Field Discoveries (Case Reports)

Field discoveries represent a unique source of innovation leading to drug repurposing. This chapter follows the process by which field discoveries made by clinicians in their everyday practice are diffused, validated in larger trials, and adopted into clinical practice through real-world drug repurposing (off-label use), sometimes gaining regulatory approval. The significance of publishing case reports is highlighted. The relevance of field discoveries for drug repurposing is illustrated using several examples. Propofol that was approved as an anesthetic was repurposed to treat morphine-induced pruritus, rituximab approved for the treatment of certain types of non-Hodgkin's lymphoma was repurposed for prostate cancer, dipyridamole introduced to treat angina was repurposed for pterygium, thalidomide introduced as a sleeping aid – and soon banned because of its teratogenicity in the developing embryo – was repurposed to treat leprosy, and botulinum neurotoxin type A approved for strabismus was repurposed for the treatment of facial wrinkles. The serendipitous character of many field discoveries is emphasized. The embracement of real-world evidence by regulatory authorities strengthens the efforts to make the road from field discovery to drug repurposing an easier one and will benefit many patients suffering from currently incurable diseases.