PTL is one of the UTMB races. It is run in teams of 2 or 3 persons, who travel the roughly 300km course around Mont Blanc largely self-sufficiently and autonomously (no trail markings, very few aid stations, frequently no trails).
The race crosses through France, Switzerland, and Italy and takes about six days. Elevation gain is about 25'000m or 26'000m. I ran the course with Dima Feinhaus and Uwe Herrmann. More here: http://utmbmontblanc.com/en/page/23/23.html