[evandijk70]

All of the above, but my guess would be that the most expensive part is usually running the phase III clinical trial. You have to pay data managers to perform the randomization, train doctors and nurses to administer it, and the hospital for the added time it takes them to run the trial, pay the statisticians that perform the analysis, an agency that helps prepare the application, etcetera. You have to recruit patients, gather informed consent (though that is sometimes done by doctors and nurses). Also, you have to give the drug for free, since insurance companies do not cover experimental drugs. Sometimes patients also receive a fee for participating in the trial. All in all, the median cost of pivotal trials is 50 million dollars. This is the cost after you already did studies to discover the drug, and determine the dosage. Half of these trials fail, and all the previous investments are lost in that case.

[1] https://bmjopen.bmj.com/content/10/6/e038863