatment of pancreatic cancer.

Gemcitabine [2', 2'-difluoro-2'-deoxycytidine (dFdC)] is a low molecular weight, deoxycytidine analog inhibiting cellular DNA synthesis. Currently, it is the frontline drug approved by Food and Drug Administration (FDA) for the treatment of pancreatic cancer. However, efforts to use gemcitabine as an anti-cancer agent have been limited by its short circulation time and rapid metabolism that reflects in low tumor uptake and intracellular action. Polymer-drug conjugates, in this regard have spawned an approach to improve the cytotoxicity efficiency and bioavailability of gemcitabine by chemical modification. The present study describes the synthesis of a water soluble formulation of PEGylated gemcitabine characterized by FT IR, (1)H NMR and RP-HPLC chromatography. The PEGylated gemcitabine has a prolonged circulation time in plasma as studied in an animal model. This eventually caused a marked improvement in the cytotoxicity and apoptosis-inducing activity in pancreatic cancer cell lines (MIA PaCa 2 and PANC 1). Hence, these findings demonstrate the PEGylated gemcitabine is a desirable approach for therapy by intravenous administration. Successful clinical application of this approach can significantly contribute to the treatment of pancreatic cancer.

Optimization of physicochemical parameters influencing the fabrication of protein-loaded chitosan nanoparticles.

AIM: In the development of controlled-release protein therapeutics, the high encapsulation of proteins into biodegradable nanoparticles with uniform size in an anhydrous process along with an excellent redispersion is of practical interest. The objective of this work was to study the physicochemical and in vitro release properties of chitosan nanoparticles with different molecular weights (low, medium and high) using bovine serum albumin (BSA) as a model protein for developing nanoparticle formulations that were stable and reproducible after lyophilization. MATERIALS & METHODS: The BSA-loaded chitosan nanoparticles were prepared by an ionic gelation method using pentasodium tripolyphosphate as the polyanions. The physicochemical properties and in vitro release kinetics of the nanoparticles were evaluated along with Fourier transform infrared spectroscopy studies. Furthermore, the nanoparticles were freeze-dried for long-term stability in the formulation. To optimize the size of the freeze-dried nanoparticles after redispersion, various types of lyoprotectants (natural and synthetic) were tested in varying concentration in the process of lyophilization. RESULTS: The dynamic light scattering measurements revealed the increase in size of chitosan nanoparticles with the increase in molecular weight of chitosan with no significant change, irrespective of the concentration of BSA entrapped. In addition, the entrapment efficiency of the nanoparticles increased with the increasing molecular weight of chitosan and BSA concentration. By contrast, the redispersity of the freeze-dried samples resulted in further increase of the mean diameter of the nanoparticles. CONCLUSION: Among the various types of lyoprotectants (natural and synthetic) examined, sucrose proved to be very effective in reducing the size of freeze-dried nanoparticles on redispersion without significant change in surface charge of nanoparticles. Finally, the in vitro release kinetics of BSA from nanoparticles of different molecular weights of chitosan, with and without sucrose, was evaluated and found to depend upon the molecular weight of chitosan.