Cancer is a devastating disease that can be challenging to treat. Fortunately, immune cells called T-cells can be activated for tumour destruction. Signal 1 of T-cell activation is provided by antigen presentation through the (T-cell receptor/major histocompatibility complex) interaction. Signal 2 of T-cell activation is provided by a costimulatory interaction (CD28/CD80). Immune checkpoint blockade (programmed cell death-1/programmed cell death ligand-1 [PD-L1]) is a regulatory interaction controlling T-cell activation/repression. However, tumour cells may exploit checkpoint blockade for tumour survival. Immunotherapy is a favourable cancer therapy provided by 'the magic bullet' approach. Monoclonal antibodies provide cytostatic effects against checkpoint blockade. However, tumours may evolve modifications, including tumour antigen loss and tumour ligand overexpression (PD-L1). This can inactivate T-cells, causing immunotherapy resistance and low clinical responses. Bispecific antibodies possess superior properties to monoclonal antibodies provided by their spatio-temporal effects, with potential to improve anti-tumour activity. Bispecific antibodies in development were reviewed for their structures, development technologies and anti-tumour activities. FS118 and M7824 are used to treat refractory cancers, whilst Tebotelimab and XmAb20717 solely enhance T-cell activation for tumour destruction. As cellular factors can switch off T-cell activity leading to immunotherapy resistance, bispecifics with focus on T-cell activity may be ineffective in tumour targeting. This may provide an opportunity to develop a bispecific antibody as part of future research, with binding targets, PD-L1 and lymphocyte-activation gene 3. This may promote cytostatic effects for T-cell activation. Furthermore, effector cell binding may use antibody-dependent cellular cytotoxicity effects to ensure tumour destruction.

Most marketed peptide drugs are administered parenterally due to their inherent gastrointestinal (GI) instability and poor permeability across the GI epithelium. Several molecular design techniques, such as cyclisation and D-amino acid (D-AA) substitution, have been proposed to improve oral peptide drug bioavailability. However, very few of these techniques have been translated to the clinic. In addition, little is known about how synthetic peptide design may improve stability and permeability in the colon, a key site for the treatment of inflammatory bowel disease and colorectal cancer. In this study, we investigated the impact of various cyclisation modifications and D-AA substitutions on the enzymatic stability and colonic tissue permeability of native oxytocin and 11 oxytocin-based peptides. Results showed that the disulfide bond cyclisation present in native oxytocin provided an improved stability in a human colon model compared to a linear oxytocin derivative. Chloroacetyl cyclisation increased native oxytocin stability in the colonic model at 1.5 h by 30.0%, whereas thioether and N-terminal acetylated cyclisations offered no additional protection at 1.5 h. The site and number of D-AA substitutions were found to be critical for stability, with three D-AAs at Tyr, Ile and Leu, improving native oxytocin stability at 1.5 h in both linear and cyclic structures by 58.2% and 79.1%, respectively. Substitution of three D-AAs into native cyclic oxytocin significantly increased peptide permeability across rat colonic tissue; this may be because D-AA substitution favourably altered the peptide’s secondary structure. This study is the first to show how the strategic design of peptide therapeutics could enable their delivery to the colon via the oral route.

Real-time measurement is important in modern dissolution testing to aid in parallel drug characterisation and quality control (QC). The development of a real-time monitoring platform (microfluidic system, a novel eye movement platform with temperature sensors and accelerometers and a concentration probe setup) in conjunction with an in vitro model of the human eye (PK-Eye™) is reported. The importance of surface membrane permeability when modelling the PK-Eye™ was determined with a “pursing model” (a simplified setup of the hyaloid membrane). Parallel microfluidic control of PK-Eye™ models from a single source of pressure was performed with a ratio of 1:6 (pressure source:models) demonstrating scalability and reproducibility of pressure-flow data. Pore size and exposed surface area helped obtain a physiological range of intraocular pressure (IOP) within the models, demonstrating the need to reproduce in vitro dimensions as closely as possible to the real eye. Variation of aqueous humour flow rate throughout the day was demonstrated with a developed circadian rhythm program. Capabilities of different eye movements were programmed and achieved with an in-house eye movement platform. A concentration probe recorded the real-time concentration monitoring of injected albumin-conjugated Alexa Fluor 488 (Alexa albumin), which displayed constant release profiles. These results demonstrate the possibility of real-time monitoring of a pharmaceutical model for preclinical testing of ocular formulations.