European regulatory aspects of phage therapy: magistral phage preparations.

Bacteriophages (phages) are bacterial viruses, and have been used for more than a century to combat bacterial infections, particularly in Poland and in the former Soviet Union. The antimicrobial resistance crisis has triggered a renewed interest in the therapeutic use of natural phages. The capacity of phages to specifically target pathogenic strains (sparing commensal bacteria), to adapt to these strains, and to rapidly overcome bacterial resistance, makes them suitable for flexible therapeutic approaches. To maximally exploit these advantages phages offer over conventional 'static' drugs such as traditional small molecule-type antibiotics, it is important that these sustainable phage products are not submitted to the traditional (long and expensive) medicinal product development and licensing pathways. Here we discuss the extrapolation of the Belgian 'magistral preparation' phage therapy framework to the European level, enabling an expeditious re-introduction of personalized phage therapy into Europe.