Selective Delivery of Clinically Approved Tubulin Binding Agents through Covalent Conjugation to an Active Targeting Moiety.

The efficacy and tolerability of tubulin binding agents are hampered by their low specificity for cancer cells like most clinically used anticancer agents. To improve specificity, tubulin binding agents have been covalently conjugated to agents that target cancer cells to give actively targeted drug conjugates. These conjugates are designed to increase uptake of the drug by cancer cells while having limited uptake by normal cells, thereby improving efficacy and tolerability. Approaches used include an attachment to small molecules, polysaccharides, peptides, proteins, and antibodies that exploit the overexpression of receptors for these substances. Antibody targeted strategies have been the most successful to date, with six such examples having gained clinical approval. Many other conjugate types, especially those targeting the folate receptor, have shown promising efficacy and toxicity profiles in pre-clinical models and in early-stage clinical studies. Presented herein is a discussion of the success or otherwise of the recent strategies used to form these actively targeted conjugates.

ß-Glucan extracts from the same edible shiitake mushroom Lentinus edodes produce differential in-vitro immunomodulatory and pulmonary cytoprotective effects - Implications for coronavirus disease (COVID-19) immunotherapies.

Coronavirus pneumonia is accompanied by rapid virus replication, where a large number of inflammatory cell infiltration and cytokine storm may lead to acute lung injury, acute respiratory distress syndrome (ARDS) and death. The uncontrolled release of pro-inflammatory cytokines, including interleukin (IL)-1ß and IL-6, is associated with ARDS. This constituted the first study to report on the variability in physicochemical properties of ß-glucans extracts from the same edible mushroom Lentinus edodes on the reduction of these pro-inflammatory cytokines and oxidative stress. Specifically, the impact on the immunomodulatory and cytoprotective properties of our novel in 'house' (IH-Lentinan, IHL) and a commercial (Carbosynth-Lentinan, CL) Lentinan extract were investigated using in vitro models of lung injury and macrophage phagocytosis. CL comprised higher amounts of α-glucans and correspondingly less ß-glucans. The two lentinan extracts demonstrated varying immunomodulatory activities. Both Lentinan extracts reduced cytokine-induced NF-κB activation in human alveolar epithelial A549 cells, with the IHL extract proving more effective at lower doses. In contrast, in activated THP-1 derived macrophages, the CL extract more effectively attenuated pro-inflammatory cytokine production (TNF-α, IL-8, IL-2, IL-6, IL-22) as well as TGF-ß and IL-10. The CL extract attenuated oxidative stress-induced early apoptosis, while the IHL extract attenuated late apoptosis. Our findings demonstrate significant physicochemical differences between Lentinan extracts, which produce differential in vitro immunomodulatory and pulmonary cytoprotective effects that may also have positive relevance to candidate COVID-19 therapeutics targeting cytokine storm.

Optimising the delivery of tubulin targeting agents through antibody conjugation.

Despite their side effect profile, there currently remains a heavy reliance on traditional cytotoxics and particularly tubulin targeting agents in cancer chemotherapy. To address this concern, significant progress has been made in the selective delivery of drugs to the tumour site. This review will examine the published data in support of the hypothesis that forming antibody conjugates of tubulin targeting agents is an effective approach towards their more effective delivery to the tumour site. Particular emphasis will be placed on the diversity of concepts under investigation, the efficacy of resultant conjugates, evidence of decreased resistance and the side effect profiles of the conjugates.