Pharmacokinetics and toxicity considerations for antibody-drug conjugates: an overview

Antibody-drug conjugates (ADCs) is one of the fastest-growing drug-delivery systems. It involves a monoclonal antibody conjugated with payload via a ligand that directly targets the expressive protein of diseased cell. Hence, it reduces systemic exposure and provides site-specific delivery along with reduced toxicity. Because of this advantage, researchers have gained interest in this novel system. ADCs have displayed great promise in drug delivery and biomedical applications. However, a lack of understanding exists on their mechanisms of biodistribution, metabolism and side effects. To gain a better understanding of the therapeutics, careful consideration of the pharmacokinetics and toxicity needs to be undertaken. In this review, different pharmacokinetics parameters including distribution, bioanalysis and heterogeneity are discussed for developing novel therapeutics.

Recent advances in nanoparticles mediated photothermal therapy induced tumor regression

Photothermal therapy (PTT) is a minimally invasive procedure for treating cancer. The two significant prerequisites of PTT are the photothermal therapeutic agent (PTA) and near-infrared radiation (NIR). The PTA absorbs NIR, causing hyperthermia in the malignant cells. This increased temperature at the tumor microenvironment finally results in tumor cell damage. Nanoparticles play a crucial role in PTT, aiding in the passive and active targeting of the PTA to the tumor microenvironment. Through enhanced permeation and retention effect and surface-engineering, specific targeting could be achieved. This novel delivery tool provides the advantages of changing the shape, size, and surface attributes of the carriers containing PTAs, which might facilitate tumor regression significantly. Further, inclusion of surface engineering of nanoparticles is facilitated through ligating ligands specific to overexpressed receptors on the cancer cell surface. Thus, transforming nanoparticles grants the ability to combine different treatment strategies with PTT to enhance cancer treatment. This review emphasizes properties of PTAs, conjugated biomolecules of PTAs, and the combinatorial techniques for a better therapeutic effect of PTT using the nanoparticle platform.

Emerging innovations in nano-enabled therapy against age-related macular degeneration: A paradigm shift

Age-related macular degeneration (AMD), a degenerative eye disease, is the major cause of irreversible loss of vision among individuals aged 50 and older. Both genetic and environmental factors are responsible for the progressive damage to central vision. It is a multifactorial retinal disease with features such as drusen, hypopigmentation and/or hyperpigmentation of the retinal pigment epithelium, and even choroidal neovascularization in certain patients. AMD is of two major forms: exudative (wet) and atrophic (dry) with changes affecting the macula leading to impaired vision. Although the retina remains an accessible portion for delivering drugs, there are no current options to cure or treat AMD. The existing expensive therapeutics are unable to treat the underlying pathology but display several side effects. However, recent innovations in nanotherapeutics provide an optimal alternative of drug delivery to treat the neovascular condition. These new-age technologies in the nanometer scale would enhance bioactivity and improve the bioavailability of drugs at the site of action to treat AMD. The nanomedicine also provides sustained release of the drug with prolonged retention after penetrating across the ocular tissues. In this review, the insights into the cellular and molecular mechanisms associated with the pathophysiology of AMD are provided. It also serves to review the current progress in nanoparticle-based drug delivery systems that offer feasible treatments in AMD.

Evolving new-age strategies to transport therapeutics across the blood-brain-barrier

A basic understanding of the blood-brain barrier (BBB) is essential for the novel advancements in targeting drugs specific to the brain. Neoplasm compromising the internal structure of BBB that results in impaired vasculature is called as blood tumor barrier (BTB). Besides, the BBB serves as a chief hindrance to the passage of a drug into the brain parenchyma. The small and hydrophilic drugs majorly display an absence of desired molecular characteristics required to cross the BBB. Furthermore, all classes of biologics have failed in the clinical trials of brain diseases over the past years since these biologics are large molecules that do not cross the BBB. Also, new strategies have been discovered that use the Trojan horse technology with the re-engineered biologics for BBB transport. Thus, this review delivers information about the different grades of tumors (I-IV) i.e. examples of BBB/BTB heterogenicity along with the different mechanisms for transporting the therapeutics into the brain tumors by crossing BBB. This review also provides insights into the emerging approaches of peptide delivery and the non-invasive and brain-specific molecular Trojan horse targeting technologies. Also, the several challenges in the clinical development of BBB penetrating IgG fusion protein have been discussed.

Fluorescence-based method for sensitive and rapid estimation of chlorin e6 in stealth liposomes for photodynamic therapy against cancer

Chlorin e6 is a chlorine-based porphyrin containing photosensitizer mainly used for the therapy in cancers like neck and head, early-stage lung cancer, and topical skin cancers. The present study provides a comprehensive account of a highly sensitive, precise, and validated method for the quantification of chlorin e6 in its liposomal formulation. This method is based on the systemic study of the fluorescence action of chlorin e6 in acetonitrile solvent. This experiment follows the analytical method validation parameters as per the International Conference on Harmonization (ICH). Chlorin e6 molecule exhibits strong fluorescence at a wavelength of emission 665 nm, upon excitation at a wavelength of excitation 400 nm in acetonitrile. The linearity of the fluorescence concentration plot was observed over a concentration range of 50 to 1000 ng/mL. The developed and validated method was successfully applied for the estimation of encapsulation efficiency in in-house developed stealth liposomes. Also, stock solution stability and photodegradation study of chlorin e6 were further conducted.