Sasha Larsen Akins Poster 2025

Dr Sasha Larsen Akins

Seattle Children's Research Institute, USA

Building reproducible and escalating preclinical models for mycobacteriophage efficacy testing

Poster Abstract

Human disease caused by pathogenic mycobacteria, from Mycobacterium tuberculosis (M.tb) to nontuberculous mycobacteria, cause a significant amount of morbidity and mortality globally. No prevention of infection or disease vaccines are currently licensed and antibiotic resistance is an ever increasing problem. Bacteriophage (phage) therapy is a potential strategy to treat infected individuals and possibly limit the spread of M.tb to new patients with population level-impact. We have developed an escalating suite of in vitro assays to evaluate mycobacteriophages singly and as cocktails against different lineages of M.tb, over time and in conditions of hypoxia where bacteria may be in difficult to kill stationary growth phases or be affected by antibiotics.

In vitro testing suggests that the phages tested were able to kill M.tb under hypoxia and durably over time. Some phage demonstrated antagonism with some classes of antibiotics in in vitro checkboard assays. In vivo preclinical mouse models have demonstrated that phage delivered reproducibly by aerosol can colocalize to lung lobes where M.tb typically resides. Pharmacokinetic studies suggest that phage delivered intravenously are cleared more rapidly from the lungs compared to when phage are delivered by aerosol. We also observed that repeated aerosol delivery of phage was less immunogenic and did not produce neutralizing humoral responses, compared to intravenous delivery after 6 weeks’ time in C57BL/6 mice. Repeated daily delivery of purified phage was well tolerated and did not lead to overt changes in weight or induction of proinflammatory cytokines in BALB/c mice previously infected with M.tb. In a normal human population we observed that only 5% of samples had antibodies to our mycobacteriophage of interest, although none were neutralizing. This platform for evaluating phage and anti-M.tb drug synergy is a reproducible preclinical efficacy model for future evaluations to support the investment in clinical trials for phage therapy against mycobacteria.