Priyanka Bhatt

Protein– and Peptide–Drug Conjugates: An Emerging Drug Delivery Technology

Protein- and peptide-drug conjugates hold a promising stance in the delivery of therapeutic agents by providing distinct advantage of improving therapeutic potential of drugs. Recent advancements in the proteomics and recombinant DNA technology, by enabling identification of distinct structural features of proteins and making it feasible to introduce specific functionalities in protein/peptide structure, has made it possible to synthesize high quality protein- and peptide-drug conjugates though a wide variety of coupling techniques. Additionally, use of specialized linkers makes them unique in their in vivo therapeutic application by providing target tissue-specific release of drug. Several protein- and peptide-drug conjugates are currently under clinical trials warranting their huge market potential in near future. Increased understanding in this field will surely enable us to produce high quality protein- and peptide-drug conjugates which will serve therapeutic needs demanded from drug delivery systems in clinical settings.

Protein– and Peptide–Drug Conjugates

Protein- and peptide-drug conjugates hold a promising stance in the delivery of therapeutic agents by providing distinct advantage of improving therapeutic potential of drugs. Recent advancements in the proteomics and recombinant DNA technology, by enabling identification of distinct structural features of proteins and making it feasible to introduce specific functionalities in protein/peptide structure, has made it possible to synthesize high quality protein- and peptide-drug conjugates though a wide variety of coupling techniques. Additionally, use of specialized linkers makes them unique in their in vivo therapeutic application by providing target tissue-specific release of drug. Several protein- and peptide-drug conjugates are currently under clinical trials warranting their huge market potential in near future. Increased understanding in this field will surely enable us to produce high quality protein- and peptide-drug conjugates which will serve therapeutic needs demanded from drug delivery systems in clinical settings.

Receptor-targeted drug delivery: current perspective and challenges

Receptor-targeted drug delivery has been extensively explored for active targeting. However, the scarce clinical applications of such delivery systems highlight the implicit hurdles in development of such systems. These hurdles begin with lack of knowledge of differential expression of receptors, their accessibility and identification of newer receptors. Similarly, ligand-specific challenges range from proper choice of ligand and conjugation chemistry, to release of drug/delivery system from ligand. Finally, nanocarrier systems, which offer improved loading, biocompatibility and reduced premature degradation, also face multiple challenges. This review focuses on understanding these challenges, and means to overcome such challenges to develop efficient, targeted drug-delivery systems.

Liposomes encapsulating native and cyclodextrin enclosed paclitaxel: Enhanced loading efficiency and its pharmacokinetic evaluation

Combination strategy involving cyclodextrin (CD) complexation and liposomal system was investigated for Paclitaxel (PTX) to improve loading. Complexation was done using 2,6-di-O-methylbetacyclodextrin (DMβCD). Sterically stabilized double loaded PEGylated liposomes (DLPLs) containing PTX and PTX-DMβCD complex were prepared by thin film hydration. Physicochemical characterization of complex and prepared DLPLs was carried out. Cytotoxic potential, hemolytic potential and pharmacokinetics of DLPLs were tested in comparison to Taxol®. Aqueous solubility of PTX increased by almost 3 × 104 folds due to complexation with DMβCD as compared to pure drug solubility. Liposomal system was found to have 162.8 ± 4.1 nm size, zeta potential of -5.6 ± 0.14 mV and 2-fold increase in drug loading to 5.8 mol % for PTX due to double loading. DLPLs had low hemolytic potential and higher cytotoxicity on SKOV3 cells with improvement in IC50 value by 4.2 folds as compared to Taxol® at 48 h. The anti-angiogenic potential of DLPLs was confirmed by 1.33 folds lesser wound recovery in SKOV3 cells compared to Taxol®. In-vivo pharmacokinetic evaluation of DLPLs in rats substantiates improvement in circulation time, higher plasma concentration and decreased clearance rate compared to Taxol®. An efficacious system with improved loading and pharmacokinetics was formulated as potential alternative for currently marketed PTX formulation.

Low molecular weight chitosan–protamine conjugate for siRNA delivery with enhanced stability and transfection efficiency

Chitosan is among the few polymers with high biocompatibility and low toxicity. In the area of siRNA delivery, chitosan has been noted for its high buffer capacity in endosomal pH range. However, its applications are limited due to unfavorable physicochemical properties such as poor solubility, colloidal instability, unionized nature and weak binding with nucleic acids at physiologic pH which leads to premature release of nucleic acids, poor cell uptake and transfection. In order to overcome these limitations of chitosan, low molecular weight chitosan (LMWC) were prepared to improve its solubility and colloidal stability at physiologic pH. The obtained LMWC was conjugated with protamine to impart cationic charge and induce preferential binding with siRNA at physiologic pH. The polyplex were subjected to ionic cross-linking resulting in particle size of 143.7 nm and zeta potential of +12.8 mV. The polyplexes displayed enhanced resistance to displacement in heparin competition assay and to degradation in serum stability studies. Covalent conjugation also provided combined advantage of higher uptake due to cationic charge of protamine and endosomal escape capability of LMWC. The conjugate showed low cytotoxicity, high transfection efficiency and gene expression in vitro and were found safe in vivo.

