Shruti S. Sawant

Background: Pseudomonas aeruginosa is one of the major pathogens that cause respiratory infections. The rise of antimicrobial resistance has prompted a need for alternatives to conventional antibiotics. Bacteriophages (phages), natural predators of bacteria, are gaining interest as an alternative therapeutic option against drug-resistant infections. However, phage viability can be lost during manufacturing and delivery. Recent studies show that phages can be taken up by lung epithelial cells, which makes fewer phages available for antibacterial action against extracellular bacteria P. aeruginosa in the airways. Methods: In this study, we encapsulated phages in liposomes using thin film hydration. The effect of processing conditions and phage loading titer on the phage encapsulation and viability was studied. The impact of nebulization on phage viability was tested using an air-jet nebulizer (PARI-LC Plus). Phage cellular uptake was evaluated using an in vitro H441 lung epithelial cell model, grown at the air–liquid interface. Results: Our results demonstrate favorable encapsulation (58 ± 6.02%) can be achieved with minimum loss in phage titer (0.64 ± 0.21 log) by using a low phage titer for hydration. The liposomal formulations exhibited controlled release of phages over 10 h. The formulation also reduced the loss of phage viability during nebulization from 1.55 ± 0.04 log (for phage suspension) to 1.08 ± 0.05 log (for phage liposomes). Encapsulation of phages in liposomes enabled a two-fold reduction in phage cellular uptake and longer extracellular phage retention in the human lung epithelial cell monolayer. Conclusions: Our results indicate that liposomal encapsulation favors phage protection and improves phage availability for antibacterial activity. These findings highlight the potential of liposomes for inhaled phage delivery.

Background: Non-small cell lung cancer (NSCLC) is a leading cause of cancer deaths globally. The most extensive treatment is Tyrosine Kinase Inhibitors (TKIs) that target epidermal growth factor receptor (EGFR) overexpression. Osimertinib, a third-generation TKI is approved to target EGFR exon 19 deletions or exon 21 L858R mutations. However, resistance is inevitable due to emergence of triple mutations (sensitizing mutations, T790M and C797S). To overcome this challenge, a combinatorial approach was used wherein Osimertinib liposomes were conjugated with cetuximab (CTX), an anti-EGFR monoclonal antibody, to improve drug efficacy and delivery. Additionally, pulmonary administration was employed to minimize systemic toxicity and achieve high lung concentrations. Methods: Osimertinib liposomes (OB-LPs) were prepared using thin film hydration method and immunoliposomes (CTX-OB-LPs) were prepared by conjugating the OB-LPs surface with CTX. Liposomes were characterized for particle size, zeta-potential, drug loading, antibody conjugation efficiency, in vitro drug release, and aerosolization performance. Further, the in vitro efficacy of immunoliposomes was evaluated in H1975 cell line. Results: Immunoliposomes exhibited a particle size of 150 nm, high antibody conjugation efficiency (87%), efficient drug release, and excellent aerosolization properties with an aerodynamic diameter of 3 μm and fine particle fraction of 88%. Furthermore, in vitro studies in H1975 cells showed enhanced cytotoxicity with CTX-OB-LPs displaying 1.7-fold reduction and 1.2-fold reduction in IC₅₀ compared to Osimertinib and OB-LPs, respectively. The CTX-OB-LPs also significantly reduced tumor cell migration and colonization compared to Osimertinib and OB-LPs. Conclusions: These successful results for EGFR-targeting inhalable immunoliposomes exhibited potential for contributing to greater anti-tumor efficacy for the treatment of non-small cell lung cancer.