They haven't made any formal cast announcements. Maybe it is in keeping with the "mysterious secret" theme of the show
Seriously, I have seen the show twice in London and am planning to see it again on Broadway. I like the show very much - the period Victorian drama for a book, a quietly ravishing musical score by Andrew Lloyd Webber ( haunting, poignant, introspective, soaring...), innovative staging with its computerized images for background scenes ( Cool!), great acting and excellent singing opportunities for its cast!
It is going to be different from current genres - not musical comedy ( although the character and scenes with the infamous Count Fosco will certainly provide that), certainly not long on spectacles as it focuses much more on the storyline ( although it uses very effective high-tech images for its sets - they do move the story at a fast clip) - it is an adult musical of mayhem and murder in Victorian times, with wonderful music to set the mood and provide the most effective way of telling the story. Some memorable romantic and haunting songs and one particularly humorous stowstopper

... Very appealing, especially if you like serious and romantic musical theatre fare!
Jo