Role of antibodies in diagnosis and treatment of ovarian cancer: Basic approach and clinical status

Ovarian cancer is the second most leading gynecological cancer after endometrial cancer in women. Chemotherapy and cyto-reductive surgery are currently the mainstays for treatment of ovarian cancer in early stages. However, the overall 5years of survival rate in advanced stage is just 20-30%. The main reasons behind therapeutic failures and a low survival rate are challenges in early diagnosis, frequent recurrence, chemo-resistance development and lack of targeting. Antibodies have evolved as a rationale therapeutic approach to overcome these hurdles and to engender significant clinical applications. Detection of cancer associated antibodies and radiolabeled antibody conjugates are forming the basis for early diagnosis of ovarian cancer. Besides this, antibodies when given alone act as an anti-angiogenic agent or utilize the protective role of immune system against ovarian cancer. This high specificity and selectivity of action is also accompanied by development of tumor antigen-specific memory T cells, which can prevent cancer recurrence. In addition, when given in combination with chemotherapy, antibodies have turned out to sensitize chemo-resistant tumors. Antibodies are also playing cardinal role in design of highly potent class of targeted therapies, such as antibody-drug conjugates and clinically viable tumor targeted drug nanocarriers. This article aims to explore the fundamentals in development of antibody based therapeutics and multitude ways of clinical applications in diagnosis and treatment of ovarian cancer. Focus is given on the recent advances made in preclinical and clinical settings with an overview to unmet challenges so as to develop better immunotherapeutics in future.

Microbeads mediated oral plasmid DNA delivery using polymethacrylate vectors: an effectual groundwork for colorectal cancer

Abstract This study was aimed to develop and evaluate p53 polyplex-loaded enteric-coated calcium pectinate microbeads for oral gene delivery as an effective novel alternative for colorectal cancer therapy. Mutation in p53 is the key event in colorectal cancer (CRC) and an important target for the treatment of CRC through gene therapy. Polymethacrylates-based non-viral vectors were evaluated for their ability to complex, protect and transfect p53 (wt) into colon cancer cell line. Polyplexes were formulated by complexation of cationic polymer with anionic pDNA at different N/P ratios. p53 polyplex-loaded calcium pectinate (CP) microbeads were prepared by ionotropic gelation of pectin with calcium chloride and coated with Eudragit® S100. In vitro release studies showed that enteric-coated CP microbeads protected the release of p53 polyplex in upper GIT with less than 10% release. In-vitro cell line studies and in vivo studies in rat showed that polymethacrylate carrier could transfect the pDNA effectively. Results of in vivo gene expression study further confirmed the ability of enteric-coated calcium pectinate microbeads to deliver pDNA specifically to rat colon. Conclusively, enteric-coated calcium pectinate microbeads released p53 polyplex specifically in colon and could serve as an effective alternative for CRC therapy.

Targeted delivery of monoclonal antibody conjugated docetaxel loaded PLGA nanoparticles into EGFR Overexpressed lung tumor cells

Abstract The aim of this study was to develop anti-EGFR antibody conjugated poly(lactide-co-glycolide) nanoparticles (NPs) to target epidermal growth factor receptor, highly expressed on non-small cell lung cancer cells to improve cytotoxicity and site specificity. Cetuximab was conjugated to docetaxel (DTX) loaded PLGA NPs by known EDC/NHS chemistry and characterised for size, zeta potential, conjugation efficiency and the results were 128.4 ± 3.6 nm, –31.0 ± 0.8 mV, and 39.77 ± 3.4%, respectively. In vitro release study demonstrated sustained release of drug from NPs with 25% release at pH 5.5 after 48 h. In vitro cytotoxicity studies demonstrated higher anti-proliferative activity of NPs than unconjugated NPs. Cell cycle analysis and apoptosis study were performed to evaluate extent of cell arrest at different phases and apoptotic potential for the formulations, respectively. In vivo efficacy study showed significant reduction in tumour growth and so antibody conjugated NPs present a promising active targeting carrier for tumour selective therapeutic treatment.

Challenges in Dermal Delivery of Therapeutic Antimicrobial Protein and Peptides

BACKGROUND Protein and peptides in biological system form an important part of innate immune system and are being explored for potential use in various diseases as therapeutics. Importance of proteins and peptides as a new class of antimicrobial agents has boosted research in the field of biotechnology as potential alternative to antibiotic agents. OBJECTIVE Protein and peptides antimicrobial as a therapeutic class are structurally diverse and exhibit potent activity against microbes by various mechanisms. However, they present formidable challenge in formulation due to requirement of specific spatial configuration for their activity and stability. Thus, encapsulation of these therapeutics in various nano-systems may sustain activity along with improvement in stability. METHOD The article highlights the need for antimicrobial peptides in dermal infections along with discussion of mechanism of their action. It highlights challenges faced for dermal delivery and research carried out for their successful delivery using nano-systems. RESULTS It is widely realized that these novel classes of therapeutic agents have tremendous market potential to emerge as an alternative to conventional antibiotic agents for combating issue of multidrug resistant microbial species. Research in their delivery aspects by use of current advances made in delivery systems through use of nanoconstructs offers much needed area for exploration and achieving success. CONCLUSION As there is an urgent need for coming up with new therapeutic agents for encompassing the increased burden of microbial diseases in human population as well as their delivery challenges, research in field will give the much-needed strategic advantage against pathogenic organisms.

Antimicrobial peptide delivery: an emerging therapeutic for the treatment of burn and wounds

The management of wounds and burns is becoming difficult using conventional therapeutics available due to resistance development by microbes. Therefore, there is an utmost need to develop therapeutic alternatives to these agents. Antimicrobial peptides have emerged as a novel class of agents for the effective management of wounds and burns due to their potent nature along with minimal chances of resistance development against them. This article focuses on highlighting the importance of these antimicrobial peptides among the various therapeutic alternatives for burns and wounds. Further, effective delivery strategies for these agents that are being employed and investigated are reported along with an overview of the importance of these agents in the coming years.