One dose costs $4,000. A full treatment is more than one dose. That sounds like over 100 doses if all you do is pop some pills. If I had to guess it probably isn't 100 doses but you have to do other things like stay in a hospital during the course of treatment, other tests, or something else that adds to the price tag.

AKA the price tag on a service is usually much more than the cost of goods sold.