I root cuttings without leaves all the time as long as the stem is healthy it isn't a problem. If the leaves have dropped because of a disease it might not root, if it's from dehydration it should be alright as long as it's not too dried out. I usually strip most of the foliage from cuttings (not only passies) so that more energy goes into root development.
Karyn

Generally with cuttings, you're supposed to trim most of the leaves off to reduce moisture loss. Once new roots develop, new shoots will sprout anyway. As karyn1 said, as long as the stem is green and healthy, that's what counts.

I have good luck rooting without most of the leaves as long as the growing tip is ok. I usually strip all the larger leaves and flowers/buds and leave only the tip of the vine with the tiny leaves. I have a tiny peice (about 4 inches) of a 'pink festival' passie vine that the cat knocked off, rooting in water now. It only has a tiny leaf and the growing tip. It looks like its gonna root though :)
~sjn

I have several Lutea (maybe..LOL) starting.. All of the leaves have dropped but new foliage is begging to show still no roots but green and healthy..Keep that water clean...
Chena