The date in TCSDD is self-reported by pharma companies. Besides, the data is neither publicly available nor are their methods transparent [0]. A recent peer reviewed study estimates the average cost of a cancer drug at $648M with revenue after approval being $1658.4M [1].

[0] https://www.nytimes.com/2014/11/19/upshot/calculating-the-re...

[1] https://jamanetwork.com/journals/jamainternalmedicine/fullar...