Wan created the story for that title with Michael Alan Nelson. He’ll produce the film and Deadline is saying he’s developing it “with an eye to direct.”
The synopsis from Boom! Studios:
What doesn’t kill you makes you stronger! Alan Gates, a cancer patient with a terminal diagnosis, is resigned to his fate…until he discovers that his tumor is actually a mysterious parasite! Granted a second lease on life and incredible, otherworldly powers, Alan must fight against an evil army buried beneath society’s skin, all the while unlocking the secrets of his forgotten past.
Wan directed last year’s The Conjuring. A sequel to that film is in the works, but it doesn’t sound like he’ll be directing.